title: Nanopolygons of Monolayer MS2: Best Morphology and Size for HER Catalysis.
abstract: With first-principles calculations, we find a new strategy for developing high-performance catalysts for hydrogen evolution reaction (HER) via controlling the morphology and size of nanopolygons of monolayer transition-metal dichalcogenides (npm-MS2, with M = Mo, W, or V). Particularly, through devising a quantitative method to measure HER-active sites per unit mass and using such HER site density to comparatively gauge npm-MS2performance, we identify three keys in making npm-MS2with optimal HER performance: (a) npm-MS2should be triangular with each edge being M-terminated and each edge-M atom passivated by one S atom; (b) each edge of npm-MoS2and WS2should have 5-6 metal atoms as HER site density drops below/above these sizes optimal both for HER and practical npm growth; and (c) npm-VS2is immune to this overly fastidious size dependence. Known experimental data on npm-MoS2indeed support the plausibility of practicing these design rules. We expect that raising the nucleation density and controlling the growth time to favor the production of our proposed ultrasmall npm-MS2are critical but practical. Research on npm-VS2would bear the highest impact because of its size-forgiving HER performance and relatively high abundance and low cost.
authors.affiliation: State Key Laboratory of Solidification Processing, School of Material Science and Engineering, Northwestern Polytechnical University , 127 YouYi Western Road, Xi'an, Shaanxi 710072, China.
authors.forename: Yu-Rong
authors.initials: YR
authors.lastname: An
authors.affiliation: State Key Laboratory of Solidification Processing, School of Material Science and Engineering, Northwestern Polytechnical University , 127 YouYi Western Road, Xi'an, Shaanxi 710072, China.|Center for Green Innovation, School of Mathematics and Physics, University of Science & Technology Beijing , Beijing 100083, China.
authors.forename: Xiao-Li
authors.identifier: 0000-0002-5291-0706
authors.initials: XL
authors.lastname: Fan
authors.affiliation: State Key Laboratory of Solidification Processing, School of Material Science and Engineering, Northwestern Polytechnical University , 127 YouYi Western Road, Xi'an, Shaanxi 710072, China.
authors.forename: Zhi-Fen
authors.initials: ZF
authors.lastname: Luo
authors.affiliation: Center for Green Innovation, School of Mathematics and Physics, University of Science & Technology Beijing , Beijing 100083, China.
authors.forename: Woon-Ming
authors.initials: WM
authors.lastname: Lau
keywords: Transition-metal dichalcogenides; edge sites; hydrogen evolution reaction; nanopolygons; shape; size