Tio2/Co3O4 Composite as Photoanode of Photoelectrochemical Water Splitting

Abstract

Titanium dioxide is one of the most investigated materials for photoelectrochemical (PEC) water splitting. However, TiO2 has a wide band gap of approximately 3.2 eV, which limits its absorption energy to UV only, and the photoexcitation products (i.e., electron and hole) easily recombine. Developing a composite with other semiconductor materials is one of the efforts for improving the performance of TiO2 photoelectrode. In this study, a composite of TiO2/Co3O4 thin films was developed, and its performance in PEC water splitting was investigated. Co3O4 was synthesized using a hydrothermal method, and TiO2 P25 was used. TiO2 and Co3O4 were mixed by ball milling before coating on a clean FTO and annealing at 550 °C. Two weight variations of TiO2:Co3O4 were used (95:5 and 90%:10%). XRD and FESEM analysis were used to investigate crystallinity phase and surface morphology. The optical band gap of the thin films was determined by UV-Vis spectroscopy, where the film with 90:10 weight ratio of TiO2:Co3O4 obtained the smallest band gap of 2.9 eV. Co3O4 improved the current density and TiO2 performance by approximately three times.