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In this study, Fe2O3 photoelectrode thin films were grown on fluorine-doped tin oxide substrates at various temperatures ranging from 145 to 220 oC using modified chemical bath deposition. The morphological, structural, electrical, and photoelectrochemical properties of the resulting Fe2O3 photoelectrode were analyzed using field emission scanning electron microscopy, X-ray diffraction, electrochemical impedance spectroscopy, and a three-electrode potentiostat/galvanostat, respectively. Growth temperature and hydrochloric acid etching both affected the growth of the Fe2O3 photoelectrode, with Fe2O3 thin film thickness first increasing and then decreasing as growth temperature increased. The pH value of the precursor solution varied according to growth temperature, which in turn affected film thickness. The highest photocurrent density (0.53 mA/cm2 at 0.5 V vs. saturated calomel electrode) was obtained from the Fe2O3 photoelectrode grown at 190 oC, which yielded the thickest thin film, smallest full width at half maximum and largest grain size for the (104) and (110) plane, and highest flat-band potential value. Based on these findings, the photoelectrochemical properties of Fe2O3 photoelectrodes grown at various temperatures are strongly affected by their morphological, structural, and electrical properties.

In this study, we deposited a WO3 thin-film photoelectrode on a fluorine-doped tin oxide (FTO) substrate using a spin-coating method, and we investigated the photocurrent density and dark current density of the WO3 photoelectrode with various amounts of H2O2 additive. The morphological, structural, optical, electrical and photoelectrochemical properties of the WO3 photoelectrode with various amounts of H2O2 additive were analyzed using FE-SEM, XRD, UV-vis spectroscopy, EIS and a three-electrode potentiostat/galvanostat system, respectively. The amount of H2O2 additive has a large influence on the thickness of the WO3 photoelectrode, XRD (100) peak intensity, light absorption, optical energy bandgap, flat-band potential, donor density value, etc., and thus has a large influence on photoelectrochemical properties. Specifically, the H2O2 additive had a large influence on the growth of the WO3 photoelectrode, and the photocurrent density and dark current density characteristics of the WO3 photoelectrode grown to a uniform and thick thickness were largely improved. As a result, the WO3 photoelectrode fabricated with 0.2 mL of added H2O2 exhibited a high photocurrent density value of 1.17 mA/cm², which was about 23 times higher than that of the WO3 photoelectrode fabricated without H2O2 additive, and had a dark current density value of a low 0.04 mA/cm², which was a reduction of about 87%.

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