Increasing electrocatalytic efficiency of CuO/CoMn₂O₄ nanocomposite for oxygen evolution reaction

The development of sustainable energy conversion technologies accounts for the availability of efficient and abundant electrocatalysts for the oxygen evolution reaction (OER). These catalysts play a vital role in various energy conversion technologies, i.e., metal-air batteries, fuel cells, and water electrolysis. Therefore, it is necessary to identify and develop electrocatalysts that can perform the OER with high performance while being composed of abundant and inexpensive elements. In present work, we describe a straightforward method to produce a series of CuO/cobalt manganese oxide (CMO) spinal nanocomposites serving as an electrocatalyst for OER reactions. The CuO content can be easily changed to improve the activity of CuO-CMO_X (X = 12%, 16%, 20%) catalysts. The obtained results show that as compared to pure CMO spinel, the inclusion of CuO improved the OER activity, and CuO-CMO-16% of them demonstrated the best OER performance. The optimized electrocatalyst CuO-CMO-16% is characterized by different physical analyses. All electrochemical tests were performed via cyclic voltammetry (CV) and linear sweep voltammetry (LSV) techniques. This fabricated CuO-CMO-16% shows 277 mV overpotential at 10-mA cm⁻² current density which is smaller as compared to pristine CMO. Its higher conductivity is also indicated by smaller value of charge transfer resistance, obtained by Nyquist plot. The larger Co³⁺/Co²⁺ and Mn⁴⁺/Mn³⁺ ratio has a wider specific surface area of the CuO-CMO-16% catalyst improving the oxygen evolution due to exposed more active sites, which benefited the OER activity. The contact between both individuals can be simplified by the greater electrical conductivity, which considerably improved its OER capabilities.