Co-reporter:Hongbin Zhang, Hongxia Zhang, Yang Zhao, Zhangping Shi, Yahong Zhang, and Yi Tang
Chemistry of Materials November 14, 2017 Volume 29(Issue 21) pp:9247-9247
Publication Date(Web):October 10, 2017
DOI:10.1021/acs.chemmater.7b03121
Direct synthesis by assembly of precursor nanoparticles is a promising strategy for preparing distinct mesoscopic-structured crystals, especially when high controllability is realized. However, uncertain properties of amorphous precursors and inner complicacy of crystallization mechanisms hamper controllable synthesis of zeolite mesocrystals. Here, we develop a salt-aided seed-induced organic-free method to facilely synthesize anisotropic MFI-type nanorod-bundle zeolite mesocrystals. An epitaxial, anisotropic assembly and crystallization of precursor particles on seed crystals is successfully achieved via a distinctively dynamic, nonclassical process, from relatively disordered to ordered attachment (OA), triggering an enhanced one-dimensional (1D) growth, thus constructing a unique core–shell–shell structure. This work sheds new light on the insights of both zeolite mesocrystal properties and a nonclassical crystallization mechanism. With an understanding of the mechanism, this nonclassical process can be exploited to systematically tune mesocrystal properties and create zeolite materials with novel or enhanced physical and chemical performance.
Co-reporter:Yang Zhao, Hongbin Zhang, Peicheng Wang, Fangqi Xue, Zhaoqi Ye, Yahong Zhang, and Yi Tang
Chemistry of Materials April 25, 2017 Volume 29(Issue 8) pp:3387-3387
Publication Date(Web):March 28, 2017
DOI:10.1021/acs.chemmater.6b03813
The morphology and porosity of zeolite play a significant role in the activity and selectivity of catalytic reactions. It is a dream to optionally modulate zeolite morphology by regulating the crystallization process on the basis of comprehensively understanding the mechanisms. Herein, a series of MTW zeolite mesocrystals can be consciously fabricated with morphologies from a dense structure to a loose one of an oriented nanocrystallite aggregate by changing the H2O/SiO2 ratio. Their intertwined classical/nonclassical crystallization processes are investigated comprehensively. The results indicate that the crystallization of MTW zeolite takes place by a chain of events, including the formation of wormlike particles (WLPs), their aggregation, and crystallization of aggregates. MTW with a loose structure mainly crystallizes by an internal reorganization after a fast aggregation of WLPs in a concentrated system. On the other hand, the dense structure of MTW is realized via the co-occurrence of a coalescence of the participating WLPs during its crystal growth with a slower rate in a dilute system. Moreover, the advantages of MTW with a loose structure are confirmed through cumene cracking and 1,2,4-trimethylbenzene transformation. This method could pave the way for the synthesis of other zeolites with diverse morphologies and/or mesoporosities via subtle regulation of the crystallization pathway.
Co-reporter:Lei Wang;Sheng-cai Zhu;Mei-kun Shen;Hai-wen Tian;Song-hai Xie;Hong-bin Zhang; Ya-hong Zhang; Yi Tang
Angewandte Chemie 2017 Volume 129(Issue 39) pp:11926-11930
Publication Date(Web):2017/09/18
DOI:10.1002/ange.201704499
AbstractScrew dislocation structures in crystals are an origin of symmetry breaking in a wide range of dense-phase crystals. Preparation of such analogous structures in framework-phase crystals is of great importance in zeolites but is still a challenge. On the basis of crystal-structure solving and model building, it was found that the two specific intergrowths in MTW zeolite produce this complex fractal and spiral structure. With the structurally determined parameters (spiral pitch h, screw angle θ, and spatial angle ψ) of Burgers circuit, the screw dislocation structure can be constructed by two different dimensional intergrowth sections. Thus the reported complexity of various dimensions in diverse crystals can be unified.
Co-reporter:Lei Wang;Sheng-cai Zhu;Mei-kun Shen;Hai-wen Tian;Song-hai Xie;Hong-bin Zhang; Ya-hong Zhang; Yi Tang
Angewandte Chemie International Edition 2017 Volume 56(Issue 39) pp:11764-11768
Publication Date(Web):2017/09/18
DOI:10.1002/anie.201704499
AbstractScrew dislocation structures in crystals are an origin of symmetry breaking in a wide range of dense-phase crystals. Preparation of such analogous structures in framework-phase crystals is of great importance in zeolites but is still a challenge. On the basis of crystal-structure solving and model building, it was found that the two specific intergrowths in MTW zeolite produce this complex fractal and spiral structure. With the structurally determined parameters (spiral pitch h, screw angle θ, and spatial angle ψ) of Burgers circuit, the screw dislocation structure can be constructed by two different dimensional intergrowth sections. Thus the reported complexity of various dimensions in diverse crystals can be unified.
Co-reporter:Zhangping Shi;Kaiqi Nie;Zheng-Jiang Shao;Boxu Gao;Huanlei Lin;Hongbin Zhang;Bolun Liu;Yangxia Wang;Yahong Zhang;Xuhui Sun;Xiao-Ming Cao;P. Hu;Qingsheng Gao
Energy & Environmental Science (2008-Present) 2017 vol. 10(Issue 5) pp:1262-1271
Publication Date(Web):2017/05/17
DOI:10.1039/C7EE00388A
To explore high-performance electrocatalysts, electronic regulation on active sites is essentially demanded. Herein, we propose controlled phosphorus doping to effectively modify the electronic configuration of nanostructured Mo2C, accomplishing a benchmark performance of noble-metal-free electrocatalysts in the hydrogen evolution reaction (HER). Employing MoOx–phytic acid–polyaniline hybrids with tunable composition as precursors, a series of hierarchical nanowires composed of phosphorus-doped Mo2C nanoparticles evenly integrated within conducting carbon (denoted as P-Mo2C@C) are successfully obtained via facile pyrolysis under inert flow. Remarkably, P-doping into Mo2C can increase the electron density around the Fermi level of Mo2C, leading to weakened Mo–H bonding toward promoted HER kinetics. Further density functional theory calculations show that the negative hydrogen-binding free energy (ΔGH*) on pristine Mo2C gradually increases with P-doping due to electron transfer and steric hindrance by P on the Mo2C surface, indicating the effectively weakened strength of Mo–H. With optimal doping, a ΔGH* approaching 0 eV suggests a good balance between the Volmer and Heyrovsky/Tafel steps in HER kinetics. As expected, the P-Mo2C@C nanowires with controlled P-doping (P: 2.9 wt%) deliver a low overpotential of 89 mV at a current density of −10 mA cm−2 and striking kinetic metrics (onset overpotential: 35 mV, Tafel slope: 42 mV dec−1) in acidic electrolytes, outperforming most of the current noble-metal-free electrocatalysts. Elucidating feasible electronic regulation and the remarkably enhanced catalysis associated with controlled P-doping, our work will pave the way for developing efficient noble-metal-free catalysts via rational surface engineering.
Co-reporter:Peicheng Wang;Yang Zhao;Hongbin Zhang;Tao Yu;Yahong Zhang
RSC Advances (2011-Present) 2017 vol. 7(Issue 38) pp:23272-23278
Publication Date(Web):2017/04/27
DOI:10.1039/C7RA02864D
A series of diquaternary pyrazolium-derived organic templates (N,N′-dimethyl-N,N′-1,6-dihexylidenedipyrazolium, N,N′-diethyl-N,N′-1,6-dihexylidenedipyrazolium, N,N′-dipropyl-N,N′-1,6-dihexylidenedipyrazolium, denoted as 6C-DMP, 6C-DEP, 6C-DPP, respectively) with methyl, ethyl and propyl groups substituted on the N atom of pyrazole ring at both terminals have been used in the synthesis of high silica MTW and MFI zeolites. Through combining the characterization results, including XRD, NMR, elemental analysis, TG, XRF, FE-SEM, N2 sorption and FE-TEM, with molecular mechanics simulations to explore the location, orientation and the interaction energies of the three templates, we confirmed the state of templates in zeolite framework, carefully characterized their morphology/structure properties, and finally investigated their different spatial effects for the zeolite formation. The study found that 6C-DMP and 6C-DEP are able to produce MTW, while 6C-DPP is able to produce MFI. 6C-DMP, owing to a good match with the MTW framework and can be used to synthesize regular MTW zeolite with few defects. The MTW zeolite prepared by using 6C-DEP as a template presents more defects and irregular macromorphology due to a relatively poor match to the MTW framework. 6C-DPP can get MFI other than MTW due to a larger spatial hindrance, and it is located in the MFI framework with a special spatial orientation.
Co-reporter:Huanlei Lin;Ning Liu;Zhangping Shi;Yulin Guo;Qingsheng Gao
Advanced Functional Materials 2016 Volume 26( Issue 31) pp:5590-5598
Publication Date(Web):
DOI:10.1002/adfm.201600915
Efficient hydrogen evolution reaction (HER) over noble-metal-free electrocatalysts provides one of the most promising pathways to face the energy crisis. Herein, facile cobalt-doping based on Co-modified MoOx–amine precursors is developed to optimize the electrochemical HER over Mo2C nanowires. The effective Co-doping into Mo2C crystal structure increases the electron density around Fermi level, resulting in the reduced strength of Mo–H for facilitated HER kinetics. As expected, the Co-Mo2C nanowires with an optimal Co/Mo ratio of 0.020 display a low overpotential (η10 = 140 and 118 mV for reaching a current density of –10 mA cm−2; η100 = 200 and 195 mV for reaching a current density of –100 mA cm−2), a small Tafel slope (39 and 44 mV dec−1), and a low onset overpotential (40 and 25 mV) in 0.5 m H2SO4 and 1.0 m KOH, respectively. This work highlights a feasible strategy to explore efficient electrocatalysts via engineering on composition and nanostructure.
Co-reporter:Huanlei Lin, Zhangping Shi, Sina He, Xiang Yu, Sinong Wang, Qingsheng Gao and Yi Tang
Chemical Science 2016 vol. 7(Issue 5) pp:3399-3405
Publication Date(Web):12 Feb 2016
DOI:10.1039/C6SC00077K
Exploring efficient noble-metal free electrocatalysts for the hydrogen evolution reaction (HER) is one of the most promising pathways for facing the energy crisis. Herein, MoC–Mo2C heteronanowires composed of well-defined nanoparticles were accomplished via controlled carbonization, showing excellent HER activity, fast kinetic metrics and outstanding stability in both acid and basic electrolytes. In particular, the optimal one consisting of 31.4 wt% MoC displayed a low overpotential (η10 = 126 and 120 mV for reaching a current density of −10 mA cm−2), a small Tafel slope (43 and 42 mV dec−1) and a low onset overpotential (38 and 33 mV) in 0.5 M H2SO4 and 1.0 M KOH, respectively. Such prominent performance, outperforming most of the current noble-metal free electrocatalysts, was ascribed to the carbide surface with an optimized electron density, and the consequently facilitated HER kinetics. This work elucidates a feasible way toward efficient electrocatalysts via heteronanostructure engineering, shedding some light on the exploration and optimization of catalysts in energy chemistry.
Co-reporter:Bin Zhang, Yahong Zhang, Yuanyuan Hu, Zhangping Shi, Arepati Azhati, Songhai Xie, Heyong He, and Yi Tang
Chemistry of Materials 2016 Volume 28(Issue 8) pp:2757
Publication Date(Web):April 4, 2016
DOI:10.1021/acs.chemmater.6b00503
A facile microexplosion approach has been successfully developed to produce an interwoven mesopore network in zeolite crystals via the rushing-out of gases generated by decomposition of H2O2 under microwave irradiation. This “gas imprint” method creates the mesopores from the interior crystal toward the exterior, in line with the direction of the pristine microporous channels, and is different from the previous methods in which the reagent starts an attack from the crystal surface and perforates inward. The created mesopores extend throughout the whole crystal and highly blend into the intrinsic micropores around. The acidity of zeolite is also well preserved due to this unique mechanism of pore creation. The continuous high quality hierarchical architecture with intact acidity leads to a notable increase both in the conversion of 2-methoxynaphthalene acylation and in the selectivity to the target molecule of 2-acetyl-6-methoxynapthalene. This microexplosion approach offers an efficient synthesis protocol of zeolitic hierarchy integrating intersected mesoporosity and zeolitic microporosity and opens the way to the rational organization of meso- and microporosity for maximal advantage in applications.
Co-reporter:Zhangping Shi, Yangxia Wang, Huanlei Lin, Hongbin Zhang, Meikun Shen, Songhai Xie, Yahong Zhang, Qingsheng Gao and Yi Tang
Journal of Materials Chemistry A 2016 vol. 4(Issue 16) pp:6006-6013
Publication Date(Web):17 Mar 2016
DOI:10.1039/C6TA01900E
The hydrogen evolution reaction using noble-metal free electrocatalysts has captured increasing attention due to its importance in renewable hydrogen production. Herein, a highly active and stable electrocatalyst of MoC encapsulated by graphitized carbon shells (nanoMoC@GS) has been developed via an in situ carburization of a Mo-based metal–organic framework (Mo-MOF) with the atomic periodic structure. The ultrafine MoC nanoparticles (∼3 nm) confined by 1–3 layered graphite shells significantly favor the efficient HER in both acidic and basic media. In particular, a low overpotential (η10 = 124 and 77 mV at a current density of −10 mA cm−2), a small Tafel slope (43 and 50 mV dec−1) and a high exchange current density (j0 = 0.015 and 0.212 mA cm−2) are achieved on nanoMoC@GS in 0.5 M H2SO4 and 1.0 M KOH, respectively. Such remarkable activity, outperforming most current noble-metal-free electrocatalysts, stems from the cooperative/synergistic effects of ultrafine MoC nanostructure, ultrathin and conductive graphitized carbon shells, and enriched porosity. This work demonstrates a feasible way to design high-performance electrocatalysts via converting “atomic contact” hybrid structures (e.g., MOFs), illustrating a new perspective for developing nanocatalysts in the energy chemistry field.
Co-reporter:Weilin Song, Bin Zhang, Lifeng Chen, Jing Shi, Xiaowei Cheng, Lianghua Wu, Weimin Yang, Jian Zhou, Yahong Zhang, Yuewu Tao and Yi Tang
Catalysis Science & Technology 2016 vol. 6(Issue 10) pp:3559-3567
Publication Date(Web):11 Dec 2015
DOI:10.1039/C5CY01144B
A core–shell structured catalyst is considered effective for regulating product distribution in a complex reaction network. By systematically analyzing the behaviors of an Fe–Mn–Cu/SiO2@silicalite-1 core–shell catalyst in Fischer–Tropsch synthesis, a unique temperature-dependent role of the silicalite-1 shell is demonstrated on the distribution of products via modulation of the intra- and inter-pellet secondary reactions, which successfully fulfills synchronous increments of CO conversion, light olefin/light paraffin ratio (C2–4=/C2–40) and C2–4= selectivity, opposite to the behavior of a naked industrial Fe–Mn–Cu/SiO2 catalyst. This effect could be attributed to the different diffusion limitation of the silicalite-1 shell on various reactants/products in different temperature ranges. Such a discovery not only rationally explains the excellent performance of the core–shell catalyst on C2–4= production but also provides a new clue for the design of catalysts in complex reaction networks.
Co-reporter:Wenqian Jiao, Xuezhong Wu, Teng Xue, Gang Li, Weiwen Wang, Yangxia Wang, YiMeng Wang, Yi Tang, and Ming-Yuan He
Crystal Growth & Design 2016 Volume 16(Issue 9) pp:5166
Publication Date(Web):August 1, 2016
DOI:10.1021/acs.cgd.6b00723
Well-crystallized boehmite nanoparticles showing different sizes and morphologies were fabricated in an organic additive-free cationic–anionic double hydrolysis method using inorganic aluminum chloride salt and sodium aluminate as dual aluminum sources. By adjusting the molar ratios of Al3+/AlO2– in the synthesis recipe, the boehmite particles’ shapes could be controllably tuned from two-dimensional flakes to one-dimensional (1D) rods, needles, and even fibers with enhanced particles’ aspect ratios. Through X-ray diffraction and high resolution transmission electron microscopy measurements, details of the microstructural features for boehmite particles were gained, and thus the growth habits are discussed, where in strong alkaline synthesis medium with a low Al3+/AlO2– molar ratio, dispersed nanoflakes grew with (010) and (101) faces as basal and lateral surfaces, while 1D nanoparticles, i.e. nanorods, nanoneedles, and nanofibers preferentially grew along the [100] direction with (100) and (101) faces unexposed when Al3+/AlO2– molar ratios were gradually raised. Additionally, the impacts of pH values and Cl– ions in the suspensions to the particles shapes are also discussed. The evolution of boehmite morphologies and the resultant enlargement of aspect ratios led to increased total surface charges (ζ-potential) and higher isoelectric points of boehmite samples which would benefit the stabilization of particles’ suspensions and improvement of surface functionalization abilities.
Co-reporter:Wen Qian Jiao, Jian Ding, Zong Bo Shi, Xiao Min Liang, Yi Meng Wang, Ya Hong Zhang, Yi Tang, Ming-Yuan He
Microporous and Mesoporous Materials 2016 Volume 228() pp:237-247
Publication Date(Web):1 July 2016
DOI:10.1016/j.micromeso.2016.03.045
•Meso/microporous zeolite Y composites are prepared from commercial NaY zeolite in two-step method.•Hierarchy factors (HF) of the zeolite Y composites can be adjusted from 0.04 to 0.16.•The essential effects of lactic acid on the formation of diverse mesoporous domains are systematically investigated.•The zeolite Y composites allow much better performances in the acetalization reactions of cyclohexanone with pentaerythritol.Series of meso/microporous zeolite Y composites with adjustable hierarchy factors (HF) from 0.04 to 0.16, are prepared from commercial NaY zeolite (Si/Al = 2.5) by the two-step method with first lactic acid leaching and then CTAB-assisted ammonia treatment. The essential effect of lactic acid on the formation of diverse mesoporous domains in microporous crystals are systematically investigated. A possible scheme is proposed. The lactic acid leaching process is found to be very crucial to controllably remove the framework aluminum and regulate the amount/size of intra-crystal amorphous silicon-rich domains, which then evolve to mesostructures within the microporous crystals via structural re-arrangement/dissolution-reassembly process during the CTAB-assisted ammonia treatment. Varying the lactic acid concentrations would result in different crystallinity preservations and diverse proportions/dispersity of mesoporous regions, and thus well tune the HF values of the final composites. The zeolite Y composites with moderate mesoporosities allow much better performances in the acetalization reactions of cyclohexanone with pentaerythritol due to the improved diffusion ability of large sized guest molecules, whereas accompanying loss of acidity would depress reactivities of the treated samples for dehydration of small isopropanol.
Co-reporter:Hongxia Zhang, Hongbin Zhang, Peicheng Wang, Yang Zhao, Zhangping Shi, Yahong Zhang and Yi Tang
RSC Advances 2016 vol. 6(Issue 53) pp:47623-47631
Publication Date(Web):04 May 2016
DOI:10.1039/C6RA08211D
Seed-assisted synthesis has been demonstrated as a green and facile route to produce useful zeolites with several frameworks, and meanwhile shows the potential to selectively template the formation of specific structured crystals. In view of the difficulty of directly synthesizing zeolite mordenite (MOR) with short 1D, 12-MR channels, we proposed a plausible synthetic route of exotic seed-assisted conversion (ESAC), starting from aluminosilicate gel containing zeolite beta (BEA) seeds to MOR nanocrystals. Through judiciously adjusting the synthetic conditions, including NaF/Si, OH−/Si, hydrothermal temperature and added zeolite BEA seeds, nano-crystallite assembled zeolite MOR nanoparticles with rich inter-crystallite mesoporosity, high crystallinity, perfect framework, and high catalytic activity for low-density polyethylene cracking, were fast transformed under a low seeded, organic template-free system. The combined investigation of synthetic conditions and the crystallization process deepened the understanding on this special crystallization behaviour.
Co-reporter:Hongbin Zhang;Yang Zhao;Hongxia Zhang;Peicheng Wang;Zhangping Shi;Jianjiang Mao; Yahong Zhang ; Yi Tang
Chemistry - A European Journal 2016 Volume 22( Issue 21) pp:7141-7151
Publication Date(Web):
DOI:10.1002/chem.201600028
Abstract
Diffusion limitation in micropores of zeolites leads to a demand for optimization of zeolite morphology and/or porosity. However, tailoring crystallization processes to realize targeted morphology/porosity is a major challenge in zeolite synthesis. On the basis of previous work on the salt-aided, seed-induced route, the template effect of seeds on the formation of micropores, mesopores and even macropores was further explored to selectively achieve desired hierarchical architectures. By carefully investigating the crystallization processes of two typical samples with distinct crystal morphologies, namely, 1) nanocrystallite-oriented self-assembled ZSM-5 zeolite and 2) enriched intracrystal mesoporous ZSM-5 zeolite, a detailed mechanism is proposed to clarify the role of silicalite-1 seeds in the formation of diverse morphologies in a salt-rich heterogeneous system, combined with the transformation of seed-embedded aluminosilicate gel. On the basis of these conclusions, the morphologies/porosities of products were precisely tailored by deliberately adjusting the synthesis parameters (KF/Si, tetrapropylammonium bromide/Si and H2O/Si ratios and type of organic template) to regulate the kinetics of seed dissolution and seed-induced recrystallization. This work may not only provide a practical route to control zeolite crystallization for tailoring crystal morphology, but also expands the knowledge of crystal growth mechanisms in a heterogeneous system.
Co-reporter:Jing Shi, Yangdong Wang, Weimin Yang, Yi Tang and Zaiku Xie
Chemical Society Reviews 2015 vol. 44(Issue 24) pp:8877-8903
Publication Date(Web):16 Nov 2015
DOI:10.1039/C5CS00626K
The kaleidoscopic applications of zeolite catalysts (zeo-catalysts) in petrochemical processes has been considered as one of the major accomplishments in recent decades. About twenty types of zeolite have been industrially applied so far, and their versatile porous architectures have contributed their most essential features to affect the catalytic efficiency. This review depicts the evolution of pore models in zeolite catalysts accompanied by the increase in industrial and environmental demands. The indispensable roles of modulating pore models are outlined for zeo-catalysts for the enhancement of their catalytic performances in various industrial processes. The zeolites and related industrial processes discussed range from the uni-modal micropore system of zeolite Y (12-ring micropore, 12-R) in fluid catalytic cracking (FCC), zeolite ZSM-5 (10-R) in xylene isomerization and SAPO-34 (8-R) in olefin production to the multi-modal micropore system of MCM-22 (10-R and 12-R pocket) in aromatic alkylation and the hierarchical pores in FCC and catalytic cracking of C4 olefins. The rational construction of pore models, especially hierarchical features, is highlighted with a careful classification from an industrial perspective accompanied by a detailed analysis of the theoretical mechanisms.
Co-reporter:Hongbin Zhang, Zhijie Hu, Liang Huang, Hongxia Zhang, Kunshan Song, Lei Wang, Zhangping Shi, Jianxue Ma, Yan Zhuang, Wei Shen, Yahong Zhang, Hualong Xu, and Yi Tang
ACS Catalysis 2015 Volume 5(Issue 4) pp:2548
Publication Date(Web):March 11, 2015
DOI:10.1021/cs5019953
Selective dehydration of glycerol to value-added acrolein is an interesting catalytic process not only owing to the increasing coproduction of glycerol in the biodiesel production but also due to the emerging perspectives to provide a sustainable route for acrolein production. The use of zeolites in glycerol dehydration is a very promising way with high performance, but these microporous catalysts are often severely constrained by the rapid catalyst deactivation due to coke formation. Although the introduction of hierarchical structure in microporous zeolite crystals is believed to be an effective approach to enhance their activity and lifetime, the relationship between the mesoporosity and catalytic performance is still controversial. In this paper, four kinds of typical hierarchical ZSM-5 catalysts with diverse mesoporosity and similar microporosity/acidity are prepared by the salt-aided seed-induced route. By systematically studying their catalytic performances, the effects of various mesopore types on the glycerol dehydration are declared, including pore size, amount, distribution, and connectivity. The sample with open and interconnected mesopore architecture display the high activity, long lifetime, and improved selectivity, while the worse behavior of closed and small mesopores is attributed to the mass transfer limitations and/or the in-pore condensation of reactant or its heavier derivatives. Moreover, the combined effect of acidity and hierarchical structure was also explored by changing the framework Si/Al ratio. The findings emphasize the necessity of reasonably designing the zeolite catalysts with proper hierarchical structure and acidity for maximal catalytic advantage.Keywords: acidity; glycerol dehydration; hierarchical structure; structure-performance relationship; zeolite
Co-reporter:Q. Wu, L. Liao, Q. Zhang, Y. Nie, J. Xiao, S. Wang, S. Dai, Q. Gao, Y. Zhang, X. Sun, B. Liu, Y. Tang
Electrochimica Acta 2015 Volume 158() pp:42-48
Publication Date(Web):10 March 2015
DOI:10.1016/j.electacta.2015.01.115
•An intercalation-in situ carbonization strategy is reported for multilayer material.•The obtained multilayer hybrid material exhibits enhanced ORR performance.•It is confirmed that the oxygen vacancy and synergetic coupling effect are crucial.Advanced materials for electrocatalytic oxygen reduction reaction (ORR) is crucial to a number of renewable energy applications. Herein, a hybrid of nitrogen-doped graphene (N-graphene) and NbOx (x = 2∼2.5) semiconductor nanosheets with sandwich-like structure has been designed and synthesized via a strategy of intercalation-in situ carbonization. The obtained multilayer hybrid material exhibits quite positive onset potential of ORR, good stability and excellent selectivity for ORR with high methanol tolerance. The enhanced performance could be attributed to the active oxygen vacancy from the partial reduction of Nb (V) during the carbonization process and the synergetic coupling effect resulting from the molecular level contact of N-graphene and NbOx (x = 2∼2.5) nanosheets, which makes it a promising substitute of platinum-based materials for renewable energy applications.
Co-reporter:Lei Liao, Sinong Wang, Jingjing Xiao, Xiaojun Bian, Yahong Zhang, Micheál D. Scanlon, Xile Hu, Yi Tang, Baohong Liu and Hubert H. Girault
Energy & Environmental Science 2014 vol. 7(Issue 1) pp:387-392
Publication Date(Web):17 Oct 2013
DOI:10.1039/C3EE42441C
A highly active and stable electrochemical catalyst of nanoporous molybdenum carbide nanowires (np-Mo2C NWs) has been developed for hydrogen evolution reaction (HER). The np-Mo2C NWs were synthesized simply by pyrolysis of a MoOx/amine hybrid precursor with sub-nanosized periodic structure under an inert atmosphere. The enriched nanoporosity and large reactive surface of these highly dispersed nanowires with uniform Mo2C nanocrystallites provide an efficient electrocatalysis, leading to their superior HER activity with lower onset overpotential and higher current densities than Mo2C microparticles. This study opens a new perspective for the development of highly active non-noble electrocatalysts for hydrogen production from water splitting.
Co-reporter:Qingsheng Gao, Ning Liu, Sinong Wang and Yi Tang
Nanoscale 2014 vol. 6(Issue 23) pp:14106-14120
Publication Date(Web):24 Sep 2014
DOI:10.1039/C4NR05035E
The rational design of metal non-oxides is important for their catalytic application, which is however limited by the fact that the current synthetic strategies are short of effective control over formation reactions. Recently, the hybrids evenly integrating organic with inorganic molecules on a nanoscale significantly provided quasi-homogeneous reactions towards well-defined nanocatalysts of metal non-oxides, in which their structures and properties can be modulated in a wide range. Focusing on the nanostructures and the related catalytic behaviors, this feature article seeks to provide some control on the key structures and properties of metal non-oxides (e.g. carbides, nitrides, sulfides and selenides). It is thus anticipated to shed some light on the development of emerging materials for efficient catalysis, especially those used in energy utilization.
Co-reporter:Xiaowei Cheng, Jianjiang Mao, Xinchun Lv, Tao Hua, Xiaopeng Cheng, Yingcai Long and Yi Tang
Journal of Materials Chemistry A 2014 vol. 2(Issue 5) pp:1247-1251
Publication Date(Web):22 Nov 2013
DOI:10.1039/C3TA14235C
Nanosized zeolite beta with a tuneable crystal morphology and size, rich intercrystalline mesoporosity and high catalytic activity for low-density polyethylene cracking, was fast transformed from a low-seeded, low-templated dry gel by a seeding-steam-assisted conversion method with a small quantity of water; the crystallization of zeolite beta is well induced within 28 h at a TEAOH/SiO2 of 0.1 with the aid of 1% seeds.
Co-reporter:Zhijie Hu, Hongbin Zhang, Lei Wang, Hongxia Zhang, Yahong Zhang, Hualong Xu, Wei Shen and Yi Tang
Catalysis Science & Technology 2014 vol. 4(Issue 9) pp:2891-2895
Publication Date(Web):10 Jun 2014
DOI:10.1039/C4CY00376D
A highly stable MTP (methanol to propylene) catalyst, boron-modified hierarchical nanocrystalline ZSM-5 zeolite, has been constructed by a facile salt-aided seed-induced route. The cooperative effect of its hierarchical structure and modified acidity gives rise to a significantly stable activity (725 h) even at a high WHSV (weight hourly space velocity) of 4.0 h−1.
Co-reporter:Pengfei Xie, Lifeng Chen, Zhen Ma, Chengyun Huang, Zhiwei Huang, Yinghong Yue, Weiming Hua, Yi Tang, Zi Gao
Microporous and Mesoporous Materials 2014 200() pp: 52-60
Publication Date(Web):
DOI:10.1016/j.micromeso.2014.08.020
Co-reporter:Gaoxiang Liu, Sinong Wang, Yuting Nie, Xuhui Sun, Yahong Zhang and Yi Tang
Journal of Materials Chemistry A 2013 vol. 1(Issue 35) pp:10120-10129
Publication Date(Web):10 Jun 2013
DOI:10.1039/C3TA11479A
A simple one-step hydrothermal route is developed to synthesize one-dimensional (1D) hexagonal tungsten bronze (HTB) nanostructures. The key to this route is utilizing the electrostatic attraction between negatively charged tungstate and protonated ethylenediamine (EDA) to create a special local reductive environment in a non-reductive aqueous solution, which contributes to the in situ reduction of some of the hexavalent tungsten atoms during the 1D growth process and the mixed-valent nature of the final HTB structure. The as-prepared HTB nanomaterials are characterized to be highly crystalline and of uniform 1D morphology. Influences of synthetic conditions, such as the pH value, reaction time, temperature and amount of EDA, are systematically investigated. Meanwhile, this strategy is successfully introduced to prepare a series of metal-doped 1D HTB nanomaterials by simply changing the type of starting alkali tungstate. Experimental evidence reveals that the formation of the products follows an electrostatic-induced reductive nucleation–dissolution–recrystallization process, and the electrostatic interaction between the two oppositely charged species plays an indispensable role in the growth of mixed-valent HTB nanostructures. More importantly, these nanomaterials show efficient transformation of near-infrared light into local heat, indicating their potential applications as a new genre of functional materials in photothermal energy conversion as well as other relevant criteria.
Co-reporter:Qingbin Wu;Yani Yan;Qian Zhang;Jinhua Lu;Zhijian Yang; Yahong Zhang ; Yi Tang
ChemSusChem 2013 Volume 6( Issue 5) pp:820-825
Publication Date(Web):
DOI:10.1002/cssc.201300004
Abstract
A simple and efficient microwave-assisted HNb3O8 catalytic process is proposed for the dehydration of carbohydrates in the aqueous phase. A 5-hydroxymethylfurfural (HMF) yield of 55.9 % was achieved at a high substrate/catalyst weight ratio of 50 from a 10 wt % fructose solution, which is close to the yield achieved by homogeneous aqueous systems. The critical factor for this performance is the fast in situ exfoliation of layered HNb3O8 with the aid of microwave irradiation, which leads to quasi-homogeneous catalytic behavior. Importantly, the catalytic system is also applicable for the one-pot production of HMF from di- and polysaccharides, such as inulin, through a consecutive hydrolysis–dehydration reaction. Additionally, the unique restacking feature of the exfoliated HNb3O8 ensures the good reusability of the catalyst.
Co-reporter:Hongbin Zhang;Kunshan Song;Lei Wang;Hongxia Zhang; Yahong Zhang ; Yi Tang
ChemCatChem 2013 Volume 5( Issue 10) pp:2874-2878
Publication Date(Web):
DOI:10.1002/cctc.201300242
Co-reporter:Qingsheng Gao, Sinong Wang, Haocheng Fang, Jingwei Weng, Yahong Zhang, Jianjiang Mao and Yi Tang
Journal of Materials Chemistry A 2012 vol. 22(Issue 11) pp:4709-4715
Publication Date(Web):26 Jan 2012
DOI:10.1039/C2JM15443A
The diverse structures of molybdate anions significantly provide new opportunities to design various nanostructures of MoOx-based organic–inorganic hybrids with prominent catalytic, electrochemical and photo/electrochromic properties. In this paper, the one-dimensional (1D) growth originating from anisotropic molybdate anions is successfully introduced to prepare a series of hybrid nanowires of Mo3O10(C6H8N)2·2H2O (anilinium trimolybdate), Mo3O10(C2H10N2) (ethylenediamine trimolybdate) and Mo3O10(C5H6N)2·H2O (pyridium trimolybdate). Taking Mo3O10(C6H8N)2·2H2O for example, the 1D growth is proved to be associated with the chain-like structure of Mo3O102− anions by both experiments and quantum chemical calculations. Meanwhile, the synthesis parameters, e.g., reacting time, pH conditions and feeding ratio, show obvious influences on product morphologies based on different molybdate anions, further validating the growth mechanism. More importantly, the as-obtained MoOx/amine nanostructures remarkably exhibit tunable photochromic properties depending on their 1D structures and hybrid composites, which presents the potential to design well-tailored functional optical nanodevices.
Co-reporter:Chao Sun, Yisu Yang, Junming Du, Feng Qin, Zhipan Liu, Wei Shen, Hualong Xu and Yi Tang
Chemical Communications 2012 vol. 48(Issue 46) pp:5787-5789
Publication Date(Web):17 Apr 2012
DOI:10.1039/C2CC30607G
A novel route for anti-deactivation of methanol-to-propylene catalyst has been established through supporting nano-gold on ZSM-5, which efficiently reinforces the catalytic stability due to the effect of gold nanoparticles on the stabilization of dehydrogenation intermediates within the coking process.
Co-reporter:Jing Shi, Lifeng Chen, Nan Ren, Yahong Zhang and Yi Tang
Chemical Communications 2012 vol. 48(Issue 68) pp:8583-8585
Publication Date(Web):02 Jul 2012
DOI:10.1039/C2CC33701K
A zeolitic platinum-encapsulated microcapsule was successfully employed in the one-pot tandem synthesis of hydrazone directly from cyclohexanol with high conversion, selectivity and reusability due to the promising protection of the zeolitic shell around the catalyst.
Co-reporter:Sinong Wang;Dr. Qingsheng Gao;Dr. Yahong Zhang;Jing Gao;Dr. Xuhui Sun;Dr. Yi Tang
Chemistry - A European Journal 2011 Volume 17( Issue 5) pp:
Publication Date(Web):
DOI:10.1002/chem.201190019
Co-reporter:Sinong Wang;Dr. Qingsheng Gao;Dr. Yahong Zhang;Jing Gao;Dr. Xuhui Sun;Dr. Yi Tang
Chemistry - A European Journal 2011 Volume 17( Issue 5) pp:1465-1472
Publication Date(Web):
DOI:10.1002/chem.201002750
Abstract
A novel chemical oxidative polymerization approach has been proposed for the controllable preparation of organic–inorganic hybrid MoOx/polyaniline (PANI) nanocomposites based on the nanowire precursor of Mo3O10(C6H8N)2⋅2 H2O with sub-nanometer periodic structures. The nanotubes, nanowires, and rambutan-like nanoparticles of MoOx/PANI were successfully obtained through simply modulating the pH values to 2.5–3.5, ≈2.0 and ≈1.0, respectively. Through systematic physicochemical characterization, such as scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and so forth, the composition and structure of MoOx/PANI hybrid nanocomposites are well confirmed. It is found that the nanowire morphology of the precursor is the key to achieve the one-dimensional (1D) structures of final products. A new polymerization–dissolution mechanism is proposed to explain the formation of such products with different morphologies, in which the match between polymerization and dissolution processes of the precursor plays the important role. This approach will find a new way to controllably prepare various organic–inorganic hybrid 1D nanomaterials especially for polymer–hybrid nanostructures.
Co-reporter:Qingsheng Gao, Lichun Yang, Xinchun Lu, Jianjiang Mao, Yahong Zhang, Yuping Wu and Yi Tang
Journal of Materials Chemistry A 2010 vol. 20(Issue 14) pp:2807-2812
Publication Date(Web):12 Feb 2010
DOI:10.1039/B921001F
This paper presents a novel strategy to synthesize MoO2/carbon nanowires based on organic–inorganic hybrid nanocomposites with nanometre periodic structures. The organic–inorganic hybrid precursors provide uniform reactions throughout the composites for achieving novel carbon-hybrid structures and nano-morphology via easy calcination. Through the systematic physical characterization including scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, etc., the one-dimensional and carbon-hybrid structure of MoO2/C nanowires was confirmed. This synthetic strategy is also proved universal for other novel MoO2/C nanostructures based on various organic-inorganic hybrid precursors. Furthermore, the MoO2/C hybrid nanowires show good rate capability even at the high current density of 1000 mA g−1 as anode material for lithium ion battery.
Co-reporter:Chao Sun, Junming Du, Jian Liu, Yisu Yang, Nan Ren, Wei Shen, Hualong Xu and Yi Tang
Chemical Communications 2010 vol. 46(Issue 15) pp:2671-2673
Publication Date(Web):23 Feb 2010
DOI:10.1039/B925850G
A novel route is proposed for the preparation of mesopore containing zeolite ZSM-5 via in situ hydrothermal treatment of a solution containing alkali-dissolved SBA-15 containing carbonized surfactant P123 in the mesopores; it exhibited prominent stability enhancement for methanol to propylene reaction.
Co-reporter:Qingsheng Gao, Chenxi Zhang, Sinong Wang, Wei Shen, Yahong Zhang, Hualong Xu and Yi Tang
Chemical Communications 2010 vol. 46(Issue 35) pp:6494-6496
Publication Date(Web):09 Aug 2010
DOI:10.1039/C0CC01430C
An effective and safe route is proposed to prepare supported Mo2C-based catalysts from organic–inorganic hybrids, which exhibit high activity and stability for producing H2 from methanol catalytic decomposition.
Co-reporter:Yuanyuan Hu, Yahong Zhang and Yi Tang
Chemical Communications 2010 vol. 46(Issue 22) pp:3875-3877
Publication Date(Web):05 May 2010
DOI:10.1039/C002551H
Zeolite nanoparticles with various organosilanized surfaces have been synthesized in situ by a one-step approach which provides not only a functionalized surface for diverse host–guest interactions but also an attractive path for preparation of monodispersed template-free zeolite nanoparticles.
Co-reporter:L.C. Yang, Q.S. Gao, L. Li, Y. Tang, Y.P. Wu
Electrochemistry Communications 2010 Volume 12(Issue 3) pp:418-421
Publication Date(Web):March 2010
DOI:10.1016/j.elecom.2010.01.008
Mesoporous Ge was prepared by mechanochemical reaction of GeO2 and Mg powders followed by an etching process with HCl solution. It was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and charge–discharge measurement. With a pore-distribution concentrated around 10 nm, the product presents a BET surface area of 49.98 m2/g. When using as an anode material for lithium ion battery, the mesoporous Ge exhibits a reversible capacity of 950 mA h/g and retains a capacity of 789 mA h/g after 20 cycles at a current density of 150 mA/g. The cycleability is significantly improved compared with non-porous Ge.
Co-reporter:Deju Wang, Xueli Li, Zhongneng Liu, Yahong Zhang, Zaiku Xie, Yi Tang
Journal of Colloid and Interface Science 2010 Volume 350(Issue 1) pp:290-294
Publication Date(Web):1 October 2010
DOI:10.1016/j.jcis.2010.05.065
Hierarchical structured ZSM-5 zeolite of c-axis-oriented nanorods has been prepared by a zeolite-seed-assisted hydrothermal synthesis method without any type of mesoscale template. The final product has loose aggregation which consists of rod-like nanocrystals with widths of about 20–30 nm, formed by the oriented aggregation model. The nitrogen physisorption suggested that the hierarchical structured ZSM-5 zeolite had higher mesopore volume and external surface area than the sample prepared conventionally. Due to the shortened microporous channel and opening mesopore, the prepared HZSM-5 catalyst presents high catalytic activity and stability for the alkylation of phenol with isopropanol.Graphical abstractHierarchical structured ZSM-5 zeolite of oriented nanorods was prepared by zeolite-seed-assisted hydrothermal synthesis without adding mesoscale template; it presents high catalytic activity and stability for phenol alkylation.Research highlights► ZSM-5 zeolite of nanorods is synthesized hydrothermally by a seed-assisted method. ► ZSM-5 zeolite of aligned nanorods is formed by the oriented aggregation mechanism. ► ZSM-5 zeolite of nanorods brings benefits to the diffusion in catalytic conversions.
Co-reporter:Nan Ren, Zhi-Jian Yang, Xin-Chun Lv, Jing Shi, Ya-Hong Zhang, Yi Tang
Microporous and Mesoporous Materials 2010 Volume 131(1–3) pp:103-114
Publication Date(Web):June 2010
DOI:10.1016/j.micromeso.2009.12.009
A method based on seed surface crystallization (SSC) mechanism has been proposed for facile, rapid, controllable and low-cost synthesis of ZSM-5 zeolite with submicron-size and interesting core–shell structure. The crystallization process of the ZSM-5 zeolite with all sizes can be accomplished within 2.5 h. The morphology and size of zeolite ZSM-5 products can both be facilely adjustable in the domain of 270–1100 nm depending upon the characters of silicalite-1 seeds, while the thickness of aluminum-containing zeolite ZSM-5 shells can be well tuned by changing the amount of silicalite-1 seed. More interestingly, the siliceous silicalite-1 seeds within the obtained zeolite crystals could be selectively removed by alkaline treatment. By systematically tracking the crystallization process combined with mathematical analysis, the crystallization of ZSM-5 zeolites in the reaction system is revealed as SSC mechanism with a size-independent, linear growth process. Their crystal growth rate is calculated as c.a. 0.15 μm h−1 regardless of the seed size and amount.
Co-reporter:Jing Shi, Nan Ren, Ya-Hong Zhang, Yi Tang
Microporous and Mesoporous Materials 2010 Volume 132(1–2) pp:181-187
Publication Date(Web):July 2010
DOI:10.1016/j.micromeso.2010.02.018
In the present work, the detailed formation process of hollow silicalite-1 microcapsules (HSMs) was investigated in the hydrothermal system of silicalite-1 pre-seeded mesoporous silica spheres (MSSs). The effects of the starting gel composition together with the hydrothermal synthesis conditions such as alkalinity, tetra-propylammonium cation (TPA+) content, and temperature on the features of microcapsules are comprehensively discussed, and a related mechanism is presented. It is found that the matching of core dissolution rate (Rcd) and silicalite-1 shell inter-growth rate (Rsi) is crucial for the formation of perfect HSMs. The proper addition of tetraethoxy-orthosilane (TEOS) as supplemental silica source could accelerate Rsi whereas excess TEOS will dramatically suppress the consumption of siliceous species from the MSS cores owing to the higher activity of siliceous species in TEOS for the zeolite crystallization. The excellent HSMs with dense inter-grown shell structure as well as perfect hollow center can be fabricated by controlling the relative rates of the dissolution of silica template core and the formation of zeolitic shell.
Co-reporter:Deju Wang, Zhongneng Liu, Hui Wang, Zaiku Xie, Yi Tang
Microporous and Mesoporous Materials 2010 Volume 132(Issue 3) pp:428-434
Publication Date(Web):August 2010
DOI:10.1016/j.micromeso.2010.03.023
Columned ZSM-5 zeolite monoliths with hierarchical structure and excellent mechanical strength were successfully prepared by a hydrothermal transformation method. The pre-formed extrudates of aluminosilicate embedded with β zeolite were subjected to a hydrothermal synthesis system and the hierarchical porous ZSM-5 zeolite monoliths with the same columned shape were obtained after the hydrothermal treatment. The intra-particle hollow structure formed during hydrothermal synthesis was attributed to the digestion of inner β zeolite accompanying with the growth of ZSM-5 zeolite shell. The related data of X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) analysis, N2-sorption experiment and mercury intrusion prosimetry (MIP), showed ZSM-5 zeolite monolith had enriched multi-porosity and excellent mechanical stability, which contribute to its further application in field of catalysis and separation. The obtained hierarchical ZSM-5 zeolite monoliths showed superior catalytic performance in α-pinene isomerization for their proper acidity and good diffusion, compared with the ZSM-5 zeolite sample prepared from the precursor without β zeolite.
Co-reporter:Junkai Hu, Wei Shan, Weijia Zhang, Yahong Zhang, Yi Tang
Microporous and Mesoporous Materials 2010 Volume 129(1–2) pp:210-219
Publication Date(Web):1 April 2010
DOI:10.1016/j.micromeso.2009.09.017
The preparation and mechanism investigation of mesoporosity and morphology are extremely important in the field of mesoporous materials. By using neutral amines as templates and alcohols as co-solvents, a series of HMS with different morphologies and mesoporosities are obtained. When long alkyl chain surfactant (n ⩾ 16) and short alkyl chain alcohol (CH3OH and C2H5OH) are employed, the increasing alcohol content induces the morphological transformation from lotus-leaf-like flake, to aggregated flake, potato-like vesicle, sphere, and finally to solid nanoparticle. When using short alkyl chain surfactant (n ⩽ 14) and long alkyl chain alcohol (C3H7OH), hollow vesicle, cracked sphere, sphere and mesoporous nanoparticle are successively obtained with the increase of alcohol content. Compared with the conventional mesoporous materials, HMS with these special morphologies has a unique regionally distributed dual meso-structure. By systematically analyzing the effects of co-solvent and surfactant, it is found that the morphology of the product is mainly determined by the initial surfactant micelle which can be adjusted by the type and concentration of surfactant and alcohol. Moreover, with progress of reaction, the decrease of surfactant concentration and the increase of silica polymerization degree would induce the mesophase evolution of product from 2D lamella-like to 3D wormholelike meso-structures, leading to the formation of dual meso-structured HMS products. The understanding of these processes is helpful for preparing mesoporous materials with various morphology and meso-structure for catalysis, separation and other application fields.
Co-reporter:Qingsheng Gao, Chenxi Zhang, Songhai Xie, Weiming Hua, Yahong Zhang, Nan Ren, Hualong Xu and Yi Tang
Chemistry of Materials 2009 Volume 21(Issue 23) pp:5560
Publication Date(Web):November 5, 2009
DOI:10.1021/cm9014578
Co-reporter:You-Hao Yang, Nan Ren, Ya-Hong Zhang, Yi Tang
Journal of Photochemistry and Photobiology A: Chemistry 2009 Volume 201(2–3) pp:111-120
Publication Date(Web):25 January 2009
DOI:10.1016/j.jphotochem.2008.10.012
An unusually stable and regeneratable nanosized CdS-based catalyst for visible-light-induced photocatalysis was developed by combining the protection effect of polyelectrolyte and the spatial confinement of mesopores. This catalyst was fabricated by coating a layer of poly(diallyl dimethylammonium) chloride (PDDA) around nanosized CdS pre-incorporated hexagonal mesoporous silica (HMS) sphere, and named as CdS/HMS–PDDA. In contrast to the catalyst without PDDA-coating (CdS/HMS), which loses its activity at 3rd run, CdS/HMS–PDDA can completely degrade the organic pollutants for over 22 runs. Noticeably, CdS/HMS–PDDA can be facilely regenerated by H2S treatment, and the catalyst shows the same capability as the fresh one even after 6 regenerations (accumulatively 151 runs). No cadmium leakage is detected from CdS/HMS–PDDA during the photocatalytic processes, promising its environmental compatibility. A series of characterization experiments reveal that the polyelectrolyte layer effectively prevents the cadmium species from leakage, and further delays the photocorrosion of CdS via a back reaction occurred by use of photogenerated electrons remaining in CdS, endowing the catalyst with high stability and regeneratability.
Co-reporter:Yuan-Yuan Hu, Ya-Hong Zhang, Nan Ren and Yi Tang
The Journal of Physical Chemistry C 2009 Volume 113(Issue 42) pp:18040-18046
Publication Date(Web):September 24, 2009
DOI:10.1021/jp903989p
In this study, nanozeolites LTL with different exposed crystal planes and sizes were synthesized as excellent model material to study the effects of the crystal plane and size of the nanozeolite on the protein adsorption behaviors. A larger protein adsorption amount is observed on the smaller nanocrystals due to their larger surface area. More importantly, it is found that the (001) crystal plane with a 12-membered ring channel array has a larger contribution for protein adsorption on zeolite LTL nanocrystals than the other two dimensions with a very small pore opening (1.5 Å). It is proposed that the difference of protein adsorption on various crystal planes could be attributed to abundant exposed pore openings on the top (bottom) surface and curved surface of the side surface in columned nanozeolites LTL. This fact shows that the nanoscaled topography is also an important factor determining protein adsorption on the surface of nanozeolites, and efforts in the future should be focused on the synthesis of nanozeolites LTL with abundant exposed (001) planes. This observation will provide a new view for bioapplication and design of crystalline nanomaterials.
Co-reporter:Weijia Zhang, Ping Chen, Qingsheng Gao, Yahong Zhang and Yi Tang
Chemistry of Materials 2008 Volume 20(Issue 5) pp:1699
Publication Date(Web):February 5, 2008
DOI:10.1021/cm7022554
A steel-assisted polyol method has been proposed for the preparation of Ag nanowires (AgNWs) at high AgNO3 concentrations of up to 0.5 M. The average diameter of products could be adjusted from approximately 100 to 300 nm by increasing the synthetic concentration. It was found that in situ nitric acidic etching was a fatal factor for the stability of the multiply twinned particles (MTPs), which were the seeds of AgNWs in the polyol synthesis system. The introduction of stainless steel could effectively consume the in situ generated nitric acid through a corrosion reaction between them, hence enabling the survival of MTPs for the consequent growth of AgNWs.
Co-reporter:Chenxi Zhang, Ping Chen, Jian Liu, Yahong Zhang, Wei Shen, Hualong Xu and Yi Tang
Chemical Communications 2008 (Issue 28) pp:3290-3292
Publication Date(Web):16 Jun 2008
DOI:10.1039/B807354F
A novel catalyst of silver microparticles embedded in a silicon nanowire array support (Ag@SiNW) was prepared by an in situ electroless metal deposition method; it exhibited high selectivity and stability for gas-phase oxidation of high alcohol to its corresponding aldehyde.
Co-reporter:Jianchao Xia, Dongsen Mao, Weichuan Tao, Qingling Chen, Yahong Zhang, Yi Tang
Microporous and Mesoporous Materials 2006 Volume 91(1–3) pp:33-39
Publication Date(Web):15 April 2006
DOI:10.1016/j.micromeso.2005.11.014
A series of MCM-22 zeolites were prepared by hydrothermal synthesis and subsequent dealumination by oxalic/citric acid leaching and steaming. The structural and acidic properties of the prepared samples were characterized by methods of XRD, ICP-AES, 27Al MAS NMR, pyridine-adsorbed IR and NH3-TPD. The results indicated that the sample treated by oxalic acid (MCM-22O) has the lowest aluminum content while the samples treated by steam have little change of the aluminum content. Unusually, sample MCM-22O possessed the strongest acidity among the dealuminated samples in spite of its lowest content of aluminum. It may be due to its least content of extraframework aluminum, which may lead to the weakening of acidity. Additionally, the prepared zeolites were mixed with a methanol synthesis catalyst and then applied in the process of syngas to dimethyl ether. Citric acid treated sample performed best with the least generation of byproducts, which have been well related to its structural and acidic properties.
Co-reporter:Bo Wang;Cheng Chi;Wei Shan;Yahong Zhang Dr.;Nan Ren;Wuli Yang Dr.
Angewandte Chemie 2006 Volume 118(Issue 13) pp:
Publication Date(Web):24 FEB 2006
DOI:10.1002/ange.200504191
Chiralität auf der Streckbank: Chirale mesostrukturierte MCM-41-Siliciumoxid-Nanofasern (siehe TEM-Bild, die Pfeile zeigen sich wiederholende Einheiten an) mit einer oder zwei Drehachsen sind die Produkte einer einfachen Verdünnungssynthese ohne chirale Additive. Eine kontinuierliche Transformation von einer chiralen Mesostruktur in eine gestreckte achirale Mesostruktur wurde beobachtet.
Co-reporter:Tao Yu;Yahong Zhang Dr.;Chunping You;Jihua Zhuang;Bo Wang;Baohong Liu ;Yijin Kang
Chemistry - A European Journal 2006 Volume 12(Issue 4) pp:
Publication Date(Web):26 OCT 2005
DOI:10.1002/chem.200500562
An enzyme-immobilized nanozeolite-assembled electrode was prepared by controlled assembly of nanometer-sized Linder type-L zeolite (nano-LTL-zeolite) on an indium tin oxide (ITO) glass electrode surface, and subsequent immobilization of cytochrome c. Cyclic voltammetric (CV) and amperometric experiments showed that, relative to other reported electrodes, the enzyme-immobilized electrodes possess fast electron-transfer rates (2.2 s−1), a broad linear range (15–540 μmol L−1), a low detection limit (3.2 nmol L−1), a remarkably long lifetime (5 months), and high stability in the pH range 5–10. These characteristics could be due to the fact that nanozeolites assembled on ITO have high immobilization ability and facilitate interaction with enzymes. The function controllability of these enzyme electrodes, resulting from the facile manipulability of nanozeolite-assembled layers, may provide a possibility to rationally design biosensors.
Co-reporter:Bo Wang, Cheng Chi, Wei Shan, Yahong Zhang, Nan Ren, Wuli Yang,Yi Tang
Angewandte Chemie International Edition 2006 45(13) pp:2088-2090
Publication Date(Web):
DOI:10.1002/anie.200504191
Co-reporter:B. Wang;W. Shan;Y. Zhang;J. Xia;W. Yang;Z. Gao;Y. Tang
Advanced Materials 2005 Volume 17(Issue 5) pp:
Publication Date(Web):3 MAR 2005
DOI:10.1002/adma.200401574
The micrometer-scale self-assembly behaviour of MCM-41-type mesostructured silica is revealed through the study of a family of vesicular mesostructured silica with topology genus from 1 to 0 (see Figure and inside cover). The topological transformation and assembly kinetics demonstrate that the formation of the vesicular structure is closely correlated with the properties of the cetyltrimethylammonium–silicate building block and the hydrophobic nature of the ester additive.
Co-reporter:B. Wang;W. Shan;Y. Zhang;J. Xia;W. Yang;Z. Gao;Y. Tang
Advanced Materials 2005 Volume 17(Issue 5) pp:
Publication Date(Web):3 MAR 2005
DOI:10.1002/adma.200590027
The micrometer-scale self-assembly behavior of MCM-41-type mesostructured silica is shown by Tang and co-workers on p. 578 through study of a family of vesicular mesostructured silica with topology genera from 1 to 0. The inside cover shows a series of typical vesicular structures with different topologies on the micrometer scale. A better understanding of the micrometer-scale self-assembly behavior provides a guide for the rational design of new hierarchical organic–inorganic composite materials, and may also shed new light on the natural biosilicification process.
Co-reporter:Wei Shan, Bo Wang, Yahong Zhang and Yi Tang
Chemical Communications 2005 (Issue 14) pp:1877-1879
Publication Date(Web):11 Feb 2005
DOI:10.1039/B418006B
Lotus-leaf-like silica flakes with a three-dimensionally (3D) connected nanoporous structure and controllable thickness have been facilely synthesized; the flakes produced exhibited superior performance in adsorbing enzymes to their microspheric analogues.
Co-reporter:Deju Wang, Guibo Zhu, Yahong Zhang, Wuli Yang, Biyun Wu, Yi Tang and Zaiku Xie
New Journal of Chemistry 2005 vol. 29(Issue 2) pp:272-274
Publication Date(Web):18 Jan 2005
DOI:10.1039/B414127J
Controlled release and conversion of guest species (CO2) in zeolite microcapsules was achieved thanks to the high microporosity and the thermal and chemical stability of the zeolite shells.
Co-reporter:Yahong Zhang Dr.;Xiaoyan Wang Dr.;Wei Shan;Biyun Wu;Huizhi Fan Dr.;Xijuan Yu Dr. ;Pengyuan Yang
Angewandte Chemie 2005 Volume 117(Issue 4) pp:
Publication Date(Web):13 DEC 2004
DOI:10.1002/ange.200460741
Konzentration! Zeolith-Nanokristalle verbessern die Effizienz eines Entsalzungsschritts, sodass in geringer Menge vorliegende Proteine angereichert und problemlos MALDI-TOF-massenspektrometrisch detektiert werden können (siehe Bild). Wegen deutlich höherer Signal-Rausch-Verhältnisse für viele Peptide ist diese Methode interessant für Anwendungen in der Proteomik.
Co-reporter:Yahong Zhang Dr.;Xiaoyan Wang Dr.;Wei Shan;Biyun Wu;Huizhi Fan Dr.;Xijuan Yu Dr. ;Pengyuan Yang
Angewandte Chemie International Edition 2005 Volume 44(Issue 4) pp:
Publication Date(Web):13 DEC 2004
DOI:10.1002/anie.200460741
Concentrated efforts: A zeolite-nanocrystal-mediated enrichment procedure that doubles as a desalting step allows low-abundance proteins to be readily detected with MALDI-TOF MS (see picture). Mass spectral signal-to-noise ratios are greatly improved for a wide range of peptides, which underscores the potential of this procedure to boost proteomics research.
Co-reporter:Nan Ren, An-Gang Dong, Wen-Bin Cai, Ya-Hong Zhang, Wu-Li Yang, Sheng-Juan Huo, Ying Chen, Song-Hai Xie, Zi Gao and Yi Tang
Journal of Materials Chemistry A 2004 vol. 14(Issue 24) pp:3548-3552
Publication Date(Web):29 Sep 2004
DOI:10.1039/B411669K
A versatile peripheral-pore-nanocasting method is employed to fabricate a series of novel microcapsules with mesoporous shell of noble metal or noble metal oxides, including Pt, PdO, RuO2 and IrO2. The shell thickness of these hollow microcapsules can be adjusted by controlling the depth of 3-amino-propyltriethoxysilane (APS) modification. By pre-filling the guest species or their precursors into the 3-D pores of HMS (hexagonal mesoporous molecular sieves) spheres, an interesting material with a “sphere in shell” structure could be fabricated via the same method. Both the mesoporous platinum hollow microcapsules and carbon spheres encapsulated in platinum microcapsules have shown high mass-normalized activities as a catalyst in the oxidation of methanol, a fundemantal reaction in direct methanol fuel cells (DMFC).
Co-reporter:Jiang Shen, Wei Shan, Yahong Zhang, Junming Du, Hualong Xu, Kangnian Fan, Wei Shen and Yi Tang
Chemical Communications 2004 (Issue 24) pp:2880-2881
Publication Date(Web):15 Nov 2004
DOI:10.1039/B412986E
A novel catalyst of silver nanoparticles over a zeolite film-coated copper grid (SZFC) has been fabricated via an in situ electrolytic method; it exhibited high catalytic activity and selectivity at a relatively low temperature for the partial oxidation of 1,2-propylene glycol to methyl glyoxal.
Co-reporter:Yahong Zhang, Xijuan Yu, Xiaoyan Wang, Wei Shan, Pengyuan Yang and Yi Tang
Chemical Communications 2004 (Issue 24) pp:2882-2883
Publication Date(Web):25 Oct 2004
DOI:10.1039/B411336E
Metal-ion-immobilized zeolite nanoparticles have been applied for the first time to isolate phosphopeptides from tryptic β-casein digest; the phosphopeptides enriched on the modified zeolite nanoparticles could be effectively identified by MALDI-TOF-MS/MS.
Co-reporter:Wei Shan, Yahong Zhang, Wuli Yang, Chen Ke, Zi Gao, Yunfen Ye, Yi Tang
Microporous and Mesoporous Materials 2004 Volume 69(1–2) pp:35-42
Publication Date(Web):8 April 2004
DOI:10.1016/j.micromeso.2004.01.003
Thin zeolite films with thicknesses from several hundred nanometers to a few micrometers have been fabricated through electrophoretic deposition (EPD) in acetylacetone (Acac) and/or isopropyl alcohol (IPA). Various types of nanosized zeolites with different Si/Al ratios ranging from 1.6 (zeolite LTA) to nearly infinity (silicalite-1) were applied to prepare the EPD suspensions and showed different behaviors in EPD. The EPD rate of zeolite particles in non-aqueous medium was much higher than that in aqueous system mainly due to the high voltage applied, and consequently the whole process was usually completed in a few seconds. It was found that the Al/(Si + Al) ratios of zeolites and the chemical/physical properties of the EPD medium were two crucial factors which affected the thickness and density of the zeolite films prepared by EPD. The zeolite films fabricated through EPD could be effectively densified by secondary growth to prepare compact zeolite membranes.
Co-reporter:A. Dong;N. Ren;W. Yang;Y. Wang;Y. Zhang;D. Wang;J. Hu;Z. Gao;Y. Tang
Advanced Functional Materials 2003 Volume 13(Issue 12) pp:
Publication Date(Web):17 NOV 2003
DOI:10.1002/adfm.200304405
A novel and flexible strategy involving hydrothermal transformation of guest-incorporated zeolite-seeded mesoporous silica spheres was proposed to prepare guest-encapsulated hollow zeolite spheres and three-dimensionally (3D) ordered macroporous zeolite monoliths. The guest species that were pre-incorporated into the mesopores of silica spheres could be spontaneously encapsulated inside the formed hollow zeolite shells by consuming silica nutrition of the original mesoporous silica cores during the hydrothermal process. A wide range of guest materials with a size ranging from nanometers to micrometers, e.g., Ag and PdO nanoparticles, and mesoporous spheres of carbon and polymer of micrometer size were successfully encapsulated into both discrete hollow zeolite spheres and 3D ordered macroporous zeolite monoliths. Such materials are expected to find a variety of applications such as catalysis, adsorption, and novel microreactors for their special structures with active species inside and zeolitic porous shell outside.
Co-reporter:Angang Dong, Yajun Wang, Deju Wang, Wuli Yang, Yahong Zhang, Nan Ren, Zi Gao, Yi Tang
Microporous and Mesoporous Materials 2003 Volume 64(1–3) pp:69-81
Publication Date(Web):3 October 2003
DOI:10.1016/S1387-1811(03)00484-0
Hollow zeolite microcapsules with spherical and various non-spherical shapes were fabricated through a novel strategy involving the crystallization of mesoporous silica (MS) particles. This conversion process was achieved by vapor phase transport treatment of MS particles which were pre-seeded by nanozeolite via the electrostatic assembly technique. The capsule shell was composed of closed packed zeolite crystals growing from the initial seeds by consuming the silica “nutrition” in the internal MS cores. The effects of seed size and seed type on the transformation of MS particles were investigated in detail. More importantly, guest species (e.g. Fe2O3 and Ag nanoparticles) which had been incorporated in the mesopores of the MS particles could be spontaneously encapsulated inside the generated capsules during the MS consumption process, thus, hollow zeolite capsules with functionalized interiors could be easily fabricated.
Co-reporter:Yahong Zhang, Fei Chen, Wei Shan, Jihua Zhuang, Angang Dong, Wenbin Cai, Yi Tang
Microporous and Mesoporous Materials 2003 Volume 65(2–3) pp:277-285
Publication Date(Web):4 November 2003
DOI:10.1016/j.micromeso.2003.08.012
Ultrathin nanozeolite films were prepared on the surface of Pt and glass carbon electrodes using nanoscale zeolite particles as building block via a layer-by-layer (LbL) technique or by a secondary growth method. Compared to conventional zeolite-modified electrodes, the nanozeolite film modified ones (nanoZMEs) prepared by these methods exhibit good membrane morphologies with controllable thickness in nanometer scale and large zeolite/electrode contact areas due to the nanoscale zeolite film attached directly to the electrode. Ag+, Cd2+ and Pb2+ were selected as examples to evaluate the electrochemical performance of nanoZMEs with designed thickness. With the same thickness of zeolite layer, nanoZMEs prepared by the LbL technique possess short preconcentration and response time, while nanoZMEs fabricated through the secondary growth method exhibit high accumulation ability and ion exchange selectivity. It is found that besides the inherent ion exchange selectivity of the zeolite layer, the transport rate of ions in the zeolite layer toward the electrode surface is an important factor that affected the electrochemical selectivity of the ZMEs.
Co-reporter:Y. Wang;Y. Tang;A. Dong;X. Wang;N. Ren;W. Shan;Z. Gao
Advanced Materials 2002 Volume 14(Issue 13‐14) pp:
Publication Date(Web):1 JUL 2002
DOI:10.1002/1521-4095(20020705)14:13/14<994::AID-ADMA994>3.0.CO;2-9
Co-reporter:C. Ke, W. L. Yang, Z. Ni, Y. J. Wang, Y. Tang, Y. Gu and Z. Gao
Chemical Communications 2001 (Issue 8) pp:783-784
Publication Date(Web):03 Apr 2001
DOI:10.1039/B010197O
Zeolite coated fibers with compact and full deposits have been
fabricated by electrophoretic deposition of nanozeolites onto carbon
fibers, whereafter hollow zeolite fibers have been obtained by calcination
to remove the substrates.
Co-reporter:X. D. Wang, W. L. Yang, Y. Tang, Y. J. Wang, S. K. Fu and Z. Gao
Chemical Communications 2000 (Issue 21) pp:2161-2162
Publication Date(Web):19 Oct 2000
DOI:10.1039/B006539K
Hollow spheres of zeolite have been fabricated through a
layer-by-layer technique using polystyrene spheres as templates and
nanozeolites as ‘building blocks’, followed by calcination.
Co-reporter:Hongbin Zhang, Yuchun Ma, Kunshan Song, Yahong Zhang, Yi Tang
Journal of Catalysis (March 2014) Volume 311() pp:
Publication Date(Web):1 March 2014
DOI:10.1016/j.jcat.2013.11.022
Co-reporter:Kunshan Song, Hongbin Zhang, Yahong Zhang, Yi Tang, Kangjian Tang
Journal of Catalysis (March 2013) Volume 299() pp:119-128
Publication Date(Web):1 March 2013
DOI:10.1016/j.jcat.2012.11.011
WOx/ZrO2 nanosized catalysts with high dispersion threshold were prepared via a novel two-phase interface hydrolysis (TPIH) method and characterized by N2 physisorption, X-ray diffraction, transmission electron microscopy, UV–vis diffuse reflectance spectroscopy, Raman spectroscopy, and potentiometric titration with n-butylamine. It was found that the WOx/ZrO2 nanosized catalyst prepared by TPIH possessed a higher dispersion threshold (ca. 0.372 g WOx/g ZrO2) than that obtained by a conventional impregnation method, due to its higher specific surface area of 114 m2/g and tungsten surface density (6.2 W atoms/nm2). Significantly, the catalyst at dispersion threshold by TPIH has a remarkable number of strong acid sites with E > 400 mV and nearly double catalytic activity for n-pentane isomerization compared to that prepared by a conventional impregnation method. When this is combined with the results of spectral characterization, the high activity of the catalysts obtained by TPIH is ascribed to the abundant strong acidic polytungstate species on ZrO2 at their dispersion threshold. Challenges for future work would be developing the TPIH method with supports and exploring reaction conditions to reduce coke formation.Graphical abstractThe WOx/ZrO2 catalysts prepared by the two-phase interface hydrolysis method possess much more polytungstate species with strong acidity as a result of a higher WOx loading at dispersion threshold and double catalytic activity for the isomerization of n-pentane compared with that prepared by conventional impregnation method.Download high-res image (151KB)Download full-size imageHighlights► WOx/ZrO2 catalysts prepared by TPIH possess a higher surface and W surface density. ► The TPIH method can make WOx/ZrO2 catalysts achieve higher dispersion threshold. ► TPIH endows WOx/ZrO2 catalysts with double catalytic activity as impregnation method. ► Polytungstate species with E > 400 mV are suggested to be the active sites.
Co-reporter:Hongbin Zhang, Yuchun Ma, Kunshan Song, Yahong Zhang, Yi Tang
Journal of Catalysis (June 2013) Volume 302() pp:115-125
Publication Date(Web):1 June 2013
DOI:10.1016/j.jcat.2013.03.019
•Nano-crystallite oriented-assembled ZSM-5 zeolite is prepared by seed-induced route.•Morphology and external surface are regulated by co-effects of KF, template, and seed.•Crystallinity and intrinsic acidity are preserved when decreasing crystallite size.•Fine accessibility and high acid strength lead to notable LDPE cracking activity.•Fast and low-cost preparation opens a possibility for large-scale production.Nano-crystallite oriented self-assembled ZSM-5 zeolite (NS-Z5) is successfully synthesized with high yield of 85% by a facile salt-aided seed-induced method within 1.5 h at TPABr (tetrapropylammonium bromide)/SiO2 ratio of 0.1. The systematic and thorough characterizations, involving morphology, textural/structure property, and acidity, indicate that NS-Z5 particle is composed of oriented-assembled high-crystalline zeolite MFI nano-crystallites and possesses abundant accessible strong acid sites due to its large/rough external surface. The strong acidity of NS-Z5 sample results from its high crystallinity and few framework defects benefiting from the introduction of seeds. The catalytic evaluations both in batch and in thermogravimetric reactors demonstrate the important roles of the accessibility and strength of acid sites on low-density polypropylene cracking. This paper provides a facile method for preparation of hierarchical high-crystalline ZSM-5 nano-zeolite and confirms the significance to synchronously maintain large amount and high strength of accessible acid sites on large molecule conversion.Nano-crystallite oriented self-assembled ZSM-5 zeolite has been synthesized by a salt-aided seed-induced route; this catalyst exhibits notable activity of LDPE cracking reaction for the well maintaining fine accessibility and high strength of acid sites.Download high-res image (87KB)Download full-size image
Co-reporter:Jing Shi, Xiang Li, Quanrui Wang, Yahong Zhang, Yi Tang
Journal of Catalysis (July 2012) Volume 291() pp:87-94
Publication Date(Web):1 July 2012
DOI:10.1016/j.jcat.2012.04.008
The platinum-encapsulated zeolitically microcapsular catalyst, associated with the immobilized Candida antartica lipase B (Novozyme®435), is successfully employed in the dynamic kinetic resolution of phenylethylamine. A conversion of 80% and a selectivity of 95% are achieved, and negligible loss of activity is detected even after reaction of 5 runs. It is found that the existence of the silicalite-1 shell not only effectively prevents the deactivation of both enzyme and Pt by isolating them in different regions of reaction system, but also significantly reduces the formation of by-products on the Pt nanoparticles within the protected space of zeolitic microcapsule. Such features of zeolitic shell should further promote the designing of various catalysts for multistep reaction network.Graphical abstractPlatinum-encapsulated zeolitic microcapsules are successfully employed in dynamic kinetic resolution of phenylethylamine with high activity and selectivity due to promising protective effect of the zeolitically microcapsular structure.Download high-res image (109KB)Download full-size imageHighlights► Platinum-encapsulated ZMCs are successfully employed in DKR of phenylethylamine. ► ZMC structure of catalyst promises its activity, selectivity and reusability. ► Isolation effect of zeolitic shell prohibits the deactivation of Pt and enzyme. ► The protected space within ZMC limits the formation of by-product.
Co-reporter:Guoliang Zhao, Jiawei Teng, Zaiku Xie, Wenqing Jin, Weimin Yang, Qingling Chen, Yi Tang
Journal of Catalysis (15 May 2007) Volume 248(Issue 1) pp:29-37
Publication Date(Web):15 May 2007
DOI:10.1016/j.jcat.2007.02.027
A series of HZSM-5 catalysts with various phosphorus (P) loadings (0–2.1 wt%) were prepared by impregnation of phosphoric acid. The effect of phosphorus on the structure and acidity of HZSM-5 catalyst and its catalytic performance for C4-olefin cracking reactions were studied by XRD, N2 adsorption, NMR, NH3-TPD, FTIR spectra of adsorbed pyridine, TGA, and catalytic tests. The results revealed that the structure of HZSM-5 samples was scarcely damaged with increasing P loadings, whereas strong acidity of them was weakened mainly due to the dealumination of tetrahedral framework aluminum (TFAL) after P modification. The results of C4-olefin cracking reactions showed a great increment of the propylene selectivity for the P-modified HZSM-5 with the optimal propylene yield at a P-loading of 1.5 wt%. It was found that both coke deposition and dealumination were the crucial factors in the deactivation of HZSM-5. Due to the dealumination and thus elimination of part of the strong acid sites, P-modified HZSM-5 showed excellent anticoking ability. TFAL of P-modified HZSM-5 changed mainly to distorted tetrahedral aluminum (DTAL) or pentacoordinated aluminum (PAL) species in the process of C4-olefin cracking reaction, which can still act as stable active centers for C4-olefin cracking to produce propylene. Thus, P-modified HZSM-5 shows excellent stability. A possible reaction pathway for C4-olefin cracking reactions has been proposed based on the reaction results.
Co-reporter:Nan Ren, You-Hao Yang, Ya-Hong Zhang, Quan-Rui Wang, Yi Tang
Journal of Catalysis (15 February 2007) Volume 246(Issue 1) pp:215-222
Publication Date(Web):15 February 2007
DOI:10.1016/j.jcat.2006.11.028
A new strategy of heterogenizing homogeneous catalysts by encaging the quasi-homogeneous catalytic reaction into a zeolitic microcapsular reactor has been proposed. As an example toward achieving such goal, a highly stable, nanopalladium-entrapped zeolitic microcapsular reactor (Pd@S1) was successfully fabricated and evaluated for Heck coupling reaction. The Pd@S1 not only exhibits excellent reactivity at low Pd adoption (Pd/PhI=0.0025) during the reaction, but also can be reused for more than 10 runs with negligible loss of activity, in contrast to rapid decay of activity of conventional Pd/C catalysts. Such reusability can be explained by the encapsulation of the “quasi-homogeneous” reaction mechanism of Heck coupling within the micrometer-sized hollow cavities of Pd@S1, which successfully avoids the Pd leaching during the reaction. The strategy may be helpful in the design of reusable, highly efficient catalysts with advantages deriving from both homogeneous and heterogeneous catalysts.
Co-reporter:Zhi-Jian Yang, Ye-Fei Li, Qing-Bin Wu, Nan Ren, Ya-Hong Zhang, Zhi-Pan Liu, Yi Tang
Journal of Catalysis (13 June 2011) Volume 280(Issue 2) pp:247-254
Publication Date(Web):13 June 2011
DOI:10.1016/j.jcat.2011.03.026
Layered niobic acids (HxK1−xNb3O8, x = 0–1) are reported as new solid acid catalysts for the selective hydration of ethylene oxide (EO). They are prepared by simply calcinating Nb2O5–K2CO3 mixture followed by an ion-exchange process in HNO3 solution of different concentrations. The highest selectivity for monoethylene glycol (MEG) is achieved over 95% with EO conversion of >99% at x of 0.7 under H2O/EO ratio of 8. Combined with the results of first-principles density functional theory calculations and Hammett indicator method, it is revealed that the suitable acid strength is more crucial for MEG selectivity than acid amount. Furthermore, a self-exfoliation of layered HNb3O8 is also found during EO hydration, which proves to be another important factor for its good catalytic performance by exposing the abundant acid sites among the Nb3O8- nanosheets. The thermal stability investigation of HNb3O8 also indicates a careful selection of characterization and application way for this layered niobic acid.Graphical abstractLayered niobic acids are reported as efficient catalysts for the selective hydration of ethylene oxide. The adjustable acidity and in situ self-exfoliation effect are crucial for the good catalytic performance.Download high-res image (80KB)Download full-size imageHighlights► Layered HxK1−xNb3O8 as efficient catalyst for EO hydration. ► Suitable acid strength is crucial for high MEG selectivity. ► The self-exfoliation process is critical for good catalytic performance. ► Theoretical calculation is a valid method to characterize acid strength.
Co-reporter:Nan Ren, You-Hao Yang, Jiang Shen, Ya-Hong Zhang, Hua-Long Xu, Zi Gao, Yi Tang
Journal of Catalysis (1 October 2007) Volume 251(Issue 1) pp:182-188
Publication Date(Web):1 October 2007
DOI:10.1016/j.jcat.2007.07.009
Hollow zeolitically microcapsulized (HZMC) catalysts with encapsulated noble metal nanoparticles, such as Pt and Ag, have been successfully fabricated through a hydrothermal transformation process. A series of catalytic oxidation reactions of alcohols were performed both on HZMC catalysts and on commercial catalysts, such as Pt/SiO2 and Pt/Al2O3. The HZMC catalysts exhibit good reactant selectivity due to the existence of a zeolitic shell. More interestingly, the HZMC catalysts retained most of their reactivity even in the presence of a significant amount of poison contaminants (>5 vol%), whereas the reactivity on commercial catalysts was quickly quenched under the same conditions. Furthermore, the HZMC catalysts could be recycled for at least 6 runs without losing their activity, whereas the commercial catalysts deactivated rapidly with the recycling. The unique reactant-selectivity, poison-resistance, and reusability of the HZMC catalysts demonstrate that the strategy of zeolitic encapsulation for noble metal catalysts is effective and applicable in practice.
Co-reporter:Zhijie Hu, Hongbin Zhang, Lei Wang, Hongxia Zhang, Yahong Zhang, Hualong Xu, Wei Shen and Yi Tang
Catalysis Science & Technology (2011-Present) 2014 - vol. 4(Issue 9) pp:NaN2895-2895
Publication Date(Web):2014/06/10
DOI:10.1039/C4CY00376D
A highly stable MTP (methanol to propylene) catalyst, boron-modified hierarchical nanocrystalline ZSM-5 zeolite, has been constructed by a facile salt-aided seed-induced route. The cooperative effect of its hierarchical structure and modified acidity gives rise to a significantly stable activity (725 h) even at a high WHSV (weight hourly space velocity) of 4.0 h−1.
Co-reporter:Chao Sun, Yisu Yang, Junming Du, Feng Qin, Zhipan Liu, Wei Shen, Hualong Xu and Yi Tang
Chemical Communications 2012 - vol. 48(Issue 46) pp:NaN5789-5789
Publication Date(Web):2012/04/17
DOI:10.1039/C2CC30607G
A novel route for anti-deactivation of methanol-to-propylene catalyst has been established through supporting nano-gold on ZSM-5, which efficiently reinforces the catalytic stability due to the effect of gold nanoparticles on the stabilization of dehydrogenation intermediates within the coking process.
Co-reporter:Chao Sun, Junming Du, Jian Liu, Yisu Yang, Nan Ren, Wei Shen, Hualong Xu and Yi Tang
Chemical Communications 2010 - vol. 46(Issue 15) pp:NaN2673-2673
Publication Date(Web):2010/02/23
DOI:10.1039/B925850G
A novel route is proposed for the preparation of mesopore containing zeolite ZSM-5 via in situ hydrothermal treatment of a solution containing alkali-dissolved SBA-15 containing carbonized surfactant P123 in the mesopores; it exhibited prominent stability enhancement for methanol to propylene reaction.
Co-reporter:Yuanyuan Hu, Yahong Zhang and Yi Tang
Chemical Communications 2010 - vol. 46(Issue 22) pp:NaN3877-3877
Publication Date(Web):2010/05/05
DOI:10.1039/C002551H
Zeolite nanoparticles with various organosilanized surfaces have been synthesized in situ by a one-step approach which provides not only a functionalized surface for diverse host–guest interactions but also an attractive path for preparation of monodispersed template-free zeolite nanoparticles.
Co-reporter:Jing Shi, Lifeng Chen, Nan Ren, Yahong Zhang and Yi Tang
Chemical Communications 2012 - vol. 48(Issue 68) pp:NaN8585-8585
Publication Date(Web):2012/07/02
DOI:10.1039/C2CC33701K
A zeolitic platinum-encapsulated microcapsule was successfully employed in the one-pot tandem synthesis of hydrazone directly from cyclohexanol with high conversion, selectivity and reusability due to the promising protection of the zeolitic shell around the catalyst.
Co-reporter:Huanlei Lin, Zhangping Shi, Sina He, Xiang Yu, Sinong Wang, Qingsheng Gao and Yi Tang
Chemical Science (2010-Present) 2016 - vol. 7(Issue 5) pp:NaN3405-3405
Publication Date(Web):2016/02/12
DOI:10.1039/C6SC00077K
Exploring efficient noble-metal free electrocatalysts for the hydrogen evolution reaction (HER) is one of the most promising pathways for facing the energy crisis. Herein, MoC–Mo2C heteronanowires composed of well-defined nanoparticles were accomplished via controlled carbonization, showing excellent HER activity, fast kinetic metrics and outstanding stability in both acid and basic electrolytes. In particular, the optimal one consisting of 31.4 wt% MoC displayed a low overpotential (η10 = 126 and 120 mV for reaching a current density of −10 mA cm−2), a small Tafel slope (43 and 42 mV dec−1) and a low onset overpotential (38 and 33 mV) in 0.5 M H2SO4 and 1.0 M KOH, respectively. Such prominent performance, outperforming most of the current noble-metal free electrocatalysts, was ascribed to the carbide surface with an optimized electron density, and the consequently facilitated HER kinetics. This work elucidates a feasible way toward efficient electrocatalysts via heteronanostructure engineering, shedding some light on the exploration and optimization of catalysts in energy chemistry.
Co-reporter:Jing Shi, Yangdong Wang, Weimin Yang, Yi Tang and Zaiku Xie
Chemical Society Reviews 2015 - vol. 44(Issue 24) pp:NaN8903-8903
Publication Date(Web):2015/11/16
DOI:10.1039/C5CS00626K
The kaleidoscopic applications of zeolite catalysts (zeo-catalysts) in petrochemical processes has been considered as one of the major accomplishments in recent decades. About twenty types of zeolite have been industrially applied so far, and their versatile porous architectures have contributed their most essential features to affect the catalytic efficiency. This review depicts the evolution of pore models in zeolite catalysts accompanied by the increase in industrial and environmental demands. The indispensable roles of modulating pore models are outlined for zeo-catalysts for the enhancement of their catalytic performances in various industrial processes. The zeolites and related industrial processes discussed range from the uni-modal micropore system of zeolite Y (12-ring micropore, 12-R) in fluid catalytic cracking (FCC), zeolite ZSM-5 (10-R) in xylene isomerization and SAPO-34 (8-R) in olefin production to the multi-modal micropore system of MCM-22 (10-R and 12-R pocket) in aromatic alkylation and the hierarchical pores in FCC and catalytic cracking of C4 olefins. The rational construction of pore models, especially hierarchical features, is highlighted with a careful classification from an industrial perspective accompanied by a detailed analysis of the theoretical mechanisms.
Co-reporter:Zhangping Shi, Yangxia Wang, Huanlei Lin, Hongbin Zhang, Meikun Shen, Songhai Xie, Yahong Zhang, Qingsheng Gao and Yi Tang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 16) pp:NaN6013-6013
Publication Date(Web):2016/03/17
DOI:10.1039/C6TA01900E
The hydrogen evolution reaction using noble-metal free electrocatalysts has captured increasing attention due to its importance in renewable hydrogen production. Herein, a highly active and stable electrocatalyst of MoC encapsulated by graphitized carbon shells (nanoMoC@GS) has been developed via an in situ carburization of a Mo-based metal–organic framework (Mo-MOF) with the atomic periodic structure. The ultrafine MoC nanoparticles (∼3 nm) confined by 1–3 layered graphite shells significantly favor the efficient HER in both acidic and basic media. In particular, a low overpotential (η10 = 124 and 77 mV at a current density of −10 mA cm−2), a small Tafel slope (43 and 50 mV dec−1) and a high exchange current density (j0 = 0.015 and 0.212 mA cm−2) are achieved on nanoMoC@GS in 0.5 M H2SO4 and 1.0 M KOH, respectively. Such remarkable activity, outperforming most current noble-metal-free electrocatalysts, stems from the cooperative/synergistic effects of ultrafine MoC nanostructure, ultrathin and conductive graphitized carbon shells, and enriched porosity. This work demonstrates a feasible way to design high-performance electrocatalysts via converting “atomic contact” hybrid structures (e.g., MOFs), illustrating a new perspective for developing nanocatalysts in the energy chemistry field.
Co-reporter:Xiaowei Cheng, Jianjiang Mao, Xinchun Lv, Tao Hua, Xiaopeng Cheng, Yingcai Long and Yi Tang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 5) pp:NaN1251-1251
Publication Date(Web):2013/11/22
DOI:10.1039/C3TA14235C
Nanosized zeolite beta with a tuneable crystal morphology and size, rich intercrystalline mesoporosity and high catalytic activity for low-density polyethylene cracking, was fast transformed from a low-seeded, low-templated dry gel by a seeding-steam-assisted conversion method with a small quantity of water; the crystallization of zeolite beta is well induced within 28 h at a TEAOH/SiO2 of 0.1 with the aid of 1% seeds.
Co-reporter:Gaoxiang Liu, Sinong Wang, Yuting Nie, Xuhui Sun, Yahong Zhang and Yi Tang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 35) pp:NaN10129-10129
Publication Date(Web):2013/06/10
DOI:10.1039/C3TA11479A
A simple one-step hydrothermal route is developed to synthesize one-dimensional (1D) hexagonal tungsten bronze (HTB) nanostructures. The key to this route is utilizing the electrostatic attraction between negatively charged tungstate and protonated ethylenediamine (EDA) to create a special local reductive environment in a non-reductive aqueous solution, which contributes to the in situ reduction of some of the hexavalent tungsten atoms during the 1D growth process and the mixed-valent nature of the final HTB structure. The as-prepared HTB nanomaterials are characterized to be highly crystalline and of uniform 1D morphology. Influences of synthetic conditions, such as the pH value, reaction time, temperature and amount of EDA, are systematically investigated. Meanwhile, this strategy is successfully introduced to prepare a series of metal-doped 1D HTB nanomaterials by simply changing the type of starting alkali tungstate. Experimental evidence reveals that the formation of the products follows an electrostatic-induced reductive nucleation–dissolution–recrystallization process, and the electrostatic interaction between the two oppositely charged species plays an indispensable role in the growth of mixed-valent HTB nanostructures. More importantly, these nanomaterials show efficient transformation of near-infrared light into local heat, indicating their potential applications as a new genre of functional materials in photothermal energy conversion as well as other relevant criteria.
Co-reporter:Qingsheng Gao, Lichun Yang, Xinchun Lu, Jianjiang Mao, Yahong Zhang, Yuping Wu and Yi Tang
Journal of Materials Chemistry A 2010 - vol. 20(Issue 14) pp:NaN2812-2812
Publication Date(Web):2010/02/12
DOI:10.1039/B921001F
This paper presents a novel strategy to synthesize MoO2/carbon nanowires based on organic–inorganic hybrid nanocomposites with nanometre periodic structures. The organic–inorganic hybrid precursors provide uniform reactions throughout the composites for achieving novel carbon-hybrid structures and nano-morphology via easy calcination. Through the systematic physical characterization including scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, etc., the one-dimensional and carbon-hybrid structure of MoO2/C nanowires was confirmed. This synthetic strategy is also proved universal for other novel MoO2/C nanostructures based on various organic-inorganic hybrid precursors. Furthermore, the MoO2/C hybrid nanowires show good rate capability even at the high current density of 1000 mA g−1 as anode material for lithium ion battery.
Co-reporter:Qingsheng Gao, Chenxi Zhang, Sinong Wang, Wei Shen, Yahong Zhang, Hualong Xu and Yi Tang
Chemical Communications 2010 - vol. 46(Issue 35) pp:NaN6496-6496
Publication Date(Web):2010/08/09
DOI:10.1039/C0CC01430C
An effective and safe route is proposed to prepare supported Mo2C-based catalysts from organic–inorganic hybrids, which exhibit high activity and stability for producing H2 from methanol catalytic decomposition.
Co-reporter:Qingsheng Gao, Sinong Wang, Haocheng Fang, Jingwei Weng, Yahong Zhang, Jianjiang Mao and Yi Tang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 11) pp:NaN4715-4715
Publication Date(Web):2012/01/26
DOI:10.1039/C2JM15443A
The diverse structures of molybdate anions significantly provide new opportunities to design various nanostructures of MoOx-based organic–inorganic hybrids with prominent catalytic, electrochemical and photo/electrochromic properties. In this paper, the one-dimensional (1D) growth originating from anisotropic molybdate anions is successfully introduced to prepare a series of hybrid nanowires of Mo3O10(C6H8N)2·2H2O (anilinium trimolybdate), Mo3O10(C2H10N2) (ethylenediamine trimolybdate) and Mo3O10(C5H6N)2·H2O (pyridium trimolybdate). Taking Mo3O10(C6H8N)2·2H2O for example, the 1D growth is proved to be associated with the chain-like structure of Mo3O102− anions by both experiments and quantum chemical calculations. Meanwhile, the synthesis parameters, e.g., reacting time, pH conditions and feeding ratio, show obvious influences on product morphologies based on different molybdate anions, further validating the growth mechanism. More importantly, the as-obtained MoOx/amine nanostructures remarkably exhibit tunable photochromic properties depending on their 1D structures and hybrid composites, which presents the potential to design well-tailored functional optical nanodevices.
Co-reporter:Chenxi Zhang, Ping Chen, Jian Liu, Yahong Zhang, Wei Shen, Hualong Xu and Yi Tang
Chemical Communications 2008(Issue 28) pp:NaN3292-3292
Publication Date(Web):2008/06/16
DOI:10.1039/B807354F
A novel catalyst of silver microparticles embedded in a silicon nanowire array support (Ag@SiNW) was prepared by an in situ electroless metal deposition method; it exhibited high selectivity and stability for gas-phase oxidation of high alcohol to its corresponding aldehyde.
Co-reporter:Weilin Song, Bin Zhang, Lifeng Chen, Jing Shi, Xiaowei Cheng, Lianghua Wu, Weimin Yang, Jian Zhou, Yahong Zhang, Yuewu Tao and Yi Tang
Catalysis Science & Technology (2011-Present) 2016 - vol. 6(Issue 10) pp:NaN3567-3567
Publication Date(Web):2015/12/11
DOI:10.1039/C5CY01144B
A core–shell structured catalyst is considered effective for regulating product distribution in a complex reaction network. By systematically analyzing the behaviors of an Fe–Mn–Cu/SiO2@silicalite-1 core–shell catalyst in Fischer–Tropsch synthesis, a unique temperature-dependent role of the silicalite-1 shell is demonstrated on the distribution of products via modulation of the intra- and inter-pellet secondary reactions, which successfully fulfills synchronous increments of CO conversion, light olefin/light paraffin ratio (C2–4=/C2–40) and C2–4= selectivity, opposite to the behavior of a naked industrial Fe–Mn–Cu/SiO2 catalyst. This effect could be attributed to the different diffusion limitation of the silicalite-1 shell on various reactants/products in different temperature ranges. Such a discovery not only rationally explains the excellent performance of the core–shell catalyst on C2–4= production but also provides a new clue for the design of catalysts in complex reaction networks.
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