Gold nanoparticles supported on ZnGa2O4 nanosheets as efficient photocatalysts for selective oxidation of methane to ethane under ambient conditions

Abstract

In this study, we fabricated photocatalysts comprising of ZnGa2O4 nanosheets modified with gold (Au) nanoparticles for the selective oxidative coupling of methane (CH4). Our findings indicate that the C2H6 production rate of ZnGa2O4 with the optimal loading of Au nanoparticles (NPs) reached 1315.3 μmol g–1 h–1, with a selectivity of 53 %. These results were considerably higher than those obtained with pure ZnGa2O4. The presence of Au NPs facilitated the activation of O2 molecules, leading to the generation of superoxide ions (O2–), which were the primary active species responsible for the cleavage of CH4 into methyl radicals (•CH3). Additionally, Au NPs stabilized •CH3 and promoted the coupling of •CH3 into C2H6 while impeding the excessive oxidation of •CH3 into CO2. In conclusion, our study demonstrates that modifying ZnGa2O4 with Au NPs can significantly enhance the yield and selectivity of C2H6 during the photocatalytic oxidative coupling of CH4.