Selective oxidation of glycerol mediated by surface plasmon of gold nanoparticles deposited on titanium dioxide nanowires.

This paper describes an alternative method for the in situ synthesis of gold nanoparticles (AuNPs) with a particle size of less than 3 nm, using nanoreactors formed by reverse micelles of 1,4-bis-(2-ethylhexyl) sulfosuccinate sodium (AOT) and nanoparticle stabilization with l-cysteine, which favor the preparation of nanoparticles with size and shape control, which are homogeneously dispersed (1% by weight) on the support of titanium dioxide nanowires (TNWs). To study the activity and selectivity of the prepared catalyst (AuNPs@TNWs), an aqueous solution of 40 mM glycerol was irradiated with a green laser (λ = 530 nm, power = 100 mW) in the presence of the catalyst and O2 as an oxidant at 22 °C for 6 h, obtaining a glycerol conversion of 86% with a selectivity towards hydroxypyruvic acid (HA) of more than 90%. From the control and reactions, we concluded that the Ti-OH groups promote the glycerol adsorption on the nanowires surface and the surface plasmon of the gold nanoparticles favors the selectivity of the reaction towards the hydroxypyruvic acid.

Selective Photooxidation of Valencene and Thymol with Nano-TiO2 and O2 as Oxidant.

The selective photocatalytic oxidation with O2 as oxidant of valencene and thymol was evaluated using nanostructured TiO2 under UV-Vis radiation at atmospheric conditions. The effect of the morphology and optical properties of TiO2 nanotubes and aminate nanoparticles was studied. Different scavengers were used to detect the presence of positive holes (h+), electrons (e-), hydroxyl radicals (•OH), and the superoxide radical anion (O2-) during the photooxidation reaction. Superoxide anion radical is the main oxidizing specie formed, which is responsible for the selective formation of nootkatone and thymoquinone using aminated TiO2 nanoparticles under 400 nm radiation.