Spectroscopic investigation of titania-supported gold nanoparticles prepared by a modified deposition/precipitation method for the oxidation of CO

The spectroscopic characterization of a material is a fundamental tool for understanding the structure-activity correlation for catalytic purposes. Regarding supported nanoparticles, this perspective has acquired more relevance in recent years and several techniques have been employed. In this work diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), coupled with CO adsorption, was used to investigate a modified deposition/precipitation method (DP-UC) for the preparation of supported gold nanoparticles with very low metal loading (0.1-0.5wt%). This promising synthetic route involves the use of urea as basic agent and NaBH4 as chemical reductant in contrast to the traditional high-temperature reduction step. The systematic IR spectroscopic study of the Au loading was combined with CO oxidation catalytic tests. The evaluation of the results was also supported by several other techniques, such as X-ray photoelectron spectroscopy, N2 physisorption, and transmission electron microscopy. Particular attention was given to the evaluation of the gold electronic state, surface dispersion, particle size, and the corresponding structure-activity relationship.