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The MIT team’s research focussed on a class of oxides called perovskites
31/07/2015
Close link between wetting and catalysis
MIT finds new relationship
Richard Jansen-Parkes
RESEARCHERS at the US’ MIT have found that there is a much closer link between catalysis and wetting than previously thought.
These two key physical phenomena both take place at the surfaces of materials. A catalyst enhances the rate of chemical reactions, while wetting determines how liquids spread across a surface. Knowledge on a link between them could make it easier to find new catalysts for particular applications, among other potential benefits.
“What’s really exciting is that we’ve been able to connect atomic-level interactions of water and oxides on the surface to macroscopic measurements of wetting, whether a surface is hydrophobic or hydrophilic, and connect that directly with catalytic properties,” says Yang Shao-Horn, a professor at MIT and one of the leaders of the research.
The MIT team’s research focussed on a class of oxides called perovskites, which it says are of interest for applications such as gas sensing, water purification, batteries and fuel cells.
The new understanding was made possible by an experimental technique, explains Kelsey Stoerzinger, a graduate student at MIT and the research’s lead author. While most attempts to study surface science use instruments that require a vacuum, the MIT team used one that would work in humid air, at room temperature, and with varying degrees of water vapour present. Experiments using this system, called ambient pressure X-ray photoelectron spectroscopy, revealed that the reactivity with water is key to the whole process.
Since determining a surface’s wettability is “trivially easy” according to Kripa Varanasi, an associate professor of mechanical engineering, that determination can now be used to predict a material’s suitability as a catalyst. And as researchers looking at these kinds of interactions tend to specialise in either wettability or catalysis, this produces a framework for people in both fields to work together to advance our knowledge.
“We show how wetting and catalysis, which are both surface phenomena, are related and how electronic structure forms a link between both,” says Varanasi.
“This is a step forward, providing a molecular-level understanding,” adds Shao-Horn.
The Journal of Physical Chemistry DOI: 10.1021/acs.jpcc.5b06621
