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Pure TiO2 and TiO2-CdS composite nanofibers were synthesized through electrospinning technique. The effects of various levels of CdS loading in a TiO2 nanofibers composite were investigated. Pure TiO2 nanofibers were polycrystalline with an anatase phase, whereas anatase and wurtzite phases coexisted in the TiO2-CdS composite nanofibers, according to X-ray diffraction (XRD) measurements. Using field emission scanning electron microscopy (FESEM) and UV-Visible spectroscopy, the impacts of composite CdS nanoparticles with TiO2 nanofibers were investigated. Pure TiO2 nanofibers have a smooth surface with several microns in length and 21–48 nm in diameter, but when CdS nanoparticles are added, the surface becomes granular. The energy band gap (Eg) evaluated from UV-Visible spectroscopy reduced from a value of 3.70 eV for pure TiO2 nanofibers to 1.70 eV for TiO2-1CdS nanofibers. Photocatalytic properties of pure TiO2 and TiO2-CdS composite nanofibers were calculated by a methylene blue (MB) aqueous solution degradation under sunlight irradiation. The results revealed that TiO2-0.5CdS nanofibers have efficient photocatalytic activity of up to 98 % after only 60 min.

This research presents a non-traditional method for surface modification. a Cu2O/CuO heterostructure was prepared on Cu foil by a dielectric barrier discharge (DBD) plasma and used as a photocathode for photoelectrochemical (PEC) water splitting. Cu2O/CuO heterostructure was prepared at 1 min, 3 min, and 6 min exposures of the Ar/O2 gas mixture using DBD plasma, followed by the calcination process at 200 °C for 2 hours. The samples were applied toward PEC water splitting. The samples' X-ray diffraction (XRD) pattern confirmed the cubic phase of Cu2O and the monoclinic phase of CuO. The field emission scanning electron microscope (FE-SEM) images show that the sample after 1 min of plasma exposure consists of a broccoli-like microstructure, and by increasing the duration time to 3 min and 6 min, the microwire structure was prepared. The presence of minuscule nanoparticles on the surface of all microstructures leads to an elevation in aspect ratio and charge carrier density, resulting in improved performance in photoelectrochemical (PEC) properties. The highest photocurrent of 6.53 mA/cm2 at 1.23 V vs. reversible hydrogen electrode (RHE) was recorded for Cu2O/CuO heterostructure prepared at 3 min exposure plasma under AM 1.5G irradiation. A longer exposure time of DBD plasma causes more thickness and increases the recombination of charge carriers, which decreases the photocurrent density to 4.32 mA/cm2 at 1.23 VRHE. This study demonstrates the development of a Cu2O/CuO heterostructure on Cu foil with a high aspect ratio as a promising method for enhancing the photoresponse of the Cu2O/CuO photocathode in the context of photoelectrochemical (PEC) water splitting. [ABSTRACT FROM AUTHOR]