Cu₂O/TiO₂ p–n heterojunction photoelectrodes were prepared by depositing different amounts of p-type Cu₂O nanoparticles on n-type TiO₂ nanotube arrays (i.e., forming Cu₂O/TiO₂ composite nanotubes) via an ultrasonication-assisted sequential chemical bath deposition. The success of deposition of Cu₂O nanoparticles was corroborated by structural and composition characterizations. The enhanced absorption in the visible light region was observed in Cu₂O/TiO₂ composite nanotubes. The largely improved separation of photogenerated electrons and holes was revealed by photocurrent measurements. Consequently, Cu₂O/TiO₂ heterojunction photoelectrodes exhibited a more effective photoconversion capability than TiO₂ nanotubes alone in photoelectrochemical measurements. Furthermore, Cu₂O/TiO₂ composite photoelectrodes also possessed superior photoelectrocatalytic activity and stability in the degradation of Rhodamine B. Intriguingly, by selecting an appropriate bias potential, a synergistic effect between electricity and visible light irradiation can be achieved.

This Review highlights the recent developments pertaining to pure and modified TiO₂ nanotube arrays for photocatalysis.

Plasmonics has remained a prominent and growing field over the past several decades. The coupling of various chemical and photo phenomenon has sparked considerable interest in plasmon‐mediated photocatalysis. Given plasmonic photocatalysis has only been developed for a relatively short period, considerable progress has been made in improving the absorption across the full solar spectrum and the efficiency of photo‐generated charge carrier separation. With recent advances in fundamental (i.e., mechanisms) and experimental studies (i.e., the influence of size, geometry, surrounding dielectric field, etc.) on plasmon‐mediated photocatalysis, the rational design and synthesis of metal/semiconductor hybrid nanostructure photocatalysts has been realized. This review seeks to highlight the recent impressive developments in plasmon‐mediated photocatalytic mechanisms (i.e., Schottky junction, direct electron transfer, enhanced local electric field, plasmon resonant energy transfer, and scattering and heating effects), summarize a set of factors (i.e., size, geometry, dielectric environment, loading amount and composition of plasmonic metal, and nanostructure and properties of semiconductors) that largely affect plasmonic photocatalysis, and finally conclude with a perspective on future directions within this rich field of research.