On the Origin of Enhanced Photocatalytic Activity of Copper-Modified Titania in the Oxidative Reaction Systems

Modification of titania with copper is a promising way to enhance the photocatalytic performance of TiO2. The enhancement means the significant retardation of charge carriers' recombination ratio and the introduction of visible light activity. This review focuses on two main ways of performance enhancement by copper species-i.e., originated from plasmonic properties of zero-valent copper (plasmonic photocatalysis) and heterojunctions between semiconductors (titania and copper oxides). The photocatalytic performance of copper-modified titania is discussed for oxidative reaction systems due to their importance for prospective applications in environmental purification. The review consists of the correlation between copper species and corresponding variants of photocatalytic mechanisms including novel systems of cascade heterojunctions. The problem of stability of copper species on titania, and the methods of its improvement are also discussed as important factors for future applications. As a new trend in the preparation of copper-modified titania photocatalyst, the role of particle morphology (faceted particles, core-shell structures) is also described. Finally, in the conclusion section, perspectives, challenges and recommendations for future research on copper-modified titania are formulated.