铁锰双金属协同增强碳基催化剂的氧还原性能及锌空气电池应用

Iron-Manganese Bimetallic Synergy Boosted Carbon-Based Catalysts for Oxygen Reduction and Zinc-Air Battery Applications

  • 摘要: 单金属活性位点本征活性不足,严重制约了催化剂性能的进一步提升。因此,构建双金属协同活性位点、调控活性中心电子结构,成为突破单金属 M-N-C 催化剂性能瓶颈的有效途径。本研究以二氧化硅为硬模板制备氮掺杂多孔碳球载体,通过浸渍 - 还原法制备出 FeMn-N-C 双金属电催化剂,并系统对比其与单金属 Fe-N-C、Mn-N-C 催化剂的氧还原催化性能。结果表明,Fe、Mn 双金属间存在显著的电子协同效应,可有效调控活性位点的电子与几何结构,加速氧还原反应(ORR)的动力学过程。FeMn-N-C 催化剂在碱性介质中展现出优异的 ORR 性能,半波电位可达 0.878 V,塔菲尔斜率低至 49.58 mV·dec−1,经 10000 s 稳定性测试后,电流密度仍能保持初始值的 91.9%。以该催化剂为空气阴极组装的柔性和水系锌空气电池,峰值功率密度分别达 159.4 mW·cm−2 和 270 mW·cm−2,综合性能显著优于商业 40% Pt/C 催化剂。本研究为开发低成本、高活性、高稳定性的非贵金属双金属 ORR 电催化剂提供了设计思路,并拓宽了其在锌空气电池中的应用。

     

    Abstract: The insufficient intrinsic activity of single-metal active sites severely restricts the further improvement of catalyst performance. Therefore, constructing bimetallic synergistic active sites and regulating the electronic structure of active centers have become effective approaches to break through the performance bottleneck of single-metal M-N-C catalysts. In this study, nitrogen-doped porous carbon sphere supports were prepared using silica as a hard template, and FeMn-N-C bimetallic electrocatalysts were synthesized via an impregnation-reduction method. The oxygen reduction reaction (ORR) catalytic performance of the FeMn-N-C catalyst was systematically compared with that of single-metal Fe-N-C and Mn-N-C catalysts. The results demonstrate that there exists a significant electronic synergistic effect between Fe and Mn bimetals, which can effectively regulate the electronic and geometric structures of active sites and accelerate the kinetic process of the oxygen reduction reaction (ORR). The FeMn-N-C catalyst exhibits excellent ORR performance in alkaline media, with a half-wave potential of 0.878 V and a Tafel slope as low as 49.58 mV·dec−1. The current density can still maintain 91.9% of its initial value after 10000 s. The flexible and aqueous zinc-air batteries assembled with this catalyst as the air cathode achieve peak power densities of 159.4 mW·cm−2 and 270 mW·cm−2, respectively, and their comprehensive performance is significantly superior to that of the commercial 40% Pt/C catalyst. This study provides a design strategy for the development of low-cost, high-activity, and high-stability non-noble metal bimetallic ORR electrocatalysts, and broadens their application prospects in zinc-air batteries.

     

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