Asymmetrically coordinated cobalt single atom on carbon nitride for highly selective photocatalytic oxidation of CH4 to CH3OH

By breaking structural symmetry of the single atomic active site, the photocatalytic water oxidation pathway is tuned for highly selective oxidation of CH 4 to CH 3 OH in an aqueous solution. The water oxidation ability and its influence on photocatalytic oxidation of CH 4 over symmetrically coordinated cobalt single atom (Co-4N) on carbon nitride (SC-Co 1 /PCN) and asymmetrically coordinated cobalt single atom (Co-C2N2) on carbon nitride (AC-Co 1 /PCN KOH ) photocatalysts are systematically investigated. A super selectivity of 87.22% for photocatalytic oxidation of CH 4 to CH 3 OH is realized on AC-Co 1 /PCN KOH , which is only 45% on SC-Co 1 /PCN. Moreover, a CH 4 conversion of 2.42% and a CH 3 OH yield of 2.11% are achieved over AC-Co 1 /PCN KOH (200 mg). Combining multiple in-situ characterizations and time-dependent density functional theory calculations, it is revealed that AC-Co 1 /PCN KOH possesses a desired electronic configuration for single-electron transfer water oxidation reaction during photocatalysis, leading to a notably promoted selectivity for CH 4 oxidation to CH 3 OH under illumination.