Multiple crystal phases of intermetallic tungsten borides and phase-dependent electrocatalytic property for hydrogen evolution.

Four stoichiometric W-B intermetallic phases, including W2B, WB, WB2 and WB3, are synthesized, and their hydrogen-evolution electrocatalytic properties and electronic structures are investigated comparatively. The electrocatalytic activity for the hydrogen evolution reaction is found to first increase from W2B to WB2 and then decrease; and this activity trend can be rationalized based on their different degrees of hybridization between d orbitals of W and sp orbitals of B.