TiO2-based Pd/Fe bimetallic modification for the efficient photothermal catalytic degradation of toluene: The synergistic effect of ∙O2– and ∙OH species

The construction of photothermal catalysts to provide advanced oxidation ability and stability is a great challenge for eliminating volatile organic compounds (VOCs) during the photothermal catalytic process. Herein, a bimetallic modification method was proposed to synthesize Pd/Fe-TiO2. Under ultraviolet–visible (UV–Vis) light irradiation with the intensity of 610 mW/cm2, the optimal 0.7 wt% Pd/0.4 wt% Fe-TiO2 catalyst of which surface was detected at the temperature of 165 °C can achieve a toluene conversion of 94 % and a CO2 yield of 87 %, respectively. Based on the results of in-situ DRIFTS, quasi-situ EPR, XPS, and O2-TPD tests, it was found that two distinct types of Pd and Fe active sites not only generated reactive oxygen species (ROS) but also adsorbed toluene and intermediate species, which promoted the degradation of toluene. It is proposed that there be an electron transfer behavior between Fe and Pd nanoparticles, resulting in a synergistic interaction of the two metals. This study shows that creating bimetallic modification catalysts is an efficient method for eliminating VOCs through photothermal catalysis.