(Invited) High Performance Fe/N/C-Based ORR Electrocatalyst and Its Application in Alkaline Fuel Cell

Abstract

Fe/N/C is a promising electrocatalyst for oxygen reduction reaction (ORR). This type catalyst can perform in both acidic and alkaline media. In acidic media, the active sites of Fe/N/C can be corroded; however, in alkaline media, Fe/N/C can exhibit high stability. Therefore, it is promising to explore the applications of Fe/N/C catalyst in alkaline fuel cell. Herein, we will talk about our recent advances in preparation of Fe/N/C catalysts and the application of them in alkaline fuel cells: (1) By using 2-aminothiazole, a molecule containing both N and S atoms, we prepared S co-doped Fe/N/C catalyst with graphene nanosheets. In alkaline solution, this catalyst exhibited high ORR activity with half-wave potential of 0.926 V and mass activity of 0.56 A g-1 @ 1.0 V. Furthermore, the catalyst displayed excellent durability, and only lost 9% of initial activity after 100 h of durability test at 0.80 V. In alkaline anion exchange membrane fuel cell (AEMFC) test, the peak power density could reach 164 mW cm−2. (2) We used the unzipped carbon nanotubes as carbon support and melamine as nitrogen source, and prepared a Fe/N/C catalyst with high ORR activity in alkaline media. The edge sites of unzipped carbon nanotubes play a key role for high catalyst activity. (3) we explored a series of nitrogen source including binary polymer of melamine-terethalaldehyde, ternary polymer of cynuric acid, 2, 4-diamino-6-phenyl-1, 3, 5-triazine, and melamine. N-doped carbon nanotubes with encapsulated Fe nanoparticles were prepared. The catalyst exhibited considerably high ORR activity in alkaline solution. We further tested its performance in alkaline membrane direct ethanol fuel cell, and the peak power density was about 64 mW cm-2. These results demonstrated that Fe/N/C is a promising candidate for ORR electrocatalyst in alkaline fuel cell.