Three Areas of Research Focus
CO2 Conversion to Liquid Fuels
There is a clear demand to find new and efficient ways to decrease net CO2 emissions while converting it to a fuel. Solid state electrolysis, using electricity from renewable sources such as solar, wind, and biomass, has been proven to be a viable approach to electrochemically convert steam and CO2 to produce hydrogen or syngas (CO+H2).
Syngas can then be converted to hydrocarbons using the Fischer-Tropsch process. Another viable pathway to hydrocarbon fuels is the hydrogenation of CO2. This RT will integrate USC expertise in the area of electrochemical engineering and functional materials, with our expertise in nanoscale synthesis of heterogeneous catalysts and materials engineering. Furthermore, computational studies provide a deeper understanding of the materials and surface chemistry issues critical to the proposed applications.
By exploring the different CO2 conversion approaches (e.g., room temperature versus elevated temperature, non-precious metal versus precious metal catalysts), students will be trained in interdisciplinary skills in electrochemistry, materials science and engineering, surface and catalysis science, as well as nanomaterials fabrication and characterization.
Catalytic Conversion of Biomass
In response to dwindling worldwide petroleum resources, our nation’s overdependence on imported oil, and global climate change, Congress passed the Energy Independence and Security Act (EISA) in December 2007. It aims for 20% replacement of imported oil by 2022 by mandating the development of domestically produced renewable fuel. Meeting this goal will help achieve energy independence, reduce greenhouse gas emissions, and create jobs for rural America. Biofuels (i.e., liquid fuels derived from biomass feedstocks) show promise for helping meet this goal. Nanostructured bimetallic and/or bifunctional catalysts will be at the cutting edge of materials with high impact in this area. The research in this thrust will take advantage of USC’s unique expertise for the rational synthesis of nanostructured catalysts. Catalytic reactions representative of several core biomass conversion processes will be targeted. In the area of catalyst and materials synthesis, organometallic clusters, dendrimer-metal nanocomposites, and surfactant templating, will be coupled with more scalable approaches such as strong electrostatic adsorption (SEA), to prepare multimetallic nanoparticles on high surface area supports (e.g., oxides, carbon, zeolites) and on flat model supports (e.g., single crystal metal oxides, graphene). Such materials will be evaluated in flow and batch reactor systems and in high temperature solid oxide fuel cells. Characterization of catalyst surfaces and surface reactions via spectroscopy and through computational studies will reveal mechanistic details that guide materials synthesis. Through these research projects, IGERT trainees will gain experience in catalyst synthesis, materials characterization, surface spectroscopy, reactor kinetics, and mechanistic catalysis.
Voltaic Conversion of Solar Energy
Thin film solar cell technology has advanced significantly over past decades reaching a record efficiency of 20.1% for CuInGaSe2 (CIGS) and 17.3% for CdTe based solar cells. However, supply limitations for In, Ga and Te are expected to limit production capacity of these chalcogen-based technologies to <100 GW/yr, whereas demand for TW-scale production is predicted by 2050. This RT is therefore focused on four pillars – synthesis/characterization/theory/device – to achieve a complete picture of thin film PV technology that can develop non-toxic sustainable solar cells with high photo-conversion efficiency and improved life-time. Activities will involve the synthesis of light absorbing functional Cu2ZnSnS4 (CZTS) nanomaterials, and development of a thin-film deposition technique using stacked metal layers. Conducting electrode layers, such as Zn-based transparent conducting oxide and graphene, will be developed along with band-matching nanocrystal window contacts. Materials emerging from these investigations will be used to fabricate and test “next generation” thin-film solar cells. Research will also be conducted to understand ultra-fast charge transport properties at different junction interfaces and to provide a deeper understanding of charge transport and materials properties using mathematical modeling and computation. Through these collaborations, IGERT students will experience interdisciplinary programs connecting material synthesis, characterization, nanoscience, surface science, and molecular engineering to solar cell fabrication and testing. Theory and modeling provides deeper understanding and linkage among interfacial, photo-physical, and charge transport properties.