Modulation of Single-Iron-Atom Coordination Environment Toward Three-Electron Oxygen Reduction for Photocatalytic CH4 Conversion to CH3OH.

By modifying the coordination environment of single-Fe-atom active site, effective regulation of the photocatalytic oxygen reduction pathway can be achieved to attain high activity for photocatalytic oxidation of CH4 to CH3OH in an aqueous solution. A comprehensive investigation is conducted to study the impact of different coordination numbers of single Fe atoms on photocatalytic CH4 oxidation reaction over carbon nitride. Among which, Fe1/C3-xN4 with a Fe-N3 coordination exhibit an exceptional photocatalytic performance in CH4 oxidation, reaching a remarkable methanol yield of 928.27 µmol gcat -1, much higher than Fe1/C3N4 and Fe1/C3N4-x (308.47 and 473.26 µmol gcat -1, respectively). Based on a collection of in situ characterizations and time-dependent density functional theory calculations, it is determined that Fe1/C3-xN4 with an optimal coordination number possesses the optimized electronic configuration that enables three-electron oxygen reduction to generate hydroxyl radicals for photocatalytic conversion of CH4 to CH3OH.