In situ electrochemical quartz crystal microbalance study of potential oscillations during the electrodeposition of Cu/Cu2O layered nanostructures

Application of a constant cathodic current to an electrode in an alkaline C u(II) lactate solution results in oscillation of the electrode potential du ring the electrodeposition of copper/cuprous oxide layered nanostructures. The electrochemical quartz crystal microbalance (EQCM) is used for in situ phase analysis measurements of the nanoscale layers and the results are com pared with bulk XRD measurements. The EQCM is also used to estimate the lay er thicknesses and overall modulation wavelength of the nanostructures. We propose that Cu2O is deposited during the positive spikes in electrode pote ntial, while a composite of Cu and Cu2O is deposited during the more negati ve plateau region of the oscillation. The modulation wavelength calculated from the EQCM is in good agreement with that observed with scanning electro n microscopy. The EQCM is shown to be a useful tool for estimating layer th icknesses and phase compositions for layers that are too thin to be examine d by other instrumental techniques.