Hydrogen generation via water splitting with hexagonal silicon monolayers as (photo)catalysts

Abstract

Here, we explore the possibility of using pristine hexagonal silicon (hex‑Si) monolayers as (photo)catalysts for water splitting. We found that pristine hex‑Si monolayers show promise as H2O activation site, promoting oxygen evolution reaction (OER), and energetically favorable O2 production in both acidic and alkaline media. However, hydrogen evolution reaction (HER) and OER on this surface do require a substantial overpotential due to the weak bond between H2O and the pristine hex‑Si monolayer, strong H and OH adsorption on the hex‑Si surface, and the energy needed for OOH binding in both acidic and alkaline conditions. Understanding these findings aids in developing hex‑Si-based (photo)catalysts for future water splitting reactions.