We report the development of graphite-based solar cells using a simple method and low cost materi... more We report the development of graphite-based solar cells using a simple method and low cost materials. Suspension of graphite powder in mineral water was simply dropped onto the surface of fluorine-doped tin oxide glass (FTO) to form a thick film. Surprisingly, using mineral waters greatly improved the efficiency of the solar cell to reach the highest efficiency of 6.97%. Due to some minerals contained, the mineral water induced the development of fibrous structure between the graphite particles which is assumed to play a role as a bridge for the photoexcited electrons to quickly move to the electrode and suppress recombination with holes. This efficiency is very attractive when considering the materials used to develop the solar cell are all low cost. Economically this may challenge the present high efficiency semiconductor-based solar cells. We achieved the high efficiency by manipulating the cell fill factor through optimizing the ion concentration in PVA.LiOH polymer electrolyte....
In some countries, cars and motorbikes are allowed to pass through the same road. We observe a ph... more In some countries, cars and motorbikes are allowed to pass through the same road. We observe a phenomenon similar to a Brazil nut effect (BNE) that frequently occurs on such roads, in which motorbikes (representations of small particles) segregate in front of cars (representations of large particles), although the motorbikes are initially located far behind the cars. Deep investigations of the BNE-like phenomena in such roads are reported here, where a combination of aerial views using a quad-copter camera and simulations is studied. We show for the first time that most phenomena observed in common BNEs are also observed in such roads.
Rice winnowing is a process of separation of small and large rice grains by air flow practiced si... more 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 gr...
The efforts to fabricate a solar cell cheaper than DSSC type have been increasingly developed. A ... more The efforts to fabricate a solar cell cheaper than DSSC type have been increasingly developed. A new design of solar cell using cheap TiO2 as photon absorber and PVA.LiOH as hole transport medium has been continously evolved, including the attempt to alter LiOH as main material of polymer electrolyte. For this purpose, an inexpensive solar cell using PVA.NaCl polymer electrolyte as a hole transport medium replacing PVA.LiOH has been successfully fabricated. A suspension of TiO2 was initially deposited on Fluorine Tin Oxide using droplet method followed by heating at 200 °C for two hours. The content of NaCl was varied from 10, 21, 32 and 43% compared to the content of PVA to achieve the best efficiency. 0.04% efficiency was gained using 32% of NaCl content. To get a better performance of the solar cell, TiO2/graphite composite was used as photon absorbing materials. Graphite powder was inserted into the suspension of TiO2 and varied from 10, 20, 30 and 40% based on the TiO2 content....
IOP Conference Series: Materials Science and Engineering, 2020
Solar cell using TiO2/coffee composite as photon absorbing material has been successfully fabrica... more Solar cell using TiO2/coffee composite as photon absorbing material has been successfully fabricated. A suspension of TiO2/coffee was dropped on Fluorine Tin Oxide substrate which was previously heated on a hotplate with temperature of 100 °C. The fraction of coffee was varied from 10, 20, 30, 40, and 50 %, compared to the mass of TiO2. PVA-LiOH electrolyte polymer was functionalized as the hole transport medium. The highest efficiency of 0.76 % was achieved with 40% of coffee fraction. The solar cell is promising to be developed in the future due to the easy method and cheap materials used.
IOP Conference Series: Materials Science and Engineering, 2019
We have successfully fabricated solar cell using flexible counter electrode of graphite powder. T... more We have successfully fabricated solar cell using flexible counter electrode of graphite powder. TiO2 / graphite suspension was simply poured onto heated Fluorine Tin Oxide (FTO) substrate and kept heated at 200°C for 2 hours. PVA.LiOH polymer electrolyte was employed as a positive charge transfer medium. The counter electrode was made of graphite powder which is manually deposited on transparent plastic using tube-shaped metal which its surface covered with tissue of 2 mm thick. Graphite powder was deposited by straight motion of 20 movements for one coating or one layer. The same activity was repeated on the stacked film to increase the conductivity of the film. Resistivity and transmittance measurement of the film was performed by four-point probe method and UV-Vis equipment respectively. The film thickness and 2-D porosity were measured using an electronic microscope and ImageJ software orderly. The film resistivity and transmittance gradually decreased with the increase of coati...
IOP Conference Series: Materials Science and Engineering, 2019
The present work focused on the effects of TiO2 in degrading organic wastewater. Technical TiO2 o... more 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.
IOP Conference Series: Materials Science and Engineering, 2019
Indonesia has great potential of the Solar energy, irradiated by the Sun throughout the years. Co... more Indonesia has great potential of the Solar energy, irradiated by the Sun throughout the years. Cotton textiles antibacterial has been prepared by coating Titania (TiO2) with Polyethylene glycol (PEG) and Polyvinyl alcohol (PVA) as adhesives. The method of depositing cotton using a simple dip coating. Cotton dry for 15 minutes with a halogen lamp, after the deposition process. Then, we do the antibacterial activity test using Plate Count Method. As a result, the coated cotton textiles with Polyvinyl alcohol (PVA), Polyethylene glycol (PEG) has antibacterial properties. Characterization by the Attenuated Total Reflectance (ATR) obtained that Titania (TiO2) surely adhere on the sample. From Attenuated Total Reflectance (ATR) characterization we conclude that Polyvinyl alcohol (PVA) and Polyethylene glycol (PEG) is not affecting the antibacterial ability of Titania (TiO2). But the infusion of Polyvinyl alcohol (PVA) and Polyethylene glycol (PEG) on Cotton increases the stiffness value o...
A preliminary study has been performed on the analysis of the stability of predator-prey models i... more A preliminary study has been performed on the analysis of the stability of predator-prey models in the case of aerosol-cloud-precipitation interactions which initiated by Koren-Feingold. The model consists of two coupled non-linear differential equations describing the development of a population of cloud drop concentration and cloud depth for precipitation. Stability analysis of the models was conducted to understand the stability behavior of systems interactions. In this paper, the analysis focused on the model without delay. The first step was done by determining the equilibrium point of the model equations which yielded 1 non-trivial equilibrium point and 4 trivial equilibrium point. Nontrivial equilibrium point (0,0) associated with the steady state or the absence of precipitation while the non-trivial equilibrium point shows the oscillation behavior in the formation of precipitation. The next step is linearizing the equation around the equilibrium point and calculating of eigenvalues of Jacobian matrix. Evaluation of the eigen values of characteristic equation determined the type of stability. There are saddle node, star point, unstable node, stable node and center. The results of numerical computations was simulated in the form of phase portrait to support the theoretical calculation. Phase portraits show the characteristic of populations growth of cloud depth and drop cloud. In the next research, this analysis will compared to delay model to determine the effect of time delay on the equilibrium point of the system.
In this study, we report well performance of Dye Sensitized Solar Cell (DSSC) coated with copper ... more 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.
We report the development of graphite-based solar cells using a simple method and low cost materi... more We report the development of graphite-based solar cells using a simple method and low cost materials. Suspension of graphite powder in mineral water was simply dropped onto the surface of fluorine-doped tin oxide glass (FTO) to form a thick film. Surprisingly, using mineral waters greatly improved the efficiency of the solar cell to reach the highest efficiency of 6.97%. Due to some minerals contained, the mineral water induced the development of fibrous structure between the graphite particles which is assumed to play a role as a bridge for the photoexcited electrons to quickly move to the electrode and suppress recombination with holes. This efficiency is very attractive when considering the materials used to develop the solar cell are all low cost. Economically this may challenge the present high efficiency semiconductor-based solar cells. We achieved the high efficiency by manipulating the cell fill factor through optimizing the ion concentration in PVA.LiOH polymer electrolyte....
In some countries, cars and motorbikes are allowed to pass through the same road. We observe a ph... more In some countries, cars and motorbikes are allowed to pass through the same road. We observe a phenomenon similar to a Brazil nut effect (BNE) that frequently occurs on such roads, in which motorbikes (representations of small particles) segregate in front of cars (representations of large particles), although the motorbikes are initially located far behind the cars. Deep investigations of the BNE-like phenomena in such roads are reported here, where a combination of aerial views using a quad-copter camera and simulations is studied. We show for the first time that most phenomena observed in common BNEs are also observed in such roads.
Rice winnowing is a process of separation of small and large rice grains by air flow practiced si... more 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 gr...
The efforts to fabricate a solar cell cheaper than DSSC type have been increasingly developed. A ... more The efforts to fabricate a solar cell cheaper than DSSC type have been increasingly developed. A new design of solar cell using cheap TiO2 as photon absorber and PVA.LiOH as hole transport medium has been continously evolved, including the attempt to alter LiOH as main material of polymer electrolyte. For this purpose, an inexpensive solar cell using PVA.NaCl polymer electrolyte as a hole transport medium replacing PVA.LiOH has been successfully fabricated. A suspension of TiO2 was initially deposited on Fluorine Tin Oxide using droplet method followed by heating at 200 °C for two hours. The content of NaCl was varied from 10, 21, 32 and 43% compared to the content of PVA to achieve the best efficiency. 0.04% efficiency was gained using 32% of NaCl content. To get a better performance of the solar cell, TiO2/graphite composite was used as photon absorbing materials. Graphite powder was inserted into the suspension of TiO2 and varied from 10, 20, 30 and 40% based on the TiO2 content....
IOP Conference Series: Materials Science and Engineering, 2020
Solar cell using TiO2/coffee composite as photon absorbing material has been successfully fabrica... more Solar cell using TiO2/coffee composite as photon absorbing material has been successfully fabricated. A suspension of TiO2/coffee was dropped on Fluorine Tin Oxide substrate which was previously heated on a hotplate with temperature of 100 °C. The fraction of coffee was varied from 10, 20, 30, 40, and 50 %, compared to the mass of TiO2. PVA-LiOH electrolyte polymer was functionalized as the hole transport medium. The highest efficiency of 0.76 % was achieved with 40% of coffee fraction. The solar cell is promising to be developed in the future due to the easy method and cheap materials used.
IOP Conference Series: Materials Science and Engineering, 2019
We have successfully fabricated solar cell using flexible counter electrode of graphite powder. T... more We have successfully fabricated solar cell using flexible counter electrode of graphite powder. TiO2 / graphite suspension was simply poured onto heated Fluorine Tin Oxide (FTO) substrate and kept heated at 200°C for 2 hours. PVA.LiOH polymer electrolyte was employed as a positive charge transfer medium. The counter electrode was made of graphite powder which is manually deposited on transparent plastic using tube-shaped metal which its surface covered with tissue of 2 mm thick. Graphite powder was deposited by straight motion of 20 movements for one coating or one layer. The same activity was repeated on the stacked film to increase the conductivity of the film. Resistivity and transmittance measurement of the film was performed by four-point probe method and UV-Vis equipment respectively. The film thickness and 2-D porosity were measured using an electronic microscope and ImageJ software orderly. The film resistivity and transmittance gradually decreased with the increase of coati...
IOP Conference Series: Materials Science and Engineering, 2019
The present work focused on the effects of TiO2 in degrading organic wastewater. Technical TiO2 o... more 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.
IOP Conference Series: Materials Science and Engineering, 2019
Indonesia has great potential of the Solar energy, irradiated by the Sun throughout the years. Co... more Indonesia has great potential of the Solar energy, irradiated by the Sun throughout the years. Cotton textiles antibacterial has been prepared by coating Titania (TiO2) with Polyethylene glycol (PEG) and Polyvinyl alcohol (PVA) as adhesives. The method of depositing cotton using a simple dip coating. Cotton dry for 15 minutes with a halogen lamp, after the deposition process. Then, we do the antibacterial activity test using Plate Count Method. As a result, the coated cotton textiles with Polyvinyl alcohol (PVA), Polyethylene glycol (PEG) has antibacterial properties. Characterization by the Attenuated Total Reflectance (ATR) obtained that Titania (TiO2) surely adhere on the sample. From Attenuated Total Reflectance (ATR) characterization we conclude that Polyvinyl alcohol (PVA) and Polyethylene glycol (PEG) is not affecting the antibacterial ability of Titania (TiO2). But the infusion of Polyvinyl alcohol (PVA) and Polyethylene glycol (PEG) on Cotton increases the stiffness value o...
A preliminary study has been performed on the analysis of the stability of predator-prey models i... more A preliminary study has been performed on the analysis of the stability of predator-prey models in the case of aerosol-cloud-precipitation interactions which initiated by Koren-Feingold. The model consists of two coupled non-linear differential equations describing the development of a population of cloud drop concentration and cloud depth for precipitation. Stability analysis of the models was conducted to understand the stability behavior of systems interactions. In this paper, the analysis focused on the model without delay. The first step was done by determining the equilibrium point of the model equations which yielded 1 non-trivial equilibrium point and 4 trivial equilibrium point. Nontrivial equilibrium point (0,0) associated with the steady state or the absence of precipitation while the non-trivial equilibrium point shows the oscillation behavior in the formation of precipitation. The next step is linearizing the equation around the equilibrium point and calculating of eigenvalues of Jacobian matrix. Evaluation of the eigen values of characteristic equation determined the type of stability. There are saddle node, star point, unstable node, stable node and center. The results of numerical computations was simulated in the form of phase portrait to support the theoretical calculation. Phase portraits show the characteristic of populations growth of cloud depth and drop cloud. In the next research, this analysis will compared to delay model to determine the effect of time delay on the equilibrium point of the system.
In this study, we report well performance of Dye Sensitized Solar Cell (DSSC) coated with copper ... more 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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