With the predicted shortage of oil and the problems of climate disruption, the hydrogen appears as an alternative fuel with great potential in the eyes of some industry. Indeed, its combustion in a pile or a combustion engine emits only water. Furthermore, it is a very abundant element, since it can be produced from water. However, the high cost of production, and its storage form of hydrogen gas at high pressure, are all obstacles to the introduction into society of this technology. The process of AIST would reduce the cost of producing hydrogen.

A process for producing hydrogen is electrolysis of water under the influence of an electric current, water is decomposed into oxygen and hydrogen. The AIST has coupled the process of electrolysis to the decomposition of water by photocatalysis. The two processes are linked by the use of redox couple iron (Fe3 + / Fe2 +). Using it as an intermediate lowers the voltage needed for electrolysis of 1.6 V to 0.8 V.

Researchers use as photocatalyst powder tungsten trioxide (WO3) whose particle surface was treated with cesium (Cs), which increases their ability to absorb light. They eliminate the unwanted ions Cs + by a second treatment with iron sulfate (II) (FeSO4). Researchers have thus found that the rate of oxygen production by photocatalysis from 18 micro-mol / h of pure WO3 at a value between 113 and 117 micro mol / h of WO3 treated with Cs, and 196 micro-mol / h after cleaning FeSO4.

After treatment, the rate of absorption of visible light (for a wavelength of 420 nm) is 19% against 0.4% for a photo-catalysis with WO3 untreated. Subsequently, the researchers hope to use the whole light of wavelength below 480 nm to increase the conversion rate of 0.3% to 2.4%. Moreover, they continue their quest to find another catalyst that could absorb all wavelengths below 600 nm and thus proceed to a conversion rate of 7.5%.