TiO2-UiO-66-NH2 nanocomposites as efficient photocatalysts for the oxidation of VOCs

TiO2-UiO-66-NH2 nanocomposites with different mass ratios were successfully prepared by a simple solvent evaporation method for photocatalytic oxidation of toluene and acetaldehyde under UV light condition. The experimental results revealed that the nanocomposites exhibited superior removal efficiency for toluene and acetaldehyde than the pure TiO2, UiO-66-NH2 and other TiO2-based porous materials during a 720 min of long-term evaluation under flowing conditions. The as-prepared 75TiO2-25UN nanocompoites exhibited the highest photocatalytic activity and CO2 selectivity. The conversion of 75TiO2-25UN for toluene and acetaldehyde were 72.7% and 70.74% respectively, which was about 9.7 and 10.5 times higher than that of UiO-66-NH2, respectively. In addition, the CO2 production of 75TiO2-25UN for toluene and acetaldehyde were 21.1 and 14.3 times higher than that of pure UiO-66-NH2, respectively. N2 adsorption-desorption and SEM results revealed that high surface area could enhance the dispersion of TiO2 and efficient contact to the VOCs. Photoelectrochemical properties indicated that photoinduced carriers can be efficiently separated and transferred via the interface of two components. The outstanding deactivation resistance was achieved over 75TiO2-25UN sample due to the efficient charge transfer and oxygen-rich condition. The possible mechanism of VOCs oxidation was proposed based on radical scavenger experiments, which proved that O2− and h+ are the main active species. This work clearly demonstrated that MOF-based composite can be used as efficient photocatalysts for the application of VOCs oxidation.