Water-Oxidation Catalysis by Cobalt Polyoxometalates vs Anion-Stabilized Cobalt-Oxide Nanoparticles: A Critical Comparison En Route to the True, Superior Catalysts

Colorado State University, Fort Collins CO

Investigators

Abstract

With this award, the Chemical Catalysis Program in the Chemistry Division is funding Richard G. Finke of Colorado State University for research aimed at determining the best catalysts for the extraction of energy from sunlight. Conversion of solar energy to usable gaseous or liquid fuels is a central scientific challenge to the development of a secure, sustainable energy future. One promising and well-studied approach uses solar energy to split water into its constitutive components of hydrogen and oxygen. In using this approach, scientists are mimicking one of the basic processes of life in which plants extract the energy from light through photosynthesis. In the laboratory, solar energy is used to split a water molecule with the help of a catalyst that can release the water's hydrogen atoms from its oxygen atom, producing clean-burning hydrogen fuel plus a safe and useful byproduct, oxygen gas. This project is focused on the development of efficient water-splitting catalysts made from cobalt. These catalysts are some of the most promising ones available, due to their abundance, low-cost and superior water-splitting ability. The work is focused on more precisely understanding how these catalysts work and, in the process, is leading to the development of better and more efficient catalysts. The project is having a broad impact through the development and refinement of a potentially crucial energy technology and also through the training of a future generation of scientists. The research is considering, in particular, homogeneous cobalt polyoxometalates as water-splitting catalysts. The investigators are, first, focused on determining the nature of the true catalytic species, since prior results from their lab indicated that a heterogeneous cobalt oxide was actually the dominant catalyst. Current research involves an alternative hypothesis that heterogeneous cobalt-oxide nanoparticles are the true catalysts, formed from cobalt polyoxometalates under the catalytic operating conditions and that those heterogeneous cobalt-oxide nanoparticles are a longer lived, more active and therefore superior class of water-oxidation catalysts. The ongoing research is helping to sort out these details and, therefore, contributing to the development of new and better catalysts for the splitting of water using solar energy.