HomeNewsNanotechnologyTuning chemical reactions with gentle

Tuning chemical reactions with gentle

Oct 04, 2021

(Nanowerk News) The chemical business consumes numerous power, not solely to provoke reactions but in addition to separate merchandise from by-products. In a promising rising discipline of analysis, scientists worldwide try to make use of nanoscale antennas to seize and focus gentle into tiny volumes with a purpose to provoke chemical reactions extra effectively and sustainably. Researchers at AMOLF unraveled how such nanoscale antennas improve the speed of chemical reactions. They additionally found that utilizing totally different colours of sunshine could cause utterly totally different chemical reactions to happen. “This research is still very fundamental, but it shows that it could be possible to design a sunlight powered chemical reactor with these nano-antennas and in which different reactions – and thus different end products – can be chosen. This has potentially huge economic and environmental implications,” says Eitan Oksenberg, a postdoc within the Nanoscale Solar Cells group led by Erik Garnett at AMOLF. They printed these findings in Nature Nanotechnology (“Energy-resolved plasmonic chemistry in individual nanoreactors”). At the interface of chemistry and optics, a brand new analysis discipline has just lately emerged that investigates the method of so-called plasmonic photocatalysis. In this course of, the distinctive skill of metallic nanostructures to pay attention gentle into sub-nanoscale volumes is used to provoke chemical reactions. “This research is still fundamental, but the concept is very attractive. One reason for that is: many industrial chemical reactions are already catalyzed at the surface of metals”, says Oksenberg. “The idea is that if you concentrate ambient light into very small volumes, you get reaction hot spots in which high temperature or pressure are not needed for an efficient chemical reaction to take place.”

Resolving ambiguities

However thrilling it could be, progress within the discipline is hindered by the anomaly across the actual mechanism that drives the chemical response. Oksenberg: “When nanoscale metal particles are exposed to the right color of light, they act as antennas that capture and concentrate light into a very small volume, which can drive a chemical reaction. Scientists are still debating whether such reactions are driven directly by the concentrated light, by the high energy electrons formed in the metal, or by heat that builds up in the metal when the electrons dissipate their energy.”

Tuning chemical reactions

Oksenberg and his colleagues developed a approach to experimentally discriminate between the totally different doable driving mechanisms. “It is not straightforward to probe what is going on at the surface of metal nanoparticles because the antenna shows a much stronger interaction with light than the molecules that undergo the chemical reaction”, he explains. “However, when the molecules change at the surface of the metal nanoparticle, they cause small changes to the antenna, such as its color and bandwidth. By measuring the reflection of light of more than a thousand individual metal nanoparticles, we can closely monitor these changes over time to get a glimpse into the kinetics of the chemical reaction.” Oksenberg and his colleagues used a configuration of gold nanocubes on a mirror, the place a small hole between dice and mirror varieties a nano-antenna that concentrates gentle with a particular shade. A molecule referred to as Methylene-blue is sure to the gold particles. Small variations within the measurement of each the cubes and the hole end in variations within the antenna shade, which has dramatic implications for the chemical response that takes place: whereas brilliant pink gentle (1.9 eV) cuts off a portion of the molecule, utilizing a barely darker shade of pink (1.7 eV) forces the whole molecule to go away the floor of the metallic particle. (click on on picture to enlarge) The researchers anticipated to have the ability to uncover how precisely chemical reactions are enhanced by metallic nano-antennas, however they discovered that there are a number of methods. “Even in our very simple chemical system, we saw that different driving mechanisms occur at different colors of light, leading to distinct chemical reactions. This means it is possible to tune the chemical reaction products by choosing the color of the light.”

Selective chemistry

This discovery may be very promising for future functions utilizing metallic nanoparticle antennas in chemistry. Oksenberg: “As a scientist, I am excited by the ability to tune a chemical reaction with light and by the richness of the chemistry that we are just beginning to uncover. If we can expand our research to other colors of light outside the visible spectrum, we might even find entirely new chemical pathways that can be triggered with plasmonic resonances. This has the potential to become a disruptive technology. A chemical reactor based on the principles we discovered, is not only very fast and very specific, but also requires very straightforward conditions, like ambient temperature while needing only sunlight as its energy source. The possibility to make the chemical industry more efficient and sustainable with this concept, has huge economic and environmental implications.”

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