Tuning Electrical Properties in GaN Nanowires for Optimization of Artificial Photosynthesis

Abstract

Technological advancements in a variety of renewables have given previously less prominent energy sources new potential. Hydrogen fuel cells have shown great overall potential, but limitations are primarily in the rate of hydrogen generation due to the sluggish speeds of the underlying reactions. Chemical reaction rates depend on a variety of factors, one of which being the activation barrier: the system must gain energy and exceed a certain energy to reach completion, and the barrier for the hydrogen-generation-reactions is particularly high. Catalysts are materials that when introduced to a system reduce this activation barrier and make certain reactions possible or faster without consuming the catalyst by creating an alternative reaction pathway that’s more efficient. The Mi Lab’s research focuses on utilizing certain materials to stimulate the hydrogen-generation-reactions, combining catalysts and nanomaterials to reduce the activation barrier and provide more energy to the system. This process, which the Mi group is calling Artificial Photosynthesis due to its utilization of the sun to increase the rate of hydrogen generation, has the overarching goal of acting as a renewable energy source to generate electricity for utilization in homes or buildings similar to the solar panels on North Campus. The underlying process takes energy from the sun to excite electrons in semiconductor nanotubes, and those electrons are funneled to a catalyst material to significantly increase the rate of the hydrogen redox reactions by increasing the concentration of reactants. The focus of this project is to observe the effect of temperature on the electron excitation and transport in semiconductor nanotubes. Temperature is one of the few parameters that can be controlled in these systems to optimize operating conditions. While we understand that temperature is a balancing act between excitation and lattice vibration, being able to specifically quantify these mechanisms is essential for application. We ran computer simulation using Materials Studio to predict the electrical material properties of GaN over a range of operating temperatures. By understanding and analyzing these results, we can identify the temperature conditions that are optimal for system operation.