可充电锌空气电池(ZABs)由于其高能量和功率密度、高安全性和成本效益, 被认为是未来储能领域中最有前途的清洁电源之一. 然而, 其实际应用受到放电和充电过程中氧还原反应(ORR)和析氧反应(OER)动力学缓慢的阻碍. Pt和IrO₂是目前公认的高效ORR和OER催化剂, 但贵金属催化剂的高成本阻碍了它们商业化的步伐. 本工作通过共沉淀法制备了一系列尖晶石催化剂(Mn_x-Co₃O₄, x=0, 0.5, 1, 1.5), 以实现在碱性介质中高效催化ORR和OER的目的, 并进一步探索这些过渡金属氧化物催化材料作为双功能复合催化剂在取代贵金属方面的潜力. 实验结果显示: Mn-Co₃O₄具有优异的ORR性能(起始电位为0.85 V, 半波电位为0.69 V)和OER性能(过电位为0.57 V, 电子转移电阻为26.14 Ω). 此外, 密度泛函理论(DFT)计算表明, Mn和Co位点可以分别作为ORR和OER的潜在活性位点, 在电催化过程中具有显著的协同作用. 表征结果进一步证实锰的掺杂增加了催化剂的比表面积和氧空位, 调整了催化剂表面化学和电子状态, 从而提高了催化剂的ORR和OER性能. 另外, 该催化剂在液态可充电锌空气电池中显示出长达40 h的循环寿命. 总而言之, 本工作证明了锰钴双金属协同催化是提高ORR和OER选择性的一种有效策略.

Rechargeable zinc-air batteries (ZABs) have been extensively studied due to their high energy and power density, high safety and cost-effectiveness, which are considered to be one of the most promising clean power sources in the field of energy storage. Nevertheless, its practical application has been hampered by the sluggish kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) during the discharge and charge processes, respectively. It is well known that Pt and IrO₂ are currently considered to be the most efficient ORR and OER catalysts. However, the high cost of precious metal catalysts has hindered their large-scale application. Herein, a series of spinel catalysts (Mn_x-Co₃O₄, x=0, 0.5, 1, 1.5) are prepared by co-precipitation method to achieve bifunctional oxygen electrocatalysis in alkaline media. Meanwhile, the potential of these transition metal oxide catalytic materials as bifunctional catalysts in replacing precious metals has been further explored. The results show that Mn-Co₃O₄ has excellent ORR performance (onset potential of 0.85 V, half-wave potential of 0.69 V), and significantly enhanced OER performance (overpotential of 0.57 V, the electron transfer resistance of 26.14 Ω), thereby leading to excellent bifunctional property. Furthermore, density functional theory (DFT) calculations demonstrate that Mn and Co sites can serve as potential active sites for ORR and OER respectively, exhibiting significant synergistic effects in electrocatalytic processes. The characterization results further confirm that the doping of manganese in the catalyst preparation process increases the specific surface area and oxygen vacancies of the catalyst, adjusts the surface chemistry and electronic state of the catalyst, and thus improves the ORR and OER performance of the catalyst. In addition, the Mn-Co₃O₄ catalyst delivers high cycle life of up to 40 h in liquid rechargeable zinc air batteries. In summary, this work demonstrates that manganese-cobalt bimetallic synergistic catalysis is a promising strategy to enhance the electrocatalytic activity of ORR and OER.