Active Sites in Single-Layer BiOX (X = Cl, Br, and I) Catalysts for the Hydrogen Evolution Reaction.

Although few-layer bismuth oxyhalides (BiOX, X = Cl, Br, and I) have been shown to be appropriate for photocatalytic hydrogen production, the hydrogen evolution reaction (HER) activity of BiOX is unrevealed. Herein, the origins of catalytic activity on single-layer BiOX are investigated by using the density functional theory. The grand potential calculations show that the Bi- and BiO-terminations of single-layer BiOX are stable in O-poor and O-rich environments, respectively.