Chen Chang, Li Yifan, Cheng Dan, He Hua, Zhou Kebin
School of Chemical Sciences, National Engineering Laboratory for VOCs Pollution Control Material & Technology, University of Chinese Academy of Sciences, Beijing 100049, P. R. China.
ACS Appl Mater Interfaces. 2020 Sep 9;12(36):40415-40425. doi: 10.1021/acsami.0c12801. Epub 2020 Aug 25.
The inferior stability of bifunctional oxygen electrocatalysts in the air cathode is one of the main obstacles that impedes the commercialization of zinc-air batteries (ZABs). This work describes a self-assembly technique combined with subsequent calcination to prepare a bifunctional oxygen electrocatalyst of graphite nanoarrays-confined Fe and Co single-atoms within graphene sponges (FeCo-NGS). Specifically, graphene sponges overspread with graphite nanoarrays as a structure regulation, which can prevent the metal single-atoms from aggregating and accelerate the mass/electron transfer, provides a guarantee for the long-term operation. Furthermore, M-N (M = Fe/Co) as the intrinsic activity regulation can effectively drive the heterogeneous oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalytic processes. Thanks to the rationally designed regulations, FeCo-NGS shows both extraordinary electrocatalytic activity for ORR and OER, even outperforming commercial Pt/C and IrO. Remarkably, ZABs with FeCo-NGS air cathode demonstrate a record-breaking cycle lifetime of more than 1500 h (over 9000 cycles) at 10 mA cm with a small charge-discharge gap.
双功能氧电催化剂在空气阴极中的稳定性较差是阻碍锌空气电池（ZABs）商业化的主要障碍之一。这项工作描述了一种自组装技术，结合后续煅烧，制备了一种石墨烯海绵（FeCo-NGS）中石墨纳米阵列限制的铁和钴单原子双功能氧电催化剂。具体而言，覆盖有石墨纳米阵列的石墨烯海绵作为一种结构调控手段，可以防止金属单原子聚集并加速质量/电子转移，为长期运行提供了保障。此外，M-N（M = Fe/Co）作为本征活性调控手段，可以有效驱动异相氧还原反应（ORR）和析氧反应（OER）的催化过程。得益于合理设计的调控手段，FeCo-NGS对ORR和OER均表现出非凡的电催化活性，甚至优于商业Pt/C和IrO。值得注意的是，具有FeCo-NGS空气阴极的ZABs在10 mA cm下表现出超过1500 h（超过9000次循环）的破纪录循环寿命，充放电间隙很小。
