• • Jidong Li，Han Sheng，Yuyang Long，Yunfei Zhang，Chenwei Fu

• Xuemei Li，Wanlin Guo，Jun Yin*

ACS Appl. Mater. Interfaces 2024, 16, 31, 41653–41658

Abstract

Moving boundaries of electrical double layers have shown promising capability in driving directional electron flows in solids, leading to a range of hydrovoltaic effects. The recent discovery of a photohydrovoltaic phenomenon utilizes a moving illumination zone to generate moving boundaries with different properties at the solid–water interface, referred to as the kinetic photovoltaic effect. Here, oxygen was found to act as a chemical switch to turn on and off the kinetic photovoltaic effect. Introducing oxygen would rapidly diminish the kinetic photovoltage in p-Si. On the contrary, degassing oxygen leads to a gradual recovery, whose rate can be facilely speeded up by more than one order through electrostatic gating. Mechanistic investigations of the oxygen switch behavior uncovered a dependence of surface band bending intensity of silicon on oxygen adsorption, which highlights the role of gas molecules, often overlooked, in applications based on semiconductor–liquid interfaces, such as photoelectrochemistry.

https://doi.org/10.1021/acsami.4c06131