A scalable method for preparing Ti-oxide-based photoanodes from commercial Ti foil, using a simple chemical etching process followed by post-annealing

We demonstrated that Ti-oxide based photoanode for photo-electro-catalytic water splitting can be prepared via a simple surface etching and post-annealing of a commercial Ti foil. Changes of surface structures upon the post-annealing at three different temperatures (400, 600, and 800 °C) were investigated by means of SEM, AFM, XRD and XPS. Their photo-electro-catalytic behaviors for water oxidation were investigated. Among the samples, the 600 °C-annealed photoanode, named 10E600A1, exhibited the highest activity across all experiments (LSV, chronoamperometry) under both UV and simulated sun light irradiations (AM 1.5 G). Its Faraday efficiency (FE%) for hydrogen exceeded 80 %. Electrochemical impedance spectroscopy (EIS) analysis revealed that the efficient charge transfer from the surface of 10E600A1 to electrolyte, largely attributed to its high surface roughness. Additionally, experiments scaling up of the size of 10E600A1 were conducted and it demonstrated that its size can be easily scaled-up while maintaining its photo-electro-catalytic activity for water oxidation.