Transition metal–nitrogen–carbon (M–N–C) catalysts have attracted significant attention for catalyzing oxygen reduction reactions (ORR). In this study, a porous Cr₂O₃@Cr–N–C catalyst with a small amount of Cr₂O₃ nanoparticles loaded on the surface of Cr–N₄–C nanomaterials was prepared using synergistic heat treatment (SHT) method with zeolite imidazole frameworks (ZIFs) as precursors. TEM and spherical aberration-corrected TEM results demonstrated the presence of hollow morphologies, Cr₂O₃ nanoparticles and atomic-level Cr distribution in Cr₂O₃@Cr–N–C. XPS, XRD and XAFS analysis indicated the coexistence of Cr₂O₃ nanoparticles and Cr–N₄ sites which were believed to act as active centers for ORR. In 0.1 M HClO₄, this material showed outstanding ORR catalytic activity with a half-wave potential of 0.78 V that was 40 mV higher than the traditional heat treatment derived Cr–N–C. It also revealed relatively low Tafel slope of 52.2 mV dec⁻¹; 4-electron pathway; remarkable stability and long-term durability. The improved ORR performance is mainly attributed to the synergy between Cr–N₄ active center and Cr₂O₃ nanoparticle. The SHT strategy reported here provides a new route to prepare highly efficient non-precious metal M−N–C catalysts with greater ORR activity and stability in acidic environments.

过渡金属-碳-氮（MC）催化剂在催化氧还原反应（ORR）方面引起了极大的关注。在这项研究中，使用协同热处理（SHT）方法制备了一种多孔Cr ₂ O ₃ @ Cr–N–C催化剂，该催化剂中少量的Cr ₂ O ₃纳米颗粒负载在Cr–N ₄ –C纳米材料的表面上。沸石咪唑骨架（ZIF）作为前体。TEM和证明中空形态的存在球面像差校正的TEM结果，铬₂ ö ₃纳米颗粒和原子级分布的Cr以Cr ₂ ö ₃@ Cr–N–C。XPS，XRD和XAFS分析表明Cr ₂ O ₃纳米颗粒和Cr–N ₄位点并存，据信它们是ORR的活性中心。在0.1 M HClO _4中，该材料显示出出色的ORR催化活性，其半波电势为0.78 V，比传统热处理得到的Cr–N–C高40 mV。它也显示出较低的Tafel斜率，为52.2 mV dec ^-1 ; 4-电子途径 出色的稳定性和长期耐用性。ORR性能的提高主要归因于Cr–N ₄活性中心与Cr ₂ O ₃的协同作用纳米颗粒。本文报道的SHT策略为制备高效的非贵金属M-N-C催化剂提供了一条新途径，该催化剂在酸性环境中具有更强的ORR活性和稳定性。