Historically, nanoscience research has been centered around three classes of nanomaterials based on their dimensionalities: C60 & quantum dot (0-dimensional, 0D), nanotube and nanowire (1D), graphene and 2D materials (2D).
Semiconductor nanowires have witnessed an explosion of interest in the past two decades due to advances in synthesis and the unique thermal, optoelectronic, chemical, and physical properties of these materials. The potential applications of single-crystalline nanowires are truly impressive, including computational nanotechnology, telecommunications, spectroscopic sensing, renewable energy, and the biological sciences. This breadth of application naturally requires a multidisciplinary community, including but not limited to materials scientists, chemists, engineers, physicists, and microbiologists, all converging to solve challenging problems at nanometer length scales.
Semiconductor systems with photon, phonon and/or electron confinement in two dimensions (i.e. nanowires) offer a distinct way to study electrical, thermal, mechanical, and optical phenomena as a function of dimensionality and size reduction. These structures have cross-sectional dimensions that can be tuned from 5 to 500 nm, with lengths spanning hundreds of nanometers to millimeters. The vapor-liquid-solid crystal growth mechanism has been utilized for the general synthesis of nanowires of different compositions, sizes, and orientation. Achieving such high level of synthetic control over nanowire growth allows us to explore some of their very unique chemical and physical properties. For example, semiconductor nanowires can function as self-contained nanoscale lasers, sub-wavelength optical waveguides, photodetector and efficient nonlinear optical mixer. In addition, semiconductor nanowire arrays can be used as potential substrates to achieve high energy conversion efficiency in photovoltaics, thermoelectrics and artificial photosynthesis.
One emerging and exciting direction is their application for solar to fuel conversion, or more broadly defined, solar-powered production of value-added chemicals from CO2 and H2O. Semiconductor nanowires represent an important class of nanostructure building block for direct solar-to-fuel application because of their high surface area, tunable bandgap and efficient charge transport and collection. Nanowires can be readily designed and synthesized to deterministically incorporate heterojunctions with improved light absorption, charge separation and vectorial transport. Meanwhile, it is also possible to selectively decorate different oxidation or reduction catalysts onto specific segments of the nanowires to mimic the compartmentalized reactions in natural photosynthesis.
Research projects are active in the following areas (click to learn more):