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-MS, 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 performance, we identify three keys in making npm-MS with optimal HER performance: (a) npm-MS 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 and WS 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 is immune to this overly fastidious size dependence. Known experimental data on npm-MoS 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 are critical but practical. Research on npm-VS would bear the highest impact because of its size-forgiving HER performance and relatively high abundance and low cost.

Direct Growth of MoS2 Nanowalls on Carbon Nanofibers for Use in Supercapacitor

“…The unsaturated S atoms on the edge sites from either their atomic structure of H phase or structural defect represent the microstructure having low coordination numbers, hence making the edges more reactive than basal plane 44, 45 . Furthermore, the edge sites also show metallic phase and therefore accommodate ions, making them more reactive too 44 . Consequently, thermodynamic driving force makes the MoS 2 to grow vertically to the fiber or RGO, as shown in Fig.…”

Prereduction of Metal Oxides via Carbon Plasma Treatment for Efficient and Stable Electrocatalytic Hydrogen Evolution

“…In the past few decades, intensive research efforts have been focused on transition metal‐based materials, such as nitrides, carbides, sulfides, phosphides, as efficient candidates for HER catalysts due to their low cost, earth abundance, and optimal strength of metal hydride bond (M‐H). Nevertheless, most of the above catalysts are fabricated from high‐temperature annealing in harsh environments that involve poisonous feedstock and byproduct.…”

Polarized Raman spectroscopy to elucidate the texture of synthesized MoS2

“…Layered 2D transition-metal dichalcogenides (TMDs) are a class of promising materials with applications in the fields of catalysis, photonics, opto-and nano-electronics. [1][2][3][4][5][6][7][8] Excellent transistor characteristics and logic performance have already been demonstrated for mono and few layered TMDs obtained by exfoliation and outstanding catalytic performance has also been shown for TMD films. 4,[9][10][11][12][13] However, in order to adopt these materials in the field of nanoelectronics, the development of scalable synthesis methods for 2D TMDs such as MoS 2 and WS 2 are essential.…”