Electrochemical Nanostructuring of Electrodeposited Cu2o Thin Film for Efficient Hydrogen Reduction

Abstract

Cu2O is an intrinsic p-type semiconductor with a direct bandgap of 2 eV and its conduction band edge lies 0.7 V negative of hydrogen reduction potential which makes it a promising photocathode for water splitting. This study emphasizes the modification of the surface of Cu2O thin films to facilitate the separation of photogenerated charge carriers as well as increase the electrode-electrolyte contact area. Mesoporous Cu2O is realized by holding a thin film of electrodeposited Cu2O at a positive potential (0.4 V ‒ 1 V vs. Ag/AgCl) in buffered Na2SO4 (pH 5) . The treated films are found to have mesoporous structure with 10-30 nm thick flakes on its surface. No phase change is observed in electrochemically treated Cu2O thin films although the XRD intensities of all peaks are slightly lower indicating material loss. This morphological conversion is attributed to Cu2O dissolution in acidic media as trace copper ions are detected in the solution. The modified Cu2O photocathode can lead to a better device performance due to increased surface area and improved charge transport. Figure 1