Browsing by Author "Aguirre, Maria Jesus"

Now showing 1 - 7 of 7
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    Determination of S(IV) Oxoanions at Poly[Ru(5-NO2-Phen)(2)Cl] Tetrapyridylporphyrin Glassy Carbon Modified Electrode
    (2012) Dreyse, Paulina A.; Quezada Sandoval, Diego Alonso; Honores Sotelo, Jessica Scarlet; Aguirre, Maria Jesus; Mendoza, Leonora; Matsuhiro, Betty; Villagra, Diego; Isaacs Casanova, Mauricio
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    Electrocatalytic reduction of nitrite on tetraruthenated metalloporphyrins/Nafion glassy carbon modified electrode
    (2011) Calfuman, Karla; Aguirre, Maria Jesus; Canete-Rosales, Paulina; Bollo, Soledad; Llusar, Rosa; Isaacs Casanova, Mauricio
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    Electrochemical reduction of nitrite at poly-[Ru(5-NO2-phen)(2)Cl] tetrapyridylporphyrin glassy carbon modified electrode
    (2011) Dreyse, Paulina A.; Isaacs Casanova, Mauricio; Calfuman, Karla; Caceres, Cesar; Aliaga, Alvaro; Aguirre, Maria Jesus; Villagra, Diego
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    First approach of fractals nickel-copper dendrites on stainless steel electrodes for ammonia oxidation to nitrogen monitored in operando by differential electrochemical mass spectroscopy
    (2024) Matamala-Troncoso, Felipe; Diaz-Coello, Sergio; Martinez, Francisco; Barrientos, Herna; Lisoni, Judit; Armijo, Francisco; Lozano, David; Pizarro, Jaime; Arevalo, Maria del Carmen; Pastor, Elena; Aguirre, Maria Jesus
    Fractal nickel-copper dendrites were synthesized by electrochemical deposition (ECD) on a stainless steel electrode (SS/NiCu). The electrode surface was characterized using Field Emission Scanning Electron Microscopy (FE-SEM), X-ray diffractometry (XRD), and Raman spectroscopy. The Ni-Cu molar ratio and the time applied in the ECD method were studied, revealing that both are critical factors in modifying and controlling the surface morphology. The SS/NiCu electrodes show a higher density current response when exposed to ammonium hydroxide, reaching a limiting current density at concentrations above 0.050 M NH4OH. 4 OH. Ammonia oxidation reaction (AOR) was monitored in operando using differential electrochemical mass spectroscopy (DEMS). When a bias potential over +1.50 V (vs. RHE) was applied, the evolution of oxygen and NO was observed. However, N2 2 was the only oxidation product at a constant potential below +1.50 V (vs. RHE). Oxygen (O2) 2 ) evolution was the main competitive reaction during the AOR. The results show that products are strongly dependent on the electrochemical perturbation applied. The study demonstrated that the SS/NiCu electrodes are suitable for AOR to N2 2 in high alkaline conditions.
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    Formation of a Conducting Polymer by Different Electrochemical Techniques and Their Effect on Obtaining an Immunosensor for Immunoglobulin G
    (2023) Martinez-Sade, Erika; Martinez-Rojas, Francisco; Ramos, Danilo; Aguirre, Maria Jesus; Armijo, Francisco
    In this work, a conducting polymer (CP) was obtained through three electrochemical procedures to study its effect on the development of an electrochemical immunosensor for the detection of immunoglobulin G (IgG-Ag) by square wave voltammetry (SWV). The glassy carbon electrode modified with poly indol-6-carboxylic acid (6-PICA) applied the cyclic voltammetry technique presented a more homogeneous size distribution of nanowires with greater adherence allowing the direct immobilization of the antibodies (IgG-Ab) to detect the biomarker IgG-Ag. Additionally, 6-PICA presents the most stable and reproducible electrochemical response used as an analytical signal for developing a label-free electrochemical immunosensor. The different steps in obtaining the electrochemical immunosensor were characterized by FESEM, FTIR, cyclic voltammetry, electrochemical impedance spectroscopy, and SWV. Optimal conditions to improve performance, stability, and reproducibility in the immunosensing platform were achieved. The prepared immunosensor has a linear detection range of 2.0-16.0 ng center dot mL(-1) with a low detection limit of 0.8 ng center dot mL(-1). The immunosensing platform performance depends on the orientation of the IgG-Ab, favoring the formation of the immuno-complex with an affinity constant (Ka) of 4.32 x 10(9) M-1, which has great potential to be used as point of care testing (POCT) device for the rapid detection of biomarkers.
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    Study of the reaction mechanism in hydrogen production using metal-free Schiff base as a catalyst
    (2023) Muena, Juan Pablo; Zamora, Pedro Pablo; Bieger, Klaus; Soliz, Alvaro; Haribabu, Jebiti; Aguirre, Maria Jesus; Marquez, Paulina; Quezada, Diego; Honores, Jessica
    Understanding the hydrogen evolution reaction and its mechanism is crucial for numerous practical applications in the realm of green energy. The development and discovery of new technologies or alternatives hold great significance in generating hydrogen at a low cost. In this study, we propose a novel catalyst, N, N'-bis(2-hydroxy1-naphthaldehyde)-o-phenylenediamine ([naph]2-o-ph), which is a Schiff base, for hydrogen production. The novelty lies in utilizing the organic Schiff base system and the proposed mechanism for hydrogen evolution, involving protonation and electron exchange on the Schiff base. Both experimental and theoretical results highlight the high capability of the Schiff base in generating hydrogen, providing valuable insights for potential applications in water electrolysis.
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    α-Fe2O3/, Co3O4/, and CoFe2O4/MWCNTs/Ionic Liquid Nanocomposites as High-Performance Electrocatalysts for the Electrocatalytic Hydrogen Evolution Reaction in a Neutral Medium
    (2024) Ibarra, Jose; Aguirre, Maria Jesus; del Rio, Rodrigo; Henriquez, Rodrigo; Faccio, Ricardo; Dalchiele, Enrique A.; Arce, Roxana; Ramirez, Galo
    Transition metal oxides are a great alternative to less expensive hydrogen evolution reaction (HER) catalysts. However, the lack of conductivity of these materials requires a conductor material to support them and improve the activity toward HER. On the other hand, carbon paste electrodes result in a versatile and cheap electrode with good activity and conductivity in electrocatalytic hydrogen production, especially when the carbonaceous material is agglomerated with ionic liquids. In the present work, an electrode composed of multi-walled carbon nanotubes (MWCNTs) and cobalt ferrite oxide (CoFe2O4) was prepared. These compounds were included on an electrode agglomerated with the ionic liquid N-octylpyridinium hexafluorophosphate (IL) to obtain the modified CoFe2O4/MWCNTs/IL nanocomposite electrode. To evaluate the behavior of each metal of the bimetallic oxide, this compound was compared to the behavior of MWCNTs/IL where a single monometallic iron or cobalt oxides were included (i.e., alpha-Fe2O3/MWCNTs/IL and Co3O4/MWCNTs/IL). The synthesis of the oxides has been characterized by X-ray diffraction (XRD), RAMAN spectroscopy, and field emission scanning electronic microscopy (FE-SEM), corroborating the nanometric character and the structure of the compounds. The CoFe2O4/MWCNTs/IL nanocomposite system presents excellent electrocatalytic activity toward HER with an onset potential of -270 mV vs. RHE, evidencing an increase in activity compared to monometallic oxides and exhibiting onset potentials of -530 mV and -540 mV for alpha-Fe2O3/MWCNTs/IL and Co3O4/MWCNTs/IL, respectively. Finally, the system studied presents excellent stability during the 5 h of electrolysis, producing 132 mu mol cm(-2) h(-1) of hydrogen gas.