Improving the stability of copper oxide nanoparticles in photoelectrochemical water splitting

Abstract

In this work, the processing parameters of preparing dip coated CuO films which includes the withdrawal rate, film thickness and annealing temperature were optimized for photoelectrochemical (PEC) water splitting. The CuO samples were fabricated on fluorine-doped tin oxide (FTO) substrates at withdrawal rates of 50-200 mm/min, having films of 239.7-693.6 nm thicknesses, and annealed at 400-650 °C in air for 1 hour. Furthermore, the CuO films prepared at withdrawal speed of 150 mm/min, with thickness of 397.3 nm and annealed at 600 °C were modified with 1, 3, and 5 protective layers of activated charcoal (AC) silver (Ag), and gold (Au) nanoparticles (NPs) to improve their photo-stability in electrolyte. All the prepared CuO films were used as photocathodes in a three-electrode PEC device for water splitting. X-ray diffraction (XRD) and Raman spectroscopy studies confirmed the preparation of highly crystallized pristine CuO, CuO/AC, CuO/Ag and CuO/Au thin films. The surface morphology and cross-sectional view of the all thin films was investigated using the Field Emission Scanning Electron Microscope (FE-SEM). An energy dispersive X-ray spectroscopy (EDS) system was used to analyze the elemental composition of the thin films. XRD and RAMAN measurements was done to study the structural properties of thin films. The optical properties of the films was studied using a UV-Vis spectrometer. Lastly the thin films were used as photoelectrodes in a three-electrode electrochemical system to study their PEC properties. This study will be the pathway to forming stable photoelectrodes with enhanced photoelectrochemical efficiency for PEC water-splitting.