Scheme of the local surface chemistry modification and AuNPs tracking approach. (a) Ag nanoantennas were modified overnight with 1 mM ethanolic solution of 4-NTP. Several ethanol/water washing steps were performed on each sample. (b) 4-NTP-coated antennas were immersed in 0.1 M HCl solution and illuminated for different times at their LSPR wavelength (633 nm) with a power density of 1 W cm−2. Samples were rinsed with water and immediately dipped in the activated AuNP suspension. (c) AuNPs (15 nm) coated with 11-mercaptoundecanoic acid (MUA) as a capping layer were suspended in HEPES buffer and mixed with 1 mM EDC and 1 mM NHS, and left to react for 30 min followed by two purification centrifugation steps. (d) The activated and purified AuNPs were left in contact with the hot-electron-converted Ag antennas to react overnight, thus creating the amide (–NH–C=O) bond. Several washing steps with HEPES buffer and water were performed before 2 nm of Pt were sputtered for SEM imaging.
Artificial photosynthesis could soon become much more efficient thanks to nanomaterials. This is the conclusion of a study published today led by researchers in the Department of Physics at Imperial College London, which could ultimately help improve solar energy technologies and be used for new applications, such as using sunlight to break down harmful chemicals.
The efficiency of this reaction is very high but so far scientists have been unable to mimic this process in humanmade artificial devices. One reason is that many molecules that can undergo chemical reactions with light do not efficiently absorb the light themselves. They rely on photocatalysts – materials that absorb light efficiently and then pass the energy on to the molecules to drive reactions. In the new study, researchers have investigated an artificial photocatalyst material using nanoparticles and found out how to make it more efficient.
This could lead to better solar panels, as the energy from the Sun could be more efficiently harvested. The photocatalyst could also be used to destroy liquid or gas pollutants, such as pesticides in water, by harnessing sunlight to drive reactions that break down the chemicals into less harmful forms.
Dr Emiliano Cortés from the Department of Physics at Imperial, said: “This finding opens new opportunities for increasing the efficiency of using and storing sunlight in various technologies. “By using these materials we can revolutionize our current capabilities for storing and using sunlight with important implications in energy conversion, as well as new uses such as destroying pollutant molecules or gases and water cleaning, among others.”
The material is made of metal nanoparticles and the researchers showed that light-induced chemical reactions occur in certain regions over the surface of these nanomaterials. They identified which areas of the nanomaterial would be most suitable for transferring energy to chemical reactions, by tracking the locations of very small gold nanoparticles (used as a markers) on the surface of the silver nanocatalytic material.
Now that they know which regions are responsible for the process of harvesting light and transferring it to chemical reactions, the team hope to be able to engineer the nanomaterial to increase these areas and make it more efficient. Professor Stefan Maier said: “This is a powerful demonstration of how metallic nanostructures, which we have investigated in my group at Imperial for the last ten years, continue to surprise us in their abilities to control light on the nanoscale.
“The new finding uncovered by Dr Cortés and his collaborators in Germany and the US opens up new possibilities for this field in the areas photocatalysis and nanochemistry.” http://www3.imperial.ac.uk/newsandeventspggrp/imperialcollege/newssummary/news_28-3-2017-11-24-35 http://www.nature.com/articles/ncomms14880
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