Category Chemistry/Nanotechnology

Researchers show Transfer of Triplet Exciton Energy from Semiconductor Nanocrystals to Surface-bound Molecular Acceptors

Illustration depicting semiconductor nanocrystal to molecule triplet energy transfer and established subsequent reactions. Credit: Image generated by Dr. Cedric Mongin

Illustration depicting semiconductor nanocrystal to molecule triplet energy transfer and established subsequent reactions. Credit: Image generated by Dr. Cedric Mongin

It extends the lifetime of originally prepared excited state by 6 orders of magnitude. This has implications for solar energy conversion to photochemical synthesis to optoelectronics to light therapy for cancer Rx. Excitons are the electron/hole pairs formed in semiconductor nanocrystals upon absorption of light, temporarily storing it as chemical energy. In solar cells, for example, excitons transport energy through the material so that it can be collected and converted into electricity.

In terms of photochemistry, the major drawback to using most semiconductor nanocrystals as photosensitizers lies in their short excited st...

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Self-Heating Lithium-ion battery could beat the Winter Woes

This image shows an all-climate battery that rapidly self-heats battery materials and electrochemical interfaces in cold environments. Credit: Chao-Yang Wang, Penn State

This image shows an all-climate battery that rapidly self-heats battery materials and electrochemical interfaces in cold environments. Credit: Chao-Yang Wang, Penn State

A Li ion battery that self heats if <32F temp has multiple applications, but may have the most impact on relieving winter ‘range anxiety’ for electric vehicle owners. “It is a long standing problem that batteries do not perform well at subzero temperatures,” said Prof. Chao-Yang Wang. “This may not be an issue for phones and laptops, but is a huge barrier for electric vehicles, drones, outdoor robots and space applications.”

Conventional batteries at below freezing temperatures suffer severe power loss, which leads to slow charging in cold weather, restricted regenerative breaking and reduction of vehicle cruise range by a...

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Alternative to Chlorine: Mechanism for Direct Synthesis of H2O2 on palladium cluster catalysts revealed

Instead of reacting together on the surface of the catalyst (the palladium cluster), the hydrogen atoms dissociate into their components -- protons and electrons. The protons enter the surrounding solution of water and methanol, while the electrons flow through the palladium itself into oxygen molecules. Credit: American Chemical Society

Instead of reacting together on the surface of the catalyst (the palladium cluster), the hydrogen atoms dissociate into their components — protons and electrons. The protons enter the surrounding solution of water and methanol, while the electrons flow through the palladium itself into oxygen molecules. Credit: American Chemical Society

It paves the way to design improved catalysts to produce H2O2 to use in place of harmful chlorine, regardless of the scale of the production facility. From the polyurethane that makes our car seats to the paper made from bleached wood pulp, chlorine can be found in a variety of large-scale manufacturing processes...

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High-Performance material Polyimide for the 1st time with Angular Shape

Salt crystals which can be turned into polyimide. Credit: Image courtesy of Vienna University of Technology, TU Vienna

Salt crystals which can be turned into polyimide. Credit: Image courtesy of Vienna University of Technology, TU Vienna

Using a new synthesis procedure developed at TU Wien, it is now possible to produce the extremely resistant material polyimide in the form of angular particles for the first time. Polyimides withstand extreme heat and chemically aggressive solvents, while being considerably less dense than metals. That is why they are very popular in industry, for example as an insulation layer on PCBs or in aerospace applications. However, it is precisely their high stability, which makes polyimides very difficult to process. Neither melting nor etching can be used to bring them into the correct shape.

“Small plastic particles are usually obtained as spherical objects,” says Miriam Unter...

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