Characterization methods of S-scheme photocatalyst

Photocatalysis is considered as an efficient approach for alleviating energy crises and environmental pollution. However, the performance of single photocatalysts is unsatisfactory due to the rapid recombination of photogenerated electrons and holes. Thus, the development of heterojunction photocatalysts is necessary. The emerging S-scheme heterojunction photocatalyst has shown its superiority due to spatial separation and maximized redox abilities of photogenerated electrons and holes. Therefore, numerous researchers have plunged into the design and synthesis of S-scheme heterojunction photocatalysts. In this regard, the development of characterization techniques is imperative to confirm the electron transfer mechanism in S-scheme heterojunctions. Against this backdrop, in this chapter, we summarize the advanced characterization techniques that are used to analyze the charge transfer mechanism in S-scheme heterojunction. For each characterization technique, the fundamental principle is illustrated first. Afterward, the representative examples are presented to demonstrate their applications. This chapter aims to help the researchers in selecting suitable techniques for testifying the S-scheme heterojunction and inspire the development of new S-scheme heterojunction photocatalysts with superior performance.