Green synthesis of Cu/Cu2O/CuO nanostructures and the analysis of their electrochemical properties

Heterogeneous Cu/Cu2O/CuO nanoparticles were synthesised via polyphenols of pomegranate for various application. X-ray diffraction and high resolution-scanning electron microscopy confirmed Cu/Cu2O/CuO NPs crystallinity and the particle size which ranged from 5 to 20 nm. The electrochemical band gap energies of Cu/Cu2O/CuO NPs were calculated to be between 0.9 and 2.1 eV. EIS measurements were used to calculate the capacitance and specific capacitance of the nanoparticles which were found to be 11.2 F and 69 F g(-1). Surface diffusion coefficient obtained from cyclic voltammetry was found to be 1.54 x 10(-6) cm(2) s(-1) with r(2) of 0.99 suggesting a fast electron movement. The calculated surface coverage was 1.38 x 10(-3) mol cm(-2) suggesting the formation of monolayer at the electrode interface. The results confirmed the electroactivity of Cu/Cu2O/CuO electrode towards the volatile organic compound- ethanol. Cu/Cu2O/CuO exhibited good electrochemical performance towards ethanol with higher current density and most negative onset potential - 0.3 V, meaning that it requires lower energy for ethanol activity to occur at the electrode interface. EIS profiles confirmed the kinetics of Cu/Cu2O/CuO at the electrode surface with characteristic small circular curvature signifying that the polarisation resistance (Rp) is prominent, proposing a faster electron shuttling process for ethanol activity. Further, the amperometric response with long time test for the Cu/Cu2O/CuO based electrode system estimated a lower limit of detection to be 0.09 mu M at a signal to noise ratio of 3 with sensitivity of 0.049 mu A mu M-1 at steady state. Raman and FTIR highlighted mechanism of coordination.