Weber Research Group ^{Ion Spectroscopy}

Overview

The Weber group will characterize the infrared spectra of molecular catalysts for the reduction of carbon dioxide, as well as other species relevant for the catalytic cycle involving such catalysts. The ionic catalysts under study are generated by electrospray ionization, and their complexes with carbon dioxide, proton donors, and solvents are prepared in a series of temperature controlled ion traps. The target ions are irradiated with pulsed infrared light from a widely tunable infrared light source.  Photon absorption and subsequent fragmentation of the target ions is used to measure their vibrational spectra.  These spectra will yield information on the structures and intra-/intermolecular forces governing the catalysts. Additionally, the Weber group will characterize the interaction of these complexes with proton donors and solvent molecules. The spectra will allow mechanistic insight into the chemistry at play in electrochemical conversion of carbon dioxide into other, more valuable molecules.

 

Intellectual Merit         

 The generation of a carbon neutral, sustainable energy economy has been recognized by many as one of the most important new technologies to be developed in the near future. Artificial photosynthesis, i.e., the (photo)electrochemical conversion of carbon dioxide into chemically useable fuels is a very promising approach to attain this goal. In order to develop cost-effective catalysts, the molecular-level mechanisms of the steps in the catalytic cycle need to be understood. 

The complexity of reactive solutions presents one of the main impediments to gaining deeper insight into the properties of complexes of catalysts and carbon dioxide. The mixture of many components in solutions under turnover conditions is difficult to analyze, and the detailed properties of individual species often remain elusive. Many molecular catalysts for carbon dioxide reduction and the intermediates in the respective catalytic cycles are ions. This allows selective preparation and mass spectrometric isolation of the relevant species and circumvents the speciation problem. Mass spectrometric preparation of ions from solutions in concert with laser spectroscopy is a powerful and elegant approach to investigate the molecular properties of catalysts, their activated complexes with carbon dioxide, and the effect of proton donors and solvent molecules on these properties.  A comparison of experimental data with quantum chemical predictions will permit benchmarking of computational approaches to describe catalysis. This will allow to gauge the applicability and accuracy of current quantum chemistry methods towards a predictive characterization of carbon dioxide reduction catalysts.

Broader Impacts:   

The chemistry studied in the proposed work will have significant benefit for chemical energy science and chemical engineering, as well as other fields of science. Given that many areas of technology will continue to depend on the use of chemical fuels, environmental as well as economic and geopolitical pressures call for the development of fuel sources independent from fossil fuels. Molecular level insight into artificial photosynthesis and the related catalytic cycles for solar fuel generation is a necessary first step to develop new and better catalysts for the production sustainable chemical fuels.

Much of the proposed work will be carried out by graduate student researchers. The proposed work will therefore contribute to the education of the next generation of scientists who will be trained in a broad range of experimental and computational techniques.

Moreover, the Weber group will develop an educational, web-based simulation of catalytic cycles for carbon dioxide reduction and water oxidation catalysis.  This simulation will transport the focal point of the laboratory research into the classroom and aim to enhance student understanding of the kinetics involved in solar fuels catalysis.  This component of the proposed work will result in an interactive teaching tool, which will be freely available to any instructor.

The PI will be involved in the highly successful CU Wizards outreach program. This is a continuing Saturday morning lecture series that treats topics in astronomy, chemistry, engineering, and physics, and is intended primarily for students in grades five through nine. The PI contributes an interactive lecture to this series with many experimental demonstrations, introducing the audience to the world of buoyancy and water displacement.