Nature Chem. http://doi.org/v7m (2014)

Credit: NATURE PUBLISHING GROUP

The fabrication of artificial photosynthetic systems by taking inspiration from complex cellular structures, for example, from plant chloroplasts, offers the opportunity to produce light-harvesting materials with energy conversion properties. With this in mind, Samuel Stupp and colleagues prepare a hydrogel scaffold that incorporates light-absorbing chromophores and nickel-based catalysts and show its capability for photocatalytic hydrogen production. The hydrogels are formed from the addition of salts or the positively charged catalyst to aqueous solutions of supramolecular ribbons of anionic amphiphilic chromophores. The screening effect of the positively charged catalyst promotes the two-dimensional crystallization of the amphiphilic chromophores and results in strong electrostatic coupling between the chromophores and catalyst. In the presence of ascorbic acid, which acts as a proton source and sacrificial electron donor, the photocatalytic production of hydrogen is observed. Light, catalyst, ascorbic acid and the amphiphilic chromophores, together with the hydrated state of the gel, are all required for hydrogen evolution. This co-localization of light-harvesting moieties and redox catalysts within a hydrogel represents an exciting step forward for bioinspired soft materials.