Résumé
The success of the next generation of anion-exchange membrane fuel cells (AEMFCs) depends on the development of active, reliable, and economical oxygen reduction reaction (ORR) catalysts. Here, we synthesize a series of ultra-low-cost metal-free ORR catalysts by doping a common pristine graphite precursor with chemically singular-type heteroatoms, namely I, S, N, or B, using single-step planetary ball milling technique. All doped-graphites show substantially enhanced ORR performance relative to the pristine (undoped) graphite. Among all the tested catalysts, N-graphite exhibited the highest ORR onset potential of 0.87 V vs. reversible hydrogen electrode. These results are supported by density functional theory calculations. The ORR catalysts also exhibit remarkable stability as evaluated through electrochemical tests. Most importantly, the AEMFCs prepared using these ultra-low-cost doped graphites deliver notable peak power densities with impressive voltage efficiencies, which further supports their efficacy in ORR catalysis and the broad implementation of this technology.
[Display omitted]
•Highly active metal-free doped-graphite catalysts for alkaline ORR are developed.•Comprehensive alkaline ORR investigation by structural and DFT modeling.•Remarkable catalyst stability is shown by electrochemical and corrosion tests.•High-performance anion-exchange membrane fuel cells using metal-free cathodes.•Ultra-low-cost ORR metal-free catalyst materials and fabrication process.