Crystallinity engineering of FexO through doping and ligand design for improved oxygen Catalysis in Zinc-Air batteries

Abstract

The crystallinity of metal oxides plays a pivotal role in regulating the arrangement of metal atoms and thereby influencing electrocatalytic performance. This study focuses on carbon-supported transition metal oxide catalysts (V-Fe_xO/NC) and investigates how improved crystallinity impacts their performance in both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). It is demonstrated that doping with vanadium (V) and introducing nitrogen-containing ligands enhance the crystallinity of Fe_xO nanoparticles in the V-Fe_xO/NC catalyst. The high crystallinity of Fe_xO facilitates efficient electron transfer within the material and sequentially resulting in superior electrical conductivity. Furthermore, electron paramagnetic resonance (EPR) analysis suggests a lower concentration of oxygen vacancies in V-Fe_xO/NC sample, attributed to the well-ordered crystalline structure of Fe_xO, which minimizes internal defects and improves catalyst stability. As a result, the V-Fe_xO/NC composite demonstrates exceptional electrocatalytic efficiency, evidenced by a potential gap of merely 0.64 V, which surpasses the performance of the Pt/C + RuO₂ catalyst (0.66 V), while also exhibiting outstanding durability in both ORR and OER processes. Zinc-air batteries incorporated with V-Fe_xO/NC exhibit a stable open-circuit voltage (1.46 V) and high specific capacity (743.0 mAh g⁻¹).