Investigating the Role of Oxygen Vacancies and Lattice Strain Defects on the Enhanced Photoelectrochemical Property of Alkali Metal (Li, Na, and K) Doped ZnO Nanorod Photoanodes

This work demonstrates the significance of defect engineering in tuning the visible-light-driven photoelectrochemical property of alkali metal (Li, Na, and K) doped ZnO nanorods. The large concentration of oxygen vacancies introduced into the sub-bandgap, because of alkali metal doping, serve as the light-absorbing donor sites and also photoelectron recombination centers, resulting in the enhanced photocurrent and hole separation in the valance band. The lattice strain developed in the nanorods, owing to doping, contributes to the easy electron transportation and mobility. Defect engineering also tunes the electronic structure of photoanodes, resulting in bandgap modification and band edge engineering, boosting charge-carrier migration and reduced electron-hole pair recombination for enhanced oxygen evolution.