Capturing Solar Energy for Cathodic Protection of Metals: The Life of Photoexcited Charge Carriers

Abstract

Solar energy conversion technologies, such as photovoltaics, photocatalysis, and photoelectrolysis, have been intensively investigated for decades as they hold great promise for a sustainable human society. Photoelectrochemical cathodic protection (PECCP), which aims to offer cathodic protection to metals with the assistance of solar irradiation via solar–electric–chemical conversion processes, however, has been largely overlooked by the solar conversion research community. The relatively limited number of relevant works are heavily material‐oriented, in which semiconducting materials that are often employed in photocatalysis and photoelectrocatalysis have been simply introduced to PECCP systems. Moreover, almost all previous review articles on PECCP only focus on the modulation of the photoanode materials. Herein, a review that aims to shed light on the very basics of PECCP systems, for instance, by presenting the complete life of photogenerated charge carriers is presented. The fundamental reaction mechanism, performance evaluation indexes, and recent advances in photoanode design are systematically explained. Finally, some of the key future development directions of PECCP, including photoanode surface/interface engineering, dealing with the challenge of intermittent solar irradiation and integrating other technologies, as well as the need for standardization are discussed.