The impending energy crisis necessitates the development of novel environmentally sustainable approaches to harness and store energy. Nanomaterials with at least one dimension smaller than 100 nm are expected to play a central role in clean energy technologies because of their remarkable tunable physical and chemical properties often not observed for bulk materials. One focus of research in the Banerjee laboratory is the development of nanowire arrays for use as cathode materials in Li-ion batteries. We have recently achieved the fabrication of highly oriented single-crystalline V2O5 nanowire arrays over large areas. The insertion/extraction of Li-ions from these nanowire arrays is much easier than in the bulk because of the shorter solid-state diffusion paths and improved electrolyte interface. These systems are expected to yield novel battery architectures exhibiting high power and energy densities such as required for automotive applications. REU students will work to fabricate various vanadium oxide and vanadium bronze nanowire arrays, characterize these systems by Raman spectroscopy and electron microscopy, and evaluate the Li-ion intercalation properties of these systems. An additional area of focus will be the development of methods to improve upon the V2O5 nanowire arrays by doping with controlled amounts of copper. The students will work alongside graduate students in interdisciplinary teams including collaborators from the National Institute of Standards and Technology (NIST) and the Department of Physics at the University at Buffalo.

A second project is focused on the preparation of materials that can be used to harvest near-infrared (NIR) light from the solar spectrum. One system that is of particular interest involves composites of NIR-absorbing PbSe nanocrystals attached to highly conducting single graphene sheets. The bandgaps of both PbSe and graphene can be altered by adjusting their dimensions and morphologies, which allows for substantial control over charge transfer in these nanocomposite materials. REU students will work to synthesize PbSe nanocrystals such as the “nanostars” shown in the figure below and will explore the chemical attachment of these systems to individual graphene sheets. Further, they will construct simple device architectures to evaluate the light-harvesting efficiencies of these nanocomposite materials. Students working on this project will learn materials synthesis techniques, electron microscopy, Raman spectroscopy, and basic cleanroom fabrication methods.