The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Ping Jin - One of the best experts on this subject based on the ideXlab platform.
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room temperature synthesis of inorganic organic hybrid coated vo2 nanoparticles for Enhanced Durability and flexible temperature responsive near infrared modulator application
ACS Applied Materials & Interfaces, 2019Co-Authors: Shuwen Zhao, Yunxiang Chen, Ying Tao, Yijie Zhou, Lingling Xie, Aibin Huang, Ping JinAbstract:Vanadium dioxide is one kind of desirable infrared modulator for sensors because of its remarkable temperature-responsive infrared modulation ability via autogeneic metal–insulator transition. Howe...
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effects of v2o3 buffer layers on sputtered vo2 smart windows improved thermochromic properties tunable width of hysteresis loops and Enhanced Durability
Applied Surface Science, 2018Co-Authors: Shiwei Long, Ping Jin, Xun Cao, Guangyao Sun, Tianci Chang, Zewei ShaoAbstract:Abstract Vanadium dioxide (VO2) is one of the most well-known thermochromic materials, which exhibits a notable optical change from transparent to reflecting in the infrared region upon a metal-insulator phase transition. For practical applications, VO2 thin films should be in high crystalline quality to obtain a strong solar modulation ability (ΔTsol). Meanwhile, narrow hysteresis loops and robust ambient Durability are also indispensable for sensitivity and long-lived utilization, respectively. In this work, a series of high-quality V2O3/VO2 bilayer structures were grown on quartz glass substrates by reactive magnetron sputtering. Basically, the bottom V2O3 acts as the buffer layer to improve the crystallinity of the top VO2, while the VO2 serves as the thermochromic layer to guarantee the solar modulation ability for energy-saving. We observed an obvious increase in ΔTsol of 76% (from 7.5% to 13.2%) for VO2 films after introducing V2O3 buffer layers. Simultaneously, a remarkable reduction by 79% (from 21.9 °C to 4.7 °C) in width of hysteresis loop was obtained when embedding 60 nm V2O3 buffer for 60 nm VO2. In addition, VO2 with non-stoichiometry of V2O3±x buffer demonstrates a broadening hysteresis loops width, which is derived from the lattice distortion caused by lattice imperfection. Finally, Durability of VO2 has been significantly improved due to positive effects of V2O3 buffer layer. Our results lead to a comprehensive enhancement in crystallinity of VO2 and shed new light on the promotion of thermochromic property by homologous oxides for VO2.
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effects of v 2 o 3 buffer layers on sputtered vo 2 smart windows improved thermochromic properties tunable width of hysteresis loops and Enhanced Durability
Applied Surface Science, 2018Co-Authors: Shiwei Long, Ping Jin, Xun Cao, Guangyao Sun, Tianci Chang, Zewei ShaoAbstract:Abstract Vanadium dioxide (VO2) is one of the most well-known thermochromic materials, which exhibits a notable optical change from transparent to reflecting in the infrared region upon a metal-insulator phase transition. For practical applications, VO2 thin films should be in high crystalline quality to obtain a strong solar modulation ability (ΔTsol). Meanwhile, narrow hysteresis loops and robust ambient Durability are also indispensable for sensitivity and long-lived utilization, respectively. In this work, a series of high-quality V2O3/VO2 bilayer structures were grown on quartz glass substrates by reactive magnetron sputtering. Basically, the bottom V2O3 acts as the buffer layer to improve the crystallinity of the top VO2, while the VO2 serves as the thermochromic layer to guarantee the solar modulation ability for energy-saving. We observed an obvious increase in ΔTsol of 76% (from 7.5% to 13.2%) for VO2 films after introducing V2O3 buffer layers. Simultaneously, a remarkable reduction by 79% (from 21.9 °C to 4.7 °C) in width of hysteresis loop was obtained when embedding 60 nm V2O3 buffer for 60 nm VO2. In addition, VO2 with non-stoichiometry of V2O3±x buffer demonstrates a broadening hysteresis loops width, which is derived from the lattice distortion caused by lattice imperfection. Finally, Durability of VO2 has been significantly improved due to positive effects of V2O3 buffer layer. Our results lead to a comprehensive enhancement in crystallinity of VO2 and shed new light on the promotion of thermochromic property by homologous oxides for VO2.
Bowen Qin - One of the best experts on this subject based on the ideXlab platform.
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carbon supported ultrafine pt nanoparticles modified with trace amounts of cobalt as Enhanced oxygen reduction reaction catalysts for proton exchange membrane fuel cells
Chinese Journal of Catalysis, 2019Co-Authors: Xuejun Tang, Dahui Fang, Lijuan Qu, Dongyan Xu, Xiaoping Qin, Bowen QinAbstract:Abstract To accelerate the kinetics of the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells, ultrafine Pt nanoparticles modified with trace amounts of cobalt were fabricated and decorated on carbon black through a strategy involving modified glycol reduction and chemical etching. The obtained Pt36Co/C catalyst exhibits a much larger electrochemical surface area (ECSA) and an improved ORR electrocatalytic activity compared to commercial Pt/C. Moreover, an electrode prepared with Pt36Co/C was further evaluated under H2-air single cell test conditions, and exhibited a maximum specific power density of 10.27 W mgPt−1, which is 1.61 times higher than that of a conventional Pt/C electrode and also competitive with most state-of-the-art Pt-based architectures. In addition, the changes in ECSA, power density, and reacting resistance during the accelerated degradation process further demonstrate the Enhanced Durability of the Pt36Co/C electrode. The superior performance observed in this work can be attributed to the synergy between the ultrasmall size and homogeneous distribution of catalyst nanoparticles, bimetallic ligand and electronic effects, and the dissolution of unstable Co with the rearrangement of surface structure brought about by acid etching. Furthermore, the accessible raw materials and simplified operating procedures involved in the fabrication process would result in great cost-effectiveness for practical applications of PEMFCs.
Yu Seung Kim - One of the best experts on this subject based on the ideXlab platform.
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a rejuvenation process to enhance the Durability of low pt loaded polymer electrolyte membrane fuel cells
Journal of Power Sources, 2018Co-Authors: David A Langlois, Albert S Lee, Natalia Macauley, Sandip Maurya, M E Hawley, Sungdae Yim, Yu Seung KimAbstract:Abstract An effective method to enhance the Durability of polymer electrolyte membrane fuel cells (PEMFCs) is reported. PEMFC performance loss is mitigated by exposing the electrodes of fuel cells to dry nitrogen gas periodically at high temperature. This method extends the lifetime of fuel cells significantly compared to their non-treated counterparts. The impact of treatment temperature and exposure time on PEMFC Durability is reported, using potential cycling accelerated stress tests. The Enhanced Durability is attributed to the suppression of “ionomer relaxation” that occurs under the nearly water saturated operating conditions of a PEMFC cathode.
Huamin Zhang - One of the best experts on this subject based on the ideXlab platform.
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effect of particle size on the activity and Durability of the pt c electrocatalyst for proton exchange membrane fuel cells
Applied Catalysis B-environmental, 2012Co-Authors: Huamin Zhang, Hexiang Zhong, Yunfeng WangAbstract:Carbon supported Pt (Pt/C) with various average particle sizes ranging from sub 3 nm to 6.5 nm were in situ prepared and characterized at the cathode of proton exchange membrane fuel cells (PEMFCs). A clear Pt particle size effect on both the catalytic activity for oxygen reduction reaction (ORR) and the Durability of the electrocatalyst was revealed. With the Pt particle size increase, both the surface specific activity and the electrochemical stability of Pt/C improved; however, the mass specific activity of Pt/C is balanced by the electrochemical surface area loss. The reduced occupation of corner and edge atoms on the Pt surface during the Pt particle size increase is believed to weaken the adsorption of the oxygenated species on Pt, and thereafter releases more available active sites for ORR and also renders the Pt surface a stronger resistance against potential cycling. It is therefore proposed that by designing the Pt microstructure with more face atoms on the surface, cathode electrocatalyst with both improved activity and Enhanced Durability would be developed for PEMFCs. (C) 2011 Elsevier B.V. All rights reserved.
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a novel h3po4 nafion pbi composite membrane for Enhanced Durability of high temperature pem fuel cells
Journal of Power Sources, 2007Co-Authors: Yunfeng Zhai, Huamin Zhang, Yu Zhang, Danmin XingAbstract:Abstract A novel phosphoric acid doped Nafion–polybenzimidazole (H 3 PO 4 /Nafion–PBI) composite membrane was prepared and the H 2 /O 2 single cell Durability was tested at 150 °C without humidification. The Durability was improved 55% compared with that of phosphoric acid doped polybenzimidazole (H 3 PO 4 /PBI). During the Durability test, the hydrogen permeability of the membrane and the internal resistance of the single cell were detected using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS), respectively. Before and after the Durability test, the mechanical strength of the membranes was measured by stress–strain tests. The results of characterization indicated that the Enhanced Durability of the membrane attributed to the improved mechanical strength, which benefited from the presence of Nafion in the Nafion and PBI matrix. The preliminary results suggested that the novel H 3 PO 4 /Nafion–PBI composite membrane is a good candidate in high temperature PEMFC for achieving longer cell lifetime.
Yumin Zhang - One of the best experts on this subject based on the ideXlab platform.
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Direct Transformation from Graphitic C3N4 to Nitrogen-Doped Graphene: An Efficient Metal-Free Electrocatalyst for Oxygen Reduction Reaction
ACS Applied Materials & Interfaces, 2015Co-Authors: Jiajie Li, Jikang Jian, Zhihua Zhang, Xianjie Wang, Yumin Zhang, Lin Gu, Yi Wang, Ping XuAbstract:Carbon-based nanomaterials provide an attractive perspective to replace precious Pt-based electrocatalysts for oxygen reduction reaction (ORR) to enhance the practical applications of fuel cells. Herein, we demonstrate a one-pot direct transformation from graphitic-phase C3N4 (g-C3N4) to nitrogen-doped graphene. g-C3N4, containing only C and N elements, acts as a self-sacrificing template to construct the framework of nitrogen-doped graphene. The relative contents of graphitic and pyridinic-N can be well-tuned by the controlled annealing process. The resulting nitrogen-doped graphene materials show excellent electrocatalytic activity toward ORR, and much Enhanced Durability and tolerance to methanol in contrast to the conventional Pt/C electrocatalyst in alkaline medium. It is determined that a higher content of N does not necessarily lead to Enhanced electrocatalytic activity; rather, at a relatively low N content and a high ratio of graphitic-N/pyridinic-N, the nitrogen-doped graphene obtained by anneal...
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direct transformation from graphitic c3n4 to nitrogen doped graphene an efficient metal free electrocatalyst for oxygen reduction reaction
ACS Applied Materials & Interfaces, 2015Co-Authors: Yumin Zhang, Jikang Jian, Zhihua Zhang, Xianjie Wang, Yi Wang, Xinghong Zhang, Jiecai Han, Bo SongAbstract:Carbon-based nanomaterials provide an attractive perspective to replace precious Pt-based electrocatalysts for oxygen reduction reaction (ORR) to enhance the practical applications of fuel cells. Herein, we demonstrate a one-pot direct transformation from graphitic-phase C3N4 (g-C3N4) to nitrogen-doped graphene. g-C3N4, containing only C and N elements, acts as a self-sacrificing template to construct the framework of nitrogen-doped graphene. The relative contents of graphitic and pyridinic-N can be well-tuned by the controlled annealing process. The resulting nitrogen-doped graphene materials show excellent electrocatalytic activity toward ORR, and much Enhanced Durability and tolerance to methanol in contrast to the conventional Pt/C electrocatalyst in alkaline medium. It is determined that a higher content of N does not necessarily lead to Enhanced electrocatalytic activity; rather, at a relatively low N content and a high ratio of graphitic-N/pyridinic-N, the nitrogen-doped graphene obtained by annealing at 900 °C (NGA900) provides the most promising activity for ORR. This study may provide further useful insights on the nature of ORR catalysis of carbon-based materials.