New ‘Solar Paint’ Can Split Water Vapor into Hydrogen and Oxygen with Exposure to Sunlight

Researchers from RMIT University of Melbourne, Australia have developed a kind of solar paint. The unique ink-like substance can absorb water vapor and split it to generate hydrogen, the cleanest source of energy. The paint acts like the hygroscopic packets of silica gel that absorb moisture to keep food, vitamins, medicines, and electronics dry and fresh.

Unlike silica gel, however, the new material, synthetic molybdenum-sulphide, also has properties of a semiconductor. The material’s ability to attract water vapor is so strong that it can provide the only needed source of water for the process.

With energy from exposure to sunlight, the material catalyzes the splitting of water atoms into hydrogen and oxygen. The substance is in the form of ink or paint that can be painted onto an insulating substrate such as glass.

Dr. Torben Daeneke, the lead researcher from RMIT University, said, “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.

“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.”

“Our new development has a big range of advantages,” he said. “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.”

Co-author, distinguished professor Kourosh Kalantar-zadeh, said hydrogen is the cleanest source of energy and can be used in fuel cells. Kalantar-zadeh also said that hydrogen could be used as an alternative to fossil fuels to power conventional combustion engines. “This is an extraordinary concept – making fuel from the sun and water vapor in the air,” said Kalantar-zadeh.

The researchers published their findings in ACS Nano.

Reference

Daeneke, T. et al. Surface Water Dependent Properties of Sulfur-Rich Molybdenum Sulfides: Electrolyteless Gas Phase Water Splitting. ACS Nano, Article ASAP. DOI: 10.1021/acsnano.7b01632.