Hybrid nanomaterials and their structure-property-performance relations for catalysis, green energy and nanoelectronics applications

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In the past five years, we have achieved a number of important studies on the interfacial chemistry of (a) bio/organic molecules on Si single-crystal surfaces, and (b) nanostructures of transition metals (and their oxides) and transparent conductive oxides on Si and other (templated) substrates. As material and structural imperfections have become an often unavoidable yet extremely important part of the entire material, we will focus, in the next five years, on defects-driven phenomena in these hybrid nanomaterials. While the presence of defects is often viewed as detrimental to some material properties, control of these defects can also be highly beneficial to a number of important material properties, especially when the material size approaches the nanoscale. This has been demonstrated by our recent discovery of extraordinary photocatalytic power in defect-rich TiO2 nanowires for the water-splitting reaction (for hydrogen fuel cell application). Our mission is to study defects in benchmark nanomaterials and to obtain better understanding of their formation and evolution mechanisms in different growth, processing or treatment strategies. The three primary classes of nanomaterials of particular interest are (in the order of increasing size): ultrasmall nanoclusters (< 5 nm), nanocrystallites (5-100 nm), and low-dimensional nanostructures of transition metals (and their oxides) and transparent conductive oxides. Our objective is to develop protocols to manipulate these defects and to optimize the structure-property-performance relations of defect-controlled materials for applications in chemical sensing and drug delivery, green energy, and nanoelectronics. We will employ the full fleet of advanced materials characterization and synthesis tools available at the core material research facility at the University of Waterloo to investigate several fundamental questions. These include: (a) the chemistry of site-specific defects in nanoclusters as a function of cluster size; (b) mechanisms of defect formation in nanostructures; (c) interactions of bio/organic adsorbates with nanoclusters and nanostructures with different defect-site compositions; and (d) substrate effects. These experiments will be supported by large-scale ab-initio computational studies in order to obtain new insights into these basic concepts. The proposed work will also allow us to fully exploit the use of these new defect-controlled, hybrid nanomaterials for important emerging applications, including multiplex chemical sensing and drug delivery to advance our medical research tools, super-efficient photocatalysts for water splitting for solar-to-hydrogen generation to increase our green energy capacity and to reduce global warming, and memristors as the next-generation nanoelectronics to propel us to a transistor-free world.