Effect of annealing on the electrodeposited Cu(2)O films for photoelectrochemical hydrogen generation

Abstract

Cu(2)O films were electrodeposited on stainless steel substrates followed by Ar annealing for photoelectrochemical hydrogen generation. Plating variables including time and pH for the plating bath were explored to obtain desirable film qualities. X-ray diffraction (XRD) patterns indicated that the as-deposited Cu(2)O films exhibited preferred orientations in (200) and (111) planes from the plating bath of pH 9 and pH 11, respectively. Images from scanning electron microscope (SEM) revealed pyramid-like grains in 1 mu m size for the Cu(2)O films from pH 9 plating bath and large plate-like grains in 3-8 mu m size from pH 11 plating bath. Identical results from SEM and XRD were obtained from the Cu(2)O films at longer plating time. After annealing at 350 degrees C for 30 and 60 min, the Cu(2)O phase was nicely maintained but SEM images demonstrated coarser grains. Photoelectrochemical activity for H(2) generation was obtained on the Cu(2)O films before and after annealing by recording relevant photoelectrochemical currents at -0.3 V in 0.5 M aqueous Na(2)SO(4) solution. For the Cu(2)O films from both baths, substantial increments in photoelectrochemical current were observed for the annealed samples as opposed to as-deposited ones. The largest photoelectrochemical current was obtained at 0.143 mA/cm(2) from the Cu(2)O film of pH 9 plating bath with 60 min annealing, which exhibited a 560% increase over the as-deposited sample. We attributed the enhanced photoelectrochemical current to the improved crystallinity and reduced defects for the annealed Cu(2)O films. (C) 2010 Elsevier B.V. All rights reserved.