Applying metal organic frameworks (MOFs) in electrochemical systems is a currently emerging field owning to the rich metal nodes and high specific surface area of MOFs. However, the problems for MOFs that need to be solved urgently are poor electrical conductivity and low ion transport. Herein, we present a facile in-situ growth method for the rational synthesis of MOFs@hollow mesoporous carbon spheres (HMCS) yolk-shell structured hybrid material for the first time. The size of the encapsulated ZIF-67 is well controlled to 100 nm due to the spatial confinement effect of HMCS and electrical conductivity of ZIF-67 is also increased significantly. The obtained ZIF@HMCS-25% hybrid material exhibits a highly efficient ORR activity with 0.823 V (vs. RHE) half-wave potential and even a higher kinetic current density (J_k = 13.8 mA cm⁻²) than commercial Pt/C. ZIF@HMCS-25% also displays excellent OER performance and the overpotential of ZIF@HMCS-25% at 10 mA cm^-2 is 407 mV. In addition, ZIF@HMCS-25% is further employed as an air electrode for a rechargeable Zn-air battery, exhibiting a high power density (120.2 mW cm^-2 at 171.4 mA cm^-2) and long-term charge/discharge stability (80 h at 5 mA cm^-2). Such MOFs@HMCS yolk-shell design provides a versatile method for the application of MOFs as electrocatalysts directly.

中文翻译：

---

将金属有机骨架封装到中空介孔碳球中作为高效氧双功能电催化剂

由于 MOF 具有丰富的金属节点和高比表面积，因此在电化学系统中应用金属有机框架 (MOF) 是目前新兴的领域。然而，MOFs亟待解决的问题是导电性差和离子传输低。在此，我们首次提出了一种简便的原位生长方法，用于合理合成 MOFs@中空介孔碳球（HMCS）蛋黄壳结构杂化材料。由于 HMCS 的空间限制效应，封装的 ZIF-67 的尺寸被很好地控制在 100 nm，并且 ZIF-67 的电导率也显着增加。获得的 ZIF@HMCS-25% 杂化材料表现出高效的 ORR 活性，具有 0.823 V (vs. RHE) 半波电位和更高的动电流密度 (J _k= 13.8 mA cm ^-2 ) 比商业 Pt/C。ZIF@HMCS-25% 还表现出优异的 OER 性能，ZIF@HMCS-25% 在 10 mA cm ^-2下的过电位为 407 mV。此外，ZIF @ HMCS-25％被进一步用作用于可再充电锌-空气电池的空气极，具有高功率密度（120.2毫瓦厘米^-2在171.4毫安厘米^-2）和长期的充电/放电的稳定性（80 小时在 5 mA cm ^-2）。这种 MOFs@HMCS 蛋黄壳设计为 MOFs 直接作为电催化剂的应用提供了一种通用的方法。