Highly dispersed Co/N-rich carbon nanosheets for the oxidative esterification of biomass-derived alcohols: Insights into the catalytic performance and mechanism

Developing the active and environmentally friendly non-noble nano-catalysts is highly desired to transform biomass-derived platform into value chemicals. Herein, we report a low-cost and sustainable cobalt/nitrogen-doped carbon catalyst containing both metallic Co and Co-N components exhibits satisfying activity for the oxidative esterification of 5-hydroxymethylfurfural and other investigated alcohols in methanol without the base additive under mild conditions. Experimental results show that an appropriate ratio of Co to Co-N is responsible for the high activity of the Co/Co-N/CN catalysts towards oxidative esterification. Theoretical computational results demonstrate that the Co/Co-N group synergistically promotes electron transfer from the Co adatom to the surface oxygen atoms, facilitates O2 adsorption and activation on the Co sites, and further reduces the energy barrier for the oxidation of alcohols to aldehydes, all of which contribute to the overall activity of oxidative esterification of alcohols to the corresponding esters. In addition to exhibiting superior intrinsic activity, the as-prepared Co/Co-N/CN catalyst also shows excellent stability and recyclability.