Water-splitting Reactor Comprising a Combination of TiO2-based Photoelectrochemical Cell and Serially Connected TiO2/Se Heterojunction Photovoltaic Devices

In this paper, we report on a photocatalytic water-splitting device comprising a TiO 2 photoanode combined with Se/TiO 2 heterojunction photovoltaic (PV) devices.A Se/TiO 2 PV device can supply its photo-induced open circuit voltage to a TiO 2 -Pt photoelectrochemical cell (PEC) in order to assist photoelectrolysis for H 2 and O 2 gas generation without external electrical sources.The open circuit voltage was increased from 0.65 V to approximately 3.2 V by the serial connection of five Se/TiO 2 PV devices.Hydrogen and oxygen bubbles were successfully generated by only light illumination without using any wired external voltage source.A photoanode with sol-gel derived porous TiO 2 films was used to increase the surface area to attain a stronger photocatalytic reaction.Microdot patterns of Pt were formed as the co-catalyst on a TiO 2 photoanode to suppress the back reaction of the photogenerated carrier.A Pt anode was formed on a glass substrate.Parameters related to the photocatalytic reaction, such as atmospheric pressure, the type of chemical additive, and the area ratio of Pt co-catalyst patterns to the surface area of the TiO 2 photoanode, were varied to generate a larger gas volume with the water-splitting device.