EAGER:CAS-Climate: Novel Non-Precious Metal Catalysts for Oxygen Reduction Reaction

University Of Arkansas At Pine Bluff, Pine Bluff AR

Investigators

Abstract

With the support from the Chemical Catalysis Program in the Division of Chemistry, Daoyuan Wang of the University of Arkansas at Pine Bluff and Anindya Ghosh of the University of Arkansas at Little Rock are developing new catalysts based on earth-abundant metals for fuel cell applications. Most commercially available hydrogen-oxygen fuel cells consist of expensive platinum (Pt) anodes and cathodes. Thus, a significant motivation for preparing suitable replacements for the Pt-based electrodes exists. The Wang and Ghosh collaborative team will synthesize non-precious metal complexes supported on multi-walled carbon nanotube and graphene materials, and evaluate them as catalysts for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). This research is anticipated to impact renewable energy and fuel cell technology, with important implications for sustainability. Underrepresented minority students in science and engineering will actively participate in the research. The educational program will include outreach activities to surrounding schools and educational centers in Arkansas to promote green chemistry and sustainable energy to teachers, students, and the general public. This project aims to develop new non-precious metal catalysts for the ORR reaction, with the catalysts derived from metal complexes containing tunable amide ligands. The collaborative research teams of Wang and Ghosh will design ligands that will provide tunable coordination environments for the stabilization of the metal centers in unusual oxidation states and favoring oxygen reduction. The amide-based complexes will be designed to be either square planar or to contain weakly bound ligands in different geometries, to allow for oxygen coordination to the metal center for its facile reduction while enhancing higher current density and lower overvoltage. The metal complexes will be supported on carbonaceous nanomaterials. These supported systems will then be coated with inexpensive and bioinspired polymers such as polydopamine and its derivatives, and evaluated for their potential to provide enhanced oxidative and hydrolytic stability to the metal complexes over a wide pH range and to significantly improve ORR activity. Varying the ratios and/or types of the individual components of this three-component system (metal complex, carbonaceous support, polymer coating) will be performed and the results evaluated experimentally and electrochemically. An emphasis will be placed on understanding the structure of the active sites of the catalysts and the mechanisms of the ORR enabled by these new systems. The research activities and their relationship to environmental sustainability will be incorporated into the planned outreach activities. 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.