DQIO-Artículos
URI permanente para esta colecciónhttps://hdl.handle.net/10953/280
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Examinando DQIO-Artículos por Autor "Domingo-García, María"
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Ítem Expanding graphene properties by a simple S-doping methodology based on cold CS2 plasma(Elsevier, 2019-12-14) Abdelkader-Fernández, Victor Karim; Domingo-García, María; López Garzón, Francisco Javier; Fernandes, Diana M.; Freire, Cristina; López de la Torre, Maria Dolores; Melguizo, Manuel; Godino-Salido, Maria Luz; Pérez-Mendoza, ManuelFor the first time, graphene has been successfully doped with sulfur via short exposition to CS2 microwave cold plasmas, avoiding high-temperature and time/chemicals-consuming treatments. Different S-doped samples were obtained by varying the duration of plasma treatments, reaching a remarkable 2.3 at % of S content after only 5 min of exposition. The S-doped graphenes present several sulfur containing moieties, among which thioether groups resulted to be predominant. These moieties are covalently bond to graphene layers and exhibit good thermal and water stability. In addition, unlike others more conventional methods, S-doping via CS2 plasmas do not damage the structural order of graphene. The influence of sulfur doping on the graphene properties has been assessed through two different tests: on one side, the capture of Pd2+ ions in aqueous solution, and on the other, the electrocatalytic activity towards the production of oxygen from water (OER process). In both cases, the performance of the pristine graphene was significantly enhanced with S-doping. In addition, the capture of Pd2+ allows the formation of sulfur-Pd nanoclusters supported on the graphene surface, which are very useful in electrochemical devices.Ítem HBPEI-grafted carbon nanotubes for the effective retention of Pd2+ and Pt2+ through complexation(Royal Society of Chemistry, 2018-06-21) Abdelkader-Fernández, Victor Karim; Morales-Lara, Francisco; López de la Torre, Maria Dolores; Melguizo, Manuel; López Garzón, Francisco Javier; Domingo-García, María; Pérez-Mendoza, ManuelHyperbranched poly(ethyleneimine) (HBPEI) molecules in solution present high capacity to form stable complexes with transition metal ions due to the large number of amino groups ready to form chelates. We grafted HBPEI molecules to a multi-walled carbon nanotube (MWCNT) surface through covalent bonding, preparing solid hybrids which retain the chemical properties of the free poly-alkylamine molecules. In this way, we are able to transfer the complexation capacity of such molecules to a solid material adequate to act as a high-capacity sorbent for metal transition ions. We tested the HBPEI/MWCNT hybrids for the retention of Pd2+ and Pt2+ and the retention values obtained are much larger than those previously reported with fast retention kinetics. The kinetics and the XPS analysis of the metal ion/HBPEI/MWCNT ensemble indicate that the retention takes place through the formation of chelates with two or three nitrogen atoms and with Cl− anions as co-ligands. Moreover, the results allow us to tune the metal loading on the hybrids by controlling the solution conditions. This is important because the XPS valence band analysis demonstrates that metal complexation directly modifies the electronic behaviour of the carbon nanotubes, which supports the stable covalent bond between HBPEI molecules and MWCNT and opens the possibility for tuning the electronic properties of the tubes.