Three-dimensionally ordered hollow sphere array Pt/In2O3–TiO2 with improved photocatalytic efficiency

Abstract

The three-dimensionally ordered hollow sphere array composite Pt/In₂O₃–TiO₂ was prepared by a vacuum impregnation, solidification and calcination treatment using polystyrene (PS) microspheres as the template. The samples were characterized by X-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy (UV-vis/DRS), photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and N₂ adsorption–desorption measurements. The results show that the hollow spherical Pt/In₂O₃–TiO₂ composite is composed mainly of a mixed titanium dioxide crystal phase of anatase and rutile, and a small part of the cubic phase of In₂O₃ and cubic phase Pt. Compared with monomer TiO₂, the composite material has a significantly enhanced absorption in the visible region, and a red shift occurs to some extent. The synthesized composite material Pt/In₂O₃–TiO₂ shows a highly regular three-dimensionally ordered hollow sphere array state. The ability to degrade pollutants under multi-mode photocatalytic conditions and the ability of photocatalytic hydrogen production under a xenon lamp were studied. The experimental results show that the ordered hollow sphere array composite Pt/In₂O₃–TiO₂ exhibits better photocatalytic activity than the single components or two components and Pt/In₂O₃–TiO₂. In addition, the hollow spherical Pt/In₂O₃–TiO₂ composite exhibits different performances of hydrogen production in the presence of different sacrificial agents. When triethanolamine is used as a sacrificial agent, its hydrogen production can reach 404.6 μmol g⁻¹ (8 h), which is nearly 7 times that when adding methanol as a sacrificial agent. Finally, the reasons for the photocatalytic activity of the ordered hollow sphere array Pt/In₂O₃–TiO₂ composite were systematically analyzed, and the possible photocatalytic reaction mechanisms of the Pt/In₂O₃–TiO₂ composite under different conditions of ultraviolet and visible light were discussed.