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.