Target-Modified Main Catalytic Site of CuZn Dual-Atom Catalysts for Promoting Methane Oxidation to Methanol: A DFT Study

The oxidation of methane to methanol is a major challenge because of the high energy barrier for CH3–H bond activation, yet dual-atom catalysts have great potential in this regard. Based on density functional theory (DFT) calculations, it was found that the N3Zn-CuN4-DOPL catalyst target-modified with 2,5-dioxopyrrole significantly reduces the energy barrier of the CH3–H bond activation (0.69–0.34 eV), facilitating the oxidation of methane to methanol. The electronic properties calculations revealed that the Cu atom acts similar as electron reservoir and electron channel, and the existence of a strong σ-bond between the Cu atom and the N4 atom can substantially increase the amount of electron loss from the Cu atom, thus promoting the oxidation of methane to methanol. The special electronic phenomenon that N3Zn-CuN4-DOPL promotes the CH3–H bond activation was named as the "bowstring-release effect." That is, the Cu atom connected to the O* is equivalent to pulling the bowstring; the Cu atom releases the O*, which is equivalent to loosening the bowstring. This study provides useful guidance for regulating the catalytic activity by targeted modification of the main catalytic site of dual-atom catalysts.