Graphene based all-weather solar cells may generate power from rain

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Various technical advancement in the field of Solar energy have made Solar cells the most efficient and affordable source of power generation but a big disadvantage still remains intact in the fact that solar cells produce no power when it is raining but a team of researchers from the Ocean University of China and Yunnan Normal University have now introduced a new approach for making an all-weather solar cell  that can generate electricity even during rains.

For the conversion of solar energy to electricity, the researchers  developed a highly efficient dye-sensitized solar cell and in order to allow rain to produce electricity as well, they coated this cell with a very thin film of graphene. 

All-weather graphene solar panels will generate energy from rain: The performance of solar cells is often dete...

— Ionics Energy (@IonicsEnergy) April 10, 2016

What is Graphene ?

Graphene is a two-dimensional form of carbon in which the atoms are bonded into a honeycomb arrangement. It can readily be prepared by the oxidation, exfoliation and subsequent reduction of graphite. Graphene is characterised by its unusual electronic properties: 

(i) It conducts electricity

(ii) It is rich in electrons that can move freely across the entire layer

In aqueous solution, graphene can bind positively charged ions with its electrons (Lewis acid-base interaction). This property is used in graphene-based processes to remove lead ions and organic dyes from solutions. This phenomenon inspired researchers to use graphene electrodes to obtain power from the impact of raindrops.

How Graphene produces electricity during rain ?

♦ Raindrops are not pure water. They contain salts that dissociate into positive and negative ions. The positively charged ions, including sodium, calcium and ammonium ions, can bind to the graphene surface. 

♦ At the point of contact between the raindrop and the graphene, the water becomes enriched in positive ions and the graphene becomes enriched in delocalised electrons. 

♦ This results in a double-layer made of electrons and positively charged ions, a feature known as a pseudocapacitor. The difference in potential associated with this phenomenon is sufficient to produce a voltage and current. 

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