Plasma electrolytic oxidation (PEO) layers grown on metals and alloys as supported photocatalysts

Plasma electrolytic oxidation (PEO) is a remarkable electrochemical approach that has been extensively researched to develop adherent conversion oxide layers on metals and alloys. These oxide layers, developed on firm conducting support, have been notably investigated for their photocatalytic applications. The TiO₂ layers developed on titanium and its alloys have been extensively studied. The PEO of aluminum, magnesium, zinc, niobium, zirconium, tantalum, and steel have also been explored. The catalytic activity of the developed oxide layer can be boosted by various approaches, such as doping and heterojunction formation via in-situ integration or post-impregnation of the active components. The present review comprehensively accounts for PEO-derived photocatalysts in different applications, providing a reliable source of information for researchers in the field. The sections are classified based on the base substrate metal used for PEO. The role of PEO parameters in deciding the developed layers' photocatalytic activity is discussed. Doping/heterojunctions with nonmetals, transition/post-transition metals, precious metals, rare earths, nanocarbons, and others are detailed.