Determination of critical conditions for the formation of electrodeposited copper structures suitable for electrodes in electrochemical devices

Abstract

Electrodeposition of copper from acid sulfate solutions at overpotentials on the plateau of the limiting diffusion current density and at higher overpotentials was examined. The average current efficiencies for hydrogen evolution reaction are determined by a measurement of the quantity of evolved hydrogen and the overall electrodeposition current as a function of electrodeposition time, while morphologies of copper deposits are examined by the use of the scanning electron microscopy (SEM) technique. It is found that the open and porous structures of copper deposits (denoted and as honeycomb - like copper structures), suitable for electrodes in electrochemical devices such as fuel cells and chemical sensors, were reached by electrodeposition processes from solutions with the lower concentrations of Cu (II) ions (0.15 M CuSO 4 and less in 0.50 M H2SO4) at overpotentials outside the plateau of the limiting diffusion current density at which the quantity of evolved hydrogen was enough to change hydrodynamic conditions in the near - electrode layer. The main characteristics of these copper structures were craters or holes formed primarily due to the attachment hydrogen bubbles with agglomerates of copper grains between them.