CdSe modified TiO₂ nanotube arrays with Ag nanoparticles as electron transfer channel and plasmonic photosensitizer for enhanced photoelectrochemical water splitting

Ag nanoparticles (NPs) and a CdSe nanocrystal were successively deposited on the surface of a TiO₂ nanotube array film (CdSe/Ag/TiO₂ NTs) via microwave assisted chemical reduction and in situ fabrication methods. The nanotubular structure of TiO₂ preserves well after loading Ag and CdSe, as the ternary composite not only exhibits an excellent visible light harvesting ability but also has the smallest charge transfer resistance according to electrochemical impedance measurement. The most positive flat band potential of CdSe/Ag/TiO₂ NTs facilitates charge carrier transfer at the semiconductor-electrolyte interface. Notably, the introduction of Ag nanoparticles forms a unique carrier-transfer-channel in the CdSe/Ag/TiO₂ NTs system, in which the Ag nanoparticles can take advantage of its high carriers transfer rate as a linker. In addition, Ag serving as a surface plasmon resonance source further improves photoelectric catalytic activities of the sample. It is noteworthy that CdSe/Ag/TiO₂ NTs exhibits the desired photoelectrochemical performance with the highest H₂ production rate of 413.99 µmol cm⁻² after 2.5 h irradiation. (paper)