上海科技大学知识管理系统

The built-in potential in the space charge layer dominates migration of charge carriers in a traditional photoelectrode model. In this work, through particle engineering and surface reconstruction, a Rh-doped rutile TiO2 (Rh-TiO2) photoelectrode is fabricated, in which the Rh concentration is decreased gradiently in TiO2 particle directed from conductive substrate to solution. Since the Rh dopants involve intragap states above the valence band of TiO2, it shapes a built-in potential that orients the migration of photoexcited holes toward substrate and repels the electrons to solution side, which change the Rh-TiO2 electrode from photoanode to photocathode. Comparison of intensity modulated photocurrent spectroscopy (IMPS) results using ultraviolet and visible light across a wide potential window unveils the different roles of dopants in charge dynamics. The operando chemical status of Rh is further verified by spectroelectrochemical characterization. The present strategy of directional doping not only is conducive to improving electron-hole separation but also provides a new approach to unleash the potential of a semiconductor as both photoanode and photocathode. © 2024 American Chemical Society.