Insights into elusive and cooperative multi-oxidant mechanisms in enabling catalytic methane-to-methanol conversion over atomically dispersed metals

NO_x 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 NO_x in oxidizing methane is the interconversion of various NO_x compounds as well as the easy formation of O₂, 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 O₂, 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.