过电位
塔菲尔方程
材料科学
磷化物
催化作用
过渡金属
分解水
化学工程
无机化学
纳米颗粒
电化学
电催化剂
兴奋剂
纳米技术
金属
物理化学
电极
化学
冶金
有机化学
工程类
光催化
光电子学
作者
Weiping Xiao,Lin Zhang,Danil Bukhvalov,Zupeng Chen,Zhaoyong Zou,Lu Shang,Xiaofei Yang,Daqiang Yan,Fengyan Han,Tierui Zhang
出处
期刊:Nano Energy
[Elsevier]
日期:2020-04-01
卷期号:70: 104445-104445
被引量:120
标识
DOI:10.1016/j.nanoen.2020.104445
摘要
Molybdenum phosphide (MoP) has been recognized as a promising family of non-noble metal electrocatalysts for hydrogen evolution reaction (HER) by water splitting, but their electrocatalytic HER activities are still far from desirable and the active sites of MoP-based electrocatalysts have rarely been explored. Herein, we demonstrate a novel hybrid nanostructure composed of carbon encapsulating ultra-low Co/Ni-doped MoP nanoparticles, which can be adopted as highly active and stable HER catalysts in pH-universal electrolytes. The optimized carbon-encapsulated MoP nanoparticles with a Ni/Mo molar ratio of 0.02 achieve a low overpotential of 102 mV at 10 mA cm−2 and a small Tafel slope of 58.1 mV dec−1 in 0.5 M H2SO4 solution, outperforming most of previously reported MoP-based electrocatalysts. More importantly, density functional theory based calculations reveal that the △GH* of Ni/Co doped MoP at the Mo site is lower than that at the P site, and the lowest △GH* of the doping form of Ni and Co at Mo site was interstitial and substitutional + interstitial, respectively. Higher catalytic performance is observed on doped Mo-terminated surface especially in the presence of non-stoichiometric Ni and Co defects. The lowest free energy of Ni-doping implies that Ni-doped MoP hybrid nanostructures possess weak hydrogen adsorption energy and excellent HER catalytic activity in a wide pH range. The combined experimental and theoretical study paves the way for the identification of the active sites in MoP-based hybrid electrocatalysts toward high-performance HER.
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