PHOTOELECTROCHEMICAL SEMICONDUCTOR SEPTUM (CDSE TI AND TIO2/TI) SOLAR-CELLS IN RELATION TO HYDROGEN-PRODUCTION/

Several finer details in the fabrication and working of photoelectroch emical (PEG) solar cells have been and are being mimicked from nature making PEC like the process of photosynthesis. A recent effort in this direction has been that of Tien and coworkers (1986), who have design ed a semiconductor-septum PEC solar cell after the working principle o f a thylakoid membrane in chloroplasts. Based on the theme of Tien et al., we have constructed semiconductor septum photoelectrochemical sol ar cells corresponding to configurations-GC/1M 3S//CdSe/Ti//aqueous el ectrolyte/GC and Pt/1M NaOH//TiO2/Ti//aqueous electrolyte/Pt. The sept um photoelectrodes are CdSe painted on a Ti sheet and anodically oxidi zed TiO2 on titanium. This cell is similar to that originally designed by Tien and coworkers. The dark compartment contains solutions of 1M K2SO4 + 5M H2SO4, 1M Na2SO4 + 5M H2SO4 and IM(NH4)(2)SO4 + 5M H2SO4. W hen CdSe/Ti and TiO2/Ti (septum photoelectrodes of light compartment) were illuminated with tungsten and xenon-mercury lamps, respectively, it leads to the evolution of hydrogen at the titanium surface in the d ark compartment without any externally applied voltage. The rate of hy drogen evolution has been found to be maximum under short circuit cond ition. Even though hydrogen production was invariably achieved, some a nomalous results have been obtained. It appears that hydrogen producti on in the dark compartment may be due to light-assisted reaction as we ll as some chemical reactions taking place in the dark compartment. Fu rther studies to optimize the conditions for solar-hydrogen production have been outlined.