TiO2 nanotube arrays decorated with plasmonic Cu, CuO nanoparticles, and eosin Y dye as efficient photoanode for water splitting

Photoelectrochemical (PEC) splitting of water over a semiconductor is an ideal and clean way to produce hydrogen by using solar energy. Herein, a photoanode of TiO2 nanotube arrays (TNTA) was decorated with environment-friendly Cu-based nanomaterials through a two-step electrochemical process, followed by sensitization with eosin Y dye, for PEC water splitting. The confirmations of Cu and CuO on the surface of TNTA were recorded by XRD combined with XPS techniques. The obtained Cu-CuO/TNTA and Eosin Y/Cu-CuO/TNTA electrodes exhibit good light absorption abilities in the range of 380-600 nm, and the adsorption of Eosin Y is enhanced. Based on the analysis of the charge transfer resistance and energy levels of Cu, CuO, TiO2, and eosin Y, it can be found that the deposition of Cu-CuO and eosin Y on TNTA can greatly accelerate the interface charge transfer, resulting in enhanced PEC performances. Moreover, the plasmonic Cu and eosin Y can help to harvest more visible light and further improve the photocurrent density.