Zinc-Mediated Template Synthesis of Fe-N-C Electrocatalysts with Densely Accessible Fe-Nx Active Sites for Efficient Oxygen Reduction.
Owing to their earth abundance, high atom utilization, and excellent activity, single iron atoms dispersed on nitrogen-doped carbons (Fe-N-C) have emerged as appealing alternatives to noble-metal platinum (Pt) for catalyzing the oxygen reduction reaction (ORR). However, the ORR activity of current Fe-N-C is seriously limited by the low density and inferior exposure of active Fe-Nx species. Here, a novel zinc-mediated template synthesis strategy is demonstrated for constructing densely exposed Fe-Nx moieties on hierarchically porous carbon (SA-Fe-NHPC). During the thermal treatment of 2,6-diaminopyridine/ZnFe/SiO2 complex, the zinc prevents the formation of iron carbide nanoparticles and the SiO2 template promotes the generation of hierarchically pores for substantially improving the accessibility of Fe-Nx moieties after subsequent leaching. As a result, the SA-Fe-NHPC electrocatalysts exhibit an unprecedentedly high ORR activity with a half-wave potential (E1/2 ) of 0.93 V in a 0.1 m KOH aqueous solution, which outperforms those for Pt/C catalyst and state-of-the-art noble metal-free electrocatalysts. As the air electrode in zinc-air batteries, the SA-Fe-NHPC demonstrates a large peak power density of 266.4 mW cm-2 and superior long-term stability. Therefore, the developed zinc-mediated template synthesis strategy for boosting the density and accessibility of Fe-Nx species paves a new avenue toward high-performance ORR electrocatalysts.
['Chen|Guangbo|G|https://orcid.org/0000-0003-1927-3642', 'Liu|Pan|P|', 'Liao|Zhongquan|Z|', 'Sun|Fanfei|F|', 'He|Yanghua|Y|', 'Zhong|Haixia|H|', 'Zhang|Tao|T|', 'Zschech|Ehrenfried|E|', 'Chen|Mingwei|M|', 'Wu|Gang|G|', 'Zhang|Jian|J|', 'Feng|Xinliang|X|']
oxygen reduction reaction Fe-N-C catalysts Zn-air batteries accessible active sites zinc-mediated synthesis