Hybrid Photocatalyst Produces H₂Rapidly

Nature’s photosynthesis machinery can be combined with inexpensive synthetic transition-metal-based catalysts to yield a complex that rapidly produces hydrogen from water in the presence of light (J. Am. Chem. Soc., DOI: 10.1021/ja206012r). The study, conducted by researchers at Argonne National Laboratory, demonstrates a strategy for synthetically enhancing properties of photosynthesis systems to produce fuels from sunlight. Various strategies have been tried previously to exploit photosynthesis for fuel production. Examples include synthesizing mimics of natural metal complexes and coupling photosynthesis proteins such as photosystem I (PSI) with enzymes or with platinum nanoparticles. Earlier this year, Argonne’s Lisa M. Utschig and coworkers showed that a PSI-platinum nanoparticle complex rapidly liberates H₂ from water (C&EN, Jan. 31, page 45). Now, a team led by Utschig has replaced the nanoparticles with cobaloxime, a molecular catalyst based on the more abundant and less expensive metal cobalt. The self-assembling PSI-cobaloxime complex produces H₂ at about half the rate of the most active platinum nanoparticle system, but at rates up to 200 times faster than other artificial photosynthesis strategies.