3D-carbon dots decorated black TiO2 nanotube Array@Ti foam with enhanced photothermal and photocatalytic activities

Abstract Nanostructured titanium oxide semidconductors are considered as potential materials for photothermal and photocatalytic applications. However, investigation on usage of titanium oxide nanotube array lay behind other titanium oxide nanomaterials. In order to change this uneven situation, we reported herein that carbon dots decorated black TiO 2 nanotube array@Ti foam (CDs/Black TNA@Ti) can work as highly efficient device for solar-driven water evaporation and pollutant degradation. Initially, TiO 2 nanotube array@Ti foam (TNA@Ti) was prepared through anodization of Ti foam. Through subsequent hydrogenation treatment and carbon dots decoration, CDs/Black TNA@Ti was finally achieved. It was found that CDs/Black TNA@Ti demonstrated three characters including excellent solar light absorption ability, wettability and hierarchical porous structure. For these advantages, photothermal property of TNA@Ti was stepwise improved. In solar-driven water evaporation experiment, water evaporation rate and solar thermal conversion efficiency attained 1.762 kg m −2  h −1 and 55.3% respectively for CDs/Black TNA@Ti, which are higher than previous reports on titanium oxide nanotube array. CDs/Black TNA@Ti also exhibited higher photocatalytic property than other samples without hydrogenation and/or carbon dots decoration. The CDs/Black TNA@Ti is promising for practical applications in solar-driven water evaporation and purification.