Hierarchical P-doped TiO2 nanotubes array@Ti plate: Towards advanced CO2 photocatalytic reduction catalysts

Abstract In order to narrow band gaps of semiconductor oxides and extend their working spectra scope, doping non-metal elements with oxides has been an effective strategy. While, doped non-metal elements also bring new charge-carrier trapping and recombination centers, which correspondingly result in the quantum efficiency losses caused by the charge pair recombination. Fortunately, it is demonstrated that the interface of oxide-metal has the abilities to effectively inhibit the recombination of the electron-hole pairs due to the fact that the charge pairs can be spatially separated and the electrons are transported to the surface active sites rapidly. Herein, as a proof-of-concept experiment, P-doped TiO 2 nanotube array@Ti plate (P-TiO 2 NT@Ti plate) hierarchical photocatalysts have been obtained via facile electrochemical anodic oxidation and pyrolytic phosphating approaches. Impressively, obtained P-TiO 2 NT@Ti plate photocatalysts show reduced band gaps (3.02–3.16 eV), high activities and excellent selectivity in the photocatalytic reduction of CO 2 to CH 3 OH (the maximum CH 3 OH yield is 860.4 μmol g −1 cat . for 3.0 h under visible-light irradiation) as a result of the improved electron-hole pair separation rate on the oxide-metal interface, as well as high light harvesting effects derived from the hierarchical nanotube structure.