Versatility of Supported Gold Nanoparticles on Hydrotalcites used for Oxidation and Reduction Reactions

Regardless of their size, supported gold nanoparticles are largely used for liquid-phase oxidation reactions. Small gold nanoparticles exhibit good performance during the reduction of organic compounds. The direct reduction of carboxylic acid to aldehyde is a famous and familiar reaction in the field of organic chemistry and is considered as one of the fundamental chemical transformations. Herein, we present Au/hydrotalcite, Au/MgO, and Au/Al2O3 systems as heterogeneous versatile catalysts to realize the oxidation of furfural (FF) to furoic acid (FA) and realize the reduction of FA to FF. Experiments showed that in standard aqueous conditions under air, FF can be easily oxidized to FA. When DMSO was used as a solvent to conduct the experiments under an atmosphere of CO2, FA was reduced to FF. The Au/HT series of catalysts was found to be active in both transformations, pointing out the versatility of the gold-based catalysts. The activity significantly depends on the acid-base properties of the catalyst.

Hydrogenation of HOPG-Supported Gold Nanoparticles: Surface or Volume?

The hydrogenation features of gold nanoparticles deposited on highly oriented pyrolytic graphite were determined, and composite nanostructures consisting of pure and hydrogenized gold were synthesized. Methods of scanning tunneling microscopy and spectroscopy have been successfully used to probe the bottom of the conductive band and to determine the shape of the electron energy barrier in hydrogenized gold. Considering models of surface and volume hydrogenation, we have shown that no hydrogen dissolution occurred in gold nanoparticles, but all changes in their electronic structure were associated with surface processes. The results of the quantum chemical simulation also corresponded with this conclusion.

One Step Photochemical Synthesis of Surface-Supported Naked Gold Nanoparticles and Its Application as a SERS Substrate

<p>A direct and straightforward method is proposed to synthetize a surface-supported gold nanoparticles mediated by pulsed laser irradiation of quartz surfaces in contact with a gold precursor solutions. The substrates´ performance as SERS sensors is tested by the Rhodamine 6G (R6G) Raman signal enhancement.</p>

One Step Photochemical Synthesis of Surface-Supported Naked Gold Nanoparticles and Its Application as a SERS Substrate

<p>A direct and straightforward method is proposed to synthetize a surface-supported gold nanoparticles mediated by pulsed laser irradiation of quartz surfaces in contact with a gold precursor solutions. The substrates´ performance as SERS sensors is tested by the Rhodamine 6G (R6G) Raman signal enhancement.</p>