FeCu dual-single-atom catalyst promotes gradient H₂O₂ activation for enhanced methane oxidation to methanol

Hydrogen peroxide is an attractive and sustainable oxidant, yet its effective application in inert alkane oxidation is limited by the inability to precisely match the distribution, concentration, and reactivity of generated oxygen species with substrate activation requirements. Herein, a dual single-atom catalyst, FeCu/ZSM-CI, in which atomically dispersed Fe and Cu are spatially separated within the microporous framework of ZSM-5, with Fe located in the inner channels and Cu on the external surface, thereby enabling a controlled H₂O₂ activation gradient. This spatial configuration induces differentiated reactive oxygen species evolution: high-valent Fe=O and •OOH species form in the interior to activate methane into CH₃OOH, while surface Cu sites selectively convert CH₃OOH into methanol, mitigating overoxidation pathways. The optimized FeCu/ZSM-CI catalyst achieves a methanol yield of 20.2 mmol g_cat^-1 h^-1 with 90.1% selectivity and a remarkable H₂O₂ utilization efficiency of 74.6%. Mechanistic studies combining kinetic isotope effects, scavenger assays, in-situ EPR/DRIFTS, and DFT calculations reveal that Fe-Cu synergy shifts the rate-determining step from H₂O₂ activation to C-H bond activation. These findings establish a generalizable strategy for manipulating ROS spatial distribution via spatial-configuration-driven synergy and a transferable design principle, offering new insights for designing advanced catalysts for selective hydrocarbon oxidation under ambient conditions.