Transparent titania coating was formed onto a flexible polycarbonate plastic substrate by low-temperature fabrication process below 100 °C consisting of a sol-gel technique and a hot water treatment method. The titania coating with high transparency showed a good photocatalytic activity under ultraviolet (UV) light irradiation. Palladium metal acts as a catalyst for dissociative adsorption of hydrogen gas at room temperature under an atmospheric pressure. The palladium catalyst was deposited on the photocatalytic titania coating by a photodeposition process at room temperature under UV-light irradiation. The flexible polycarbonate plastic sheet with semitransparent palladium-deposited titania coating works as an optically readable hydrogen gas sensor which can operate at room temperature.
Semiconductor-type SnO2-based NO2 sensors operated at room temperature under UV-light irradiation