We propose a solar cell design using the combination of titanium dioxide (TiO 2 ) and graphite as active photon absorbing materials. TiO 2 absorbs photons of nearly ultraviolet wavelengths to produce electron-hole pairs, while graphite is expected to absorb photons of longer wavelengths. Although many authors have claimed that graphite is a semimetal, we observed that a model of a solar cell containing TiO 2 only as the active material behaves exactly the same as a model containing graphite only as the active material. Additionally, we observed that a model of a solar cell made using a composite of TiO 2 and graphite as the active material had much higher efficiency than solar cells made using TiO 2 -or graphite-only active materials. Although the highest efficiency we report here is approximately 1 %, our proposed solar cell structure is promising for mass application, especially in low-income settings, owing to its easy and flexible fabrication, and easy largescale application.
Rice winnowing is a process of separation of small and large rice grains by air flow practiced since the ancient human history especially in societies where rice is the main source of carbohydrate (in Asia, Africa, and Latin America). Indeed, this process contains rich of scientific rule but has never been documented by the old society. We report here experimental investigation of the rice winnowing and develop a physical model to explain the process of segregation of rice grains having different size or density. Flapping the tray in the winnowing process, generates a vortex centered at position around the tray free end. We demonstrated numerically that the effectiveness of segregation is strongly depended on the different in grain sizes (for grain from the same material), the initial position of the grain, and the angular velocity of the vortex generated by flapping the tray. We obtained a phase diagram describing different final conditions of winnowing process (either the small grains move towards the tray fee end or move toward the inner end of the tray, able or unable to leave the tray at the free end). The result can be useful to design a new method in separating grains based on size or density.
The present work focused on the effects of TiO2 in degrading organic wastewater. Technical TiO2 of anatase crystalline phase was used. TiO2 photocatalyst showed a powerful result in destroying organic effluent. Spray coating was conducted to immobilize the TiO2 particles onto the plastic buffer followed with heat-treatment process. As a result, 30 mL of 25 mg L−1 methylene blue (MB) used in the photocatalyst test was sucessfully degraded after 4 hours of irradiation. Repetitive use of the TiO2 films still has a great photodecomposition ability of removing 99% of the organic contaminant after 5 times use.
In this study, we report well performance of Dye Sensitized Solar Cell (DSSC) coated with copper (Cu) by using the electroplating method. The Cu nanoparticle was impregnated into the pore of the titanium dioxide (TiO2) thin film. Particle contact between Cu and TiO2 plays important role to reduce the recombination effect of the electron and also lead to increase the electron transport in DSSC cell. Here, we used natural dye extracted from black rice and carbon from black ink as counter electrode. It is found that efficiency of DSSC coated with Cu nanoparticle is higher than pure DSSC which is obtained from I-V characterization. It shows that efficiency of DSSC is about 0.019% without coating Cu and enhanced about 0.105% after coating Cu. The analysis of internal resistance of DSSC was measured from Electrochemical Impedance Spectroscopy (EIS) characterization.
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