Highly Efficient Photoelectrochemical (PEC) Device (IMAGE) California Institute of Technology Caption A highly efficient photoelectrochemical (PEC) device uses the power of the sun to split water into hydrogen and oxygen. The stand-alone prototype includes two chambers separated by a semi-permeable membrane that allows collection of both gas products. Credit Lance Hayashida/Caltech Usage Restrictions With attribution License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.