Hierarchically porous carbon confined cobalt nanoparticles for highly efficient oxidative esterification of 5‐hydroxymethylfurfural

Abstract Herein, we report a controllable and versatile strategy for the synthesis of highly dispersed Co nanoparticles embedded in open‐channel hierarchically porous N/O‐doped carbon skeleton. Moreover, the pore sizes of the hierarchical structures can be easily tuned by adjusting the size of precursors. The as‐obtained Co@NC‐2ST exhibits unprecedented activity and selectivity in the oxidative esterification of 5‐hydroxymethylfurfural (HMF) to dimethyl furan‐2,5‐dicarboxylate under base‐free and atmospheric conditions. In particular, the achieved turnover frequency value is an order of magnitude higher than that of the state‐of‐art heterogeneous catalysts reported to date. A combination of experimental and density function theory studies reveals that the unique features of Co@NC‐2ST enable a novel reaction route, that is, the CHO group of HMF is preferentially esterified instead of the OH group. This can be attributed to the nucleophilic addition reaction caused by the attack of methoxy anion on the CHO group of HMF.