Largely Promoted C–H Activation in Methane with O2 via d-Orbital Hybridization Induced by CuOx Supported on ZnO

Efficiently converting methane (CH4) to C1 products such as CH3OH, HCHO, and CH3OOH is considered a promising route for the chemical industry, while the huge challenge of low CH4 activation rate still remains. Here, the promising Cu/ZnO composite catalyst with CuOx supported on ZnO is synthesized to modify the electronic structure and utilized for CH4 conversion. The fast e– transfer channel of ZnO → Cu → O2 facilitates O2 dissociation to •OOH, which promotes charge separation and, in parallel, enables CH4 oxidation to •CH3 by h+ left in ZnO with the acceleration effect of in situ generated •OOH. Mechanistic studies revealed that additional d-π*/d-σ-orbital hybridization between the catalyst and adsorbed O2/CH4 molecules plays decisive roles in O2 and CH4 activation, which resulted in the highest •CH3 signal, so far as we know, and ultimately a remarkably high C1 products yield of 21.25 mmol g–1 h–1 with 100% selectivity over the optimized 1 wt % Cu/ZnO photocatalyst. This work offers valuable guidance for catalyst designation in CH4 conversion in the presence of O2.