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Efficient solar water splitting

Using a simple solar cell and a photo anode TU Delft scientists were able to store nearly five percent of solar energy chemically in the form of hydrogen.

Artificial photosynthesis, the use of sunlight to split water into hydrogen and oxygen, allows solar energy to be stored in the form of hydrogen. Usually expensive solar cells or costly semiconductors are used for this. But there is a cheaper alternative, or so researchers of the faculty of Applied Sciences and the Photovoltaic Materials and Devices Laboratory believe.

Together with colleagues of the Helmholtz-Zentrum Berlin for Materials and Energy the Delft scientists combined an inexpensive solar cell with a photo anode made of the light-sensitive metal oxide Bismuth vanadate (BiVO4), a very cheap material used as a pigment in the paint industry. Nearly 5 per cent of the energy in the incident sunlight was stored in the hydrogen produced. The findings were published on the 29th of July online in Nature Communications.

Experiments were performed before with bismuth vanadate, Professor Bernard Dam (AS faculty) says in a press release. “But the level of efficiency achieved was relatively low. The essential improvement now made by PhD student Fatwa Abdi is the addition of a so-called concentration gradient of tungsten atoms to the bismuth vanadate. They dramatically improve the efficiency of the photo anode. We have reached a yield of almost 5 per cent. For this type of set-up, that is a record. And we believe that an efficiency of 10 per cent can eventually be achieved.”

‘Efficient solar water splitting by enhanced charge separation in a bismuth vanadate-silicon tandem photoelectrode’ Fatwa F. Abdi, et., al. Nature Communications, 29 July 2013.

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