Exploring discharged dry cell as an electrocatalyst for oxygen evolution reaction

Abstract

Transition metal compounds with a high affinity for oxygen in dry cell configurations, such as MnO2, Mn3O4, and ZnxMn3O4−x, exhibit exceptional electrocatalytic properties in the oxygen evolution reaction (OER). However, the disposal of these dry cell materials, unlike that of rechargeable batteries, poses environmental hazards. In this study, we focused on optimizing these manganese oxides for energy-related applications, specifically OER. To achieve this goal, we investigated the electrocatalytic behaviour of both used and fresh dry cells in OER. Our results show that the used dry cell material achieved a current density of 10 mA·cm−2 at an overpotential of 525 mV, whereas the fresh dry cell required an overpotential 100 mV higher to reach the same current density. We further characterized the nature of these fresh and used materials using various techniques, including x-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Raman spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), and contact angle measurements. The enhanced activity of the used dry cell can be attributed to the formation of highly active Mn3O4 from MnO2 and graphene oxide under discharging conditions.