Magnesium single-atom catalysts with superbasicity

Magnesium-related solid bases have long been considered catalysts with weak or medium basicity. Here we report the fabrication of Mg single-atom catalysts with superbasicity for the first time. A sublimation-migration-anchoring strategy is employed, in which the Mg net is sublimated, transported by Ar, and trapped by defective graphene (producing Mg₁/G). Simulated and experimental results demonstrate that Mg single atoms are anchored on graphene in tetra-coordination, and Mg single atoms cooperating with C atoms give superbasicity, which differs from conventional alkali/alkaline earth metal oxides with basicity originating from O atoms. This new solid base is highly active in the synthesis of dimethyl carbonate through transesterification of ethylene carbonate with methanol, which is usually catalyzed by strong bases. The turnover frequency value reaches 99.6 h⁻¹ on Mg₁/G, which is much higher than that of traditional Mg-related counterparts (1.0–5.6 h⁻¹) and even superior to that of typical Na and K-related solid superbases (29.8–36.2 h⁻¹) under similar conditions. [Figure not available: see fulltext.].