Synthesis of Stable Ligand-free Gold-Palladium Nanoparticles Using a Simple Excess Anion Method
Synthesis of Stable Ligand-free Gold-Palladium Nanoparticles Using a Simple Excess Anion Method
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DOI：
10.1021/nn302299e
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发表时间：
2012-08-01
期刊：
影响因子：
17.1
通讯作者：
Hutchings, Graham J.
中科院分区：
文献类型：
--
作者：
Sankar, Meenakshisundaram;He, Qian;Hutchings, Graham J.
我们报告了一个方便的过量阴离子改性和后还原步骤的浸渍方法，该方法允许可重复的制备支撑的AuPd nanopartides具有紧密的粒度分布相媲美的溶胶固定化材料，但没有复杂的配体吸附在颗粒表面上。与通过常规浸渍制备的那些相比，改性的浸渍材料的有利特征包括较小的平均粒度、优化的无规合金组成和颗粒间改进的组成均匀性，从而导致与使用常规浸渍和溶胶固定化方法制备的催化剂相比更高的活性和稳定性。详细的STEM与单个颗粒的EDX分析相结合揭示了阴离子浓度的增加增加了所得催化剂中单个颗粒的金含量，从而提供了控制/调节纳米合金颗粒组成的方法。这些新的催化剂的改进的活性和稳定性的特点，证明使用（i）过氧化氢的直接合成和（ii）苯甲醇的无溶剂有氧氧化作为案例研究。
We report a convenient excess anion modification and post-reduction step to the impregnation method which permits the reproducible preparation of supported bimetallic AuPd nanopartides having a tight particle size distribution comparable to that found for sol-immobilization materials but without the complication of ligands adsorbed on the particle surface. The advantageous features of the modified impregnation materials compared to those made by conventional impregnation include a smaller average particle size, an optimized random alloy composition, and improved compositional uniformity from particle-to-particle resulting in higher activity and stability compared to the catalysts prepared using both conventional impregnation and sol immobilization methods. Detailed STEM combined with EDX analyses of individual particles have revealed that an increase in anion concentration increases the gold content of individual particles in the resultant catalyst, thus providing a method to control/tune the composition of the nanoalloy particles. The improved activity and stability characteristics of these new catalysts are demonstrated using (i) the direct synthesis of hydrogen peroxide and (ii) the solvent-free aerobic oxidation of benzyl alcohol as case studies.