Recycling is one of the important solutions for human beings to solve the global plastic waste problem. Among them, most of the plastic waste will still be made into plastic products after being recycled. However, scientists have also been exploring different ways to turn it into more valuable products.

Recently, a team of researchers at Tokyo Metropolitan University has made a new breakthrough in this regard. They found that gold nanoparticles supported on the surface of zirconia can turn waste materials such as biomass and polyester into organosilane compounds, valuable chemicals that can be used in a variety of applications.

The latest research results have been recently published in the "Journal of the American Chemical Society" (JACS). It is claimed to be a greener and less demanding way of upcycling waste, exploiting the "cooperation" between the amphoteric (acid and base) properties of gold nanoparticles and zirconia supports.

In fact, the team has been working on converting plastics and biomass into organosilanes, which are organic molecules that have silicon atoms attached to them, forming carbon-silicon bonds. Specifically, organosilanes are valuable materials for high-performance coatings and intermediates in the production of pharmaceuticals and agrochemicals.

However, the addition of silicon atoms often involves reagents that are sensitive to air and moisture and requires high temperatures, not to mention harsh acidic or basic conditions that may make the conversion process itself an environmental burden. But now, the team has broken through this bottleneck.

It is reported that they applied a hybrid catalyst material consisting of gold nanoparticles supported on a zirconia support. The catalyst employs ether and ester groups, which are abundant in plastics such as polyesters and biomass compounds such as cellulose, to help them interact with a silicon-containing compound called a disilane. Compounds react. Then with just a little heat, they succeeded in creating organosilane groups where the ester or ether groups would have been.

Through a detailed study of the mechanism, the team discovered that the cooperation between the gold nanoparticles and the amphoteric (basic and acidic) properties of the support is responsible for the efficient and high-yield conversion of the starting materials under mild conditions.

Given that plastic waste disposal typically requires combustion or harsh acidic/alkaline conditions, the process itself already offers an easy route to breaking down polyesters under much less demanding conditions. Moreover, the products of the reaction are themselves valuable compounds that can be used in new applications. The team hopes that the new process will form part of humanity's pathway to a carbon-neutral future.

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