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Opis: A Pt nanoparticle catalyst supported on partially-defective CeO₂ was developed for sensitive voltammetric detection of ammonia (NH₃) in alkaline media (0.5 mol dm⁻³ NaOH), achieving a detection limit of 2–3 μmol dm⁻³. This system enables in situ NH₃ monitoring during nitrogen electroreduction at an Fe₃P catalyst, without medium transfer, minimizing contamination. The Pt-based electrode also serves as a diagnostic tool to confirm electrolyte and gas purity. Selective NH₃ formation with negligible hydrazine or hydroxylamine by-products was confirmed via voltammetry and spectrophotometry.
Ključne besede: electrochemical analysis, ammonia determination, alkaline medium, nitrogen electroreduction, iron phosphide, electroanalytical control experiments, ceria, platinum nanoparticles, rhodium nanoparticles
Objavljeno v RUNG: 21.05.2025; Ogledov: 117; Prenosov: 0
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Opis: Widespread application of organic-inorganic halide perovskites (OIHP) still faces a major obstacle in mitigating moisture-induced degradation. Integrating organic spacers, as defect passivation facilitators along with low-dimensional phase (LDP) formation is an effective approach to enhance the efficiency and robustness of 3D methyl ammonium lead iodide (MAPI) in photovoltaics (PV). Here, the formamidinium cation (FA+) employing 3,5-difluorobenzene-1-carboximidamidium iodide (2F), 4-(trifluoromethyl)benzene-1-carboximidamidium iodide (3F), and 2,3,4,5,6-pentafluorobenzene-1-carboximidamidium iodide (5F) organic spacers as passivation layer in 3D/LDP OIHP solar cells is utilized. Fluorine atom position and quantity in organic spacers change the optoelectronic characteristics of the perovskites, enhancing hydrophobicity, facilitating LDP formation, and augmenting dipole moments, thereby facilitating charge separation processes. PV performance analysis reveals that 3F-treated 3D/LDP devices achieve the highest efficiency of 19.22%. Experimental results and density functional theory (DFT) studies attribute the higher performance of 3F-modified devices to effective LDP formation, enhanced passivation of defect states at perovskite surfaces and grain boundaries, the highest dipole moment and lowest band gap among the evaluated spacers. The stability tests show that, after 1000 h, 3F- and 5F-modified 3D/LDP OIHP devices retain over 85% of their initial efficiency. This research opens novel avenues for designing appropriate organic spacers to attenuate defects in 3D/LDP PV devices.
Ključne besede: fluorine-functionalized molecules, MAPI perovskite solar cells, deffect passivation
Objavljeno v RUNG: 20.02.2025; Ogledov: 719; Prenosov: 4
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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: 683; Prenosov: 2
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Opis: The waste electrical and electronic equipment (WEEE) is an important secondary source for renewable extraction of valuable metals and raw materials. The mineral biotechnologies are promising alternative to the current industrial chemical technologies for waste treatment, which are often accompanied with negative environmental impact. Here we report a systematic biotechnological strategy for recycling, recovering and extraction of metals from WEEE as biogenic formed nanoparticles. The process is based on two general steps – bioleaching (through autotrophic/heterotrophic bacteria), and extraction from the effluent as biosynthesised nanoscale materials. The obtained analytical data revealed that copper was bioleached in the form of nanoparticles, the efficiency being more than 90 %, which was the highest achieved value in comparison with the other metals. The recovered content of gold was less than 50 %, but the efforts for improvement of microbial leaching efficiency of Au are still in progress. The reported eco–friendly biotechnological approach enables proper implementation of new resource recovery–oriented recycling strategies with reduced risk of negative impact on nature.
Ključne besede: biotechnological recycling, secondary raw materials, nanoparticles
Objavljeno v RUNG: 10.01.2025; Ogledov: 593; Prenosov: 4
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Ključne besede: electrocatalytic properties, iron phosphides
Objavljeno v RUNG: 08.01.2025; Ogledov: 593; Prenosov: 0
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