Scientists at CSIR have developed an artificial leaf that absorbs sunlight to generate hydrogen fuel from water. The invention may provide clean energy for powering eco-friendly cars in the future. It is an ultra-thin wireless device that mimics plant leaves to produce energy using water and sunlight. The device is of an area of 23 square centimetres and could produce 6 litres of hydrogen fuel per hour.
Hydrogen burning gives energy and water as a side product. This underscores its importance and relevance to the present day world. India is blessed with plenty of sunlight through the year that is not exploited significantly to produce energy or hydrogen.
The device consists of semiconductors stacked in a manner to simulate the natural leaf system. When visible light strikes the semiconductors, electrons move in one direction, producing electric current. The current almost instantaneously splits water into hydrogen which makes it the main by product.
At present, hydrogen is produced from fossil fuels by steam reforming and in this process emits a large amount of carbon di-oxide (CO2) – a green house gas that promotes global warming. In not so distant future cars fuelled by hydrogen generated from the artificial leaf process could start running on the roads.
In the recent past, automakers have been offering cars powered by hydrogen fuel cells. To improve the light-absorbing efficiency of the artificial leaf gold nanoparticles, titanium dioxide and quantum dots were used. Quantum dots are semiconductor crystals of nanometre dimensions with properties that depend on the size of the dots. When exposed to sunlight for 25 hours, the device retained its efficiency. The cell does not need any external voltage and performs better than existing solar cells, he said.