Arsenene/Ti₂CO₂ Heterojunction as a Promising Z‐Scheme Photocatalyst for Overall Water Splitting

Abstract In order to address imminent energy and environmental challenges, photocatalytic water splitting emerges as a promising way for harnessing solar radiation to generate clean chemical energy. 2D arsenene (β‐As) has notable catalytic activity in hydrogen production. Based on first principles calculations and non‐adiabatic molecular dynamics (NAMD) simulations, the β‐As/Ti₂CO₂ heterojunction is predicted to be a promising Z‐scheme photocatalyst for overall solar water splitting. It has a desirable energy band structure with the valence band maximum of Ti₂CO₂ and the conduction band minimum of β‐As well below and above the redox potentials of H₂O. Both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) can proceed spontaneously under light irradiation. NAMD simulations confirm that it is a Z‐scheme photocatalyst with fast electron–hole combination dynamics. Instead of by intrinsic electric field, such a fast electron–hole combination is driven by a large nonadiabatic coupling. The heterojunction exhibits strong optical absorption in the visible and ultraviolet regions. The estimated solar‐to‐hydrogen (STH) efficiency limit of β‐As/Ti₂CO₂ reaches 32%, which is the highest among all β‐As based junctions reported in the literature. These results suggest that β‐As/Ti₂CO₂ is a promising photocatalyst for achieving overall water splitting.