Co-reporter:Heng Wang, Yawei Li, Tianbin Zhu, Zhengyi Fu
Ceramics International 2017 Volume 43, Issue 13(Volume 43, Issue 13) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.ceramint.2017.04.178
The novel carbon sources (including nano-carbon black, carbon nanotubes and graphene oxide nanosheets, etc.) have been extensively researched in low carbon Al2O3-C refractory systems. In the present work, ultrafine microcrystalline graphite (UMCG) and nickel-loaded ultrafine microcrystalline graphite (NMCG) were added into low carbon Al2O3-C slide gate plate refractories to partially replace graphite flake (GF), respectively. The mechanical properties, phase compositions and microstructures were investigated by three-point bending test, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. Also, the reaction mechanisms of in-situ formed ceramic phases were discussed by thermodynamic analysis. The results indicate that the existence of UMCG powders can facilitate the in-situ formation of intertwined ceramic whiskers, leading to increased densification and mechanical properties of low carbon Al2O3-C slide gate plate. Moreover, multi-walled carbon nanotubes and ceramic phases intensively interlock with each other in the Al2O3-C refractories containing NMCG powders, which results in their better mechanical properties; the cold modulus of rupture are 36.03±0.12 MPa and 32.14±0.17 MPa for the specimens after coking at 1200 °C and 1350 °C, respectively. This work puts forward a practical application for the microcrystalline graphite as a candidate carbon source in Al2O3-C slide gate plate refractories.
Co-reporter:Mingyu Xiang, Jingjing Xie, Wei Ji, Hang Ping, ... Zhengyi Fu
Journal of the European Ceramic Society 2017 Volume 37, Issue 8(Volume 37, Issue 8) pp:
Publication Date(Web):1 July 2017
DOI:10.1016/j.jeurceramsoc.2017.03.002
Zirconium carbide (ZrC0.84O0.13) nanopowders were consolidated using plasma activated sintering with 0–8 wt% ZrH2 as the sintering additive to improve the sinterability. Compared with pure ZrC sintering, ZrH2 additive led to the higher sintering kinetics and lower sintering temperature. This improvement was attributed to the increased carbon-vacancy concentration in the non-stoichiometric ZrC in the presence of ZrH2 additive during the sintering process. Fully dense and fine-grained ZrC ceramics (1.3 ± 0.2 μm) were achieved at 1650 °C with 6 wt.% ZrH2. The final product exhibited the Vicker’s hardness of 21.2 ± 1.0 GPa and fracture toughness of 2.2 ± 0.3 MPa m1/2.
Co-reporter:Hang Ping, Hao Xie, Zhengyi Fu
Journal of Materiomics 2017 Volume 3, Issue 2(Volume 3, Issue 2) pp:
Publication Date(Web):1 June 2017
DOI:10.1016/j.jmat.2017.03.001
•New structures in confined space inspired by natural structure-forming processes have been systematically reviewed.•Artificial confinements direct the synthesis of materials with defined structures according to the geometry of confinements.•Biological confinements with specific spatial distribution can control the formation of periodic structure.•Designed confinements with desired modification can provide platforms for the synthesis of three-dimensional nanostructures.•Novel structures will be rationally fabricated in the future with the aid of deeper understanding of biological processes.In living organisms, confined space with specific chemical composition and elaborate spatial distribution regulates the formation of natural structures. Learning from the natural structure-forming process, novel synthesis approaches in deliberated confined systems have been proposed for obtaining designed structures. Artificial confined systems can effectively regulate the synthesis of materials with defined structures according to the geometry of confinements. Collagen fibrils provide biological confinements for the formation of hierarchical structure with periodic arrangement. Genetically engineered living organisms with designed confinements can direct the synthesis of three-dimensional nanostructures. More novel structures will be rationally fabricated in the future with the aid of deeper understanding of biological processes.Download high-res image (341KB)Download full-size image
Co-reporter:Guimin Zhang, Xiaodi Du, Yucheng Wang, Hao Wang, Weimin Wang, Zhengyi Fu
Materials Science in Semiconductor Processing 2017 Volume 64(Volume 64) pp:
Publication Date(Web):15 June 2017
DOI:10.1016/j.mssp.2017.03.010
Series of SnS2 nanostructures were synthesized by a facile refluxing process. Influencing factors on the microstructures and properties of SnS2 were investigated, including the reaction temperature, adding sequence of reagent and the solvent. The results indicated the as-prepared SnS2 products in lower temperature had larger surface areas and superior adsorption capability than that in higher temperature. SnS2 nanoflowers prepared at 120 °C in ethylene glycol exhibited remarkable adsorption capability for cationic dyes and heavy metal of Pb2+, Cd2+. Intriguingly, the products also showed prominent visible light photocatalystic activity for Methyl Orange (MO). The formation mechanisms of different SnS2 nanostructures were proposed; the release of S2- played a crucial role on controlling the morphology of SnS2. The simple shape-controlled method can be extended to the synthesis of other metal sulfides and the high adsorption property is favorable to it coupling with other semiconductors or noble metals to far improve photocatalytic activity.
Co-reporter:Hang Ping, Hao Xie, Yamin Wan, Zhixiao Zhang, Jing Zhang, Mingyu Xiang, Jingjing Xie, Hao Wang, Weimin Wang and Zhengyi Fu
Journal of Materials Chemistry A 2016 vol. 4(Issue 5) pp:880-886
Publication Date(Web):18 Dec 2015
DOI:10.1039/C5TB01990G
Confinement is common in biological systems and plays a critical role in the structure-forming process of biominerals. However, the knowledge of confinement effects on biomineralization is limited due to the lack of specific chemical structures and elaborate spatial distribution. In this article, we explore the confined mineralization of amorphous calcium carbonate (ACC) within collagen fibrils. Three issues of the confined mineralization of ACC within collagen fibrils were investigated, including the morphology and characteristics of the confined mineralization of ACC within collagen fibrils; the initiation and development of the confined mineralization of ACC within collagen fibrils; and the driving mechanism of ACC infiltration into collagen fibrils. Results show that the negatively charged ACC droplets were attracted to positively charged gap regions of collagen fibrils through electrostatic interactions, infiltrated into collagen fibrils, and then transformed into the crystalline phase. The observation of juxtaposed crystalline and amorphous phases on the surface of fibrils indicates that a secondary nucleation mechanism may be responsible for the co-orientation of calcite nanocrystals. Through modifying the wettability of amorphous calcium carbonate with magnesium ions, it is verified that the infiltration of ACC into collagen fibrils was driven by capillary forces. The present study not only provides evidence of the confinement effects in biomineralization but also facilitates the understanding of the in vivo bone formation process. It may also open up a new avenue in the bioprocess-inspired synthesis of advanced materials.
Co-reporter:Jing Zhang, Bin Yao, Hang Ping, Zhengyi Fu, Yu Li, Weimin Wang, Hao Wang, Yucheng Wang, Jinyong Zhang and Fan Zhang
RSC Advances 2016 vol. 6(Issue 1) pp:472-480
Publication Date(Web):01 Dec 2015
DOI:10.1039/C5RA18366A
A uniform, hierarchical porous vaterite calcium carbonate microsphere stacked from nanoparticles is synthesized in dimethylformamide–water (DMF–H2O) mixed solvent without template. We propose a solvent-reaction assisted synthesis of the product by a mesoscale growth pathway. The product shows large removal capacity towards Pb2+, Cd2+ and Zn2+, of 1960 mg g−1, 1040 mg g−1 and 587.3 mg g−1, respectively. It also exhibits efficient and selective adsorption of Congo red (272 mg g−1, 5 min for equilibrium), which is reported for the first time on calcium carbonate. The removal mechanism is demonstrated to be the precipitation transformation for the heavy metal ion sequestration, and adsorption mechanism for the removal of the organic dyes. The good performance of the product is ascribed to the large amount of active adsorption sites provided by the nanoscale building blocks and mesopores, and the short pathway provided by the sunken poles and the hierarchical structure with enhanced mass transfer and decreased blocking of channels.
Co-reporter:Wei Ji, Richard I. Todd, Weimin Wang, Hao Wang, Jinyong Zhang, Zhengyi Fu
Journal of the European Ceramic Society 2016 Volume 36(Issue 10) pp:2419-2426
Publication Date(Web):August 2016
DOI:10.1016/j.jeurceramsoc.2016.03.028
Fully-dense B4C-based ceramics were fabricated using Ti-Al intermetallics as sintering aid by Spark Plasma Sintering at a low temperature of 1700 °C whilst applying 32 MPa uniaxial pressure. The influence of the intermetallic additions on the phase composition, morphology and mechanical properties of the ceramics were investigated. The intermetallics flowed and react with B4C to form a three-phase composite containing B4C, TiB2 and Al4C3 during the transient liquid phase sintering process. The TiB2 and Al4C3 particles were located on the boundaries between B4C grains and effectively inhibited the growth of B4C, which improved the mechanical properties. Good bonding between B4C and the phases formed was confirmed by TEM analysis. The specimens with 5 wt.% Ti-Al provide an attractive combination of homogeneous morphology and excellent mechanical properties, including a Vickers hardness of 33.5 ± 0.4 GPa, a flexural strength of 506 ± 16 MPa and a fracture toughness of 5.5 ± 0.1 MPa m0.5.
Co-reporter:Dr. Jingjing Xie; Hao Xie; Bao-Lian Su; Yi-bing Cheng; Xiaodong Du;Dr. Hui Zeng;Dr. Menghu Wang; Weimin Wang; Hao Wang; Zhengyi Fu
Angewandte Chemie 2016 Volume 128( Issue 9) pp:3083-3087
Publication Date(Web):
DOI:10.1002/ange.201509906
Abstract
Structure-forming processes leading to biominerals are well worth learning in pursuit of new synthetic techniques. Strategies that attempt to mimic nature in vitro cannot replace an entire complex natural organism, requiring ingenuity beyond chemists′ hands. A “bioprocess-inspired synthesis” is demonstrated for fabrication of N-doped TiO2 materials at ambient temperature by direct implantation of precursor into living mussels. The amorphous precursor transforms into N-doped anatase TiO2 with a hierarchical nanostructure. Synthetic TiO2 exhibits high phase stability and enhanced visible-light photocatalytic activity as a result of modifications to its band gap during in vivo mineralization. Intracellular proteins were found to be involved in TiO2 mineralization. Our findings may inspire material production by new synthetic techniques, especially under environmentally benign conditions.
Co-reporter:Dr. Jingjing Xie; Hao Xie; Bao-Lian Su; Yi-bing Cheng; Xiaodong Du;Dr. Hui Zeng;Dr. Menghu Wang; Weimin Wang; Hao Wang; Zhengyi Fu
Angewandte Chemie International Edition 2016 Volume 55( Issue 9) pp:3031-3035
Publication Date(Web):
DOI:10.1002/anie.201509906
Abstract
Structure-forming processes leading to biominerals are well worth learning in pursuit of new synthetic techniques. Strategies that attempt to mimic nature in vitro cannot replace an entire complex natural organism, requiring ingenuity beyond chemists′ hands. A “bioprocess-inspired synthesis” is demonstrated for fabrication of N-doped TiO2 materials at ambient temperature by direct implantation of precursor into living mussels. The amorphous precursor transforms into N-doped anatase TiO2 with a hierarchical nanostructure. Synthetic TiO2 exhibits high phase stability and enhanced visible-light photocatalytic activity as a result of modifications to its band gap during in vivo mineralization. Intracellular proteins were found to be involved in TiO2 mineralization. Our findings may inspire material production by new synthetic techniques, especially under environmentally benign conditions.
Co-reporter:Hui Zeng, Jingjing Xie, Hao Xie, Bao-Lian Su, Menghu Wang, Hang Ping, Weimin Wang, Hao Wang and Zhengyi Fu
Journal of Materials Chemistry A 2015 vol. 3(Issue 38) pp:19588-19596
Publication Date(Web):24 Aug 2015
DOI:10.1039/C5TA04649A
Inspired by the structure-forming process of biominerals, scientists have been successful in synthesizing materials with elegant structures by using organic matrices as templates. However, there are still issues relating to the exquisiteness and complexity of natural organic matrices in living organisms which have kept their activities out of chemists' control, in particular the functional properties of such materials. Here we employ natural assorted proteins, which are derived from the extrapallial fluid in living mussels, to synthesize hierarchically porous nitrogen-doped TiO2 in a single process. The silk-like organic residues in the powders clearly show that the proteins act to segment the space for TiO2 nucleation. We also demonstrate phase control over the material, with the ability to synthesize pure anatase. The synthesized TiO2 materials show a significant improvement in visible-light photocatalytic activity for both the degradation of organic pollutants and hydrogen production. The degradation of RhB could be almost completed in just 20 min. The visible-light photocatalytic activities vary with the concentrations of EPF proteins, and the optimal concentration of protein was found to be 600 μg mL−1. The present work highlights its potential application as a natural organic matrix in producing advanced materials with optimized functional properties.
Co-reporter:X.-L. Wang, H. Xie, B.-L. Su, Y.-B. Cheng, J.-J. Xie, H. Ping, M.-H. Wang, J.-Y. Zhang, F. Zhang and Z.-Y. Fu
Journal of Materials Chemistry A 2015 vol. 3(Issue 29) pp:5951-5956
Publication Date(Web):09 Jun 2015
DOI:10.1039/C5TB00650C
Living organisms can produce elegant structures with unique functions and properties through biological processes. Various proteins are involved in these processes. Inspired by the structure formation of mollusc shells, a single multifunctional recombinant protein ChiCaSifi was designed on the basis of mineralization proteins for regulating CaCO3 mineralization in a simple and direct manner. ChiCaSifi contains functional domains of the chitin binding protein (Chi), the calcium binding protein (Ca), and the silk fibroin (Sifi). Therefore, ChiCaSifi can have multiple roles in directing CaCO3 mineralization. Overexpression and purification of ChiCaSifi were achieved. Activities of ChiCaSifi were examined for its binding to calcium and chitin. Influences of ChiCaSifi in regulating the phase formation of CaCO3 crystals on the chitin surface were proved. Structural changes of ChiCaSifi were evidenced and related to its functions on mineralization. These observations indicate that rationally designed proteins with functional domains of mineralization proteins can be effective tools in materials synthesis. The present study may not only provide an insight into the formation of natural biomaterials, but also open a new avenue in the design and synthesis of novel organic–inorganic composite materials.
Co-reporter:Hang Ping, Hao Xie, Bao-Lian Su, Yi-bing Cheng, Weimin Wang, Hao Wang, Yucheng Wang, Jinyong Zhang, Fan Zhang and Zhengyi Fu
Journal of Materials Chemistry A 2015 vol. 3(Issue 22) pp:4496-4502
Publication Date(Web):01 May 2015
DOI:10.1039/C5TB00386E
Taking lessons from the structure-forming process of biominerals in animals and plants, one can find tremendous inspirations and ideas for developing advanced synthesis techniques, which is called bio-process inspired synthesis. Bone, as a typical representative of biominerals, is constituted of mineralized collagen fibrils, which are formed under the functions of non-collagenous proteins (NCPs). Intrafibrillar mineralization is the consequence of a synergy among several NCPs. In the present study, we have designed a multi-functional protein, named (MBP)–BSP–HAP, based on bone sialoprotein (BSP) and hydroxyapatite binding protein (HAP), to mimic the intrafibrillar mineralization process in vitro. The three functional domains of (MBP)–BSP–HAP provide the artificial protein with multiple designated functions for intrafibrillar mineralization including binding calcium ions, binding collagen, and binding hydroxyapatite. Platelet-like hydroxyapatite crystals periodically arranged inside the collagen fibrils have been achieved under the function of (MBP)–BSP–HAP. The mechanism of intrafibrillar mineralization directed by the multi-functional protein was proposed. This work may not only shed light on bio-process inspired approaches for more economic and efficient biomimetic synthesis, but also be helpful in understanding the natural process of bone formation for bone regeneration and tissue repair.
Co-reporter:Jing Zhang, Yu Li, Hao Xie, Bao-Lian Su, Bin Yao, Yixia Yin, Shipu Li, Fang Chen, and Zhengyi Fu
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 29) pp:15686
Publication Date(Web):July 10, 2015
DOI:10.1021/acsami.5b04819
Developing drug delivery systems (DDSs) with high drug-loading capacity and sustainable releasing is critical for long-term chemotherapeutic efficacy, and it still remains challenging. Herein, vaterite CaCO3 nanoplate assemblies with exposed high-energy {001} facets have been synthesized via a novel, additive-free strategy. The product shows a high doxorubicin-loading capacity (65%); the best of all the CaCO3-based DDSs so far. Also, the product’s sustainable releasing performance and its inhibition of the initial burst release, together, endow it with long-term drug efficacy. The work may shed light on exposing directed high-energy facets for rationally designing of a drug delivery system with long-term efficacy.Keywords: additive-free synthesis; calcium carbonate; drug delivery; high-energy facet; nanostructure;
Co-reporter:Lin Ren, Zhengyi Fu, Yucheng Wang, Fan Zhang, Jinyong Zhang, Weimin Wang, Hao Wang
Journal of the European Ceramic Society 2015 Volume 35(Issue 6) pp:1915-1921
Publication Date(Web):June 2015
DOI:10.1016/j.jeurceramsoc.2014.12.025
Nanosized mullite with an average crystal size below 100 nm was synthesized by spark plasma sintering combined with a sol–gel process and the addition of glucose to the precursor materials. A suppression of grain growth was achieved by adding glucose. The influence of glucose was studied by evaluating samples with a glucose/Al3+ ratio of 0:1, 1:1, and 3:1, respectively. The sample prepared without glucose was the least homogeneous and showed a low relative density and irregular microstructure after sintering. In contrast, the sample prepared with a glucose/Al3+ ratio of 3:1 was the most homogeneous, leading nearly full densified mullite with nanosized grains at lower sintering temperature.
Co-reporter:Guimin Zhang, Zhengyi Fu, Yucheng Wang, Hao Wang and Zheng Xie
RSC Advances 2015 vol. 5(Issue 102) pp:83922-83930
Publication Date(Web):28 Sep 2015
DOI:10.1039/C5RA17679D
A CdS/Cd2SnO4 composite was successfully synthesized via a one step solvothermal route synergistically assisted by L-cysteine and diethanolamine. The composite is composed of CdS quantum dots stuffed in hierarchical Cd2SnO4 microspheres with a diameter of around 2 μm, which are assembled from nanosheets with a thickness of 20–50 nm. The band gap of the composite is 2.46 eV, which is higher than pure phase CdS and Cd2SnO4, due to the quantum size effect from CdS QDs. One possible formation mechanism of the composite is presented; the initial precipitation of Sn(OH)2 serves as a template, and the complexes of L-cysteine coordinated with metal ion provide structural direction for the hierarchical microspheres. The CdS/Cd2SnO4 composite showed superior adsorption ability and enhanced visible light photocatalytic activity in the degradation of RhB to CdS, Cd2SnO4, and Degussa P-25, due to its microstructure and the efficient charge separation at the interface of CdS and Cd2SnO4.
Co-reporter:Shuang-Hong Xue, Hao Xie, Hang Ping, Qi-Chang Li, Bao-Lian Su and Zheng-Yi Fu
RSC Advances 2015 vol. 5(Issue 88) pp:71844-71848
Publication Date(Web):10 Aug 2015
DOI:10.1039/C5RA13619A
Extreme conditions such as high temperature and/or pressure are usually required for the transformation of amorphous silica to crystalline polymorphs. In this article, we present our results that amorphous silica can be deposited on a bacterial surface and transformed to cristobalite at a relatively low temperature and ambient pressure. The phase transformation of amorphous silica to cristobalite under thermal treatment was investigated by a variety of methods including X-ray diffraction, electron microscopy, and Fourier transform infrared spectroscopy. Results show that amorphous silica on a bacterial cell surface exhibits a direct phase transformation to cristobalite structure at a relatively low temperature (800 °C). The surface charge of the bacterial cells does not affect the phase transformation. Three Gram-negative bacteria and three Gram-positive bacteria have been tested in the present study. All these bacteria have been found to facilitate the phase transition of amorphous silica into cristobalite. The observation of amorphous silica transformation on bacterial surfaces to cristobalite highlights the use of bacteria in the synthesis and structure control of silica minerals.
Co-reporter:Wei Ji, Weimin Wang, Hao Wang, Jinyong Zhang, Yucheng Wang, Fan Zhang, Zhengyi Fu
Intermetallics 2015 Volume 56() pp:24-27
Publication Date(Web):January 2015
DOI:10.1016/j.intermet.2014.08.008
An equiatomic CoCrFeNiMn high-entropy alloy was synthesized by mechanical alloying (MA) and spark plasma sintering (SPS). During MA, a solid solution with refined microstructure of 10 nm which consists of a FCC phase and a BCC phase was formed. After SPS consolidation, only one FCC phase can be detected in the HEA bulks. The as-sintered bulks exhibit high compressive strength of 1987 MPa. An interesting magnetic transition associated with the structure coarsening and phase transformation was observed during SPS process.
Co-reporter:B. Li;X. Zheng;Z. F. Fu
International Journal of Self-Propagating High-Temperature Synthesis 2015 Volume 24( Issue 1) pp:14-20
Publication Date(Web):2015 January
DOI:10.3103/S1061386215010069
Dense nanocrystalline yttria ceramics without grain growth were obtained within a short densification period by a method combining SHS reaction and quick pressing (SHS-QP). The reactive mixtures consisting of Ni and Al with TiC as a diluent were used as a heat source. An yttria compact was inserted inside the reactants and warmed up by reaction heat at a heating rate of above 1300°C/min. When the temperature reached its maximum, high mechanical pressure was applied to the sample for densification. Dense nanocrystalline yttria was produced when temperature T was 1350°C and pressure P, 120 MPa. The rapid densification process was accomplished in 1 min. Microstructural analysis showed almost no grain growth compared to initial powder. For comparison, the hot pressing (HP) process was also used to densify the same yttria powders. The results prove that the HP process causes grains coarsening even when the sintering temperature is 1250°C.
Co-reporter:Hui Zeng 曾辉;Jingjing Xie;Hang Ping
Journal of Wuhan University of Technology-Mater. Sci. Ed. 2015 Volume 30( Issue 1) pp:65-70
Publication Date(Web):2015 February
DOI:10.1007/s11595-015-1102-0
Highly oriented calcium carbonate lamellas are exquisite structure produced by biomineralization. Strategies mimicking nature have been developed to synthesize inorganic materials with excellent structures and optimal properties. In our strategy, egg white protein and zinc ion were employed in the solution to induce the crystallization of calcium carbonate, resulting in the macroscopic aragonite laminate with an average length of 1.5 mm, which was comprised of single-crystalline tablets. During the crystallization at initial stage, it was found that the particles displayed the characteristics of amorphous calcium carbonate, which was then transformed into the sophisticated structured aragonite through a multistage assembly process. The rebuilt nacre structure in vitro was achieved owing to the synergistic effects of egg white protein and zinc ion.
Co-reporter:Shahzad Ahmad Khan 傅正义
Journal of Wuhan University of Technology-Mater. Sci. Ed. 2015 Volume 30( Issue 6) pp:1163-1166
Publication Date(Web):2015 December
DOI:10.1007/s11595-015-1289-0
Here, a new idea was proposed for template-free synthesis of hierarchical m-ZrO2 nanorods and “their” possible formation mechanism based on a series of chemical reactions by simple hydrothermal method. The traditional preparation methods of hierarchical ZrO2 nanorods involved inexpensive equipment, complicated process, and high production cost. The as-synthesized products composed of many nanorods with 180-200 nm in diameter and 5-7 μm in length. The final product after annealing involved hierarchical monoclinic ZrO2 (m-ZrO2) nanorods, namely, the big nanorod was made up of many small nanorods with 40-50 nm in diameter and 500-600 nm in length. The experimental results were useful in understanding the chemical properties of ZrB2 and ZrO2 and the design of the derivatives for m-ZrO2 nanomaterials.
Co-reporter:Jingjing Xie, Zhengyi Fu, Yucheng Wang, Soo Wohn Lee, Koichi Niihara
Journal of the European Ceramic Society 2014 Volume 34(Issue 1) pp:13.e1-13.e7
Publication Date(Web):January 2014
DOI:10.1016/j.jeurceramsoc.2013.07.003
Zirconium carbide nanopowders were synthesized by a novel method combining the advantages of sol–gel method and rapid synthesis using pulse current heating. The core-shelled structure of ZrO2/C mixture was obtained during the sol–gel process, and further heat treatment in SPS led to the fast formation of ZrC. The particle size of ZrO2 played an important role in the synthesis of nanosized ZrC powders. In addition, the coalescence and grain growth of ZrC particles could be also limited due to the fast heating rate. As a result, the reactions were thoroughly completed at a relatively low temperature and ZrC nanopowders of 60–100 nm were obtained. The corresponding powders also had low oxygen content (∼0.64 wt%) and residual carbon content (∼0.27 wt%). Additive-free ZrC powders could be sintered to ∼99% relative density with an average grain size of 0.8 μm at low temperature of 1750 °C.
Co-reporter:Jianghao Liu, Zhengyi Fu, Weimin Wang, Jinyong Zhang, Hao Wang, Yucheng Wang, Soowohn Lee, Koichi Niihara
Journal of the European Ceramic Society 2014 Volume 34(Issue 12) pp:3095-3102
Publication Date(Web):October 2014
DOI:10.1016/j.jeurceramsoc.2014.04.004
The pressure-assisted densification method based on combustion reaction heating was applied to prepare dense nanocrystalline ceramics. The densification process of magnesia compact with a particle size of 50 nm was investigated, under the pressure range of 0–170 MPa, and the temperature range of 1620–1880 K with ultra-high heating rate (above 1600 K/min). The pressure was found to have an effect on enhancing densification while suppressing grain growth, and the higher sintering temperature lead to the larger grain size and lower density of the compact. Pure magnesia nanocrystalline ceramics with a relative density of 99.1% was obtained at 1620 K and 170 MPa, and the concurrent grain growth was almost completely restrained. Furthermore, the investigation on the pressure-dependent densification mechanisms including plastic flow, diffusion and power-law creep was also carried out. The result indicated the rate-controlling mechanism was the plastic flow accommodated by grain-boundary diffusion creep.
Co-reporter:Jianghao Liu, Zhengyi Fu, Weimin Wang, Jinyong Zhang, Hao Wang, Yucheng Wang, Soo Wohn Lee, Koichi Niihara
Journal of the European Ceramic Society 2014 Volume 34(Issue 10) pp:2475-2482
Publication Date(Web):September 2014
DOI:10.1016/j.jeurceramsoc.2014.02.015
Combustion reaction plus quick pressing was a developing technique that used the Joule heating effect of combustion reaction to sinter ceramics, and allows very high heating rate, short soaking duration and high pressure for densification of ceramics. By taking advantages of the particular conditions of this method, pure yttria ceramics with a relative density of 98.5% and an average grain size of 50 nm were obtained at 1620 K and 170 MPa. Moreover, the investigation on the grain growth of sintered yttria was carried out by analyzing the microstructure evolutions and responsible mechanisms. The combined effect of the ultra-high heating rate and the high pressure applied on compact at the peak temperature was effective in suppressing particle coarsening and enhancing densification. Besides, under the decreased sintering temperature and soaking duration, the retained nanostructure assisted to inhibit final-stage grain growth while without impeding the further densification of nanocrystalline ceramics.
Co-reporter:Shahzad Ahmad Khan, Zhengyi Fu, Sahibzada Shakir Rehman, Muhammad Asif, Weimin Wang, Hao Wang
Powder Technology 2014 Volume 256() pp:71-74
Publication Date(Web):April 2014
DOI:10.1016/j.powtec.2014.02.012
•A new idea is proposed for template-free synthesis of hierarchical m-ZrO2 nanorods.•A formation mechanism was proposed based on a series of chemical reactions.•It is useful for the design of ZrB2, ZrO2 and its derivatives for m-ZrO2.The template-free synthesis of hierarchical m-ZrO2 nanorods by a simple hydrothermal method and its possible formation mechanism based on a series of chemical reactions have been proposed here. The traditional preparation methods of hierarchical ZrO2 nanorods are involved in expensive equipment, complicated process and high production cost. Owing to their physical and chemical properties hierarchical ZrO2 nanorods have received considerable attention. The results revealed that as synthesized products are composed of many nanorods with 100–200 nm in diameter and 3–5 μm in length. The final product after annealing is involved into hierarchical monoclinic ZrO2 (m-ZrO2) nanorods, the big nanorod was made up of many small nanorods with 30–40 nm in diameter and 350–450 nm in length. This discovery could open a new path to the template-free synthesis of hierarchical nanomaterials.Here a new idea is proposed for template-free synthesis of hierarchical ZrO2 nanorods and its possible formation mechanism.
Co-reporter:JiangHao Liu;WeiMin Wang
Science China Technological Sciences 2014 Volume 57( Issue 6) pp:1085-1092
Publication Date(Web):2014 June
DOI:10.1007/s11431-014-5518-0
The fast densification method of combustion reaction plus quick pressing was adopted to prepare nanocrystalline ceramics. The densification process of magnesia compact with a particle size of 100 nm was investigated, under the applied pressure of up to 170 MPa, and the temperature range of 1740–2080 K with ultra-high heating rate (above 1700 K/min). High-purity magnesia ceramics with a relative density of 98.8% and an average grain size of 120 nm was obtained at 1740 K, and the grain growth during the densification process was effectively restrained. The characteristic morphology of evaporation-condensation was observed in the compact prepared at 2080 K, which revealed the actual process of mass transfer by gas diffusion. Moreover, the investigation on the microstructure evolution and mechanism of grain growth was carried out, on the basis of as-preserved nanocrystalline ceramics. The result indicated that the grain growth of the nanocrystalline MgO was controlled by the mechanism of evaporation-condensation rather than surface diffusion. Furthermore, the pressure had an influence of restraining the grain growth based on solid diffusion and strengthening the effect of gas diffusion with the increasing temperature. Under the particular conditions, there existed an appropriate temperature for the densification of nanocrystalline magnesia, while the excessive temperature would exaggerate grain growth and impede densification.
Co-reporter:ZhengYi Fu;LiWei Huang;JinYong Zhang
Science China Technological Sciences 2012 Volume 55( Issue 2) pp:484-489
Publication Date(Web):2012 February
DOI:10.1007/s11431-011-4674-8
An ultra-fast densification method based on high heating rate from the combustion reaction for producing carbon nanotubes (CNTs) reinforced alumina ceramics is reported. The heat generated by combustion reaction is adopted to act as a high temperature source to the sample, which results in a heating rate of 1660°C/min of the sample. Then a great mechanical pressure is applied to the sample when the sample gets the expected temperature. The densification process is finished in several minutes. The results indicate that the densification method is beneficial to protect the CNTs from destruction and creates good interfacial combination between the nanotubes and the matrix. With the addition of 1 wt% CNTs, the fracture toughness of the ceramics prepared increases about 50%.
Co-reporter:Kuibao Zhang, Zhengyi Fu
Intermetallics 2012 Volume 22() pp:24-32
Publication Date(Web):March 2012
DOI:10.1016/j.intermet.2011.10.010
CoCrFeNiTiAlx (x: molar ratio) high-entropy alloys with different Al content were prepared by vacuum arc-melt casting and the as-synthesized alloys were subsequently heat treated at 1000 °C for 2 h. Effects of Al content and annealing treatment on phase composition and microstructure of these alloys were investigated by intensive characterization and analysis of the crystal structure, morphology and elemental segregation. Al addition promotes the formation of BCC structured phases in both as-cast and as-annealed alloys. The alloy without Al addition is mainly composed of face-centered cubic (FCC) solid-solution while the main phase transforms to stabilized (α-Fe,Cr)-based body-centered cubic (BCC) solid-solution as Al is introduced. Annealing demonstrates no obvious influence on the main phase and elemental segregation of CoCrFeNiTiAlx alloys except for alloys with low Al content (x = 0, 0.5 and 1.0) contain more intermetallic compounds after annealing. The phase formation rules of high-entropy alloys is explored in this study as the empirical formation rules of simple solid-solutions are proposed as: mixing entropy (∆Smix) ≥ 13.38 J/K·mol, −10 kJ/mol ≤ mixing enthalpy (∆Hmix) ≤ 5 kJ/mol and atom-size difference (δ) ≤ 4.
Co-reporter:Kuibao Zhang, Zhengyi Fu, Tadachika Nakayama, Tsuneo Suzuki, Hisayuki Suematsu, Koichi Niihara
Materials Research Bulletin 2011 46(11) pp: 2155-2162
Publication Date(Web):
DOI:10.1016/j.materresbull.2011.04.015
Co-reporter:K.B. Zhang, Z.Y. Fu, J.Y. Zhang, J. Shi, W.M. Wang, H. Wang, Y.C. Wang, Q.J. Zhang
Journal of Alloys and Compounds 2010 Volume 502(Issue 2) pp:295-299
Publication Date(Web):23 July 2010
DOI:10.1016/j.jallcom.2009.11.104
The equiatomic multiprincipal CoCrFeNiCuAl high-entropy alloy was prepared using a vacuum arc melt casting method. The as-cast alloy was subsequently annealed at 1000 °C for 2 h and the annealing effects on the structure and properties evolution were investigated. The as-cast alloy is composed of simple BCC and FCC solid solutions. The “2” FCC phase precipitates from the ordered BCC matrix and the FCC phases become dominated after the alloy was annealed. Both alloys show typical cast-dendrite morphology and similar elemental segregation. The as-annealed alloy exhibits high strength and excellent ductility of 1.63 GPa and 34%, respectively. Both alloys possess high saturated magnetization and undergo a ferromagnetic transition.
Co-reporter:K.B. Zhang, Z.Y. Fu, J.Y. Zhang, W.M. Wang, S.W. Lee, K. Niihara
Journal of Alloys and Compounds 2010 Volume 495(Issue 1) pp:33-38
Publication Date(Web):9 April 2010
DOI:10.1016/j.jallcom.2009.12.010
The equiatomic multicomponent CoCrFeNiTiAl high-entropy solid solution alloy was synthesized by mechanical alloying (MA). The effects of milling duration and subsequent annealing on the structure and morphology evolution were investigated. Supersaturated BCC and FCC solid solutions appear when the blended powder is ball milled more than 18 h. The 30 h ball milled alloy powder shows excellent chemical homogeneity and refined morphology with mean particle size of less than 5 μm. The microscaled particles are actually hard agglomerations of nanoscaled crystallines with crystal size of about 40 nm. The phase composition transforms to two BCC solid solutions when the 30 h mechanically alloyed powder was annealed at 600 °C for 1 h. The simple solid solution structure can be maintained even after the alloy was annealed at 1000 °C. The 30 h milled alloy powder was subsequently consolidated by spark plasma sintering (SPS) at 800 °C for 10 min. The sintered sample Exhibits 98% in relative density and 432 HV in Vickers hardness.
Co-reporter:J. Li, Z.Y. Fu, W.M. Wang, H. Wang, S.H. Lee, K. Niihara
Ceramics International 2010 Volume 36(Issue 5) pp:1681-1686
Publication Date(Web):July 2010
DOI:10.1016/j.ceramint.2010.03.013
Abstract
ZrC fine powder has been prepared by self-propagating high-temperature synthesis (SHS) based on exothermic reduction reaction of ZrO2–C–Mg. The combustion temperature observed was 1979 K. The effects of Mg content and particle size on the combustion temperature and chemical composition of the product were investigated. The reducing agent Mg plays an important role on the purity of ZrC powder obtained by SHS process. Post-heat treatment was applied to decrease the oxygen content of the final product further.
Co-reporter:Fan Zhang, Zhengyi Fu, Jinyong Zhang, Hao Wang, Weimin Wang, Yucheng Wang, Jin Shi
Ceramics International 2010 Volume 36(Issue 4) pp:1491-1494
Publication Date(Web):May 2010
DOI:10.1016/j.ceramint.2010.02.013
Abstract
Boron carbide ceramics were obtained in 2 min by a method based on self-propagating high-temperature synthesis plus quick pressing (SHS/QP). The samples were densified to 98% of theoretical density under a large mechanical pressure (120 MPa) and a fast heating rate (2300 °C/min). The microstructure and mechanical properties were studied. The sample obtained at this heating rate presents an average grain size of 3 μm and a hardness of 34 ± 0.2 GPa.
Co-reporter:Fei Huang, Zhengyi Fu, Aihua Yan, Weimin Wang, Hao Wang, Jinyong Zhang, Qingjie Zhang
Powder Technology 2010 Volume 197(1–2) pp:83-86
Publication Date(Web):10 January 2010
DOI:10.1016/j.powtec.2009.08.023
Co-reporter:Fei Huang, Zhengyi Fu, Weimin Wang, Hao Wang, Yucheng Wang, Jinyong Zhang, Qingjie Zhang, Soo Wohn Lee, Kochi Niihara
Materials Research Bulletin 2010 45(6) pp: 739-743
Publication Date(Web):
DOI:10.1016/j.materresbull.2010.02.005
Co-reporter:Fei Huang, Zhengyi Fu, Aihua Yan, Weimin Wang, Hao Wang, Yucheng Wang, Jinyong Zhang, Yibing Cheng and Qingjie Zhang
Crystal Growth & Design 2009 Volume 9(Issue 9) pp:4017-4022
Publication Date(Web):July 27, 2009
DOI:10.1021/cg900161w
A TiO2/TiB2 heterostructure with a sea-urchin shape, as a new material system, was successfully synthesized by a facile hydrothermal approach in an aqueous solution of ethylenediamine (EDA). This complex architecture is a core/shell urchin structure composed of high-density anatase TiO2 (A-TiO2) nanorod-built networks (shell part) that stand on a TiB2 microcrystal (core part). The microstructure can be controlled by the temperature, time, reactants, and additives. A three-step sequential “oriented attachment growth” model is proposed based on the observations from a time-dependent and temperature-dependent morphology evolution process. Importantly, UV−vis absorption spectra show that the absorption peak and absorption edge has an obvious shift to a lower energy because of the nanometric effect and N-doping.
Co-reporter:K.B. Zhang, Z.Y. Fu, J.Y. Zhang, J. Shi, W.M. Wang, H. Wang, Y.C. Wang, Q.J. Zhang
Journal of Alloys and Compounds 2009 Volume 485(1–2) pp:L31-L34
Publication Date(Web):19 October 2009
DOI:10.1016/j.jallcom.2009.05.144
The equiatomic multicomponent CoCrFeNiCuAl high-entropy solid solution alloy was synthesized by mechanical alloying (MA). The effects of milling duration and subsequent annealing on the morphology and structure evolution were investigated. Supersaturated solid solution structure can be obtained when the blended powder is ball milled longer than 42 h. The 60 h ball milled alloy powder shows refined morphology and excellent chemical homogeneity. The 60 h ball milled powder exhibits mean particle size of less than 5 μm, which are actually hard agglomerations of nanosized crystalline with crystal size of less than 50 nm. A BCC and a FCC solid solution structure phases appear when the 60 h mechanically alloyed powder was annealed at 600 °C for 1 h, which is attributed to phase precipitation of the metastable supersaturated solid solution. The simple solid solution structure can be maintained even after annealed at 1000 °C.
Co-reporter:Fei Huang, Zhengyi Fu, Aihua Yan, Weimin Wang, Hao Wang, Yucheng Wang, Jinyong Zhang, Qinjie Zhang
Materials Letters 2009 Volume 63(Issue 30) pp:2655-2658
Publication Date(Web):31 December 2009
DOI:10.1016/j.matlet.2009.09.027
Several kinds of TiO2/TiB2 hybrid materials with different morphologies, including hollow bipyramid structure with truncations, pineapple structure, urchin structure and nanowall structure, have been successfully synthesized by a facile solvothermal approach in the aqueous solution of ethylenediamine. The effect of ethylene ediamine on the shape change of the final products was investigated in detail. With the increase of ethylenediamine, anatase TiO2 on the TiB2 core is gradually evolved from nanoparticles, nanorods to nanosheets. Based on attachment theory, Oswald ripening phenomenon, chelating effect and Kirkendall effect, a possible formation mechanism for such TiO2/TiB2 hybrid materials was proposed to explain the morphology evolution.
Co-reporter:K.B. Zhang, Z.Y. Fu, J.Y. Zhang, W.M. Wang, H. Wang, Y.C. Wang, Q.J. Zhang, J. Shi
Materials Science and Engineering: A 2009 Volume 508(1–2) pp:214-219
Publication Date(Web):20 May 2009
DOI:10.1016/j.msea.2008.12.053
CoCrFeNiTiAlx (x values in molar ratio, x = 0, 0.5, 1.0, 1.5 and 2.0) high-entropy alloys were prepared using a vacuum arc melting method. The effects of Al addition on microstructure and mechanical properties were investigated. The results show that only a face-centered cubic (FCC) crystal structure phase is observed in the CoCrFeNiTi alloy. The phase composition transforms to stabilized body-centered cubic (BCC) structure phases and typically cast dendrite structure appears when Al is added. The dendrite region is rich in Co, Ni, Ti and Al elements while the interdendrite region is rich in Fe and Cr elements. Subgrains and nanosized precipitates are observed in the as-cast CoCrFeNiTiAl alloy. These CoCrFeNiTiAlx high-entropy alloys exhibit excellent room-temperature mechanical properties. For CoCrFeNiTiAl1.0 alloy, the compressive strength and elastic modulus reach as high as 2.28 GPa and 147.6 GPa, respectively. High density of dimple-like structure is observed from the fracture surfaces of the Al0 alloy, while alloys with Al addition show typical cleavage fractures with river-like patterns and cleavage steps.
Co-reporter:Yanli Su 苏艳丽 傅正义;Peiyan Ma
Journal of Wuhan University of Technology-Mater. Sci. Ed. 2009 Volume 24( Issue 6) pp:
Publication Date(Web):2009 December
DOI:10.1007/s11595-009-6973-5
In order to improve the bioavailability, Radix salvia miltiorrhiza raw powder mixed with distilled water (5.5wt%) was ultrafinely ground to nanosize particles using HSCS pulverizer, and the dissolving-out quantity of tanshinone IIA in the filtrate that obtained from nanoparticles suspension and raw powder marinated in water for different time was determined by HPLC. The experimental results show that raw powder can be ultrafinely ground to 133.5 nm at 1500 r/min for 50 min and the molecular structure of active ingredients doesnot change, and the dissolving-out quantity of tanshinone IIA obtained from the filtrate is increased greatly from 12.77 µg/g to 54.55 µg/g.
Co-reporter:Hui Zeng, Jingjing Xie, Hao Xie, Bao-Lian Su, Menghu Wang, Hang Ping, Weimin Wang, Hao Wang and Zhengyi Fu
Journal of Materials Chemistry A 2015 - vol. 3(Issue 38) pp:NaN19596-19596
Publication Date(Web):2015/08/24
DOI:10.1039/C5TA04649A
Inspired by the structure-forming process of biominerals, scientists have been successful in synthesizing materials with elegant structures by using organic matrices as templates. However, there are still issues relating to the exquisiteness and complexity of natural organic matrices in living organisms which have kept their activities out of chemists' control, in particular the functional properties of such materials. Here we employ natural assorted proteins, which are derived from the extrapallial fluid in living mussels, to synthesize hierarchically porous nitrogen-doped TiO2 in a single process. The silk-like organic residues in the powders clearly show that the proteins act to segment the space for TiO2 nucleation. We also demonstrate phase control over the material, with the ability to synthesize pure anatase. The synthesized TiO2 materials show a significant improvement in visible-light photocatalytic activity for both the degradation of organic pollutants and hydrogen production. The degradation of RhB could be almost completed in just 20 min. The visible-light photocatalytic activities vary with the concentrations of EPF proteins, and the optimal concentration of protein was found to be 600 μg mL−1. The present work highlights its potential application as a natural organic matrix in producing advanced materials with optimized functional properties.
Co-reporter:Hang Ping, Hao Xie, Bao-Lian Su, Yi-bing Cheng, Weimin Wang, Hao Wang, Yucheng Wang, Jinyong Zhang, Fan Zhang and Zhengyi Fu
Journal of Materials Chemistry A 2015 - vol. 3(Issue 22) pp:NaN4502-4502
Publication Date(Web):2015/05/01
DOI:10.1039/C5TB00386E
Taking lessons from the structure-forming process of biominerals in animals and plants, one can find tremendous inspirations and ideas for developing advanced synthesis techniques, which is called bio-process inspired synthesis. Bone, as a typical representative of biominerals, is constituted of mineralized collagen fibrils, which are formed under the functions of non-collagenous proteins (NCPs). Intrafibrillar mineralization is the consequence of a synergy among several NCPs. In the present study, we have designed a multi-functional protein, named (MBP)–BSP–HAP, based on bone sialoprotein (BSP) and hydroxyapatite binding protein (HAP), to mimic the intrafibrillar mineralization process in vitro. The three functional domains of (MBP)–BSP–HAP provide the artificial protein with multiple designated functions for intrafibrillar mineralization including binding calcium ions, binding collagen, and binding hydroxyapatite. Platelet-like hydroxyapatite crystals periodically arranged inside the collagen fibrils have been achieved under the function of (MBP)–BSP–HAP. The mechanism of intrafibrillar mineralization directed by the multi-functional protein was proposed. This work may not only shed light on bio-process inspired approaches for more economic and efficient biomimetic synthesis, but also be helpful in understanding the natural process of bone formation for bone regeneration and tissue repair.
Co-reporter:X.-L. Wang, H. Xie, B.-L. Su, Y.-B. Cheng, J.-J. Xie, H. Ping, M.-H. Wang, J.-Y. Zhang, F. Zhang and Z.-Y. Fu
Journal of Materials Chemistry A 2015 - vol. 3(Issue 29) pp:NaN5956-5956
Publication Date(Web):2015/06/09
DOI:10.1039/C5TB00650C
Living organisms can produce elegant structures with unique functions and properties through biological processes. Various proteins are involved in these processes. Inspired by the structure formation of mollusc shells, a single multifunctional recombinant protein ChiCaSifi was designed on the basis of mineralization proteins for regulating CaCO3 mineralization in a simple and direct manner. ChiCaSifi contains functional domains of the chitin binding protein (Chi), the calcium binding protein (Ca), and the silk fibroin (Sifi). Therefore, ChiCaSifi can have multiple roles in directing CaCO3 mineralization. Overexpression and purification of ChiCaSifi were achieved. Activities of ChiCaSifi were examined for its binding to calcium and chitin. Influences of ChiCaSifi in regulating the phase formation of CaCO3 crystals on the chitin surface were proved. Structural changes of ChiCaSifi were evidenced and related to its functions on mineralization. These observations indicate that rationally designed proteins with functional domains of mineralization proteins can be effective tools in materials synthesis. The present study may not only provide an insight into the formation of natural biomaterials, but also open a new avenue in the design and synthesis of novel organic–inorganic composite materials.
Co-reporter:Hang Ping, Hao Xie, Yamin Wan, Zhixiao Zhang, Jing Zhang, Mingyu Xiang, Jingjing Xie, Hao Wang, Weimin Wang and Zhengyi Fu
Journal of Materials Chemistry A 2016 - vol. 4(Issue 5) pp:NaN886-886
Publication Date(Web):2015/12/18
DOI:10.1039/C5TB01990G
Confinement is common in biological systems and plays a critical role in the structure-forming process of biominerals. However, the knowledge of confinement effects on biomineralization is limited due to the lack of specific chemical structures and elaborate spatial distribution. In this article, we explore the confined mineralization of amorphous calcium carbonate (ACC) within collagen fibrils. Three issues of the confined mineralization of ACC within collagen fibrils were investigated, including the morphology and characteristics of the confined mineralization of ACC within collagen fibrils; the initiation and development of the confined mineralization of ACC within collagen fibrils; and the driving mechanism of ACC infiltration into collagen fibrils. Results show that the negatively charged ACC droplets were attracted to positively charged gap regions of collagen fibrils through electrostatic interactions, infiltrated into collagen fibrils, and then transformed into the crystalline phase. The observation of juxtaposed crystalline and amorphous phases on the surface of fibrils indicates that a secondary nucleation mechanism may be responsible for the co-orientation of calcite nanocrystals. Through modifying the wettability of amorphous calcium carbonate with magnesium ions, it is verified that the infiltration of ACC into collagen fibrils was driven by capillary forces. The present study not only provides evidence of the confinement effects in biomineralization but also facilitates the understanding of the in vivo bone formation process. It may also open up a new avenue in the bioprocess-inspired synthesis of advanced materials.
Co-reporter:Tiening Tan, Hao Xie, Jingjing Xie, Hang Ping, Bao-Lian Su, Weimin Wang, Hao Wang, Zuhair A. Munir and Zhengyi Fu
Journal of Materials Chemistry A 2016 - vol. 4(Issue 48) pp:NaN18989-18989
Publication Date(Web):2016/11/11
DOI:10.1039/C6TA07314J
Surface composition control plays a crucial role in electrocatalytic reactions for Pt-based bimetallic materials. However, strategies for controlling their surface composition always require extreme conditions including the use of harsh agents, the need for high temperatures, and the necessity of complex procedures. Here we develop a photo-assisted method to fabricate Au@PtAu core–shell nanoparticles (NPs) with well-tuned surface composition at ambient temperatures. It was found that their surface composition can be continuously regulated by the addition amount of HAuCl4 under photo-irradiation. By incorporating Au atoms, the synthesized Au@PtAu NPs show significantly improved properties for methanol electro-oxidation, owing to the reduced CO formation and the weakened binding strength of CO on Pt. The catalytic activity and durability vary with the relative active surface area of Pt or Au (PtSurf. or AuSurf.), and the optimal PtSurf. was found to be ∼64% (AuSurf. ∼36%). The present work highlights the “photo-assisted method” as a green and effective method to synthesize advanced materials with optimized functional properties.
Co-reporter:Hang Ping, Hao Xie, Mingyu Xiang, Bao-Lian Su, Yucheng Wang, Jinyong Zhang, Fan Zhang and Zhengyi Fu
Chemical Science (2010-Present) 2016 - vol. 7(Issue 10) pp:NaN6336-6336
Publication Date(Web):2016/07/14
DOI:10.1039/C6SC02311H
Biomineral formation processes in nature are temporally and spatially regulated under the functions of biomolecules in a confined space. It is potentially very productive to rationally design a mineralized system by taking into account confined space as well as biomolecules. The laboratory technique of “bacterial cell surface display” is an ideal platform to host catalytically active proteins in a three-dimensionally confined space. In the present study, aiming to regulate the synthesis of nanostructured TiO2 anatase, repeating segments of silaffin were displayed on Escherichia coli surfaces through genetic manipulation. The displayed protein electrostatically interacted with a titanium source and catalyzed the hydrolysis of titanium dioxide precursors through hydrogen bonding interactions on the cell surface. In the subsequent calcination process, the genetically modified cells not only served as a framework for producing rod-shaped TiO2 assembled by nanoparticles, but also provided a carbon source in situ. The size of nanoparticles was controlled by changing the number of tandem repeats of the protein segment. The as prepared TiO2 anatase exhibited unique characteristics including nanosized anatase crystals, mesoporous structure and carbon coating. When tested as the anode electrode of a lithium-ion battery, it showed excellent lithium storage performance. The carbon coated anatase anode shows a higher specific capacity of 207 mA h g−1 after 200 cycles at a current rate of 1C and an ultra-long cycling lifetime of 5000 cycles with an outstanding retention capacity of 149 mA h g−1 at a higher rate of 10C. This bioprocess-inspired approach may help broaden the scope and impact of nanosized biominerals.
