Lilac flower-shaped ZnCo2O4 electrocatalyst for efficient methanol oxidation and oxygen reduction reactions in an alkaline medium

Abstract

The oxygen reduction reaction (ORR) plays a vital role in electrochemical energy conversion and energy storage devices such as metal–air batteries and alkaline fuel cells. The development of proficient, noble metal-free catalysts for electrocatalytic ORRs is one of the main challenges impeding fuel cell research. ZnCo₂O₄ lilac flowers (LFs) were synthesized using a rapid microwave irradiation method, at 160 °C for 15 min, followed by annealing, at 400 °C for 4 h. XRD confirms their high crystallinity and phase purity. HR-TEM images show several smaller, primary nanoparticle building blocks, which combine to form lilac flower-like structures, through a self-assembly process. The methanol oxidation reaction (MOR) and ORR were evaluated using ZnCo₂O₄ LFs as a catalyst. The stability and durability of the ZnCo₂O₄ LF catalyst were analyzed by chronoamperometry (CA) measurements and CA responses for the ORR on ZnCo₂O₄ LFs at −0.5 V vs. RHE, in O₂-saturated 0.1 M KOH electrolyte. These tests showed that the catalyst exhibited remarkable MOR and ORR activity in alkaline media.