Constructing Co–N–C Catalyst via a Double Crosslinking Hydrogel Strategy for Enhanced Oxygen Reduction Catalysis in Fuel Cells

Exploiting platinum‐group‐metal (PGM)‐free electrocatalysts with remarkable activity and stability toward oxygen reduction reaction (ORR) is of significant importance to the large‐scale commercialization of proton exchange membrane fuel cells (PEMFCs). Here, a high‐performance and anti‐Fenton reaction cobalt–nitrogen–carbon (Co–N–C) catalyst is reported via employing double crosslinking (DC) hydrogel strategy, which consists of the chemical crosslinking between acrylic acid (AA) and acrylamide (AM) copolymerization and metal coordinated crosslinking between Co2+ and P(AA–AM) copolymer. The resultant DC hydrogel can benefit the Co2+ dispersion via chelated Co‐N/O bonds and relieve metal agglomeration during the subsequent pyrolysis, resulting in the atomically dispersed Co‐Nx/C active sites. By optimizing the ratio of AA/AM, the optimal P(AA–AM)(5‐1)–Co–N catalyst exhibits a high content of nitrogen doping (12.36 at%) and specific surface area (1397 m2 g−1), significantly larger than that of the PAA–Co–N catalyst (10.59 at%/746 m2 g−1) derived from single crosslinking (SC) hydrogel. The electrochemical measurements reveal that P(AA–AM)(5‐1)–Co–N possesses enhanced ORR activity (half‐wave potential (E1/2) ≈0.820 V versus the reversible hydrogen electrode (RHE)) and stability (≈4 mV shift in E1/2 after 5000 potential cycles in 0.5 m H2SO4 at 60 ºC) relative to PAA‐Co‐N, which is higher than most Co–N–C catalysts reported so far. In this study, a high‐performance and anti‐Fenton reaction Co–N–C catalyst is exploited via employing the chemical and metal‐coordinated double crosslinking hydrogel strategy. The electrochemical results reveal that the as‐prepared Co–N–C catalyst possesses enhanced oxygen reduction reaction activity and stability relative to the catalyst derived from single crosslinking in half‐cell and fuel cell.