报告摘要：

A facile, one-pot synthesis procedure has been developed for the preparation of two types of bimetallic Au-Ptnanostructures. By controlling the timing and conditions of the syntheses, gold nanoparticle (AuNP) cores with an atomically thin platinum shell nanoparticles,and encapsulated in a porous network of 2-3 nm platinum nanoparticles (PtNPs)can be prepared, denoted Au@Pt NPs and nanoflowers (NFs), respectively.

The exact concentration of Pt precursor andthe dynamics of its reduction are critical for core-shell formation as rapidprecursor reduction leads to unwanted nucleation of PtNPs. Formation of anatomically thin Pt shell leads to a drastic change in optical properties. The localized surface plasmon resonance (LSPR) of the Au core is almost completely dampened and the colloid changes color from red to brown. Meanwhile, nosignificant change in particle size is detectable by transmission electronmicroscopy (TEM). Electrochemical characterization of the Au@Pt NPs reveals alarge Pt response confirming the formation of a core-shell structure.

The as-synthesized Au@Pt NPs were tested ascatalysts for electrocatalytic oxidation of small organic fuel molecules, i.e.methanol, ethanol and formic acid. Especially promising results were obtained for formic acid oxidation during which the Au@Pt NPs showed good resistance towards poisoning.

The AuNP core size can be controlled througha seeded growth approach from 8 to 80 nm. Varying the reaction conditions during shell synthesis enabled the formation of a porous network of individual2-3 nm PtNPs surrounding a single AuNP core rather than the thin shell deposited directly on the AuNP. Nanoflowers with PtNP network shells from a fewnm to more than 100 nm were prepared.

主讲人介绍：

Christian Engelbrekt from the Nano Chemistry Group at the Technical University of Denmark(DTU) has been working with controlled synthesis of metal-based nanostructuresfor the past 7 years under the supervision of Associate Professor Jingdong Zhang and Professor Jens Ulstrup. He developed the green synthesis protocol SAMENS (saccharide-based approach to metal nanostructure synthesis) producing arange of interesting composite nanostructures with materials such as gold,platinum, palladium, copper oxide and silver.

Christian defended his PhD thesis “Green synthesis and structural control of metal andmineral nanostructures” in 2014 and has since been working as postdoc on the development of gold- and graphene-based nanocomposites for catalysis in energy technology. With a $ 0.5M, 3-year individual postdoc scholarship from the Danish Council for Independent Research, Christian will pursue novel 3-component photocatalysts jointly at the University of California Irvine and DTU starting March 2016.