Solar paint turns air moisture into hydrogen fuel
Hydrogen itself is seen as a key part of our clean-energy future, but even better would be hydrogen produced using the power of the sun, rather than electricity from the grid. And what if you could make your house look pretty at the same time? Researchers in Australia have made a promising breakthrough on all counts, developing a "solar paint" that can produce hydrogen wherever there happens to be moisture in the air.
Hydrogen gas has great potential as a source of sustainable fuel, because it burns clean and produces only water as a by-product. It holds huge promise for use in fuel cells in addition to other areas if we can work out a way to store it safely. But another of the key challenges when it comes to hydrogen is its production – currently most of it comes from fossil fuels.
Hydrogen is often produced by using electricity to split water molecules into hydrogen and oxygen. So where that electricity comes from has the final say in whether it can be truly defined as a renewable fuel source. This has inspired numerous research efforts to derive the gas from solar power, with one recent example even capturing polluted air at the same time.
Now researchers at Australia's RMIT University have developed what they describe as a solar paint that can generate hydrogen. The key is a newly developed compound similar to the silica gel you'll find in those packets that keep burritos and shoes dry by absorbing moisture.
Called synthetic molybdenum-sulphide, this compound has one key advantage over silica gel, however, in that it also acts as a semi-conductor, triggering the splitting of water atoms into hydrogen and oxygen. The team then found that mixing this compound with titanium oxide particles could form part of a sun-absorbing, hydrogen-generating paint.
"Titanium oxide is the white pigment that is already commonly used in wall paint, meaning that the simple addition of the new material can convert a brick wall into energy-harvesting and fuel-production real estate," says lead researcher Dr Torben Daeneke. "Our new development has a big range of advantages. There's no need for clean or filtered water to feed the system. Any place that has water vapor in the air, even remote areas far from water, can produce fuel."
The team's research doesn't address ways of storing the hydrogen, which is very difficult owing to the incredibly small and light molecules that make up the gas. Indeed hydrogen storage itself makes up an entire field of research, a lot of which focuses on creating compact storage systems for cars, though progress is being made towards advanced materials for a hydrogen-carrying pipeline infrastructure, too. When and if these solutions do come along, perhaps they'll be drawing on your fresh coat of house paint to get their fill.
The research was published in the journal ACS Nano, while the video below provides an overview of the breakthrough.