Wireless solar water splitting using silicon-based semiconductors and earth-abundant catalysts

We describe the development of solar water-splitting cells comprising earth-abundant elements that operate in nearneutral pH conditions, both with and without connecting wires. The cells consist of a triple junction, amorphous
silicon photovoltaic interfaced to hydrogen and oxygen evolving catalysts made from an alloy of earth-abundant metals and a cobalt|borate catalyst, respectively. The devices described herein carry out the solar-driven water
splitting reaction at efficiencies of 4.7% for a wired configuration and 2.5% for a wireless configuration when illuminated with 1 sun of AM 1.5 simulated sunlight. Fuelforming catalysts interfaced with light-harvesting semiconductors afford a pathway to direct solar-to-fuels conversion that captures many of the basic functional elements of a leaf.