(5by) Chemical Energy Conversion: Molecular Approach towards the Discovery of Efficient and Environmentally Friendly Heterogeneous Catalysts and Electro-Catalysts

My objective is to utilize cutting edge tools, including various spectroscopies, microscopies and quantum calculations to study processes at the gas/solid and liquid/solid interfaces. The aim of these studies is the development of a molecular knowledge-base that can be utilized to develop efficient and environmentally friendly materials for chemical energy conversion. To illustrate the overall approach I will present some on my recent efforts.

Steam reforming is widely utilized to convert hydrocarbon fuels into hydrogen and oxygenated carbon species. This process is important not only for the catalytic hydrogen production but also for direct electrochemical reforming over high temperature fuel cells such as Solid Oxide Fuel Cells (SOFCs). One of the main problems associated with the process is that the commonly used reforming catalysts, such as Ni supported on oxides, deactivate due to carbon poisoning.

We have utilized Density Functional Theory (DFT) calculations to study carbon chemistry on Ni and Ni-containing alloys. [1,2] The main objective of these studies was to develop molecular insights regarding carbon poisoning on Ni and to utilize this molecular information to identify possible carbon-tolerant alternatives to Ni. The DFT calculations indicated that the Ni surface alloys should a have lower tendency toward carbon poisoning than monometallic Ni. These findings were corroborated by in-house reactor studies and various spectroscopic and microscopic studies. [2,3] The potential utility of these alloy materials as carbon-tolerant SOFC anodes was experimentally demonstrated.

Furthermore, we have also utilized electron energy-loss near-edge spectroscopy (ELNES), in-situ x-ray photoelectron spectroscopy (XPS) and augler electron spectroscopy (AES) to measure the electronic structure of supported monometallic Ni and Ni alloy catalysts. We have demonstrated that the measured electronic fingerprints can be uniquely related to the chemical activity of these materials. Our observations are in accord with the d-band theory of Norskov and Hammer.

References

[1] E. Nikolla, A. Holewinski, J. Schwank, S. Linic, J. Amer. Chem. Soc, 128 (2006) 11354.

[2] E. Nikolla, J. Schwank, S. Linic, J. Catal. 250 (2007) 85 .

[3] E Nikolla, J. Schwank, S. Linic, Catal. Today, (2008) in press.