And one of the most promising semiconductor materials for such a task is gallium phosphide (GaP), which can convert sunlight into an electrical charge and also split water. Unfortunately, the material is expensive, but researchers have now used a processed form of gallium phosphide to create a prototype solar fuel cell that not only requires 10,000 times less of the precious material, but also boosts the hydrogen yield by a factor of 10.

While conversion efficiencies of around 15 percent have been achieved by connecting an existing silicon solar cell to a battery to split water through electrolysis, this is an expensive option. GaP offers the potential of an all in one "solar fuel cell" and now researchers at the Eindhoven University of Technology (TU/e) and the FOM Foundation have demonstrated how nanowires made of GaP are effective for photoelectrochemical (PEC) conversion of solar energy to fuel.