Suzuki cross-coupling reactions over engineered AuPd alloy nanoparticles by recycling scattered light

Photocatalyzed organic transformations have spurred immense interest in synthetic chemistry for the efficient conversion of solar energy into chemical energy.However,the crucial roles of support,which fixes catalytic sites and improves the light-harvesting ability,are often ignored in photoredox transformations.Herein,we report the utilization of spherical SiO2 support to engineer AuPd alloy particles(denoted as AuPd/SiO2),conceptually different from traditional methods for tuning optical absorption of plasmonic Au or AuPd particles,to manipulate light-harvesting ability of AuPd particles for highly selective and efficient photocatalytic Suzuki cross-coupling reactions.In this deliberately designed system,typically without the size and shape alternation of AuPd particles,the supported AuPd particles recycle the scattering light from spherical SiO2 support and achieve the significant broad light-harvesting ability instead of the surface plasmon resonance peak.The engineered AuPd/SiO2 composites by the use of near-field scattering-promoted optical absorption showcase the remarkably enhanced activity for visible-light-induced photocatalytic Suzuki cross-coupling reactions in comparison with that using commercial SiO2 support,highlighting the spherical-support-effect induced efficient utilization of scattered light.This work highlights the feasibility of manipulating the light-harvesting capability of bimetallic particles by the near-field scattering-promoted optical absorption model toward efficient photo-driven Suzuki cross-coupling reaction and other C-C coupling organic synthesis to produce high value-added chemicals.

Synthesis of graphene-supported monodisperse Au Pd bimetallic nanoparticles for electrochemical oxidation of methanol

Monodisperse Au Pd bimetallic nanoparticles（NPs） with different compositions are synthesized by using oleylamine（OAm） as reducing reagent, stabilizer, and solvent. To obtain Au Pd solid solution NPs, Pd–OAm and Au–OAm precursors are firstly prepared by mixing OAm with Palladium（II） acetylacetonate（Pd（acac）2） and HAu Cl4, respectively. Then Pd–OAm and Au–OAm precursor solutions are injected into a hot oleylamine solution to form Au Pd NPs. The size of these NPs ranges from 6.0 to 8.0 nm and the composition is controlled by varying the precursor ratio. The Au Pd NPs are loaded onto reduced graphene oxide（RGO） sheets to make catalysts. Alloy NPs show high electrocatalytic activity and stability toward methanol oxidation in the alkaline media. Their catalytic activity for methanol oxidation is found to be dependent on the NP composition. As the Pd component increases, the peak current densities during the forward scan gradually increase and reach the maximum at Au Pd2. The enhancement of alloy NPs for methanol oxidation can be attributed to a synergistic effect of Au and Pd on the surface of alloy NPs.

Au/CuSiO3 nanotubes: High-performance robust catalysts for selective oxidation of ethanol to acetaldehyde

Novel gold-supporting silicate nanotubes are synthesized via a hydrothermal method followed by colloid deposition. Their catalytic performance for the selective oxidation of ethanol to acetaldehyde is assessed. The results show that Au/CuSiO3nanotubes exhibit both high activity and selectivity at high gas hourly space velocity (GHSV). Ethanol conversion can reach up to ~98%, and the selectivity for acetaldehyde is ~93% at 250 °C and ~100,000 mL·gcat–1·h–1. In comparison, the catalytic activity of Au/MgSiO3nanotubes is relatively low, and ethanol conversion reaches only ~25% at 250 °C. However, when Cu species are added to Au/MgSiO3, the catalytic activity improves significantly, indicating that the interactions between Au nanoparticles and Cu species are responsible for the high performance for selective oxidation of ethanol to acetaldehyde. [Figure not available: see fulltext.] © 2016, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.