Boosting Reactive Oxygen Species Formation Over Pd and VO Co-Modified TiO₂ for Methane Oxidation into Valuable Oxygenates

Direct photocatalytic methane oxidation into value-added products provides a promising strategy for methane utilization. However, the inefficient generation of reactive oxygen species (ROS) partly limits the activation of CH4. Herein, it is reported that Pd and VO delta co-modified TiO2 enables direct and selective methane oxidation into liquid oxygenates in the presence of O-2 and H-2. Due to the extra ROS production from the in situ formed H2O2, a highly improved yield rate of 5014 mu mol g(-1) h(-1) for liquid oxygenates with a selectivity of 89.3% is achieved over the optimized Pd0.5V0.2-TiO2 catalyst at ambient temperature, which is much better than those (2682 mu mol g(-1) h(-1), 77.8%) without H-2. Detailed investigations also demonstrate the synergistic effect between Pd and VO delta species for enhancing the charge carrier separation and transfer, as well as improving the catalytic activity for O-2 reduction and H2O2 production.