Systematic investigations of the surface properties of metal nanoparticles and their applications

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Understanding and tuning the properties of nanomaterials (1 nanometer = 1 billionth meter) such as nanoparticles (NPs) play a crucial role in the development of nanoscience and technology. The properties of NPs are dramatically different from their bulk counterpart due to the so-called quantum-size effect and surface effect. The quantum-size effect is mainly caused by the confinement of electrons of the materials in a nano-sized geometry where the quantum mechanics play a predominant role. As a result, properties of the NPs are often size-dependent. The surface effect is due to the large surface-to-volume ratio of NPs. As a consequence, appropriate modifications of the surface environment of NPs will result in significant changes in their properties.  Among the various properties of NPs, understanding the surface-relevant properties is of fundamental importance and yet very difficult mainly due to the challenge in the chemical synthesis of high quality NPs, i.e. NPs with monodisperse size and properly tailored surface chemistry, size and composition and the technical challenge in studying the surface properties of NPs. In the first area of my proposed research, significant efforts will be devoted to systematically investigating the surface properties of metal NPs with the emphasis on overcoming the above-mentioned challenges in chemical synthesis and characterization methodology. A broad range of high-quality metal NPs with properly tailored surface chemistry, alloy composition and particle size will be synthesized using a novel synthetic method. Then a variety of surface-sensitive synchrotron-based spectroscopy methods, including both existing and novel ones, will be developed and used to obtain a whole physical picture of the the surface properites of the NP systems. Two aspects of novel applications based on the surface properties of NPs will be proposed.