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Researchers use fluorine-doping method to construct catalysts with enhanced performance

Onderzoekers gebruiken de fluordopingmethode om katalysatoren te construeren met verbeterde prestaties3+ active sites by electron – withdrawing F doping. Credit: Nano-research” width=”780″ height=”530″/>

The F-doped Fe-NC single-site catalyst retains the advantage of a low overpotential for Fe-NC, with greatly increased CO faraday efficiency and partial current density due to the stabilized Fe3+ active sites by electron-withdrawing F-doping. Credit: Nano-research

As industry has evolved over the past century, excessive carbon dioxide emissions have led to climate problems and global warming. Scientists are constantly working on solutions to the problems of greenhouse gases, which are heating the Earth’s surface and lower parts of the atmosphere. Carbon dioxide is the most abundant of the greenhouse gases.

Carbon dioxide can be electrochemically reduced to valuable chemicals using wind or sunlight derived electrical energies. This electroreduction of carbon dioxide offers scientists a promising strategy for managing the carbon balance on a global scale. Electrochemical reduction of carbon dioxide offers the future potential for converting carbon dioxide into useful, more environmentally friendly chemicals, such as carbon monoxide, methane or ethanol. To achieve carbon dioxide electroreduction, scientists need efficient electrocatalysts. Electrocatalysts are the catalysts used in electrochemical reactions. They can increase the rate of the reaction that occurs. A research team from Nanjing University has constructed catalysts using a fluorine doping method that improves their performance.

The research team reported their findings in Nano-research

Scientists know that cheap metal-nitrogen-carbon single-site catalysts work well for the electroreduction of carbon dioxide to carbon monoxide. Of these, the nickel-nitrogen doped carbon single-site catalysts have the high faraday efficiency of carbon monoxide and a large partial flow. Faraday efficiency describes how efficiently charge is transferred in an electrochemical reaction.

The research team has already increased the faraday efficiency and high partial flow of nickel-nitrogen doped carbon single-site catalysts by doping them. Compared to the nickel-nitrogen doped carbon single-site catalysts, iron-nitrogen-carbon single-site catalysts have lower overpotential for the electroreduction of carbon dioxide. Overpotential describes the voltage efficiency of a cell. Previous research has used fine structure spectroscopy with X-ray absorption to verify that the active sites of the iron-nitrogen-carbon single-site catalysts are Fe.3+ place. this Fe3+ places make the catalyst more effective in carbon dioxide adsorption and carbon monoxide desorption.

The team constructed a fluorine-doped iron-nitrogen-carbon single-site catalyst containing more Fe. possess3+ sites, as they expected. The fluorine-doped iron-nitrogen-carbon single-site catalyst they built retained the advantage of low overpotential. It also promoted the faraday efficiency of carbon monoxide from a volcano-like high value to a high plateau value. “The results indicate the superior stability of fluorine-doped iron-nitrogen-carbon over iron-nitrogen-carbon because of the fluorine doping,” said Lijun Yang, an associate professor of the School of Chemistry and Chemical Engineering, Nanjing University .

The research team concludes that the electron-withdrawing fluorine doping causes the iron-nitrogen-carbon single-site catalyst to retain the advantage of a low overpotential, with much increased carbon monoxide faradaic efficiency and partial current density due to the stabilized Fe3+ place.

The team synthesized the iron-nitrogen-carbon using a heat method called adsorption pyrolysis. They performed the carbon dioxide electroreduction experiments in an H-type cell and a gas diffusion electrode cell. They used theoretical calculations to better understand the improvements that have occurred with the fluorine doping.

“Electrochemical tests demonstrate the enriched defects by fluorine-doping kinetically increasing the electroactive surface area and enhancing charge transfer,” Yang said. Looking forward to further research, the research team’s findings provide them with a simple and verifiable strategy to improve the carbon dioxide electroreduction to carbon monoxide performance of iron-nitrogen-carbon catalysts by stabilizing the Fe.3+ place.


Tandem catalyst to improve the electroreduction of carbon dioxide to methane


More information:
Yiqun Chen et al, Increasing the faraday efficiency of CO2 electroreduction to CO for Fe−N−C single-site catalysts by stabilizing Fe3+ sites via F-doping, Nano-research (2022). DOI: 10.1007/s12274-022-4441-0

Provided by Tsinghua University Press

Quote: Researchers use fluorine doping method to build catalysts with improved performance (2022, June 17) Retrieved June 18, 2022 from https://phys.org/news/2022-06-fluorine-doping-method-catalysts.html

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