The exploratory research proposed is aimed at understanding from a fundamental science perspective why and how dual-phase mixed oxide-ion and carbonate-ion conducting membranes containing highly interconnected ionic channels exhibit superior CO2 transport characteristics.
Intellectual Merits
The key intellectual merit of the proposed research is centered on the unique parallel bi-ionic pathways model that extends the ionic transfer zones from triple-phase boundaries (3PBs) to double-phase boundaries (2PBs) and is complemented by the experiments of 1) identification of a new intermediate surface species with in-situ Raman spectroscopy and 2) verification of the bi-ionic transport model through an MC-flooded permeation cell. Specifically: o For the first time C2O5 2- polycarbonate ions are proposed as an intermediate surface species that are reduced by O2- at 2PBs of MC/oxide-ion conductor interface o Confirmation of the formation of CO3 2?(CO2)n containing strong CO bonds and structurally stable chainlike [CnO2n+1] moieties by successively binding the simple nucleophilic anion CO3 2? with several CO2s through in-situ Raman spectroscopy o Verification of the proposed bi-ionic transport model through MC-flooded surface blocking permeation cell
Broader Impacts
Discovering energy-efficient and cost-effective CO2 separation membranes is of prime importance to the development and deployment of CO2 capture technologies in existing fossil fueled power plants. This research has the potential to transform conventional wisdom in understanding ionic transport behaviors in heterogeneous systems, and ultimately lead to rationally designed high-performance ionic systems for a variety of energy applications. One example is the design of (CO2)n chainlike compounds such as solid polycarbonates CnO2n+1R2 (R=large-size group) for highly efficient large-scale CO2 scrubbing. Another example is the design of CnO2n+1H2, a class of potential candidates for high-energy density materials as they decompose exothermically into nCO2 + H2O products, but are locally stable because of the existence of substantial dissociation barriers.
Both graduate and undergraduate students including minority and underrepresented groups will play an active role in this research through clearly identified, focused research projects. The importance and potential impact of ongoing scientific advances in the area of CO2 capture and storage technologies will be disseminated to the general public via the annual "Edison Lecture Series" program of the College of Engineering and Computing at the University of South Carolina.
The aim of this EAGER project is to understand from a fundamental science perspective why and how a ceramic-carbonate hybrid membrane containing highly interconnected 3D ionic channels allows a fast CO2 transport under a chemical gradient. During the one-year period, we have the following research outcomes to report: Identified with in-situ Raman spectroscopy the existence of pyrocarbonate ion C2O52- as an active surface species involved in fast surface CO2 reduction reaction The new characteristic Raman bands for the C2O52- species are centered at 1,317 cm-1 and 1,582 cm-1 DFT calculations agree well with the experimental values Established a new charge-transfer model based on C2O52- surface species to interpret the fast CO2 transport through the bionic ceramic-carbonate hybrid membranes For the first time, the fast CO2 transport in ceramic-carbonate hybrid membranes is delineated to be attributed to extended reactive sites from three-phase boundaries to two-phase boundaries The broader impact of the project is demonstrated by both the academic achievements and educational activities. The unequivocal elucidation of the parallel bi-ionic transport mechanisms has demonstrated a new scientific advancement in fast multi-ionic transport in heterogeneous systems, and serves as the foundational knowledge to design more efficient complex energy material systems. In addition, the project has produced four journal publications, one conference presentation and one patent disclosure. The project has also hired one female undergraduate student (Ms Whitney Tharp) from the department of Mechanical Engineering during the summer of 2013.
