Catalysis by Shape Selected Metallic Nanoparticles: Mechanism of Shape Control and Nanoparticle Stability

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This project, supported in the Analytical and Surface Chemistry Program, focusses on the characterization of transition metal nanoparticles prepared by a process involving hydrogen reduction and control of particle shape by the presence of capping polymers. Professors El-Sayed and Wang and their students at Georgia Tech will characterize the shape and composition of these nanoparticles using high resolution transmission electron microscopy, parallel- detection electron energy-loss spectroscopy, energy-dispersive X- ray spectroscopy, and Raman and FTIR vibrational spectroscopies. The objective is to establish an understanding of the synthetic parameters that control the shapes of these nanoparticles and their properties. The long-term aim of this work is to develop useful nanoparticle structures for applications in heterogeneous catalysis. A new synthetic process for preparing transition metal nanoparticles that can control their shape has been developed by Professors El-Sayed and Wang at Georgia Tech. This process involves reduction of metal ions using molecular hydrogen in the presence of polymers that cap the particle surface. The factors that are important in controlling the size, shape, and composition of these particles will be determined using an array of surface characterization methods, particularly high resolution transmission electron microscopy. The long-term goal of this work is to develop a family of new low temperature heterogeneous catalysts for industrial use.