Highly graphitic Fe-doped carbon xerogels as dual-functional electro-Fenton catalysts for the degradation of tetracycline in wastewater

Fe-doped carbon xerogels with a highly developed graphitic structure were synthesized by a one-step sol-gel polymerization. These highly graphitic Fe-doped carbons are presented as promising dual-functional electro-Fenton catalysts to perform both the electro-reduction of O2 to H2O2 and H2O2 catalytic decomposition (Fenton) for wastewater decontamination. The amount of Fe is key to the development of this electrode material, since affects the textural properties; catalyzes the development of graphitic clusters improving the electrode conductivity; and influences the O2-catalyst interaction controlling the H2O2 selectivity but, at the same time is the catalyst for the decomposition of the electrogenerated H2O2 to OH• radicals for the organic pollutants oxidation. All materials achieve the development of ORR via the 2-electron route. The presence of Fe considerably improves the electro-catalytic activity. However, a mechanism change seems to occur at around −0.5 V in highly Fe-doped samples. At potential lower than −0.5 eV, the present of Feδ+ species or even Fe–O–C active sites favour the selectivity to 2e-pathway, however at higher potentials, Feδ+ species are reduced favoring a O–O strong interaction enhancing the 4e-pathway. The Electro-Fenton degradation of tetracycline was analyzed. The TTC degradation is almost complete (95.13%) after 7 h of reaction without using any external Fenton-catalysts.Grupo RNM-172Universidad de Granada / CBUAMCIN/AEI/10.13039/501100011033/ y "ERDF A way of making Europe” (PID2021-127803OB-I00)Junta de Andalucía (P18-RTJ-2974 y B. RNM.566. UGR20

Influence of Surface Chemistry on the Electrochemical Performance of Biomass-Derived Carbon Electrodes for its Use as Supercapacitors

Activated carbons prepared by chemical activation from three different types of waste woods were treated with four agents: melamine, ammonium carbamate, nitric acid, and ammonium persulfate, for the introduction of nitrogen and oxygen groups on the surface of materials. The results indicate that the presence of the heteroatoms enhances the capacitance, energy density, and power density of all samples. The samples treated with ammonium persulfate show the maximum of capacitance of 290 F g−1 while for the melamine, ammonium carbamate, and nitric acid treatments, the samples reached the maximum capacitances values of 283, 280, and 455 F g−1 respectively. This remarkable electro-chemical performance, as the high specific capacitances can be due to several reasons: i) The excellent and adequate textural characteristics makes possible a large adsorption interface for electrolyte to form the electrical double layer, leading to a great electrochemical double layer capacitance. ii) The doping with hetero-atoms enhances the surface interaction of these materials with the aqueous electrolyte, increasing the accessibility of electrolyte ions. iii) The hetero-atoms groups can also provide considerable pseudo-capacitance improving the overall capacitance

Electrodos basados en carbón obtenidos a partir de residuos agrícolas y geles de carbono para supercondensadores y electro-reducción de oxígeno

En la presente Tesis Doctoral se han preparado y caracterizado diferentes series de materiales basados en carbono, tanto carbones activados como materiales compuestos óxido metálico - xerogel de carbón. Estos materiales se obtuvieron mediante activación con KOH y H3PO4 de diferentes residuos agrícolas tales como maderas de olivo, higuera y chirimoya, además se ha empleado como material de partida un residuo de la industria oleícola, el alperujo, subproducto obtenido durante el sistema continuo de extracción de dos fases y que consiste de una mezcla de alpechín y orujo. Se trata de un residuo altamente contaminante que, según las actuales normativas medioambientales, debe ser separado antes de destinarlo a cualquier uso como la obtención de energía. Por otra parte, se han sintetizado también materiales compuestos óxidos metálicos - xerogel de carbón, seleccionándose los óxidos: TiO2, ZrO2 y V2O5. Los materiales preparados han sido caracterizados química y texturalmente, y empleados como electrodos de condensadores electroquímicos para el almacenamiento de energía eléctrica en forma electrostática, y en la reacción de electro-reducción de O2.Tesis Univ. Granada. Programa Oficial de Doctorado en QuímicaEste Trabajo de Investigación ha sido financiado por la Junta de Andalucía, a través del Grupo de Investigación RNM-172 y del Proyecto de Excelencia P12- RNM-2892; y también por el Ministerio de Economía y Competitividad y fondos FEDER a través del Proyecto Retos CTQ2013-44789-R. Igualmente, Abdelhakim Elmouwahidi agradece al Programa ERASMUS MUNDUS la concesión de una beca Al Idrisi, Acción 2, Lote 1