Electrochemical formation of copper phosphide from aqueous solutions of Cu(II) and hypophosphite ions

The electrochemical formation of copper phosphide phases on vitreous carbon electrodes from Cu(II) and hypophosphite acid aqueous solutions has been studied. It was found that the main component in the deposits was Cu, that their composition was independent of the electrodeposition potential, and that the P content increased with the proportion of hypophosphite with respect to Cu(II) in solution. Analysis of potentiostatic current transients recorded during deposition and the microscopic observation of the surface indicated that the mechanism of electrocrystallization occurs through copper electrodeposition, inducing the reduction of hypophosphite with concomitant formation of copper phosphide clusters followed by their aggregation, leading to the nucleation of three-dimensional centers with a growth rate controlled by the diffusion of electrodepositing species from the solution bulk, with generation also of byproducts of hypophosphite reduction. (C) 2020 Elsevier Ltd. All rights reserved.