Pub Date : 2025-02-21DOI: 10.1021/acs.langmuir.4c04741
Cuong Nguyen, Jeffrey J. Weimer
This work defines how the deposition method, deposition volume, dispersion density, and film expansion mode influence and therefore may be controlled to improve uniformity in Langmuir films of nanoparticles. We used fluorescence imaging of quantum dots with oleic acid ligands. We first establish why future work with Langmuir films of nanoparticles should avoid using a drop method of deposition, whereby the dispersion falls onto the subphase. The preferred method should be a touch method, whereby a meniscus of the dispersion touches the surface of the subphase, and either is allowed to be captured by or is pushed onto the subphase. For free expansion of films, deposition volume defines the final spread area of films, whereas dispersion mass loading (volume times dispersion density) establishes the average overall area number density of nanoparticles in the final film. We demonstrate that films spreading in free expansion retain a coffee-ring pattern even after they collapse freely to a final, steady-state size. The final films contain various microstructures, including layers in the outer rings as well as clusters, chains, or networks in the inner open region, depending on initial dispersion mass loading. We propose that allowing free expansion of Langmuir films of nanoparticles should not be preferred to achieve consistently uniform films over the entire area, even when the final films might be post-processed by compression + expansion isotherm steps. Finally, we explore the effects of setting a physical boundary on the expansion. Constrained expansion is defined as a ratio of constraint area to maximum spread area below unity. We establish that the deposition of Langmuir films of nanoparticles using constrained expansion offers a reproducible and robustly viable method to create spontaneously self-assembled, uniform (monolayer) Langmuir films of nanoparticles, with the uniformity extending over the entire film.
{"title":"Toward Improving the Overall Uniformity in Langmuir Films of Nanoparticles by Controlling the Initial Deposition Parameters","authors":"Cuong Nguyen, Jeffrey J. Weimer","doi":"10.1021/acs.langmuir.4c04741","DOIUrl":"https://doi.org/10.1021/acs.langmuir.4c04741","url":null,"abstract":"This work defines how the deposition method, deposition volume, dispersion density, and film expansion mode influence and therefore may be controlled to improve uniformity in Langmuir films of nanoparticles. We used fluorescence imaging of quantum dots with oleic acid ligands. We first establish why future work with Langmuir films of nanoparticles should avoid using a drop method of deposition, whereby the dispersion falls onto the subphase. The preferred method should be a touch method, whereby a meniscus of the dispersion touches the surface of the subphase, and either is allowed to be captured by or is pushed onto the subphase. For free expansion of films, deposition volume defines the final spread area of films, whereas dispersion mass loading (volume times dispersion density) establishes the average overall area number density of nanoparticles in the final film. We demonstrate that films spreading in free expansion retain a coffee-ring pattern even after they collapse freely to a final, steady-state size. The final films contain various microstructures, including layers in the outer rings as well as clusters, chains, or networks in the inner open region, depending on initial dispersion mass loading. We propose that allowing free expansion of Langmuir films of nanoparticles should not be preferred to achieve consistently uniform films over the entire area, even when the final films might be post-processed by compression + expansion isotherm steps. Finally, we explore the effects of setting a physical boundary on the expansion. Constrained expansion is defined as a ratio of constraint area to maximum spread area below unity. We establish that the deposition of Langmuir films of nanoparticles using constrained expansion offers a reproducible and robustly viable method to create spontaneously self-assembled, uniform (monolayer) Langmuir films of nanoparticles, with the uniformity extending over the entire film.","PeriodicalId":50,"journal":{"name":"Langmuir","volume":"85 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143470546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-21DOI: 10.1021/acs.langmuir.4c04605
Yi Sun, Wenlong Sun, KangKang Zhang, Siyu Cui, Xiong Shao, Jian Qiu, Yushan Yang, Jun Li
In order to improve the specimens’ flame-retardant qualities, ethyl orthosilicate was impregnated into them using a combination of the delignification process and the in situ growing approach. Lignification has been demonstrated to increase the cellular gap of the specimen and to maximize the impregnation of ethyl orthosilicate. Moreover, the in situ growth method results in the combination of specimens containing silica manufactured from ethyl orthosilicate, thereby forming a composite material with enhanced flame-retardant properties. The examination of the changes in the properties of the specimens before and after modification was conducted using FTIR spectroscopy, XRD, XPS, SEM, and other experimental techniques. The modified specimens exhibited higher properties in comparison to the untreated specimens. Furthermore, the modified specimens exhibited enhanced mechanical properties, characterized by an augmented compressive strength of 34.9 MPa and a strength-to-weight ratio of 158 MPa·cm·g–1, in comparison to specimens that did not undergo the modification process. The results of experiments show that proposed green technology provides a new method for producing flame-retardant composites and could significantly improve the mechanical and flame-retardant qualities of wood.
{"title":"Designing Highly Flame-Retardant Wood Through an In Situ Chemical Modification Strategy","authors":"Yi Sun, Wenlong Sun, KangKang Zhang, Siyu Cui, Xiong Shao, Jian Qiu, Yushan Yang, Jun Li","doi":"10.1021/acs.langmuir.4c04605","DOIUrl":"https://doi.org/10.1021/acs.langmuir.4c04605","url":null,"abstract":"In order to improve the specimens’ flame-retardant qualities, ethyl orthosilicate was impregnated into them using a combination of the delignification process and the in situ growing approach. Lignification has been demonstrated to increase the cellular gap of the specimen and to maximize the impregnation of ethyl orthosilicate. Moreover, the in situ growth method results in the combination of specimens containing silica manufactured from ethyl orthosilicate, thereby forming a composite material with enhanced flame-retardant properties. The examination of the changes in the properties of the specimens before and after modification was conducted using FTIR spectroscopy, XRD, XPS, SEM, and other experimental techniques. The modified specimens exhibited higher properties in comparison to the untreated specimens. Furthermore, the modified specimens exhibited enhanced mechanical properties, characterized by an augmented compressive strength of 34.9 MPa and a strength-to-weight ratio of 158 MPa·cm·g<sup>–1</sup>, in comparison to specimens that did not undergo the modification process. The results of experiments show that proposed green technology provides a new method for producing flame-retardant composites and could significantly improve the mechanical and flame-retardant qualities of wood.","PeriodicalId":50,"journal":{"name":"Langmuir","volume":"25 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143463059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-21DOI: 10.1021/acs.langmuir.5c00361
Dage Liu, Lina A. Gugliotti, Tong Wu, Magda Dolska, Alexander G. Tkachenko, Mathew K. Shipton, Bruce E. Eaton, Daniel L. Feldheim
The Editor retracts this article (DOI: 10.1021/la060426c) due to its reliance on findings from a previously published article, “RNA-Mediated Metal–Metal Bond Formation in the Synthesis of Hexagonal Palladium Nanoparticles” (DOI: 10.1126/science.1095678) which was retracted (DOI: 10.1126/science.351.6273.569-a) following an investigation by the U.S. National Science Foundation’s (NSF) Office of Inspector General. The experiments presented in the article are based on retracted premises, and concerns about the integrity of the research findings remain unresolved, as the authors could not be reached for a response. As such, the article is being retracted. The original article was published on May 17, 2006, and was retracted on February 21, 2025. This article has not yet been cited by other publications.
{"title":"Retraction of “RNA-Mediated Synthesis of Palladium Nanoparticles on Au Surfaces”","authors":"Dage Liu, Lina A. Gugliotti, Tong Wu, Magda Dolska, Alexander G. Tkachenko, Mathew K. Shipton, Bruce E. Eaton, Daniel L. Feldheim","doi":"10.1021/acs.langmuir.5c00361","DOIUrl":"https://doi.org/10.1021/acs.langmuir.5c00361","url":null,"abstract":"The Editor retracts this article (DOI: 10.1021/la060426c) due to its reliance on findings from a previously published article, “RNA-Mediated Metal–Metal Bond Formation in the Synthesis of Hexagonal Palladium Nanoparticles” (DOI: 10.1126/science.1095678) which was retracted (DOI: 10.1126/science.351.6273.569-a) following an investigation by the U.S. National Science Foundation’s (NSF) Office of Inspector General. The experiments presented in the article are based on retracted premises, and concerns about the integrity of the research findings remain unresolved, as the authors could not be reached for a response. As such, the article is being retracted. The original article was published on May 17, 2006, and was retracted on February 21, 2025. This article has not yet been cited by other publications.","PeriodicalId":50,"journal":{"name":"Langmuir","volume":"20 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143463060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study investigates the removal of pharmaceutical contaminants ibuprofen and diclofenac from aqueous solutions using graphene oxide (GO) coated with cetyltrimethylammonium bromide (CTAB) as a nanocomposite in a fully pressurized dissolved air flotation process. This novel approach leverages the surface-active properties of GO–CTAB to efficiently eliminate pharmaceuticals under optimized conditions. Characterization techniques, including Fourier transform infrared (FTIR), ζ-potential, particle size analysis, surface tension measurements, contact angle assessment, Brunauer–Emmett–Teller (BET) analysis, Gas chromatography–mass spectrometry (GC–MS), and Field emission scanning electron microscopy (FE-SEM) Energy-dispersive X-ray spectroscopy (EDS), validated the successful synthesis and efficacy of the GO–CTAB nanocomposite in pollutant removal. The process parameters were optimized, with the highest removal efficiencies achieved at a pH of 5 for ibuprofen and pH 4 for diclofenac, a surfactant dosage of 0.4 g, a pressure of 15 psig, and a rate of flow of 0.5 L/min. Under these conditions, removal efficiencies of 99.29% for ibuprofen and 95.31% for diclofenac were obtained, demonstrating the high performance of the GO–CTAB nanocomposite in treating low-concentration pharmaceutical contaminants. This study underscores the potential of the GO–CTAB flotation process as a sustainable, eco-friendly, and highly effective solution for pharmaceutical wastewater treatment, offering sustainability while minimizing chemical usage and environmental impact.
{"title":"Enhanced Flotation for the Removal of Pharmaceutical Contaminants from Water Systems Using Graphene Oxide–CTAB Nanocomposites","authors":"Gowri Pooja, Ponnusamy Senthil Kumar, Chitra Boobalan, Gayathri Rangasamy","doi":"10.1021/acs.langmuir.4c04066","DOIUrl":"https://doi.org/10.1021/acs.langmuir.4c04066","url":null,"abstract":"This study investigates the removal of pharmaceutical contaminants ibuprofen and diclofenac from aqueous solutions using graphene oxide (GO) coated with cetyltrimethylammonium bromide (CTAB) as a nanocomposite in a fully pressurized dissolved air flotation process. This novel approach leverages the surface-active properties of GO–CTAB to efficiently eliminate pharmaceuticals under optimized conditions. Characterization techniques, including Fourier transform infrared (FTIR), ζ-potential, particle size analysis, surface tension measurements, contact angle assessment, Brunauer–Emmett–Teller (BET) analysis, Gas chromatography–mass spectrometry (GC–MS), and Field emission scanning electron microscopy (FE-SEM) Energy-dispersive X-ray spectroscopy (EDS), validated the successful synthesis and efficacy of the GO–CTAB nanocomposite in pollutant removal. The process parameters were optimized, with the highest removal efficiencies achieved at a pH of 5 for ibuprofen and pH 4 for diclofenac, a surfactant dosage of 0.4 g, a pressure of 15 psig, and a rate of flow of 0.5 L/min. Under these conditions, removal efficiencies of 99.29% for ibuprofen and 95.31% for diclofenac were obtained, demonstrating the high performance of the GO–CTAB nanocomposite in treating low-concentration pharmaceutical contaminants. This study underscores the potential of the GO–CTAB flotation process as a sustainable, eco-friendly, and highly effective solution for pharmaceutical wastewater treatment, offering sustainability while minimizing chemical usage and environmental impact.","PeriodicalId":50,"journal":{"name":"Langmuir","volume":"3 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143463201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-21DOI: 10.1021/acs.langmuir.5c00028
Jyoti Saini, Mamta Raturi, Manpreet Kaur, Km Neeshu, Akash Kumar Maharana, Tapaswini Dash, Amal Kishore, Himanshu Tyagi, Renu Rani, Anirban Kundu, Abir De Sarkar, Kiran Shankar Hazra
Graphene-based room-temperature bolometers with a high-temperature coefficient of resistance (TCR) and fast response times are emerging as promising technologies for thermal imaging, temperature sensing, and infrared (IR) detection. However, achieving high sensitivity in pristine graphene at ambient temperatures has been challenging due to weak electron–phonon interactions, which suppress the temperature dependence of the resistance. In this study, we propose a flexible microbolometer based on a reduced graphene oxide (rGO) and chitosan (CS) hybrid, which demonstrates a bolometric response at room temperature. The enhanced nitrogen functional groups in rGO, derived from chitosan treatment, act as defect centers that promote defect-assisted electron–phonon scattering (supercollision scattering), effectively overcoming the weak electron–phonon interaction at room temperature. Chitosan further enhances nitrogen functionality and imparts flexibility to the bolometer, leading to an improved TCR and durability. Our results show a maximum TCR of ∼3.1%/K, a current responsivity of ∼10.84 μA/W, and a thermal response time in the millisecond range for the nitro-boosted rGO–CS microbolometer near room temperature. This work presents a novel pathway for room-temperature bolometers, leveraging nitrogen-driven supercollision scattering in an rGO–CS hybrid.
{"title":"Room-Temperature Bolometric Response in Nitro-Boosted rGO","authors":"Jyoti Saini, Mamta Raturi, Manpreet Kaur, Km Neeshu, Akash Kumar Maharana, Tapaswini Dash, Amal Kishore, Himanshu Tyagi, Renu Rani, Anirban Kundu, Abir De Sarkar, Kiran Shankar Hazra","doi":"10.1021/acs.langmuir.5c00028","DOIUrl":"https://doi.org/10.1021/acs.langmuir.5c00028","url":null,"abstract":"Graphene-based room-temperature bolometers with a high-temperature coefficient of resistance (TCR) and fast response times are emerging as promising technologies for thermal imaging, temperature sensing, and infrared (IR) detection. However, achieving high sensitivity in pristine graphene at ambient temperatures has been challenging due to weak electron–phonon interactions, which suppress the temperature dependence of the resistance. In this study, we propose a flexible microbolometer based on a reduced graphene oxide (rGO) and chitosan (CS) hybrid, which demonstrates a bolometric response at room temperature. The enhanced nitrogen functional groups in rGO, derived from chitosan treatment, act as defect centers that promote defect-assisted electron–phonon scattering (supercollision scattering), effectively overcoming the weak electron–phonon interaction at room temperature. Chitosan further enhances nitrogen functionality and imparts flexibility to the bolometer, leading to an improved TCR and durability. Our results show a maximum TCR of ∼3.1%/K, a current responsivity of ∼10.84 μA/W, and a thermal response time in the millisecond range for the nitro-boosted rGO–CS microbolometer near room temperature. This work presents a novel pathway for room-temperature bolometers, leveraging nitrogen-driven supercollision scattering in an rGO–CS hybrid.","PeriodicalId":50,"journal":{"name":"Langmuir","volume":"50 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143470456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-21DOI: 10.1021/acs.langmuir.4c04869
Li Zhang, Kaihui Liao, Jialu Liu, Peng Yang, Xiaojia Chen, Zhuo Zhong, Jie Li, Haihua Yang, Yanan Li, You-Nian Liu
Developing efficient photoanodes for photoelectrochemical (PEC) water splitting is crucial for solar-to-hydrogen energy conversion. Monocrystalline silicon, as a photoelectrode material, has limitations of high surface reflectivity, easy formation of oxide passivation, and instability in aqueous solutions. Herein, flower cluster CoSe2 and lamellar WO3 obtained via the solvothermal method are coated onto the surface of textured silicon by chemical bath deposition to prepare a multiheterojunction structured photoanode. The as-prepared CoSe2/WO3@Si-9 photoelectrode exhibits a desirable photocurrent of 10.1 mA cm–2 at 1.23 VRHE under simulated solar irradiation (AM 1.5G, 100 mW cm–2) in comparison to WO3@Si (0.49 mA cm–2) and CoSe2@Si (1.56 mA cm–2) and excellent stability over 10 h. The improved PEC hydrogen evolution performance comes from the synergistic effect of the multiple heterojunctions of CoSe2/WO3@Si composites. The synergistic effect can improve the separation efficiency of photogenerated electron-hole pairs while maintaining strong redox capability. The CoSe2/WO3@Si-9 photoanode exhibits a high photocurrent density and stability, making it a promising candidate for practical applications.
{"title":"Construction of CoSe2/WO3@Si Multiheterojunctions for Efficient Photoelectrochemical Water Splitting","authors":"Li Zhang, Kaihui Liao, Jialu Liu, Peng Yang, Xiaojia Chen, Zhuo Zhong, Jie Li, Haihua Yang, Yanan Li, You-Nian Liu","doi":"10.1021/acs.langmuir.4c04869","DOIUrl":"https://doi.org/10.1021/acs.langmuir.4c04869","url":null,"abstract":"Developing efficient photoanodes for photoelectrochemical (PEC) water splitting is crucial for solar-to-hydrogen energy conversion. Monocrystalline silicon, as a photoelectrode material, has limitations of high surface reflectivity, easy formation of oxide passivation, and instability in aqueous solutions. Herein, flower cluster CoSe<sub>2</sub> and lamellar WO<sub>3</sub> obtained via the solvothermal method are coated onto the surface of textured silicon by chemical bath deposition to prepare a multiheterojunction structured photoanode. The as-prepared CoSe<sub>2</sub>/WO<sub>3</sub>@Si-9 photoelectrode exhibits a desirable photocurrent of 10.1 mA cm<sup>–2</sup> at 1.23 V<sub>RHE</sub> under simulated solar irradiation (AM 1.5G, 100 mW cm<sup>–2</sup>) in comparison to WO<sub>3</sub>@Si (0.49 mA cm<sup>–2</sup>) and CoSe<sub>2</sub>@Si (1.56 mA cm<sup>–2</sup>) and excellent stability over 10 h. The improved PEC hydrogen evolution performance comes from the synergistic effect of the multiple heterojunctions of CoSe<sub>2</sub>/WO<sub>3</sub>@Si composites. The synergistic effect can improve the separation efficiency of photogenerated electron-hole pairs while maintaining strong redox capability. The CoSe<sub>2</sub>/WO<sub>3</sub>@Si-9 photoanode exhibits a high photocurrent density and stability, making it a promising candidate for practical applications.","PeriodicalId":50,"journal":{"name":"Langmuir","volume":"21 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143470547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-21DOI: 10.1021/acs.langmuir.4c03783
Ha Eun David Kang, Maxime Costalonga, Bert Vandereydt, Kripa K. Varanasi
Biofouling, commonly referred to as the unwanted deposition of cells on wetted solids, is a serious operational and environmental issue in many underwater and biomedical applications. Over the past decade, lubricant-impregnated surfaces (LIS) arose as a potential solution to prevent fouling, owing to their unique layer of lubricant masking the solid from the outer environment, thereby preventing biofouling. However, living microorganisms alter their environment by reproducing and secreting biomolecules, which can threaten the stability of such coatings over time. In this paper, we show that secretion of biomolecules from aquatic cells and subsequent changes in the interfacial tension of the surrounding media can trigger dewetting of the lubricant, ultimately exposing the surface to the outer solution and therefore becoming prone to fouling. By observing LIS immersed in Nannochloropsis oculata algae solutions at various stages of population growth, we establish a correlation between the decrease in interfacial tension and wetting states of the surface. We also visualize dewetting of the lubricant through confocal imaging performed in situ. Finally, we establish a diagram providing fundamental insights to design sturdy LIS circumventing such dewetting, therefore ensuring long-term protection against biofouling upon extended immersion in living cell solutions.
{"title":"Design of Antibiofouling Lubricant-Impregnated Surfaces Robust to Cell-Growth-Induced Instability","authors":"Ha Eun David Kang, Maxime Costalonga, Bert Vandereydt, Kripa K. Varanasi","doi":"10.1021/acs.langmuir.4c03783","DOIUrl":"https://doi.org/10.1021/acs.langmuir.4c03783","url":null,"abstract":"Biofouling, commonly referred to as the unwanted deposition of cells on wetted solids, is a serious operational and environmental issue in many underwater and biomedical applications. Over the past decade, lubricant-impregnated surfaces (LIS) arose as a potential solution to prevent fouling, owing to their unique layer of lubricant masking the solid from the outer environment, thereby preventing biofouling. However, living microorganisms alter their environment by reproducing and secreting biomolecules, which can threaten the stability of such coatings over time. In this paper, we show that secretion of biomolecules from aquatic cells and subsequent changes in the interfacial tension of the surrounding media can trigger dewetting of the lubricant, ultimately exposing the surface to the outer solution and therefore becoming prone to fouling. By observing LIS immersed in <i>Nannochloropsis oculata</i> algae solutions at various stages of population growth, we establish a correlation between the decrease in interfacial tension and wetting states of the surface. We also visualize dewetting of the lubricant through confocal imaging performed in situ. Finally, we establish a diagram providing fundamental insights to design sturdy LIS circumventing such dewetting, therefore ensuring long-term protection against biofouling upon extended immersion in living cell solutions.","PeriodicalId":50,"journal":{"name":"Langmuir","volume":"78 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143470449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Modulating the intrinsic activity of heterogeneous catalysts at the atomic level is an effective strategy to improve the low-temperature CO-SCR (selective catalytic reduction) reaction activity and N2 selectivity, but it remains challenging by the experiment. In this paper, a single-atom-loaded surface generation strategy is developed to construct single-atom catalysts by density functional theory analysis, which will effectively reduce the reaction energy barriers in CO-SCR reaction. Specifically, the reaction of NO reduction by CO before and after Ni adsorption was thoroughly investigated and the reactivity was evaluated by using the CeO2 (1 1 1) surface as a carrier, with the application of density functional theory, electronic structure analysis, and transition state theory. The loading of Ni increases the energy barrier for the generation of N2O on the CeO2 (1 1 1) surface by 1.498 eV and decreases the energy barrier for the generation of N2 by 1.864 eV. This indicates that the adsorption of Ni inhibits the generation of N2O and promotes the generation of N2. After thermodynamics and kinetics analysis, the pathway of CeO2 (1 1 1)-Ot-Ni via O atoms filling O vacancies to generate N2 is a spontaneous unidirectional reaction when no nonvolumetric work is done at constant temperature and pressure. Theoretical calculations show that the modification of isolated Ni atoms on CeO2 induces electronic coupling and redistribution, which leads to the activation of neighboring O sites around Ni atoms. This study provides the strategy mechanism to enhance the activity and N2 selectivity of the low-temperature CO-SCR reaction at the atomic level and provides theoretical guidance for the theory of novel catalysts for synergistic removal of NO and CO.
在原子水平上调控异相催化剂的内在活性是提高低温 CO-SCR（选择性催化还原）反应活性和 N2 选择性的有效策略，但在实验中仍面临挑战。本文通过密度泛函理论分析，提出了一种单原子负载表面生成策略，构建单原子催化剂，从而有效降低 CO-SCR 反应中的反应能垒。具体而言，应用密度泛函理论、电子结构分析和过渡态理论，以 CeO2 (1 1 1) 表面为载体，深入研究了吸附 Ni 前后 CO 还原 NO 的反应，并评估了反应活性。镍的负载使 CeO2 (1 1 1) 表面生成 N2O 的能垒增加了 1.498 eV，生成 N2 的能垒降低了 1.864 eV。这表明镍的吸附抑制了 N2O 的生成，促进了 N2 的生成。经过热力学和动力学分析，在恒温恒压下，当不做非体积功时，CeO2 (1 1 1)-Ot-Ni 通过 O 原子填充 O 空位生成 N2 的途径是一个自发的单向反应。理论计算表明，CeO2 上孤立镍原子的修饰会引起电子耦合和再分布，从而导致镍原子周围邻近 O 位点的活化。这项研究从原子水平上提供了提高低温 CO-SCR 反应活性和 N2 选择性的策略机制，并为协同去除 NO 和 CO 的新型催化剂理论提供了理论指导。
{"title":"Mechanisms for Modifying the Electronic and Spatial Distribution of the Single-Atom Ni/CeO2 Surface to Enhance CO-SCR Reactivity: Density Functional Theory Study","authors":"Mingtao Yang, Jiancheng Yang, Long Chen, Shuhao Li, Peng Zhao, Boxiong Shen","doi":"10.1021/acs.langmuir.4c04544","DOIUrl":"https://doi.org/10.1021/acs.langmuir.4c04544","url":null,"abstract":"Modulating the intrinsic activity of heterogeneous catalysts at the atomic level is an effective strategy to improve the low-temperature CO-SCR (selective catalytic reduction) reaction activity and N<sub>2</sub> selectivity, but it remains challenging by the experiment. In this paper, a single-atom-loaded surface generation strategy is developed to construct single-atom catalysts by density functional theory analysis, which will effectively reduce the reaction energy barriers in CO-SCR reaction. Specifically, the reaction of NO reduction by CO before and after Ni adsorption was thoroughly investigated and the reactivity was evaluated by using the CeO<sub>2</sub> (1 1 1) surface as a carrier, with the application of density functional theory, electronic structure analysis, and transition state theory. The loading of Ni increases the energy barrier for the generation of N<sub>2</sub>O on the CeO<sub>2</sub> (1 1 1) surface by 1.498 eV and decreases the energy barrier for the generation of N<sub>2</sub> by 1.864 eV. This indicates that the adsorption of Ni inhibits the generation of N<sub>2</sub>O and promotes the generation of N<sub>2</sub>. After thermodynamics and kinetics analysis, the pathway of CeO<sub>2</sub> (1 1 1)-O<sub>t</sub>-Ni via O atoms filling O vacancies to generate N<sub>2</sub> is a spontaneous unidirectional reaction when no nonvolumetric work is done at constant temperature and pressure. Theoretical calculations show that the modification of isolated Ni atoms on CeO<sub>2</sub> induces electronic coupling and redistribution, which leads to the activation of neighboring O sites around Ni atoms. This study provides the strategy mechanism to enhance the activity and N<sub>2</sub> selectivity of the low-temperature CO-SCR reaction at the atomic level and provides theoretical guidance for the theory of novel catalysts for synergistic removal of NO and CO.","PeriodicalId":50,"journal":{"name":"Langmuir","volume":"1 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143470544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-20DOI: 10.1021/acs.langmuir.4c03853
Enyi Chi, Haiying Huang, Fajun Zhang, Tianbai He
Self-assembly of hard platelet colloids into liquid crystalline phases is typically driven by entropy, making them less sensitive to temperature changes. However, soft interaction potentials often exist in real colloidal systems, which can lead to temperature-sensitive phase transitions. Despite significant progress in understanding phase behavior in the past 2 decades, studies on temperature-dependent phase behavior remain rare, and there is limited knowledge about how soft interactions influence phase transitions upon temperature changes. In this work, we investigated a platelet colloid system in isotropic and nematic phases using small- and wide-angle X-ray scattering techniques (SAXS/WAXS) and polarized optical microscopy (POM). The system consisted of polystyrene-block-poly(l-lactide) (PS-b-PLLA) block copolymer single crystals (BCSCs) with varying sizes dispersed in p-xylene. These crystals were truncated lozenge-shaped with effective diameters of 500 and 1000 nm and a uniform dry thickness of 18.0 nm. The ordering behaviors of BCSC500 in the isotropic phase and BCSC1000 in the N phase were monitored through SAXS/WAXS during heating, quenching, self-seeding, crystal growth, and final quenching. Enhanced ordering, specifically face-to-face correlation, was observed during heating prior to crystal melting. For BCSC500, ordering emerged at 105 °C during heating. In the case of BCSC1000 in the N phase, ordering was enhanced with increased heating and reached up to the ninth order of correlation peaks, indicating the formation of lamellar domains within the N phase. After seeding and crystal growth, both systems exhibited ordering. However, during the final cooling to room temperature, ordering disappeared for BCSC500 but persisted for BCSC1000. POM observations revealed that for both systems, initial heating resulted in a decrease in overall brightness; however, enhanced nematic domains or tactoids emerged prior to melting. Subsequent thermal treatments did not induce noticeable changes in the observed order. While both techniques revealed increased order, discrepancies were noted. SAXS indicated intensified short-range correlations, while POM showed the formation of local nematic domains or tactoids. We propose three distinct ordering regimes to reconcile these observations: large-scale nematic order, enhanced short-range order, and short-range clusters. We attributed the temperature-enhanced ordering phenomenon to lateral interactions between the BCSCs, annealing, and memory effects during melting and crystallization.
{"title":"Temperature-Enhanced Ordering in Plate-like Semicrystalline Block Copolymer Single-Crystal Suspensions Studied by Real-Time SAXS/WAXS","authors":"Enyi Chi, Haiying Huang, Fajun Zhang, Tianbai He","doi":"10.1021/acs.langmuir.4c03853","DOIUrl":"https://doi.org/10.1021/acs.langmuir.4c03853","url":null,"abstract":"Self-assembly of hard platelet colloids into liquid crystalline phases is typically driven by entropy, making them less sensitive to temperature changes. However, soft interaction potentials often exist in real colloidal systems, which can lead to temperature-sensitive phase transitions. Despite significant progress in understanding phase behavior in the past 2 decades, studies on temperature-dependent phase behavior remain rare, and there is limited knowledge about how soft interactions influence phase transitions upon temperature changes. In this work, we investigated a platelet colloid system in isotropic and nematic phases using small- and wide-angle X-ray scattering techniques (SAXS/WAXS) and polarized optical microscopy (POM). The system consisted of polystyrene-<i>block</i>-poly(<span>l</span>-lactide) (PS-<i>b</i>-PLLA) block copolymer single crystals (BCSCs) with varying sizes dispersed in <i>p</i>-xylene. These crystals were truncated lozenge-shaped with effective diameters of 500 and 1000 nm and a uniform dry thickness of 18.0 nm. The ordering behaviors of BCSC500 in the isotropic phase and BCSC1000 in the N phase were monitored through SAXS/WAXS during heating, quenching, self-seeding, crystal growth, and final quenching. Enhanced ordering, specifically face-to-face correlation, was observed during heating prior to crystal melting. For BCSC500, ordering emerged at 105 °C during heating. In the case of BCSC1000 in the N phase, ordering was enhanced with increased heating and reached up to the ninth order of correlation peaks, indicating the formation of lamellar domains within the N phase. After seeding and crystal growth, both systems exhibited ordering. However, during the final cooling to room temperature, ordering disappeared for BCSC500 but persisted for BCSC1000. POM observations revealed that for both systems, initial heating resulted in a decrease in overall brightness; however, enhanced nematic domains or tactoids emerged prior to melting. Subsequent thermal treatments did not induce noticeable changes in the observed order. While both techniques revealed increased order, discrepancies were noted. SAXS indicated intensified short-range correlations, while POM showed the formation of local nematic domains or tactoids. We propose three distinct ordering regimes to reconcile these observations: large-scale nematic order, enhanced short-range order, and short-range clusters. We attributed the temperature-enhanced ordering phenomenon to lateral interactions between the BCSCs, annealing, and memory effects during melting and crystallization.","PeriodicalId":50,"journal":{"name":"Langmuir","volume":"49 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143463061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Droplet electrodispersion is a fundamental phenomenon in various fields, such as electric demulsification, electrospray, and microfluidic manipulation. Electric-magnetic coupling technology, as an emerging noncontact method, shows substantial potential in modulating droplet electrohydrodynamics, yet the influence characteristics and mechanisms of coupled magnetic fields on droplet electrodispersion remain poorly understood. To address this gap, we conducted a detailed molecular dynamics simulation comparing the breakup dynamics of salt-containing droplets under a single electric field versus an electric-magnetic coupling field. Our results demonstrate that salty droplets in the electric-magnetic coupling field exhibit longer breakup response times and greater stretching deformation. This behavior is attributed to changes in ion migration speed and enrichment regions due to additional Lorentz forces. Furthermore, this effect of coupling field is observed only for ion numbers Nion > 0, with a marked attenuation at higher concentrations (Nion = 200), which is related to the hydration effect enhanced by magnetic field. When the electric capillary number Ca ranges from 0.88 to 3.91, the critical value triggering a shift in the breakup mode is enhanced in the coupling field. However, this effect diminishes as Ca approaches 8.8, at which point the coupled field no longer inhibits breakup. Additionally, as the dimensionless electric field frequency f* increases from 0.21 to 4.19, the ion migration trajectories become shorter and less able to accumulate at the interface, thereby limiting the effectiveness of the coupling field. Our study advances the fundamental understanding of salt-containing droplet breakup dynamics under an electric-magnetic coupling field and provides novel insights for controlling and suppressing electrodispersion in related technologies.
{"title":"Optimizing and Regulating Electric-Induced Breakup of Salt-Containing Droplets through Magnetic Field Coupling: Insights from Molecular Dynamics Simulations.","authors":"Mofan Li, Donghai Yang, Qing Li, Yuejiu Liang, Chaohui Chen, Limin He","doi":"10.1021/acs.langmuir.4c04208","DOIUrl":"https://doi.org/10.1021/acs.langmuir.4c04208","url":null,"abstract":"<p><p>Droplet electrodispersion is a fundamental phenomenon in various fields, such as electric demulsification, electrospray, and microfluidic manipulation. Electric-magnetic coupling technology, as an emerging noncontact method, shows substantial potential in modulating droplet electrohydrodynamics, yet the influence characteristics and mechanisms of coupled magnetic fields on droplet electrodispersion remain poorly understood. To address this gap, we conducted a detailed molecular dynamics simulation comparing the breakup dynamics of salt-containing droplets under a single electric field versus an electric-magnetic coupling field. Our results demonstrate that salty droplets in the electric-magnetic coupling field exhibit longer breakup response times and greater stretching deformation. This behavior is attributed to changes in ion migration speed and enrichment regions due to additional Lorentz forces. Furthermore, this effect of coupling field is observed only for ion numbers <i>N</i><sub>ion</sub> > 0, with a marked attenuation at higher concentrations (<i>N</i><sub>ion</sub> = 200), which is related to the hydration effect enhanced by magnetic field. When the electric capillary number Ca ranges from 0.88 to 3.91, the critical value triggering a shift in the breakup mode is enhanced in the coupling field. However, this effect diminishes as Ca approaches 8.8, at which point the coupled field no longer inhibits breakup. Additionally, as the dimensionless electric field frequency <i>f</i>* increases from 0.21 to 4.19, the ion migration trajectories become shorter and less able to accumulate at the interface, thereby limiting the effectiveness of the coupling field. Our study advances the fundamental understanding of salt-containing droplet breakup dynamics under an electric-magnetic coupling field and provides novel insights for controlling and suppressing electrodispersion in related technologies.</p>","PeriodicalId":50,"journal":{"name":"Langmuir","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143456272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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