Insights into Elusive and Cooperative Multi-Oxidant Mechanisms in Enabling Catalytic Methane-to-Methanol Conversion Over Atomically Dispersed Metals

NOx is frequently invoked as an oxidant for direct selective conversion of methane into methanol (DSCMM), which has long been considered one of the holy grails in green chemistry. A challenge in studying the use of NOx in oxidizing methane is the interconversion of various NOx compounds as well as the easy formation of O-2, rendering it difficult to draw firm conclusions on the oxidant. Here, we explicitly elucidate the strengths of using dual oxidants (NO and N2O) for DSCMM over various phosphotungstic acid-supported single-atom catalysts. A competitive but cooperative multi-functional protocol involving dual oxidants is proposed to enhance catalytic performance due to its overall strong CH4 adsorption and thermodynamic favorability compared with normal mechanisms (single O-2, N2O, or NO). The new cooperative multi-functional mechanism strategy is expected to motivate further research to elaborate on its potential advantages in DSCMM and other relevant catalytic systems.