Nonstoichiometric In2O3 nanorods/black Ti–Ni–O nanotubes heterojunction photoanode for high-efficiency photoelectrochemical water splitting

• The black Ti-Ni-O nanotubes photoanode was fabricated through Sn reduction.
• In2O3 nanorods were fabricated by electrochemical deposition method.
• The heterojunction photoanode exhibited high performance photocatalysis property.
• Nonstoichiometric defects can enhance the photocatalytic performance effectively.

Here we report photocatalytic application of heterojunction based on In2O3 nanorods decorated black Ti–Ni–O nanotubes. Black Ti–Ni–O nanotubes were fabricated through tin metal reduction reaction with the as-annealed Ti–Ni–O samples. Structural, morphological and optical properties of the heterostructure were characterized by scanning electron microscopy (SEM), Raman microscopy, X-ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectra techniques. Nonstoichiometric defects caused by oxygen vacancies in both the In2O3 and the Ti–Ni–O oxides could improve both the visible and infrared absorption, and thus effectively enhance the photocatalytic performance. The heterostructure photoanodes could yield a photocurrent density of 5.32 mA/cm2 at 0 V vs. Ag/AgCl in 1 M KOH and a remarkable photoconversion efficiency of 3.18% at −0.52 V vs. Ag/AgCl.