Pyramidal Metal–dielectric hybrid-structure geometry with an asymmetric TiO2 layer for broadband light absorption and photocatalytic applications

Abstract

In this study, a pyramidal metal–dielectric hybrid-structure geometry with high broadband light absorption was prepared and applied as a photoelectrode for solar water oxidation. TiO2 was obliquely deposited on the pyramidal Au film, leading to asymmetrically thick pyramids. With the decoration of Au nanoparticles, the light absorption in the entire UV–visible region significantly increased to > 90%, which was examined by three-dimensional finite-difference time-domain simulations and confirmed by confocal spectral mapping techniques. By the introduction of Ti as the insertion layer, the alignment of bands at the TiO2/Au film interface was tuned, thereby promoting the separation of photogenerated carriers via the efficient transport of electrons to the Au film. This transport led to a remarkable enhancement in the photocurrent density (~0.16 mA/cm2) by 3.4 times compared to that observed for a flat TiO2 layer.