Photogalvanics of Aluminum Metal and Aluminum Alloy Working Electrodes for Solar Power Generation with Dual Modes of Storage

The photogalvanic cells are based on photochemical processes that give rise to high-energy species (i.e., semi- and leuco-reduced forms of the sensitizer molecule) on excitation by a photon. These energy-rich species form the basis of power generation and storage in photogalvanic cells. In photogalvanic cells, chemical reactions usually occur efficiently in an alkaline electrolyte. The alkaline medium in photogalvanic cells plays a crucial role in facilitating the redox reactions necessary for energy conversion processes. The main aim of the present research is to investigate the photogalvanics of alternate novel working electrode materials, like Al and its alloys, in place of the traditionally used Pt working electrode, and to study their electrochemical properties in an alkaline medium. But, it has been observed that electrode materials like Al and its alloys are consumed with hydrogen evolution in alkaline solutions. Traditionally reported photogalvanic cells have mainly focused on solar power storage chemically in the form of energy-rich semi- or leuco-reduced dye species. But, in the present research, the evolution of hydrogen provides an additional mode of storage of solar power in chemical form through photogalvanic cells. In this study, the photogalvanic system comprising an Al metal working electrode, Allura Red dye photosensitizer, d-Galactose reductant, Didecyldimethylammonium Chloride (DDAC) surfactant, and NaOH alkali has been investigated. A power of 2525.7 μW and a conversion efficiency of 17.65 % have been obtained for the small-sized Al electrode (0.2 cm × 0.3 cm). For a large-sized Al electrode (1.0 cm × 1.0 cm), the obtained power and efficiency were 2392.3 μW and 1.91 %, respectively. For the photogalvanic system comprising an Al alloy as the working electrode, Allura Red dye as the photosensitizer, d-Galactose as the reductant, DDAC as the surfactant, and NaOH as the alkaline medium, the obtained power and efficiency for the small Al alloy electrode (0.2 cm × 0.3 cm) are 3107.8 μW and 24.78 %, respectively, while the obtained power and efficiency for the large Al alloy electrode (1.0 cm × 1.0 cm) are 3423.4 μW and 4.44 %, respectively. The observed electrical power output for the photogalvanics of Al metal and Al alloy is significantly higher compared to most of the reported photogalvanic results using Pt electrodes. Indeed, the results obtained in this study are among the highest reported to date for electrodes used in similar research.