Mesoporous and dual-shelled hollow CeO2@CoNC nanospheres as efficient and stable oxygen reduction reaction electrocatalysts

The electrocatalytic oxygen reduction reaction (ORR) is the key bottleneck of fuel cells and rechargeable metal-air batteries, and recently, metalnitrogen complex carbon (MNC) demonstrates great potential in these fields. However, the complex and easily degraded MNC structure often results in inferior activity and poor durability in electrolysis. Herein, we fabricate a catalyst of h-CeO2@CoNC through the extended Stöber method and subsequent pyrolysis, involving the hollow CeO2 as the core and CoNC as the shell. The h-CeO2@CoNC catalyst exhibits notable ORR catalytic performances in 0.1 M KOH with a half-wave potential of 0.82 V and excellent durability, attributed to the synergistic interaction between CeO2 and CoNC matrix. Specifically, the inner layer of CeO2 is principally responsible for enhancing the chemical stability and the outer one of CoNC matrix is beneficial to boosting the ORR catalytic activity. This work provides an efficient preparation approach and further insight of rational design of the unique MNC catalysts for energy storage.