Photoelectrochemical water splitting for hydrogen production using combination of CIGS2 solar cell and RuO2 photocatalyst

This paper presents the development of photoelectrochemical (PEC) cell for water splitting setup using multiple band gap combination of CuIn1−xGaxS2 (CIGS2) thin-film photovoltaic (PV) cell and ruthenium oxide (RuO2) photocatalyst. FSEC PV Materials Lab has developed a PEC setup consisting of two illuminated CIGS2 cells, a ruthenium oxide (RuO2) anode deposited on titanium sheet for oxygen evolution and a platinum foil cathode for hydrogen evolution. With this combination, a PEC efficiency of 4.29% has been achieved. This paper also presents the research aimed at further improvements in the PEC efficiency by employing highly efficient photoanode that can be illuminated by photons not absorbed at the PV cell and by increasing the concentration of electrolyte solution (pH 10). The former will be achieved by employing a p-type transparent and conducting layer at the back of PV cell to transmit the unabsorbed photons, and the latter will reduce the resistance offered by the electrolyte.Concentration of the electrolyte was increased by five times, and the I–V characteristics of both RuO2 and RuS2 were measured with and without illumination. The results indicate that PEC efficiencies of over 9% can be achieved using RuS2 with illumination and five times concentrated pH 10 solution instead of pH 10 with normal concentration.