Noble metal nanoclusters and their in situ calcination to nanocrystals: Precise control of their size and interface with TiO2 nanosheets and their versatile catalysis applications

Abstract

In this work, we present a new versatile strategy to prepare noble metal (Au, Ag and Cu) nanoclusters on TiO2 nanosheets in large scales with exposed (001) facets with controlled size, crystalline interface, and loading amount. By precise in situ calcination, the metal (M = Au, Ag, and Cu) nanocrystals with controllable size and better crystalline interface with the TiO2 support have been prepared. The potential application of the as-prepared Au, Ag, and Cu nanoclusters on TiO2 nanosheets as potential heterogeneous catalysts for organic synthesis, such as catalytic reduction of 4-nitrophenol to 4-aminophenol, has been demonstrated. After calcination, Au, Ag, and Cu nanocrystals were found to be proficient cocatalysts for photocatalytic H2 evolution, particularly the Au cocatalyst. Based on precise high-resolution transmission electron microscopy (HRTEM) and inductively coupled plasma optical emission spectrometry (ICP-OES) analyses, the flexible control of their size and loading amount as well as their intimate contact with the TiO2 nanosheet enhanced the photocatalytic H2 evolution activity and the sensitivity of the photocurrent response of the film. Furthermore, this aqueous-directed synthesis of metal nanoclusters on a support will generate further interest in the field of nanocatalysis.