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

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_δ co-modified TiO₂ enables direct and selective methane oxidation into liquid oxygenates in the presence of O₂ and H₂. Due to the extra ROS production from the in situ formed H₂O₂, a highly improved yield rate of 5014 µmol g^-1 h^-1 for liquid oxygenates with a selectivity of 89.3% is achieved over the optimized Pd_0.5V_0.2-TiO₂ catalyst at ambient temperature, which is much better than those (2682 µmol g^-1 h^-1, 77.8%) without H₂. Detailed investigations also demonstrate the synergistic effect between Pd and VO_δ species for enhancing the charge carrier separation and transfer, as well as improving the catalytic activity for O₂ reduction and H₂O₂ production.