Reduced graphene aerogel anchored with MnCo2O4.5 spinel by self-assembly technique to boost bifunctional catalytic activity for zinc-air batteries

Abstract

Developing efficient and cost-effective bifunctional catalysts is pivotal in advancing Zn-air batteries (ZABs). In this study, a novel bifunctional cathode catalyst (A-rGO/MCO) is developed by anchoring needle-like MnCo₂O_4.5 (MCO) particles onto a self-assembled reduced graphene oxide aerogel. The A-rGO/MCO exhibits an ORR half-wave potential of 0.79 V (vs. RHE) and an OER potential of 1.68 V (vs. RHE) at a current density of 10 mA cm⁻². Specifically, recharge ZABs fabricated with A-rGO/MCO cathode catalyst displays excellent activity with a power density of as high as 152 mW/cm², a high discharge specific capacity of 815.1 mAh g⁻¹. Besides, A-rGO/MCO catalyst demonstrates excellent charge-discharge performance and stability in solid-state ZABs. The synergistic effect of graphene and MCO enhances the catalytic activity, electron transport and structural stability. The strong coupling between MCO and defect-rich reduced graphene aerogel can further increase the specific surface area, increase the active site, also regulate the electron configuration, introduce more defects, and thus improve the bifunctional electrocatalytic activity.