Facile synthesis of thin black TiO2 − x nanosheets with enhanced lithium-storage capacity and visible light photocatalytic hydrogen production

In combination of a facile and scalable solvothermal method and solid-phase reduction reactions, a novel two-dimensional black TiO2 − x nanosheet (TiO2 − x NS) with high specific surface area of 108 m2 g−1 and nearly total solar spectral absorption capability have been successfully prepared. With careful characterizations, the novel TiO2 − x NS showed enhanced electrochemical performance and visible-light photocatalytic activity than those of their white TiO2 nanosheet (TiO2 NS) precursors. The black TiO2 − x NS electrode delivered a reversible specific capacity of 160 mA h g−1 even after cycling at 0.5 C (1 C = 190 mA h g−1) for 300 times, which was significantly higher than the corresponding white TiO2 NS electrode (104 mA h g−1). Meanwhile, the TiO2 − x NS also exhibited enhanced ability of visible-light photocatalytic hydrogen production than that of the white TiO2 NS. It is expected that making white TiO2 NS into black ones is an effective way to design the photocatalysts with visible light response and the anodes with long lifetime and high rate performance in lithium ion batteries. The novel black TiO2 − x NS could find potential applications in the field of environmental management and energy storage and conversion.