Electrochemical study of H3PMo12 retention on Vulcan carbon grafted with NH2 and OH groups

In this work, we show a comparative study based on the effects of specific chemical functional groups (–OH, –NH2), grafted on Vulcan carbon (VC) with the incorporation of a specific polyoxometalate (POM), PMo12 (H3PMo12O40), to improve electrochemical performance. We observed a decrease in the specific surface area of the grafted matrices (VC-OH and VC-NH2) [1], and the same trend was observed for PMo12 (POM) incorporation. Our electrochemical studies showed low concentrations of POM in unmodified VCs and higher POM concentrations for grafted matrices (VC-OH and VC-NH2) after 500 voltammetric cycles, especially for the VC grafted with –OH groups (VC-OH-POM). Mechanisms have been proposed for POM interaction with the grafted groups in carbon, emphasizing the role of aqueous medium and redox activity of POM. Cyclic voltammograms suggested the POM anchoring through –OH groups with a strong interaction as a covalent bond, resulting in a surface coverage of 1.66 × 10−11 mol cm−2. Surface modifications could be extrapolated to other carbons, and the materials could be employed for different potential applications such as photocatalysis, amperometric sensors, fuel cells, and supercapacitors.Fil: Cuentas Gallegos, Ana Karina. Universidad Nacional Autónoma de México; México. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: López Cortina, S.. Universidad Autonoma de Nuevo Leon; MéxicoFil: Brousse, T.. Université de Nantes. Institut Des Materiaux Jean Rouxel; FranciaFil: Pacheco Catalán, D.. Centro de Investigación Científica de Yucatán; MéxicoFil: Fuentes Quezada, Eduardo. Centro de Investigación y Desarrollo Tecnológico en Electroquímica; México. Universidad Nacional Autónoma de México; México. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mosqueda, H.. Universidad Autonoma de Nuevo Leon; MéxicoFil: Orozco Gamboa, G.. Centro de Investigación y Desarrollo Tecnológico en Electroquímica; Méxic

Organic/inorganic hybrid materials based on conducting organic polymers as electrodes for energy storage devices : tesis doctoral /

Consultable des del TDXA portada: Laboratorio de Química del Estado Sólido. Instituto de Ciencia de MaterialesTítol obtingut de la portada digitalitzadaVegeu akcgresum1de1.pd

Feasibility of the Redox Sulfur Recovery Process using Heteropoly Molybdophosphate

The feasibility of the removal of sulfide species using acid solutions of 12-molybdophosphoric acid was studied. The key factor in this purification process is the formation of a hydrogen-bonded structure between the hydrogen sulfide species and the bridging oxygen atom of the MoO6 octahedrons of the molybdophosphate complexes. The number of bridging oxygen atoms depends of the pH. Consequently, the efficiency of the process is also largely dependent on the pH. Most of the literature focuses on the redox potentials for the purification process. The slope of the redox pair S/H2S and the molybdophosphate complexes is -59 pH/mV. The differences between the redox potentials do not fluctuate with the pH, which indicates that the oxidation of H2S by molybdophosphate complexes is spontaneous in all pH intervals but does not explain why the efficiency decreases at high pH. In summary, the Keggin-type structure contributes to the efficient removal of sulfide because this structure contains the maximum number of bridging oxygen atoms. The solubility of H2S gas is lower in acidic media. This drawback severely restricts the performance of the purification process.Fil: Fuentes Quezada, Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Centro de Investigación y Desarrollo Tecnológico en Electroquímica; MéxicoFil: Cuentas Gallegos, Ana Karina. Universidad Nacional Autónoma de México; MéxicoFil: Rivera Garat, Julio Ernesto. Centro de Investigación y Desarrollo Tecnológico en Electroquímica; MéxicoFil: Castañeda, F. Centro de Investigación y Desarrollo Tecnológico en Electroquímica; MéxicoFil: Orozco Gamboa, G. Centro de Investigación y Desarrollo Tecnológico en Electroquímica; Méxic