Faradically Dominant Pseudocapacitive Manganese Cobalt Oxide Electrode Materials for Hybrid Supercapacitors and Electrochemical Water Splitting

Owing to their potential usage and great electrochemical performance, transition metal oxides (TMOs) are attracting enormous interest to be scrutinized for the energy-storage and conversion domain. Our work describes the electrochemical response of spinel transition metal oxides (Co3O4 and MnCo2O4) for electrochemical water splitting (oxidation evolution reaction (OER)) and hybrid energy-storage devices. After a comprehensive study of the structure and morphology, the synthesized materials were initially evaluated for the OER performance. Mn-doped Co3O4 performed better for OER due to the inclusion of Mn ions in the spinel structure. For the OER activity, the fabricated electrode showed an overpotential of 311 mV and a Tafel slope of 71 mV/dec upon obtaining the good performance of Mn-doped Co3O4 for OER; it was further utilized for energy-storage application by fabricating its hybrid supercapacitor device with activated carbon. The hybrid supercapacitor showed a better energy (36 W h/kg) and power density (4274 W/kg) relatively. Moreover, the semiempirical approach was adapted to further elaborate the experimental results obtained. The significant response of the developed electrodes enhances their potential for future energy-storage and conversion applications.