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44 results on '"Gao, Wen-Kun"'

43. In situconstruction of surface defects of carbon-doped ternary cobalt-nickel-iron phosphide nanocubes for efficient overall water splitting

Author

Gao, Wen-Kun, Yang, Min, Chi, Jing-Qi, Zhang, Xin-Yu, Xie, Jing-Yi, Guo, Bao-Yu, Wang, Lei, Chai, Yong-Ming, and Dong, Bin

Abstract

The ternary cobalt-nickel-iron phosphide nanocubes (P-Co0.9Ni0.9Fe1.2NCs) with high intrinsic activity, conductivity, defect concentration and optimized ratio have been realized through a facile phosphorization treatment using ternary cobalt-nickel-iron nanocubes of Prussian blue analogs (PBA) as a precursor. The scanning electron microscopy and transmission electron microscopy results show that the P-Co0.9Ni0.9Fe1.2NCs maintain a cubic structure with a rough surface, implying the rich surface defects as exposed active sites. The thermal phosphorization of the ternary PBA precursor not only provids carbon doping but also leads to the in situconstruction of surface defects on the NCs. The carbon doping from the PBA precursor lowers the charge transfer resistance and optimizes the electronic transformation. The synergistic effect among the ternary metal ions and rich defects contributes to the enhanced electrocatalytic performance. The P-Co0.9Ni0.9Fe1.2NCs achieve low overpotentials of −200.7 and 273.1 mV at a current density of 10 mA cm−2for the hydrogen evolution reaction and the oxygen evolution reaction, respectively. The potential of overall water splitting reaches 1.52 V at a current density of 10 mA cm−2. The long-term stability of the electrocatalysts was also evaluated. This work provides a facile method to design efficient transition-metal-based bifunctional electrocatalysts for overall water splitting. 本文以三元金属钴-镍-铁普鲁士蓝结构纳米立方体(Co0.9-Ni0.9Fe1.2NCs)为前驱体, 通过简单气相磷化处理, 得到优化比例的 P-Co0.9Ni0.9Fe1.2纳米立方体磷化物, 其具有高本征活性、导电性和高缺陷密度的特点. SEM和TEM结果表明, 碳掺杂型 P-Co0.9Ni0.9-Fe1.2保持了纳米立方体的结构, 其粗糙的表面结构意味着丰富的缺陷位, 暴露更多真实活性位. 三元金属普鲁士蓝前驱体的磷化处理不仅提供了碳掺杂, 而且原位构筑了立方体表面缺陷位. 碳掺杂降低了电荷传输的阻抗, 优化了电子传输速率. 三元金属离子之间的协同作用以及丰富的缺陷活性位有效提高了电催化的性能. P-Co0.9Ni0.9Fe1.2拥有极其高的HER和OER催化活性, 仅需要 −200.7 mV (HER) 和273.1 mV (OER) 过电位就可以达到 10 mA cm−2 的电流密度. 其全水分解仅需1.52 V就可以达到10 mA cm−2的电流密度. 此外, 本文还对催化剂的稳定性进行了测试. 本工作为设计高效过渡金属基双功能电解水催化剂提供了一种简便方法.

Published
2019
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44. In situ sulfurized CoMoS/CoMoO4 shell–core nanorods supported on N-doped reduced graphene oxide (NRGO) as efficient electrocatalyst for hydrogen evolution reaction.

Author

Liu, Yan-Ru, Shang, Xiao, Gao, Wen-Kun, Dong, Bin, Li, Xiao, Li, Xue-Hui, Zhao, Jin-Chong, Chai, Yong-Ming, Liu, Yun-Qi, and Liu, Chen-Guang

Abstract

Many strategies, such as doping metal, designing low-dimensional nanostructures, and enhancing the utilization of active sites based on a conductive support, have been intensively pursued to improve the intrinsic activity of transition metal chalcogenides for the hydrogen evolution reaction (HER). However, integrating all the above-mentioned merits into one electrocatalyst is still a significant challenge. Herein, we have successfully prepared uniform CoMoS/CoMoO4 (CMS) shell–core nanorods, with a diameter of 60 nm and a length of 800 nm, supported on N-doped reduced graphene oxide (NRGO). The obtained CMS/NRGO can combine many advantages, including transition metal doping, one-dimensional nanorods, and the superior conductivity of NRGO, resulting in very promising HER properties and excellent stability. The optimum sulfurization temperature for unsupported CMS nanorods has been explored using uniform CoMoO4 nanorods as a precursor. Although CMS-3 prepared with a sulfurization temperature of 300 °C has been found to possess the optimum activity for the HER, when adopting NRGO as a support, CMS-3/NRGO exhibits an impressive enhancement in HER performances with a low overpotential of 80 mV, a small Tafel slope of 58 mV dec−1, and a large exchange current density of 428 μA cm−2. In addition, the electrocatalytic activity of CMS-3/NRGO shows a negligible delay after 1000 cycles, indicating its robust electrochemical stability in acid electrolyte solution. Therefore, adopting low-temperature sulfurization of one-dimensional metal oxide precursors supported on NRGO may be a promising strategy for obtaining excellent electrocatalysts for the HER. [ABSTRACT FROM AUTHOR]

Published
2017
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