Research
Key research areas
Solar CO2 reduction. We are investigating combinations of semiconducting films for using sunlight to energize electrons sufficiently to covert carbon dioxide into reduced products that can serve as solar fuels or as green chemical feedstocks. Crucially, this is coupled with microbial processes for extracting electrons from organics in wastewater. Conventional solar fuels production use electrons taken from water molecules, which requires far more energy and requires multiple solar photons per electron. In contrast, extraction of electrons from wastewater organics requires much less energy and a single photon suffices to promote such an electron enough to react with CO2. Research involves identifying, synthesizing and optimizing materials that are good candidates for this process and combining materials to efficiently route extracted electrons to CO2 molecules in water while avoiding recombination (short-circuiting within the semiconductor) or side-reactions like hydrogen generation.
Zinc-based batteries. Zinc is a far more abundant and cheap material than lithium and stores twice as much charge per atom. But zinc structures tend to dissolve upon discharge, making it difficult to produce rechargeable zinc batteries. We are investigating ways to address this challenge using nanostructuring to confine dissolved zinc complexes, and porous coatings that allow hydroxide exchange but not the release of zinc or zincate ions. We have published an investigation of the initial reduction of zinc oxide nanorods using electrochemical and synchrotron X-ray techniques.
Measurements of photovoltaic panels. PV panels were subjected to mechanical impact or thermal stress and studied by combined methods including current–voltage, electrochemical impedance spectroscopy, and electroluminescence imaging to identify early signs of degradation. The results can be useful for managing large PV arrays, and for analysis and quality control in the course of designing and manufacturing panels.
Low-cost solar energy conversion. The early focus of this group was improving the dye-sensitized solar cell, a nanotechnology-based approach to solar energy conversion with facile deposition methods of low-cost materials. Efforts targeted improving electron transport using nanostructures such as zinc oxide nanorods and an aerogel of antimony-doped tin oxide as a transparent conducting support. Work also used platinum nanoparticles to catalyze redox regeneration of dye molecules with low overpotential losses.