Off-Grid Electrocatalytic Water Treatment Combined with CO₂ Conversion Driven By Photovoltaic Cells

This study purposes the development of off-grid electrolysis system combined water treatment with CO2 conversion driven by sunlight. To enhance the low faradaic efficiency (FE) of (in)organic contaminant decomposition because of competition with water oxidation, reactive chlorine species (RCS), produced by chloride oxidation, is used to oxidizing agent for contaminant in aqueous solution. We conducted a research focused on arsenite (As(III)), a common and highly toxic pollutant in aqueous system, and proved that the presence of chloride in aqueous solution doubled FE of As(III) oxidation. CO2 reduction reaction (CO2RR), which is the counter reaction of improved anodic reaction, is carried out on electrodeposited Bi nanoparticle electrocatalyst, and produced formate. Formate was produced with FE of 100 % on Bi electrocatalyst when the electrolysis system was satisfied with the specific condition. The overall redox system was designed to concentrate on the simultaneous driving of these two different optimized reactions without degradation the performance compare to half-reactions. Finally, a stand-alone hybrid system operated without external power was developed through a combination of solar cells and hybrid system. In order to efficiently operate the PV-electrolysis hybrid system, the conditions of the solar cells were optimized to suit the power demands and experimental conditions of each hybrid system. As a result, the PV-electrolysis hybrid system with a solar-to system conversion efficiency more than 10% was implemented, and there were no difference in FE of the redox reaction compared to when it was operated using an external power source.