Fabrication of strong bifunctional electrocatalytically active hybrid Cu-Cu2O nanoparticles in a carbon matrix

Herein, earth-abundant cost-effective hybrid copper-cuprous oxide nanoparticles have been fabricated in a carbonmatrix (Cu-Cu(2)ONPs@C) and used as bifunctional electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). At a 0.1 mg loading, OER studies of Cu-Cu(2)ONPs@C showed a significantly low overpotential of 530 mV@10 mA cm(-2) with the applied potential of 2.07 V in 0.4 M KOH. HER studies showed an overpotential of -672 mV@10 mA cm(-2) with the applied potential of -1.058 V in 0.4 M H2SO4. Cu-Cu(2)ONPs@C showed a good electrocatalytic current density of 57.7 mA cm(-2) for OER and -125 mA cm(-2) for HER at a significantly low catalyst loading. For controlled studies, Cu(2)ONPs and CuNPs in carbon matrix have also been synthesized, and their catalytic activities (OER and HER) have been compared with those of the hybrid Cu-Cu(2)ONPs@C. The comparative studies indicated that the presence of conducting metal CuNPs along with Cu(2)ONPs in the carbon matrix enhanced the electrocatalytic activity for both OER and HER as compared to that of pure Cu(2)ONPs and CuNPs in the carbon matrix. Interestingly, the solvent used for fabricating different NP electrodes has also shown significant influence on the electrocatalytic current density. The synthesized hybrid Cu-Cu(2)ONPs@C, Cu(2)ONPs@C, and CuNPs@C were characterized using powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HR-TEM), and BET analysis. To the best of our knowledge, the fabricated hybrid Cu-Cu2ONP@C exhibited a strong bifunctional electrocatalytic response at a high current density with a low catalyst loading (0.1 mg) among the different Cu-based nanostructured catalysts explored for the water splitting reactions.