Optimization of hydrogen production by water electrolysis

Abstract

Recently, hydrogen has been considered as a future energy carrier. Hydrogen is believed to be the most important long-term option for addressing the energy, environmental and economic concerns since it is a renewable and clean energy resource. The simplest and cheapest way to produce hydrogen is by electrolysis. However, the process is inefficient. Therefore the objective of this study is to enhance the hydrogen production by optimizing the electrolysis parameters as well as the laser parameters. In this study, fixed volume of distilled water was employed as medium and sodium chloride used as catalyst. Graphite rods were used as electrodes which were supplied by varying voltage. Molybdenum sheets with various surface areas were utilized as a sacrifice agent to protect the cathode. Meanwhile, ethanol solution was used to compensate oxidation by donating an amount of electron in the electrolyte was deployed as supplement. Hence the electrolyte parameters were optimized by varying the voltage, the sacrifice agents and electron donor. In addition, the hydrogen production was also enhanced by illuminating light into the electrolysis chamber. The light source was also optimized by varying the wavelength and the power of the light. In this study, the light source used comprised of diode-pumped solid state laser at various wavelength including, 485 nm, 532 nm, 635 nm, while nitrogen laser and conventional UV light source were at 337 nm and 403 nm respectively. The results obtained showed that the hydrogen increased with the voltage as well as the sacrifice agent area. The larger the voltage, the more the water splitting and the larger the area of sacrifice agent, the more protection on the cathode. Thus, more hydrogen production was encouraged. In contrast, the addition of the supplementary element ethanol was limited to 7 mL and above 7 mL, it resisted the hydrogen production. In the case of illumination light, green laser at 532 nm had shown a pronounced result. This was due to the light that is transparent to the water, thus contributing to more electric field into the electrolysis system. Furthermore, the higher the power of the green laser into the electrolysis chamber the more hydrogen production was realized. Thus, the effectiveness as well as the efficiency of the hydrogen production do relies on the optimizing parameters.