Black Ni-doped TiO2 photoanodes for high-efficiency photoelectrochemical water-splitting

Photocatalysis is a promising solar energy conversion technique. Here we report a simple but efficient way to fabricate black Ni-doped TiO2 photoanodes for photoelectrochemical water-splitting. The black Ni-doped TiO2 photoanodes were fabricated through anodization for nanotube growth and one-step tin metal reduction in argon atmosphere. X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Raman spectra were used to characterize the black Ni-doped TiO2 photoanodes. The black Ni-doped TiO2 photoanodes presented large amounts of Ti3+ and oxygen vacancy, which ensured high capability of absorbing visible and infrared light. The black Ni-doped TiO2 photoanodes exhibited an excellent and stable photocatalytic activity compared to undoped TiO2 photoanode. The maximum photoconversion efficiency of the black Ni-doped TiO2 photoanodes was 2.95% at −0.56 V vs Ag/AgCl, which was almost ten times as high as that of the undoped TiO2 photoanode.