Simultaneous Manipulation of O‐Doping and Metal Vacancy in Atomically Thin Zn₁₀In₁₆S₃₄ Nanosheet Arrays toward Improved Photoelectrochemical Performance

The facile hydrothermal synthesis of Zn₁₀ In₁₆ S₃₄ atomically thin nanosheet arrays on fluorine-doped tin oxide glass (FTO) substrates is presented. Through controlling heat treatment in air, O-doping and Zn, S vacancies were simultaneously introduced in Zn₁₀ In₁₆ S₃₄ nanosheets with adjusted phase, morphology, chemical compositions, and energy level distribution. The surface defect states are passivated by depositing ultrathin Al₂ O₃ film by atomic layer deposition technology. The performance of Zn₁₀ In₁₆ S₃₄ photoanodes is largely improved, with 4.7 times higher current density and reduced onset potential. The experimental results and density functional theory calculations indicate that the enhancement is attributed to the fast photoexcited electron-hole pair separation, decreased surface transfer impedance, prolonged carrier lifetime, and reduced overpotential of oxygen evolution reaction.