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Reducing graphene dioxide (rGO) and titanium dioxide (TiO 2) composites with various rGO/TiO 2 ratios were prepared by hydrothermal method, in which rGO was synthesized from graphene powder according to modified Hummers method using microwave. Physico-chemical characteristics of the samples were investigated by the methods of N 2 adsorption-desorption measurements, X-ray diffraction, Raman, Fourier transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). rGO-TiO 2 (1:25) catalyst had smaller particle size and higher surface area than whose of pure TiO 2. Moreover, this modification also extended the region of photon absorption of TiO 2 towards the visible range of 397437 nm. The catalytic activity was investigated by photodegradation of cinnamic acid (CA) solution, which have been shown higher activity than that of the pure TiO 2 catalyst. The optimum conditions in this study for the degradation of CA were determined as follows: the ratio rGO/TiO 2 of 1:25, catalyst concentration of 0.75 g•L ¹1 , oxygen supply of 0.5 L•min ¹1 , initial pH solution of 3.8 and reaction temperature of 25°C. In this condition, cinnamic acid conversion in the solution reached approximately 90% after 60 minute reaction.

There are many options for reducing greenhouse gas emissions from energy systems while still meeting the global energy needs. One of the options could be renewable energy. Renewable energy has a huge potential to mitigate climate change, that can also provide people with utilities when using them. Renewable energy, if properly implemented, would contribute to socio-economic development, access to energy as a safe source of energy, and reduction of negative impacts on the environment and health. In the most demanding conditions, increasing the share of renewable energy in the energy mix will require policies to stimulate changes in the energy system. This research was focused on the solar photovoltaics (PV) system, especially on the interaction between wind and the PV system. The wind had a cooling effect to the PV system. The wind speed could greatly affect the operating performance of a PV system, especially in windy locations. In this paper, different velocity (from 3 to 15m/s) and incident angle of wind (from 0 to 180 degree) were used to carry out first the strength of PV system and then the influence of wind to the PV system by using ANSYS software. The PV system was found durable under these conditions. Velocity and direction of wind had strong effect to aerodynamic characteristics of solar panels.