Mullins Group: Energy Trailblazers

Mullins' lab studentCreating fuel from sunlight sounds like something out of a sci-fi movie depicting technology of the future, but Professor Mullins and his team are working to make this concept a reality.  Trailblazers in energy research, the Mullins Group is also studying materials in lithium-ion batteries for portable electronic devices and electric cars as well as catalytic materials for energy related processes.

All three projects could contribute to reducing the nation’s dependency on oil and lower carbon emissions to avert major effects of climate change. As gas prices climb and global temperatures rise, capturing renewable energy from the sun to generate clean fuel or power is a rewarding venture for researchers.

Mullins’ team is working on materials and processes that will utilize sunlight to generate a reaction that splits water into hydrogen and oxygen. Safely separating the two gases enables hydrogen to be employed as a fuel or chemical feedstock. Materials and processes are currently available to use sunlight to create fuel, but not efficiently or cheaply enough to be viable. The key is finding a material capable of absorbing and utilizing light effectively and coupling it together with an efficient catalyst for oxidizing and reducing water. The material must also be sturdy and cheap.  In some ways, the material will mimic the photosynthetic machinery of plants to create energy.  The idea is to use the material in panels that will likely cover many square miles in order to produce enough hydrogen for industrial use.

Working with veteran chemist Allen Bard, Mullins’ team examines the effects of nanostructuring on complex materials identified by Bard’s team.  The Mullins Group experiments with the materials’ structure and looks for nanformations that improve the efficiency of a given compound.   The best materials are then tested in prototype systems.  If Mullins and Bard can achieve 10 percent efficiency with a material that is stable for 10 years and costs a couple dollars per square meter, they could be competitive.  Currently, their material of focus is bismuth vanadium oxide, doped with some tungsten and molybdenum, which is performing at 1 percent efficiency.

The Mullins Group also identifies new materials with favorable structures for use in advanced lithium-ion battery electrodes.  Carbon or graphite is typically used in commercial lithium-ion battery anodes, but safety issues persist. Safety for electric vehicles is of paramount importance, as is energy and power density.

The team is working with renowned colleague and chemical engineering research professor Adam Heller to improve the performance of silicon and other materials anodes in lithium-ion batteries which will reduce charge time, increase long term cyclability, and improve safety. The group recently published results in Chemical Communications regarding their evaluation of a silicon nanoparticle-based anode employing a halogenated electrolyte, which performed extremely well. Better lithium-ion batteries will provide cheaper power sources and a larger driving range for electric cars.

The Mullins Group is also involved in surface chemistry and catalysis research and has just begun collaborating with Adam Heller on direct catalytic processes regarding the conversion of natural gas into higher value products.  Although the group has much experience in ultra-high vacuum studies of surface chemistry on well-characterized samples, catalytic research at atmospheric pressure over high surface area materials, similar to those used industrially, is a new line of investigation for the group.

Mullins holds the Z.D. Bonner Professorship and his group consists of 14 graduate students and 12 undergraduates dedicated to advancing renewable energy sources for the benefit of society.

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