Sheets Copper-Cobalt Graphitic Carbon Nitride Dual Single-Atom Catalysts for the Epoxidation of Styrene

Dual single-atom catalysts have attracted considerable research interest due to their higher metal atom loading and more flexible active sites compared to single-atom catalysts (SACs). We pioneered the one-step synthesis of sheets copper-cobalt graphitic carbon nitride dual single-atom (S−Cu/Co-g-C₃N₄) using folding fan-shaped aluminum foil as a template, and used them as catalysts in the epoxidation of styrene respectively. Through XAFS (X-ray Absorption Fine Structure) and other characterizations, it is found that Cu and Co single atoms are stabilized separately on g-C₃N₄ via coordination with nitrogen (N), hindered the ordered growth of sheets, and formed more pore structures, which not only increased more catalytically active sites, but also effectively prevented the flakes re-aggregate during the catalytic process. And the synergistic effect between Cu and Co changes the energy band structure of the material and facilitates electron transfer during catalysis, hence an excellent catalytic effect of 89 % styrene conversion and 85 % styrene oxide selectivity was achieved when S−Cu/Co-g-C₃N₄-1 : 1 was applied in the epoxidation of styrene. Furthermore, the mechanisms of the epoxidation of styrene with S−Cu/Co-g-C₃N₄-1 : 1 was probed by the density functional theory (DFT) based on the slab model.