Synthesis of fine gold nanoparticles in mesoporous titania nanoparticles through different reduction methods.

This study focuses on the synthesis of gold nanoparticles-embedded mesoporous titania nanoparticles (Au@MTNs). Recently, mesoporous titania materials doped with noble metals such as gold, silver and platinum have attracted considerable attention because noble metals can enhance the efficiency of mesoporous titania-based devices. In this research, we attempted to use four different reduction methods (i.e., thermal treatment, UV irradiation, vapor infiltration, liquid immersion) to introduce gold nanoparticles (Au NPs) into MTNs. The synthesized Au@MTNs nanomaterials were characterized with UV-Vis spectra, X-ray diffraction (XRD), N2 adsorption-desorption isotherm, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Among these different reduction methods, we found that only thermal treatment could successfully and homogeneously introduce Au NPs inside the MTNs, and the size of the produced Au NPs was around 7 nm. In contrast, the other reduction methods suffered the difficulty to penetrate the whole particle of MTNs, resulting in very few or no Au NPs. The synthesized Au@MTNs nanomaterials show great potentials in various photo-electronic and photo-catalytic applications.