The goal is to design a bio-inspired system that can produce fuels like methanol or hydrogen directly from carbon dioxide or water, respectively, using renewable solar energy. To replicate one of the important steps in natural photosynthesis, Muckerman uses molecular complexes containing the metal ruthenium as catalysts to drive the conversion of water into oxygen, protons, and electrons. Specifically, Muckerman’s group has set out to determine the electronic activity of a catalyst recently developed in Japan. Unlike previous ruthenium catalysts, which have a very short life, this catalyst has quinone ligands attached to each of its ruthenium centers. These electron-accepting molecules appear to make the catalyst very active and stable. The challenge is to determine exactly how the catalyst works.
“It was a controversial result,” said Muckerman, who compares the lab results to calculations based on theory. “I believe that the reaction occurs by ruthenium-mediated electron transfer from water molecules bound to the metal centers to the quinone ligands. These electron transfers are initiated by proton transfers from the bound water moieties to the aqueous solution. The ruthenium atoms maintain the same charge state during the entire catalytic cycle, indicating that this catalyst works in a totally different way than the other catalysts.”
This result could open up a new direction for designing future catalysts. Muckerman will present further details during his talk at 1:20 p.m. Eastern Time in the room 160C of the Boston Convention and Exhibition Center.-DOE/Brookhaven National Laboratory
