Researchers from the University of Cambridge have reached this 'milestone' by splitting water into hydrogen and oxygen.

They did this through using a technique called semi-artificial photosynthesis that is based on the same process plants use to convert sunlight into energy.

Hydrogen, which is produced when the water is split, could potentially be a green and unlimited source of renewable energy.

Researchers did this by reactivating hydrogenase, an enzyme present in algae, that can reduce protons into hydrogen.

Oxygen is produced as a by-product of photosynthesis when the water absorbed by plants is 'split'.

It is one of the most important reactions on the planet because it is the source of nearly all of the world's oxygen.

Researchers used natural sunlight to convert water into hydrogen and oxygen using a mixture of biological components and manmade technologies. 

Academics at the Reisner Laboratory in Cambridge's Department of Chemistry developed the new technique of solar-driven water-splitting.