Co-Doping-Assisted Systematic Evolution of a Truncated Octahedral from Tetrahedral Cu₂O for Enhanced Electrochemical OER Activity

For a sustainable future, electrocatalytic water splitting including two half-cell reactions is envisioned as an important alternative approach to replace fossil fuels. In this report, we have developed pure and cobalt (Co)-doped Cu 2 O-based electrocatalysts to investigate the effect of doping on different physicochemical characteristics and the OER activity of the Cu 2 O sample. During an investigation, a simple coprecipitation chemical approach was employed for the synthesis of pure and doped samples. Different mol % values of Co, including 2, 5, 7, and 10 mol %, were employed for the doping purpose. After successful synthesis, all of the samples were characterized using different techniques. The XRD analysis of the samples reveals the successful synthesis of highly pure monophasic Cu 2 O and Co-doped samples. The change in surface morphology and particle shape was analyzed using FESEM analysis, which revealed evolution from a pure octahedral shape of Cu 2 O to a truncated octahedral shape of the Co-doped Cu 2 O sample. In addition, TEM and HRTEM investigations also supported the SEM results, showing the successive transition of Cu 2 O particles. Further, surface properties were investigated using XPS analysis. All of the samples were investigated for OER application, and it was observed that with an increase in dopant concentration, the OER activity of the host sample increased significantly. The current density increased from 3.42 mA/cm 2 in pure Cu 2 O to 12.60 mA/cm 2 in a 10 mol % Co-doped Cu 2 O sample. Similarly, other parameters such as onset potential and Tafel slope demonstrated better catalytic performance of the 10 mol % Co-doped Cu 2 O sample. Finally, the stability of as-prepared electrodes for OER activity was investigated, and negligible loss in activity was observed after 200 CV cycles, thus confirming the high stability of developed catalysts.