Photoelectrochemical study of Ti3+ self-doped Titania nanotubes arrays: A comparative study between chemical and electrochemical reduction

Abstract

Water splitting through the photoelectrochemical process is a solid strategy to produce clean hydrogen for which TiO2 isconsideredthe most potential photoanode due to its unique properties. However, its wideband gap and high charge carrier recombination rate limit its solar-to-hydrogen conversion efficiency. Here in we report the fabrication of the Ti3+ self-doped TiO2 nanotube samples prepared through electrochemical and Chemical (NaBH4 treatment) reduction. Structural and morphological analysis carried through XRD and FESEM respectively confirmed the formation of TiO2 nanotube arrays. XPS spectra were used to affirm the presence of Ti3+ states in the reduced sample. The absorption edge observed in the 430–500 nm range validated the reduction of the band gap to the visible range in Ti3+ self-doped samples. Photoelectrochemical results of both the reduced samples evince their potential applicability as a photoanode for hydrogen generation through PEC water splitting. EIS and absorbance spectra reveal that larger charge density, faster electron-hole separation, and better visible light absorption may be thefactors that contribute to reducing TiO2′s superior photoelectrochemical performance. However, a comparative study shows better results for electrochemically reduced samples, suggesting it is an effective technique than chemical reduction.