The water splitter is made from the relatively cheap and abundant metals nickel and iron. It works by sending an electric current from a single-cell AAA battery through two electrodes.

"This is the first time anyone has used non-precious metal catalysts to split water at a voltage that low," chemistry professor and lead researcher Hongjie Dai says. "It's quite remarkable, because normally you need expensive metals like platinum or iridium to achieve that voltage."

The technology has huge potential as a source for powering hydrogen fuel cells, long held as a likely successor to gasoline. Unlike gasoline combustion, which emits large quantities of the greenhouse gas carbon dioxide, fuel cells combine stored hydrogen gas with oxygen from the air to produce electricity, leaving only water as a byproduct.