Carbon layers derived from zeolitic imidazolate framework crystal shells as a protective layer for Pt-based catalysts: Boosting oxygen reduction catalytic activity in fuel cells

Pt-based alloy catalysts are popular for fuel cell oxygen reduction reactions (ORRs) because of their high activity and low cost. However, during the preparation and reaction processes, metal nanoparticles tend to aggregate, which affects the activity and stability of the catalyst. To address this issue, this work uses Zeolite-type imidazolic acid framework material (ZIF) crystal shells to coat PtCu alloy catalysts, and N-doped nanoporous carbon layers derived from ZIFs are used to protect individual metal nanoparticles . The appropriate thickness of the ZIF-derived carbon protective layer is reported to effectively inhibit the aggregation of metal nanoparticles during high-temperature calcination , improve the utilization rate of Pt atoms and enhance the activity and stability of Pt-based catalyst. N-doping stabilizes the metal nanoparticles by enhancing their interaction with carriers. Electrochemical test results demonstrated that the mass activity of the prepared 3-Co-PtCu/NC is 6.9 times and 4.3 times that of commercial Pt/C and PtCu/C, respectively. Furthermore, the excellent half-wave potential is maintained even after 10,000 cycles. In single-cell test, the performance of 3-Co-PtCu/NC is better than Pt/C. This study provides a strategy for controlling the aggregation and detachment of metal nanoparticles in metal-based catalysts, which is conducive to improving the performance of catalysts.