Lishi Zhou, Haotian Wen, I. Kuschnerus, Shery L. Y. Chang
Morphologies of nanoparticles and aggregates play an important role in their properties for a range of applications. In particular, significant synthesis efforts have been directed toward controlling nanoparticle morphology and aggregation behavior in biomedical applications, as their size and shape have a significant impact on cellular uptake. Among several techniques for morphological characterization, transmission electron microscopy (TEM) can provide direct and accurate characterization of nanoparticle/aggregate morphology details. Nevertheless, manually analyzing a large number of TEM images is still a laborious process. Hence, there has been a surge of interest in employing machine learning methods to analyze nanoparticle size and shape. In order to achieve accurate nanoparticle analysis using machine learning methods, reliable and automated nanoparticle segmentation from TEM images is critical, especially when the nanoparticle image contrast is weak and the background is complex. These challenges are particularly pertinent in biomedical applications. In this work, we demonstrate an efficient, robust, and automated nanoparticle image segmentation method suitable for subsequent machine learning analysis. Our method is robust for noisy, low-electron-dose cryo-TEM images and for TEM cell images with complex, strong-contrast background features. Moreover, our method does not require any a priori training datasets, making it efficient and general. The ability to automatically, reliably, and efficiently segment nanoparticle/aggregate images is critical for advancing precise particle/aggregate control in biomedical applications.
纳米粒子和聚集体的形态对其在一系列应用中的特性起着重要作用。特别是在生物医学应用中，由于纳米粒子的大小和形状对细胞吸收有重要影响，因此人们一直致力于控制纳米粒子的形态和聚集行为。在多种形态表征技术中，透射电子显微镜（TEM）可直接准确地表征纳米粒子/聚集体的形态细节。然而，手动分析大量 TEM 图像仍然是一个费力的过程。因此，人们对采用机器学习方法来分析纳米粒子的尺寸和形状产生了浓厚的兴趣。为了利用机器学习方法实现准确的纳米粒子分析，从 TEM 图像中进行可靠的自动纳米粒子分割至关重要，尤其是在纳米粒子图像对比度较弱、背景复杂的情况下。这些挑战在生物医学应用中尤为突出。在这项工作中，我们展示了一种高效、稳健和自动化的纳米粒子图像分割方法，适合后续的机器学习分析。我们的方法对于有噪声、低电子剂量的低温 TEM 图像以及具有复杂、强对比背景特征的 TEM 细胞图像都很稳健。此外，我们的方法不需要任何先验训练数据集，因此既高效又通用。自动、可靠、高效地分割纳米粒子/聚集体图像的能力对于推进生物医学应用中的粒子/聚集体精确控制至关重要。
{"title":"Efficientand Robust Automated Segmentation of Nanoparticles and Aggregates from Transmission Electron Microscopy Images with Highly Complex Backgrounds","authors":"Lishi Zhou, Haotian Wen, I. Kuschnerus, Shery L. Y. Chang","doi":"10.3390/nano14141169","DOIUrl":"https://doi.org/10.3390/nano14141169","url":null,"abstract":"Morphologies of nanoparticles and aggregates play an important role in their properties for a range of applications. In particular, significant synthesis efforts have been directed toward controlling nanoparticle morphology and aggregation behavior in biomedical applications, as their size and shape have a significant impact on cellular uptake. Among several techniques for morphological characterization, transmission electron microscopy (TEM) can provide direct and accurate characterization of nanoparticle/aggregate morphology details. Nevertheless, manually analyzing a large number of TEM images is still a laborious process. Hence, there has been a surge of interest in employing machine learning methods to analyze nanoparticle size and shape. In order to achieve accurate nanoparticle analysis using machine learning methods, reliable and automated nanoparticle segmentation from TEM images is critical, especially when the nanoparticle image contrast is weak and the background is complex. These challenges are particularly pertinent in biomedical applications. In this work, we demonstrate an efficient, robust, and automated nanoparticle image segmentation method suitable for subsequent machine learning analysis. Our method is robust for noisy, low-electron-dose cryo-TEM images and for TEM cell images with complex, strong-contrast background features. Moreover, our method does not require any a priori training datasets, making it efficient and general. The ability to automatically, reliably, and efficiently segment nanoparticle/aggregate images is critical for advancing precise particle/aggregate control in biomedical applications.","PeriodicalId":508599,"journal":{"name":"Nanomaterials","volume":"117 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141666079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Do Hyung Han, Hyunsu Park, T. Goto, S. Cho, Yeongjun Seo, Yoshifumi Kondo, H. Nishida, Tohru Sekino
Lepidocrocite-type layered sodium titanate (NaxH2−xTi2O5) is widely used in environmental remediation because of its large specific surface area, formed by anisotropic crystal growth, and its ability to store and exchange cations between layers. Additionally, peroxo-titanate nanotubes (PTNTs), which are tubular titanates with peroxy groups, exhibit visible-light absorption capabilities, rendering them suitable for photocatalytic applications under visible light irradiation. However, because of cation exchange reactions, the Na+ concentration and pH of the solution can fluctuate under aqueous conditions, affecting the photocatalytic performance of the PTNTs. Herein, we evaluated the impact of cation exchange reactions on the photocatalytic degradation of Rhodamine B (Rh B) by PTNTs at controlled Na+ ratios. The observed pH of Rh B solutions increases due to the cation exchange reaction with Na+ and H3O+, leading to the formation of zwitter-ionic Rh B molecules, eventually weakening their adsorption and photodegradation performance. Moreover, the results indicate that inhibiting the pH increase of the Rh B solution can prevent the weakening of both the adsorption and photodegradation performance of PTNTs. This study highlights the significance of regulating the sodium ion content in layered titanate materials, emphasizing their importance in optimizing these materials’ photocatalytic efficacy for environmental purification applications.
{"title":"Effects of Cation Exchange in Rhodamine B Photocatalytic Degradation Using Peroxo-Titanate Nanotubes","authors":"Do Hyung Han, Hyunsu Park, T. Goto, S. Cho, Yeongjun Seo, Yoshifumi Kondo, H. Nishida, Tohru Sekino","doi":"10.3390/nano14141170","DOIUrl":"https://doi.org/10.3390/nano14141170","url":null,"abstract":"Lepidocrocite-type layered sodium titanate (NaxH2−xTi2O5) is widely used in environmental remediation because of its large specific surface area, formed by anisotropic crystal growth, and its ability to store and exchange cations between layers. Additionally, peroxo-titanate nanotubes (PTNTs), which are tubular titanates with peroxy groups, exhibit visible-light absorption capabilities, rendering them suitable for photocatalytic applications under visible light irradiation. However, because of cation exchange reactions, the Na+ concentration and pH of the solution can fluctuate under aqueous conditions, affecting the photocatalytic performance of the PTNTs. Herein, we evaluated the impact of cation exchange reactions on the photocatalytic degradation of Rhodamine B (Rh B) by PTNTs at controlled Na+ ratios. The observed pH of Rh B solutions increases due to the cation exchange reaction with Na+ and H3O+, leading to the formation of zwitter-ionic Rh B molecules, eventually weakening their adsorption and photodegradation performance. Moreover, the results indicate that inhibiting the pH increase of the Rh B solution can prevent the weakening of both the adsorption and photodegradation performance of PTNTs. This study highlights the significance of regulating the sodium ion content in layered titanate materials, emphasizing their importance in optimizing these materials’ photocatalytic efficacy for environmental purification applications.","PeriodicalId":508599,"journal":{"name":"Nanomaterials","volume":"35 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141663527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hydrogen is now recognized as the primary alternative to fossil fuels due to its renewable, safe, high-energy density and environmentally friendly properties. Efficient hydrogen production through water splitting has laid the foundation for sustainable energy technologies. However, when hydrogen production is scaled up to industrial levels, operating at high current densities introduces unique challenges. It is necessary to design advanced electrocatalysts for hydrogen evolution reactions (HERs) under high current densities. This review will briefly introduce the challenges posed by high current densities on electrocatalysts, including catalytic activity, mass diffusion, and catalyst stability. In an attempt to address these issues, various electrocatalyst design strategies are summarized in detail. In the end, our insights into future challenges for efficient large-scale industrial hydrogen production from water splitting are presented. This review is expected to guide the rational design of efficient high-current density water electrolysis electrocatalysts and promote the research progress of sustainable energy.
{"title":"Design Strategies of Hydrogen Evolution Reaction Nano Electrocatalysts for High Current Density Water Splitting","authors":"Bao Zang, Xianya Liu, Chen Gu, Jianmei Chen, Longlu Wang, Weihao Zheng","doi":"10.3390/nano14141172","DOIUrl":"https://doi.org/10.3390/nano14141172","url":null,"abstract":"Hydrogen is now recognized as the primary alternative to fossil fuels due to its renewable, safe, high-energy density and environmentally friendly properties. Efficient hydrogen production through water splitting has laid the foundation for sustainable energy technologies. However, when hydrogen production is scaled up to industrial levels, operating at high current densities introduces unique challenges. It is necessary to design advanced electrocatalysts for hydrogen evolution reactions (HERs) under high current densities. This review will briefly introduce the challenges posed by high current densities on electrocatalysts, including catalytic activity, mass diffusion, and catalyst stability. In an attempt to address these issues, various electrocatalyst design strategies are summarized in detail. In the end, our insights into future challenges for efficient large-scale industrial hydrogen production from water splitting are presented. This review is expected to guide the rational design of efficient high-current density water electrolysis electrocatalysts and promote the research progress of sustainable energy.","PeriodicalId":508599,"journal":{"name":"Nanomaterials","volume":"23 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141664858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kunting Cai, Weibin Chen, Yinji Wan, H. Chu, Xiao Hai, Ruqiang Zou
Refining synthesis strategies for metal–organic framework (MOF)-based catalysts to improve their performance and stability in an oxygen evolution reaction (OER) is a big challenge. In this study, a series of nanostructured electrocatalysts were synthesized through a solvothermal method by growing MOFs and metal–triazolates (METs) on nickel foam (NF) substrates (named MET-M/NF, M = Fe, Co, Cu), and these electrocatalysts could be used directly as OER self-supporting electrodes. Among these electrocatalysts, MET-Fe/NF exhibited the best OER performance, requiring only an overpotential of 122 mV at a current density of 10 mA cm−2 and showing remarkable stability over 15 h. The experimental results uncovered that MET-Fe/NF underwent an in situ structural reconstruction, resulting in the formation of numerous iron/nickel (oxy)hydroxides with high OER activity. Furthermore, in a two-electrode water-splitting setup, MET-Fe/NF only required 1.463 V to achieve a current density of 10 mA cm−2. Highlighting its potential for practical applications. This work provides insight into the design and development of efficient MOF-based OER catalysts.
改进基于金属有机框架（MOF）的催化剂的合成策略，以提高其在氧进化反应（OER）中的性能和稳定性，是一项巨大的挑战。本研究在泡沫镍（NF）基底（命名为 MET-M/NF，M = Fe、Co、Cu）上生长 MOFs 和金属三唑酸盐 (METs)，通过溶解热法合成了一系列纳米结构的电催化剂，这些电催化剂可直接用作 OER 自支撑电极。实验结果表明，MET-Fe/NF 发生了原位结构重构，形成了大量具有高 OER 活性的铁/镍（氧）氢氧化物。此外，在双电极分水装置中，MET-Fe/NF 只需要 1.463 V 就能达到 10 mA cm-2 的电流密度。这凸显了它在实际应用中的潜力。这项工作为设计和开发基于 MOF 的高效 OER 催化剂提供了启示。
{"title":"Self-Reconstructed Metal–Organic Framework-Based Hybrid Electrocatalysts for Efficient Oxygen Evolution","authors":"Kunting Cai, Weibin Chen, Yinji Wan, H. Chu, Xiao Hai, Ruqiang Zou","doi":"10.3390/nano14141168","DOIUrl":"https://doi.org/10.3390/nano14141168","url":null,"abstract":"Refining synthesis strategies for metal–organic framework (MOF)-based catalysts to improve their performance and stability in an oxygen evolution reaction (OER) is a big challenge. In this study, a series of nanostructured electrocatalysts were synthesized through a solvothermal method by growing MOFs and metal–triazolates (METs) on nickel foam (NF) substrates (named MET-M/NF, M = Fe, Co, Cu), and these electrocatalysts could be used directly as OER self-supporting electrodes. Among these electrocatalysts, MET-Fe/NF exhibited the best OER performance, requiring only an overpotential of 122 mV at a current density of 10 mA cm−2 and showing remarkable stability over 15 h. The experimental results uncovered that MET-Fe/NF underwent an in situ structural reconstruction, resulting in the formation of numerous iron/nickel (oxy)hydroxides with high OER activity. Furthermore, in a two-electrode water-splitting setup, MET-Fe/NF only required 1.463 V to achieve a current density of 10 mA cm−2. Highlighting its potential for practical applications. This work provides insight into the design and development of efficient MOF-based OER catalysts.","PeriodicalId":508599,"journal":{"name":"Nanomaterials","volume":"67 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141664562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lithium metal batteries (LMBs) are anticipated to meet the demand for high energy density, but the growth of lithium dendrites seriously hinders its practical application. Herein, we constructed a kind of composite separator (ZIF-90@PP) consisting of zeolite imidazole framework-90 (ZIF-90) and polypropylene (PP) to promote the uniform deposition of Li+ and inhibit the growth of lithium dendrites. The aldehyde groups interacting with TFSI− and the nitrogen-containing negative groups attracting Li+ of ZIF-90 can facilitate the dissociation of LiTFSI to release more Li+, thus alleviating the influence of space charge near the electrode surface and accelerating the transfer of Li+. Not only does the excellent electrolyte wettability of ZIF-90 enhance the electrolyte retention capacity of the separator, but the orderly nano-channels in ZIF-90 also restrict the free migration of anions and homogenize the distribution of Li+. Consequently, the functional separator achieves a long-term stable Li plating/stripping cycling for over 780 h at 2 mA cm−2. Moreover, an impressive average coulombic efficiency of 98.67% at 0.5 C after 300 cycles is realized by Li || LFP full cells based on ZIF-90@PP with a capacity retention rate of 71.22%. The high-rate and long cycling performance of the modified Li || LFP cells further demonstrates the advantages of the ZIF-90@PP composite separator.
{"title":"Long-Term Stable Cycling of Dendrite-Free Lithium Metal Batteries Using ZIF-90@PP Composite Separator","authors":"Shuilan Lyu, Xin Zhang, Sheng Huang, Shuanjin Wang, M. Xiao, Dongmei Han, Yuezhong Meng","doi":"10.3390/nano14110975","DOIUrl":"https://doi.org/10.3390/nano14110975","url":null,"abstract":"Lithium metal batteries (LMBs) are anticipated to meet the demand for high energy density, but the growth of lithium dendrites seriously hinders its practical application. Herein, we constructed a kind of composite separator (ZIF-90@PP) consisting of zeolite imidazole framework-90 (ZIF-90) and polypropylene (PP) to promote the uniform deposition of Li+ and inhibit the growth of lithium dendrites. The aldehyde groups interacting with TFSI− and the nitrogen-containing negative groups attracting Li+ of ZIF-90 can facilitate the dissociation of LiTFSI to release more Li+, thus alleviating the influence of space charge near the electrode surface and accelerating the transfer of Li+. Not only does the excellent electrolyte wettability of ZIF-90 enhance the electrolyte retention capacity of the separator, but the orderly nano-channels in ZIF-90 also restrict the free migration of anions and homogenize the distribution of Li+. Consequently, the functional separator achieves a long-term stable Li plating/stripping cycling for over 780 h at 2 mA cm−2. Moreover, an impressive average coulombic efficiency of 98.67% at 0.5 C after 300 cycles is realized by Li || LFP full cells based on ZIF-90@PP with a capacity retention rate of 71.22%. The high-rate and long cycling performance of the modified Li || LFP cells further demonstrates the advantages of the ZIF-90@PP composite separator.","PeriodicalId":508599,"journal":{"name":"Nanomaterials","volume":"71 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141268349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Enas Ismail, Abubaker Mohamed, Amir Elzwawy, E. Maboza, M. Dhlamini, R. Adam
A comparative study was applied to investigate the potential of Callistemon citrinus (bottlebrush) flower extract (BBE) and Punica granatum (pomegranate) peel extracts (PPE) for the sustainable synthesis of the silver nanoparticles, Ag-BBE and Ag-PPE, respectively. The synthesis process of Ag NPs using the selected extracts was applied under optimized conditions. Hence, the effect of the selected plant’s type on the different characteristics of the synthesized green Ag NPs was investigated. The UV-Vis spectroscopy revealed the presence of the characteristic silver peaks at 419 and 433 nm of the Ag-BBE and Ag-PPE, respectively. The XRD spectra reported the fcc phase formation of Ag NPs. The TEM results highlighted the morphological features of the synthesized Ag NPs. with a size range of 20–70 nm, and with 10–30 nm for Ag-BBE and Ag-PPE, correspondingly. The Raman spectra revealed characteristic silver bands in the Ag-PPE and reflected some bands related to the natural extract in the Ag-BBE sample. The antimicrobial activity and statistical analysis investigation were conducted against four selected oral pathogens (Staphylococcus aureus (SA), Candida albicans (CA), Staphylococcus epidermidis (S. epi), and Enterococcus faecalis (EF)). Both tested extracts, BBE, and PPE, revealed potential effectivity as reducing and capping agents for Ag NP green synthesis. However, the synthesized NPs demonstrated different features, depending on the used extract, reflecting the influence of the plant’s biomolecules on the nanoparticles’ properties.
{"title":"Comparative Study of Callistemon citrinus (Bottlebrush) and Punica granatum (Pomegranate) Extracts for Sustainable Synthesis of Silver Nanoparticles and Their Oral Antimicrobial Efficacy","authors":"Enas Ismail, Abubaker Mohamed, Amir Elzwawy, E. Maboza, M. Dhlamini, R. Adam","doi":"10.3390/nano14110974","DOIUrl":"https://doi.org/10.3390/nano14110974","url":null,"abstract":"A comparative study was applied to investigate the potential of Callistemon citrinus (bottlebrush) flower extract (BBE) and Punica granatum (pomegranate) peel extracts (PPE) for the sustainable synthesis of the silver nanoparticles, Ag-BBE and Ag-PPE, respectively. The synthesis process of Ag NPs using the selected extracts was applied under optimized conditions. Hence, the effect of the selected plant’s type on the different characteristics of the synthesized green Ag NPs was investigated. The UV-Vis spectroscopy revealed the presence of the characteristic silver peaks at 419 and 433 nm of the Ag-BBE and Ag-PPE, respectively. The XRD spectra reported the fcc phase formation of Ag NPs. The TEM results highlighted the morphological features of the synthesized Ag NPs. with a size range of 20–70 nm, and with 10–30 nm for Ag-BBE and Ag-PPE, correspondingly. The Raman spectra revealed characteristic silver bands in the Ag-PPE and reflected some bands related to the natural extract in the Ag-BBE sample. The antimicrobial activity and statistical analysis investigation were conducted against four selected oral pathogens (Staphylococcus aureus (SA), Candida albicans (CA), Staphylococcus epidermidis (S. epi), and Enterococcus faecalis (EF)). Both tested extracts, BBE, and PPE, revealed potential effectivity as reducing and capping agents for Ag NP green synthesis. However, the synthesized NPs demonstrated different features, depending on the used extract, reflecting the influence of the plant’s biomolecules on the nanoparticles’ properties.","PeriodicalId":508599,"journal":{"name":"Nanomaterials","volume":"80 17","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141268138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bhartendu Papnai, Ding-Rui Chen, Rapti Ghosh, Zhi-long Yen, Yu-Xiang Chen, Khalil Ur Rehman, Hsin-Yi Tiffany Chen, Ya-Ping Hsieh, Mario Hofmann
Two-dimensional (2D) materials promise advances in electronic devices beyond Moore’s scaling law through extended functionality, such as non-monotonic dependence of device parameters on input parameters. However, the robustness and performance of effects like negative differential resistance (NDR) and anti-ambipolar behavior have been limited in scale and robustness by relying on atomic defects and complex heterojunctions. In this paper, we introduce a novel device concept that utilizes the quantum capacitance of junctions between 2D materials and molecular layers. We realized a variable capacitance 2D molecular junction (vc2Dmj) diode through the scalable integration of graphene and single layers of stearic acid. The vc2Dmj exhibits NDR with a substantial peak-to-valley ratio even at room temperature and an active negative resistance region. The origin of this unique behavior was identified through thermoelectric measurements and ab initio calculations to be a hybridization effect between graphene and the molecular layer. The enhancement of device parameters through morphology optimization highlights the potential of our approach toward new functionalities that advance the landscape of future electronics.
二维（2D）材料通过扩展功能，如器件参数对输入参数的非单调依赖性，有望使电子器件的发展超越摩尔扩展定律。然而，由于依赖原子缺陷和复杂的异质结，负差分电阻（NDR）和反双极行为等效应的稳健性和性能在规模和稳健性方面受到了限制。在本文中，我们介绍了一种利用二维材料和分子层之间结点的量子电容的新型器件概念。我们通过对石墨烯和单层硬脂酸的可扩展集成，实现了可变电容二维分子结（vc2Dmj）二极管。vc2Dmj 即使在室温下也能表现出具有可观峰谷比的 NDR，并具有一个活跃的负阻区域。通过热电测量和 ab initio 计算，确定了这种独特行为的起源是石墨烯和分子层之间的杂化效应。通过形态优化提高器件参数，凸显了我们的方法在实现新功能方面的潜力，从而推动未来电子技术的发展。
{"title":"Harnessing Quantum Capacitance in 2D Material/Molecular Layer Junctions for Novel Electronic Device Functionality","authors":"Bhartendu Papnai, Ding-Rui Chen, Rapti Ghosh, Zhi-long Yen, Yu-Xiang Chen, Khalil Ur Rehman, Hsin-Yi Tiffany Chen, Ya-Ping Hsieh, Mario Hofmann","doi":"10.3390/nano14110972","DOIUrl":"https://doi.org/10.3390/nano14110972","url":null,"abstract":"Two-dimensional (2D) materials promise advances in electronic devices beyond Moore’s scaling law through extended functionality, such as non-monotonic dependence of device parameters on input parameters. However, the robustness and performance of effects like negative differential resistance (NDR) and anti-ambipolar behavior have been limited in scale and robustness by relying on atomic defects and complex heterojunctions. In this paper, we introduce a novel device concept that utilizes the quantum capacitance of junctions between 2D materials and molecular layers. We realized a variable capacitance 2D molecular junction (vc2Dmj) diode through the scalable integration of graphene and single layers of stearic acid. The vc2Dmj exhibits NDR with a substantial peak-to-valley ratio even at room temperature and an active negative resistance region. The origin of this unique behavior was identified through thermoelectric measurements and ab initio calculations to be a hybridization effect between graphene and the molecular layer. The enhancement of device parameters through morphology optimization highlights the potential of our approach toward new functionalities that advance the landscape of future electronics.","PeriodicalId":508599,"journal":{"name":"Nanomaterials","volume":"41 41","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141270109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pei Zhang, Yibo Zheng, L. Ren, Shaojun Li, Ming Feng, Qingfang Zhang, Rubin Qi, Zirui Qin, Jitao Zhang, Liying Jiang
The investigation of the fluorescence mechanism of carbon dots (CDs) has attracted significant attention, particularly the role of the oxygen-containing groups. Dual-CDs exhibiting blue and green emissions are synthesized from glucose via a simple ultrasonic treatment, and the oxidation degree of the CDs is softly modified through a slow natural oxidation approach, which is in stark contrast to that aggressively altering CDs’ surface configurations through chemical oxidation methods. It is interesting to find that the intensity of the blue fluorescence gradually increases, eventually becoming the dominant emission after prolonging the oxidation periods, with the quantum yield (QY) of the CDs being enhanced from ~0.61% to ~4.26%. Combining the microstructure characterizations, optical measurements, and ultrafiltration experiments, we hypothesize that the blue emission could be ascribed to the surface states induced by the C–O and C=O groups, while the green luminescence may originate from the deep energy levels associated with the O–C=O groups. The distinct emission states and energy distributions could result in the blue and the green luminescence exhibiting distinct excitation and emission behaviors. Our findings could provide new insights into the fluorescence mechanism of CDs.
{"title":"The Enhanced Photoluminescence Properties of Carbon Dots Derived from Glucose: The Effect of Natural Oxidation","authors":"Pei Zhang, Yibo Zheng, L. Ren, Shaojun Li, Ming Feng, Qingfang Zhang, Rubin Qi, Zirui Qin, Jitao Zhang, Liying Jiang","doi":"10.3390/nano14110970","DOIUrl":"https://doi.org/10.3390/nano14110970","url":null,"abstract":"The investigation of the fluorescence mechanism of carbon dots (CDs) has attracted significant attention, particularly the role of the oxygen-containing groups. Dual-CDs exhibiting blue and green emissions are synthesized from glucose via a simple ultrasonic treatment, and the oxidation degree of the CDs is softly modified through a slow natural oxidation approach, which is in stark contrast to that aggressively altering CDs’ surface configurations through chemical oxidation methods. It is interesting to find that the intensity of the blue fluorescence gradually increases, eventually becoming the dominant emission after prolonging the oxidation periods, with the quantum yield (QY) of the CDs being enhanced from ~0.61% to ~4.26%. Combining the microstructure characterizations, optical measurements, and ultrafiltration experiments, we hypothesize that the blue emission could be ascribed to the surface states induced by the C–O and C=O groups, while the green luminescence may originate from the deep energy levels associated with the O–C=O groups. The distinct emission states and energy distributions could result in the blue and the green luminescence exhibiting distinct excitation and emission behaviors. Our findings could provide new insights into the fluorescence mechanism of CDs.","PeriodicalId":508599,"journal":{"name":"Nanomaterials","volume":"33 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141272449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Using KOH-modified wheat straw as the precursor, wheat straw biochar was produced through carbonization at 500 °C. Subsequently, a synthetic material containing nano-zero-valent iron (nZVI) was prepared via liquid phase reduction (nZVI-WSPC). To enhance its properties, chitosan (CTS) was used by crosslinking to form the new adsorbent named CTS@nZVI-WSPC. The impact of CTS on parameters such as mass ratio, initial pH value, and adsorbent dosage on the adsorption efficiency of Cr(VI) in solution was investigated through one-factor experiments. Isotherm adsorption and thermodynamic analysis demonstrated that the adsorption of Cr(VI) by CTS@nZVI-WSPC conforms to the Langmuir model, with a maximum adsorption capacity of 147.93 mg/g, and the adsorption process is endothermic. Kinetic analysis revealed that the adsorption process follows a pseudo-second-order kinetic model. The adsorption mechanism, as elucidated by SEM, FTIR, XPS, and XRD, suggests that the process may involve multiple mechanisms, including pore adsorption, electrostatic adsorption, chemical reduction, and surface chelation. The adsorption capacity of Cr(VI) by CTS@nZVI-WSPC remains high after five cycles. The adsorbent is simple to operate, economical, efficient, and reusable, making it a promising candidate for the treatment of Cr(VI) in water.
{"title":"Enhanced Adsorptivity of Hexavalent Chromium in Aqueous Solutions Using CTS@nZVI Modified Wheat Straw-Derived Porous Carbon","authors":"Tiantian Deng, Hansheng Li, Su Ding, Feng Chen, Jingbao Fu, Junwei Zhao","doi":"10.3390/nano14110973","DOIUrl":"https://doi.org/10.3390/nano14110973","url":null,"abstract":"Using KOH-modified wheat straw as the precursor, wheat straw biochar was produced through carbonization at 500 °C. Subsequently, a synthetic material containing nano-zero-valent iron (nZVI) was prepared via liquid phase reduction (nZVI-WSPC). To enhance its properties, chitosan (CTS) was used by crosslinking to form the new adsorbent named CTS@nZVI-WSPC. The impact of CTS on parameters such as mass ratio, initial pH value, and adsorbent dosage on the adsorption efficiency of Cr(VI) in solution was investigated through one-factor experiments. Isotherm adsorption and thermodynamic analysis demonstrated that the adsorption of Cr(VI) by CTS@nZVI-WSPC conforms to the Langmuir model, with a maximum adsorption capacity of 147.93 mg/g, and the adsorption process is endothermic. Kinetic analysis revealed that the adsorption process follows a pseudo-second-order kinetic model. The adsorption mechanism, as elucidated by SEM, FTIR, XPS, and XRD, suggests that the process may involve multiple mechanisms, including pore adsorption, electrostatic adsorption, chemical reduction, and surface chelation. The adsorption capacity of Cr(VI) by CTS@nZVI-WSPC remains high after five cycles. The adsorbent is simple to operate, economical, efficient, and reusable, making it a promising candidate for the treatment of Cr(VI) in water.","PeriodicalId":508599,"journal":{"name":"Nanomaterials","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141268716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cristóbal Pinto García, Arianne Maine, Rodrigo A. Valenzuela-Fernández, Álvaro Aliaga Cerón, Patricia Barahona Huenchumil, Octavio Peña, I. Álvarez-Serrano, Andrés Ibáñez, Francisco Melo, Antonio Galdámez Silva
A new series of [Fe3−xLnx]O4 nanoparticles, with Ln = Gd; Dy; Lu and x = 0.05; 0.1; 0.15, was synthesized using the coprecipitation method. Analyses by X-ray diffraction (XRD), Rietveld refinement, and high-resolution transmission electron microscopy (HRTEM) indicate that all phases crystallized in space group Fd3¯m, characteristic of spinels. The XRD patterns, HRTEM, scanning electron microscopy analysis (SEM-EDS), and Raman spectra showed single phases. Transmission electron microscopy (TEM), Rietveld analysis, and Scherrer’s calculations confirm that these materials are nanoparticles with sizes in the range of ~6 nm to ~13 nm. Magnetic measurements reveal that the saturation magnetization (Ms) of the as-prepared ferrites increases with lanthanide chemical substitution (x), while the coercivity (Hc) has low values. The Raman analysis confirms that the compounds are ferrites and the Ms behavior can be explained by the relationship between the areas of the signals. The magnetic measurements indicate superparamagnetic behavior. The blocking temperatures (TB) were estimated from ZFC-FC measurements, and the use of the Néel equation enabled the magnetic anisotropy to be estimated.
{"title":"Structural Characterization and Magnetic Behavior Due to the Cationic Substitution of Lanthanides on Ferrite Nanoparticles","authors":"Cristóbal Pinto García, Arianne Maine, Rodrigo A. Valenzuela-Fernández, Álvaro Aliaga Cerón, Patricia Barahona Huenchumil, Octavio Peña, I. Álvarez-Serrano, Andrés Ibáñez, Francisco Melo, Antonio Galdámez Silva","doi":"10.3390/nano14110971","DOIUrl":"https://doi.org/10.3390/nano14110971","url":null,"abstract":"A new series of [Fe3−xLnx]O4 nanoparticles, with Ln = Gd; Dy; Lu and x = 0.05; 0.1; 0.15, was synthesized using the coprecipitation method. Analyses by X-ray diffraction (XRD), Rietveld refinement, and high-resolution transmission electron microscopy (HRTEM) indicate that all phases crystallized in space group Fd3¯m, characteristic of spinels. The XRD patterns, HRTEM, scanning electron microscopy analysis (SEM-EDS), and Raman spectra showed single phases. Transmission electron microscopy (TEM), Rietveld analysis, and Scherrer’s calculations confirm that these materials are nanoparticles with sizes in the range of ~6 nm to ~13 nm. Magnetic measurements reveal that the saturation magnetization (Ms) of the as-prepared ferrites increases with lanthanide chemical substitution (x), while the coercivity (Hc) has low values. The Raman analysis confirms that the compounds are ferrites and the Ms behavior can be explained by the relationship between the areas of the signals. The magnetic measurements indicate superparamagnetic behavior. The blocking temperatures (TB) were estimated from ZFC-FC measurements, and the use of the Néel equation enabled the magnetic anisotropy to be estimated.","PeriodicalId":508599,"journal":{"name":"Nanomaterials","volume":"116 18","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141272241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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