长春应化所金属氮碳氧还原催化剂的研究进展

氧还原反应是燃料电池的核心,开发高性能催化剂一直是燃料电池技术面临的严峻挑战. 近年来,热解M-N-C催化剂的发展和以金属有机骨架材料为前驱体的运用让非贵金属氧还原催化剂的性能大幅度提升,但催化活性位点、反应机理等方面仍不甚清晰,需要分子水平上进一步的研究. 在这里,作者总结了本课题组近些年来在氧还原方向上的研究成果,首先是对催化剂活性位点进行的相关探索,提出了新的活性位点结构,为开发新型催化剂提供了帮助,并对金属氮碳催化剂进行了细致的微观调控,探讨了最佳的合成方法;其次开发了高效的双原子Co₂N₅催化剂,并在理论计算的指导下合成出了更为高效的FeCo双原子催化剂,具备了替代铂基催化剂的性能;最后针对芬顿反应引发的稳定性问题而开发的低芬顿反应活性的单原子Cr和单原子Ru催化剂,表现出了较高的活性和稳定性,为解决催化剂实际应用问题开辟了新的研究思路与方向. 作者相信,通过对催化剂活性位点的不断认知和对新型催化剂的不断开发,终会让非贵金属催化的商业化应用成为现实.

Research Progress of Metal-Nitrogen-Carbon Catalysts toward Oxygen Reduction Reaction inm Changchun Institute of Applied Chemistry

The development of highly active and stable catalysts toward oxygen reduction reaction (ORR) has been facing severe challenges. In recent years, pyrolytic M-N-C catalysts and metal-organic framework derived materials made the performance of non-noble metal catalysts greatly improved, however, the molecular and atomic level understanding in the reaction active sites and the mechanism are still lacking. Here, we summarize the recent research progress made in the Changchun Institute of Applied Chemistry. We present a microporous metal-organic-framework confined strategy toward the preferable formation of ORR catalysts. Firstly, we studied the active site and proposed a new active site structure for the Fe-N-C catalyst, which is helpful for the development of new catalyst. The M-N-C catalyst was carefully regulated and the best synthesis method was discussed; Secondly, a highly efficient binuclear Co₂N₅ catalyst was developed, which performs approximately 12 times higher activity than the conventional CoN₄ site and shows unprecedented catalytic activity in an acidic electrolyte with the half-wave potential of 0.79 V, presenting the best one among the Co-N-C catalysts, and a more efficient FeCo diatomic catalyst was synthesized under the guidance of theoretical calculation, indicating that the FeCoN₅—OH site enables the ORR onset potential and half-wave potential up to 1.02 and 0.86 V (vs. RHE), respectively, with an intrinsic activity over 20 times higher than the single-atom FeN₄ site; Finally, to overcome the stability problem caused by Fenton reaction, we developed novel single atomic Cr and Ru catalysts, showing low Fenton reaction activity, higher activity and stability after the accelerated degradation test for 20000 cycles, with the half-wave potentials being dropped only 15 and 17 mV, respectively, much lower than 31 mV of Fe-N-C catalysts. This offers a new way to solve the problem in catalyst application. We believe that upon further understanding in the active sites and the continuous development of new catalyst, the non-noble metal catalysts in PEMFCs will become truly applicable, which aids to solve the increasingly serious energy crisis environment.