Researchers from the Royal Melbourne Institute of Technology (RMIT) have developed a “solar paint” which absorbs ambient water vapors and then draws on the Sun’s energy to split it and generate hydrogen — which can be used to create clean power cells.

Power overwhelming!
Image credits David Mark.

Australia has put yet another arrow in the quiver of solar energy. RMIT researchers have developed a compound which can draw moisture from the surrounding air, like a more powerful variety of those tiny silica gel packets that come in new shoes and other products to keep them dry. By itself, that’s not very impressive.

But unlike simple silica, this material, synthetic molybdenum-sulphide, is also a semiconductor and can act as a catalyst to split water molecules into oxygen and hydrogen atoms. This type of reactions hold the key to viable hydrogen economies, which basically use energy to split water molecules, then release that energy cleanly by chemically combining hydrogen back with oxygen. And synthetic molybdenum-sulphides could take care of that first part simply by basking in the sun.

“We found that mixing the compound with titanium oxide particles leads to a sunlight-absorbing paint that produces hydrogen fuel from solar energy and moist air,” says lead researcher Dr Torben Daeneke, from RMIT University in Melbourne, Australia.

“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.

The paint has some very compelling arguments over current water-splitting technologies. Since it draws on water vapor, there’s no need for a filtering or pump system to supply it with impurity-free water. It can also produce fuel anywhere that has sunlight and water to evaporate. That means remote areas with plenty of sunlight and sufficient water, as well as the coasts of deserts and other very hot climate types can be put to work producing power. And the only byproduct of this process is good old oxygen! Smells like a good deal.

Ok, that’s pretty cool and all but why not use regular solar panels? Why go through the hassle of implementing a whole new tech when we can already harness sunlight as energy? Well, regular solar panels produce electrical energy but RMIT’s paint produces a hydrogen fuel. You can bottle it, for starters, something physics isn’t big on with ‘pure’ energy — you have to transform it into other types of energy and waste some in the process.

Fuel doesn’t have that issue. Pump it into tanks and it can be shuttled anywhere and anytime it’s needed since you can just build up a stock of the stuff. And it can be used to power fuel cells as well as conventional combustion engines — with the added benefit that they’d spit out water instead of exhaust. For communities that can’t afford to shift to electric engines, hydrogen fuel is a really attractive way of keeping current vehicles and infrastructure in use while virtually deleting their emissions. That means better health, better environmental footprint, all with comparatively minimal investment.

The only catch is that for now, producing hydrogen fuel remains a very energy-intensive and cost-prohibitive endeavor — something which technology such as this will hopefully soon change.

The full paper “Surface Water Dependent Properties of Sulfur-Rich Molybdenum Sulfides: Electrolyteless Gas Phase Water Splitting” has been published in the journal ACS Nano.