A ZIF-derived hollow carbon nanoframework loaded with FeCu alloy nanoparticles for efficient oxygen reduction reaction and zinc-air batteries

Developing stable and porous oxygen reduction catalysts is crucial for advancing clean energy technologies. Zeolite imidazole frameworks (ZIFs) present versatile avenues for synthesizing non-noble metal ORR catalysts due to their unique morphology. While previous research has predominantly focused on augmenting catalytic properties through increased metal loading on ZIFs, herein we explore the engineering of ZIF-derived catalyst morphologies to enhance active site utilization and facilitate mass transport, presenting a promising avenue for performance improvement. We present a facile synthesis method for hollow carbon nano-frameworks (HCNFs) loaded with FeCu alloy nanoparticles, leveraging tannic acid assistance. The resulting FeCu-HCNFs exhibit a hierarchical pore structure, numerous defect sites, and enriched active sites on the shell, showcasing exceptional ORR activity. Specifically, the FeCu-HCNFs demonstrate a 25 mV higher half-wave potential compared to widely used noble Pt/C in alkaline systems and outstanding zinc-air battery performance. Density functional theory (DFT) results underscore the catalytic enhancement, revealing that introducing Cu increases the charge density at the central sites of Fe and reduces the adsorption energy for O2* and OH*. This morphological engineering strategy establishes FeCu-HCNFs as an effective Pt-free catalyst for the ORR, emphasizing its practical potential in advancing fuel cell technologies. Superior performance over Pt catalysts in oxygen reduction achieved by loading FeCu alloy nanoparticles through hollow carbon shells constructed from MOF materials.