Their study, selected as an American Chemical Society "Editors' Choice" that will be featured on the cover* of the Journal of Physical Chemistry C, provides a platform for developing revolutionary improvements in so-called artificial photosynthesis--a lab-based mimic of the natural process aimed at generating clean energy from sunlight.
Many artificial photosynthesis strategies start by looking for ways to use light to split water into its constituents, hydrogen and oxygen, so the hydrogen can later be combined with other elements--ideally the carbon from carbon dioxide--to make fuels.
To achieve water splitting, scientists have been exploring a wide range of light-absorbing molecules (also called chromophores, or dyes) paired with chemical catalysts that can pry apart water's very strong hydrogen-oxygen bonds.
The new approach uses molecular "tethers"--simple carbon chains that have a high affinity for one another--to attach the chromophore to the catalyst.
The tethers hold the particles close enough together to transfer electrons from the catalyst to the chromophore--an essential step for activating the catalyst--but keeps them far enough apart that the electrons don't jump back to the catalyst.
So, to give the system time for the water-splitting reaction to take place without the electrons moving back to the catalyst, you have to separate those charges," explained Brookhaven Lab chemist Javier Concepcion, who led the project.