Rational engineering of semiconductor-based photoanodes for photoelectrochemical cathodic protection

Photoelectrochemical (PEC) cathodic protection based on semiconductor photoanodes, by combining solar energy utilization and metal anticorrosion, provides a promising platform for developing an environmentally friendly metal protection technology. In this context, semiconductors (e.g., TiO2, ZnO, SrTiO3, BiVO4, and g-C3N4), with merits of suitable band structure, good chemical stability, and low cost, have attracted extensive attention among the investigated photoanode candidates. However, the poor optical absorption properties and the high photogenerated charge recombination rate severely limit their photocathodic protection performances. In order to break these limitations, different modification strategies for these photoanodes have been developed toward the significant enhancement in PEC cathodic protection properties. In this Review, the rational engineering of semiconductor-based photoanodes, including nanostructure design, elemental doping, defect engineering, and heterostructure construction, has been overviewed to introduce the recent advances for PEC cathodic protection. This Review aims to provide fundamental references and principles for the design and fabrication of highly efficient semiconductor photoanodes for PEC cathodic protection of metals.