A series of ZIF-67-C-IL catalysts were prepared using ZIF-67 and 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide ([ BMIM]NTf2) ionic liquid as precursors. The structure of the catalysts was characterized by XRD, TEM, SEM and XPS. The catalytic performance of the catalysts for the oxygen reduction reaction (ORR) was evaluated in a three-electrode system. The results confirmed that the high-temperature treatment of the precursors resulted in the formation of N, S codoped carbon-encapsulated Co9S8 nanoparticles. To create N, S co-doped carbon coated Co9S8 nanoparticle catalysts, ionic liquids are used as sulfur and nitrogen sources. The catalytic activity of ORR can be improved using N, S co-doped carbon to prevent the aggregation of Co9S8 nanoparticles. Graphitized and N, S co-doped carbon shells are optimal for achieving high activity stability. Optimal 600-ZIF-67-C(1:1.5)-30IL catalytic activity was observed for ORR. The half-wave potential of ORR was 0.88 V vs. RHE in 0.1 mol L− 1 KOH, with a limit current density of 4.70 mA cm− 2. Similar ORR electrocatalytic activity was observed between this catalyst and commercial Pt/C (20 wt%).

Ionic liquidZIF-67 derived Co9S8-SNC catalyst for oxygen reduction reaction in alkaline electrolyte
    Abstract
    1 Introduction
    2 Experimental section
        2.1 Materials
        2.2 Preparation of catalysts
        2.3 Materials characterizations
        2.4 Electrochemical measurements
    3 Results and discussion
        3.1 Physicochemical characterizations
        3.2 Electrocatalytic performances
    4 Conclusion
    Acknowledgements 
    References

• Qiuyue Gao(Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China)
• Guoru Li(Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China)
• Gideon Kofie(Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China)
• Biaohua Chen(Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China)
• Fengxiang Yin(Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China)