Highly visible light responsive metal loaded N/TiO2 nanoparticles for photocatalytic conversion of CO2 into methane

Photocatalytic reduction of carbon dioxide (CO2) into valuable hydrocarbon such as methane (CH4) using water as reducing agent is a good strategy for environment and energy applications. In this study, a facile and simple sol-gel method was employed for the synthesis of metal (Cu and Ag) loaded nanosized N/TiO2 photocatalyst. The prepared photocatalysts were characterized by X-ray diffraction, transmission electron microscopy, BET Surface area analyzer, X-ray photoelectron spectroscopy and UV-vis diffuses reflectance spectroscopy. The photocatalytic conversion of CO2 into methane was carried out under visible light irradiation (λ≥420 nm) by prepared photocatalysts in order to evaluate the photocatalytic efficiency. The results demonstrate that Ag loaded N/TiO2 showed enhanced photocatalytic performance for methane production from CO2 compared to other Cu-N/TiO2, N/TiO2 and TiO2 photocatalysts. The improvement in the photocatalytic activity could be attributed to high specific surface area, extended visible light absorption and suppressed recombination of electron - hole pair due to synergistic effects of silver and nitrogen in the Ag-N/TiO2 photocatalyst. This study demonstrates that Ag-N/TiO2 is a promising photocatalytic material for photocatalytic reduction of CO2 into hydrocarbons under visible light irradiation.