Electric-/magnetic-field-assisted photocatalysis: Mechanisms and design strategies

Photocatalysis as a promising approach for solar energy conversion has attracted enormous attention in recent decades with various chemical reactions involved. Many strategies and techniques have been developed to improve the efficiency of photocatalytic systems. Their practical applications, however, are rather limited, mainly due to their poor performance. The application of external electric/magnetic fields emerges as an effective strategy to enhance photocatalytic performance, which is both tunable and compatible with the existing photocatalytic systems. Yet there is a lack of systematic comparisons and in-depth analysis of the impacts and mechanisms of the external field effects with respect to their intensity, frequency, direction, etc. More importantly, the recent development of electric-/magnetic-field-assisted photocatalysis also urges the design of novel catalyst systems that provide not only an effective response but also extra enhancement. Herein, recent advances in the electric-/magnetic-field-assisted photocatalytic enhancements have been systematically reviewed. The effects of static electric and magnetic fields as well as microwaves as typical electromagnetic fields on the three fundamental photocatalytic steps (i.e., light absorption, charge carrier separation, and surface reactions) have been illustrated with the underlying mechanisms revealed by novel characterization techniques. Especially, this review focuses on the rational design of catalytic systems to incorporate catalyst-support interaction, aiming to generate local effects to enhance the function of external fields. Strategies for the further utilization of external fields in photocatalysis and broader energy technologies have been proposed, and potential challenges for the future study have also been discussed.