Search

Your search keyword '"Réty, Bénédicte"' showing total 12 results
Start Over Author "Réty, Bénédicte"
12 results on '"Réty, Bénédicte"'

7. FeS 2 Nanoparticles in S-Doped Carbon: Ageing Effects on Performance as a Supercapacitor Electrode.

Author

Zallouz, Sirine, Réty, Bénédicte, Le Meins, Jean-Marc, Ndiaye, Mame Youssou, Fioux, Philippe, and Matei Ghimbeu, Camélia

Subjects
SUPERCAPACITOR performance, ELECTRODE performance, SUPERCAPACITOR electrodes, DETERIORATION of materials, DOPING agents (Chemistry)
Abstract

Although transition metal sulfides have prodigious potential for use as electrode materials because of their low electronegativities, their large volume changes inhibit broad application. Moreover, there is only limited knowledge of the ageing processes of these materials at the nanoscale. Herein, nano-C/FeS2 materials were prepared via one-pot syntheses from green biodegradable carbon precursors, followed by activation and sulfidation. The increased activation/sulfidation time led to an increase in the size of the nanoparticles (7 to 17 nm) and their aggregation, as well as in an increase in the specific surface area. The materials were then used as electrodes in 2-electrode symmetric supercapacitors with 2 M KOH. The activation process resulted in improved capacitance (60 F g−1 at 0.1 A g−1) and rate capability (36%) depending on the composite porosity, conductivity, and size of the FeS2 particles. The ageing of the FeS2 nanoparticles was investigated under air, and a progressive transformation of the nano-FeS2 into hydrated iron hydroxy sulfate with a significant morphological modification was observed, resulting in drastic decreases in the capacitance (70%) and retention. In contrast, the ageing of nano-FeS2 during cycling led to the formation of a supplementary iron oxyhydroxide phase, which contributed to the enhanced capacitance (57%) and long-term cycling (132% up to 10,000 cycles) of the device. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

12. Surface-Modified Activated Carbon with a Superior CH4/CO2Adsorption Selectivity for the Biogas Upgrading Process

Author

Peredo-Mancilla, Deneb, Matei Ghimbeu, Camelia, Réty, Bénédicte, Ho, Bich-Ngoc, Pino, David, Vaulot, Cyril, Hort, Cécile, and Bessieres, David

Abstract

The conversion of biogas to biomethane is an interesting alternative for clean energy production. Although biogas separation by physical adsorption using activated carbons has many advantages, the selectivity for CH4/CO2adsorption is fairly low. In this work, the surface chemistry of a commercial activated carbon (CNR-115) was modified by a two-step process: oxidative thermal treatment followed by ammonia modification. The activated carbons resulting from each modification step (CNR-115oxand CNR-115am, respectively) were characterized texturally and chemically, and their CH4/CO2equimolar mixture adsorption behaviors were measured. The results showed a significant loss of both surface area and porosity after the modification steps. However, the increased amount of polar surface functionalities leads to a remarkable increase of the selectivity factor (max. selectivity: 2.7 for CNR-115 < 23.4 for CNR-115ox< 129.0 for CNR-115am). The reasons behind the significantly enhanced selectivity are discussed on the basis of the surface chemistries and textural properties of the materials, in relation with molecule characteristics. We demonstrate herein a very efficient surface modification strategy, which allowed to obtain activated carbon adsorbents with oxygen and nitrogen groups that favor a superior CH4/CO2separation capacity. Furthermore, the stability of the added surface groups and the adsorption behavior was tested, proving the maintenance of the chemical characteristics and the adsorption performance after 10 adsorption/desorption cycles.

Published
2022
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results