Abstract
M-N-C catalysts, with their transition metal atoms coordinated to nitrogen/carbon atoms as active sites, are gaining attention for their versatile heterogeneous electrocatalysis. Fabrication of these catalysts can be achieved through either bottom-up chemical synthesis or top-down pyrolysis procedures, where the former offers a well-defined structure and precise synthesis feasibility. This Perspective provides an overview of the history of the technical route dispute between pyrolysis and pyrolysis-free M-N-C catalysts, along with their respective advantages and disadvantages. Additionally, we emphasize the advantages of pyrolysis-free M-N-C catalysts, exemplified by several studies focused on precisely modulating the structure to regulate the activity, as well as the efforts of effectively integrating the active sites. Finally, we discuss the challenges and opportunities of pyrolysis-free M-N-C catalysts, with the aim of maximizing their inherent strengths of precise structure and promoting their industrial applications.