A protective layer applied to gold nanoparticles can strengthen their resilience

For the first time, researchers, including those from the University of Tokyo, have discovered a way to improve the durability of gold catalysts by creating a protective layer of metal oxide clusters. Enhanced gold catalysts can withstand a wider range of physical environments than equivalent unprotected materials.

This advancement could increase the range of possible applications of catalysts, as well as reduce energy consumption and costs in certain situations. These catalysts are widely used in industrial settings, particularly in chemical synthesis and drug production. These industries could benefit from improved gold catalysts.

The search appears in Natural communications.

Everyone loves gold: athletes, pirates, bankers, everyone. Historically, it is an attractive metal from which objects like medals, jewelry, coins, etc. can be made. The reason gold appears so shiny and attractive to us is that it is chemically resistant to physical conditions that might otherwise tarnish other materials: for example, heat, pressure, oxidation, and other damage.

Paradoxically, however, at the nanoscale, tiny gold particles reverse this trend and become very reactive, so much so that they have long been essential for the realization of different types of catalysts, intermediate substances that accelerate or enable one way or another a reaction. chemical reaction to take place. In other words, they are useful or necessary for transforming one substance into another, hence their widespread use in synthesis and manufacturing.

“Gold is a wonderful metal and is rightly praised in society, and especially in science,” said Associate Professor Kosuke Suzuki of the Department of Applied Chemistry at the University of Tokyo. “It’s a great catalyst and can help us synthesize a whole range of things, including drugs.

“The reasons for this are that gold has a low affinity for absorbing molecules and is also very selective in what it binds with, allowing very precise control of chemical synthesis processes. Gold catalysts often operate at lower temperatures and pressures than traditional catalysts, requiring less energy and reducing environmental impact.

As good as gold is, it does have some drawbacks. It becomes more reactive as smaller particles are made of it, and there is a point at which a gold-based catalyst can begin to suffer negatively from heat, pressure, corrosion, oxidation and other conditions. Suzuki and his team believed they could improve this situation and designed a new protective agent that could allow a gold catalyst to retain its useful functions, but under a wider range of physical conditions that typically hinder or destroy a typical gold catalyst.

“The gold nanoparticles currently used in catalysts have some level of protection, thanks to agents such as dodecanethiols and organic polymers. But our new one is based on a group of metal oxides called polyoxometalates and offers results well higher levels, especially with regard to oxidative stress,” Suzuki said.

“We are currently investigating the new structures and applications of polyoxometalates. This time, we applied the polyoxometalates to gold nanoparticles and found that polyoxometalates improve the durability of the nanoparticles. The real challenge was to apply a wide range of analytical techniques to test and verify all of this.”

The team used various techniques known collectively as spectroscopy. He used no fewer than six spectroscopic methods varying in the type of information they reveal about a material and its behavior. But generally speaking, they work by shining some kind of light onto a substance and measuring using specialized sensors how that light changes in one way or another. Suzuki and his team spent months running various tests and different configurations of their experimental hardware until they found what they were looking for.

“We are not just looking to improve certain chemical synthesis methods. There are many applications of our improved gold nanoparticles that could be used to benefit society,” Suzuki said. “Catalysts to reduce pollution (many gasoline cars already have a familiar catalytic converter), less impactful pesticides, green chemistry for renewable energy, medical interventions, sensors for original pathogens food, the list is long.

“But we also want to go further. Our next steps will be to improve the range of physical conditions to which we can make gold nanoparticles more resilient, and also to see how we can add some durability to other useful catalytic metals like ruthenium, rhodium, rhenium, and of course, something people value even more than gold: platinum.”