A large increase in the efficiency of photocatalytic systems for the production of H2 has been reported by Karen Brewer and co-workers, Virginia Polytechnic Institute and State University, USA. The team use a [{(bpy)₂Ru(dpp)}₂RhBr₂]⁵⁺ photocatalyst which couples a Ru^II light absorber to a Rh^III electron collecting site in a single-component, supramolecular system. Supramolecular photocatalysts provide efficient intramolecular electron transfer pathways, eliminating the need for diffusional contact.

The catalyst works at room temperature, in basic pH, and under significant H₂ pressure. It produced 4-times more H₂ per absorbed photon than its rivals and could generate 20-times more H₂ before deactivation. It also demonstrates excellent long-term stability with prolonged use providing 820 mol of H₂ per mole of catalyst.

Image: (c) Wiley-VCH (DMA= N,N-dimethylaniline: bpy=2,2’-bipyridine; dpp=2,3-bis(2-pyridyl)-pyrazine)

• High Turnover in a Photocatalytic System for Water Reduction to Produce Hydrogen Using a Ru, Rh,Ru Photoinitiated Electron Collector
  Shamindri M. Arachchige, Ryan Shaw, Travis A. White, Vimal Shenoy, Hei-Man Tsui, Karen J. Brewer,
  ChemSusChem 2011.
  DOI: 10.1002/cssc.201000399