Bilayer Dye Aids Solar Water-Splitting

By mimicking lipid bilayer membranes found in living cells, researchers have designed a cathode for water-splitting solar cells that remains stable in strongly acidic conditions (J. Am. Chem. Soc. 2016, DOI: 10.1021/jacs.5b07723). Photovoltaic cells are widely used to produce electricity from sunlight. By modifying the cell design, scientists can harness the current generated to split water, thereby producing clean-burning hydrogen. Dye-sensitized solar cells, which contain a light-absorbing dye anchored to semiconductor particles, are widely studied for power applications, but not for water-splitting. The problem is, the dye-based cells decompose in water, especially in acidic conditions, which otherwise would be helpful for boosting the kinetics of hydrogen production. So Ohio State University’s Yiying Wu and coworkers have come up with a dye that forms a protective lipid-bilayer-like structure. At one end of the molecule, a canopy of long-chain alkyl groups shields the acid-sensitive interface between nickel oxide particles and triphenylamine electron-donor units. At the other end, peryl­enemonoimide electron-acceptor units rise above the canopy, where they transfer charge to the acidic electrolyte and generate hydrogen. In a test run, the system produced high levels of hydrogen without degrading for a record-setting 16 hours.