Oxygen-Activated Dual-Atom Catalysts on Graphene for Direct Oxidation of Methane to Methanol: A DFT Study

The direct oxidation of methane (CH 4 ) to methanol (CH 3 OH) with molecular oxygen (O 2 ) as a green oxidant remains a formidable challenge, primarily due to the high energy barriers for the cleavage of the O–O bond and CH 3 –H bond activation. Here, we demonstrate that graphene-based dual-atom catalysts (TM1Zn-N P G, TM1 = Ti/V/Cr/Mn/Fe/Co/Ni/Cu) exhibit exceptional potential for this reaction. Through systematic density functional theory (DFT) calculations, FeZn-N P G is identified as the optimal catalyst, achieving a remarkably low energy barrier of 0.93 eV for the rate-limiting step ( O 2 – O* – CH 4 → O 2 – OH* – CH 3 • ). Mechanistic studies reveal that O 2 coadsorption on the FeZn-N P G-O* surface dynamically modulates the electronic structure of Fe sites, enabling their dual function as an electron reservoir to facilitate CH 3 –H bond activation (0.15 eV for O 2 * – CH 4 → O – OH* – CH 3 • ) and suppress overoxidation. Bader charge analysis, magnetic moments, and spin-polarized density of states (DOS) analyses further confirm the flexible electron transfer capability of the Fe site, which governs the catalytic activity and selectivity. This work establishes a design principle for O 2 -activated graphene-based dual-atom catalysts in the direct oxidation of CH 4 to CH 3 OH and advances the development of sustainable C1 chemistry.