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

Elemental doping and introduction of vacancies are two effective strategies to manipulate the energy band structure and surface reaction dynamics for improved performance of photoelectrochemical (PEC) water splitting. Herein, we report the facile hydrothermal synthesis of Zn10In16S34 atomically thin nanosheet arrays on fluorine-doped tin oxide glass (FTO) substrates. Through controlling the heat-treatment condition in the air, we can simultaneously introduce O-doping and Zn, S vacancies in Zn10In16S34 nanosheets with adjusted phase, morphology, chemical compositions, and energy level distribution. Furthermore, the surface defects states are passivated by depositing ultrathin Al2O3 film by atomic layer deposition technology. The results show that the performance of Zn10In16S34 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 photo-excited electron-hole pairs separation, decreased surface transfer impedance, prolonged carrier lifetime, and reduced overpotential of oxygen evolution reaction.