Pyrolyzed M-Nx catalysts for oxygen reduction reaction: progress and prospects

Fuel cells, a sustainable technology that assures a cleaner earth, once experienced disillusion due to the issue of economic viability associated with the massive usage of Pt-based catalysts. To address this issue, research on cost-effective catalysts, especially on the cathode side, has been intensively carried out where the latest achievements have made the M-N-x/C material on its verge of application. Here, we present a comprehensive overview of the fundamental chemistry of oxygen reduction reaction (ORR) and the progress of the M-N-x/C catalysts. Efforts aimed at clarifying the nature of catalytic sites are summarized, highlighting the indispensable role of advanced characterization tools. A variety of successful attempts are exemplified to describe the synthetic methodologies, followed by close tracking of newly emerging single-atom or dual-atom sites. Future directions for this research area are believed to be the rational and/or controllable synthesis of catalysts with adequate active sites and the use of strategies to substantially alleviate catalyst degradation.

Automated summary

Recent research efforts on cost-effective catalysts in fuel cells, especially on the cathode, have shown promising advancements in the development of M-N-x/C materials. The focus has been on clarifying the nature of catalytic sites and utilizing advanced characterization tools to optimize synthesis methodologies. Future directions aim to achieve rational and controllable synthesis of catalysts with sufficient active sites and strategies to mitigate catalyst degradation.