​Valentin Rodionov, KAUST assistant professor of chemical science, attended the 252nd American Chemical Society Meeting & Exposition in Philadelphia, Pennsylvania, from August 21 to 24 with Tianyou Chen, a postdoctoral fellow in his research group.

"Tianyou had some very exciting results to present at the conference. He presented research from a project he spent a good part of two years working on because not everything was working out, and proper science never works out right away—it takes time, but it finally worked out. Tianyou's project focuses on something we call 'molecular Scotch tape,' and Tianyou was the driving force behind it, so he was the perfect person to present it at the ACS," Rodionov said.

Working on catalysis

Rodionov and his team examine catalysts, including some of the more useful catalysts in modern chemistry, which are made of nanoparticles.

"The beauty of using these particles for catalysis is that the surface area is huge and they have a lot of surface defects. However, the smaller these particles are, the less stable they are," explained Rodionov.

"The smaller particles want to coalesce into a bigger piece of something, which presents a problem, as at that point they are no longer an able catalyst," he continued. "Chemists have devised a number of techniques over the years to prevent the particles from aggregating. For example, a common way to do this would be to put them on a solid support, like a piece of silica gel. In this case, on the surface they would not really interact with each other much and the aggregation would be inhibited. However, this is not optimal because they tend to fall off. There are other ways of stabilizing them; for example, you can put on other molecules that bind tightly to the surface, but that also kills the catalyst."

Molecular sticky tape

The research team tackled the catalyst problem through inspiration they got from humble Scotch sticky tape.

"What we have devised is a way to make a solid support that is sticky," Rodionov said. "The nanoparticles stick to one side, leaving the other side free to catalyze, and that is why we call our approach 'molecular Scotch tape.' The trick was really to work out the precise composition of whatever we put on the solid support. In this case, we used very cheap and sustainable silica gel. It's a traditional support that we coat with a single molecule layer of soft material. The material has groups in it that bind tightly to gold. Atoms of sulfur combine with the gold to make a very strong chemical bond, so when the gold nanoparticles 'see' the surface, they 'see' the sulfur and attach to it, but there isn't enough sulfur there to kill the catalyst."

Reusing catalysts

The inventive research group has created a more practical nanoparticle aggregation system that was previously underdeveloped in the sphere of chemistry research, but there is another advantage to their system—the catalyst can be reused.

"Traditional techniques for this reaction created a lot of bi-products we didn't want, but with our catalyst, we were able to carry out the reaction under conditions that are more practical than pretty anything else that was reported up until this point. This was really because of our approach, because gold is a great catalyst for this reaction, but it's not stable in its own right and it doesn't recycle well, so normally we cannot reuse the catalyst. However, in combination with our new Scotch sticky tape support, we can actually do that," Rodionov noted.

'Blue skies' research

Like so many researchers and students at KAUST, both Rodionov and his student Chen were drawn to the University because of the unsurpassed research equipment and materials available to them to pursue their research goals.

"KAUST is a very interesting place to be because here we have the opportunity to do 'blue skies research,' or research that would be complicated in other places," Rodionov said. "At KAUST, we can pretty much do whatever we believe in, whatever we are passionate about, and we know we have the resources to actually enable us to do this work."

Chen came to KAUST from Zhejiang University, Hangzhou, China. He pointed out, "I came here for the science and to work with someone like Professor Rodionov. I would not have had the opportunity to conduct this project anywhere else. I've thoroughly enjoyed the opportunities KAUST has given me to meet people from different backgrounds and to work with so many talented chemists on my research projects."

When asked where he imagines their field of research going in the future, Rodionov replied, "We think that it is such a general concept in heterogeneous catalysis, we hope to extend it to other reactions and to other kind of particles—we think that other people will pick it up. At the end of the day, this is something I feel will continue to grow."

- By David Murphy, KAUST News