Nanomaterials

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11 pages, 3229 KiB

Open AccessArticle

Effect of the TiO₂ Colloidal Size Distribution on the Degradation of Methylene Blue

by So-Yul Kim, Tae-Geol Lee, Seon-Ae Hwangbo and Jong-Ryul Jeong

Nanomaterials 2023, 13(2), 302; https://doi.org/10.3390/nano13020302 - 11 Jan 2023

Cited by 2 | Viewed by 1295

TiO₂ is the most commonly used photocatalyst in water treatment. The particle size of TiO₂ is an important factor that significantly influences its activity during photocatalytic degradation. In the presence of liquid, the properties of nanopowders composed of exactly the same [...] Read more.

TiO₂ is the most commonly used photocatalyst in water treatment. The particle size of TiO₂ is an important factor that significantly influences its activity during photocatalytic degradation. In the presence of liquid, the properties of nanopowders composed of exactly the same product clearly differ according to their aggregation size. In this study, TiO₂ nanoparticles with a controlled size were fabricated by focused ultrasound dispersion. The high energy generated by this system was used to control the size of TiO₂ particles in the suspension. The constant high energy released by cavitation enabled the dispersion of the particles without a surfactant. The activities of the prepared TiO₂ photocatalysts for methylene blue (MB) degradation were then compared. The dye degradation effect of the photocatalyst was as high as 61.7% after 10 min when the size of the powder was controlled in the solution, but it was only as high as 41.0% when the aggregation size was not controlled. Furthermore, when the TiO₂ concentration exceeded a certain level, the photocatalytic activity of TiO₂ decreased. Controlling the size of the aggregated photocatalyst particles is, therefore, essential in water-treatment technologies utilizing TiO₂ photocatalytic properties, and adjusting the TiO₂ concentration is an important economic factor in this photocatalytic technology. This study contributes to the development of processes for degrading dyes, such as MB, released from wastewater into aquatic environments. Full article

(This article belongs to the Special Issue Nanomaterials for Energy Conversion and Catalytic Applications)

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10 pages, 6424 KiB

Open AccessFeature PaperArticle

Size Effect of a Piezoelectric Material as a Separator Coating Layer for Suppressing Dendritic Li Growth in Li Metal Batteries

by Junghwan Kim, Kihwan Kwon, Kwanghyun Kim, Seungmin Han, Patrick Joohyun Kim and Junghyun Choi

Nanomaterials 2023, 13(1), 90; https://doi.org/10.3390/nano13010090 - 24 Dec 2022

Cited by 4 | Viewed by 2265

Abstract

Li metal has been intensively investigated as a next-generation rechargeable battery anode. However, its practical application as the anode material is hindered by the deposition of dendritic Li. To suppress dendritic Li growth, introducing a modified separator is considered an effective strategy since [...] Read more.

Li metal has been intensively investigated as a next-generation rechargeable battery anode. However, its practical application as the anode material is hindered by the deposition of dendritic Li. To suppress dendritic Li growth, introducing a modified separator is considered an effective strategy since it promotes a uniform Li ion flux and strengthens thermal and mechanical stability. Herein, we present a strategy for the surface modification of separator, which involves coating the separator with a piezoelectric material (PM). The PM-coated separator shows higher thermal resistance than the pristine separator, and its modified surface properties enable the homogeneous regulation of the Li-ion flux when the separator is punctured by Li dendrite. Furthermore, PM was synthesized in different solvents via solvothermal method to explore the size effect. This strategy would be helpful to overcome the intrinsic Li metal anode problems. Full article

(This article belongs to the Special Issue Nanomaterials for Energy Conversion and Catalytic Applications)

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10 pages, 2983 KiB

Open AccessArticle

Photocatalysis of Cr- and Fe-Doped CeO₂ Nanoparticles to Selective Oxidation of 5-Hydroxymethylfurfural

by Jeong-Woo Nam, Vy Ngoc Pham, Jeong Min Ha, Minjeong Shin, Hangil Lee and Young-Sang Youn

Nanomaterials 2023, 13(1), 44; https://doi.org/10.3390/nano13010044 - 22 Dec 2022

Cited by 4 | Viewed by 2037

Abstract

Oxygen vacancies (V_o) present in CeO₂ nanoparticles (NPs) can effectively boost their photocatalytic activity under ultraviolet (UV) light. To improve photocatalytic performance, Cr- and Fe-doped CeO₂ NPs with increased V_o were prepared using a simple method of [...] Read more.

Oxygen vacancies (V_o) present in CeO₂ nanoparticles (NPs) can effectively boost their photocatalytic activity under ultraviolet (UV) light. To improve photocatalytic performance, Cr- and Fe-doped CeO₂ NPs with increased V_o were prepared using a simple method of doping Cr and Fe ions into CeO₂ NPs, which was confirmed by an in-depth analysis of the structural and electronic changes. Through photocatalytic degradation (PCD) experiments with 5-hydroxymethylfurfural (HMF), we found that the PCD rates of the two doped CeO₂ NPs were faster than that of the CeO₂ NPs. In addition, the conversion of HMF to 2,5-furandicarboxylic acid (FDCA) using the doped CeO₂ NPs occurred only through the mechanism of the selective oxidation to 5-hydroxymethyl-2-furancarboxylic acid (HMFCA), exhibiting better efficiency than using CeO₂ NPs. Full article

(This article belongs to the Special Issue Nanomaterials for Energy Conversion and Catalytic Applications)

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11 pages, 3974 KiB

Open AccessArticle

Cl- and Al-Doped Argyrodite Solid Electrolyte Li₆PS₅Cl for All-Solid-State Lithium Batteries with Improved Ionic Conductivity

by Yeong Jun Choi, Sun-I Kim, Mingyu Son, Jung Woo Lee and Duck Hyun Lee

Nanomaterials 2022, 12(24), 4355; https://doi.org/10.3390/nano12244355 - 07 Dec 2022

Cited by 7 | Viewed by 3941

Abstract

Argyrodite solid electrolytes such as lithium phosphorus sulfur chloride (Li₆PS₅Cl) have recently attracted great attention due to their excellent lithium-ion transport properties, which are applicable to all-solid-state lithium batteries. In this study, we report the improved ionic conductivity of [...] Read more.

Argyrodite solid electrolytes such as lithium phosphorus sulfur chloride (Li₆PS₅Cl) have recently attracted great attention due to their excellent lithium-ion transport properties, which are applicable to all-solid-state lithium batteries. In this study, we report the improved ionic conductivity of an argyrodite solid electrolyte, Li₆PS₅Cl, in all-solid-state lithium batteries via the co-doping of chlorine (Cl) and aluminum (Al) elements. Electrochemical analysis was conducted on the doped argyrodite structure of Li₆PS₅Cl, which revealed that the substitution of cations and anions greatly improved the ionic conductivity of solid electrolytes. The ionic conductivity of the Cl- and Al-doped Li₆PS₅Cl (Li_5.4Al_0.1PS_4.7Cl_1.3) electrolyte was 7.29 × 10⁻³ S cm⁻¹ at room temperature, which is 4.7 times higher than that of Li₆PS₅Cl. The Arrhenius plot of the Li_5.4Al_0.1PS_4.7Cl_1.3 electrolyte further elucidated its low activation energy at 0.09 eV. Full article

(This article belongs to the Special Issue Nanomaterials for Energy Conversion and Catalytic Applications)

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12 pages, 2924 KiB

Open AccessArticle

Polyol-Mediated Synthesis of V₂O₅–WO₃/TiO₂ Catalysts for Low-Temperature Selective Catalytic Reduction with Ammonia

by Min Seong Lee, Yeong Jun Choi, Su-Jeong Bak, Mingyu Son, Jeehoon Shin and Duck Hyun Lee

Nanomaterials 2022, 12(20), 3644; https://doi.org/10.3390/nano12203644 - 18 Oct 2022

Cited by 4 | Viewed by 1458

Abstract

We demonstrated highly efficient selective catalytic reduction catalysts by adopting the polyol process, and the prepared catalysts exhibited a high nitrogen oxide (NO_X) removal efficiency of 96% at 250 °C. The V₂O₅ and WO₃ catalyst nanoparticles prepared [...] Read more.

We demonstrated highly efficient selective catalytic reduction catalysts by adopting the polyol process, and the prepared catalysts exhibited a high nitrogen oxide (NO_X) removal efficiency of 96% at 250 °C. The V₂O₅ and WO₃ catalyst nanoparticles prepared using the polyol process were smaller (~10 nm) than those prepared using the impregnation method (~20 nm), and the small catalyst size enabled an increase in surface area and catalytic acid sites. The NO_X removal efficiencies at temperatures between 200 and 250 °C were enhanced by approximately 30% compared to those of the catalysts prepared using the conventional impregnation method. The NH₃-temperature-programmed desorption and H₂-temperature-programmed reduction results confirmed that the polyol process produced more surface acid sites at low temperatures and enhanced the redox ability. The in situ Fourier-transform infrared spectra further elucidated the fast absorption of NH₃ and its reduction with NO and O₂ on the prepared catalyst surfaces. This study provides an effective approach to synthesizing efficient low-temperature SCR catalysts and may contribute to further studies related to other catalytic systems. Full article

(This article belongs to the Special Issue Nanomaterials for Energy Conversion and Catalytic Applications)

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12 pages, 3144 KiB

Open AccessArticle

Enhanced Visible-Light-Driven Photocatalysis of Ag/Ag₂O/ZnO Nanocomposite Heterostructures

by Chadrasekhar Loka and Kee-Sun Lee

Nanomaterials 2022, 12(15), 2528; https://doi.org/10.3390/nano12152528 - 23 Jul 2022

Cited by 19 | Viewed by 2187

Abstract

Visible-light-driven photocatalysis is one promising and efficient approach for decontaminating pollutants. Herein, we report the combination of localized surface plasmon resonance (LSPR) and p-n heterojunction structure Ag-Ag₂O-ZnO nanocomposite synthesized by a hydrothermal process for the suppression of photogenerated electron-hole pair recombination [...] Read more.

Visible-light-driven photocatalysis is one promising and efficient approach for decontaminating pollutants. Herein, we report the combination of localized surface plasmon resonance (LSPR) and p-n heterojunction structure Ag-Ag₂O-ZnO nanocomposite synthesized by a hydrothermal process for the suppression of photogenerated electron-hole pair recombination rates, the extension of the absorption edge to the visible region, and the enhancement of photocatalytic efficiency. The prepared nanocomposites were investigated by standard analytical techniques and the results revealed that the synthesized powders were comprised of Ag, Ag₂O, and ZnO phases. Photocatalytic activity of the photocatalyst tested for methylene blue, methyl orange, and rhodamine B showed the highest photocatalytic degradation efficiency: 97.3%, 91.1%, and 94.8% within 60 min under visible-light irradiation. The average lifetime of the photogenerated charge carriers was increased twofold in the Ag-Ag₂O-ZnO photocatalyst (~10 ns) compared to the pure ZnO (~5.2 ns). The enhanced photocatalytic activity resulted from a decrease of the charge carrier recombination rate as inferred from the steady-state and time-resolved photoluminescence investigations, and the increased photoabsorption ability. The Ag-Ag₂O-ZnO photocatalyst was stable over five repeated cyclic photodegradation tests without showing any significant changes in performance. Additionally, the structure indicated a potential for application in environmental remediation. The present study showcases the robust design of highly efficient and reusable visible-light-active photocatalysts via the combination of p-n heterojunction and LSPR phenomena. Full article

(This article belongs to the Special Issue Nanomaterials for Energy Conversion and Catalytic Applications)

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15 pages, 5903 KiB

Open AccessFeature PaperArticle

Phase-Controlled NiO Nanoparticles on Reduced Graphene Oxide as Electrocatalysts for Overall Water Splitting

by Seung Geun Jo, Chung-Soo Kim, Sang Jun Kim and Jung Woo Lee

Nanomaterials 2021, 11(12), 3379; https://doi.org/10.3390/nano11123379 - 13 Dec 2021

Cited by 17 | Viewed by 2978

Abstract

Efficient water electrolysis is one of the key issues in realizing a clean and renewable energy society based on hydrogen fuel. However, several obstacles remain to be solved for electrochemical water splitting catalysts, which are the high cost of noble metals and the [...] Read more.

Efficient water electrolysis is one of the key issues in realizing a clean and renewable energy society based on hydrogen fuel. However, several obstacles remain to be solved for electrochemical water splitting catalysts, which are the high cost of noble metals and the high overpotential of alternative catalysts. Herein, we suggest Ni-based alternative catalysts that have comparable performances with precious metal-based catalysts and could be applied to both cathode and anode by precise phase control of the pristine catalyst. A facile microwave-assisted procedure was used for NiO nanoparticles anchored on reduced graphene oxide (NiO NPs/rGO) with uniform size distribution in ~1.8 nm. Subsequently, the Ni-NiO dual phase of the NPs (A-NiO NPs/rGO) could be obtained via tailored partial reduction of the NiO NPs/rGO. Moreover, we demonstrate from systematic HADDF-EDS and XPS analyses that metallic Ni could be formed in a local area of the NiO NP after the reductive annealing procedure. Indeed, the synergistic catalytic performance of the Ni-NiO phase of the A-NiO NPs/rGO promoted hydrogen evolution reaction activity with an overpotential as 201 mV at 10 mA cm⁻², whereas the NiO NPs/rGO showed 353 mV. Meanwhile, the NiO NPs/rGO exhibited the most excellent oxygen evolution reaction performance among all of the Ni-based catalysts, with an overpotential of 369 mV at 10 mA cm⁻², indicating that they could be selectively utilized in the overall water splitting. Furthermore, both catalysts retained their activities over 12 h with constant voltage and 1000 cycles under cyclic redox reaction, proving their high durability. Finally, the full cell capability for the overall water electrolysis system was confirmed by observing the generation of hydrogen and oxygen on the surface of the cathode and anode. Full article

(This article belongs to the Special Issue Nanomaterials for Energy Conversion and Catalytic Applications)

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13 pages, 3946 KiB

Open AccessArticle

Nitrogen-Doped Reduced Graphene Oxide Supported Pd_4.7Ru Nanoparticles Electrocatalyst for Oxygen Reduction Reaction

by Gil-Ryeong Park, Seung Geun Jo, Anuraj Varyambath, Jeonghyun Kim and Jung Woo Lee

Nanomaterials 2021, 11(10), 2727; https://doi.org/10.3390/nano11102727 - 15 Oct 2021

Cited by 5 | Viewed by 2687

Abstract

It is imperative to design an inexpensive, active, and durable electrocatalyst in oxygen reduction reaction (ORR) to replace carbon black supported Pt (Pt/CB). In this work, we synthesized Pd_4.7Ru nanoparticles on nitrogen-doped reduced graphene oxide (Pd_4.7Ru NPs/NrGO) by a [...] Read more.

It is imperative to design an inexpensive, active, and durable electrocatalyst in oxygen reduction reaction (ORR) to replace carbon black supported Pt (Pt/CB). In this work, we synthesized Pd_4.7Ru nanoparticles on nitrogen-doped reduced graphene oxide (Pd_4.7Ru NPs/NrGO) by a facile microwave-assisted method. Nitrogen atoms were introduced into the graphene by thermal reduction with NH₃ gas and several nitrogen atoms, such as pyrrolic, graphitic, and pyridinic N, found by X-ray photoelectron spectroscopy. Pyridinic nitrogen atoms acted as efficient particle anchoring sites, making strong bonding with Pd_4.7Ru NPs. Additionally, carbon atoms bonding with pyridinic N facilitated the adsorption of O₂ as Lewis bases. The uniformly distributed ~2.4 nm of Pd_4.7Ru NPs on the NrGO was confirmed by transmission electron microscopy. The optimal composition between Pd and Ru is 4.7:1, reaching −6.33 mA/cm² at 0.3 V_RHE for the best ORR activity among all measured catalysts. Furthermore, accelerated degradation test by electrochemical measurements proved its high durability, maintaining its initial current density up to 98.3% at 0.3 V_RHE and 93.7% at 0.75 V_RHE, whereas other catalysts remained below 90% at all potentials. These outcomes are considered that the doped nitrogen atoms bond with the NPs stably, and their electron-rich states facilitate the interaction with the reactants on the surface. In conclusion, the catalyst can be applied to the fuel cell system, overcoming the high cost, activity, and durability issues. Full article

(This article belongs to the Special Issue Nanomaterials for Energy Conversion and Catalytic Applications)

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19 pages, 4609 KiB

Open AccessArticle

Effect of Sn Doping on Pd Electro-Catalysts for Enhanced Electro-Catalytic Activity towards Methanol and Ethanol Electro-Oxidation in Direct Alcohol Fuel Cells

by Cyril Tlou Selepe, Sandile Surprise Gwebu, Thabo Matthews, Tebogo Abigail Mashola, Ludwe Luther Sikeyi, Memory Zikhali and Nobanathi Wendy Maxakato

Nanomaterials 2021, 11(10), 2725; https://doi.org/10.3390/nano11102725 - 15 Oct 2021

Cited by 12 | Viewed by 2290

Abstract

Carbon nano-onions (CNOs) were successfully synthesized by employing the flame pyrolysis (FP) method, using flaxseed oil as a carbon source. The alcohol reduction method was used to prepare Pd/CNOs and Pd-Sn/CNOs electro-catalysts, with ethylene glycol as the solvent and reduction agent. The metal-nanoparticles [...] Read more.

Carbon nano-onions (CNOs) were successfully synthesized by employing the flame pyrolysis (FP) method, using flaxseed oil as a carbon source. The alcohol reduction method was used to prepare Pd/CNOs and Pd-Sn/CNOs electro-catalysts, with ethylene glycol as the solvent and reduction agent. The metal-nanoparticles were supported on the CNO surface without adjusting the pH of the solution. High-resolution transmission electron microscopy (HRTEM) images reveal CNOs with concentric graphite ring morphology, and also PdSn nanoparticles supported on the CNOs. X-ray diffractometry (XRD) patterns confirm that CNOs are amorphous and show the characteristic diffraction peaks of Pd. There is a shifting of Pd diffraction peaks to lower angles upon the addition of Sn compared to Pd/CNOs. X-ray photoelectron spectroscopy (XPS) results also confirm the doping of Pd with Sn to form a PdSn alloy. Fourier transform infrared spectroscopy (FTIR) displays oxygen, hydroxyl, carboxyl, and carbonyl, which facilitates the dispersion of Pd and Sn nanoparticles. Raman spectrum displays two prominent peaks of carbonaceous materials which correspond to the D and G bands. The Pd-Sn/CNOs electro-catalyst demonstrates improved electro-oxidation of methanol and ethanol performance compared to Pd/CNOs and commercial Pd/C electro-catalysts under alkaline conditions. Full article

(This article belongs to the Special Issue Nanomaterials for Energy Conversion and Catalytic Applications)

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10 pages, 4687 KiB

Open AccessArticle

Reduced Graphene-Oxide-Encapsulated MoS₂/Carbon Nanofiber Composite Electrode for High-Performance Na-Ion Batteries

by Su-Ho Cho, Jong-Heon Kim, Il-Gyu Kim, Jeong-Ho Park, Ji-Won Jung, Hyun-Suk Kim and Il-Doo Kim

Nanomaterials 2021, 11(10), 2691; https://doi.org/10.3390/nano11102691 - 13 Oct 2021

Cited by 11 | Viewed by 2547

Abstract

Sodium-ion batteries (SIBs) have been increasingly studied due to sodium (Na) being an inexpensive ionic resource (Na) and their battery chemistry being similar to that of current lithium-ion batteries (LIBs). However, SIBs have faced substantial challenges in developing high-performance anode materials that can [...] Read more.

Sodium-ion batteries (SIBs) have been increasingly studied due to sodium (Na) being an inexpensive ionic resource (Na) and their battery chemistry being similar to that of current lithium-ion batteries (LIBs). However, SIBs have faced substantial challenges in developing high-performance anode materials that can reversibly store Na⁺ in the host structure. To address these challenges, molybdenum sulfide (MoS₂)-based active materials have been considered as promising anodes, owing to the two-dimensional layered structure of MoS₂ for stably (de)inserting Na⁺. Nevertheless, intrinsic issues of MoS₂—such as low electronic conductivity and the loss of active S elements after a conversion reaction—have limited the viability of MoS₂ in practical SIBs. Here, we report MoS₂ embedded in carbon nanofibers encapsulated with a reduced graphene oxide (MoS₂@CNFs@rGO) composite for SIB anodes. The MoS₂@CNFs@rGO delivered a high capacity of 345.8 mAh g⁻¹ at a current density of 100 mA g⁻¹ for 90 cycles. The CNFs and rGO were synergistically taken into account for providing rapid pathways for electrons and preventing the dissolution of S sources during repetitive conversion reactions. This work offers a new point of view to realize MoS₂-based anode materials in practical SIBs. Full article

(This article belongs to the Special Issue Nanomaterials for Energy Conversion and Catalytic Applications)

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11 pages, 2949 KiB

Open AccessEditor’s ChoiceArticle

Ammonium Ion Enhanced V₂O₅-WO₃/TiO₂ Catalysts for Selective Catalytic Reduction with Ammonia

by Min Seong Lee, Sun-I Kim, Bora Jeong, Jin-Woo Park, Taehyo Kim, Jung Woo Lee, Gibum Kwon and Duck Hyun Lee

Nanomaterials 2021, 11(10), 2677; https://doi.org/10.3390/nano11102677 - 12 Oct 2021

Cited by 7 | Viewed by 2080

Abstract

Selective catalytic reduction (SCR) is the most efficient NO_X removal technology, and the vanadium-based catalyst is mainly used in SCR technology. The vanadium-based catalyst showed higher NO_X removal performance in the high-temperature range but catalytic efficiency decreased at lower temperatures, following [...] Read more.

Selective catalytic reduction (SCR) is the most efficient NO_X removal technology, and the vanadium-based catalyst is mainly used in SCR technology. The vanadium-based catalyst showed higher NO_X removal performance in the high-temperature range but catalytic efficiency decreased at lower temperatures, following exposure to SO_X because of the generation of ammonium sulfate on the catalyst surface. To overcome these limitations, we coated an NH₄⁺ layer on a vanadium-based catalyst. After silane coating the V₂O₅-WO₃/TiO₂ catalyst by vapor evaporation, the silanized catalyst was heat treated under NH₃ gas. By decomposing the silane on the surface, an NH₄⁺ layer was formed on the catalyst surface through a substitution reaction. We observed high NO_X removal efficiency over a wide temperature range by coating an NH₄⁺ layer on a vanadium-based catalyst. This layer shows high proton conductivity, which leads to the reduction of vanadium oxides and tungsten oxide; additionally, the NO_X removal performance was improved over a wide temperature range. These findings provide a new mothed to develop SCR catalyst with high efficiency at a wide temperature range. Full article

(This article belongs to the Special Issue Nanomaterials for Energy Conversion and Catalytic Applications)

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20 pages, 4821 KiB

Open AccessArticle

Fabrication and Application of Zeolite/Acanthophora Spicifera Nanoporous Composite for Adsorption of Congo Red Dye from Wastewater

by Ahmed Hamd, Asmaa Ragab Dryaz, Mohamed Shaban, Hamad AlMohamadi, Khulood A. Abu Al-Ola, Nofal Khamis Soliman and Sayed A. Ahmed

Nanomaterials 2021, 11(9), 2441; https://doi.org/10.3390/nano11092441 - 19 Sep 2021

Cited by 25 | Viewed by 2321

Abstract

Systematic investigations involving laboratory, analytical, and field trials were carried out to obtain the most efficient adsorbent for the removal of congo red (CR) dye from industrial effluent. Modification of the zeolite (Z) by the Acanthophora Spicifera algae (AS; marine algae) was evaluated [...] Read more.

Systematic investigations involving laboratory, analytical, and field trials were carried out to obtain the most efficient adsorbent for the removal of congo red (CR) dye from industrial effluent. Modification of the zeolite (Z) by the Acanthophora Spicifera algae (AS; marine algae) was evaluated in terms of adsorption capability of the zeolite to remove CR dye from aqueous solution. The zeolite/algae composite (ZAS) was fabricated using the wet impregnation technique. The AS, Z, and the synthesized ZAS composite were analyzed utilizing various characterization techniques. The newly synthesized ZAS composite has an adsorption capacity that is significantly higher than that of Z and AS, particularly at low CR concentrations. Batch experiments were carried out to explore the effects of different experimental factors, as well as the dye adsorption isotherms and kinetics. Owing to the presence of intermolecular interactions, the computational analysis showed that the adsorption of the CR molecule on zeolite surfaces is exothermic, energetically favorable, and spontaneous. Furthermore, growing the zeolite surface area has no discernible effect on the adsorption energies in all configurations. The ZAS composite may be used as a low-cost substitute adsorbent for the removal of anionic dyes from industrial wastewater at lower dye concentrations, according to the experimental results. Adsorption of CR dye onto Z, AS, and ZAS adsorbents was adequately explained by pseudo-second-order kinetics and the Langmuir isotherm. The sorption mechanism was also evaluated using Weber’s intra-particle diffusion module. Finally, field testing revealed that the newly synthesized adsorbent was 98.0% efficient at extracting dyes from industrial wastewater, proving the foundation of modern eco-friendly materials that aid in the reuse of industrial wastewater. Full article

(This article belongs to the Special Issue Nanomaterials for Energy Conversion and Catalytic Applications)

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12 pages, 2174 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Effect of Catalyst Crystallinity on V-Based Selective Catalytic Reduction with Ammonia

by Min Seong Lee, Sun-I Kim, Myeung-jin Lee, Bora Ye, Taehyo Kim, Hong-Dae Kim, Jung Woo Lee and Duck Hyun Lee

Nanomaterials 2021, 11(6), 1452; https://doi.org/10.3390/nano11061452 - 30 May 2021

Cited by 11 | Viewed by 2684

Abstract

In this study, we synthesized V₂O₅-WO₃/TiO₂ catalysts with different crystallinities via one-sided and isotropic heating methods. We then investigated the effects of the catalysts’ crystallinity on their acidity, surface species, and catalytic performance through various analysis [...] Read more.

In this study, we synthesized V₂O₅-WO₃/TiO₂ catalysts with different crystallinities via one-sided and isotropic heating methods. We then investigated the effects of the catalysts’ crystallinity on their acidity, surface species, and catalytic performance through various analysis techniques and a fixed-bed reactor experiment. The isotropic heating method produced crystalline V₂O₅ and WO₃, increasing the availability of both Brønsted and Lewis acid sites, while the one-sided method produced amorphous V₂O₅ and WO₃. The crystalline structure of the two species significantly enhanced NO₂ formation, causing more rapid selective catalytic reduction (SCR) reactions and greater catalyst reducibility for NO_X decomposition. This improved NO_X removal efficiency and N₂ selectivity for a wider temperature range of 200 °C–450 °C. Additionally, the synthesized, crystalline catalysts exhibited good resistance to SO₂, which is common in industrial flue gases. Through the results reported herein, this study may contribute to future studies on SCR catalysts and other catalyst systems. Full article

(This article belongs to the Special Issue Nanomaterials for Energy Conversion and Catalytic Applications)

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9 pages, 2392 KiB

Open AccessArticle

Plasma-Enhanced Atomic Layer Deposition of TiN Thin Films as an Effective Se Diffusion Barrier for CIGS Solar Cells

by Hyun-Jae Woo, Woo-Jae Lee, Eun-Kyong Koh, Seung Il Jang, Shinho Kim, Hyoungseok Moon and Se-Hun Kwon

Nanomaterials 2021, 11(2), 370; https://doi.org/10.3390/nano11020370 - 02 Feb 2021

Cited by 6 | Viewed by 2822

Abstract

Plasma-enhanced atomic layer deposition (PEALD) of TiN thin films were investigated as an effective Se diffusion barrier layer for Cu (In, Ga) Se₂ (CIGS) solar cells. Before the deposition of TiN thin film on CIGS solar cells, a saturated growth rate of [...] Read more.

Plasma-enhanced atomic layer deposition (PEALD) of TiN thin films were investigated as an effective Se diffusion barrier layer for Cu (In, Ga) Se₂ (CIGS) solar cells. Before the deposition of TiN thin film on CIGS solar cells, a saturated growth rate of 0.67 Å/cycle was confirmed using tetrakis(dimethylamido)titanium (TDMAT) and N₂ plasma at 200 °C. Then, a Mo (≈30 nm)/PEALD-TiN (≈5 nm)/Mo (≈600 nm) back contact stack was fabricated to investigate the effects of PEALD-TiN thin films on the Se diffusion. After the selenization process, it was revealed that ≈5 nm-thick TiN thin films can effectively block Se diffusion and that only the top Mo layer prepared on the TiN thin films reacted with Se to form a MoSe₂ layer. Without the TiN diffusion barrier layer, however, Se continuously diffused along the grain boundaries of the entire Mo back contact electrode. Finally, the adoption of a TiN diffusion barrier layer improved the photovoltaic efficiency of the CIGS solar cell by approximately 10%. Full article

(This article belongs to the Special Issue Nanomaterials for Energy Conversion and Catalytic Applications)

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