Chinese and Swiss scientists have unraveled the secret of why a catalyst they discovered could split water into hydrogen and oxygen to be used as a form of clean fuel.

Xinhua reported that the joint study showed that the “water-splitting” catalyst had a “bifunctional mechanism,” a cooperative action of two phase-separated components of iron and nickel oxides. The finding was published this week in the latest edition of scientific magazine ACS Central Science.

Water splitting is the chemical reaction in which water is broken down into oxygen and hydrogen. Efficient and economical photochemical water splitting would be a technological breakthrough that could underpin a hydrogen-driven economy.

No practical version of water splitting has been demonstrated, but the two component reactions (H2 production and O2 production) are well known. The reverse of water splitting is the basis of the hydrogen fuel cell.

Song Fang at the Shanghai Jiaotong University and Hu Xile’s lab at Ecole Polytechnique Federale de Lausanne in Switzerland discovered the nickel-iron-oxide catalyst three years ago, which is robust, easy to synthesize and open to industrial applications. The catalyst is very active to start the oxygen evolution reaction, arguably the most difficult process in water splitting.

Identifying ideal materials that can split water has been a long-standing problem in renewable-energy storage.

Because hydrogen is a clean fuel, researchers worldwide are pouring a lot of effort into developing water-splitting catalysts.

The newly discovered catalyst is now proved to be an efficient electrolyzer that could work under industrial conditions with significantly less electricity consumption, according to the study.

The electrolysis of water is a simple method of producing hydrogen. A low-voltage current is run through the water and gaseous oxygen forms at the anode while gaseous hydrogen forms at the cathode. Typically the cathode is made from platinum or another inert metal when producing hydrogen for storage.