Photoelectrochemical Properties of Copper Oxide Photoelectrode with Various Copper Oxide Buffer Layers

Abstract

In this study, a CuO buffer layer was deposited on a fluorine-doped tin oxide (FTO) substrate using a spin coating method, and then a CuO photoelectrode was grown on the CuO buffer layer using a modifiedchemical bath deposition (M-CBD) method. We investigated the morphological, structural, optical, electrical and photoelectrochemical properties of the CuO photoelectrode grown according to the number of deposited CuO buffer layers, using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), UVvisible spectroscopy (UV-vis), electrochemical impedance spectroscopy (EIS) and three-electrode potentiostat, respectively. From the study, we found that the root mean square (RMS), surface area, optical energy bandgap, flat-band potential, acceptor density, and photoelectrochemical properties of the CuO photoelectrode were greatly influenced by changes in the CuO buffer layer, depending on the number of deposited buffer layers. It was also found that growth in the (11) and (111) direction planes of the CuO photoelectrode affected the sheetshape structural growth of the CuO photoelectrode. In addition, it was observed that the CuO photoelectrode using the CuO buffer layer grew uniformly and nano-sized. As a result, the highest photocurrent density value of-2.22 mA/cm 2 (at-0.55 V vs. SCE) was obtained from the CuO photoelectrode fabricated with 3 cycles of CuO buffer layer deposition. It was the thickest, had the lowest optical energy band gap, the highest RMS value, surface area, preferential growth on the (11) plane, flat-band potential and acceptor density.