The development of advanced transition metal/nitrogen/carbon-based (M/N/C) catalysts with high activity and extended durability for oxygen reduction reaction (ORR) is critical for platinum-group-metal (PGM) free fuel cells but still remains great challenging. In this review, we summarize the recent progress in two typical M/N/C catalysts (atomically dispersed metal-nitrogen-carbon (M-N-C) catalysts and carbon-supported metal nanoparticles with N-doped carbon shells (M@NC)) with an emphasis on their potential applications in fuel cells. Starting with understanding the active sites in these two types of catalysts, the representative innovative strategies for enhancing their intrinsic activity and increasing the density of these sites are systematically introduced. The synergistic effects of M-N-C and M@NC are subsequently discussed for those M/N/C catalysts combining both of them. To translate the material-level catalyst performance into high-performance devices, we also include the recent progress in engineering the porous structure and durability of M/N/C catalysts towards efficient performance in fuel cell devices. From the viewpoint of industrial applications, the scale-up cost-effective synthesis of M/N/C catalysts has been lastly briefed. With this knowledge, the challenges and perspectives in designing advanced M/N/C catalysts for potential PGM-free fuel cells are proposed.

先进的过渡金属/氮/碳基（M / N / C）催化剂的开发对氧还原反应（ORR）具有高活性和延长的耐久性，对于不含铂族金属（PGM）的燃料电池至关重要，但仍然存在巨大的挑战。在这篇综述中，我们总结了两种典型的M / N / C催化剂（原子分散的金属氮碳（MNC）催化剂和具有N掺杂碳壳（M @ NC）的碳载金属纳米颗粒）的最新进展，强调其在燃料电池中的潜在应用。从了解这两种催化剂中的活性位点开始，系统地介绍了增强其固有活性和增加这些位点密度的代表性创新策略。随后将讨论MNC和M @ NC的协同作用，以结合它们的M / N / C催化剂。为了将材料级催化剂的性能转化为高性能设备，我们还包括了M / N / C催化剂的多孔结构和耐用性工程设计的最新进展，以实现燃料电池设备的高效性能。从工业应用的角度出发，最后简要介绍了按比例扩大的具有成本效益的M / N / C催化剂的合成方法。以此知识，提出了为潜在的无PGM燃料电池设计先进的M / N / C催化剂的挑战和前景。我们还包括最近在工程化M / N / C催化剂的多孔结构和耐久性方面取得的进展，以提高燃料电池设备的性能。从工业应用的角度出发，最后简要介绍了按比例扩大的具有成本效益的M / N / C催化剂的合成方法。以此知识，提出了为潜在的无PGM燃料电池设计先进的M / N / C催化剂的挑战和前景。我们还包括在工程化M / N / C催化剂的多孔结构和耐久性方面取得的最新进展，以提高燃料电池设备的性能。从工业应用的角度出发，最后简要介绍了按比例扩大的具有成本效益的M / N / C催化剂的合成方法。以此知识，提出了为潜在的无PGM燃料电池设计先进的M / N / C催化剂的挑战和前景。