Dependence of photoelectrochemical water splitting for oriented-SnO2 on Carrier behaviors: Concentration, depletion and transportation

Abstract

An attempt was distinctively made to explore a relationship between photoelectrochemical water splitting (PEC-WS) and fundamental carrier behaviors including carrier concentration, depletion and transportation. The oriented-SnO2 films with miscellaneous electrical characteristics were obtained by magnetron sputtering in combination with joint regulation of oxygen and fluorine. The micro-structure, morphology, electrical characteristics and PEC-WS performance were analyzed by X-Ray Diffractometer, Raman Spectrometer, Photoluminescence Spectrometer, Atomic Force Microscopy, Transmission Electron Microscopy, and Hall Effect Apparatus and Electrochemical Testing System, respectively. The results showed that oxygen vacancy not only served as a source for increasing carrier concentration but also a site for separating photogenerated electrons and holes to promote their smooth transportation, compared with fluorine atom negatively acting as a scattering center. Heavy electron depletion together with high electron concentration from oxygen vacancies is beneficial to photocatalysis process, and PEC-WS performance of SnO2 film reaches a maximum as carrier concentration is about 1019 /cm3. Likewise, this kind of carrier behaviors makes (101)-oriented film present higher water splitting efficiency than (110)-oriented films.