Fenvalerate is a common Pyrethroid insecticide exits stably in water and soil. This study subjected to enhance the degradation of fenvalerate (in the form of aqueous emulsion of a commercial formulation) using UV/ozone process. Experiment results indicated that fenvalerate was decomposed rapidly under UV irradiation (99% within 10 minutes). Degradation yield also showed an increase when ozone was applied. UV/ozone degradation rates of fenvalerate followed first-order kinetics. In alkaline medium, there was a slight increase in yield. Sodium nitrate acted as a photo-sensitizer for UV irradiation process so it helped to increase reaction rate at an optimum concentration of 2.5 mM. Moreover, some degradation products were identified and tentatively assigned by GC-MS.

This study deals with the preparation and characterization of platinum/reduced graphene oxide (Pt/rGO) as an efficient cathode for dye-sensitized solar cells. Herein, the Pt/rGO material was synthesized by co-precipitation from hexachloroplatinic acid (H 2 PtCl 6) and graphene oxide (GO) precursors. The fabrication of cathodes from Pt/rGO composite paste was carried out using screen-printing paste. The electrochemical behaviors of as-prepared cathodes were analyzed by cyclic voltammetry; the performance of fabricated DSSCs was measured by current density-voltage (J-V) curves and electrochemical impedance spectroscopy. The structural characteristics of the Pt/rGO binary composites were confirmed by Fourier-transform infrared spectroscopy, Raman spectroscopy, x-ray diffraction (XRD), and transmission electron microscopy. Empirical data showed that choosing ascorbic acid as a reducing agent at a ratio of 5:1 between ascorbic acid weight and precursor mixture weight, as well as a GO weight percentage of 20% fabricated DSSCs successfully with a conversion efficiency of 6.25%, which was approximately 90% compared to that of pure commercial Pt material. Characterization results indicated that the Pt nanoparticles were homogeneously distributed on the rGO sheets with an average diameter of less than 25 nm. The Pt/rGO hybrid composite is highly expected to replace Pt in the fabrication of cathodes in DSSCs for lowcost DSSC production in the promising future.

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