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Search results for: electrocatalysts
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Advanced XAS analysis for investigating fuel cell electrocatalysts
PublicationW pracy została zaprezentowana analiza XAFS nanocząstek platyny używanych jako materiał katalityczny w niskotemperaturowych ogniwach paliwowych. Analiza danych EXAFS została przeprowadzona za pomocą zaawansowanej metody GNXAS, w której wzięto pod uwagę rozkład rozmiaru granul nano-platyny i niejednorodność warstwy katalitycznej elektrody, badane za pomocą SEM (skaningowy mikroskop elektronowy), TEM (transmisyjny mikroskop elektronowy)...
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Fe local structure in Pt-free nitrogen-modified carbon based electrocatalysts: XAFS study
PublicationThe paper presents a new results on the bonding environment (coordination number and geometry) and on oxidation states of Fe in nitrogen-modified Fe/C composites used as Pt-free catalysts for oxygen reduction in Direct Hydrogen Fuel Cells. Starting from glucose or fructose, two catalysts displaying different electrochemical performance were prepared and studied in the form of pristine powder and thin catalytic layer of electrode...
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Investigating Layered Topological Magnetic Materials as Efficient Electrocatalysts for the Hydrogen Evolution Reaction under High Current Densities
PublicationDespite considerable progress, high-performing durable catalysts operating under large current densities (i.e., >1000 mA/cm2) are still lacking. To discover platinum group metal-free (PGMfree) electrocatalysts for sustainable energy, our research involves investigating layered topological magnetic materials (semiconducting ferromagnets) as highly efficient electrocatalysts for the hydrogen evolution reaction under high current...
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Dicyandiamide-assisted synthesis of N-doped porous CoMn–Nx@N–C carbon nanotube compositesviaMOFs as efficient trifunctional electrocatalysts in the same electrolyte
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Evolution of the nanostructure of Pt and Pt–Co polymer electrolyte membrane fuel cell electrocatalysts at successive degradation stages probed by X-ray photoemission
PublicationWe present a set of XPS (X-ray photoemission spectroscopy) measurements and detailed data-analysis of electrodes for polymer electrolyte membrane fuel cell (PEMFC) based on carbon supported catalysts (Pt and Pt–Co) subjected to a step-like potential cycling (accelerated degradation test). The results of the measurements complete and corroborate parallel TEM (transmission electron microscopy), XRD (X-ray diffraction) and XAS (X-ray...
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Powering the Future by Iron Sulfide Type Material (FexSy) Based Electrochemical Materials for Water Splitting and Energy Storage Applications: A Review
PublicationWater electrolysis is among the recent alternatives for generating clean fuels (hydrogen). It is an efficient way to produce pure hydrogen at a rapid pace with no unwanted by-products. Effective and cheap water-splitting electrocatalysts with enhanced activity, specificity, and stability are currently widely studied. In this regard, noble metal-free transition metal-based catalysts are of high interest. Iron sulfide (FeS) is one...
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Sub‐Nanometer‐Scale Cu9S5 Enables Efficiently Electrochemical Nitrate Reduction to Ammonia
PublicationThe sub-nanometer is a key feature size in materials science. Unlike single-atom and nanomaterials, size effects and inter-component cooperative actions in sub-nanomaterials will effective on its performance is more significant. Here, 0.95 nm ordered arrangement Cu9S5 sub-nanowires (Cu9S5 SNWs) are synthesized through the co-assembly effect of inorganic nuclei (Cu9S5) and clusters (phosphotungstic acid-PTA), achieving a significant...
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The role of aluminium in metal–organic frameworks derived carbon doped with cobalt in electrocatalytic oxygen evolution reaction
PublicationWater electrolysis is one of the most crucial processes in the development of new energy sources, where ultra-clean fuel is produced - hydrogen. Oxygen evolution reaction (OER) is the sluggish process of overall water splitting. Therefore, this study presents the design, characterization and electrochemical study of cobalt-based electrocatalysts embedded into porous carbons derived from an Al-metal–organic...
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Enhanced Electrochemical Performance of MnCo1.5Fe0.5O4Spinel for Oxygen Evolution Reaction through Heat Treatment
PublicationMnCo1.5Fe0.5O4 spinel oxide was synthesized using the sol−gel technique, followed by heat treatment at various temperatures (400, 600, 800, and 1000 °C). The prepared materials were examined as anode electrocatalysts for watersplitting systems in alkaline environments. Solid-state characterization methods, such as powder X-ray diffraction and X-ray absorption spectroscopy (XAS), were used to analyze the materials’ crystallographic...
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Cathodic Activation of Titania-Fly Ash Cenospheres for Efficient Electrochemical Hydrogen Production: A Proposed Solution to Treat Fly Ash Waste
PublicationFly ash (FA) is a waste product generated in huge amounts by coal-fired electric and steam-generating plants. As a result, the use of FA alone or in conjunction with other materials is an intriguing study topic worth exploring. Herein, we used FA waste in conjunction with titanium oxide (TiO2) to create (FA-TiO2) nanocomposites. For the first time, a cathodic polarization pre-treatment regime was applied to such nanocomposites...
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A Comprehensive Analysis of Impedance of the Electrochemical Cell
PublicationA comprehensive impedance characteristics of two electrodes electrochemical cell has been pre sented. In this method a multisinusoidal current excitation signal is used. The change of potential of both the electrodes are all registered as a function of time. The proposed method gives the possibility of determining the impedance of both electrodes individually as well as the impedance of a twoelectrode system. Additional application...
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Modification of TiO2 nanotubes by graphene–strontium and cobalt molybdate perovskite for efficient hydrogen evolution reaction in acidic medium
PublicationHerein, we demonstrate that modification of TiO2 nanotubes with graphene–strontium and cobalt molybdate perovskite can turn them into active electrocatalysts for hydrogen evolution reaction (HER). For this purpose, a simple method of hydrothermal synthesis of perovskites was developed directly on the TiO2 nanotubes substrate. Moreover, the obtained hybrids were also decorated with graphene oxide (GO) during one-step hydrothermal...
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Tuning the work function of graphite nanoparticles via edge termination
PublicationGraphite nanoparticles are important in energy materials applications such as lithium-ion batteries (LIBs), supercapacitors and as catalyst supports. Tuning the work function of the nanoparticles allows local control of lithiation behaviour in LIBs, and the potential of zero charge of electrocatalysts and supercapacitors. Using large scale density functional theory (DFT) calculations, we find that the surface termination of multilayer...
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Free-standing TiO2 nanotubes decorated with spherical nickel nanoparticles as a cost-efficient electrocatalyst for oxygen evolution reaction
PublicationHere, we report significant activity towards the oxygen evolution reaction (OER) of spherical nickel nanoparticles (NPs) electrodeposited onto free-standing TiO2 nanotubes (TNT) via cyclic voltammetry. It has been shown that simple manipulation of processing parameters, including scan rate and number of cycles, allows for formation of the NPs in various diameters and amounts. The polarization data with respect to transmission electron...
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MnxCo3-xO4 spinel oxides as efficient oxygen evolution reaction catalysts in alkaline media
PublicationThe design of efficient electrocatalysts for oxygen evolution reaction (OER) is an essential task in developing sustainable water splitting technology for the production of hydrogen. In this work, manganese cobalt spinel oxides with a general formula of MnxCo3-xO4 (x=0, 0.5, 1, 1.5, 2) were synthesised via a soft chemistry method. Non-equilibrium mixed powder compositions were produced, resulting in high electrocatalytic activity....
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Combined effect of nitrogen-doped carbon and NiCo2O4 for electrochemical water splitting
PublicationElectrocatalytic water splitting for green hydrogen production necessitates effective electrocatalysts. Currently, commercial catalysts are primarily platinum-based. Therefore, finding catalysts with comparable catalytic activity but lower cost is essential. This paper describes spinel-structured catalysts containing nickel cobaltite NiCo2O4, graphene, and additionally doped with heteroatoms. The structure and elemental composition...
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Nickel-based catalysts for electrolytic decomposition of ammonia towards hydrogen production
PublicationNickel is an attractive metal for electrochemical applications because it is abundant, cheap, chemically resilient, and catalytically active towards many reactions. Nickel-based materials (metallic nickel, its alloys, oxides, hydroxides, and composites) have been also considered as promising electrocatalysts for ammonia oxidation. The electrolysis of ammonia aqueous solution results in evolution of gaseous hydrogen and nitrogen....
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Salt melt synthesis of curved nitrogen-doped carbon nanostructures: ORR kinetics boost
PublicationImplementing metal-free electrocatalysts for the oxygen reduction reaction (ORR) and revealing crucial chemical or topographical parameters driving their activity are vital for the development of power cells. The carbon-based catalysts are very often synthesized through carbonization of biopolymers, in particular, those one containing nitrogen groups such as chitosan. Unfortunately, the resulting carbonaceous materials usually...
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AlP compound and P-doping for promotion of electrocatalytic activity of N-doped carbon derived from metal-organic framework
PublicationWater splitting plays a key role in future fuels, where two processes occur - the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Nitrogen-doped carbon derived from...
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Methods and Instruments | Scanning Electrochemical Microscopy
PublicationScanning electrochemical microscopy is based on the recording of electrolysis currents (Faradaic currents) at a microelectrode (ME) probe that is scanned over the sample. Different working modes are available to couple the electrolysis at the ME to reactions at the sample. The article explains their principles and provides examples of their application. The feedback mode, the sample-generation/tip collection mode, the redox-competition...
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Evaluation of electrosynthesized reduced graphene oxide–Ni/Fe/Co-based (oxy)hydroxide catalysts towards the oxygen evolution reaction
PublicationIn this work, the specific role of the addition of graphene oxide (GO) to state-of-the-art nickel–iron (NiFe) and cobalt–nickel–iron (CoNiFe) mixed oxides/hydroxides towards the oxygen evolution reaction (OER) is investigated. Morphology, structure, and OER catalytic activity of the catalysts with and without GO were studied. The catalysts were fabricated via a two-step electrodeposition. The first step included the deposition...
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Tuning of eg electron occupancy of MnCo2O4 spinel for oxygen evolution reaction by partial substitution of Co by Fe at octahedral sites
PublicationTo study the effect of partial Co substitution by Fe in the B site of MnCo2O4 spinel on its physicochemical and electrochemical properties, a series of MnCo2-xFexO4 powders (x=0.125; 0.250; 0.500; 0.750; 1.000) were synthesized by means of the sol-gel method. The produced powders were characterized by powder X ray diffraction (pXRD), scanning and transmission electron microscopy (SEM & TEM) coupled with energy dispersive spectroscopy...
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Microporous N-Doped Carbon Obtained from Salt Melt Pyrolysis of Chitosan toward Supercapacitor and Oxygen Reduction Catalysts
PublicationThe direct carbonization of low-cost and abundant chitosan biopolymer in the presencesalt eutectics leads to highly microporous, N-doped nanostructures. The microporous structureeasily manufactured using eutectic mixture (ZnCl2 -KCl) and chitosan. Potassium ions here can act as an intercalating agent, leading to the formation of lamellar carbon sheets, whereas zinc chloride generates significant porosity. Here, we present an efficient...
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The effect of Fe on chemical stability and oxygen evolution performance of high surface area SrTix-1FexO3-δ mixed ionic-electronic conductors in alkaline media
PublicationDevelopment of environmentally friendly, high performing oxygen evolution reaction (OER) catalysts is an important research challenge. In this work, iron doped strontium titanates with a general formula SrTi1-xFexO3-δ (x = 0.35, 0.50, 0.70, 0.90, and 1.00) denoted as STFx, were synthesized via a solid state reaction technique and characterized in terms of oxygen evolution reaction electrocatalysis in an alkaline electrolyte (0.1...