Decoding the coordination environment engineering of non-noble metal-nitrogen-carbon: from microstructure to oxygen electrocatalytic performance

The development of highly efficient non-precious metal-nitrogen-carbon (M-N-C) electrocatalysts is a key scientific issue for improving the performance of metal-air batteries and fuel cells. Due to the symmetric charge distribution of the traditional M-N₄ active site, the adsorption energy of the key oxygen intermediates in the process of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is difficult to reach the optimal value, which seriously limits the catalytic efficiency. The core of solving this problem lies in the accurate modulation of the coordination environment of the M-N₄ site, which can realize the breakthrough improvement of the catalytic performance by synergistically optimizing the geometric configuration and electronic structure. In this paper, we systematically analyze the ORR/OER reaction mechanism and then comprehensively review the four main strategies to optimize the coordination environment of M-N-C: metal site regulation, coordination number engineering, non-metal atom doping, and carbon support regulation. Through an in-depth analysis of the structure–activity relationship between the coordination configuration and catalytic performance, the core challenges faced by current research are pointed out, and future research directions are envisioned. This work aims to provide theoretical references for the directional construction of highly efficient M-N-C catalysts with optimized coordination environments.