Editorial

2 pages, 196 KiB

Open AccessEditorial

Synthesis of Nanocomposites and Catalysis Applications

by Evgeny Gerasimov

Nanomaterials 2022, 12(5), 731; https://doi.org/10.3390/nano12050731 - 22 Feb 2022

Cited by 2 | Viewed by 1305

The term catalysis was introduced in the mid-19th century by the Swedish scientist Jöns Jakob Berzelius, ushering in the era of accelerated chemical reactions [...] Full article

(This article belongs to the Special Issue Synthesis of Nanocomposites and Catalysis Applications)

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19 pages, 5290 KiB

Open AccessFeature PaperArticle

One-Pot Thermal Synthesis of g-C₃N₄/ZnO Composites for the Degradation of 5-Fluoruracil Cytostatic Drug under UV-LED Irradiation

by Álvaro Pérez-Molina, Luisa M. Pastrana-Martínez, Lorena T. Pérez-Poyatos, Sergio Morales-Torres and Francisco J. Maldonado-Hódar

Nanomaterials 2022, 12(3), 340; https://doi.org/10.3390/nano12030340 - 21 Jan 2022

Cited by 13 | Viewed by 2250

Abstract

Graphitic carbon nitride (g-C₃N₄) was used to enhance the photocatalytic activity of ZnO nanoparticles for the degradation of 5-fluorouracil (5-FU) cytostatic drug under UV-LED irradiation. CN/ZnO composites were synthetized by an easy one-pot thermal method, varying the g-C₃ [...] Read more.

Graphitic carbon nitride (g-C₃N₄) was used to enhance the photocatalytic activity of ZnO nanoparticles for the degradation of 5-fluorouracil (5-FU) cytostatic drug under UV-LED irradiation. CN/ZnO composites were synthetized by an easy one-pot thermal method, varying the g-C₃N₄ loading, i.e., from 10 to 67 wt% and a post-thermal exfoliation in air. The physicochemical and optical properties of the materials were analyzed by several techniques. CN/ZnO composites showed a coral-like structure of spherical ZnO wurtzite particles on the g-C₃N₄ structure. In general, the synergism and heterojunction interface between both phases allowed the enhancement of the mesoporosity, light absorption ability, and the aromaticity of the corresponding composites. Moreover, the photocatalytic activity of the CN/ZnO composites was increased with the addition of g-C₃N₄ in comparison with pristine ZnO. The highest activity was found for the composite containing 25 wt% of g-C₃N₄ (i.e., CN25/ZnO), reaching the total degradation of 5-FU and a mineralization of 48% at 180 min, as well as a good photostability during four reuse cycles. Experiments with different pH solutions and scavengers allowed for the assessment of the reactive oxygen species (ROS) involved in the 5-FU degradation pathway, with radicals and non-radical species as the main responsible active species. Furthermore, a tentative photocatalytic mechanism was proposed for CN/ZnO composites. Full article

(This article belongs to the Special Issue Synthesis of Nanocomposites and Catalysis Applications)

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9 pages, 2035 KiB

Open AccessEditor’s ChoiceCommunication

Structural Insight into La_0.5Ca_0.5Mn_0.5Co_0.5O₃ Decomposition in the Methane Combustion Process

by Olga Nikolaeva, Aleksandr Kapishnikov and Evgeny Gerasimov

Nanomaterials 2021, 11(9), 2283; https://doi.org/10.3390/nano11092283 - 02 Sep 2021

Cited by 3 | Viewed by 1377

Abstract

Perovskite-like solid solution La_0.5Ca_0.5Mn_0.5Co_0.5O₃ was tested during the total methane combustion reaction. During the reaction, there is a noticeable decrease in methane conversion, the rate of catalyst deactivation increasing with an increase in temperature. [...] Read more.

Perovskite-like solid solution La_0.5Ca_0.5Mn_0.5Co_0.5O₃ was tested during the total methane combustion reaction. During the reaction, there is a noticeable decrease in methane conversion, the rate of catalyst deactivation increasing with an increase in temperature. The in situ XRD and HRTEM methods show that the observed deactivation occurs as a result of the segregation of calcite and cobalt oxide particles on the perovskite surface. According to the TGA, the observed drop in catalytic activity is also associated with a large loss of oxygen from the perovskite structure. Full article

(This article belongs to the Special Issue Synthesis of Nanocomposites and Catalysis Applications)

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15 pages, 4708 KiB

Open AccessArticle

Oxidative N-Formylation of Secondary Amines Catalyzed by Reusable Bimetallic AuPd–Fe₃O₄ Nanoparticles

by Sabyuk Yang, Ahra Cho, Jin Hee Cho and Byeong Moon Kim

Nanomaterials 2021, 11(8), 2101; https://doi.org/10.3390/nano11082101 - 18 Aug 2021

Cited by 8 | Viewed by 2637

Abstract

Bimetallic catalysts are gaining attention due to their characteristics of promoting reactivity and selectivity in catalyzed reactions. Herein, a new catalytic N-formylation of secondary amines using AuPd–Fe₃O₄ at room temperature is reported. Methanol was utilized as the formyl source [...] Read more.

Bimetallic catalysts are gaining attention due to their characteristics of promoting reactivity and selectivity in catalyzed reactions. Herein, a new catalytic N-formylation of secondary amines using AuPd–Fe₃O₄ at room temperature is reported. Methanol was utilized as the formyl source and 1.0 atm of O₂ gas served as an external oxidant. The bimetallic catalyst, consisting of Au and Pd, makes the reaction more efficient than that using each metal separately. In addition, the catalyst can be effectively recycled owing to the Fe₃O₄ support. Full article

(This article belongs to the Special Issue Synthesis of Nanocomposites and Catalysis Applications)

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20 pages, 23626 KiB

Open AccessFeature PaperArticle

Ni–Cu High-Loaded Sol–Gel Catalysts for Dehydrogenation of Liquid Organic Hydrides: Insights into Structural Features and Relationship with Catalytic Activity

by Yuliya Gulyaeva, Maria Alekseeva (Bykova), Olga Bulavchenko, Anna Kremneva, Andrey Saraev, Evgeny Gerasimov, Svetlana Selishcheva, Vasily Kaichev and Vadim Yakovlev

Nanomaterials 2021, 11(8), 2017; https://doi.org/10.3390/nano11082017 - 06 Aug 2021

Cited by 10 | Viewed by 2180

Abstract

The heightened interest in liquid organic hydrogen carriers encourages the development of catalysts suitable for multicycle use. To ensure high catalytic activity and selectivity, the structure–reactivity relationship must be extensively investigated. In this study, high-loaded Ni–Cu catalysts were considered for the dehydrogenation of [...] Read more.

The heightened interest in liquid organic hydrogen carriers encourages the development of catalysts suitable for multicycle use. To ensure high catalytic activity and selectivity, the structure–reactivity relationship must be extensively investigated. In this study, high-loaded Ni–Cu catalysts were considered for the dehydrogenation of methylcyclohexane. The highest conversion of 85% and toluene selectivity of 70% were achieved at 325 °C in a fixed-bed reactor using a catalyst with a Cu/Ni atomic ratio of 0.23. To shed light on the relationship between the structural features and catalytic performance, the catalysts were thoroughly studied using a wide range of advanced physicochemical tools. The activity and selectivity of the proposed catalysts are related to the uniformity of Cu distribution and its interaction with Ni via the formation of metallic solid solutions. The method of introduction of copper in the catalyst plays a crucial role in the effectiveness of the interaction between the two metals. Full article

(This article belongs to the Special Issue Synthesis of Nanocomposites and Catalysis Applications)

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19 pages, 3426 KiB

Open AccessArticle

The Formation of Mn-Ce Oxide Catalysts for CO Oxidation by Oxalate Route: The Role of Manganese Content

by Olga A. Bulavchenko, Tatyana N. Afonasenko, Alexey R. Osipov, Alena A. Pochtar’, Andrey A. Saraev, Zahar S. Vinokurov, Evgeny Yu. Gerasimov and Sergey V. Tsybulya

Nanomaterials 2021, 11(4), 988; https://doi.org/10.3390/nano11040988 - 12 Apr 2021

Cited by 6 | Viewed by 2220

Abstract

The Mn-Ce oxide catalysts active in the oxidation of CO were studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), transition electron microscopy (TEM), energy dispersive X-Ray (EDX), and a differential dissolution technique. The Mn-Ce catalysts were prepared by thermal [...] Read more.

The Mn-Ce oxide catalysts active in the oxidation of CO were studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), transition electron microscopy (TEM), energy dispersive X-Ray (EDX), and a differential dissolution technique. The Mn-Ce catalysts were prepared by thermal decomposition of oxalates by varying the Mn:Ce ratio. The nanocrystalline oxides with a fluorite structure and particle sizes of 4–6 nm were formed. The introduction of manganese led to a reduction of the oxide particle size, a decrease in the surface area, and the formation of a Mn_yCe_1−yO_2−δ solid solution. An increase in the manganese content resulted in the formation of manganese oxides such as Mn₂O₃, Mn₃O₄, and Mn₅O₈. The catalytic activity as a function of the manganese content had a volcano-like shape. The best catalytic performance was exhibited by the catalyst containing ca. 50 at.% Mn due to the high specific surface area, the formation of the solid solution, and the maximum content of the solid solution. Full article

(This article belongs to the Special Issue Synthesis of Nanocomposites and Catalysis Applications)

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16 pages, 5091 KiB

Open AccessArticle

Comparative Study of the Photocatalytic Hydrogen Evolution over Cd_1−xMn_xS and CdS-β-Mn₃O₄-MnOOH Photocatalysts under Visible Light

by Ksenia O. Potapenko, Anna Yu. Kurenkova, Andrey V. Bukhtiyarov, Evgeny Yu. Gerasimov, Svetlana V. Cherepanova and Ekaterina A. Kozlova

Nanomaterials 2021, 11(2), 355; https://doi.org/10.3390/nano11020355 - 01 Feb 2021

Cited by 7 | Viewed by 2546

Abstract

A series of solid solutions of cadmium and manganese sulfides, Cd_1−xMn_xS (x = 0–0.35), and composite photocatalysts, CdS-β-Mn₃O₄-MnOOH, were synthesized by precipitation with sodium sulfide from soluble cadmium and manganese salts with further hydrothermal treatment [...] Read more.

A series of solid solutions of cadmium and manganese sulfides, Cd_1−xMn_xS (x = 0–0.35), and composite photocatalysts, CdS-β-Mn₃O₄-MnOOH, were synthesized by precipitation with sodium sulfide from soluble cadmium and manganese salts with further hydrothermal treatment at 120 °C. The obtained photocatalysts were studied by the X-ray diffraction method (XRD), UV-vis diffuse reflectance spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and N₂ low temperature adsorption. The photocatalysts were tested in hydrogen production using a Na₂S/Na₂SO₃ aqueous solution under visible light (λ = 450 nm). It was shown for the first time that both kinds of photocatalysts possess high activity in hydrogen evolution under visible light. The solid solution Cd_0.65Mn_0.35S has an enhanced photocatalytic activity due to its valence and conduction band position tuning, whereas the CdS-β-Mn₃O₄-MnOOH (40–60 at% Mn) samples were active due to ternary heterojunction formation. Further, the composite CdS-β-Mn₃O₄-MnOOH photocatalyst had much higher stability in comparison to the Cd_0.65Mn_0.35S solid solution. The highest activity was 600 mmol g⁻¹ h⁻¹, and apparent quantum efficiency of 2.9% (λ = 450 nm) was possessed by the sample of CdS-β-Mn₃O₄-MnOOH (40 at% Mn). Full article

(This article belongs to the Special Issue Synthesis of Nanocomposites and Catalysis Applications)

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11 pages, 2461 KiB

Open AccessArticle

Preparation of Robust Hydrogen Evolution Reaction Electrocatalyst WC/C by Molten Salt

by Pengpeng Yan, Yuchen Wu, Xiaofeng Wei, Xuewei Zhu and Wei Su

Nanomaterials 2020, 10(9), 1621; https://doi.org/10.3390/nano10091621 - 19 Aug 2020

Cited by 9 | Viewed by 2386

Abstract

Tungsten carbide (WC) is an alternative to the costly and resource-constrained Pt-based catalysts for hydrogen evolution reaction (HER). In this work, a one-step facile and easily scalable approach is reported, to synthesize ultrafine WC by molten salt. Benefiting from the ideal synergistic catalytic [...] Read more.

Tungsten carbide (WC) is an alternative to the costly and resource-constrained Pt-based catalysts for hydrogen evolution reaction (HER). In this work, a one-step facile and easily scalable approach is reported, to synthesize ultrafine WC by molten salt. Benefiting from the ideal synergistic catalytic effect between the highly active WC nanoparticles and the conductive graphitic carbon, and strong charge transfer ability, the unique WC/C hybrids demonstrated excellent HER performance in both acid and alkaline medias with overpotentials of 112 and 122 mV, at a current density of 10 mA cm⁻² and Tafel slopes of 54.4 and 68.8 mV dec⁻¹, in acid and alkaline media, and remarkable stability. With the simplicity and low-cost of the synthetic approach, the strategy presented here can be extendable to the preparation of other transition metal-based/carbon hybrids for versatile applications. Full article

(This article belongs to the Special Issue Synthesis of Nanocomposites and Catalysis Applications)

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10 pages, 2807 KiB

Open AccessArticle

Ultrafine Pd Nanoparticles Supported on Soft Nitriding Porous Carbon for Hydrogen Production from Hydrolytic Dehydrogenation of Dimethyl Amine-Borane

by Zhaoyu Wen, Qiong Fu, Jie Wu and Guangyin Fan

Nanomaterials 2020, 10(8), 1612; https://doi.org/10.3390/nano10081612 - 17 Aug 2020

Cited by 22 | Viewed by 2750

Abstract

Simple and efficient synthesis of a nano-catalyst with an excellent catalytic property for hydrogen generation from hydrolysis of dimethyl amine-borane (DMAB) is a missing piece. Herein, effective and recycled palladium (Pd) nanoparticles (NPs) supported on soft nitriding porous carbon (NPC) are fabricated and [...] Read more.

Simple and efficient synthesis of a nano-catalyst with an excellent catalytic property for hydrogen generation from hydrolysis of dimethyl amine-borane (DMAB) is a missing piece. Herein, effective and recycled palladium (Pd) nanoparticles (NPs) supported on soft nitriding porous carbon (NPC) are fabricated and applied for DMAB hydrolysis. It is discovered that the soft nitriding via a low-temperature urea-pretreatment induces abundant nitrogen-containing species on the NPC support, thus promoting the affinity of the Pd precursor and hindering the agglomeration of formed Pd NPs onto the NPC surface during the preparation process. Surface-clean Pd NPs with a diameter of sub-2.0 nm deposited on the NPC support (Pd/NPC) exhibit an outstanding catalytic performance with a turnover frequency (TOF) of 2758 h⁻¹ toward DMAB hydrolysis, better than many previous reported Pd-based catalysts. It should be emphasized that the Pd/NPC also possesses a good stability without an obvious decrease in catalytic activity for DMAB hydrolysis in five successive recycling runs. This study provides a facile but efficient way for preparing high-performance Pd catalysts for catalytic hydrogen productions. Full article

(This article belongs to the Special Issue Synthesis of Nanocomposites and Catalysis Applications)

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21 pages, 3726 KiB

Open AccessArticle

Coupling Hydrogenation of Guaiacol with In Situ Hydrogen Production by Glycerol Aqueous Reforming over Ni/Al₂O₃ and Ni-X/Al₂O₃ (X = Cu, Mo, P) Catalysts

by Ziyin Chen, Roman G. Kukushkin, Petr M. Yeletsky, Andrey A. Saraev, Olga A. Bulavchenko and Marcos Millan

Nanomaterials 2020, 10(7), 1420; https://doi.org/10.3390/nano10071420 - 21 Jul 2020

Cited by 12 | Viewed by 3142

Abstract

Biomass-derived liquids, such as bio-oil obtained by fast pyrolysis, can be a valuable source of fuels and chemicals. However, these liquids have high oxygen and water content, needing further upgrading typically involving hydrotreating using H₂ at high pressure and temperature. The harsh [...] Read more.

Biomass-derived liquids, such as bio-oil obtained by fast pyrolysis, can be a valuable source of fuels and chemicals. However, these liquids have high oxygen and water content, needing further upgrading typically involving hydrotreating using H₂ at high pressure and temperature. The harsh reaction conditions and use of expensive H₂ have hindered the progress of this technology and led to the search for alternative processes. In this work, hydrogenation in aqueous phase is investigated using in-situ produced hydrogen from reforming of glycerol, a low-value by-product from biodiesel production, over Ni-based catalysts. Guaiacol was selected as a bio-oil model compound and high conversion (95%) to phenol and aromatic ring hydrogenation products was obtained over Ni/γ-Al₂O₃ at 250 °C and 2-h reaction time. Seventy percent selectivity to cyclohexanol and cyclohexanone was achieved at this condition. Hydrogenation capacity of P and Mo modified Ni/γ-Al₂O₃ was inhibited because more hydrogen undergoes methanation, while Cu showed a good performance in suppressing methane formation. These results demonstrate the feasibility of coupling aqueous phase reforming of glycerol with bio-oil hydrogenation, enabling the reaction to be carried out at lower temperatures and pressures and without the need for molecular H₂. Full article

(This article belongs to the Special Issue Synthesis of Nanocomposites and Catalysis Applications)

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19 pages, 4938 KiB

Open AccessArticle

Nickel-Containing Ceria-Zirconia Doped with Ti and Nb. Effect of Support Composition and Preparation Method on Catalytic Activity in Methane Dry Reforming

by Mikhail Simonov, Yulia Bespalko, Ekaterina Smal, Konstantin Valeev, Valeria Fedorova, Tamara Krieger and Vladislav Sadykov

Nanomaterials 2020, 10(7), 1281; https://doi.org/10.3390/nano10071281 - 30 Jun 2020

Cited by 23 | Viewed by 2884

Abstract

Nickel-containing mixed ceria-zirconia oxides also doped by Nb and Ti have been prepared by a citrate route and by original solvothermal continuous flow synthesis in supercritical alcohols. Nickel was subsequently deposited by conventional insipient wetness impregnation. The oxides are comprised of ceria-zirconia solid [...] Read more.

Nickel-containing mixed ceria-zirconia oxides also doped by Nb and Ti have been prepared by a citrate route and by original solvothermal continuous flow synthesis in supercritical alcohols. Nickel was subsequently deposited by conventional insipient wetness impregnation. The oxides are comprised of ceria-zirconia solid solution with cubic fluorite phase. Negligible amounts of impurities of zirconia are observed for samples prepared by citrate route and doped by Ti. Supports prepared by supercritical synthesis are single-phased. XRD data, Raman, and UV-Vis DR (diffuse reflectance) spectroscopy suggest increasing lattice parameter and amount of oxygen vacancies in fluorite structure after Nb and Ti incorporation despite of the preparation method. These structural changes correlate with the catalytic activity in a methane dry reforming reaction. Catalysts synthesized under supercritical conditions are more active than the catalysts of the same composition prepared by the citrate route. The catalytic activity of samples doped with Ti and Nb is two times higher in terms of TOF (turnover frequency) and increased stability of these catalysts is attributed with the highest oxygen mobility being crucial for gasification of coke precursors. Full article

(This article belongs to the Special Issue Synthesis of Nanocomposites and Catalysis Applications)

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14 pages, 2230 KiB

Open AccessArticle

CuFeAl Nanocomposite Catalysts for Coal Combustion in Fluidized Bed

by Aleksandr V. Fedorov, Nikolay A. Yazykov, Olga A. Bulavchenko, Andrey A. Saraev, Vasily V. Kaichev and Vadim A. Yakovlev

Nanomaterials 2020, 10(5), 1002; https://doi.org/10.3390/nano10051002 - 24 May 2020

Cited by 12 | Viewed by 2654

Abstract

A method of oil-drop granulation was suggested for the preparation of spherical CuFeAl nanocomposite catalysts. The catalysts were characterized by a set of physicochemical methods (X-ray diffraction, temperature-programmed reduction by H₂, low-temperature nitrogen adsorption, crushing strength) and tested in the oxidation [...] Read more.

A method of oil-drop granulation was suggested for the preparation of spherical CuFeAl nanocomposite catalysts. The catalysts were characterized by a set of physicochemical methods (X-ray diffraction, temperature-programmed reduction by H₂, low-temperature nitrogen adsorption, crushing strength) and tested in the oxidation of CO and burning of brown coal in a fluidized bed. It was found that the catalysts have high mechanical strength (16.2 MPa), and their catalytic properties in the oxidation of CO are comparable to the characteristics of industrial Cr-containing catalysts. It was shown that the addition of pseudoboehmite at the stage of drop formation contributes to the production of uniform spherical high-strength granules and facilitates the stabilization of the phase state of the active component. The use of CuFeAl nanocomposite catalysts for the burning of brown coal provides a low emission of CO (600 ppm) and NO_x (220 ppm) and a high degree of coal burnout (95%), which are close to those of the industrial Cr-containing catalysts (emission of CO is 700 ppm, NO_x—230 ppm, and degree of coal burnout is 95%). Full article

(This article belongs to the Special Issue Synthesis of Nanocomposites and Catalysis Applications)

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