Recent Advances in Noncontact External-Field-Assisted Photocatalysis: From Fundamentals to Applications

The effective separation of photogenerated carriers plays a vital role in photocatalytic reactions. In addition to the intrinsic driving force of photocatalysis, an external field generating an enhancement effect can provide extra energy to the photocatalytic system, acting as an additional impetus to separate photogenerated charges and thus improving the overall catalytic efficiency. Under the favorable noncontact conditions, exploring the effect of the external field, different from pure photocatalysis or photoelectrocatalysis, could widen the applications of photocatalysis technology. In this review, four typical noncontact external fields (i.e., thermal, magnetic, microwave, and ultrasonic fields) and their coupling effects on photocatalysis are summarized. Specifically, the review focuses on the mechanism and characteristics of each external field's synergistic effect and their coupling effects on the performance of the catalytic system. The charge separation driving forces provided by the noncontact external field and the traditional one are distinguished and defined for the first time. The challenges and future prospects of noncontact external-field-driven photocatalysis are discussed. We hope that this review will provide a reference for the research and development of external-field-assisted photocatalysis and give insights for the in-depth study of external-field-coupling-enhanced photocatalysis toward improvement of the catalytic efficiency.