Nanopolygons of Monolayer MS<sub>2</sub>: Best Morphology and Size for HER Catalysis.
basic_science · Level V
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- Record sourced from PubMed, PMID 27936804.
- Also identified by DOI 10.1021/acs.nanolett.6b04324.
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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-MS<sub>2</sub>, 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-MS<sub>2</sub> performance, we identify three keys in making npm-MS<sub>2</sub> with optimal HER performance: (a) npm-MS<sub>2</sub> should be triangular with each edge being M-terminated and each edge-M atom passivated by one S atom; (b) each edge of npm-MoS<sub>2</sub> and WS<sub>2</sub> should 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-VS<sub>2</sub> is immune to this overly fastidious size dependence. Known experimental data on npm-MoS<sub>2</sub> indeed 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-MS<sub>2</sub> are critical but practical. Research on npm-VS<sub>2</sub> would bear the highest impact because of its size-forgiving HER performance and relatively high abundance and low cost.