Au nanoparticles decorated SrTiO3−x hollow structure for plasmatic enhanced hydrogen production in UV–visible and near-infrared region

Designing photocatalysts with a broad reaction to sunlight is crucial for efficient clean energy conversion. However, most catalysts reported so far can only respond to UV and visible light for photocatalysis, neglecting the utilization of near-infrared light, which accounts for almost 50% of sunlight. In this study, we obtained Au nanoparticles (NPs) decorated porous hollow SrTiO3 material rich in oxygen defects using an acid etching-assisted hydrothermal method. The formation of a Schottky heterojunction between Au and SrTiO3-x with matched Fermi levels enhances the electron transfer ability of SrTiO3-x. Additionally, Au NPs exhibit two types of surface plasma resonance (SPR) effects at 480 nm (transverse SPR) and 800 nm (longitudinal SPR in the near-infrared region) by absorbing specific photons emitted by SrTiO3-x. The "hot" electrons of the photoexcited SPR state can be further injected into the CB of SrTiO3-x. Furthermore, the local electromagnetic field around the SPR-enhanced Au NPs effectively promotes the excitation and transfer kinetics of photoelectrons, allowing more "hot" electrons to participate in the photocatalytic reaction. Besides, the unique hollow porous structure of the catalyst ensures multiple reflections of sunlight within SrTiO3-x. As a result, the hydrogen production efficiency of Au-SrTiO3-x under near-infrared (NIR) and UV-vis-NIR light irradiation reaches 850 and 3206 μmol h-1g-1, with apparent quantum efficiency of 6.4% and 7.2% at 820 nm and 420 nm, respectively. The possible photocatalytic mechanism was proposed based on thorough systematic experimental analysis and theoretical calculations.