Researchers at the University of Bath are developing new solar cells that use light energy directly to split water.
Most solar cells currently on the market are made of silicon, but a new generation of cells are being developed using a material called perovskites that have the same 3D structure as calcium titanium oxide.
These are cheaper to make, thinner and can be easily printed onto surfaces and also produce a higher voltage than silicon cells. This is really helpful for generating hydrogen by splitting water.
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Unfortunately, perovskite cells are unstable in water, so the team at the Centre for Sustainable Chemical Technologies created a waterproof coating from graphite.
They tested the waterproofing by submerging the coated perovskite cells in water and using the harvested solar energy to split water into hydrogen and oxygen. The coated cells worked underwater for 30 hours – ten hours longer than the previous record.
“Perovskite solar cell technology could make solar energy much more affordable for people and allow solar cells to be printed onto roof tiles. However at the moment they are really unstable in water – solar cells are not much use if they dissolve in the rain,” said Dr Petra Cameron, Senior Lecturer in Chemistry.
The reason the cells failed was the glue sandwiching the coat to the cells. Using stronger glue could help the cells operate for longer underwater.
The higher voltage from the cells is still not enough needed to split water using solar cells alone, so the team is adding catalysts to reduce the energy requirement needed to drive the reaction.
“Currently hydrogen fuel is made by burning methane, which is neither clean nor sustainable,” said Isabella Poli, PhD student from the Centre for Sustainable Chemical Technologies. “But we hope that in the future we can create clean hydrogen and oxygen fuels from solar energy using perovskite cells.”
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