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1.
Iron phosphide electrocatalyst for renewable production of value-added products
Takwa Chouki, Manel Machreki, Iwona A. Rutkowska, Beata Rytelewska, Pawel Jozef Kulesza, Georgi Tyuliev, Moussab Harb, Luis Miguel Azofra, Saim Emin, 2022, objavljeni povzetek znanstvenega prispevka na konferenci (vabljeno predavanje)

Opis: The electrochemical reduction reaction of the nitrate ion (NO3) to valuable ammonia (NH3) is a promising green approach. Herein, we report for the the electrocatalytic reduction of NO3 using different phases of iron phosphide. Particularly, FeP and Fe2P phases were successfully demonstrated as efficient catalysts for NH3 generation. The Fe2P catalyst exhibits the highest Faradaic efficiency (96%) for NH3 generation with a yield (0.25 mmol h−1 cm-−2) at −0.55 V vs. reversible hydrogen electrode (RHE). The recycling tests confirmed that Fe2P and FeP catalysts exhibit excellent stability during the NO3 reduction at −0.37 V vs. RHE. These results indicate that the Fe2P phase exhibits excellent performance to be deployed as an efficient noble metal-free catalyst for NH3 generation. In addition to NO3 reduction the iron phosphide phases were used in electrocatalytic H2 generation using water electrolysis. The electrocatalytic activities of heat-treated Fe2P−450°C, Fe3P−500°C, and Fe2P/FeP−500°C catalysts were studied for hydrogen evolution reaction (HER) in 0.5 M H2SO4. The lowest electrode potential of 110 mV vs. a reversible hydrogen electrode (RHE) at 10 mA cm−2 was achieved with a mixed Fe2P/FeP−500°C catalyst.
Ključne besede: electrochemical reduction, nitrate reduction, iron phosphide catalyst, NH3 generation
Objavljeno v RUNG: 10.01.2025; Ogledov: 330; Prenosov: 2
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2.
Iron phosphide catalysts for electrochemical energy conversion
Takwa Chouki, Manel Machreki, Romana Cerc Korošec, Urška Lavrenčič Štangar, Saim Emin, 2024, objavljeni povzetek znanstvenega prispevka na konferenci

Ključne besede: electrocatalysts, e iron phosphide catalyst
Objavljeno v RUNG: 08.01.2025; Ogledov: 319; Prenosov: 0
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3.
Efficient electrochemical nitrogen fixation at iron phosphide (Fe_2P) catalyst in alkaline medium
Beata Rytelewska, Anna Chmielnicka, Takwa Chouki, Magdalena Skunik-Nuckowka, Shaghayegh Naghdi, Dominik Eder, Aleksandra Michalowska, Tomasz Ratajczyk, Egon Pavlica, Saim Emin, 2023, izvirni znanstveni članek

Opis: A catalytic system based on iron phosphide (Fe2P) has exhibited electrocatalytic activity toward N2-reduction reaction in alkaline medium (0.5 mol dm−3 NaOH). Based on voltammetric stripping-type electroanalytical measurements, Raman spectroscopic and spectrophotometric data, it can be stated that the Fe2P catalyst facilitates conversion of N2 to NH3, and the process is fairly selective with respect to the competing hydrogen evolution. A series of diagnostic electrocatalytic experiments (utilizing platinum nanoparticles and HKUST-1) have been proposed and performed to control purity of nitrogen gas and to probe presence of potential contaminants such as ammonia, nitrogen oxo-species and oxygen. On the whole, the results are consistent with the view that the interfacial reduced-iron (Fe0) centers, while existing within the network of P sites, induce activation and reduction of nitrogen, parallel to the water splitting (reduction) to hydrogen. It is apparent from Tafel plots and impedance measurements that mechanism and dynamics of nitrogen reduction depends on the applied electroreduction potential. The catalytic system exhibits certain tolerance with respect to the competitive hydrogen evolution and gives (during electrolysis at -0.4 V vs. RHE) the Faradaic efficiency, namely, the selectivity (molar) efficiency, toward production of NH3 on the level of 60%. Under such conditions, the NH3-yield rate has been found to be equal to 7.5 µmol cm−2 h−1 (21 µmol m−2 s−1). By referring to classic concepts of electrochemical kinetic analysis, the rate constant in heterogeneous units has been found to be on the moderate level of 1-2*10−4 cm s−1 (at -0.4 V). The above mentioned iron-phosphorous active sites, which are generated on surfaces of Fe2P particles, have also been demonstrated to exhibit strong catalytic properties during reductions of other electrochemically inert reactants, such as oxygen, nitrites and nitrates.
Ključne besede: nitrogen reduction, alkaline medium, iron phosphide catalyst, ammonia, electrochemical determinations
Objavljeno v RUNG: 30.11.2023; Ogledov: 2086; Prenosov: 5
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4.
Efficient Iron Phosphide Catalyst as a Counter Electrode in Dye-Sensitized Solar Cells : article
Abdullah Yildiz, Takwa Chouki, Aycan Atli, Moussab Harb, Sammy W Verbruggen, Rajeshreddy Ninakanti, Saim Emin, 2021, izvirni znanstveni članek

Opis: Developing an efficient material as a counter electrode (CE) with excellent catalytic activity, intrinsic stability, and low cost is essential for the commercial application of dye-sensitized solar cells (DSSCs). Transition metal phosphides have been demonstrated as outstanding multifunctional catalysts in a broad range of energy conversion technologies. Here, we exploited different phases of iron phosphide as CEs in DSSCs with an I–/I3–-based electrolyte. Solvothermal synthesis using a triphenylphosphine precursor as a phosphorus source allows to grow a Fe2P phase at 300 °C and a FeP phase at 350 °C. The obtained iron phosphide catalysts were coated on fluorine-doped tin oxide substrates and heat-treated at 450 °C under an inert gas atmosphere. The solar-to-current conversion efficiency of the solar cells assembled with the Fe2P material reached 3.96 ± 0.06%, which is comparable to the device assembled with a platinum (Pt) CE. DFT calculations support the experimental observations and explain the fundamental origin behind the improved performance of Fe2P compared to FeP. These results indicate that the Fe2P catalyst exhibits excellent performance along with desired stability to be deployed as an efficient Pt-free alternative in DSSCs.
Ključne besede: Iron phosphide, catalyst, counter electrode, dye-sensitized solar cell, solvothermal synthesis
Objavljeno v RUNG: 06.02.2023; Ogledov: 2234; Prenosov: 0
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