Nanocomposites of Three-Dimensionally Ordered Porous TiO₂ Decorated with Pt and Reduced Graphene Oxide for the Visible-Light Photocatalytic Degradation of Waterborne Pollutants

A new photocatalyst was developed by coupling three-dimensionally ordered macroporous (3DOM) TiO2 with platinum (Pt) and reduced graphene oxide (rGO) for water purification applications under visible light. The rGO/Pt/3DOM TiO2 ternary photocatalyst was synthesized by codecoration of 3DOM TiO2 prepared by the colloidal crystal templating approach with Pt nanoparticles and rGO nanosheets via impregnation and in situ reduction methods. Modification with Pt and rGO reduced the band energy and significantly improved the visible light absorption of the rGO/Pt/3DOM TiO2 photocatalyst. The performance of rGO/Pt/3DOM TiO2 was investigated for the photodegradation of methyl orange as a model dye pollutant in water under visible light irradiation. rGO/Pt/3DOM TiO2 enhanced the degradation rates of methyl orange by a factor of 6, 4, and 2 compared to bare 3DOM TiO2, Pt/3DOM TiO2, and rGO/3DOM TiO2, respectively. The significantly enhanced photocatalytic activity of rGO/Pt/3DOM TiO2 may be attributed to the synergy of the highly ordered 3DOM structure that induced the slow photon effect and the decorated Pt and rGO that promoted light absorption and charge separation. The rGO/Pt/3DOM TiO2 ternary photocatalyst showed high stability and can be used for several cycles without reducing activity. Results suggested that rGO/Pt/3DOM may hold promises as a visible light photocatalyst for the removal of waterborne contaminants.