Fe-Co spinel oxides supported UiO-66-NH2 derived zirconia/ N-dopped porous hollow carbon as an efficient oxygen reduction reaction electrocatalyst

Abstract

The fuel cell is the best potential candidate to replace fossil fuels, which are a limited resource with severe environmental impacts that result in global warming and other more severe health issues. Developing a high-performing nonprecious electrocatalyst for oxygen reduction reaction (ORR) in the fuel cell is desirable but still a significant challenge. Herein, the uniform zirconia/N-dopped porous hollow carbon (ZrO2-N-C) with octahedral structure is derived from UiO-66-NH2 with not only abundant three-dimensional interconnected mesopores but also a high density of active sites. Zr-containing metal-organic framework is chosen due to the high stability and charge density, anti-toxicity, and small oxygen adsorption enthalpies of ZrO2 nanoparticles. The introduction of the SiO2 template during the synthesis of UiO-66-NH2 plays a crucial role in constructing controllable morphology, porosity, and components through the pyrolysis process. Furthermore, the synergic covalent coupling between metal oxide spinel (AB2O4) and nanocarbon effectively enhances the ORR catalytic activity. The substitution of an oxophilic metal (Fe) in Co3O4 spinel improves the electrocatalytic activity. The FeCo2O4/ES-ZrO2/NC catalyst exhibits a high catalytic activity toward ORR with an Eonset of − 0.18 V vs Ag/AgCl with a Fe/Co ratio of 3:1 in an alkaline electrolyte. The as-prepared FeCo2O4/NC exhibits not only high electrocatalytic activity but also good stability better than the Pt/C catalyst. The porosity, various valances of metals, high surface area, and N-doped C active sites are considered the main reasons for ORR's high catalytic activity.