Photocatalytic Water Splitting on KTa(Zr)O₃Modified with Acene-Based Organic Semiconductors

The modification effect of acene dyes such as 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-PEN) and difuranoanthracene derivatives on the photocatalytic water splitting activity of Pt-loaded KTa(Zr)O3 was studied. The surface modification of KTa(Zr)O3 powder with acene dyes was conducted with an evaporation-to-dryness method using pyridine as a solvent. TIPS-PEN is the most effective dye for increasing the hydrogen formation rate on the KTa(Zr)O3 catalyst, which became larger by 14 times. The fluorescence spectrum of the TIPS-PEN-modified catalyst revealed that the excitation energy of KTa(Zr)O3 was transferred to the Pt cocatalyst through the TIPS-PEN moiety. The wavelength dependence of the photocatalytic activity was investigated, and the water splitting activity was improved by irradiating with both ultraviolet and visible light comparing with the case of irradiating with only ultraviolet light. Furthermore, the water splitting reaction did not occur under visible light irradiation, which suggests that a Z-scheme-type water splitting reaction, that is, a two-step photoexcitation mechanism similar to that occuring in plant photosynthesis, proceeded on PtOX/TIPS-PEN/KTa(Zr)O3.