Jian-guo Wang

Enhanced Selectivity of Phenol Hydrogenation in Low-Pressure CO2 over Supported Pd Catalysts

Co-reporter:Tianzhu Liu, Hu Zhou, Bingbing Han, Yongbing Gu, Suiqin Li, Jian Zheng, Xing Zhong, Gui-Lin Zhuang, and Jian-guo Wang

ACS Sustainable Chemistry & Engineering December 4, 2017 Volume 5(Issue 12) pp:11628-11628

Publication Date(Web):October 24, 2017

DOI:10.1021/acssuschemeng.7b02974

Selective hydrogenation of phenol to cyclohexanone is an important process in both chemical industry and renewable feedstock processing. However, direct hydrogenation of phenol to cyclohexanone under mild conditions over catalysts with high reactivity, selectivity, and facile preparation is still a challenge. In the present study, we report that 99% conversion and 99% selectivity can be achieved over as-prepared Pd/γ-Al2O3 catalyst under the medium of low-pressure CO2 (0.05–0.2 MPa) and H2O at 373 K. According to experiment results, ab initio calculations and in situ high-pressure FTIR measurements indicated enhanced selectivity of cyclohexanone in low-pressure CO2; this result originated from the molecular interaction between cyclohexanone and CO2 and can prevent the further hydrogenation of cyclohexanone. Notably, enhancement of selectivity to cyclohexanone in low-pressure CO2 was also achieved using commercial Pd/γ-Al2O3 and Pd/C catalysts.Keywords: Cyclohexanone; Low-pressure CO2; Pd; Phenol hydrogenation;

Switchable CO2 electroreduction via engineering active phases of Pd nanoparticles

Co-reporter:Dunfeng Gao;Hu Zhou;Fan Cai;Dongniu Wang;Yongfeng Hu;Bei Jiang

Nano Research 2017 Volume 10( Issue 6) pp:2181-2191

Publication Date(Web):04 April 2017

DOI:10.1007/s12274-017-1514-6

Active-phase engineering is regularly utilized to tune the selectivity of metal nanoparticles (NPs) in heterogeneous catalysis. However, the lack of understanding of the active phase in electrocatalysis has hampered the development of efficient catalysts for CO2 electroreduction. Herein, we report the systematic engineering of active phases of Pd NPs, which are exploited to select reaction pathways for CO2 electroreduction. In situ X-ray absorption spectroscopy, in situ attenuated total reflection-infrared spectroscopy, and density functional theory calculations suggest that the formation of a hydrogen-adsorbed Pd surface on a mixture of the α- and β-phases of a palladium-hydride core (α+β PdHx@PdHx) above −0.2 V (vs. a reversible hydrogen electrode) facilitates formate production via the HCOO* intermediate, whereas the formation of a metallic Pd surface on the β-phase Pd hydride core (β PdHx@Pd) below −0.5 V promotes CO production via the COOH* intermediate. The main product, which is either formate or CO, can be selectively produced with high Faradaic efficiencies (>90%) and mass activities in the potential window of 0.05 to −0.9 V with scalable application demonstration.

Tuning the confinement space of N-carbon shell-coated ruthenium nanoparticles: highly efficient electrocatalysts for hydrogen evolution reaction

Co-reporter:Xianlang Chen;Jian Zheng;Xing Zhong;Yihan Jin;Guilin Zhuang;Xiaonian Li;Shengwei Deng

Catalysis Science & Technology (2011-Present) 2017 vol. 7(Issue 21) pp:4964-4970

Publication Date(Web):2017/10/30

DOI:10.1039/C7CY01539A

Development of efficient and durable catalysts for the hydrogen evolution reaction (HER) in an alkaline system is vital for the transformation of renewable energy into hydrogen fuel. In this study, we report the difference in the activity of semi- and fully-encapsulated Ru catalysts based on the effect of confined space. The fully-encapsulated Ru catalyst with porous nitrogen-doped carbon (5.0% F-Ru@PNC-800) displayed outstanding HER performance, a low overpotential of only 28 mV at 10 mA cm−2, and excellent stability. The fully-encapsulated Ru catalyst performs better than the semi-encapsulated Ru catalyst (5.0% S-Ru@PNC-800). Density functional theory calculation revealed that the different space sizes of carbon layers affect the charge transfer of the Ru nanoparticles and the carbon surface, leading to different activities. This work demonstrates that the control of confined space is an important strategy for designing highly efficient catalysts for energy conversion.

Selective phenol hydrogenation to cyclohexanone over alkali–metal-promoted Pd/TiO2 in aqueous media

Co-reporter:Hu Zhou;Bingbing Han;Tianzhu Liu;Xing Zhong;Guilin Zhuang;Jianguo Wang

Green Chemistry (1999-Present) 2017 vol. 19(Issue 15) pp:3585-3594

Publication Date(Web):2017/07/31

DOI:10.1039/C7GC01318C

Selective phenol hydrogenation to cyclohexanone is an important process in both the chemical industry and renewable feedstock processing. However, the direct hydrogenation of phenol to cyclohexanone at mild conditions remains challenging. Here, we report an easily manufactured catalyst, alkali–metal-promoted Pd/TiO2, achieves 99% phenol conversion and 99% cyclohexanone selectivity at mild conditions of 80 °C and an extremely low H2 pressure of 0.06 MPa in water. By contrast, only about 18–36% phenol conversion is achieved using Pd/TiO2 that without addition of alkali metal at the same conditions. The kinetic studies and TOF values indicate that K or Na metals indeed promote the phenol conversion without changing cyclohexanone selectivity. Further studies suggest that the change of electronic structures over Pd NPs that induced by alkali metal is the main reason for enhanced phenol conversion. This result, combined with DFT calculations, suggest that phenol hydrogenation occurs both along the direct hydrogenation pathway and the dissociation and hydrogenation pathway over Pd/TiO2, and that the main pathway over alkali–metal-promoted Pd/TiO2 catalysts is the dissociation and hydrogenation pathway.

Hierarchical Porous NC@CuCo Nitride Nanosheet Networks: Highly Efficient Bifunctional Electrocatalyst for Overall Water Splitting and Selective Electrooxidation of Benzyl Alcohol

Co-reporter:Jian Zheng;Xianlang Chen;Xing Zhong;Suiqin Li;Tianzhu Liu;Guilin Zhuang;Xiaonian Li;Shengwei Deng;Donghai Mei

Advanced Functional Materials 2017 Volume 27(Issue 46) pp:

Publication Date(Web):2017/12/01

DOI:10.1002/adfm.201704169

AbstractHighly active and stable bifunctional electrocatalysts for overall water splitting are important for clean and renewable energy technologies. The development of energy-saving electrocatalysts for hydrogen evolution reaction (HER) by replacing the sluggish oxygen evolution reaction (OER) with a thermodynamically favorable electrochemical oxidation (ECO) reaction has attracted increasing attention. In this study, a self-supported, hierarchical, porous, nitrogen-doped carbon (NC)@CuCo2Nx/carbon fiber (CF) is fabricated and used as an efficient bifunctional electrocatalyst for both HER and OER in alkaline solutions with excellent activity and stability. Moreover, a two-electrode electrolyzer is assembled using the NC@CuCo2Nx/CF as an electrocatalyst at both cathode and anode electrodes for H2 production and selective ECO of benzyl alcohol with high conversion and selectivity. The excellent electrocatalytic activity is proposed to be mainly due to the hierarchical architecture beneficial for exposing more catalytic active sites, enhancing mass transport. Density functional theoretical calculations reveal that the adsorption energies of key species can be modulated due to the synergistic effect between CoN and CuN. This work provides a reference for the development of high-performance bifunctional electrocatalysts for simultaneous production of H2 and high-value-added fine chemicals.

Mo Doping Induced More Active Sites in Urchin-Like W18O49 Nanostructure with Remarkably Enhanced Performance for Hydrogen Evolution Reaction

Co-reporter:Xing Zhong;Youyi Sun;Xianlang Chen;Guilin Zhuang;Xiaonian Li

Advanced Functional Materials 2016 Volume 26( Issue 32) pp:5778-5786

Publication Date(Web):

DOI:10.1002/adfm.201601732

Exploring highly efficient and inexpensive hydrogen evolution reaction (HER) electrocatalysts for various electrochemical energy conversion technologies is actively encouraged. Herein, a 3D urchin-like Mo-W₁₈O₄₉ nanostructure as an efficient HER catalyst is reported for the first time. The obtained Mo-W₁₈O₄₉ catalyst exhibits excellent electrocatalytic activity toward HER with small onset potential and Tafel slope. The prepared Mo-W₁₈O₄₉ electrode shows excellent durability after a long period. Density functional theory calculations reveal that the remarkably enhanced performance of Mo-W₁₈O₄₉ can be due to the ability of Mo dopant to increase the number of active sites, leading to optimal hydrogen adsorption on the active sites because of the electronic and geometric modulation. In addition, the urchin-like 3D morphology with a high surface area and abundant 1D nanowires promotes electron transfer, thereby ensuring fast interfacial charge transfer to improve electrocatalytic reactions. All these experimental and theoretical results clearly reveal that Mo-W₁₈O₄₉ intrinsically improves HER activity and thus has potential applications in water splitting.

Integrating cobalt phosphide and cobalt nitride-embedded nitrogen-rich nanocarbons: high-performance bifunctional electrocatalysts for oxygen reduction and evolution

Co-reporter:Xing Zhong, Yu Jiang, Xianlang Chen, Lei Wang, Guilin Zhuang, Xiaonian Li and Jian-guo Wang

Journal of Materials Chemistry A 2016 vol. 4(Issue 27) pp:10575-10584

Publication Date(Web):06 Jun 2016

DOI:10.1039/C6TA03820D

The demand for cost-effective bifunctional oxygen electrocatalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) for application in rechargeable metal–air batteries and fuel cells operated in alkaline solutions has increased over the decades. We report for the first time an easy procedure for a unique nitrogen-rich sandwich-architectured catalyst (CoNP@NC/NG) as a highly efficient bifunctional electrocatalyst for ORR and OER. Physical characterizations confirmed the coexistence of Co2P and CoxN crystal phases in the nanostructure. The as-prepared CoNP@NC/NG exhibited potent bifunctional electrochemical performance with superior positive onset potential, large kinetic current density, and outstanding stability toward both ORR and OER, thereby showing excellent activities compared with Pt/C and state-of-the-art nonprecious catalysts. The excellent performance could have originated from the robust conjugation between the Co2P and CoxN crystal structures leading to a synergistic effect of the two interfaces, and the carbon shell also increased the number of nitrogen active sites. Moreover, the integrated structure of CoNP@NC/NG provided high electrical conductivity and facilitated electron transfer. Furthermore, the rechargeable zinc–air battery testing of CoNP@NC/NG-700 revealed good performance and long-term stability. The current work provided a new pathway to design bifunctional catalysts with multiple crystal phases for energy conversion and storage.

Twin-like ternary PtCoFe alloy in nitrogen-doped graphene nanopores as a highly effective electrocatalyst for oxygen reduction

Co-reporter:Xing Zhong, Wenlei Xu, Lei Wang, Yingying Qin, Guilin Zhuang, Xiaonian Li and Jian-guo Wang

Catalysis Science & Technology 2016 vol. 6(Issue 15) pp:5942-5948

Publication Date(Web):20 Apr 2016

DOI:10.1039/C6CY00545D

Considerable advances have been achieved in the synthesis of Pt-based alloys for oxygen reduction reaction (ORR). However, early transition metals are vulnerable to dissolution, and the attained durability performance of ORR remains unsatisfactory. Here, a novel twin-like ternary PtCoFe alloy encapsulated in nitrogen-doped graphene nanopores (PtCoFe/NPG) was fabricated using platinum phthalocyanine (PtPc), iron phthalocyanine (FePc), and cobalt phthalocyanine (CoPc) as precursors. These metal Pc provided abundant nitrogen sources and facilitated the carbon supports doped with nitrogen during calcination. Most PtFeCo alloy nanoparticles are uniformly confined in the graphene nanopores. This composite markedly decreases Pt usage; the mass activity of PtCoFe/NPG 700 is 7.6 times higher than that of the commercial 20% Pt/C electrocatalyst, and the electrochemical durability of PtCoFe/NPG exhibits slow decay with a high current retention of 94.6%. The improved ORR catalytic performance of PtCoFe/NPG could be attributed to the synergy and strong electronic interaction between the twin-like PtCoFe alloy and the graphene nanopores. In addition, the large surface area and the formation of particular N–M bonds positively affected its ORR activity. This study opens up a new avenue for developing a variety of metal/graphene nanopore hybrids for potential use in energy devices and other technological devices.

Graphene Oxide Catalyzed CH Bond Activation: The Importance of Oxygen Functional Groups for Biaryl Construction

Co-reporter:Dr. Yongjun Gao;Pei Tang;Hu Zhou;Dr. Wei Zhang;Hanjun Yang;Dr. Ning Yan;Dr. Gang Hu;Dr. Donghai Mei;Dr. Jianguo Wang;Dr. Ding Ma

Angewandte Chemie International Edition 2016 Volume 55( Issue 9) pp:3124-3128

Publication Date(Web):

DOI:10.1002/anie.201510081

Abstract

A heterogeneous, inexpensive, and environmentally friendly graphene oxide catalytic system for the C−H bond arylation of benzene enables the formation of biaryl compounds in the presence of aryl iodides. The oxygen functional groups in these graphene oxide sheets and the addition of KOtBu are essential for the observed catalytic activity. Reactions with various model compounds and DFT calculations confirmed that these negatively charged oxygen atoms promote the overall transformation by stabilizing and activating K⁺ ions, which in turns facilitates the activation of the C−I bond. However, the graphene π system also greatly facilitates the overall reaction as the aromatic coupling partners are easily adsorbed.

Back Cover: Graphene Oxide Catalyzed CH Bond Activation: The Importance of Oxygen Functional Groups for Biaryl Construction (Angew. Chem. Int. Ed. 9/2016)

Co-reporter:Dr. Yongjun Gao;Pei Tang;Hu Zhou;Dr. Wei Zhang;Hanjun Yang;Dr. Ning Yan;Dr. Gang Hu;Dr. Donghai Mei;Dr. Jianguo Wang;Dr. Ding Ma

Angewandte Chemie International Edition 2016 Volume 55( Issue 9) pp:

Publication Date(Web):

DOI:10.1002/anie.201600740

Graphene Oxide Catalyzed CH Bond Activation: The Importance of Oxygen Functional Groups for Biaryl Construction

Co-reporter:Dr. Yongjun Gao;Pei Tang;Hu Zhou;Dr. Wei Zhang;Hanjun Yang;Dr. Ning Yan;Dr. Gang Hu;Dr. Donghai Mei;Dr. Jianguo Wang;Dr. Ding Ma

Angewandte Chemie 2016 Volume 128( Issue 9) pp:3176-3180

Publication Date(Web):

DOI:10.1002/ange.201510081

Abstract

A heterogeneous, inexpensive, and environmentally friendly graphene oxide catalytic system for the C−H bond arylation of benzene enables the formation of biaryl compounds in the presence of aryl iodides. The oxygen functional groups in these graphene oxide sheets and the addition of KOtBu are essential for the observed catalytic activity. Reactions with various model compounds and DFT calculations confirmed that these negatively charged oxygen atoms promote the overall transformation by stabilizing and activating K⁺ ions, which in turns facilitates the activation of the C−I bond. However, the graphene π system also greatly facilitates the overall reaction as the aromatic coupling partners are easily adsorbed.

Rcktitelbild: Graphene Oxide Catalyzed CH Bond Activation: The Importance of Oxygen Functional Groups for Biaryl Construction (Angew. Chem. 9/2016)

Co-reporter:Dr. Yongjun Gao;Pei Tang;Hu Zhou;Dr. Wei Zhang;Hanjun Yang;Dr. Ning Yan;Dr. Gang Hu;Dr. Donghai Mei;Dr. Jianguo Wang;Dr. Ding Ma

Angewandte Chemie 2016 Volume 128( Issue 9) pp:

Publication Date(Web):

DOI:10.1002/ange.201600740

First-Principles Thermodynamics Study of Spinel MgAl2O4 Surface Stability

Co-reporter:Qiuxia Cai, Jian-guo Wang, Yong Wang, and Donghai Mei

The Journal of Physical Chemistry C 2016 Volume 120(Issue 34) pp:19087-19096

Publication Date(Web):August 4, 2016

DOI:10.1021/acs.jpcc.6b02998

Size-Dependent Electrocatalytic Reduction of CO2 over Pd Nanoparticles

Co-reporter:Dunfeng Gao; Hu Zhou; Jing Wang; Shu Miao; Fan Yang; Guoxiong Wang; Jianguo Wang;Xinhe Bao

Journal of the American Chemical Society 2015 Volume 137(Issue 13) pp:4288-4291

Publication Date(Web):March 6, 2015

DOI:10.1021/jacs.5b00046

Size effect has been regularly utilized to tune the catalytic activity and selectivity of metal nanoparticles (NPs). Yet, there is a lack of understanding of the size effect in the electrocatalytic reduction of CO2, an important reaction that couples with intermittent renewable energy storage and carbon cycle utilization. We report here a prominent size-dependent activity/selectivity in the electrocatalytic reduction of CO2 over differently sized Pd NPs, ranging from 2.4 to 10.3 nm. The Faradaic efficiency for CO production varies from 5.8% at −0.89 V (vs reversible hydrogen electrode) over 10.3 nm NPs to 91.2% over 3.7 nm NPs, along with an 18.4-fold increase in current density. Based on the Gibbs free energy diagrams from density functional theory calculations, the adsorption of CO2 and the formation of key reaction intermediate COOH* are much easier on edge and corner sites than on terrace sites of Pd NPs. In contrast, the formation of H* for competitive hydrogen evolution reaction is similar on all three sites. A volcano-like curve of the turnover frequency for CO production within the size range suggests that CO2 adsorption, COOH* formation, and CO* removal during CO2 reduction can be tuned by varying the size of Pd NPs due to the changing ratio of corner, edge, and terrace sites.

Synergistic effect of S,N-co-doped mesoporous carbon materials with high performance for oxygen-reduction reaction and Li-ion batteries

Co-reporter:Gui-lin Zhuang, Jia-qi Bai, Xin-yong Tao, Jian-min Luo, Xin-de Wang, Yi-fen Gao, Xing Zhong, Xiao-nian Li and Jian-guo Wang

Journal of Materials Chemistry A 2015 vol. 3(Issue 40) pp:20244-20253

Publication Date(Web):25 Aug 2015

DOI:10.1039/C5TA05252A

S,N-co-doped porous carbon (SNPC) materials are good candidates for the cathodic oxygen-reduction reaction (ORR) and lithium-ion batteries (LIBs). However, SNPC gives low yield and is expensive. Herein, we report a new and efficient method for synthesizing a S,N-co-doped mesoporous carbon material through the carbonization of S,N-containing precursors in molten ZnCl2, where ZnCl2 served as the ionic solvent and Lewis acid catalyst. The resultant SNPC-800 showed a mesoporous structure with a specific surface area of 1235 m2 g−1 and a mesopore-size range of 10–45 nm, which were considerably larger than those obtained through the carbonization of ionic liquids and fabrication of graphene oxides. Furthermore, ORR measurements indicated good catalytic activity, comparable to the commercial Pt/C catalyst. Also the SNPC-800 material exhibited excellent catalytic stability, and high methanol tolerance compared to the commercial Pt/C catalyst. Density functional theory calculation results revealed that the catalytic properties originated from the synergistic effect of the S/N dopant and that the main catalytic reaction path followed an associative mechanism. LIB tests further showed high reversible capacity, as well as excellent cycling stability and rate performance.

Effect of graphene with nanopores on metal clusters

Co-reporter:Hu Zhou, Xianlang Chen, Lei Wang, Xing Zhong, Guilin Zhuang, Xiaonian Li, Donghai Mei and Jianguo Wang

Physical Chemistry Chemical Physics 2015 vol. 17(Issue 37) pp:24420-24426

Publication Date(Web):19 Aug 2015

DOI:10.1039/C5CP04368A

Porous graphene, which is a novel type of defective graphene, shows excellent potential as a support material for metal clusters. In this work, the stability and electronic structures of metal clusters (Pd, Ir, and Rh) supported on pristine graphene and graphene with different sizes of nanopores were investigated using first-principles density functional theory (DFT) calculations. Then, CO adsorption and oxidation on the Pd–graphene system were chosen to evaluate its catalytic performance. Graphene with nanopores can strongly stabilize the metal clusters and cause a substantial downshift of the d-band center of the metal clusters, thus decreasing CO adsorption. All binding energies, d-band centers, and adsorption energies show a linear change with the size of the nanopore: a bigger size of the nanopore corresponds to stronger bonding of metal clusters with graphene, lower downshift of the d-band center, and weaker CO adsorption. By using a suitable size nanopore, Pd clusters supported on graphene will have similar CO and O2 adsorption abilities, thus leading to superior CO tolerance. The DFT calculated reaction energy barriers show that graphene with nanopores is a superior catalyst for CO oxidation reaction. These properties can play an important role in instructing graphene-supported metal catalyst preparation to prevent the diffusion or agglomeration of metal clusters and enhance the catalytic performance.

Role of pretreatment with acid and base on the distribution of the products obtained via lignocellulosic biomass pyrolysis

Co-reporter:Xinde Wang, Shuai Leng, Jiaqi Bai, Hu Zhou, Xing Zhong, Guilin Zhuang and Jianguo Wang

RSC Advances 2015 vol. 5(Issue 32) pp:24984-24989

Publication Date(Web):27 Feb 2015

DOI:10.1039/C4RA15426F

The pretreatment of biomass could change the distribution of liquid products in pyrolysis. In this study, by controlling acid and base content in solutions, the pyrolysis of corncob pretreated by acid and basic solutions in boiling water were conducted. The results showed that different acid and base content in the pretreatment solution induced different liquid product distribution: the yield of furfural reached as high as 77% when the mass ratio of acid and corncob was 0.1:1, levoglucosenone (8.7%) was produced when H2SO4:corncob = 0.01:1, the high value-added chemicals like 4-vinyl guaiacol (6.3%), 2,3-dihydrobenzofuran (6.7%) and 1,2-cyclopentanedione (6.7%) could be obtained when H2SO4:corncob = 0.001:1, high yield of methanol (11.3%), benzene (22%), and 1-hydroxy-2-butanone (7.5%) were produced when NaOH:corncob = 0.08:1. Besides, the chemical varieties were different. For example, levoglucosenone could only be obtained when the ratio of acid and corncob was about 0.01:1, while 4-vinyl guaiacol and 2,3-dihydrobenzofuran could not be produced. More than that, pretreatment could also change the yields of gas and liquid during pyrolysis, but the yields of solid or bio-char remained constant. Meanwhile, the pretreatment by this method could lower the temperature of corncob pyrolysis compared with pretreatment by boiling water only.

Preparation and catalytic properties of Pd nanoparticles supported on micro-crystal DUT-67 MOFs

Co-reporter:Gui-lin Zhuang, Jia-qi Bai, Li Tan, Hong-liang Huang, Yi-fen Gao, Xing Zhong, Chong-li Zhong and Jian-guo Wang

RSC Advances 2015 vol. 5(Issue 41) pp:32714-32719

Publication Date(Web):25 Mar 2015

DOI:10.1039/C5RA03286E

Zr-based MOFs usually feature exceptionally high thermal and chemical stability, which suggests that composites of noble metals and Zr-based MOFs could have wide industrial applications. In this work, we report the synthesis and characterization of Pd nanoparticles (of three different loadings: 0.3%, 0.5% and 1.0%) supported on micro-crystal DUT-67 MOFs. Via SEM, TEM and XPS characterization methods, it was found that the Pd nanoparticles were well dispersed on the interface of the MOF micro-crystals, with a diameter of 3.5 nm, and both the dangling organic groups and the cavities of the MOFs play important roles. Furthermore, PXRD, IR, TGA and N2 adsorption measurements confirmed that the composites are very robust. Studies on the catalytic properties indicated that they have good catalytic performance with a conversion of 99% and selectivity of 89% in the Suzuki coupling reaction. By a series of explorations, we found the best catalytic conditions are an ethanol–water mixed solvent as the medium, K2CO3 as the base and a temperature of 70 °C. Moreover, good catalytic properties were also shown for the hydrogenation of nitrobenzene, where the optimum temperature was 60 °C, and a conversion of 99% and selectivity of 99% were achieved.

In Situ Fabrication of PtCo Alloy Embedded in Nitrogen-Doped Graphene Nanopores as Synergistic Catalyst for Oxygen Reduction Reaction

Co-reporter:Xing Zhong;Lei Wang;Hu Zhou;Yingying Qin;Wenlei Xu;Yu Jiang;Youyi Sun;Zheqi Shi;Guilin Zhuang;Xiaonian Li;Donghai Mei

Advanced Materials Interfaces 2015 Volume 2( Issue 17) pp:

Publication Date(Web):

DOI:10.1002/admi.201500365

Synergistic Effect of Nitrogen in Cobalt Nitride and Nitrogen-Doped Hollow Carbon Spheres for the Oxygen Reduction Reaction

Co-reporter:Xing Zhong;Lin Liu;Yu Jiang;Xinde Wang;Lei Wang;Guilin Zhuang;Xiaonian Li; Donghai Mei; Jian-guo Wang; Dang Sheng Su

ChemCatChem 2015 Volume 7( Issue 12) pp:1826-1832

Publication Date(Web):

DOI:10.1002/cctc.201500195

Abstract

The need for inexpensive and high-activity oxygen-reduction-reaction (ORR) electrocatalysts has attracted considerable research interest over the past years. Herein, we report a novel hybrid that contains cobalt nitride/nitrogen-rich hollow carbon spheres (Co_xN/NHCS) as a high-performance catalyst for ORR. The Co_xN nanoparticles were uniformly dispersed and confined in the hollow NHCS shell. The performance of the resulting Co_xN/NHCS hybrid was comparable with that of a commercial Pt/C at the same catalyst loading toward ORR, but the mass activity of the former was 5.7 times better than that of the latter. The nitrogen in both Co_xN and NHCS, especially Co_xN, could weaken the adsorption of reaction intermediates (O and OOH), which follows the favorable reaction pathway on Co_xN/NHCS according to the DFT-calculated Gibbs free-energy diagrams. Our results demonstrated a new strategy for the design and development of inexpensive, nonprecious-metal electrocatalysts for next-generation fuels.

Inside Cover: Synergistic Effect of Nitrogen in Cobalt Nitride and Nitrogen-Doped Hollow Carbon Spheres for the Oxygen Reduction Reaction (ChemCatChem 12/2015)

Co-reporter:Xing Zhong;Lin Liu;Yu Jiang;Xinde Wang;Lei Wang;Guilin Zhuang;Xiaonian Li; Donghai Mei; Jian-guo Wang; Dang Sheng Su

ChemCatChem 2015 Volume 7( Issue 12) pp:

Publication Date(Web):

DOI:10.1002/cctc.201500558

Catalytic Epoxidation Reaction over N-Containing sp2 Carbon Catalysts

Co-reporter:Wenjing Li, Yongjun Gao, Wulin Chen, Pei Tang, Weizhen Li, Zujin Shi, DangSheng Su, Jianguo Wang, and Ding Ma

ACS Catalysis 2014 Volume 4(Issue 5) pp:1261

Publication Date(Web):March 19, 2014

DOI:10.1021/cs500062s

Nitrogen-doped graphene treated with ammonia under different temperatures was used as the catalysts for the epoxidation of trans-stilbene and styrene at 373 K. NG-800 (N-doped graphene treated at 800 °C for 8 h) performed the best and gave the highest recyclable catalytic activity for the epoxidation of trans-stilbene, with 95.8% conversion and 94.4% selectivity to trans-stilbene epoxide. The catalytic center has been identified with the reaction mechanism elucidated by DFT calculation.Keywords: carbon catalyst; DFT calculation; epoxidation; nitrogen-doped graphene; trans-stilbene

Pyridyne cycloaddition of graphene: “external” active sites for oxygen reduction reaction

Co-reporter:Xing Zhong, Huiyou Yu, Guilin Zhuang, Qiang Li, Xinde Wang, Yuanshuai Zhu, Lin Liu, Xiaonian Li, Mingdong Dong and Jian-guo Wang

Journal of Materials Chemistry A 2014 vol. 2(Issue 4) pp:897-901

Publication Date(Web):29 Oct 2013

DOI:10.1039/C3TA13449K

“External” nitrogen doped graphene sheets via pyridyne cycloaddition were fabricated, which can serve as feasible Pt alternatives for oxygen reduction reaction electrocatalysts. Notably, the excellent ORR performance of PyNGs can be attributed to the possible adsorption and catalytic site of the ortho-carbon of “external” nitrogen.

A radar-like iron based nanohybrid as an efficient and stable electrocatalyst for oxygen reduction

Co-reporter:Xing Zhong, Lin Liu, Xinde Wang, Huiyou Yu, Guilin Zhuang, Donghai Mei, Xiaonian Li and Jian-guo Wang

Journal of Materials Chemistry A 2014 vol. 2(Issue 19) pp:6703-6707

Publication Date(Web):05 Mar 2014

DOI:10.1039/C4TA00647J

A new type of hybrid material consisting of iron phthalocyanine (FePc) coordinated with pyridyne cycloaddition of graphene sheets (PyNGs) as a high-performance electrocatalyst for ORR was fabricated. The Fe–PyNG hybrid has a similar overpotential but has a higher current density and superior stability compared to Pt/C in alkaline solutions for ORR.

Pt@Au Nanorods Uniformly Decorated on Pyridyne Cycloaddition Graphene as a Highly Effective Electrocatalyst for Oxygen Reduction

Co-reporter:Xing Zhong, Huiyou Yu, Xinde Wang, Lin Liu, Yu Jiang, Lei Wang, Guilin Zhuang, Youqun Chu, Xiaonian Li, and Jian-guo Wang

ACS Applied Materials & Interfaces 2014 Volume 6(Issue 16) pp:13448

Publication Date(Web):August 7, 2014

DOI:10.1021/am5020452

Preparing metal-supported graphene nanocomposites is both interesting and challenging because of their well-defined morphologies and have potential application for oxygen reduction reaction (ORR). Here, we present an easy approach to synthesizing a novel hybrid material composed of Pt@Au nanorods (NRs) uniformly dispersed on the pyridyne cycloaddition of graphene (Pt@Au-PyNG), and the material serves as a high-performance catalyst for ORR. This hybrid electrocatalyst significantly decreases the use of Pt by using Pt dispersed on Au NRs and shows a markedly high activity toward ORR. The resulting Pt@Au-PyNG hybrid displayed comparable electrocatalytic activity and better stability than commercial Pt/C in alkaline solutions toward ORR. The hybrid effectively blocks CO formation to increase catalyst resistance to CO poisoning, thereby decreasing the amount of Pt needed. Free-energy diagrams for ORR on Pt@Au (111) through dissociative and associative mechanisms show that OH or O hydrogenation is the rate-limiting step based on DFT calculations.Keywords: electrocatalysts; gold; graphene; oxygen reduction; platinum; pyridyne

Synthesis, properties, and magnetism–structure relationship of lanthanide-based metal–organic frameworks with (ethylenedithio)acetic acid

Co-reporter:Gui-lin Zhuang, Li Tan, Wu-lin Chen, Jia-qi Bai, Xing Zhong and Jian-guo Wang

CrystEngComm 2014 vol. 16(Issue 30) pp:6963-6970

Publication Date(Web):09 May 2014

DOI:10.1039/C4CE00573B

A series of new lanthanide-based metal–organic frameworks were prepared by the reaction of H2EDA ligand and Ln(NO3)3 (H2EDA = (ethylenedithio)acetic acid, Ln = La (1, 5), Nd (2), Eu (3) and Gd (4)). 1–4 exhibit three-dimensional isomorphic structures, while 5 displays a different framework than 1–4. It was found that the structures of the lanthanide MOFs are easyly influenced by the reaction conditions and the metal ion radius. Moreover, the emission spectra revealed that 3 exhibits good luminescence properties. Magnetism measurements showed that 4 has ferromagnetic properties. Quantum Monte Carlo (QMC) simulations revealed that the coupling parameter between two Gd(III) ions is 0.03 cm−1, suggesting a weak ferromagnetic exchange. Furthermore, under the consideration of strong correlations between localized f electrons, first principle density functional theory (DFT) calculations with the GGA + U approach showed that the magnetic properties of 4 are originated from the 4f electrons of Gd(III) propagating by a super-exchange pathway on two −/+/− spin nets of the carboxylate groups.

Geometric and electronic properties of graphene modified by “external” N-containing groups

Co-reporter:Xinde Wang, Qiuxia Cai, Guilin Zhuang, Xing Zhong, Donghai Mei, Xiaonian Li and Jianguo Wang

Physical Chemistry Chemical Physics 2014 vol. 16(Issue 38) pp:20749-20754

Publication Date(Web):14 Aug 2014

DOI:10.1039/C4CP03069A

Using first-principles spin polarized density functional theory (DFT) calculations, we investigated structures and electronic properties of “external” nitrogen-containing group (pyridine derivatives) modified graphene via a single or a double bonding mode. Our results show that in the most stable structures, the bonding between pyridine derivatives and graphene involves the ortho-carbon of pyridine derivatives, as confirmed by the Bader charge analysis. The enhanced stability of pyridine derivatives on graphene by [2+2] cycloaddition, e.g., a double bonding mode (DBPyNG), is caused by the matches between frontier orbitals of pyridine derivatives and those of graphene, which leads to the formation of stronger chemical bonds. Interestingly, electronic structure density of states (DOS) analysis of SBPyNG reveals that the spin-up and spin-down parts are clearly split while it is not the case for the double bonding pyridine derivative modified graphene (DBPyNG).

Carbon Nanotubes and Activated Carbons Supported Catalysts for Phenol in Situ Hydrogenation: Hydrophobic/Hydrophilic Effect

Co-reporter:Yizhi Xiang, Lingniao Kong, Pengyang Xie, Tieyong Xu, Jianguo Wang, and Xiaonian Li

Industrial & Engineering Chemistry Research 2014 Volume 53(Issue 6) pp:2197-2203

Publication Date(Web):January 24, 2014

DOI:10.1021/ie4035253

Carbon nanotube (CNTs) and activated carbon (AC) supported Pd and Ni catalysts were prepared for the (in situ) hydrogenation of phenol to cyclohexanone and cyclohexanol. The hydrophobic/hydrophilic properties of the catalysts were tailored by pretreating the carbonaceous support with HNO3 at various conditions and characterized by X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption (TPD), and transmission electron microscopy (TEM). The catalytic results suggested that Pd and Ni supported on CNTs show significantly higher activity than that supported on ACs. Pretreating the CNTs with HNO3 increases the local hydrophilicity of the active phase (by introducing oxygenated groups), which result in an increase in the cyclohexanone selectivity and strongly decrease the phenol conversion. The first-principles density functional theory calculation suggested that the adsorption/desorption behaviors of phenol, methanol, H2O, and cyclohexanone on the catalysts might be influenced highly by the hydrophobic/hydrophilic properties. The hydrophilic catalysts show high selectivity in cyclohexanone by lower conversion in phenol or vice versa.

Influence of Surface Chemistry of Activated Carbon on the Activity of Gold/Activated Carbon Catalyst in Acetylene Hydrochlorination

Co-reporter:Jinhui Xu, Jia Zhao, Jiangtao Xu, Tongtong Zhang, Xiaonian Li, Xiaoxia Di, Jun Ni, Jianguo Wang, and Jie Cen

Industrial & Engineering Chemistry Research 2014 Volume 53(Issue 37) pp:14272-14281

Publication Date(Web):September 8, 2014

DOI:10.1021/ie502683r

The main goal of this work is to study the relationship between the surface chemistry of activated carbon (AC) and the performance of respective gold-supported catalysts in the acetylene hydrochlorination. For this purpose, a set of modified activated carbons with different levels of oxygenated groups on the surface, but with no major differences in their textural parameters, was prepared. A strong effect of the surface chemistry of activated carbon on the Au/AC catalytic activity was observed. Comparison of characterizations, catalytic results, and DFT calculations suggests that phenol, ether, and carbonyl groups on activated carbon surface are the key members governing the unique catalytic activity and stability of Au3+ catalysts. The comprehensive experimental and theoretical study of the surface chemistry of Au3+ supported on activated carbon support is believed to be of great benefit for the rational design of gold–carbon composite catalysts for acetylene hydrochlorination.

The promoting role of minor amount of water in solvent-free hydrogenation of halogenated nitrobenzenes

Co-reporter:Jing-Hui Lyu, Xiao-Bo He, Chun-Shan Lu, Lei Ma, Qun-Feng Zhang, Feng Feng, Xiao-Nian Li, Jian-Guo Wang

Chinese Chemical Letters 2014 Volume 25(Issue 2) pp:205-208

Publication Date(Web):February 2014

DOI:10.1016/j.cclet.2013.10.024

This study shows that minor amount of water plays a very important role in solvent-free hydrogenation of halogenated nitrobenzenes. For dried sponge Pd, the reaction cannot occur in the absence of water. For Pd/C catalyst, minor amount of water reduces the induction time, increases the reaction rate and reaction TOFs. Water might enhance the diffusion, adsorption and dissociation of H2 on Pd catalysts.Minor amount of water has a significant role in enhancing the solvent-free hydrogenation of halogenated nitrobenzenes.

Size-Dependent Halogenated Nitrobenzene Hydrogenation Selectivity of Pd Nanoparticles

Co-reporter:Jinghui Lyu, Jianguo Wang, Chunshan Lu, Lei Ma, Qunfeng Zhang, Xiaobo He, and Xiaonian Li

The Journal of Physical Chemistry C 2014 Volume 118(Issue 5) pp:2594-2601

Publication Date(Web):January 9, 2014

DOI:10.1021/jp411442f

The selective hydrogenation of halogenated nitrobenzene (HNB) has been a great important chemical reaction in the fine chemical productions. In this study, the effect of metal particle size on the selective hydrogenation of HNB over Pd/C catalysts has been extensively investigated through the combination of theoretical (density functional theory calculations, DFT) and experimental methods. DFT calculations showed that the reaction barriers for dechlorination strongly depend on the type of reaction sites (terrace or edge), while the hydrogenation reaction barriers are nearly the same on different sites, which indicates that Pd nanoparticle size significantly affects the catalyst selectivity. Moreover, Pd nanoparticles with different sizes (from 2.1 to 30 nm) supported on activated carbon were synthesized using the methods developed by our group. In a 500 mL reactor, the selectivity is over 99.90% when the Pd nanoparticles are bigger than 25 nm. Finally, the industrial applications of the proposed catalyst were evaluated in several pilot factories. This study provides useful information on controlling the selectivity of other similar reactions catalyzed by noble-metal nanocatalysts.

Atomic-scale structures and interactions between the guanine quartet and potassium

Co-reporter:Wei Xu, Qinggang Tan, Miao Yu, Qiang Sun, Huihui Kong, Erik Lægsgaard, Ivan Stensgaard, Jørgen Kjems, Jian-guo Wang, Chen Wang and Flemming Besenbacher

Chemical Communications 2013 vol. 49(Issue 65) pp:7210-7212

Publication Date(Web):20 Jun 2013

DOI:10.1039/C3CC43302A

The atomic-scale identification of the G4K1 structural motif is achieved using an interplay of STM imaging and DFT calculations. Its high stability is found to be caused by the delicate balance between hydrogen bonding and metal–ligand interaction, which is of utmost relevance to model interactions of the G-quadruplex with cations in vivo.

The effect of earth metal ion on the property of peptide-based metal–organic frameworks

Co-reporter:Wu-lin Chen, Wen-Xian Chen, Gui-lin Zhuang, Jun Zheng, Li Tan, Xing Zhong and Jian-guo Wang

CrystEngComm 2013 vol. 15(Issue 27) pp:5545-5551

Publication Date(Web):09 May 2013

DOI:10.1039/C3CE40587G

A series of alkaline earth metal-based bio-analogous metal–organic frameworks (1–4) based on a cyclic dipeptide (2,5-piperazinedione-1,4-diacetic acid, H2PODC) were prepared under the same synthetic conditions and the effect of earth metal ion on the (geometrical and electronic) property of these MOFs was investigated. Crystal analysis demonstrates that the metal ion radii play an important role in coordination number, coordination modes of the ligand and bond length. The binding mode between metal ion and peptide can be divided into two groups: (1) Mg2+ and Sr2+; (2) Ca2+ and Ba2+ ions, where the difference is whether the carbonyl group participates in coordination. The result may be relevant to the different biophysical phenomena of protein between alkaline earth metal ions. UV-vis spectra show two adsorption peaks for compounds 1–4, while fluorescence spectra display one emission peak. Via first-principles density functional theory (DFT) calculation, we found that two adsorption peaks should be attributed to the transition of valence band (VB) → two empty bands and VB → conduction band (CB), while one emission peak may result from the transition of CB → VB.

Tuning the catalytic property of TiO2 nanotube arrays for water splitting

Co-reporter:Xi Pan, Qin Xie, Wu-lin Chen, Gui-lin Zhuang, Xing Zhong, Jian-guo Wang

International Journal of Hydrogen Energy 2013 Volume 38(Issue 5) pp:2095-2105

Publication Date(Web):19 February 2013

DOI:10.1016/j.ijhydene.2012.11.115

Doping is an important approach to modulate the catalytic properties, for example, the change of the overpotential, of TiO2 semiconductor for water splitting. In this study, by systematically investigating the thermodynamic properties of one-electron water splitting, we found that the required overpotentials can be divided into two groups: one is a high overpotential (∼1.0 V) on pristine TNTAs, Pt/TNTAs and N-TNTAs; and the other is a low overpotential (∼0.6 V) on F-TNTAs, Pt/N-TNTAs and Pt/F-TNTAs. And two kinds of linear relations between the binding energies of O, HO and HOO intermediates are further identified, which are unambiguously ascribed to the bonding characteristics between the reaction intermediates and the two types of TNTAs with the high and low overpotential, respectively. Therefore, the current work will make a step towards understanding the mechanism of water splitting on various doped TNTAs and designing the superior TiO2-based photoanode materials with lower overpotentials.Graphical abstractHighlights► Doping reduces the overpotential for water splitting on TNTAs. ► Two groups of overpotentials are found: high (∼1.0 V)and low (∼0.6 V). ► Two kinds of adsorption energies linear relations are identified.

Role of Phenolic Groups in the Stabilization of Palladium Nanoparticles

Co-reporter:Tie-yong Xu, Qun-feng Zhang, Hua-feng Yang, Xiao-nian Li, and Jian-guo Wang

Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 29) pp:9783-9789

Publication Date(Web):June 27, 2013

DOI:10.1021/ie401454n

For carbon supported Pd catalysts, the surface properties of activated carbons (ACs) are closely related with the Pd particle size. In this study, phenolic groups were adjustably introduced on ACs by hydrothermally treating ACs under different temperatures (433–513 K). Pd/ACs catalysts were prepared by the wetness impregnation method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), CO chemisorption, and H2-temperature-programmed reduction (TPR). The results revealed that the size of Pd nanoparticles (NPs) was highly dependent upon the amount of phenolic groups. The density functional theory (DFT) study suggested that the enhanced binding between palladium clusters and surface functional groups (SFGs) modified carbon nanotubes (CNTs) in the sequence: CNTs–O > CNTs–OH > CNTs–COOH > CNTs. Both the experimental and theoretical results suggested that phenolic groups on the surface of ACs play a vital role in the stabilization of Pd NPs, which provides insight into how to treat/or choose carbon supports for the preparation of small noble metal particles.

Solvent-free catalytic dehydrative etherification of benzyl alcohol over graphene oxide

Co-reporter:Huiyou Yu, Xinde Wang, Yuanshuai Zhu, Guilin Zhuang, Xing Zhong, Jian-guo Wang

Chemical Physics Letters 2013 Volume 583() pp:146-150

Publication Date(Web):17 September 2013

DOI:10.1016/j.cplett.2013.08.011

•GO exhibited a high activity and selectivity for benzyl alcohol etherification.•The reaction conditions were relatively mild and solvent-free.•GO is a possible metal free catalyst for a variety of applications in carbocatalysis.Graphene oxide (GO), prepared from oxidation of graphite powders using a modified Hummers method, exhibits a promising catalytic activity and a high selectivity for the solvent-free catalytic dehydrative etherification of benzyl alcohol (BA). A maximum yield (85.4%) of dibenzyl ether (DE) was achieved at 150 °C for 24 h when the BA/GO ration was 20 ml/g under solvent-free condition. This discovery provided a new insight into the development of GO as a carbocatalysts for a variety of applications in carbocatalysis.

Distinctions between Supported Au and Pt Catalysts for CO Oxidation: Insights from DFT Study

Co-reporter:Qiuxia Cai ; Xinde Wang

The Journal of Physical Chemistry C 2013 Volume 117(Issue 41) pp:21331-21336

Publication Date(Web):September 26, 2013

DOI:10.1021/jp406557f

Distinctions between supported Au and Pt catalysts on TiO2(110) for CO oxidation have been investigated by means of density functional theory calculations. Our study shows that the following factors determine the obvious differences between two kinds of catalysts for CO oxidation: (1) The adsorption strength of Au11 is much weaker than that of Pt11 on TiO2(110), but both are strongly dependent on the surface properties of TiO2. The addition of Pt increases the interaction between the alloyed cluster and TiO2 support. (2) O2 can adsorb only on the interfacial site between Au and TiO2(110), whereas O2 can adsorb on both the interfacial and metal sites of supported Pt nanoparticles. (3) CO is directly activated by the adsorbed molecular oxygen on the interfacial site of Au11/TiO2(110)_OH. While on Pt11/TiO2(110)_OH, the main reaction pathway is the dissociated oxygen reacting with CO. Once a Pt ensemble is formed on Au clusters (such as Au8Pt3/TiO2(110)_OH), both of the reaction mechanisms work.

Nitrogen-Doped sp2-Hybridized Carbon as a Superior Catalyst for Selective Oxidation

Co-reporter:Yongjun Gao;Dr. Gang Hu;Dr. Jun Zhong;Dr. Zujin Shi;Yuanshuai Zhu;Dr. Dang Sheng Su;Dr. Jianguo Wang;Dr. Xinhe Bao;Dr. Ding Ma

Angewandte Chemie International Edition 2013 Volume 52( Issue 7) pp:2109-2113

Publication Date(Web):

DOI:10.1002/anie.201207918

The effect of CNTs on structures and catalytic properties of AuPd clusters for H2O2 synthesis

Co-reporter:Hua-feng Yang, Peng-yang Xie, Hui-you Yu, Xiao-nian Li and Jian-guo Wang

Physical Chemistry Chemical Physics 2012 vol. 14(Issue 48) pp:16654-16659

Publication Date(Web):10 Sep 2012

DOI:10.1039/C2CP42691A

The structures and catalytic properties of AuPd clusters supported on carbon nanotubes (CNTs) for H2O2 synthesis have been investigated by means of density functional theory calculations. Firstly, the structures of AuPd clusters are strongly influenced by CNTs, in which the bottom layers are mainly composed of Pd and the top layers are a mix of Au and Pd due to the stronger binding of Pd than Au on CNTs. Especially, it is found that O2 adsorption on the Pd/CNTs interfacial sites is much weaker than that on the only Pd sites, which is in contrast to transition metal oxide (for example TiO2, Al2O3, CeO2) supported metal clusters. Furthermore, Pd ensembles on the interfacial sites have far superior catalytic properties for H2O2 formation than those away from CNT supports due to the changes in electronic structures caused by the CNTs. Therefore, our study provides a physical insight into the enhanced role of carbon supports in H2O2 synthesis over supported AuPd catalysts.

Brønsted–Evans–Polanyi Relations for H2O2 Synthesis on Gold Surfaces

Co-reporter:Yao-guang Wang

Catalysis Letters 2012 Volume 142( Issue 5) pp:601-607

Publication Date(Web):2012 May

DOI:10.1007/s10562-011-0752-6

By means of density functional theory calculations, the reaction mechanisms of H2O2 synthesis on three low index and two stepped Au surfaces have been investigated in detail. This study shows the activation energies of five elementary reaction steps of H2O2 synthesis, which include two hydrogenation and three decomposition steps of key species, are a function of reaction energies, which observe the Brønsted–Evans–Polanyi rules on both the flat Au surfaces and the step edge sites of stepped Au surfaces. This study not only provides a simple method to estimate the reaction barriers of elementary steps of H2O2 synthesis by the reaction energies but also predicts the catalytic performances of Au nanoparticles applied in real catalysis.

Enhanced role of Al or Ga-doped graphene on the adsorption and dissociation of N2O under electric field

Co-reporter:Yong-an Lv, Gui-lin Zhuang, Jian-guo Wang, Ya-bo Jia and Qin Xie

Physical Chemistry Chemical Physics 2011 vol. 13(Issue 27) pp:12472-12477

Publication Date(Web):09 Jun 2011

DOI:10.1039/C1CP20694J

To find an effective strategy for the capture and decomposition of nitrous oxide (N2O) is very important in order to protect the ozone layer and control the effects of global warming. Based on first-principles calculations, such a strategy is proposed by the systemic study of N2O interaction with pristine and Al (or Ga)-doped graphene, and N2O dissociation on the surface of Al (or Ga)-doped graphene in an applied electric field. The calculated adsorption energy value shows the N2O molecule more firmly adsorbs on the surface of Al (or Ga)-doped graphene than that of pristine graphene, deriving from a stronger covalent bond between the N2O molecule and the Al (or Ga) atom. Furthermore, our study suggests that N2O molecules can be easily decomposed to N2 and O2 with the appropriate electric field, which reveals that Al-doped graphene may be a new candidate for control of N2O.

Selectivity difference between hydrogenation of acetophenone over CNTs and ACs supported Pd catalysts

Co-reporter:Yi-zhi Xiang, Yong-an Lv, Tie-yong Xu, Xiao-nian Li, Jian-guo Wang

Journal of Molecular Catalysis A: Chemical 2011 Volume 351() pp:70-75

Publication Date(Web):December 2011

DOI:10.1016/j.molcata.2011.09.018

Selectivity difference between hydrogenation of acetophenone over carbon nanotubes (CNTs) and commercial activated carbons (ACs) supported Pd catalysts has been investigated. The selectivity of α-phenylethanol over the Pd/CNTs catalyst is significantly higher than that over the Pd/ACs. The optimal yield of α-phenylethanol over the Pd/CNTs catalyst is 94.2% at 333 K under atmospheric H2 pressure for 255 min, but it is only 47.9% over the Pd/ACs catalyst. HRTEM characterization and density functional theory (DFT) study of the two catalysts suggested that the defects of the carbon support are the main anchoring sites for Pd nanoparticles. Additionally, mechanistic study of the acetophenone hydrogenation over the two catalysts suggested that the different adsorption modes of reaction intermediates (products) on the two kinds carbon supported Pd nanoparticles are responsible for the dramatic selectivity difference.Graphical abstractThe catalytic hydrogenation of acetophenone over the Pd/CNTs catalyst shows significantly higher (-phenylethanol selectivity than that over the Pd/ACs catalyst due to the different adsorption modes of the reaction intermediates on the two kinds of catalysts.Highlights► High selective acetophenone hydrogenation over Pd/CNTs was observed. ► Selectivity of α-phenylethanol is ∼95% on Pd/CNTs and ∼5% on Pd/ACs. ► Pd nanoparticles were mainly adsorbed on the defects of both the CNTs and ACs support. ► Different adsorption modes of the α-phenylethanol on Pd nanoparticle lead to the selectivity difference.

The point-defect of carbon nanotubes anchoring Au nanoparticles

Co-reporter:Yong-An Lv, Yan-Hong Cui, Xiao-Nian Li, Xiang-Zhi Song, Jian-Guo Wang, Mingdong Dong

Physica E: Low-dimensional Systems and Nanostructures 2010 Volume 42(Issue 5) pp:1746-1750

Publication Date(Web):March 2010

DOI:10.1016/j.physe.2010.01.040

The understanding of the interaction between Au and carbon nanotubes (CNTs) is very important since Au/CNTs composites have wide applications in many fields. In this study, we investigated the dispersion of Au nanoparticles on the CNTs by transmission electron microscopy and the bonding mechanism between Au clusters and CNTs by means of density functional theory calculations. Both experimental and theoretical studies show that point defects are the anchoring sites of Au nanoparticles. The mechanisms of enhanced bond between Au and CNTs via the point defects are explained by the analysis of density of states, charge transfer and frontier molecular orbitals.

A DFT Study of the Adhesion of Pd Clusters on ZnO SWNTs and Adsorption of Gas Molecules on Pd/ZnO SWNTs

Co-reporter:Yan Su, Qiang-qiang Meng and Jian-guo Wang

The Journal of Physical Chemistry C 2009 Volume 113(Issue 51) pp:21338-21341

Publication Date(Web):November 11, 2009

DOI:10.1021/jp907977q

We investigated the adhesion of Pd nanoclusters on ZnO SWNTs and adsorption of probe gas molecules (O2, H2, and CO) on the outside or inside wall of ZnO and Pd1/ZnO SWNTs by means of density functional theory calculations in this study. Our study shows that the binding of Pd clusters on ZnO is mainly via the Pd−O bond interaction. The Pd monomer has the same adhesion ability on both the outside and the inside wall of ZnO SWNTs. However, we found that the adsorption energy of O2 is larger on the inside wall of ZnO and Pd1/ZnO SWNTs than that on the outside one, which is caused by the confinement effect.

PtPd alloy embedded in nitrogen-rich graphene nanopores: High-performance bifunctional electrocatalysts for hydrogen evolution and oxygen reduction

Co-reporter:Xing Zhong, Yingying Qin, Xianlang Chen, Wenlei Xu, Guilin Zhuang, Xiaonian Li, Jianguo Wang

Carbon (April 2017) Volume 114() pp:

Publication Date(Web):April 2017

DOI:10.1016/j.carbon.2016.12.004

Searching for high-efficiency and low-cost bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) has been actively encouraged for their promising applications. We report a facile strategy to prepare PtPd alloy embedded in nitrogen-rich graphene nanopores (Pt2Pd/NPG) as highly efficient bifunctional electrocatalysts for HER and ORR. The as-prepared Pt2Pd/NPG exhibits prominent onset potential, excellent stability, good kinetic current density, and remarkable corrosion resistance to HER and ORR. Density functional theory (DFT) calculations reveal that the remarkably enhanced performance of Pt2Pd/NPG originated from the robust conjugation between the Pt2Pd alloy nanoparticles and nitrogen-rich graphene nanopores, thereby leading to the synergistic effect of both interfaces. The nanopores also modulate the electronic properties of Pt2Pd alloy nanoparticles, which improve the durability during HER and ORR. A novel approach for preparing high-performance bifunctional electrocatalysts with embedded metal alloy in nitrogen-rich carbon is presented. The process has potential applications in energy conversion and storage.Pt2Pd nanoparticles embedded in nitrogen-rich nanopores (Pt2Pd/NPG) was fabricated, serving as a high-performance bifunctional electrocatalysts for hydrogen evolution and oxygen reduction.

Preface

Co-reporter:Qingfeng Ge, Jian-guo Wang, Jun Li

Catalysis Today (16 May 2011) Volume 165(Issue 1) pp:

Publication Date(Web):16 May 2011

DOI:10.1016/j.cattod.2011.03.001

Water splitting on TiO2 nanotube arrays

Co-reporter:Qiang-qiang Meng, Jian-guo Wang, Qin Xie, Hua-qing Dong, Xiao-nian Li

Catalysis Today (16 May 2011) Volume 165(Issue 1) pp:145-149

Publication Date(Web):16 May 2011

DOI:10.1016/j.cattod.2010.11.086

TiO2 nanotube arrays can be synthesized by several experimental procedures. Here we construct the first theoretical model of the array. Based on the density functional theory calculations, the formation energy of the TiO2 nanotube array is nearly the same as that of rutile TiO2 (1 1 0) surface. Moreover the electronic properties of TiO2 nanotube arrays have been analyzed. The thermodynamic properties of H2O splitting on the TiO2 nanotube and nanotube arrays have been discussed using the density functional theory calculations and Gibbs free energy diagrams. The overpotential of H2O splitting is 0.51 and 1.0 eV on the outside and inside of nanotube and 1.13 eV on the inside TiO2 nanotube of an array.

Twin-like ternary PtCoFe alloy in nitrogen-doped graphene nanopores as a highly effective electrocatalyst for oxygen reduction

Co-reporter:Xing Zhong, Wenlei Xu, Lei Wang, Yingying Qin, Guilin Zhuang, Xiaonian Li and Jian-guo Wang

Catalysis Science & Technology (2011-Present) 2016 - vol. 6(Issue 15) pp:NaN5948-5948

Publication Date(Web):2016/04/20

DOI:10.1039/C6CY00545D

Considerable advances have been achieved in the synthesis of Pt-based alloys for oxygen reduction reaction (ORR). However, early transition metals are vulnerable to dissolution, and the attained durability performance of ORR remains unsatisfactory. Here, a novel twin-like ternary PtCoFe alloy encapsulated in nitrogen-doped graphene nanopores (PtCoFe/NPG) was fabricated using platinum phthalocyanine (PtPc), iron phthalocyanine (FePc), and cobalt phthalocyanine (CoPc) as precursors. These metal Pc provided abundant nitrogen sources and facilitated the carbon supports doped with nitrogen during calcination. Most PtFeCo alloy nanoparticles are uniformly confined in the graphene nanopores. This composite markedly decreases Pt usage; the mass activity of PtCoFe/NPG 700 is 7.6 times higher than that of the commercial 20% Pt/C electrocatalyst, and the electrochemical durability of PtCoFe/NPG exhibits slow decay with a high current retention of 94.6%. The improved ORR catalytic performance of PtCoFe/NPG could be attributed to the synergy and strong electronic interaction between the twin-like PtCoFe alloy and the graphene nanopores. In addition, the large surface area and the formation of particular N–M bonds positively affected its ORR activity. This study opens up a new avenue for developing a variety of metal/graphene nanopore hybrids for potential use in energy devices and other technological devices.

Synergistic effect of S,N-co-doped mesoporous carbon materials with high performance for oxygen-reduction reaction and Li-ion batteries

Co-reporter:Gui-lin Zhuang, Jia-qi Bai, Xin-yong Tao, Jian-min Luo, Xin-de Wang, Yi-fen Gao, Xing Zhong, Xiao-nian Li and Jian-guo Wang

Journal of Materials Chemistry A 2015 - vol. 3(Issue 40) pp:NaN20253-20253

Publication Date(Web):2015/08/25

DOI:10.1039/C5TA05252A

S,N-co-doped porous carbon (SNPC) materials are good candidates for the cathodic oxygen-reduction reaction (ORR) and lithium-ion batteries (LIBs). However, SNPC gives low yield and is expensive. Herein, we report a new and efficient method for synthesizing a S,N-co-doped mesoporous carbon material through the carbonization of S,N-containing precursors in molten ZnCl2, where ZnCl2 served as the ionic solvent and Lewis acid catalyst. The resultant SNPC-800 showed a mesoporous structure with a specific surface area of 1235 m2 g−1 and a mesopore-size range of 10–45 nm, which were considerably larger than those obtained through the carbonization of ionic liquids and fabrication of graphene oxides. Furthermore, ORR measurements indicated good catalytic activity, comparable to the commercial Pt/C catalyst. Also the SNPC-800 material exhibited excellent catalytic stability, and high methanol tolerance compared to the commercial Pt/C catalyst. Density functional theory calculation results revealed that the catalytic properties originated from the synergistic effect of the S/N dopant and that the main catalytic reaction path followed an associative mechanism. LIB tests further showed high reversible capacity, as well as excellent cycling stability and rate performance.

Enhanced role of Al or Ga-doped graphene on the adsorption and dissociation of N2O under electric field

Co-reporter:Yong-an Lv, Gui-lin Zhuang, Jian-guo Wang, Ya-bo Jia and Qin Xie

Physical Chemistry Chemical Physics 2011 - vol. 13(Issue 27) pp:NaN12477-12477

Publication Date(Web):2011/06/09

DOI:10.1039/C1CP20694J

To find an effective strategy for the capture and decomposition of nitrous oxide (N2O) is very important in order to protect the ozone layer and control the effects of global warming. Based on first-principles calculations, such a strategy is proposed by the systemic study of N2O interaction with pristine and Al (or Ga)-doped graphene, and N2O dissociation on the surface of Al (or Ga)-doped graphene in an applied electric field. The calculated adsorption energy value shows the N2O molecule more firmly adsorbs on the surface of Al (or Ga)-doped graphene than that of pristine graphene, deriving from a stronger covalent bond between the N2O molecule and the Al (or Ga) atom. Furthermore, our study suggests that N2O molecules can be easily decomposed to N2 and O2 with the appropriate electric field, which reveals that Al-doped graphene may be a new candidate for control of N2O.

The effect of CNTs on structures and catalytic properties of AuPd clusters for H2O2 synthesis

Co-reporter:Hua-feng Yang, Peng-yang Xie, Hui-you Yu, Xiao-nian Li and Jian-guo Wang

Physical Chemistry Chemical Physics 2012 - vol. 14(Issue 48) pp:NaN16659-16659

Publication Date(Web):2012/09/10

DOI:10.1039/C2CP42691A

The structures and catalytic properties of AuPd clusters supported on carbon nanotubes (CNTs) for H2O2 synthesis have been investigated by means of density functional theory calculations. Firstly, the structures of AuPd clusters are strongly influenced by CNTs, in which the bottom layers are mainly composed of Pd and the top layers are a mix of Au and Pd due to the stronger binding of Pd than Au on CNTs. Especially, it is found that O2 adsorption on the Pd/CNTs interfacial sites is much weaker than that on the only Pd sites, which is in contrast to transition metal oxide (for example TiO2, Al2O3, CeO2) supported metal clusters. Furthermore, Pd ensembles on the interfacial sites have far superior catalytic properties for H2O2 formation than those away from CNT supports due to the changes in electronic structures caused by the CNTs. Therefore, our study provides a physical insight into the enhanced role of carbon supports in H2O2 synthesis over supported AuPd catalysts.

Geometric and electronic properties of graphene modified by “external” N-containing groups

Co-reporter:Xinde Wang, Qiuxia Cai, Guilin Zhuang, Xing Zhong, Donghai Mei, Xiaonian Li and Jianguo Wang

Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 38) pp:NaN20754-20754

Publication Date(Web):2014/08/14

DOI:10.1039/C4CP03069A

Using first-principles spin polarized density functional theory (DFT) calculations, we investigated structures and electronic properties of “external” nitrogen-containing group (pyridine derivatives) modified graphene via a single or a double bonding mode. Our results show that in the most stable structures, the bonding between pyridine derivatives and graphene involves the ortho-carbon of pyridine derivatives, as confirmed by the Bader charge analysis. The enhanced stability of pyridine derivatives on graphene by [2+2] cycloaddition, e.g., a double bonding mode (DBPyNG), is caused by the matches between frontier orbitals of pyridine derivatives and those of graphene, which leads to the formation of stronger chemical bonds. Interestingly, electronic structure density of states (DOS) analysis of SBPyNG reveals that the spin-up and spin-down parts are clearly split while it is not the case for the double bonding pyridine derivative modified graphene (DBPyNG).

Effect of graphene with nanopores on metal clusters

Co-reporter:Hu Zhou, Xianlang Chen, Lei Wang, Xing Zhong, Guilin Zhuang, Xiaonian Li, Donghai Mei and Jianguo Wang

Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 37) pp:NaN24426-24426

Publication Date(Web):2015/08/19

DOI:10.1039/C5CP04368A

Porous graphene, which is a novel type of defective graphene, shows excellent potential as a support material for metal clusters. In this work, the stability and electronic structures of metal clusters (Pd, Ir, and Rh) supported on pristine graphene and graphene with different sizes of nanopores were investigated using first-principles density functional theory (DFT) calculations. Then, CO adsorption and oxidation on the Pd–graphene system were chosen to evaluate its catalytic performance. Graphene with nanopores can strongly stabilize the metal clusters and cause a substantial downshift of the d-band center of the metal clusters, thus decreasing CO adsorption. All binding energies, d-band centers, and adsorption energies show a linear change with the size of the nanopore: a bigger size of the nanopore corresponds to stronger bonding of metal clusters with graphene, lower downshift of the d-band center, and weaker CO adsorption. By using a suitable size nanopore, Pd clusters supported on graphene will have similar CO and O2 adsorption abilities, thus leading to superior CO tolerance. The DFT calculated reaction energy barriers show that graphene with nanopores is a superior catalyst for CO oxidation reaction. These properties can play an important role in instructing graphene-supported metal catalyst preparation to prevent the diffusion or agglomeration of metal clusters and enhance the catalytic performance.

A radar-like iron based nanohybrid as an efficient and stable electrocatalyst for oxygen reduction

Co-reporter:Xing Zhong, Lin Liu, Xinde Wang, Huiyou Yu, Guilin Zhuang, Donghai Mei, Xiaonian Li and Jian-guo Wang

Journal of Materials Chemistry A 2014 - vol. 2(Issue 19) pp:NaN6707-6707

Publication Date(Web):2014/03/05

DOI:10.1039/C4TA00647J

A new type of hybrid material consisting of iron phthalocyanine (FePc) coordinated with pyridyne cycloaddition of graphene sheets (PyNGs) as a high-performance electrocatalyst for ORR was fabricated. The Fe–PyNG hybrid has a similar overpotential but has a higher current density and superior stability compared to Pt/C in alkaline solutions for ORR.

Pyridyne cycloaddition of graphene: “external” active sites for oxygen reduction reaction

Co-reporter:Xing Zhong, Huiyou Yu, Guilin Zhuang, Qiang Li, Xinde Wang, Yuanshuai Zhu, Lin Liu, Xiaonian Li, Mingdong Dong and Jian-guo Wang

Journal of Materials Chemistry A 2014 - vol. 2(Issue 4) pp:NaN901-901

Publication Date(Web):2013/10/29

DOI:10.1039/C3TA13449K

“External” nitrogen doped graphene sheets via pyridyne cycloaddition were fabricated, which can serve as feasible Pt alternatives for oxygen reduction reaction electrocatalysts. Notably, the excellent ORR performance of PyNGs can be attributed to the possible adsorption and catalytic site of the ortho-carbon of “external” nitrogen.

Integrating cobalt phosphide and cobalt nitride-embedded nitrogen-rich nanocarbons: high-performance bifunctional electrocatalysts for oxygen reduction and evolution

Co-reporter:Xing Zhong, Yu Jiang, Xianlang Chen, Lei Wang, Guilin Zhuang, Xiaonian Li and Jian-guo Wang

Journal of Materials Chemistry A 2016 - vol. 4(Issue 27) pp:NaN10584-10584

Publication Date(Web):2016/06/06

DOI:10.1039/C6TA03820D

The demand for cost-effective bifunctional oxygen electrocatalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) for application in rechargeable metal–air batteries and fuel cells operated in alkaline solutions has increased over the decades. We report for the first time an easy procedure for a unique nitrogen-rich sandwich-architectured catalyst (CoNP@NC/NG) as a highly efficient bifunctional electrocatalyst for ORR and OER. Physical characterizations confirmed the coexistence of Co2P and CoxN crystal phases in the nanostructure. The as-prepared CoNP@NC/NG exhibited potent bifunctional electrochemical performance with superior positive onset potential, large kinetic current density, and outstanding stability toward both ORR and OER, thereby showing excellent activities compared with Pt/C and state-of-the-art nonprecious catalysts. The excellent performance could have originated from the robust conjugation between the Co2P and CoxN crystal structures leading to a synergistic effect of the two interfaces, and the carbon shell also increased the number of nitrogen active sites. Moreover, the integrated structure of CoNP@NC/NG provided high electrical conductivity and facilitated electron transfer. Furthermore, the rechargeable zinc–air battery testing of CoNP@NC/NG-700 revealed good performance and long-term stability. The current work provided a new pathway to design bifunctional catalysts with multiple crystal phases for energy conversion and storage.

Atomic-scale structures and interactions between the guanine quartet and potassium

Co-reporter:Wei Xu, Qinggang Tan, Miao Yu, Qiang Sun, Huihui Kong, Erik Lægsgaard, Ivan Stensgaard, Jørgen Kjems, Jian-guo Wang, Chen Wang and Flemming Besenbacher

Chemical Communications 2013 - vol. 49(Issue 65) pp:NaN7212-7212

Publication Date(Web):2013/06/20

DOI:10.1039/C3CC43302A

The atomic-scale identification of the G4K1 structural motif is achieved using an interplay of STM imaging and DFT calculations. Its high stability is found to be caused by the delicate balance between hydrogen bonding and metal–ligand interaction, which is of utmost relevance to model interactions of the G-quadruplex with cations in vivo.

Experimental, DFT and quantum Monte Carlo studies of a series of peptide-based metal–organic frameworks: synthesis, structures and properties

Co-reporter:Gui-lin Zhuang, Li Tan, Wu-lin Chen, Jun Zheng, Hong-zhou Yao, Xing Zhong and Jian-guo Wang

Inorganic Chemistry Frontiers 2014 - vol. 1(Issue 7) pp:

Publication Date(Web):

DOI:10.1039/C4QI00043A