Mechanistic understanding on oxygen evolution reaction on γ-Fe OOH(010) under alkaline condition based on DFT computational study

An efficient and economical oxygen evolution reaction(OER)catalyst is critical to the widespread application of solar energy to fuel conversion.Among many potential OER catalysts,the metal oxyhydroxides,especially FeOOH,show promising OER reactivity.In the present work,we performed a DFT+U study of the OER mechanism on theγ‐FeOOH(010)surface.In particular,we established the chemical potential of the OH?and hole pair and included the OH?anion in the reaction pathway,accounting to the alkaline conditions of anodic OER process.We then analyzed the OER pathways on the surface with OH‐,O‐and Fe‐terminations.On the surface with OH‐and O‐terminations,the O2molecule could form from either OH reacting with the surface oxygen species(-OH*and-O*)or the combination of two surface oxygen species.On the Fe‐terminated surface,O2can only form by adsorbing OH on the Fe sites first.The potential‐limiting step of the oxygen evolution with different surface terminations was determined by following the free‐energy change of the elementary steps along each pathway.Our results show that oxygen formation requires recreating the surface Fe sites,and consequently,the condition that favors the partially exposed Fe sites will promote oxygen formation.