Enhanced Photocatalytic Reduction of CO2 on Rutile TiO2/MgAl Layered Double Oxides with H2O Under Ambient Temperature

Photocatalytic reduction of CO2 with H2O is a fascinating approach to convert CO2 into available fuels using solar energy as driven force. However, it still suffers from low efficiency owing to the instinct stability of CO2. In this work, a hybrid photocatalyst of rutile TiO2 nanorods supported on MgAl layered double oxides (TiO2/MgAl-LDO) were designed and facilely fabricated via an in situ growth followed by a high temperature calcination process. The resulted TiO2/MgAl-LDO demonstrated significantly enhanced photocatalytic reduction of CO2 with the optimal CO and CH4 evolution of 0.65 and 1.60 mu mol in 8 h reaction under ambient temperature, which is ca. 4.6 and 48 times that of TiO2 respectively. X-ray photoelectron spectroscopy revealed a strong electron interaction between TiO2 and MgAl-LDO, as well as electrochemical characterization showed enhanced photocurrent, suggesting a promoted charge separation in photocatalytic process. CO2-temperature-programmed desorption (CO2-TPD) unveiled the relatively active bicarbonate, bidentate carbonate and monodentate carbonate species were formed on MgAl-LDO, which could boost the CO2 reduction half-reaction. Meanwhile, NH3-TPD revealed acidic sites existed in TiO2/MgAl-LDO, which could act as active sites for H2O adsorption and activation and thus promote the H2O oxidation half-reaction. The strategy of simultaneous promotion on the reduction and the oxidation half-reactions will open a new vane to fabricate highly efficient catalysts toward photocatalytic reduction of CO2 with H2O. [GRAPHICS] .