期刊
NANO ENERGY
卷 70, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.nanoen.2020.104445
关键词
Electrocatalysis; Hydrogen evolution reaction; Transition metal phosphide; Density functional theory; Hybrid nanostructures
类别
资金
- National Natural Science Foundation of China [21975129]
- Natural Science Foundation of Jiangsu Province [BK20190759]
- Natural Science Foundation of Jiangsu Higher Education Institutions of China [19KJB430003]
- Science Fund for Distinguished Young Scholars
- Landmark Achievement Cultivation Project
- Start-up Fund, Nanjing Forestry University
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 Delta G(H*) of Ni/Co doped MoP at the Mo site is lower than that at the P site, and the lowest Delta G(H*) 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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