High‐Current‐Density HER Electrocatalysts: Graphene‐like Boron Layer and Tungsten as Key Ingredients in Metal Diborides

Abstract

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Crystallographic facet selective HER catalysis: exemplified in FeP and NiP2 single crystals

“…For the abundant transition metals such as Mn, Fe, Co, Ni, and Mo, an HER catalyst is not a single metal but a binary compound with non-metal elements (P, S, B) which brings strong chemical bonding and resulting chemical resistance. 12,36,37,[47][48][49][50] Moreover, metal atoms arrangement and band structure of the binary material are signicantly different from those for elemental metals. Recent experimental and computational studies of crystals of Mo borides show that selected surfaces exhibit signicantly higher HER activity, such as graphene-like boron-rich surfaces.…”

“…Recent experimental and computational studies of crystals of Mo borides show that selected surfaces exhibit signicantly higher HER activity, such as graphene-like boron-rich surfaces. [47][48][49][50] While borides are known for high chemical inertness, in the eld of transition-metal phosphide HER catalysts, it is commonly assumed that the surface of the catalysts is restructured during the reaction as a result of the applied bias potential and chemical potential of protons in solution. Evidence for this is the observed ex situ surface oxidation aer potential cycling.…”

Hydrogen Evolution on Restructured B-Rich WB: Metastable Surface States and Isolated Active Sites

“…1,2 Among the large family of compounds, borides have been the less studied while perhaps the most intriguing, due to the rich chemistry of boron (both covalent, and delocalized and nondirectional bonds, structural diversity). [3][4][5] A group of transition metal borides, including those of cobalt, 6 nickel, 7 molybdenum, 8 vanadium, 9 and tungsten, 10 has been identified as active electrocatalysts for hydrogen evolution reaction (HER) with a high current density and long-term stability.…”

“…The B 8 islands that formed from restructuring of excess boron could effectively act as sub-nano aerophobic units and prevent the gas accumulation problem. This could also explain the outstanding stability of the borides in long-term and high-current-density electrocatalysis without elaborate nanostructuring 10. 20Figure 8.…”

Effect of Ni Doping on the MoS2 Structure and Its Hydrogen Evolution Activity in Acid and Alkaline Electrolytes

“…As an alternative to the Platinum Group Metals (PGMs) based catalysts, which are nowadays in the list of the Critical Raw Materials (CRMs) [8,9], many types of earth-abundant transition metal-based catalysts are intensively investigated [10,11]: metals; alloys; carbides; nitrides [12]; borides [13,14]; and, above all, transition metals dichalcogenides (TMDCs) [15]. TMDCs are 2D-layered materials that have been extensively studied as HER electrocatalysts.…”