Photocatalytic reduction of CO2 on MgO/TiO2 nanotube films

- MgO/TiO2 nanotubes network films showed an excellent activity for CO2 photoreduction.
- MgO played an essential role to keep the nanotubular structure of TiO2 nanotubes.
- MgO has strong adsorption of CO2 to facilitate the photoreduction.
- The formation rate of CH4 reached 100.22 ppm/h cm2 after loading of Pt nanoparticles.

A facile development of highly efficient MgO/TiO2 nanotubes network (MgO/TNTs) films is described. These MgO/TNTs films have a unique one-dimensional (1D) network nanotubular structure, and the different contents of MgO existed as amorphous thin layers located on the surfaces of TiO2 nanotubes. They exhibited excellent photoreduction efficiency of CO2 to methane compared with the bare TiO2 film. MgO plays a critical role in CO2 methanation, because it has the strong adsorption ability of CO2 and initiates the reaction by binding a CO2 molecule, forming a magnesium carbonate species on the surface. For further improve the photocatalytic activity, Pt nanoparticles were loaded on MgO/TNTs films by the photo-reduction method. It was found that the loading of Pt notably improved the transformation efficiency of CO2 to methane, and the highest evolution rate of methane reached 100.22 ppm/h cm2. The fast electron-transfer rate in MgO/TNTs film and the efficient electron-hole separation by the Pt nanoparticals were the main reasons for the enhancement of the photoreduction activity. The synergy effect of Pt nanoparticles and MgO in the nanocomposites played an important role in CO2 photoreduction.