Optimization of c/rh-In₂O₃-Based Electrode Technology for Photoelectrochemical Systems

This work systematically investigated the influence of fabrication parameters on photoelectrodes of a biphasic indium oxide polymorph (In₂O₃) with cubic (c-) and rhombohedral (rh-) phase contents of 72 and 28%, respectively, deposited on the surface of conductive fluorine-doped tin oxide (FTO) glass. The study examined the effects of varying the concentration of c/rh-In₂O₃ suspension, the composition of the dispersion medium, the number of cycles, and the mode of suspension application onto FTO glass. Linear voltammetry, chronoamperometry, and impedance spectroscopy in the illumination mode were used to demonstrate that the photoelectrode made with a suspension based on isopropyl alcohol at an c/rh-In₂O₃ concentration of 100 g/L exhibited the highest photocurrent density and the lowest charge transfer resistance in an aqueous electrolyte solution of 0.5 M Na₂SO₄ + 0.25 M Na₂SO₃. It has been shown that the optimal approach was to apply three layers using a multistage application mode. The results obtained can be used as a basis for the development of optimization protocols for the photoelectrodes based on oxide-containing systems and photoelectrochemical devices based on c/rh-In₂O₃ material.