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Environmental pollution by organic dyes used in industry is a serious problem in developing countries. Environmentally friendly treatment methods are being studied because conventional methods require chemical or additional decomposition treatment. In particular, oxidation via a photocatalyst is a promising alternative due to its chemical and physical stabilities and low cost. However, electron-hole recombination limits the photocatalytic activity in semiconductor photocatalysts such as ZnO and TiO2. This study investigates control of electron-hole recombination of the photocatalyst by loading Au on ZnO (Au/ZnO). Using the Ultrasonic Spray Pyrolysis (USP) method, Au/ZnO particle generation is easily achieved under various conditions. XRD analysis confirms the crystal peaks of ZnO and Au. The EDX mapping and STEM images of the particles show that the Au crystals are well dispersed in the inner and outer portions of ZnO. The photocatalytic decomposition rate of organic dye (Rhodamine-B) is faster than that of ZnO in all Au/ZnO particles, and the best photocatalytic activity occurs in particles with 0.1 mass% Au supported on ZnO particles. In addition, optimal photolysis activity occurs in 100 mL of 5 mg/L RhB aqueous solution and 10 mg dose of Au/ZnO particles. (C) 2021 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

Polycrystalline copper sulphide (CuxS) thin films were grown by ultrasonic spray pyrolysis method using aqueous solutions of copper chloride and thiourea without any complexing agent at various substrate temperatures of 240, 280, and 320 degrees C. The films were characterized for their structural, optical, and electrical properties by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis of X-rays (EDAX), atomic force microscopy (AFM), contact angle (CA), optical absorption, and current-voltage (I-V) measurements. The XRD analysis showed that the films had single or mixed phase polycrystalline nature with a hexagonal covellite and cubic digenite structure. The crystalline phase of the films changed depending on the substrate temperature. The optical band gaps (E-g) of thin films were 2.07 eV (CuS), 2.50 eV (Cu1.765S), and 2.28 eV (Cu1.765S-Cu2S). AFM results indicated that the films had spherical nanosized particles well adhered to the substrate. Contact angle measurements showed that the thin films had hydrophobic nature. Hall effect measurements of all the deposited CuxS thin films demonstrated them to be of p-type conductivity, and the current-voltage (I-V) dark curves exhibited linear variation. Uludag UniversityUludag University [OUAP(F)-2013/11]; Uludag UniversityUludag University This work was supported by the Research Fund of Uludag University Project no. OUAP(F)-2013/11. The authors would like to thank Uludag University for financial support. The authors wish to thank Assoc. Professor Dr. Salih Kose of Osmangazi University (Turkey) for allowing the use of ultrasonic chemical spray pyrolysis system in semiconductor film production laboratory.

Tungsten oxide (WO₃) is prepared by a low-temperature ultrasonic spray pyrolysis method in air atmosphere, and it is used as an anode buffer layer (ABL) for organic solar cells (OSCs). The properties of the WO₃ transition metal oxide material as well as the mechanism of ultrasonic spray pyrolysis processes are investigated. The results show that the ultrasonic spray pyrolysized WO₃ ABL exhibits low roughness, matched energy level, and high conductivity, which results in high charge transport efficiency and suppressive recombination in OSCs. As a result, compared to the OSCs based on vacuum thermal evaporated WO₃, a higher power conversion efficiency of 3.63% is reached with low-temperature ultrasonic spray pyrolysized WO₃ ABL. Furthermore, the mostly spray-coated OSCs with large area was fabricated, which has a power conversion efficiency of ~1%. This work significantly enhances our understanding of the preparation and application of low temperature-processed WO₃, and highlights the potential of large area, all spray coated OSCs for sustainable commercial fabrication.