The copper interlayer tunes the reactivity of cobalt oxide towards the oxygen evolution reaction

Abstract

The activity of the cobalt-based material towards the oxygen evolution reaction can be enhanced via the metal interlayer. The metal interlayer, not only enhances the activity, it can also hamper the activity. The role of copper interlayer for activity changing depends on the fabrication method of the host material. In this study we have investigated the influence of Cu interlayering on the electrochemical properties of Co 3 O 4 nanoparticles. For this, we have initially synthesized the cobalt oxide nanoparticles employing the solution combustion method using cobalt nitrate and ascorbic acid as precursors. The ratio of cobalt nitrate and ascorbic acid plays a crucial role in determining the morphology and hence the electrochemical characteristics. Co 3 O 4 nanoparticles prepared with optimized amount of precursor (i.e., when ratio of cobalt nitrate and ascorbic acid is 1:1) showed the increased activity towards oxygen evolution reaction. While the samples prepared using lower/higher amounts of these precursors, showed the detriment in activity with copper interlayer. This effect is due to the presence of Co +3 at the surface. The polarization analysis showed that for optimized sample, the Co +3 content is highest while for high and low fuel content sample the Co +3 is low. The above analysis is further supported via the Tafel and electrochemical impedance analysis. The Tafel analysis showed the optimized sample showed the Tafel slope 100.26 mV/dec, while the high and low fuel content sample showed the 170.2 mV/dec and 219.72 mV/dec Tafel slope. Finally, the EIS analysis showed the lowest polarization resistance for optimized sample and high polarization resistance for high and low fuel content sample.