Environment effects upon electrodeposition of thin film copper oxide nanomaterials

Abstract

Copper(I) oxide (Cu₂O) nanomaterials have become highly promising for photoelectrochemical reactions as both solar absorber layers in p–n heterojunction solar cells, direct photoelectrocatalysis and as electrodes in the CO₂ reduction reaction. Here we undertake a synthetic study towards the synthesis of Cu₂O nanocubes by utilising electrodeposition from copper salts (chloride, acetate, nitrate, and sulphate) in different solution environments. We initially set out to investigate the effect of electrolyte concentration on the growth of Cu₂O nanocubes. We also set out to mimic the high resistance inherent in the low electrolyte concentration environment by altering the distance between the electrodes. This deposition method was found to enable control of nanocube size formation. Both mixed anion environments and mono-anion environments were also investigated in a low-electrolyte concentration system. The fundamental physiochemical and electrochemical properties of each solution such as pH, conductivity, open circuit potential (V_OCP), solution resistance (R_S), and electron transfer resistance (R_ET) were measured. We then deposited copper oxide nanomaterials as thin films on ITO-coated glass substrates and assessed the electrical (conductivity) and optical (UV-Vis and E_g) properties of these films. Finally, we set out to investigate if any possible correlations could be drawn between the physiochemical and electrochemical properties of the solution and the electronic and optical properties of the deposited Cu₂O thin films.