The Evolution of Gold Nanoparticles in the Presence of Configurational Ion Cu²⁺ of Hydrotalcites Supports

Abstract

Controlled synthesis of gold nanoparticles had attracted much attention in catalysis. The evolution of gold nanoparticles by impregnation was investigated in the presence of configurational ion Cu2+ of hydrotalcites supports. The formation of Au nanoparticles experienced two steps. In the drying step, part of Au ions was reduced by H2O. The reducing extents of Au ions and the dispersion of Au nanoparticles were affected by configurational ion Cu2+ in the hydrotalcites supports. In the reduction step, all the residue Au ions were reduced by H2 and the Au nanoparticles formed in the previous step was redistributed. Both the redistribution of Au nanoparticles formed in the previous step and the distribution of Au nanoparticles formed in the second step was affected by the surface reaction between Au on the surface of supports and Cu embedded in the supports. The surface reaction controlled the dispersion of Au nanoparticles. The size of gold nanoparticles was 2.7 nm, which showed high activity in benzyl alcohol oxidation with benzaldehyde yield of 95%.