ABSTRACT
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 Cu2@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 (O2) being used as the oxidizer, respectively. In particular, the photocatalytic oxidation of CH4 with O2 achieves >10% conversion, and >98% selectivity toward methyl oxygenates and a mass-specific activity of 1399.3 mmol g Cu-1h-1. Mechanistic studies reveal that the high reactivity of Cu2@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 O2 activation in thermo- and photocatalysis, respectively.
