Synthesis and characterization of nanoporous ZnO and Pt/ZnO thin films for dye degradation and water splitting applications

In this paper, nanoporous ZnO and Pt/ZnO films were synthesized by a combination of simple spray pyrolysis and DC sputtering techniques at different flow rates and deposition times. X-ray diffraction, contact angle, and spectrophotometric measurements showed the growth of hexagonal ZnO Wurtzite phase with hydrophilic nature and high transparency in the visible region. By sputtering Pt nanoparticles on ZnO surfaces, the absorption edge is redshifted from UV region to the visible light region. The optical band gap of Pt/ZnO films is decreased from 3.74 to 1.86 eV as the deposition time increased to 4 min. The Pt/ZnO films exhibited higher photocatalytic activity and stability than pure ZnO films for methylene blue photodegradation. From the photoelectrochemical water splitting measurements, the current density of 4 min Pt/ZnO film is one hundred times greater than the value of pure ZnO film. The incident photon-to-current conversion efficiency at 470 nm was for the first time 76.2%. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.