Graphene-anchored sodium single atoms: A highly active and stable catalyst for transesterification reaction

Solid strong base catalysts have received considerable attention in various organic reactions due to their facile separation, neglectable corrosion, and environmental friendliness. Although great progress has been made in the preparation of solid strong base catalysts, it is still challenging to avoid basic sites aggregation on support and active sites loss in reaction system. Here, we report a tandem redox strategy to prepare Na single atoms on graphene, producing a new kind of solid strong base catalyst (Na1/G). The base precursor NaNO3 was first reduced to Na2O by graphene (400 °C) and successively to single atoms Na anchored on the graphene vacancies (800 °C). Owing to the atomically dispersed of basicity, the resultant catalyst presents high activity toward the transesterification of methanol and ethylene carbonate to synthesize dimethyl carbonate (turnover frequency (TOF) value: 125.7 h−1), which is much better than the conventional counterpart Na2O/G and various reported solid strong bases (TOF: 1.0–90.1 h−1). Furthermore, thanks to the basicity anchored on graphene, the Na1/G catalyst shows excellent durability during cycling. This work may provide a new direction for the development of solid strong base catalysts.