AlN/Ti2CO2 van der Waals heterostructure: a direct Z-scheme photocatalyst for efficient photocatalytic water splitting†

Abstract

This study proposes a direct Z-scheme AlN/Ti₂CO₂ van der Waals (VdWs) heterostructure for efficient photocatalytic water splitting. Through first-principles calculations, we systematically investigated the structural stability, electronic properties, carrier dynamics, and photocatalytic performance of the AlN/Ti₂CO₂ van der Waals heterostructure. The electronic structure calculations indicate that the heterostructure has a type-II alignment and exhibits high carrier mobilities. The built-in electric field at the interface facilitates Z-scheme charge transfer, preserving high redox potentials for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The free energy calculation indicates that the AlN/Ti₂CO₂ heterostructure has high activity for overall water splitting. The heterostructure achieves broad visible-light absorption with significantly improved coefficients compared to individual monolayers. Strain engineering can be employed to modulate the bandgap, band edge positions and light absorption, thereby optimizing the photocatalytic water-splitting performance of the heterostructure. These findings highlight the AlN/Ti₂CO₂ heterostructure as a promising, tunable photocatalyst for solar-driven water splitting, offering a framework for designing high-efficiency, low-carbon hydrogen production systems.