铠甲催化剂助力锌-空气电池:氮掺杂石墨烯上超薄碳封装铁镍合金增强氧电催化

Revolutionizing Zn‐Air batteries with chainmail catalysts:Ultrathin carbon‐encapsulated FeNi alloys on N‐doped graphene for enhanced oxygen electrocatalysis

改善氧还原反应(ORR)和氧析出反应(OER)的缓慢动力学对促进可充电锌-空气电池的应用具有重要意义.在过去十年中,研究人员致力于开发不含贵金属的双功能氧电催化剂,包括过渡金属(铁、钴、镍和锰)、合金、氧化物、氮化物、氢氧化物和磷化物,以进一步降低催化剂的成本,并提高其性能.研究表明,铁基催化剂表现出较好的ORR催化活性,而镍基催化剂在OER方面具有出色的性能,因此将铁和镍进行合金化组合成为一种实现高效双功能催化活性的有效方法.然而,反复的氧化还原反应会导致金属在水溶液中溶解,从而使得催化剂的耐久性变差.因此,如何在保证催化活性的同时提升催化剂的耐久性,成为了科研人员面临的一项重大挑战.构建铠甲催化剂被证明是解决上述问题的一种有效策略.本文通过热解三聚氰胺、葡萄糖和无机金属盐组成的混合物,成功制备了一种极具前景的铠甲催化剂FeNi@NC,其由掺杂氮的类石墨烯纳米片上超薄碳壳封装的铁镍合金纳米颗粒构成.扫描电镜、透射电镜、能量色散光谱、X射线吸收光谱和X射线衍射系列表征结果证明了碳壳封装铁镍合金纳米颗粒的形成,X射线光电子能谱证明催化剂中铁镍合金的电子向外层碳壳转移.电化学测试结果表明,FeNi@NC的ORR起始电位和半波电位与商业Pt/C催化剂相当,并且OER性能也与商业RuO2催化剂相近,展现出了良好的双功能催化活性.理论计算结果表明,内部铁镍合金的电子向外层氮掺杂碳壳转移,不仅活化了碳表面,还显著提升了催化剂的ORR和OER活性.这种电子转移促进了铁镍合金与氮掺杂碳壳之间的强协同效应,共同赋予了催化剂出色的双功能催化能力.此外,包裹在FeNi合金纳米颗粒周围的碳壳不仅为催化剂提供了结构支撑,还显著增强了易溶解合金物质的稳定性和耐久性.在多次循环伏安测试后,FeNi@NC催化剂仍然能够维持较高的催化性能,循环后的电镜表征进一步证实了催化剂结构的稳定性.FeNi@NC催化剂的高效催化活性、界面上快速的物质和电荷传输以及稳定的封装结构,使其在作为可充电锌-空气电池正极时展现出高功率密度和长循环稳定性.综上,本文研究了杂原子掺杂碳材料负载限域生长过渡金属合金的可控制备及其电催化反应机制,为锌-空气电池提供了一种新的解决方案.

The sluggish kinetics of the oxygen reduction reaction(ORR)and the oxygen evolution reaction(OER)pose significant challenges for the viability of rechargeable Zn-air batteries.Developing efficient,cost-effective,stable,and dual-purpose oxygen electrocatalysts remains a formidable hurdle.In this study,we successfully synthesized a highly promising chainmail catalyst named FeNi@NC,comprising ultrathin carbon shells encapsulating FeNi alloy nanoparticles on N-doped graphene-like nanosheets.The strong synergistic effects between FeNi alloys and N-doped carbon shells result in outstanding bifunctional catalytic activity,particularly in alkaline media.Consequently,Zn-air batteries incorporating FeNi@NC as the catalyst demonstrate exceptional performance,operating reliably at high power density with extended lifespan.Furthermore,computational analyses provided further confirmation of the catalytic activity and revealed that the electron transfer from FeNi alloy nanoparticles to the carbon shells activates the carbon surface,leading to enhanced catalytic performance.This research not only sheds light on the rational design and synthesis of heteroatom-doped carbon materials supporting the growth-constrained transition metal alloys but also offers a practical solution for advancing the application of Zn-air batteries.