Sustainable generation of fuels through the catalytic conversion of CO₂ is an area of research that has the potential to enhance national energy security while simultaneously providing a mechanism to minimize direct CO₂ emissions. Previous studies on CO₂ photoreduction to fuels have utilized TiO₂-based catalysts. A major challenge that exists with utilizing TiO₂ as a photocatalyst for CO₂ photoreduction is the fast recombination of electron-hole pairs which are formed by light irradiation. Electrons are needed to generate products via reduction of CO₂. Efforts to minimize charge recombination are critical for enhancing product formation. Despite past efforts at modifying the TiO₂-based catalysts using both metal and non-metal modifiers, published data shows relatively low production rates for useful products. Typical products include CO and valuable fuel products such as CH_{4 and CH3OH. Several of the catalysts resulted in the formation of multiple products, resulting in the need for gas separation technologies when the catalyst is implemented in a real-world scenario.}

Preliminary experiments in the laboratories of Professor Jean Andino at Arizona State University have shown promise for a composite catalyst of RGO-TiO₂, reduced graphite oxide and titania. The RGO can potentially assist in minimizing charge recombination when TiO₂ is activated by light, thereby making more electrons available for a surface CO₂ reduction reaction. A potential challenge with using reduced graphite oxide is whether the interlayer spacing would be sufficient to allow TiO₂ to reside between the RGO layers. A modified RGO structure with increased interlayer spacing would alleviate this concern. Moreover, if the modifier for the RGO is capable of selectively attracting CO₂ as compared to hydrocarbons, then this may allow for enhanced functionality. Published data show that CO₂ is strongly attracted to ionic liquids. Andino hypothesizes that an ionic liquid (IL) functionalized RGO-TiO₂ would result in the attraction of CO₂, sufficient charge separation within the TiO₂ (making electrons available for the CO₂ photoreduction reaction), and rejection of the produced hydrocarbons, such as CH₄, thus reducing separation needs.

Andino has performed preliminary work to synthesize the IL-RGO/TiO₂ catalyst and to test the characteristics of the catalyst for the reduction of CO₂ to hydrocarbons in the presence of water vapor. The DRIFTS studies showed the IL-RGO/TiO₂ catalyst appears to lead to the selective and fast formation of CH₄ in the absence of any CO. The CH₄ production rate from CO₂ photoreduction is more than 30 times higher than that which was published by any other research group. The results (taken in conjunction with literature data) suggest that the newly developed IL-RGO/TiO₂ catalyst produces CH₄ at a rate that is far superior to any other existing catalyst.

This is an ideal basis for this EAGER award. Researchers typically use GC techniques to quantify the data and not the DRIFTS IR spectroscopy technique. Furthermore the impact of oxygen presence on product yield needs to be known. The proposed EAGER award will provide the necessary data to confirm the observation and generate additional data to support a full investigation.

This EAGER is expected to have several broader impacts in the catalysis area and will broaden participation in the field. First, the data that will be generated will help to establish the usefulness of the IL-RGO/TiO₂ catalyst in the direct and selective generation of a valuable fuel (CH₄). This work could have significant impacts in the areas of national energy security and the control of CO₂ emissions. The proposed project would be used to partially fund two traditionally underrepresented chemical engineering graduate students. The experience of working on the proposed project that has a strong connection to society's grand challenges has already inspired these students, and is expected to help retain them in science and engineering. The expectation is that both students will make sufficient progress so that at least one peer-reviewed paper will be submitted and presentations made locally and also at annual meetings of either the American Chemical Society, the American Institute of Chemical Engineers, or the Air and Waste Management Association in 2013.