Charge Steering in Heterojunction Photocatalysis: General Principles, Design, Construction, and Challenges.

Steering charge kinetics is a key to optimizing quantum efficiency. Advancing the design of photocatalysts (ranging from single semiconductor to multicomponent semiconductor junctions) that promise improved photocatalytic performance for converting solar to chemical energy, entails mastery of increasingly more complicated processes. Indeed, charge kinetics become more complex as both charge generation and charge consumption may occur simultaneously on different components, generally with charges being transferred from one component to another. Capturing detailed charge dynamics information in each heterojunction would provide numerous significant benefits for applications and has been needed for a long time. Here, the steering of charge kinetics by modulating charge energy states in the design of semiconductor-metal-interface-based heterogeneous photocatalysts is focused. These phenomena can be delineated by separating heterojunctions into classes exhibiting either Schottky/ohmic or plasmonic effects. General principles for the design and construction of heterojunction photocatalysts, including recent advances in the interfacing of semiconductors with graphene, carbon quantum dots, and graphitic carbon nitride are presented. Their limitations and possible future outlook are brought forward to further instruct the field in designing highly efficient photocatalysts.