In alkaline media, Fe-N-C catalysts exhibit excellent oxygen reduction reaction (ORR) performance. In order to improve the intrinsic ORR activity of Fe-N-C catalysts, it is imperative to fine-tune the local coordination of FE sites to optimize the binding energy of ORR intermediates. Recently,Zhang Tierui, Technical Institute of Physics and Chemistry, Chinese Academy of ScienceswithGeoffrey I., University of Aucklandn. waterhouseA porous FeN4-O-NCR electrocatalyst was successfully synthesized, in which N-doped carbon nanorods (NCRs) were enriched with FeN4-O sites (in which Fe single atoms were coordinated with four in-plane nitrogen atoms and one subsurface axial oxygen atom).
The researchers first prepared O,N-co-doped carbon rods (O-NCR) and then anchored the Fe-N4 site on its surface with microwave-assisted pyrolysis, forming a stable Fe4-O-NCR heterostructure. The prepared FeN4-O-NCR has a hierarchical porous structure, a high specific surface area (1159 m2 g-1) and abundant FeN4-O active sites to optimize oxygen adsorption and activation. The advantages of FeN4-O-NC were calculated by theoretical density functional theory (DFT), and it was found that the thermodynamic barrier of ORR could be reduced by precise control of the electronic structure of the D orbital of Fe cations.
The FEN4-O-NCR catalyst exhibited significant ORR activity and stability in alkaline media (EONSET=1.).050v；e1/2=0.942v；0.JK is 39 at 9V56 ma cm-2)。Zinc-air cells constructed using FeN4-O-NCR as a cathode catalyst with a very high power density (2142 mW cm-2), significantly exceeding the commercial PT C catalyst (104.).2 mW cm-2) or other recently reported single-atom catalysts. In conclusion, axial ligand manipulation is an effective strategy for fine-tuning metal single-atom sites for optimal electrocatalytic activity.
mesopore-rich fe-n-c catalyst with fen4-o-nc single atom sites delivers remarkable oxygen reduction reaction performance in alkaline media. advanced materials, 2022. doi: 10.1002/adma.202202544