Designing Au Surface-Modified Nanoporous-Single-Crystalline SrTiO3 to Optimize Diffusion of Surface Plasmon Resonance-Induce Photoelectron toward Enhanced Visible-Light Photoactivity

Nanoporous single-crystalline SrTiO3 is fabricated at a low temperature of 60 °C via a novel approach of sol–gel alkali-dissolution-exothermal reaction. The plasmon-active metal Au is loaded on the nanoporous single-crystalline SrTiO3 material to construct a new kind of plasmonic photocatalyst. Due to the single-crystalline nature and the space confinement effect of pores for Au growing, not only the promoted diffusion efficiency of surface plasmon resonance (SPR)-induce photoelectron is achieved, but also the diffusion region are well optimized via changing the loading amount of Au. Therefore, an optimal sample with 4.8 wt % Au loading exhibits a more than 40-fold photoactivity enhancement under visible-light irradiation compared to the common nanosized SrTiO3 (a commercially available sample) loaded with 5.3 wt % Au which was prepared under the same condition. Furthermore, combining the special nanostructure of Au surface-modified nanoporous-single-crystalline SrTiO3 with photocatalytic properties, estimation of the diffusion mean free path of SPR-induce photoelectron can be achieved. This study proposes an alternative approach to enhance the photoactivity of plasmonic photocatalyst via fine designing the semiconductor substrate.