Papers by Author: Laxmidhar Besra

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Authors: Mamiko Kawakita, Tetsuo Uchikoshi, Laxmidhar Besra, Tohru Suzuki, Jin Kawakita, Yoshio Sakka
Abstract: Crystal-oriented and crack-free thin TiO2 films with a good interfacial adhesion on indium-tin oxide (ITO) glass substrates for photoelectrodes were fabricated by the electrophoretic deposition (EPD) method in a 12 T strong magnetic field. A binder-free suspension for the EPD was prepared by dispersing TiO2 in the mixture of 2-propanol and 2,4-pentanedione. The electrophoretic mobility and the sedimentation rate were measured at various ratios of the mixed solution. The optimized state of the suspension exhibiting the highest surface charge potential and producing deposits with the highest green density was obtained at the 50:50 mixing ratio. The TiO2 films were characterized by XRD and SEM analyses. The photo-current measurement was also conducted to investigate the relation between the photo-anode characteristics of a dye-sensitized solar cell and the plane orientation of the TiO2 films
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Authors: Laxmidhar Besra, Tetsuo Uchikoshi, Tohru Suzuki, Yoshio Sakka
Abstract: Electrophoretic deposition (EPD) from aqueous suspension generally forms deposit containing incorporated bubbles because of evolution of gases at electrodes due to electrolysis of water. We have demonstrated here that application of pulsed voltage /current instead of continuous DC enables controlling the amount of bubble incorporation and obtain bubble-free deposits during EPD of aqueous suspension. The yield and bubble incorporation decreased progressively with decrease in size of the applied pulse. A characteristic band of deposition window was found in the plot of voltage/current vs. pulse width within which smooth and bubble-free deposits are obtained. The window is wider at low applied voltages/currents than at higher voltages/currents implying that it is more easier to control the pulsed EPD at lower applied voltages and/currents. No deposition occurred below the window whereas deposits with incorporated bubbles formed above the window. Suppression of bubbles with decreasing pulse size was attributed to decrease in the amount of hydrogen evolved per pulse and verified by monitoring the gain in weight of palladium (Pd) electrode used as cathode during electrolysis of water.
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