Fe nanoparticles confined by multiple-heteroatom-doped carbon frameworks for aqueous Zn-air battery driving CO₂...

Metal-organic frameworks (MOF) derived carbon materials are considered to be excellent conductive mass transfer substrates, and the large specific surface area provides a favorable platform for loading metal nanoparticles. Tuning the coordination of metals through polyacid doping to change the MOF structure and specific surface area is an advanced strategy for designing catalysts. Modification of Fe-doped ZIF-8 pre-curing by pyrolysis of phosphomolybdic acid hydrate (PMo), Fe nanoparticles confined by Mo and N co-doped carbon frameworks (Fe-NP/MNCF) were fabricated, and the impact of PMo doping on the shape and functionality of the catalysts was investigated. The Zn-air battery (ZAB) driven CO₂ electrolysis was realized by using Fe-NP/MNCF, which was used as bifunctional oxygen reduction reaction (ORR) and carbon dioxide reduction reaction (CO₂RR) catalysts. The results show that the half-wave potential (E_1/2) of Fe-NP/MNCF is 0.89 V, and the limiting diffused current density (j_L) is 6.4 mA cm^-2. The ZAB constructed by Fe-NP/MNCF shows a high specific capacity of 794.8 mAh g_Zn^-1, a high open-circuit voltage (OCV) of 1.475 V, and a high power density of 111.6 mW cm^-2. Fe-NP/MNCF exhibited efficient CO₂RR performance with high CO Faraday efficiency (FE_CO) of 87.5 % and current density for the generation of carbon dioxide (j_CO) of 10 mA cm^-2 at -0.9 V vs RHE. ZAB-driven CO₂RR had strong catalytic stability. These findings provide new methods and techniques for the preparation of advanced carbon-based catalysts from MOFs.