Review—Photoelectrochemical Cathodic Protection in The Dark: A Review of Nanocomposite and Energy-Storing Photoanodes

Semiconductor photoanode-based cathodic protection, prevalently known as photoelectrochemical cathodic protection (PECP) is a potential environmentally benign alternative to the conventionally used sacrificial anode cathodic protection. The unlimited availability of solar energy is the prime attractive factor. A crucial disadvantage of PECP restricting its widespread practical application is its incapability to extend the cathodic protection in the absence of sunlight. Semiconductor nanocomposites of TiO2 with energy-storing supercapacitor materials is the most widely investigated approach to overcome the drawback. Here, we attempt to bring together all the reported information on semiconductor photoanodes with energy-storing attributes in PECP application. Nanocomposites of TiO2 with pseudocapacitive semiconductors are highlighted. Corresponding works published on PECP by surface coatings (analogous to sacrificial coatings) are also discussed. Future scopes of R & D presented.