Lv Mengyao, Guo Haichuan, Shen Hangjia, Wang Jun, Wang Jiacheng, Shimakawa Yuichi, Yang Minghui
Institute of New Energy Technology, Ningbo Institute of Industrial Technology, Chinese Academy of Sciences, Ningbo 315201, China.
College of Chemistry, Liaoning University, Shenyang 110036, China.
Phys Chem Chem Phys. 2020 Apr 8;22(14):7218-7223. doi: 10.1039/d0cp00109k.
A key challenge in carrying out an efficient oxygen reduction reaction (ORR) is the design of a highly efficient electrocatalyst that must have fast kinetics, low cost and high stability for use in an energy-conversion device (e.g. metal-air batteries). Herein, we developed a platinum-free ORR electrocatalyst with a high surface area and pore volume via a molten salt method along with subsequent KOH activation. The activation treatment not only increases the surface area to 940.8 m2 g-1 by generating lots of pores, but also promotes the formation of uniform Fe3C nanoclusters within the atomic dispersed Fe-Nx carbon matrix in the final material (A-FeNC). A-FeNC displays excellent activity and long-term stability for the ORR in alkaline media, and shows a greater half-wave potential (0.85 V) and faster kinetics toward four-electron ORR as compared to those of 20 wt% Pt/C (0.83 V). As a cathode catalyst for the Zn-air battery, A-FeNC presents a peak power density of 102.2 mW cm-2, higher than that of the Pt/C constructed Zn-air battery (57.2 mW cm-2). The superior ORR catalytic performance of A-FeNC is ascribed to the increased exposure of active sites, active single-atom Fe-N-C centers, and enhancement by Fe3C nanoclusters.
开展高效氧还原反应（ORR）的一个关键挑战是设计一种高效的电催化剂，该催化剂必须具备快速的动力学、低成本以及在能量转换装置（如金属空气电池）中使用时的高稳定性。在此，我们通过熔盐法并随后进行KOH活化，开发了一种具有高表面积和孔体积的无铂ORR电催化剂。活化处理不仅通过产生大量孔隙将表面积增加到940.8 m2 g-1，还促进了最终材料（A-FeNC）中原子分散的Fe-Nx碳基质内均匀的Fe3C纳米团簇的形成。A-FeNC在碱性介质中对ORR表现出优异的活性和长期稳定性，并且与20 wt% Pt/C（0.83 V）相比，显示出更大的半波电位（0.85 V）和更快的四电子ORR动力学。作为锌空气电池的阴极催化剂，A-FeNC的峰值功率密度为102.2 mW cm-2，高于Pt/C构建的锌空气电池（57.2 mW cm-2）。A-FeNC优异的ORR催化性能归因于活性位点、活性单原子Fe-N-C中心的暴露增加以及Fe3C纳米团簇的增强作用。
