Effect of Modification Method of TiO Nanotubes with CuO on Their Activity in Photoelectrochemical Water Splitting

TiO nanotube array electrodes for the photoelectrochemical process of water splitting were modified with CuO, -type semiconductor (-CuO). By employing the cyclic voltammetry (CV) method to deposit -CuO nanoparticles, a more uniform particle distribution was achieved over the inner and outer surfaces of TiO nanotubes. The measurements of incident photon-to-current conversion efficiency (IPCE) in the range of 365-660 nm demonstrated that the proposed method significantly enhance photoactivity in the visible light region compared to the potentiostatic deposition method. The IPCE value was 0.18% at a wavelength of 523 nm, which was 7 and 45 times higher than for the potentiostatic modified and pristine samples, respectively. Under continuous illumination with visible light at a wavelength of 523 nm and a potential of 0.2 V (Ag/AgCl (sat.)), the transition from CuO to CuO was observed for 5 hours, accompanied by a decrease in photocurrent density.