Electrocatalysts for electrooxidation of direct alcohol fuel cell: Chemistry and applications

In the present scenario, civilization wholly depends on energy generation and storage for better technological progress and extension in several scientific applications. Owing to limited conventional energy sources and high energy requirement, absolute, cost-effective, and eco-friendly substitute roots of energy are of the principal interest. In this direction, direct alcohol fuel cell is becoming more familiar and promising because of its straightforward configuration system, weight, and elevated power generation efficiency. Indeed, recent years have seen extensive research on the preparation and properties of the fuel cell system. The literature review presented in this article provides comprehensive information on electrooxidation of alcohol developed on different type of electrocatalyst. The integration of a range of nanomaterials is depicted to comprehend the effect of different properties such as a well-ordered porous structure, exemplary high specific surface areas, electronic conductivity, tremendous convenience to active sites, and improved mass transport for electrooxidation of fuel cell. In this article, we have presented a detailed review of fuel cells and defined the main perspective, rationale and motivation, research tasks, and objectives of study as well as the delimitation of the study

Effect of Silver Modification on the Kinetics and Mechanisms of an Electrochemical Glycerol Oxidation Reaction at a Platinum Electrode in an Alkaline Medium

ACS Applied Energy Materials. 2024, 7 (5), P.1970-1982journal articl

Effect of the air pressure on electro-Fenton process

Electro-Fenton process is considered a very promising tool for the treatment of waste waters contaminated by organic pollutants refractant or toxic for microorganisms used in biological processes [1-6]. In these processes H2O2 is continuously supplied to an acidic aqueous solution contained in an electrolytic cell from the two-electron reduction of oxygen gas, directly injected as pure gas or bubbled air. Due to the poor solubility of O2 in aqueous solutions, two dimensional cheap graphite or carbon felt electrodes give quite slow generation of H2O2, thus resulting in a slow abatement of organics. In this context, we report here a series of studies [7-9] on the effect of air pressure on the electro-generation of H2O2 and the abatement of organic pollutants in water by electro-Fenton process. The effect of air pressure, current density, mixing and nature of the organic pollutant was evaluated. [1] E. Brillas, I. Sirés, M.A. Oturan, Chem. Rev., 109 (2009) 6570-6631. [2] C.A. Martínez-Huitle, M.A. Rodrigo, I. Sirés, O. Scialdone, Chem. Rev. 115 (2015) 13362–13407. [3] M. Panizza, G. Cerisola, Chem. Rev. 109 (2009) 6541–6569. [4] I. Sirés, E. Brillas, M.A. Oturan, M.A. Rodrigo, M. Panizza, Environ. Sci. Pollut. Res. 21 (2014) 8336–8367. [5] C.A. Martínez-Huitle, S. Ferro, Chem. Soc. Rev. 35 (2006) 1324–1340. [6] B.P.P. Chaplin, Environ. Sci. Process. Impacts. 16 (2014) 1182–1203. [7] O. Scialdone, A. Galia, C. Gattuso, S. Sabatino, B. Schiavo, Electrochim. Acta, 182 (2015) 775-780. [8] J.F. Pérez, A. Galia, M.A. Rodrigo, J. Llanos, S. Sabatino, C. Sáez, B. Schiavo, O. Scialdone, Electrochim. Acta, 248 (2017) 169-177. [9] A.H. Ltaïef, S. Sabatino, F. Proietto, A. Galia, O. Scialdone, O. 2018, Chemosphere, 202, 111-118

Pressurized CO2 Electrochemical Conversion to Formic Acid: From Theoretical Model to Experimental Results

To curb the severely rising levels of carbon dioxide in the atmosphere, new approaches to capture and utilize this greenhouse gas are currently being investigated. In the last few years, many researches have focused on the electrochemical conversion of CO2 to added-value products in aqueous electrolyte solutions. In this backdrop, the pressurized electroreduction of CO2 can be assumed an up-and-coming alternative process for the production of valuable organic chemicals [1-3]. In this work, the process was studied in an undivided cell with tin cathode in order to produce formic acid and develop a theoretical model, predicting the effect of several operative parameters. The model is based on the cathodic conversion of pressurized CO2 to HCOOH and it also accounts for its anodic oxidation. In particular, the electrochemical reduction of CO2 to formic acid was performed in pressurized filter press cell with a continuous recirculation of electrolytic solution (0.9 L) at a tin cathode (9 cm2) for a long time (charge passed 67’000 C). It was shown that it is possible to scale-up the process by maintaining good results in terms of faradaic efficiency and generating significantly high concentrations of HCOOH (about 0.4 M) [4]. It was also demonstrated that, for pressurized systems, the process is under the mixed kinetic control of mass transfer of CO2 and the reduction of adsorbed CO2 (described by the Langmuir equation), following our proposed reaction mechanism [5]. Moreover, the theoretical model is in good agreement with the experimental results collected and well describes the effect of several operating parameters, including current density, pressure, and the type of reactor used. 1. Ma, S., & Kenis, P. J. (2013). Electrochemical conversion of CO2 to useful chemicals: current status, remaining challenges, and future opportunities. Current Opinion in Chemical Engineering, 2(2), 191-199. 2. Endrődi, B., Bencsik, G., Darvas, F., Jones, R., Rajeshwar, K., & Janáky, C. (2017). Continuous-flow electroreduction of carbon dioxide. Progress in Energy and Combustion Science, 62, 133-154. 3. Dufek, E. J., Lister, T. E., Stone, S. G., & McIlwain, M. E. (2012). Operation of a pressurized system for continuous reduction of CO2. Journal of The Electrochemical Society, 159(9), F514-F517. 4. Proietto, F., Schiavo, B., Galia, A., & Scialdone, O. (2018). Electrochemical conversion of CO2 to HCOOH at tin cathode in a pressurized undivided filter-press cell. Electrochimica Acta, 277, 30-40. 5. Proietto, F., Galia, A., & Scialdone, O. (2019) Electrochemical conversion of CO2 to HCOOH at tin cathode: development of a theoretical model and comparison with experimental results. ChemElectroChem, 6, 162-172

Multifunctional oxidation electrocatalysts for direct alkaline fuel cells

The need for the development of new technologies to reduce our dependence on fossil fuels requires the combination of different energy sources such as wind, solar, nuclear as well as new energy storage and powering devices. Amongst these new technologies fuel cells are a promising technology capable of transforming chemical energy stored in fuels into electric power at higher efficiencies than combustion processes. However, the commercialization of fuel cells has been limited due to the high costs associated with electrocatalysts needed for the corrosive environments in which proton-exchange membrane fuel cells operate. Electrocatalysts for such fuel cells are based on expensive noble metals such as platinum. Nevertheless, the resurging interest on the development of alkaline fuel cells presents a number of advantages addressing the limitations of proton-exchange membrane fuel cells. Alkaline fuel cells operate at high pHs which allow the use of a wider variety of inexpensive and abundant materials such as transition and rare-earth metals. Moreover, faster kinetics have been reported in alkaline environments for both oxidation and reduction processes occurring at each of the electrodes. The discussion related to the first part of this dissertation focuses on the development of novel electrocatalysts for the oxidation of hydrazine for application in direct hydrazine alkaline fuel cells. Hydrazine is a carbon-free nontraditional fuel with high energy density (5kWh/kg), which is often considered a green fuel since its oxidation only produces nitrogen and water and does not contribute to the production of greenhouse gases emissions. It has been reported that transition metal catalysts such as Ni and Co demonstrate better performances than the commonly used Pt catalyst. Based on these preliminary findings, we have developed novel electrocatalysts with enhanced performance due to the addition of a second metal. α-NiZn electrocatalysts have shown improved performance due to an intrinsic effect cause by the alloying of an electron-dense atom such as Zn with Ni. Moreover, enhanced performance was also observed by the addition of a second phase, La(OH)3. La(OH)3 promotes the catalytic oxidation of hydrazine by providing oxygen species to the surface of the electrode for the dehydrogenation of hydrazine. Extensive ex situ characterization of materials using a number of different electron microscopy and X-ray spectroscopy techniques in combination with in situ electrochemical infrared studies provided insightful knowledge about the role of the components in the mechanism of the reaction. The knowledge gained from the studies performed for the development catalyst for hydrazine oxidation was applied to a more complex reaction, the electrooxidation of ethanol in alkaline media. Complex kinetics have been reported for the oxidation reaction of ethanol resulting in only a partial oxidation producing acetate. Highly active Pd/SnO2 catalysts were developed with three times the performance of Pd. Moreover, thorough understanding of the mechanisms of the ethanol reaction at different electrolyte concentrations was carried out using in situ infrared studies. Results show that better performances were obtained at 1 M KOH, but ethanol only partially oxidized to acetate. On the other hand, when the concentration of the electrolyte was reduced to 0.1 M KOH complete oxidation of ethanol to CO2 was observed. However, this resulted in higher overpotentials and lower rate constants. Mechanistic studies of reactions in both electrolytes concluded that higher concentrations of electrolyte allow for the oxidation of ethanol to occur at lower overpotentials due to the availability of hydroxide ions at the surface of the electrode, which participate in the oxidation of the adsorbed ethanol species. On the other hand, by the decreasing the concentration of electrolyte, diffusion of the hydroxide ions to the surface of the electrode is limited allowing the oxidation of ethanol to proceed to completion without desorbing the intermediate acetate product

Softwood Kraft Pulp-Derived Carbon-Supported PtNi Catalysts for the Electrooxidation of Ethanol

In this work, the biocarbons synthesized by fast pyrolysis at 350°C of raw (BK) and H3PO4 treated (TBK) fibrous fraction of non-bleached softwood kraft pulp has been proposed as novel supports for the deposition of PtNi nanocatalysts. The bimetallic nanoparticles were deposited by pulse microwave-assisted reduction using ethylene glycol both as solvent and reducing agent. The physicochemical properties of the resulting materials were evaluated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray microanalysis (EDX) and inductively coupled plasma atomic emission spectroscopy (ICP-AES), whereas the electrochemical activity towards ethanol oxidation in acid medium was evaluated using cyclic voltammetry (CV) and chronoamperometry (CA). Nanosized PtNi particles with average diameters in the range of 2.9-4.1 nm and a nickel content of ca. 30 at. % were deposited over both softwood kraft pulp-derived carbon materials. The electrochemical measurements showed that the bimetallic nanoparticles deposited over the acid-treated biocarbon (PtNi/TBK) exhibit superior catalytic performance in terms of activity, onset potential, and poisoning tolerance. The mass activity of the PtNi nanocatalyst supported over TBK was about 1.3 and 6.3 times higher than that of the bimetallic nanoparticles deposited onto BK and Pt/C, respectively. The effect of the carbonaceous material on the electrocatalytic activity is discussed in detail.Fil: Nieva Lobos, María Luz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Sieben, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; ArgentinaFil: Moyano, Elizabeth Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin