Research

15 pages, 3809 KiB

Open AccessArticle

Enhancement of Polyacrylic Acid/Silicon Carbide Nanocomposites’ Optical Properties for Potential Application in Renewable Energy

by Farhan Lafta Rashid, Ahmed Hashim, Anmar Dulaimi, Aseel Hadi, Hamed Ibrahim, Mudhar A. Al-Obaidi and Arman Ameen

J. Compos. Sci. 2024, 8(4), 123; https://doi.org/10.3390/jcs8040123 - 28 Mar 2024

Viewed by 532

Abstract

Composites made from polymers and nanoparticles have promise to be effective solar collectors and thermal energy storage devices due to benefits including improved thermal characteristics and increased structural stability. This study intends to fabricate polyacrylic acid/silicon carbide (PAA−SiC) nanocomposites and examine the optical [...] Read more.

Composites made from polymers and nanoparticles have promise to be effective solar collectors and thermal energy storage devices due to benefits including improved thermal characteristics and increased structural stability. This study intends to fabricate polyacrylic acid/silicon carbide (PAA−SiC) nanocomposites and examine the optical properties for use in solar collectors and thermal energy storage (TES) fields. The optical properties of PAA−SiC nanocomposites are investigated within the wavelength between 340 and 840 nm. The findings indicate that an increase in SiC concentration in the PAA aqueous solution to 50 g/L at a wavelength of λ = 400 nm causes an increase in the absorption by 50.2% besides a reduction in transmission by 6%. Furthermore, the energy band gaps were reduced from 3.25 eV to 2.95 eV to allow for the transition, and subsequently reduced from 3.15 eV to 2.9 eV to allow for forbidden transition as a result of the increasing SiC concentration from 12.5 g/L to 50 g/L. The optical factors of energy absorption and optical conductivity were also enhanced with a rising SiC concentration from 12.5 to 50 g/L. Specifically, an improvement of 61% in the melting time of PAA−SiC−H₂O nanofluids is concluded. Accordingly, it can be said that the PAA−SiC−H₂O nanofluids are suitable for renewable energy and TES systems. Full article

(This article belongs to the Special Issue Nanocomposite Materials for Energy, Environment and Sustainable Development)

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16 pages, 3653 KiB

Open AccessArticle

Photocatalytic Decomposition of Rhodamine B and Selective Oxidation of 5-Hydroxymethylfurfural by β-Bi₂O₃/Bi₁₂SiO₂₀ Nanocomposites Produced by Laser

by Aleksandra G. Golubovskaya, Tamara S. Kharlamova, Ekaterina A. Gavrilenko, Elena D. Fakhrutdinova, Olga V. Vodyankina, Sergei A. Kulinich and Valery A. Svetlichnyi

J. Compos. Sci. 2024, 8(2), 42; https://doi.org/10.3390/jcs8020042 - 24 Jan 2024

Viewed by 1226

Abstract

In this work, we studied the catalytic performance of a β-Bi₂O₃/Bi₁₂SiO₂₀ nanocomposite material in the reactions involving the photodecomposition of rhodamine B and selective photooxidation of 5-hydroxymethylfurfural (HMF). The semiconductor composite nanomaterial was obtained by means [...] Read more.

In this work, we studied the catalytic performance of a β-Bi₂O₃/Bi₁₂SiO₂₀ nanocomposite material in the reactions involving the photodecomposition of rhodamine B and selective photooxidation of 5-hydroxymethylfurfural (HMF). The semiconductor composite nanomaterial was obtained by means of the mechanical grinding of a mixture of nanopowders of β-Bi₂O₃ and sillenite, both individually produced via pulsed laser ablation. The crystal structure of the prepared composite particles was confirmed by means of X-ray diffraction, while the optical properties of both individual components and their composite (with different ratios of Bi₂O₃ and Bi₁₂SiO₂₀) were also studied. The photocatalytic activity of the composite particles was studied in the course of their decomposition of rhodamine B under LED excitation at wavelengths of 375, 410 and 470 nm. It was shown that the optimal β-Bi₂O₃/Bi₁₂SiO₂₀ ratio in the composite particles resulted in their photocatalytic activity exceeding those of both single-phase β-Bi₂O₃ and Bi₁₂SiO₂₀, as well as that of their mixtures (by ~2.3 times for the excitation of an LED with λ = 375 nm). The novel composite particles were also found to perform better in the selective photocatalytic oxidation of HMF: at a conversion of ~5%, the selectivity toward DFF of the nanocomposite was significantly higher (10.3%) than that of sample Bi₂O₃ (−4.2%). A model was proposed that explains the increase in activity of the newly prepared photocatalyst due to the formation of a type II heterojunction in its particles. Full article

(This article belongs to the Special Issue Nanocomposite Materials for Energy, Environment and Sustainable Development)

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14 pages, 6088 KiB

Open AccessArticle

Glass-Containing Matrices Based on Borosilicate Glasses for the Immobilization of Radioactive Wastes

by Olga N. Koroleva, Lyubov A. Nevolina and Nadezhda M. Korobatova

J. Compos. Sci. 2023, 7(12), 505; https://doi.org/10.3390/jcs7120505 - 04 Dec 2023

Viewed by 1182

Abstract

Glass-containing materials are widely considered among the most reliable materials for the immobilization of radioactive waste materials. The present work considers the synthesis of glass–ceramic and glass crystalline composite materials based on borosilicate glasses. The synthesis of glass–ceramic materials was carried out by [...] Read more.

Glass-containing materials are widely considered among the most reliable materials for the immobilization of radioactive waste materials. The present work considers the synthesis of glass–ceramic and glass crystalline composite materials based on borosilicate glasses. The synthesis of glass–ceramic materials was carried out by a gradual temperature decrease, followed by crystallization for several hours. Sintering of crushed samples with crystalline components was carried out as an alternative procedure. Porous glasses were produced from glass melts by quenching. After impregnating the resulting porous materials with aqueous solutions of cesium nitrate, compaction of the glass was carried out to form glass crystalline composites. The thermochemical characteristics of the parent glasses were determined using the differential scanning calorimetry method. The phase composition and structure of the glass-containing materials were determined using X-ray phase analysis, X-ray spectral microanalysis, and Raman spectroscopy. Full article

(This article belongs to the Special Issue Nanocomposite Materials for Energy, Environment and Sustainable Development)

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11 pages, 2307 KiB

Open AccessArticle

Sulfur-Doped Nickel–Iron LDH@Cu Core–Shell Nanoarrays on Copper Mesh as High-Performance Electrocatalysts for Oxygen Evolution Reaction

by Zhichao Zhang, Jiahao Guo, Yuhan Sun, Qianwei Wang, Mengyang Li, Feng Cao and Shuang Han

J. Compos. Sci. 2023, 7(12), 486; https://doi.org/10.3390/jcs7120486 - 23 Nov 2023

Viewed by 1172

Abstract

The oxygen evolution reaction (OER) is a slow step in electrocatalytic water splitting. NiFe layered double hydroxides (LDH) have shown promise as affordable OER electrocatalysts, but their performance is hindered by poor charge transfer and sluggish kinetics. To address this, we doped NiFe [...] Read more.

The oxygen evolution reaction (OER) is a slow step in electrocatalytic water splitting. NiFe layered double hydroxides (LDH) have shown promise as affordable OER electrocatalysts, but their performance is hindered by poor charge transfer and sluggish kinetics. To address this, we doped NiFe LDH with sulfur (S) using an in situ electrodeposition method. By growing S-doped NiFe LDH on Cu nanoarrays, we created core–shell structures that improved both the thermodynamics and kinetics of OER. The resulting S-NiFe LDH@Cu core–shell nanoarrays exhibited enhanced activity in water oxidation, with a low potential of 236 mV (at 50 mA cm⁻²) and a small Tafel slope of 50.64 mV dec⁻¹. Moreover, our alkaline electrolyzer, based on these materials, demonstrated remarkable activity, with a low voltage of 1.56 V at 100 mA cm⁻² and excellent durability. The core–shell nanoarray structures provided a larger electroactive surface area, facilitated fast electron transport, and allowed for effective gas release. These findings highlight the potential of S-NiFe LDH@Cu core–shell nanoarrays as efficient OER electrocatalysts. Full article

(This article belongs to the Special Issue Nanocomposite Materials for Energy, Environment and Sustainable Development)

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12 pages, 2519 KiB

Open AccessArticle

Preparation and Properties of Flexible CuI/Polyvinylpyrrolidone Nanocomposite Thermoelectric Film

by Xiaowen Han, Xinru Zuo, Ying Liu, Zixing Wang and Kefeng Cai

J. Compos. Sci. 2023, 7(11), 461; https://doi.org/10.3390/jcs7110461 - 03 Nov 2023

Viewed by 1229

Abstract

A facile preparation method for flexible p-type CuI/polyvinylpyrrolidone (PVP) nanocomposite thermoelectric (TE) film is developed. First, CuI powder was synthesized by a one-pot method; second, PVP was coated in situ with the CuI powder; third, the CuI/PVP nanocomposite film was prepared on a [...] Read more.

A facile preparation method for flexible p-type CuI/polyvinylpyrrolidone (PVP) nanocomposite thermoelectric (TE) film is developed. First, CuI powder was synthesized by a one-pot method; second, PVP was coated in situ with the CuI powder; third, the CuI/PVP nanocomposite film was prepared on a nylon membrane by vacuum filtration and then hot-pressing. Transmission electron microscopy (TEM) observation indicates that the film consists of CuI nanograins with an average size of ~15 nm and PVP distributed at the inner wall of nanopores and the surface of the CuI nanograins. The composite film shows a large Seebeck coefficient of ~605 µVK⁻¹ and a power factor of ~8.05 µWm⁻¹K⁻² at 300 K. The nanocomposite film also exhibits excellent flexibility (~96% of initial electrical conductivity retention after being bent 1000 times along a 4 mm radius rod). A single-leg TE module outputs a voltage of ~3.6 mV when the temperature difference is 6 K. This work provides a fast, simple, and environmentally friendly method by which to prepare flexible CuI/PVP nanocomposite TE film with a large Seebeck coefficient, which could be used as a wearable sensor. Full article

(This article belongs to the Special Issue Nanocomposite Materials for Energy, Environment and Sustainable Development)

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16 pages, 3484 KiB

Open AccessArticle

Mesoporous Layered Double Hydroxides: Synthesis for High Effective Uranium Ions Sorption from Seawater and Salt Solutions on Nanocomposite Functional Materials

by Valeria A. Balybina, Artur N. Dran’kov, Oleg O. Shichalin, Natalia Yu. Savel’eva, Nadezhda G. Kokorina, Zhanna C. Kuular, Nikita P. Ivanov, Svetlana G. Krasitskaya, Andrei I. Ivanets and Evgeniy K. Papynov

J. Compos. Sci. 2023, 7(11), 458; https://doi.org/10.3390/jcs7110458 - 03 Nov 2023

Cited by 2 | Viewed by 1180

Abstract

A series of sorption materials based on layered double hydroxides (Co-Fe LDH, Ni-Fe LDH, and Zn-Ti LDH) were obtained by a facile and environmentally friendly method of coprecipitation. A low particle size of no more than 10 µm was achieved. The use of [...] Read more.

A series of sorption materials based on layered double hydroxides (Co-Fe LDH, Ni-Fe LDH, and Zn-Ti LDH) were obtained by a facile and environmentally friendly method of coprecipitation. A low particle size of no more than 10 µm was achieved. The use of transition metals makes it possible to obtain compounds that are mechanically and chemically stable in aggressive environments. XRD analysis revealed that the compounds have a highly organized crystalline structure. Using SEM, it was determined that Co-Fe LDH and Ni-Fe LDH had a loose, highly dispersed surface structure, while Zn-Ti LDH had a monolithic surface structure. U(VI) adsorption on the obtained materials in solutions containing Na₂CO₃, Na₂SO₄, KNO₃, NaCl, K₃PO₄, and NaHCO_3, was studied in batch mode. The degree of purification in the presence of these salts reached 99.9%, while the distribution coefficient K_d reached 10⁵ mL/g. Sorption capacity q_max and equilibrium adsorption constants K_f and K_L for U(VI) adsorption in batch mode (for 24 h) from distilled and seawater were determined using the Freundlich and Langmuir equations. The highest sorption capacity of 101.6 mg/g in seawater and 114.1 mg/g in distilled water was registered for Co-Fe-LDH. The presence of competing ions in seawater can reduce sorption efficiency by up to 40%. The provided research allowed us to conclude that the obtained materials, Co-Fe LDH, Ni-Fe LDH, and Zn-Ti LDH are promising for the sorption removal of U(VI) from aqueous media of medium salinity. Full article

(This article belongs to the Special Issue Nanocomposite Materials for Energy, Environment and Sustainable Development)

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13 pages, 5100 KiB

Open AccessArticle

Synthesis and Properties of Rubidium Salts of Phosphotungstic Acid

by Andrey A. Belmesov, Alexander A. Glukhov, Maxim V. Tsvetkov, Lyubov V. Shmygleva, Timofey A. Shikhov, Aleksey O. Lembikov, Anton A. Belov, Nikita P. Ivanov and Oleg O. Shichalin

J. Compos. Sci. 2023, 7(11), 454; https://doi.org/10.3390/jcs7110454 - 01 Nov 2023

Viewed by 1379

Abstract

The work is devoted to the study of the influence of synthesis conditions on the properties of water-insoluble rubidium salts of phosphotungstic acid (PTA). Such heteropoly compounds have a wide range of applications, including in the field of electrocatalysts and solid electrolytes for [...] Read more.

The work is devoted to the study of the influence of synthesis conditions on the properties of water-insoluble rubidium salts of phosphotungstic acid (PTA). Such heteropoly compounds have a wide range of applications, including in the field of electrocatalysts and solid electrolytes for various electrochemical devices. The acid salts of PTA with high activity of acid sites on the particle surface are of particular interest. It is known that the properties of water-insoluble PTA salts strongly depend on synthesis conditions, such as the ratio of reagents, temperature, concentrations, and other parameters. The work examines the influence of the ratio and concentration of reagents on the sizes of crystallites and agglomerates, specific surface area (SSA), porosity, water content, and ionic conductivity of the synthesized PTA salts. The SSA value of the obtained samples varied in the range of 84–123 m² g⁻¹, and the ionic conductivity was 13–90 mS cm⁻¹ at room temperature and 75% RH. An increase in the acid concentration and the degree of proton substitution led to an increase in SSA, accompanied by an increase in particle sizes without changing the size of crystallites. The results of the work may be useful for the development of new materials based on the obtained salts in many fields, including hydrogen energy. Full article

(This article belongs to the Special Issue Nanocomposite Materials for Energy, Environment and Sustainable Development)

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16 pages, 4726 KiB

Open AccessArticle

Thermoelectric and Magnetic Properties and Electronic Structure of Solid Solutions CuCr_1-xLa_xS₂

by Evgeniy V. Korotaev, Mikhail M. Syrokvashin and Irina Yu. Filatova

J. Compos. Sci. 2023, 7(10), 436; https://doi.org/10.3390/jcs7100436 - 13 Oct 2023

Viewed by 896

Abstract

The oxidation states of atoms in CuCr_1-xLa_xS₂ (x = 0–0.03) solid solutions were determined using the analysis of Cu2p, Cr2p, S2p, and La3d core level binding energy. The cationic substitution did not significantly affect the charge distribution on [...] Read more.

The oxidation states of atoms in CuCr_1-xLa_xS₂ (x = 0–0.03) solid solutions were determined using the analysis of Cu2p, Cr2p, S2p, and La3d core level binding energy. The cationic substitution did not significantly affect the charge distribution on matrix elements (Cu, Cr, and S). The oxidation states of the atoms were identified as S²⁻ for sulfur, Cu⁺ for copper, and Cr³⁺ for chromium. The cationic substitution in CuCr_1-xLa_xS₂ was found to occur via the isovalent principle. The cationic substitution of CuCrS₂ matrix with lanthanum ions led to the enhancement of the Seebeck coefficient comparing CuCr_1-xLa_xS₂ to the initial matrix. The observed enhancement was attributed to the reconstruction of the valence band electronic structure after the cationic substitution. The maximum Seebeck coefficient value of 412 μV/K was measured for CuCr_0.985La_0.015S₂ at 420 K. An increase in the lanthanum concentration to x = 0.03 caused a suppression of the Seebeck coefficient. The synthetic route was found to significantly affect both the magnetic properties and charge carrier concentration. The magnetic properties of CuCr_1-xLa_xS₂ synthesized using metal sulfide reagents cannot be interpreted using the simple isovalent Cr³⁺ to La³⁺ cationic substitution model. The defectiveness of the samples and the formation of the impurity CuLaS₂ phase could be additional factors that affect the magnetic properties of CuCr_1-xLa_xS₂. Full article

(This article belongs to the Special Issue Nanocomposite Materials for Energy, Environment and Sustainable Development)

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20 pages, 20009 KiB

Open AccessArticle

Study on the Impact of a Combination of Synthetic Wollastonite and 2-Mercaptobenzothiazole-Based Fillers on UHMWPE Polymeric Matrix

by Sakhayana N. Danilova, Aitalina A. Okhlopkova, Sofia B. Yarusova, Afanasy A. Dyakonov, Pavel S. Gordienko, Evgeniy K. Papynov, Oleg O. Shichalin, Igor Yu. Buravlev, Andrey P. Vasilev, Ivan G. Zhevtun and Natalya V. Ivanenko

J. Compos. Sci. 2023, 7(10), 431; https://doi.org/10.3390/jcs7100431 - 13 Oct 2023

Viewed by 1681

Abstract

This study investigates the impact of a binary filler on the physicomechanical and tribological properties, as well as structure, of polymeric composite materials based on ultra-high-molecular-weight polyethylene. The organic modifier—2-mercaptobenzothiazole and wollastonite particles synthesized from two different systems (modeled and derived from waste) [...] Read more.

This study investigates the impact of a binary filler on the physicomechanical and tribological properties, as well as structure, of polymeric composite materials based on ultra-high-molecular-weight polyethylene. The organic modifier—2-mercaptobenzothiazole and wollastonite particles synthesized from two different systems (modeled and derived from waste) were used as the binary filler. The synthesis of wollastonite was carried out in the complex model system (CaSO₄·2H₂O–SiO₂·nH₂O–KOH–H₂O) and from technogenic waste (borogypsum). It was demonstrated that the introduction of the binary filler made it possible to obtain an optimal combination of mechanical and tribological properties. It was found that during the wear of polymeric composite materials loaded with organic fillers, the fillers migrate to the friction surface, providing a shield against abrasive wear of the steel counterface. Due to the modification of ultra-high-molecular-weight polyethylene by 2-mercaptobenzothiazole, the interdiffusion of polymeric matrix macromolecules and interphase coupling with wollastonite particles improve. The 2-mercaptobenzothiazole organic compound used as the filler facilitates the relaxation processes within the composite under external loads. Full article

(This article belongs to the Special Issue Nanocomposite Materials for Energy, Environment and Sustainable Development)

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14 pages, 3337 KiB

Open AccessArticle

Hybrid Sol–Gel and Spark Plasma Sintering to Produce Perovskite-like SrTiO₃ Ceramics for Radioactive Waste Isolation

by Anton A. Belov, Oleg O. Shichalin, Evgeniy K. Papynov, Igor Yu. Buravlev, Erhan S. Kolodeznikov, Olesya V. Kapustina, Semen A. Azon, Nikolay B. Kondrikov, Alexander N. Fedorets and Ivan G. Tananaev

J. Compos. Sci. 2023, 7(10), 421; https://doi.org/10.3390/jcs7100421 - 09 Oct 2023

Viewed by 1256

Abstract

The paper presents a reliable technology combining sol–gel synthesis and spark plasma sintering (SPS) to obtain SrTiO₃ perovskite-type ceramics with excellent physicomechanical properties and hydrolytic stability for the long-term retention of radioactive strontium radionuclides. The Pechini sol–gel method was used to synthesize [...] Read more.

The paper presents a reliable technology combining sol–gel synthesis and spark plasma sintering (SPS) to obtain SrTiO₃ perovskite-type ceramics with excellent physicomechanical properties and hydrolytic stability for the long-term retention of radioactive strontium radionuclides. The Pechini sol–gel method was used to synthesize SrTiO₃ powder from Sr(NO₃)₂ and TiCl₃ (15%) precursors. Ceramic matrix samples were fabricated by SPS in the temperature range of 900–1200 °C. The perovskite structure of the synthesized initial SrTiO₃ powder was confirmed by X-ray diffraction and thermal analysis results. Scanning electron microscopy revealed agglomeration of the nanoparticles and a pronounced tendency for densification in the sintered compact with increasing sintering temperature. Chemical homogeneity of ceramics was confirmed by energy dispersive X-ray analysis. Physicochemical characteristic studies included density measurement results (3.11–4.80 g·cm⁻³), dilatometric dependencies, Vickers microhardness (20–900 HV), and hydrolytic stability (10⁻⁶–10⁻⁷ g·cm⁻²·day⁻²), exceeding GOST R 50926-96 and ISO 6961:1982 requirements for solid-state matrices. Ceramic sintered at 1200 °C demonstrated the lowest strontium leaching rate of 10⁻⁷ g/cm²·day, optimal for radioactive waste (RAW) isolation. The proposed approach can be used to fabricate mineral-like forms suitable for RAW handling. Full article

(This article belongs to the Special Issue Nanocomposite Materials for Energy, Environment and Sustainable Development)

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21 pages, 11499 KiB

Open AccessArticle

Al₂O₃-Phosphate Bioceramic Fabrication via Spark Plasma Sintering-Reactive Synthesis: In Vivo and Microbiological Investigation

by Evgeniy Papynov, Oleg Shichalin, Vladimir Apanasevich, Nataliya Plekhova, Anton Belov, Igor Buravlev, Arseny Portnyagin, Vitaliy Mayorov, Yuliya Skurikhina, Alexander Fedorets, Anastasiya Buravleva, Ekaterina Gridasova and Yun Shi

J. Compos. Sci. 2023, 7(10), 409; https://doi.org/10.3390/jcs7100409 - 03 Oct 2023

Viewed by 1110

Abstract

This research introduces a method to enhance the biocompatibility of bioinert Al₂O₃-based ceramics by incorporating calcium phosphates (hydroxyapatite (HAp) and tricalcium phosphate (TCP)) into alumina via spark plasma sintering-reactive sintering (SPS-RS). TGA/DTG/DTA and XRD revealed phase formation of HAp [...] Read more.

This research introduces a method to enhance the biocompatibility of bioinert Al₂O₃-based ceramics by incorporating calcium phosphates (hydroxyapatite (HAp) and tricalcium phosphate (TCP)) into alumina via spark plasma sintering-reactive sintering (SPS-RS). TGA/DTG/DTA and XRD revealed phase formation of HAp and TCP and determined the main temperature points of solid-phase reactions occurring in situ during the sintering of the CaO-CaHPO₄ mixture within the volume of Al₂O₃ under SPS-RS conditions in the range of 900–1200 °C. SEM, EDX, low temperature, and nitrogen physisorption were used to monitor changes in the morphology, structure, and elemental composition of bioceramics. Structural meso- and macroporosity, with a mean mesopore size of 10 nm, were revealed in the ceramic volume, while sintering temperature was shown to play a destructive role towards the porous inorganic framework. The physico-chemical characterization demonstrated increased relative density (up to 95.1%), compressive strength (640 MPa and above), and Vickers microhardness (up to 700 HV) depending on the HAp and TCP content and sintering temperature. Four bioceramic samples with different contents of HAP (20 and 50 wt.%) were bio-tested in in vivo models. The samples were implanted into the soft tissues under the superficial fascia of the thorax of a laboratory animal (a New Zealand White rabbit, female) in the area of the trapezius muscle and the broadest muscle of the back. Based on the results of the assessment of the surrounding tissue reaction, the absence of specific inflammation, necrosis, and tumor formation in the tissues during the implantation period of 90 days was proven. Microbial tests and dynamics of Pseudomonas aeruginosa bacterial film formation on bioceramic surfaces were studied with respect to HAp content (20 and 50 wt.%) and holding time (18, 24, and 48 h) in the feed medium. Full article

(This article belongs to the Special Issue Nanocomposite Materials for Energy, Environment and Sustainable Development)

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19 pages, 5271 KiB

Open AccessArticle

Enhancing Photocatalytic Pollutant Degradation through S-Scheme Electron Transfer and Sulfur Vacancies in BiFeO₃/ZnIn₂S₄ Heterojunctions

by Ge-Ge Zheng, Xin Lin, Zhen-Xing Wen, Yu-Hao Ding, Rui-Hui Yun, Gaurav Sharma, Amit Kumar and Florian J. Stadler

J. Compos. Sci. 2023, 7(7), 280; https://doi.org/10.3390/jcs7070280 - 07 Jul 2023

Cited by 3 | Viewed by 959

Abstract

Photocatalytic degradation plays a crucial role in wastewater treatment, and the key to achieving high efficiency is to develop photocatalytic systems that possess excellent light absorption, carrier separation efficiency, and surface-active sites. Among various photocatalytic systems, S-type heterojunctions have shown remarkable potential for [...] Read more.

Photocatalytic degradation plays a crucial role in wastewater treatment, and the key to achieving high efficiency is to develop photocatalytic systems that possess excellent light absorption, carrier separation efficiency, and surface-active sites. Among various photocatalytic systems, S-type heterojunctions have shown remarkable potential for efficient degradation. This work delves into the construction of S-type heterojunctions of ternary indium metal sulfide and bismuth ferrite nanofibers with the introduction of sulfur vacancy defects and morphology modifications to enhance the photocatalytic degradation performance. Through the impregnation method, BiFeO₃/ZnIn₂S₄ heterojunction materials were synthesized and optimized. The 30% BiFeO₃/ZnIn₂S₄ heterojunction exhibited superior photocatalytic performance with higher sulfur vacancy concentration than ZnIn₂S₄. The in-situ XPS results demonstrate that the electrons between ZnIn₂S₄ and BFO are transferred via the S-Scheme, and after modification, ZnIn₂S₄ has a more favorable surface morphology for electron transport, and its flower-like structure interacts with the nanofibers of BFO, which has a further enhancement of the reaction efficiency for degrading pollutants. This exceptional material demonstrated a remarkable 99% degradation of Evans blue within 45 min and a significant 68% degradation of ciprofloxacin within 90 min. This work provides a feasible idea for developing photocatalysts to deal with the problem of polluted water resources under practical conditions. Full article

(This article belongs to the Special Issue Nanocomposite Materials for Energy, Environment and Sustainable Development)

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20 pages, 5745 KiB

Open AccessArticle

Ternary Ni-Ce-Mg-O Composites: In-Depth Optical Spectroscopy Study and Catalytic Performance in CO Oxidation

by Grigory B. Veselov, Vladimir O. Stoyanovskii and Aleksey A. Vedyagin

J. Compos. Sci. 2023, 7(6), 251; https://doi.org/10.3390/jcs7060251 - 15 Jun 2023

Cited by 2 | Viewed by 934

Abstract

In the present work, ternary Ni-Ce-Mg-O composites containing various amounts of NiO and CeO₂ were synthesized via a sol-gel approach. Aqueous solutions of cerium and nickel nitrates were introduced at the stage of hydrolysis of magnesium methoxide, which allowed for avoiding the [...] Read more.

In the present work, ternary Ni-Ce-Mg-O composites containing various amounts of NiO and CeO₂ were synthesized via a sol-gel approach. Aqueous solutions of cerium and nickel nitrates were introduced at the stage of hydrolysis of magnesium methoxide, which allowed for avoiding the use of expensive organic precursors. It was revealed that the properties of the composites were defined by the complex interactions between NiO, CeO₂, and MgO components. In order to perform an in-depth characterization of the prepared samples, diffuse reflectance UV–vis and Raman spectroscopies were applied. According to the results of these methods, Mg²⁺ ions did not substitute Ce⁴⁺ ions in the CeO₂ lattice. However, in the case of the Ni-containing samples, approximately 2–3% of the Ce⁴⁺ ions were substituted by Ni²⁺, thus resulting in the formation of vacancies in the CeO₂. The strong interaction of NiO with MgO predictably resulted in the formation of Ni_xMg_1−xO solid solutions. When the NiO content in the sample was 20 wt%, the composition of the formed solid solution was estimated to be Ni_0.60Mg_0.40O. In addition, the presence of CeO₂ affected the texture of the ternary composites, thus leading to a slight decrease in the specific surface area. The catalytic performance of the Ni-Ce-Mg-O composites was examined in the CO oxidation reaction under prompt thermal aging conditions. The choice of reaction conditions was due to a high sensitivity of the CO oxidation response toward the available metal surface area and possible metal-support interactions. Full article

(This article belongs to the Special Issue Nanocomposite Materials for Energy, Environment and Sustainable Development)

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18 pages, 5100 KiB

Open AccessArticle

Synthesis of Ni-Cu-CNF Composite Materials via Carbon Erosion of Ni-Cu Bulk Alloys Prepared by Mechanochemical Alloying

by Sofya D. Afonnikova, Grigory B. Veselov, Yury I. Bauman, Evgeny Y. Gerasimov, Yury V. Shubin, Ilya V. Mishakov and Aleksey A. Vedyagin

J. Compos. Sci. 2023, 7(6), 238; https://doi.org/10.3390/jcs7060238 - 06 Jun 2023

Cited by 5 | Viewed by 1203

Abstract

The unique physical and chemical properties of composite materials based on carbon nanofibers (CNFs) makes them attractive to scientists and manufacturers. One promising method to produce CNFs is catalytic chemical vapor deposition (CCVD). In the present work, a method based on carbon erosion [...] Read more.

The unique physical and chemical properties of composite materials based on carbon nanofibers (CNFs) makes them attractive to scientists and manufacturers. One promising method to produce CNFs is catalytic chemical vapor deposition (CCVD). In the present work, a method based on carbon erosion (CE) of bulk microdispersed Ni-Cu alloys has been proposed to prepare efficient catalysts for the synthesis of CNF-based composites. The initial Ni-Cu alloys were obtained by mechanochemical alloying (MCA) of metallic powders in a planetary mill. The effect of MCA duration on the phase composition of Ni-Cu samples was studied by X-ray diffraction analysis and temperature-programmed reduction in hydrogen. It has been also revealed that, during such stages as heating, reduction, and short-term exposure to the reaction mixture (C₂H₄/H₂/Ar) at 550 °C, the formation of a Ni-based solid solution from the initial Ni-Cu alloys takes place. The early stages of the CE process were monitored by transmission electron microscopy combined with energy-dispersive X-Ray analysis. It was found that the composition of the catalytic particles is identical to that of the initial alloy. The morphological and structural features of the prepared Ni-Cu-CNF composites were studied by scanning and transmission electron microscopies. The textural characteristics of the composites were found to be dependent on the reaction time. Full article

(This article belongs to the Special Issue Nanocomposite Materials for Energy, Environment and Sustainable Development)

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