Ultrafast laser experiments pave way to better industrial catalysts

November 9, 2020

Arizona State University's Scott Sayres and his team have recently published an ultrafast laser study on uncharged iron oxide clusters, which could ultimately lead to the development of new and less-expensive industrial catalysts. It might also contribute to a better understanding of the universe since iron oxides are observed in the emission spectra of stars.

Sayres is an assistant professor in ASU’s School of Molecular Sciences and a faculty member in the Biodesign Institute’s Center for Applied Structural Discovery. Scott Sayres Scott Sayres is an assistant professor in ASU’s School of Molecular Sciences and a faculty member in the Biodesign Institute’s Center for Applied Structural Discovery. Download Full Image

Most chemical industries utilize catalysts to enhance the rate of reaction and selectivity in obtaining their desired products. For example, catalytic converters in the exhausts of our vehicles commonly use platinum, palladium and rhodium to help break down pollutants.

All three of these metals are significantly more expensive than gold, which is in turn a lot more costly than iron. On average a catalytic converter costs $1,000 but can be as high as $3,000 per vehicle.

“Transition metal oxides are widely used as heterogeneous catalysts in the chemical industry,” Sayres said. “The photocatalytic process proceeds through a series of complex reactions, and a fundamental understanding of these catalytic mechanisms is still lacking. Gas-phase studies on molecular scale clusters allow us to probe chemical activities and mechanisms in an unperturbed environment. The atomic precision of clusters can be utilized to identify preferred adsorption sites, geometries or oxidation sites that enable chemical transformations.”

The FenOm clusters under investigation here have different compositions: n and m vary but are less than 16. Fe is the chemical symbol for iron and O refers to oxygen.

Jake Garcia

“This research has not only revealed the stable fragments of bulk iron oxide materials but has shown how the change in atomic composition may affect stability and reactivity of these fragments,” said Jake Garcia, graduate student and first author of this paper.

“By resolving the excited state dynamics of atomically precise materials such as iron oxides, we move one step closer to creating more directed molecular catalysts and understanding the reactions which may take place in interstellar media.”

Garcia continues that he has found a passion for building experimental instruments in Sayres’ lab, and loves studying materials relevant to planetary and earth science.

Ryan Shaffer, who was an undergraduate student working in Sayres’ lab, is the second author of the current work.

Detecting iron oxide clusters

Experiments with electrically charged clusters have been common because they can be mass selected with electric or magnetic forces and subsequently reacted individually. Cluster ions are clearly much more reactive than their condensed-phase analogues and neutrals because of their net charge. 

Far less work has been done with neutral clusters reported here, which are even better mimics of the true active sites of condensed phases and their surface chemistry. The net charge significantly affects cluster reactivity, and the influence becomes more important as the cluster size decreases due to charge localization. 

“The timeframe of electron transitions following excitation is of fundamental interest to the understanding of reaction dynamics. Clusters are atomically precise collections of atoms, where the addition or subtraction of a single atom may drastically change the reactivity of the cluster,” Sayres said. “In this work we apply ultrafast pump-probe spectroscopy to study the speed at which energy moves through small iron oxide clusters.”

The laser pulses are extremely short: one thousandth of a billionth of a second.

research works in lab

Jake Garcia works in the lab.

Sayres concludes that the excited state lifetime is strongly affected by atomically precise changes to the cluster composition. Specifically, the higher the oxidation states of the metal, the faster the photoexcitation energy is converted into vibrations. They have found that the excited state lifetimes rely heavily on size and oxidation state.

Catalysts are also extensively used to minimize the harmful byproduct pollutants in environmental applications. Enhanced reaction rates translate to higher production volumes at lower temperatures with smaller reactors and simpler materials of construction.

When a highly selective catalyst is used, large volumes of desired products are produced with virtually no undesirable byproducts. Gasoline, diesel, home heating oil and aviation fuels owe their performance quality to catalytic processing used to upgrade crude oil.

Intermediate chemicals in the production of pharmaceutical products utilize catalysts, as does the food industry in the production of every day edible products. Catalysts are playing a key role in developing new sources of energy and a variety of approaches in mitigating climate change and controlling atmospheric carbon dioxide.

Jenny Green

Clinical associate professor, School of Molecular Sciences


ASU Law students engage in dialogue with inventor of the Super Soaker

Lonnie Johnson speaks with patent law students about his path from engineering spacecraft to creating the No. 1 best-selling water toy ever

November 9, 2020

An American treasure. Revolutionary inventor. Spacecraft engineer. Holder of more than 140 patents. Creator of the No. 1 top-selling water toy of all time – the  Super Soaker.

As Professor Jon Kappes of the Sandra Day O’Connor College of Law at Arizona State University said to his patent law class students: “I hope after hearing from Dr. (Lonnie) Johnson today, when you close your eyes and picture the word ‘inventor,’ you’ll think of Dr. Johnson.” Photo of Lonnie Johnson Lonnie Johnson, a former Air Force and NASA engineer who invented the Super Soaker, shared his journey of invention recently with ASU Law's patent law class students. Download Full Image

Kappes, ASU Law intellectual property law lecturer and Center for Law, Science and Innovation faculty fellow, hosted Johnson on Oct. 21 in a compelling dialogue with ASU Law students. The former Air Force and NASA engineer discussed how he came up with the idea for the Super Soaker and how much continuing to invent, loving what you do and being persistent make all the difference in creating a lasting career.

“Invention is like producing a hit record — you never know what’s going to be a major success — and the Super Soaker was (my) hit in that regard,” Johnson said in the interactive Zoom discussion. “It’s very subjective. And it’s just a matter of timing what people like and what they’re ready for at that point in time.”

And that means you have to be persistent in your work, added Johnson, CEO and founder at Johnson Research & Development and CEO of Johnson Battery Technology.

“It's been quite a journey from my days as a small child as an inventor and working on a robot, to high school back in the ’60s, to working on outer-planetary spacecraft,” Johnson said. “I have an invention on the Galileo spacecraft that went to Jupiter.”

In fact, it was during Johnson’s time working on Galileo in the Jet Propulsion Laboratory that he came up with the idea for the Super Soaker.

“I was at home and experimenting on my own ideas, and I was working on this heat pump that would use water as a working fluid and I hooked it up to a nozzle-like machine to my bathroom sink,” Johnson said. “The stream of water coming out of the nozzle was so impressive. I turned and shot the stream into the bathtub, and I thought to have a high-performance, high-pressure water gun would really be satisfying.”

So Johnson put the heat pump project aside and started building the water gun, leveraging his mechanics and engineering training.

“I got the idea in 1982 and it didn’t make it to market until ’91 and then became the No. 1 best-selling water toy – only about 10 years in the making. So I always say the key to success is perseverance,” he said, adding that inventing is about finding a good problem to solve. “Every ambitious project has useful results.”

Kappes, who mentioned his Super Soaker 200 was one of his favorite childhood toys, said Johnson’s story is a message for students to start developing their own ideas. “Now’s the time – you can begin inventing now. I don’t know many patent attorneys who don’t have their own patents.”

To inspire the next generation of engineers, Johnson’s nonprofit, the Johnson STEM Activity Center, is funding high school robotics teams and offering them a creative work space in the greater Atlanta region. He said the center reaches about 10,000 kids a year, and has a smaller number of kids who actually build robots at the center and compete on several teams in the first robotics program.

“It’s extremely inspiring for me to see these kids experience success building robots and doing things that they had not anticipated they'd be able to do,” Johnson said. “And the real benefit from that is that once they are successful, they internalize that — and that’s not something you can take away from a person. Realizing that they're able to do, and capable of doing, things beyond what they have been told up to that point is life-changing.”

Learn more about the Johnson STEM Activity Center. Hear more from Johnson’s dialogue with Kappes and ASU Law students in the video below: 

Video by ASU Law

Julie Tenney

Director of Communications, Sandra Day O'Connor College of Law