Converting the excess carbon dioxide (CO2) produced by so many of society's activities to fuels and other useful materials requires an input of energy. Currently, decreasing the energy needed to accomplish this is recognized to be a highly challenging task. In this project, Drs. Liang-shi Li and Krishnan Raghavachari at Indiana University are investigating how to combine ordered carbonstructures known as nanographenes with transition metal atoms to make a new family of catalysts. These catalyze CO2 reduction, that is, they improve the energy efficiency of the conversion. This is being accomplished by a synergistic combination of the experimental efforts from the Li group and the computational modeling from the Raghavachari group. The study seeks a basic understanding of how the structures of the carbon materials determine the catalytic performance of the transition metal. More broadly, the work aims to provide design guidance for improved catalysts based on metal-containing carbon materials, thereby leading to renewable uses of carbon materials for environment- and energy-related applications, while providing a diverse range of educational opportunities for graduate and undergraduate students. Outreach to underrepresented groups include a summer research experience program with Prairie View A&M University targeting undergraduate students from that historically black university.
With funding from the Chemical Catalysis Program of the Chemistry Division, Drs. Liang-shi Li and Krishnan Raghavachari at Indiana University are developing well-defined nanographene-metal complexes (NMCs) and investigating their electrocatalytic activities for selective CO2 reduction. Specially, well-defined nanographene ligands form complexes with Re or Mn to analyze and optimize their performance for selective electrocatalytic CO2 reduction to CO. Because of their large conjugation size, the nanographenes can readily undergo multiple reductions, effectively storing the electrons for chemical transformations, and in preliminary work, NMCs (containing Re) have already been demonstrated to yield an onset CO2 reduction potential that is the lowest reported so far. With synergistic experimental and theoretical efforts, the necessary conditions for the NMCs to be activated to catalyze the CO2 reduction are investigated. With nanographene ligands of various sizes and functionalizations, a detailed understanding on catalytic mechanisms of the NMCs is sought for the design of energy efficient and stable electrocatalysts that contain earth abundant metals and can be made with simple methods. In a broader context, the project aims to establish the nanographenes as a new class of redox non-innocent ligands, for potential application to the development of transition metal catalysts for many classes of multi-electron reactions.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
