Structural evolution and Au nanoparticles enhanced photocatalytic activity of sea-urchin-like TiO2 microspheres: An X-ray absorption spectroscopy study

Au nanoparticles decorated on titanium dioxide sea-urchin-like microspheres (TSUMs) were synthesized by a hydrothermal method. Having the gold nanoparticles well decorated on the crystalline spines of TSUMs are expected to increase the photocatalytic activity. XAS results indicate that different Au precursor concentration affects the electronic structure of the TSUM spines. The oxygen defects in the local structural symmetry of TiO6 octahedral are also shown to be strongly correlated with the decoration of Au nanoparticles, as testified by XAS analysis. The oxygen defects and Ti3+ in the spines, generated by the decoration of Au nanoparticles, are considered to enhance photocatalytic degradation of paracetamol. Further, in-situ XAS measurements reveal the hot electron transferred from Au to TSUMs assisted by the localized surface plasmon resonance under visible light irradiation. The investigation provides new insights into the active sites, surface's structure, and its electronic properties of a photocatalyst applicable to environmental problems.