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1.
Phys Chem Chem Phys ; 26(15): 11271-11276, 2024 Apr 17.
Artículo en Inglés | MEDLINE | ID: mdl-38563160

RESUMEN

Materials with multiple principal elements (middle- and high-entropy materials), are used in emerging applications in various fields due to their unique properties, driven by configuration entropy. Improved understanding and experimental investigations of the impact of the entropy of mixing on the properties of these materials are of large practical interest. Here we show a simplified limited area calculation approach for assessing the entropy of mixing using a CoCuFeNi model nanoalloy. Based on our calculations we propose a new parametric entropy-based criterion, which defines critical scale parameter transition from the maximal entropy state to the entropy-depleted state of the system. The criterion could be used for generalized mechanistic assessment of the effect of the entropy of mixing on the characteristics of the materials with multiple principal elements and for the development and characterization of existing and new middle- and high-entropy materials with both simple single-, and more complex, multiple-sublattice structures.

2.
Environ Sci Pollut Res Int ; 30(9): 23363-23371, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-36323967

RESUMEN

Implementation of nanotechnology in agriculture is of interest primarily to improve the growth and productivity of crops, and to minimize the use of traditional expensive chemical fertilizers. This work presents a simple energy-conservative approach for the synthesis of CoCuFeNi high entropy alloy nanoparticles (HEA-NPs) capable of forming a stable suspension with a concentration of 0.3 g/L. The size, composition, and morphology of the nanoparticles were analyzed by XRD, SEM, TEM, and EDS. Obtained HEA-NPs were characterized by fine crystallinity with an average size of 25 nm. The investigated suspensions of HEA-NPs were tested for seeds germination and plants growth. The use of suspension of CoCuFeNi HEA-NPs for plant irrigating together with ordinary water showed positive results in plant biostimulation, which resulted in the plant height up to 12% for watercress and up to 50% for oil radish. CoCuFeNi HEA-NPs showed nice inactivation activity for Pseudomonas aeruginosa that was comparable for the use of Tetracycline.


Asunto(s)
Nanopartículas del Metal , Nanopartículas , Germinación , Aleaciones , Entropía , Semillas , Productos Agrícolas , Nanopartículas del Metal/química
3.
Materials (Basel) ; 15(15)2022 Jul 23.
Artículo en Inglés | MEDLINE | ID: mdl-35897563

RESUMEN

Active and stable catalysts are essential for effective hydrogenation of gaseous CO2 into valuable chemicals. This work focuses on the structural and catalytic features of single metals, i.e., Co and Ni, as well as bimetallic CoNi alloy catalysts synthesized via combustion of reactive sol-gels. Different characterization methods were used for studying the relationships between the structure, composition, and catalytic activity of the fabricated materials. All catalysts exhibited highly porous sponge-like microstructure. The outermost surfaces of the CoNi alloys were more saturated with Co, while a stoichiometric Co/Ni ratio was observed for the particle's bulk. Catalytic properties of the as-synthesized powders were studied in the CO2 hydrogenation reaction at 300 °C for over 80 h of time on stream. All the catalysts demonstrated exceptional selectivity with respect to CH4 formation. However, the combination of elemental Co and Ni in a single phase resulted in a synergistic effect in bulk alloy catalysts, with activity twofold to threefold that of single-metal catalysts. The activity and stability of the CoNi3 catalyst were higher than those previously reported for Ni-based catalysts. The reasons for this behavior are discussed.

4.
Inorg Chem ; 58(9): 5583-5592, 2019 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-30978012

RESUMEN

A single-step method for the preparation of metastable ε-Fe3N nanoparticles by combustion of reactive gels containing iron nitrate (Fe(NO3)3) and hexamethylenetetramine (C6H12N4) in an inert atmosphere is reported. The results of Fourier transform infrared spectroscopy (FTIR) and thermal analysis coupled with dynamic mass spectrometry revealed that the exothermic decomposition of a coordination complex formed between Fe(NO3)3 and HMTA is responsible for the formation of ε-Fe3N nanoscale particles with sizes of 5-15 nm. The magnetic properties between 5 and 350 K are characterized using a superconducting quantum interference device (SQUID) magnetometer, revealing a ferromagnetic behavior with a low-temperature magnetic moment of 1.09 µB/Fe, high room temperature saturation magnetization (∼80 emu/g), and low remanent magnetization (∼15 emu/g). The obtained value for the Curie temperature of ∼522 K is close to that (∼575 K) for bulk ε-Fe3N reported in the literature.

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