As the industry has evolved over the last century, excess carbon emissions have led to climate problems and greenhouse effects. Scientists are constantly working to solve the problems of greenhouse gases that warm the earth’s surface and lower atmosphere. Carbon dioxide is the most abundant of greenhouse gases.
Carbon dioxide can be electrochemically reduced to valuable chemicals using electricity generated by wind or sunlight. This electroreduction of carbon dioxide presents scientists with a promising strategy for managing 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 electroreduction of carbon dioxide, scientists need efficient electrocatalysts. Electrocatalysts are the catalysts used in electrochemical reactions. They can increase the speed of the reaction that occurs. A research team from Nanjing University constructs catalysts using a fluorine doping method that improves their performance.
The research team reports its findings in Nano research.
Scientists know that cheap metal-nitrogen-carbon catalysts in one place work well for the electroreduction of carbon dioxide to carbon monoxide. Among them, nickel-nitrogen-doped carbon catalysts in one place have the high Faraday efficiency of carbon monoxide and high partial current. Faraada’s efficiency describes how efficiently charge is transferred in an electrochemical reaction.
The research team has already increased the efficiency of Farad and the high partial current of nickel- and nitrogen-alloyed carbon catalysts by alloying them. Compared to nickel-nitrogen-alloyed carbon catalysts in one place, one-place iron-nitrogen-carbon catalysts have lower excess potentials for electroreduction of carbon dioxide. The superpotential describes the effectiveness of the cell voltage. Previous studies have used fine-grained X-ray absorption spectroscopy to confirm that the active sites of iron-nitrogen-carbon single-catalysts are Fe3+ sites. These Fe3+ sites allow catalyst to be more efficient in carbon dioxide adsorption and carbon monoxide desorption.
The team constructs a one-site catalyst alloyed with fluorine, iron-nitrogen-carbon, which has more Fe3+ sites as expected. The one-site iron-nitrogen-carbon catalyst they construct, doped with fluorine, maintains the advantage of low superpotential. It also increased the efficiency of carbon monoxide in the farad from a high volcano-like value to a high plateau value. “The results show the excellent stability of fluorine-doped iron-nitrogen-carbon to iron-nitrogen-carbon due to fluorine doping,” said Lijun Yang, an associate professor at the School of Chemistry and Chemical Engineering, Nanjing University.
The research team concluded that electron-withdrawing fluorine doping allows the iron-nitrogen-carbon catalyst to maintain the advantage of a low superpotential, with much increased farad carbon monoxide efficiency and partial current density due to stabilized Fe3+ sites.
The team synthesized iron-nitrogen-carbon using a thermal method called adsorption pyrolysis. They conducted experiments on the electroreduction of carbon dioxide in an H-type cell and a cell with electrodes for gas diffusion. They used theoretical calculations to further understand the improvements that have occurred with fluoride doping.
“Electrochemical tests show that fluorinated doping-enriched defects kinetically increase the electroactive surface and improve charge transfer,” Young said. Looking ahead to further research, the results of their study provide a simple and controllable strategy for improving carbon dioxide electroreduction to the performance of carbon monoxide on iron-nitrogen-carbon catalysts by stabilization of Fe3+ sites.
Yiqun Chen et al, Increasing the faradic efficiency of electroreduction of CO2 to CO for catalysts with one Fe – N – C site by stabilizing Fe3 + sites by F-doping, Nano research (2022). DOI: 10.1007 / s12274-022-4441-0
Provided by Tsinghua University Press
Quote: Researchers use fluorine doping method to construct improved performance catalysts (2022, June 17), retrieved June 18, 2022 from https://phys.org/news/2022-06-fluorine-doping- method-catalysts.html
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