High solar-to-hydrogen efficiency in Z-scheme AlN/GaO heterojunctions for visible light water splitting

Abstract

Hydrogen production from solar energy is an important means to solve the problems of fossil fuel consumption and environmental pollution, and the efficiency of hydrogen production from solar energy is an important indicator. Photocatalytic water decomposition technology driven by solar energy is an ideal way to create clean energy. In this paper, a new Z-scheme AlN/GaO van der Waals heterojunction is proposed. Through first-principles calculations, we have systematically studied the electronic properties and photocatalytic hydrogen production performance of the AlN/GaO heterostructure. The calculation results show that the lattice mismatch rate of the AlN/GaO heterojunction is only 0.48%. At the same time, it not only performs well in terms of thermodynamics, kinetics and mechanical stability, but also has an appropriate band gap of 1.45 eV with an electron mobility of up to 2753.48 cm² V⁻¹ s⁻¹. Under light irradiation, the transfer of internal photogenerated carriers forms a built-in electric field from AlN to GaO, which forms a typical Z-scheme, and leads to the hydrogen evolution reaction on AlN with strong reduction ability. It is worth noting that the AlN/GaO heterojunction shows a high absorption coefficient in the visible light absorption range and has an excellent solar-to-hydrogen efficiency of 60.1%. These advantages demonstrate that the AlN/GaO heterojunction, as a promising photocatalyst, has significant application potential and offers a novel approach to address the energy crisis and environmental pollution challenges.