Insights into the Effect of Reactive Oxygen Species Regulation on Photocatalytic Performance via Construction of a Metal-Semiconductor Heterojunction

Abstract

Reactive oxygen species (ROS), as primary intermediates formed during photocatalytic reactions, are critical for a photocatalyst to realize high activity. The major objective of this study was to investigate the regulation of ROS involved in the photocatalytic degradation process via constructing a typical metal-semiconductor hybrid heterojunction using Ag nanoparticles/anatase TiO2 as an example. Based on radical capturing, electron paramagnetic resonance, and electron spin resonance experiments, an increase in the available ROS can be achieved in the Ag/TiO2 heterojunction due to the fast separation of photogenerated carriers. In addition, due to the change in the electron transfer pathway, superoxide radicals (·O−2) are the dominant reactive species responsible for dye degradation using Ag/TiO2 rather than hydroxyl radicals (·OH) as the main free radicals in pristine TiO2. This study offers fresh insight into the regulation of ROS in photodegradation via the construction of a Ag/TiO2 heterojunction.