Oxo dicopper anchored on carbon nitride for selective oxidation of methane

Selective conversion of methane into value-added chemicals is a promising approach for utilization of hydrocarbon sources. Here the authors develop dimeric copper centers supported on graphitic carbon nitride (denoted as Cu-2@C3N4) with >10% conversion and >98% selectivity toward methyl oxygenates in both thermo- and photo- catalytic reactions. Selective conversion of methane (CH4) into value-added chemicals represents a grand challenge for the efficient utilization of rising hydrocarbon sources. We report here dimeric copper centers supported on graphitic carbon nitride (denoted as Cu-2@C3N4) as advanced catalysts for CH4 partial oxidation. The copper-dimer catalysts demonstrate high selectivity for partial oxidation of methane under both thermo- and photocatalytic reaction conditions, with hydrogen peroxide (H2O2) and oxygen (O-2) being used as the oxidizer, respectively. In particular, the photocatalytic oxidation of CH4 with O-2 achieves >10% conversion, and >98% selectivity toward methyl oxygenates and a mass-specific activity of 1399.3 mmol g Cu(-1)h(-1). Mechanistic studies reveal that the high reactivity of Cu-2@C3N4 can be ascribed to symphonic mechanisms among the bridging oxygen, the two copper sites and the semiconducting C3N4 substrate, which do not only facilitate the heterolytic scission of C-H bond, but also promotes H2O2 and O-2 activation in thermo- and photocatalysis, respectively.