Tuning Band Gaps And Photoelectrochemical Properties Of Electrodeposited Cuo Films By Annealing In Different Atmospheres

The band gaps and photoelectrochemical properties of electrodeposited CuO films were tuned through annealing as-electrodeposited films in different atmospheres at various temperatures. The direct band gaps of the CuO film descended from 1.80 eV for as-electrodeposited film to 1.76 eV for the film annealed in O-2 at 300 degrees C or 1.64 eV for the film annealed in N-2 at 300 degrees C. The stable photocurrent density for CuO electrode annealed in O-2 at 300 degrees C measured at -0.4 V vs Ag/AgCl under a simulated sun light reached to 0.44 mA cm(-2) while the value was only 0.29 mA cm(-2) for the electrode annealed in N-2 in a solution with 10 mM potassium ferricyanide, 10 mM potassium ferrocyanide, and 0.5 M Na2SO4. The mechanism for photoresponse enhancement was studied and could be due to faster charge transfer and higher doping density for the CuO film annealed at 300 degrees C in O-2. (C) 2020 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited.