Highly Crystalline Mesoporous Titania Loaded with Monodispersed Gold Nanoparticles: Controllable Metal-Support Interaction in Porous Materials.

We report the syntheses of mesoporous Au/TiO hybrid photocatalysts with ordered and crystalline frameworks using co-assembly of organosilane-containing colloidal amphiphile micelles (CAMs) and poly(ethylene oxide)-modified gold nanoparticles (AuNPs) as templates. The assembled CAMs can convert to inorganic silica during calcination at elevated temperatures, providing extraordinary thermal stability to preserve the porosity of TiO and the nanostructures of AuNPs. Well-defined AuNPs supported within mesoporous TiO (Au@mTiO) can be prepared using thermal annealing at temperatures up to 800 °C. High-temperature treatment (≥500 °C) under air is found to not only improve the crystallinity of TiO but also induce oxidative strong metal-support interactions (SMSIs) at Au/TiO interfaces. For oxidative SMSIs, the surface oxidation of AuNPs can generate positively charged Au species, while TiO gets reduced simultaneously. Using photocatalytic oxidation of benzyl alcohol as a model reaction, Au@mTiO calcined at 600 °C for 12 h exhibited the best activity under UV irradiation, while Au@mTiO calcined at 600 °C for 2 h showed the best activity under visible light. The delicate balance between the crystallinity and porosity of TiO and the SMSIs at Au-TiO interfaces is found to impact the photocatalytic activity of these hybrid materials.