Controlling Water Oxidation Catalysis through Interlayer Arrangements and Vacancies toward Producing Clean Hydrogen

Hydrogen fuel is one of the most promising, renewable, and carbon-free alternatives to contaminating fossil fuels that are being used to date. Producing hydrogen by water splitting may not be efficient in some catalysts mainly due to the high overpotential that exists in forming oxygen, a half-reaction that occurs on the anode where water molecules are being oxidized. One of the best catalysts for the oxygen evolution reaction (OER) with a low overpotential is a unique two-dimensional bilayer system composed of monolayers of defected graphene and Fe-doped β-Ni(OH)2. Here, we display by density functional theory how carbon vacancies and possible mechanical changes including sliding and twisting between layers of graphene//β-NiOOH affect the OER overpotential. Our results show that larger sliding energy between layers at an optimal concentration of carbon vacancies indicates better adhesion and electron transfer between the layers that consequently lowers the OER overpotential. This study contributes to understanding that finding improved two-dimensional catalysts for green hydrogen production could be achieved by designing interfaces with greater bonding and that sliding energy between the layers may serve as a control handle for engineering better catalysts.