Photoreduction of Carbon Dioxide

For electricity and power, much emphasis has been placed on photovoltaic cells and together with many other alternatives, technologies are in place and developing to replace fossil fuel based power plants.  For fuel, needed for transportation and also in many industrial sectors, our progress is less advanced and significant scientific hurdles need to be overcome. In essence, in order to utilize the solar energy as a fuel it must be captured and then stored. In the research in our group we are considering a less studied catalytic chemical approach to the recycling of CO2 to fuel. More specifically, we are interested in the direct use of solar photochemical energy whereby the photoenergy is initially stored as chemical energy in the two-electron reduced product, carbon monoxide (CO).

Green Chemistry

The realization in the latter part of the 20th century that many syntheses practiced on a large scale were detrimental to the environment led to a movement towards reshaping the science of organic synthesis. The problems are particularly acute in the area of oxidation chemistry. Thus, the approach taken in this research is motivated or “pulled” by societal considerations that demand environmentally benign and sustainable solutions

Activation of Molecular Oxygen

Molecular oxygen is kinetically quite stable towards reaction at room temperature because of its triplet ground state and strong oxygen-oxygen bond.  On the other hand the thermodynamic tendency for the reaction of O2 is combustion, that is to form carbon dioxide (CO2) and water (H2O). Thus, hydrocarbons typically react with O2 via a complex free-radical pathway termed autooxidation.  These reactions are usually not selective and often have little synthetic utility.  In order to overcome this limitation, in our group we are developing catalysts that catalyze reactions by new reaction pathways. Catalysis is used both to lower the activation energy of the reaction and to change the chemoselectivity of the reaction.