Coordination-tailored atomic interfaces for selective CH4-to-C2 conversion in aqueous solution

Selective CH₄-to-C₂ oxygenates conversion under mild conditions represents a frontier challenge in catalysis science with promising commercial implications. Herein, we report the successful and controlled construction of densely distributed O₂-bridged Fe diatomic (Fe₁-O₂-Fe₁) interfaces in carbon nitride aerogel-supported Fe dual-atom catalysts (Fe-DAC/g-C₃N₄) for selective methane oxidation to acetic acid (CH₃COOH) in aqueous solution under mild conditions. Experimental studies reveal that the Fe₁-O₂-Fe₁ atomic interfaces with tailored coordination environments and precisely modulated Fe-Fe distance (2.92 ± 0.05 Å) and oxygen-bridged coordination environment synergistically promote the activation and cleavage of C-H bond to form methyl radicals (•CH₃), carboxyl intermediates (•COOH), followed by selective C-C coupling via a radical recombination pathway. This concerted mechanism achieves unprecedented performance with near 100% selectivity and a remarkable CH₃COOH production rate of 0.79 mmol g_cat^-1 h^-1 under ambient conditions. Notably, industrially relevant pressures (1.5 MPa CH₄) elevate the production rate to 1.67 mmol g_cat^-1 h^-1 while maintaining >96% selectivity.