Center for Advancing Electronics Dresden (Cfaed) and Department of, Chemistry and Food Chemistry, Technische Universität Dresden, 01062, Dresden, Germany.
State Key Laboratory for Manufacturing Systems Engineer, Xi'an Jiaotong University, Xi'an, 710049, P.R. China.
Chemistry. 2018 Dec 10;24(69):18413-18418. doi: 10.1002/chem.201804339. Epub 2018 Oct 30.
Owing to their high theoretical energy density, environmental benign character, and low cost, rechargeable Zn-air batteries have emerged as an attractive energy technology. Unfortunately, their energy efficiency is seriously plagued by sluggish oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) that alternately occurs on air electrodes. Herein, we demonstrate Co-based metal-organic framework (Co(bpdc)(H O) (bpdc=biphenyl -4, 4'-dicarboxylic acid), Co-MOF) arrays as novel bifunctional oxygen electrocatalysts. The Co-MOF is in situ constructed on a three-dimensional graphite foam (GF) through a hydrothermal reaction. In a 1 m KOH aqueous solution, the resultant Co-MOF/GF exhibits an OER overpotential of only ≈220 mV at 10 mA cm , which is much lower than those for Ir/C and previously reported noble metal-free electrocatalysts. In conjunction with its ORR half-wave potential of 0.7 V (vs. RHE), the Co-MOF/GF manifests a greatly decreased potential gap of ≈0.75 V in comparison with Pt/C-Ir/C couple and previously reported bifunctional oxygen electrocatalysts. Furthermore, an assembled rechargeable zinc-air battery using Co-MOF electrocatalyst in an air electrode delivers a maximum power density of 86.2 mW cm and superior charge-discharge performance. Microscopic, spectroscopic and electrochemical analyses prove that the initial Co-MOF is transformed into Co-oxyhydroxides during the OER and ORR process, which essentially serve as bifunctional active centers.
由于其高理论能量密度、环境友好特性和低成本，可充电锌空气电池作为一种有吸引力的能源技术而出现。不幸的是，它们的能量效率受到空气电极上交替发生的缓慢氧气析出反应 (OER) 和氧气还原反应 (ORR) 的严重困扰。在此，我们展示了基于钴的金属有机骨架 (Co(bpdc)(H O) (bpdc=联苯-4,4'-二羧酸)，Co-MOF) 阵列作为新型双功能氧电催化剂。Co-MOF 通过水热反应原位构建在三维石墨泡沫 (GF) 上。在 1 m KOH 水溶液中，所得的 Co-MOF/GF 在 10 mA cm 处表现出仅约 220 mV 的 OER 过电位，远低于 Ir/C 和以前报道的无贵金属电催化剂。结合其 ORR 半波电位为 0.7 V（相对于 RHE），Co-MOF/GF 的电位差大大降低，约为 0.75 V，与 Pt/C-Ir/C 对和以前报道的双功能氧电催化剂相比。此外，使用 Co-MOF 电催化剂作为空气电极的组装式可充电锌空气电池提供了 86.2 mW cm 的最大功率密度和卓越的充放电性能。微观、光谱和电化学分析证明，初始的 Co-MOF 在 OER 和 ORR 过程中转化为 Co-oxyhydroxides，它们本质上作为双功能活性中心。
