Optimization of NH2-UiO-66/TiO2/Au composites for enhanced gas-phase CO2 photocatalytic reduction into CH4

Here we report on the optimization of NH2-UiO-66/TiO2/Au (ca. 1.5 wt%) composite photocatalysts applied to gas phase CO2 photocatalytic reduction in presence of water as reducing agent by varying NH2-UiO-66/TiO2 ratio and pH during synthesis. It is shown that 10 wt% NH2-UiO-66/TiO2/Au (at pH=7) composite leads to the best cumulated CH4 production rate of 136 mu mol/gcatalyst with 70% electronic selectivity over 5 h of continuous test. This composite exhibits the best compromise between MOF surface area and thus CO2 adsorption sites, visible light photons absorption capacity and a large interface contact area, which ensured preferable metal(Zr)-to-metal(Ti) charge carrier. Au deposition by impregnation/chemical reduction in also required to perform CO2 photoreduction, and may presumably act as electron traps, co-catalyst or surface plasmon resonator.

Automated summary

Here, we optimized NH2-UiO-66/TiO2/Au (ca. 1.5 wt%) composite photocatalysts for gas phase CO2 photocatalytic reduction with water as reducing agent by adjusting NH2-UiO-66/TiO2 ratio and pH during synthesis. It was found that the 10 wt% NH2-UiO-66/TiO2/Au (at pH=7) composite showed the highest cumulated CH4 production rate of 136 mu mol/gcatalyst with 70% electronic selectivity over a 5-hour continuous test. This composite achieved the best compromise between MOF surface area, CO2 adsorption sites, visible light absorption capacity, and a large interface contact area, which facilitated efficient charge carrier transfer from metal(Zr) to metal(Ti). Au deposition by impregnation/chemical reduction was necessary for CO2 photoreduction and may serve as electron traps, co-catalyst, or surface plasmon resonator.