Boosting Reactive Oxygen Species Formation Over Pd and VO δ Co-Modified TiO 2 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 CH 4 . Herein, it is reported that Pd and VO δ co-modified TiO 2 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 H 2 O 2 , 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 0.5 V 0.2 -TiO 2 catalyst at ambient temperature, which is much better than those (2682 µmol g -1  h -1 , 77.8%) without H 2 . 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 O 2 reduction and H 2 O 2 production.