Theoretical computational study of the effect of point defects and equivalent elemental doping on the photoelectrocatalytic properties of ZnO monolayers (0 0 1)

Under vacuum conditions, the preparation of ZnO systems via atmospheric pressure plasma often results in the inevitable presence of extrinsic H interstitials. Previous studies have neglected the coexistence of oxygen vacancies and H interstitials, and the manipulation of point defects in physical experiments is challenging. This study utilizes the first-principles GGA + U approach to systematically analyze how the co-existence of oxygen vacancies and hydrogen interstitials affects photocatalytic properties. The investigation focuses on two series of (0 0 1)-oriented monolayers: Zn₃₆TO₃₄ and Zn₃₆H_iTO₃₄, where T represents chalcogen elements (S, Se, Te). Among all systems, the Zn₃₆H_iTeO₃ (0 0 1) monolayer demonstrates optimal performance. This material exhibits enhanced stability under zinc-rich conditions, along with favorable formation energy and high catalytic activity. Its superior characteristics include extended light absorption range, appropriate work function, prolonged carrier lifetime, and exceptional photocatalytic reduction capacity. Notably, the Zn₃₆H_iTeO₃ (0 0 1) system displays dual functional advantages: relatively low internal voltage and excellent electrocatalytic performance. These findings establish fundamental theoretical principles for designing advanced ZnO-based materials in both photocatalytic and electrocatalytic applications.