Multiscale designing principle of M-N-C towards high performance PEMFC

Among the reported non-precious-metal catalysts, metal-nitrogen-carbon (M-N-C) catalysts have emerged as a research cornerstone in the field of electrocatalysis, showcasing unparalleled activity in oxygen reduction reactions that rivals or even exceeds that of commercial Pt catalysts. Despite boasting high atom utilization and adjustable effective activity centers, M-N-C catalysts suffer from inadequate long-term stability under high-pressure and harshly acidic conditions within proton exchange membrane fuel cells (PEMFCs). This drawback poses a significant challenge that critically limits their potential for widespread applications. From this perspective, we commence by delineating the pivotal strategies to augment the performance of M-N-C catalysts at the microscopic level, including the tuning of the intrinsic activity of individual active sites and the manipulation of their quantity. Furthermore, we delve into the benefits derived from the synergistic effects unleashed by the incorporation of multi-component active sites. At the mesoscopic level, this perspective engages with the design principles aimed at enhancing the activity and stability of M-N-C catalysts within the intricate three-phase boundary of PEMFCs. Ultimately, we prospect the opportunities and challenges facing the future evolution of M-N-C catalysts, with the aim of offering comprehensive guidance for the design and advancement of highly stable M-N-C catalysts tailored for PEMFC applications.