Hydrogen is often touted as an environmentally-friendly fuel – but the gas is only as clean as the method used to make it. Now, however, scientists have invented a solar-powered method for splitting water which they claim is the most efficient to date¹.

Michael Grätzel and colleagues from the Federal Polytechnic School of Lausanne, Switzerland, hope that their method could one day provide a cheap and efficient technology to produce abundant hydrogen using the Sun’s rays.

When water is split into its component elements, hydrogen is produced at the cathode of an electrochemical cell, while oxygen bubbles from the anode. It is this latter half that Grätzel’s team have focused on, using a new kind of photoanode made from the iron oxide haematite (Fe2O3).