Oxygen Reduction Reaction Performance of Co-Mn Spinel Composited with Various Substrates

Developing high-performance and durable non-precious metal catalysts for the oxygen reduction reaction (ORR) is crucial for advancing the commercialization of anion exchange membrane fuel cells (AEMFCs). Mn-Co spinel (MCS) represents a novel class of ORR electrocatalysts offering high activity, excellent long-term durability, and low cost. However, challenges such as particle agglomeration, limited electrical conductivity, and insufficient structural stability hinder their practical application. Modifying the microstructure and electronic properties of MCS via different supports presents an effective strategy to address these limitations. In this work, Mn_1.5Co_1.5O₄ nanoparticles were hydrothermally grown on three distinct supports—XC-72R carbon black, carbon nanotubes (CNTs), and Fe-N-C—to construct MCS/XC-72R, MCS/CNT, and MCS/Fe-N-C composite catalysts, thereby enhancing dispersion and conductivity for synergistic performance improvement. Electrochemical analysis reveals that compositing MCS with Fe-N-C significantly boosts AEMFC power output by constructing hierarchical porous architectures and strong interfacial electronic interactions, which synergistically increase active site density and mass transport efficiency. Conversely, while MCS/CNT exhibits improved intrinsic activity, its performance is limited by pore blockage induced by one-dimensional entanglement and increased hydrophilicity. These results demonstrate that rational design of the carrier-spinel interface effectively optimizes reaction kinetics and mesopore distribution, reinforcing mass transport and ultimately enhancing device power output.