No abstract

Metal‐free carbons have been regarded as one of the promising materials alternatives to precious‐metal catalysts for oxygen reduction reaction (ORR) due to their high activity and stability. In this paper, well‐defined N‐doped hollow carbons (NHCs) are firstly synthesized by using an ammonia‐based hydrothermal synthesis that is environmentally friendly and suitable for mass production in industry and a commercial black carbon as raw material. Moreover, the shell thickness of the NHCs can be easily tuned by this hydrothermal strategy. Zn–air battery test results reveal shell thickness‐dependent activity and durability for ORR over the NHCs, which exceeds that obtained by commercial Pt/C (20 wt %). The enhanced battery performance can be attributed to the curvature‐activated N–C moieties on the hollow carbon surface, which served as the main active sites for ORR as evidenced by DFT calculations. The proposed approach may open a way for designing curved hollow carbons with high graphitization degree and dopant nitrogen level for metal–air batteries or fuel cells.