Defective C3N4 frameworks coordinated diatomic copper catalyst: Towards mild oxidation of methane to C1 oxygenates

Abstract

Mild conversion of CH4 to value-added chemicals remains a grand challenge due to its chemical inertness. We report the N-defective C3N4 confined diatomic Cu (Cu2@C3N4-D) catalysts for the efficient oxidation of CH4 to C1 oxygenates at low temperature. With photo-irradiation, the carbon atoms neighbouring defects of C3N4 can anchor the second Cu by Cu-C2N bonding. Cu2@C3N4-D exhibits C1-oxygenates STY up to 4878 μmol gcat−1 h−1 with TOF of 83 h−1 at 50 °C, which is 300% higher than that of single atomic catalysts and even better than the reported noble-metal catalysts. The catalyst stability is also proved. Both experiments and computations demonstrate that the diatomic Cu pairs are toughly packed in asymmetrical [N3-Cu]···[Cu-C2N] with + 1 charge for Cu, endowing the catalyst with unique synergistic effects on CH4 activation. It provides a simple way to construct active sites with well-controlled atom number and enlightens the defect functionalization for catalyst design.