•Black TiO2were prepared by one-step aluminothermic reduction.•Only the oxygen partial pressure at micro-region of TiO2-NTAs surface was changed.•Ti3+ is induced by oxygen vacancies in experiment but not additional intercalation.•Black TiO2 shows efficient photocatalytic CO2 reduction activity (185.39 μmol g−1 h−1). In this work, black titania nanotube arrays (B-TiO2NTAs) were prepared by aluminothermic reduction of anodized TiO2-NTAs. It was found that the oxygen partial pressure atmicro-region of TiO2-NTAs surfacewas critical for the creation of black TiO2 NTAs. The oxygen vacancies in the prepared B-TiO2 NTAs induced new defect energy levels in the band gap of TiO2, which reduced the band gap and broadened their visible light absorption. Furthermore, the oxygen vacancies could also act as the catalytic sites and accelerate surface reactions for the photocatalytic reduction of CO2 to CO, which also was proved by isotope experiment. Especially, B-TiO2 NTAs annealed at 600℃ showed an excellent photocatalytic CO2 reduction to CO performance with the yield of 185.39 μmol g−1 h-1 under visible light illumination because the oxygen vacancy self-doping largely enhanced three key factors in this process, including photoinduced charge generation, charge separation and transportation and interfacial reaction. This facile and versatile method could be potentially used for large scale production of colored TiO2 with a high photocatalytic CO2 reduction capability in the visible light illumination.