One way to produce hydrogen gas today is through the process of electrolysis, where an electrical current is applied to water to split it into hydrogen and oxygen. Using clean water as a starting point for this process is appealing – we have even seen desktop hydrogen extraction kits for the home – but what if you could do it without the energy source, and pull harmful particles from the air at the same time?
"One of the main differences with electrolysis, is that in our setup no additional electrical energy is required," the University of Leuven's Sammy Verbruggen explains to New Atlas. "The device runs on contaminated air and light, that's it. The invention began with the discovery by the team members at University of Leuven, who found out that production of hydrogen gas using this device does not necessarily require clean liquid water, but it can also be done by capturing water molecules out of mid-air. Here we take the next step by using polluted air and this seems to work even better."
The device consists of two chambers separated by membrane. On one side, a titanium-dioxide-based photocatalyst is activated by light to break down organic molecules and purify the air. These molecules then migrate through the membrane to the second chamber, Verbruggen explains, where a chemical reaction involving a platinum-based catalyst turns them into hydrogen gas, which can be stored and used as fuel. So, what kind of pollutants are we talking about exactly?
"In fact we target all different kinds of volatile organic compounds," says Verbruggen. "Here we specifically studied the applicability for methanol, ethanol and acetic acid, but the field of application will certainly not be limited to those three compounds."
Verbruggen notes that actual storage of hydrogen is not a function of this device, and it in itself is an entire field of research. In any case, the actual power yield at this stage of development is quite low. He also points out, however, that it requires no external power source and therefore every molecule of hydrogen gas produced can be considered a net gain. And that's not to mention the benefits of removing of pollutants from the air.
In its current form, the team is working on a scale of a few square centimeters. It says the processes underlying the technology resemble those found in solar panels, and for this reason it plans to optimize the materials to use sunlight to activate the device.
"We are now working to improve the cell's performance toward industrial relevance," says Verbruggen. "For instance, one of the key aspects we are looking at is to improve the light-efficiency of the catalyst that drives the gas-purification reactions. We want to be able to effectively use a larger fraction of incoming solar light."
The research was published in the journal ChemSusChem.
May 10, 2017 Source: University of Leuven