Fabrication of FeO3 sites in FeOx/ZnO for efficient and selective photo-catalytic oxidation of methane to liquid oxygenates

New catalysts and product diversification of direct CH 4 conversion remain very challenging in catalysis. Here, we report FeO x /ZnO photo-catalysts for the conversion of CH 4 to liquid oxygenates with high yield (4,108 μmol·g cat −1 ·h −1 ) and nearly 100% selectivity. Based on the combinative results from X-ray photoelectron spectroscopy, X-ray absorption, electron paramagnetic resonance, radical quenching, and theoretical calculations, it is found that, in addition to the activation of CH 4 in the liquid phase, the presence of highly dispersed FeO 3 motifs in the ZnO lattice facilitates the formation of surface-active O − species; this plays an effective role for CH 4 activation to · CH 3 radicals. Meanwhile, HCHO is obtained as the major product in our system, rather than the typically reported CH 3 OH, and this may offer new opportunities to extend the product structure of CH 4 upgrading via tandem catalysis.