Nav: Home

Driving chemical reactions with light

May 06, 2019

How can chemical reactions be triggered by light, following the example of photosynthesis in nature? This process is still poorly understood. However, researchers from Johannes Gutenberg University Mainz (JGU) in Germany und Rice University in Houston, USA, have now uncovered a major piece of the puzzle. Their findings have been published recently in Science Advances.

Trees, bushes and other plants are extremely efficient in converting water and carbon dioxide into oxygen and glucose, a type of sugar, by means of photosynthesis. If we can discover the fundamental physical mechanisms involved and harness them for other general applications, the benefits for mankind could be huge. The energy of sunlight, for example, could be used to generate hydrogen from water as a fuel for automobiles. The technique of utilizing light-driven processes like those involved in photosynthesis in chemical reactions is called photocatalysis.

Plasmons: electrons oscillating in synchrony

Scientists commonly use metallic nanoparticles to capture and harness light for chemical processes. Exposing nanoparticles to light in photocatalysis causes so-called plasmons to be formed. These plasmons are collective oscillations of free electrons in the material. "Plasmons act like antennas for visible light," explained Professor Carsten Sönnichsen of Mainz University. However, the physical processes involved in photocatalysis involving such nano-antennas have yet to be grasped in detail. The teams at JGU and Rice University have now managed to shed some light on this enigma. Graduate student Benjamin Förster and his supervisor Carsten Sönnichsen have been investigating this process more extensively.

Modifying plasmon resonances

Förster primarily concentrated on determining how illuminated plasmons reflect light and at what intensity. His technique employed two very particular thiol isomers, molecules whose structures are arranged as a cage of carbon atoms. Within the cage-like structure of the molecules are two boron atoms. By altering the positions of the boron atoms in the two isomers, the researchers were able to vary the dipole moments, in other words, the spatial charge separation over the cages. This led to an interesting discovery: If they applied the two types of cages to the surface of metal nanoparticles and excited plasmons using light, the plasmons reflected different amounts of light depending on which cage was currently on the surface. In short, the chemical nature of the molecules located on the surface of gold nanoparticles influenced the local resonance of the plasmons because the molecules also alter the electronic structure of the gold nanoparticles.

Teamwork crucial for results

Cooperation was essential in the project. "We would never have been able to achieve our results single-handedly," said Sönnichsen. Benjamin Förster spent a year funded by the Graduate School of Excellence Materials Science in Mainz (MAINZ) researching at Rice University in Houston with Professor Stephan Link, who has been visiting professor at MAINZ since 2014. Although the funding of the MAINZ Graduate School provided by the German federal and state governments' Excellence Initiative will be ending in October 2019, Mainz University will - in special cases - continue to provide postgraduates with financial support for this kind of long-term stays abroad. This will be organized under the auspices of the Max Planck Graduate Center (MPGC) and in cooperation with the state of Rhineland-Palatinate.
-end-
Related links:

https://www.mainz.uni-mainz.de/ - Graduate School of Excellence Materials Science in Mainz (MAINZ) ;

https://www.mainz.uni-mainz.de/mainz-visiting-professors/prof-stephan-link/ - MAINZ Visiting Professor Stephan Link ;

http://www.uni-mainz.de/presse/16589_ENG_HTML.php - press release "Chemists develop innovative nano-sensors for multiple proteins" (31 July 2013)

Johannes Gutenberg Universitaet Mainz

Related Photosynthesis Articles:

Scientists design molecular system for artificial photosynthesis
A molecular system for artificial photosynthesis is designed to mimic key functions of the photosynthetic center in green plants -- light absorption, charge separation, and catalysis -- to convert solar energy into chemical energy stored by hydrogen fuel.
Photosynthesis in the dark? Unraveling the mystery of algae evolution
Researchers compared the photosynthetic regulation in glaucophytes with that in cyanobacteria, to elucidate the changes caused by symbiosis in the interaction between photosynthetic electron transfer and other metabolic pathways.
Mechanism behind the electric charges generated by photosynthesis
Photosynthesis requires a mechanism to produce large amounts of chemical energy without losing the oxidative power needed to break down water.
Research shows global photosynthesis on the rise
Researchers found a global historic record by analyzing gases trapped in Antarctic snow to see the rapid rise in photosynthesis over the past 200 years.
Artificial photosynthesis steps into the light
Rice University leads a project to create an efficient, simple-to-manufacture oxygen-evolution catalyst that pairs well with semiconductors for advanced solar cells.
New study shines light on photosynthesis
Researchers have solved a longstanding mystery in photosynthesis, a process used by plants and other organisms to convert light energy into chemical energy.
Study: Viruses support photosynthesis in bacteria -- an evolutionary advantage?
Viruses propagate by infecting a host cell and reproducing inside.
Accelerated chlorophyll reaction in microdroplets to reveal secret of photosynthesis
The research team of DGIST's fellow Hong-Gil Nam, discovered the natural control of chlorophyll activity.
Mechanism for photosynthesis already existed in primeval microbe
A Japanese research team has discovered an evolutionary model for the biological function that creates CO2 from glucose in photosynthesis.
WSU researchers discover unique microbial photosynthesis
Researchers at Washington State University have discovered a new type of cooperative photosynthesis that could be used in engineering microbial communities for waste treatment and bioenergy production.

Related Photosynthesis Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Anthropomorphic
Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#SB2 2019 Science Birthday Minisode: Mary Golda Ross
Our second annual Science Birthday is here, and this year we celebrate the wonderful Mary Golda Ross, born 9 August 1908. She died in 2008 at age 99, but left a lasting mark on the science of rocketry and space exploration as an early woman in engineering, and one of the first Native Americans in engineering. Join Rachelle and Bethany for this very special birthday minisode celebrating Mary and her achievements. Thanks to our Patreons who make this show possible! Read more about Mary G. Ross: Interview with Mary Ross on Lash Publications International, by Laurel Sheppard Meet Mary Golda...