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Improving hydrogen peroxide production through sustainable photocatalysis

Improving hydrogen peroxide production through sustainable photocatalysis

Researchers at Shanghai Jiao Tong University have found ways to make the hot electrons last longer so that photocatalysis can be used to produce hydrogen peroxide in a safer, cleaner manufacturing process. Credit: Nanotechnology, Tsinghua University Press

Hydrogen peroxide is used in many industries for a variety of purposes, including bleaching, sewage treatment, sterilization, and even as a rocket fuel. Because the hydrogen peroxide byproduct is water, it’s hailed as a “green,” eco-friendly chemical, but a closer look at the hydrogen peroxide manufacturing process reveals a more complicated story. Problems such as the amount of energy used for the production process and the extraction of the necessary chemicals have dramatic consequences for the environment. As the demand for hydrogen peroxide increases worldwide, researchers are trying to find new ways to produce hydrogen peroxide that are safer and better for the environment.

Previous research has identified techniques that use photocatalysis, the use of light to initiate a chemical reaction, and hot electrons, high-energy electrons charged by visible and infrared light, as alternative solutions for hydrogen peroxide production. Both photocatalysis and hot electrons have historically been used in green energy alternatives, such as solar energy, but limitations of both processes have prevented them from being implemented for hydrogen peroxide production.

To address some of these limitations, researchers at Shanghai Jiao Tong University have found ways to make the hot electrons last longer so that photocatalysis can be used to produce hydrogen peroxide in a safer, cleaner manufacturing process.

The findings were published on June 25 in Nano-research

Paper author Xinhao Li, a professor in the School of Chemistry and Chemical Engineering at Shanghai Jiao Tong University, explained some limitations of using hot electrons in hydrogen peroxide production. “The lifetime of hot electrons, typically on a time scale of 0.4 to 0.3 picosecond, could not be compared well with the time scale of typical chemical reactions, including the oxygen reduction reaction to hydrogen peroxide. Therefore, it is attractive to develop powerful methods to extend the life of thermized hot supports over inexpensive photocatalysts for hydrogen peroxide production using only water, air and sunlight,” said Li.

The method proposed by researchers to conserve the energy of the hot electrons is simple. A heterojunction – a combination of two different layers of semiconductors – of rutile titanium dioxide and graphene is made to harvest the hot electrons. The first researchers investigated ways to synthetically produce rutile titanium dioxide quickly and efficiently. It takes 24 hours for the phase transfer process to convert anatase titanium dioxide to rutile titanium dioxide using the grinding method, but researchers have reduced this to 5 minutes.

The combination of rutile titanium dioxide and graphene forms a raised Schottky barrier, which is essential for extending the life of hot electrons. A Schottky barrier forms between a metal and a semiconductor and acts as a barrier to electrons. Since the Schottky barrier between rutile titanium dioxide and graphene is high, it facilitates the injection of hot electrons and prevents the electrons from flowing back through the barrier. The increased barrier is achieved due to the rapid phase transfer between anatase titanium dioxide and rutile titanium dioxide. The fast phase transfer and increased barrier provide long fluorescence lifetime and better efficiency, boosting hydrogen peroxide production with visible and near infrared light. Researchers suspect that the graphene/rutile titanium dioxide can be reused for at least six cycles of standard reactions, making it even more efficient at producing hydrogen peroxide.

Looking ahead, researchers are looking ahead at how to simplify the process. “In follow-up work, we hope to develop simpler strategies to optimize the heterostructure of photocatalysis to further improve the utilization of photogenerated hot electrons. This photocatalytic system powered by photogenerated hot electrons at inexpensive noble metal-free heterojunctions shows significant potential as a new artificial photosynthesis system” said Li.

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More information:
Weiyao Hu et al, Rapid and mild transfer of anatase phase from graphene-activated TiO to rutile with increased Schottky barrier: facilitating interfacial hot electron injection for Vis-NIR-driven photocatalysis, Nano-research (2022). DOI: 10.1007/s12274-022-4624-8

Provided by Tsinghua University Press

Quote: Improving Hydrogen Peroxide Production by Sustainable Photocatalysis (2022, June 28) retrieved June 28, 2022 from https://phys.org/news/2022-06-hydrogen-peroxide-production-sustainable-photocatalysis.html

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