Pub Date : 2024-03-15DOI: 10.1088/2632-959x/ad34a5
Berg Dodson, Ryan Goul, Angelo Marshall, Aafiya, Kevin Bray, Dan Ewing, Michael Walsh, Judy Z Wu
Ultrathin (sub-2 nm) Al2O3/MgO memristors were recently developed using an in vacuo atomic layer deposition (ALD) process that minimizes unintended defects and prevents undesirable leakage current. These memristors provide a unique platform that allows oxygen vacancies (VO) to be inserted into the memristor with atomic precision and study how this affects the formation and rupture of conductive filaments (CFs) during memristive switching. Herein, we present a systematic study on three sets of ultrathin Al2O3/MgO atomic layer stack (ALS) memristors with VO-doping via modular MgO atomic layer insertion into an otherwise pristine insulating Al2O3 ALS using an in vacuo ALD. At a fixed memristor thickness of 17 Al2O3/MgO atomic layers (~1.9 nm), the properties of the memristors were found to be affected by the number and stacking pattern of the MgO atomic layers in the Al2O3/MgO ALS. Importantly, the trend of reduced low-state resistance and the increasing appearance of multi-step switches with an increasing number of MgO atomic layers suggests a direct correlation between the dimension and dynamic evolution of the conducting filaments and the VO concentration and distribution. Understanding such a correlation is critical to an atomic–scale control of the switching behavior of ultrathin memristors.
最近开发的超薄（小于 2 纳米）Al2O3/MgO 记忆晶体采用了真空原子层沉积（ALD）工艺，最大限度地减少了意外缺陷，防止了不良泄漏电流。这些忆阻器提供了一个独特的平台，允许以原子精度将氧空位（VO）插入忆阻器中，并研究这在忆阻开关过程中如何影响导电丝（CF）的形成和断裂。在这里，我们利用真空 ALD 方法，通过模块化氧化镁原子层插入到原本原始绝缘的 Al2O3 ALS 中，系统研究了三组掺杂了氧化氧的超薄 Al2O3/MgO 原子层堆栈（ALS）忆阻器。在 17 层 Al2O3/MgO 原子层（约 1.9 nm）的固定忆阻器厚度下，忆阻器的特性受到 Al2O3/MgO ALS 中氧化镁原子层的数量和堆叠模式的影响。重要的是，随着氧化镁原子层数的增加，低态电阻减小和多级开关出现的趋势表明，导电丝的尺寸和动态演化与 VO 的浓度和分布之间存在直接关联。了解这种相关性对于在原子尺度上控制超薄忆阻器的开关行为至关重要。
{"title":"Atomic-scale oxygen-vacancy engineering in Sub-2 nm thin Al2O3/MgO memristors","authors":"Berg Dodson, Ryan Goul, Angelo Marshall, Aafiya, Kevin Bray, Dan Ewing, Michael Walsh, Judy Z Wu","doi":"10.1088/2632-959x/ad34a5","DOIUrl":"https://doi.org/10.1088/2632-959x/ad34a5","url":null,"abstract":"\u0000 Ultrathin (sub-2 nm) Al2O3/MgO memristors were recently developed using an in vacuo atomic layer deposition (ALD) process that minimizes unintended defects and prevents undesirable leakage current. These memristors provide a unique platform that allows oxygen vacancies (VO) to be inserted into the memristor with atomic precision and study how this affects the formation and rupture of conductive filaments (CFs) during memristive switching. Herein, we present a systematic study on three sets of ultrathin Al2O3/MgO atomic layer stack (ALS) memristors with VO-doping via modular MgO atomic layer insertion into an otherwise pristine insulating Al2O3 ALS using an in vacuo ALD. At a fixed memristor thickness of 17 Al2O3/MgO atomic layers (~1.9 nm), the properties of the memristors were found to be affected by the number and stacking pattern of the MgO atomic layers in the Al2O3/MgO ALS. Importantly, the trend of reduced low-state resistance and the increasing appearance of multi-step switches with an increasing number of MgO atomic layers suggests a direct correlation between the dimension and dynamic evolution of the conducting filaments and the VO concentration and distribution. Understanding such a correlation is critical to an atomic–scale control of the switching behavior of ultrathin memristors.","PeriodicalId":501827,"journal":{"name":"Nano Express","volume":"13 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140238860","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}
Pub Date : 2024-03-15DOI: 10.1088/2632-959x/ad34a6
M. Jakhar, Yi Ding, B. Fahlman, V. Barone
The design of efficient single-atom catalysts (SACs) with optimal activity and selectivity for sustainable energy and environmental applications remains a challenge. In this work, comprehensive first-principles calculations are performed to validate the feasibility of single TM atoms (3d, 4d, and 5d series) embedded in two different conformations of graphitic carbon nitride (g-C3N4) monolayers. Additionally, we investigate the effect of nitrogen vacancies in the g-C3N4 monolayers on the absorption of SACs considering three potential absorption scenarios that correspond to different experimental conditions. Our results point to the most stable configurations with the lowest formation energies and indicate that the absorption of single TM atoms on-vacancy and on-center sites are more favorable than via-substitution. In addition to the thermodynamic stability, electrochemical stability is also investigated through the calculation of the dissolution potential of the SACs. Within the scenarios considered in this study, we find that Pt, Pd, Rh, Au, Ru, Ir, Cu, Co, Fe, and Ni will produce the most robust SACs on both (edge and bridge) N vacancy site of reduced g-C3N4. Our findings provide guidance for the design and development of g-C3N4 sheets decorated with single TM atoms for technological applications such as pollutant degradation, CO2 reduction, N2 fixation, selective oxidation, water splitting, and metal ion-based batteries.
{"title":"Computational design of single-atom catalysts embedded on reduced graphitic carbon nitride monolayers","authors":"M. Jakhar, Yi Ding, B. Fahlman, V. Barone","doi":"10.1088/2632-959x/ad34a6","DOIUrl":"https://doi.org/10.1088/2632-959x/ad34a6","url":null,"abstract":"\u0000 The design of efficient single-atom catalysts (SACs) with optimal activity and selectivity for sustainable energy and environmental applications remains a challenge. In this work, comprehensive first-principles calculations are performed to validate the feasibility of single TM atoms (3d, 4d, and 5d series) embedded in two different conformations of graphitic carbon nitride (g-C3N4) monolayers. Additionally, we investigate the effect of nitrogen vacancies in the g-C3N4 monolayers on the absorption of SACs considering three potential absorption scenarios that correspond to different experimental conditions. Our results point to the most stable configurations with the lowest formation energies and indicate that the absorption of single TM atoms on-vacancy and on-center sites are more favorable than via-substitution. In addition to the thermodynamic stability, electrochemical stability is also investigated through the calculation of the dissolution potential of the SACs. Within the scenarios considered in this study, we find that Pt, Pd, Rh, Au, Ru, Ir, Cu, Co, Fe, and Ni will produce the most robust SACs on both (edge and bridge) N vacancy site of reduced g-C3N4. Our findings provide guidance for the design and development of g-C3N4 sheets decorated with single TM atoms for technological applications such as pollutant degradation, CO2 reduction, N2 fixation, selective oxidation, water splitting, and metal ion-based batteries.","PeriodicalId":501827,"journal":{"name":"Nano Express","volume":"126 21","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140237818","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}
Pub Date : 2024-03-13DOI: 10.1088/2632-959x/ad2999
Valentina Baccetti, Ruomin Zhu, Zdenka Kuncic, Francesco Caravelli
Networks composed of nanoscale memristive components, such as nanowire and nanoparticle networks, have recently received considerable attention because of their potential use as neuromorphic devices. In this study, we explore ergodicity in memristive networks, showing that the performance on machine leaning tasks improves when these networks are tuned to operate at the edge between two global stability points. We find this lack of ergodicity is associated with the emergence of memory in the system. We measure the level of ergodicity using the Thirumalai-Mountain metric, and we show that in the absence of ergodicity, two different memristive network systems show improved performance when utilized as reservoir computers (RC). We highlight that it is also important to let the system synchronize to the input signal in order for the performance of the RC to exhibit improvements over the baseline.
{"title":"Ergodicity, lack thereof, and the performance of reservoir computing with memristive networks","authors":"Valentina Baccetti, Ruomin Zhu, Zdenka Kuncic, Francesco Caravelli","doi":"10.1088/2632-959x/ad2999","DOIUrl":"https://doi.org/10.1088/2632-959x/ad2999","url":null,"abstract":"Networks composed of nanoscale memristive components, such as nanowire and nanoparticle networks, have recently received considerable attention because of their potential use as neuromorphic devices. In this study, we explore ergodicity in memristive networks, showing that the performance on machine leaning tasks improves when these networks are tuned to operate at the edge between two global stability points. We find this lack of ergodicity is associated with the emergence of memory in the system. We measure the level of ergodicity using the Thirumalai-Mountain metric, and we show that in the absence of ergodicity, two different memristive network systems show improved performance when utilized as reservoir computers (RC). We highlight that it is also important to let the system synchronize to the input signal in order for the performance of the RC to exhibit improvements over the baseline.","PeriodicalId":501827,"journal":{"name":"Nano Express","volume":"129 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140315679","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}
Due to the exponential increase in global energy consumption and the degradation of environmental conditions caused by fossil fuels, it is critical to improve inexhaustible and sustainable resources. Generally, solar energy is one of the clean and environmentally agreeable energy sources. By harvesting solar energy for photocatalysis and considering it as a promising solution for various energy generation applications such as hydrogen production. Herein we are using Cadmium Sulphide and Nickel-doped Cadmium Sulphide in 0.5, 1 and 5 weight percent which act as photocatalyst for water splitting which will eventually produce an enormous amount of Hydrogen (H2). Cadmium sulphide was prepared through the chemical precipitation method and Ni-CdS by hydrothermal technique. The purity and phase formation were examined by the X-ray diffraction (XRD) and validated via Rietveld refinement by using Full Prof software. The surface morphology and the structure of as-synthesized material were evaluated by Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscope (TEM) spectroscopic techniques. Following the results, the Ni-CdS nanocomposite having 1.0 wt% of Ni exhibits the highest H2 evolution rate of 9 mmolg−1 in 5 h with strong photo-stability, which is about 50 times higher than that of CdS. The material was tested to degrade organic dye for its photocatalytic operations. The newly prepared composite materials (CdS-Ni-NiO) were used for the photocatalytic degradation of the methylene blue (MB) dye. Ni(1.0 wt%)-CdS shows an optimal degradation percentage of 95.436 in the presence of artificial solar light in 90 min. Crystal growth mechanism shows the spherical structure of CdS agglomerate to form nanorods structure when doped with Ni metal which is also verified by the TEM images of CdS and Ni-doped CdS. The XPS peaks observed at 854.88 eV and 861.07 eV for Ni2+ with an energy separation of 6.18 eV confirmed the existence of NiO with Ni/CdS. The Raman bands of pure CdS and Ni (1.0 wt%)-CdS nanorods were observed at 300 cm-1 and 293 cm−1 for 1LO phonon and 601 cm−1 and 586 cm−1 for 2LO phonon corresponds. The Ni tuned the CdS band gap from 2.36 to 2.20 eV. The results pave the way for designing multi-component CdS-Ni nano-composites for highly efficient H2 evolution and other environmental applications.
{"title":"Growth of Ni loaded CdS in nanorods structure for photocatalytic and dye degradation applications under solar irradiation","authors":"Vikash Kumar, Benjamin Raj, Parmeshwar Kommu, Sanjeet Kumar Paswan, Gajendra Prasad Singh","doi":"10.1088/2632-959x/ad2c9c","DOIUrl":"https://doi.org/10.1088/2632-959x/ad2c9c","url":null,"abstract":"Due to the exponential increase in global energy consumption and the degradation of environmental conditions caused by fossil fuels, it is critical to improve inexhaustible and sustainable resources. Generally, solar energy is one of the clean and environmentally agreeable energy sources. By harvesting solar energy for photocatalysis and considering it as a promising solution for various energy generation applications such as hydrogen production. Herein we are using Cadmium Sulphide and Nickel-doped Cadmium Sulphide in 0.5, 1 and 5 weight percent which act as photocatalyst for water splitting which will eventually produce an enormous amount of Hydrogen (H<sub>2</sub>). Cadmium sulphide was prepared through the chemical precipitation method and Ni-CdS by hydrothermal technique. The purity and phase formation were examined by the X-ray diffraction (XRD) and validated via Rietveld refinement by using Full Prof software. The surface morphology and the structure of as-synthesized material were evaluated by Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscope (TEM) spectroscopic techniques. Following the results, the Ni-CdS nanocomposite having 1.0 wt% of Ni exhibits the highest H<sub>2</sub> evolution rate of 9 mmolg<sup>−1</sup> in 5 h with strong photo-stability, which is about 50 times higher than that of CdS. The material was tested to degrade organic dye for its photocatalytic operations. The newly prepared composite materials (CdS-Ni-NiO) were used for the photocatalytic degradation of the methylene blue (MB) dye. Ni(1.0 wt%)-CdS shows an optimal degradation percentage of 95.436 in the presence of artificial solar light in 90 min. Crystal growth mechanism shows the spherical structure of CdS agglomerate to form nanorods structure when doped with Ni metal which is also verified by the TEM images of CdS and Ni-doped CdS. The XPS peaks observed at 854.88 eV and 861.07 eV for Ni<sup>2+</sup> with an energy separation of 6.18 eV confirmed the existence of NiO with Ni/CdS. The Raman bands of pure CdS and Ni (1.0 wt%)-CdS nanorods were observed at 300 cm<sup>-1</sup> and 293 cm<sup>−1</sup> for 1LO phonon and 601 cm<sup>−1</sup> and 586 cm<sup>−1</sup> for 2LO phonon corresponds. The Ni tuned the CdS band gap from 2.36 to 2.20 eV. The results pave the way for designing multi-component CdS-Ni nano-composites for highly efficient H<sub>2</sub> evolution and other environmental applications.","PeriodicalId":501827,"journal":{"name":"Nano Express","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140315675","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}
Pub Date : 2024-03-11DOI: 10.1088/2632-959x/ad2c9d
Rohini Puliyasseri, Kiyekali H Yeptho, Dillibabu Sastikumar
Heteroatom-doped graphene oxide has a wide range of applications in bio-imaging and sensing. In this work, Graphene Oxide (GO) and Nitrogen-doped GO (NG) were synthesized by laser ablation of Graphene in ethanol. The dopant Diethylenetriamine (DETA) is used in different amounts for different nitrogen concentrations. Optical, morphological, structural, and elemental composition studies were done by UV–vis spectroscopy, FT-IR, FE-SEM, XRD, Raman, and EDAX analysis, respectively. The nitrogen doping on the surface of GO was confirmed by FT-IR and EDAX studies. Upon laser ablation with fundamental wavelength, the graphene is converted to spherical GO nanoparticles, and nitrogen doping is done to produce porous nano coral structured NG nanoparticles. The sensitivity and selectivity of GO and NG for ammonia, ethanol, and acetone target gaseous were investigated and compared. NG sample shows excellent sensitivity and selectivity towards acetone gas. And the Nitrogen-doped graphene oxide can be considered an ideal material for gas-sensing applications.
杂原子掺杂的氧化石墨烯在生物成像和传感方面有着广泛的应用。在这项工作中，通过激光烧蚀乙醇中的石墨烯，合成了氧化石墨烯（GO）和氮掺杂 GO（NG）。掺杂剂二乙烯三胺（DETA）的用量不同，氮的浓度也不同。分别通过紫外-可见光谱、傅立叶变换红外光谱、FE-SEM、XRD、拉曼和 EDAX 分析进行了光学、形貌、结构和元素组成研究。FT-IR 和 EDAX 研究证实了 GO 表面的氮掺杂。在基本波长的激光烧蚀下，石墨烯转化为球形的 GO 纳米粒子，氮掺杂则产生了多孔纳米珊瑚结构的 NG 纳米粒子。研究并比较了 GO 和 NG 对氨气、乙醇和丙酮目标气体的灵敏度和选择性。NG 样品对丙酮气体具有极佳的灵敏度和选择性。掺氮氧化石墨烯可被视为气体传感应用的理想材料。
{"title":"Synthesis of graphene oxide and nitrogen-doped graphene oxide by nanosecond pulsed laser ablation of graphene in liquid for fiber optic gas sensing application","authors":"Rohini Puliyasseri, Kiyekali H Yeptho, Dillibabu Sastikumar","doi":"10.1088/2632-959x/ad2c9d","DOIUrl":"https://doi.org/10.1088/2632-959x/ad2c9d","url":null,"abstract":"Heteroatom-doped graphene oxide has a wide range of applications in bio-imaging and sensing. In this work, Graphene Oxide (GO) and Nitrogen-doped GO (NG) were synthesized by laser ablation of Graphene in ethanol. The dopant Diethylenetriamine (DETA) is used in different amounts for different nitrogen concentrations. Optical, morphological, structural, and elemental composition studies were done by UV–vis spectroscopy, FT-IR, FE-SEM, XRD, Raman, and EDAX analysis, respectively. The nitrogen doping on the surface of GO was confirmed by FT-IR and EDAX studies. Upon laser ablation with fundamental wavelength, the graphene is converted to spherical GO nanoparticles, and nitrogen doping is done to produce porous nano coral structured NG nanoparticles. The sensitivity and selectivity of GO and NG for ammonia, ethanol, and acetone target gaseous were investigated and compared. NG sample shows excellent sensitivity and selectivity towards acetone gas. And the Nitrogen-doped graphene oxide can be considered an ideal material for gas-sensing applications.","PeriodicalId":501827,"journal":{"name":"Nano Express","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140315594","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}
Pub Date : 2024-03-11DOI: 10.1088/2632-959x/ad2c9b
Makoto Sakurai
Emergent functionalities created by applying mechanical stress to flexible devices using SnO2 microrods and Ga2O3/SnO2-core/shell microribbons are reviewed. Dynamic lattice defect engineering through application of mechanical stress and a voltage to the SnO2 microrod device leads to a reversible semiconductor-insulator transition through lattice defect creation and healing, providing an effective and simple solution to the persistent photoconductivity (PPC) problem that has long plagued UV semiconductor photosensors. Here, lattice defects are created near slip planes in a rutile-structured microrod by applying mechanical stress and are healed by Joule heating by applying a voltage to the microrod. Nanoscale amorphous structuring makes the Ga2O3/SnO2-core/shell microribbon with a large SnO2 surface area more sensitive to changes in temperature, while mechanical bending of the wet device improves its sensitivity to adsorbed water molecules. These results illustrate the potential for developing flexible devices with new functionalities by enhancing the intrinsic properties of materials through miniaturization, mechanical stress, and hybridization.
{"title":"Emergent functionalities enhanced by mechanical stress in SnO2-based flexible devices","authors":"Makoto Sakurai","doi":"10.1088/2632-959x/ad2c9b","DOIUrl":"https://doi.org/10.1088/2632-959x/ad2c9b","url":null,"abstract":"Emergent functionalities created by applying mechanical stress to flexible devices using SnO<sub>2</sub> microrods and Ga<sub>2</sub>O<sub>3</sub>/SnO<sub>2</sub>-core/shell microribbons are reviewed. Dynamic lattice defect engineering through application of mechanical stress and a voltage to the SnO<sub>2</sub> microrod device leads to a reversible semiconductor-insulator transition through lattice defect creation and healing, providing an effective and simple solution to the persistent photoconductivity (PPC) problem that has long plagued UV semiconductor photosensors. Here, lattice defects are created near slip planes in a rutile-structured microrod by applying mechanical stress and are healed by Joule heating by applying a voltage to the microrod. Nanoscale amorphous structuring makes the Ga<sub>2</sub>O<sub>3</sub>/SnO<sub>2</sub>-core/shell microribbon with a large SnO<sub>2</sub> surface area more sensitive to changes in temperature, while mechanical bending of the wet device improves its sensitivity to adsorbed water molecules. These results illustrate the potential for developing flexible devices with new functionalities by enhancing the intrinsic properties of materials through miniaturization, mechanical stress, and hybridization.","PeriodicalId":501827,"journal":{"name":"Nano Express","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140316959","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}
Pub Date : 2024-03-06DOI: 10.1088/2632-959x/ad2b84
Peng Wang, Bo Gao, Wenjun Liu
Two-dimensional (2D) semiconducting materials with a single atomic layer display exceptional structural symmetry and band structures, making them the most promising candidates for investigating the spin-valley coupling effect and fabricating novel optoelectronic devices. Their atomic thinness also makes it easy to adjust their excitonic optical response through plasma treatment or thermal annealing. In this study, we present a simple technique for modifying the optical properties of monolayer MoS2 by briefly exposing it to laser irradiation in ambient conditions. Initially, this exposure resulted in a nearly twofold increase in photoluminescence (PL) intensity, with the neutral exciton intensity increasing while the trion exciton intensity decreased. We propose that oxygen-related functional groups, such as O2 and H2O from the surrounding air, adsorb onto MoS2 and extract extra electrons, which enhances exciton emission while reducing trion emission. In a subsequent stage, both exciton intensities decreased as all extra electrons were depleted. Additionally, any structural distortions or potential damage were found to decrease the PL intensity, and these changes were linked to alterations in the Raman spectra.
{"title":"In situ doping effect in monolayer MoS2 via laser irradiation","authors":"Peng Wang, Bo Gao, Wenjun Liu","doi":"10.1088/2632-959x/ad2b84","DOIUrl":"https://doi.org/10.1088/2632-959x/ad2b84","url":null,"abstract":"Two-dimensional (2D) semiconducting materials with a single atomic layer display exceptional structural symmetry and band structures, making them the most promising candidates for investigating the spin-valley coupling effect and fabricating novel optoelectronic devices. Their atomic thinness also makes it easy to adjust their excitonic optical response through plasma treatment or thermal annealing. In this study, we present a simple technique for modifying the optical properties of monolayer MoS<sub>2</sub> by briefly exposing it to laser irradiation in ambient conditions. Initially, this exposure resulted in a nearly twofold increase in photoluminescence (PL) intensity, with the neutral exciton intensity increasing while the trion exciton intensity decreased. We propose that oxygen-related functional groups, such as O<sub>2</sub> and H<sub>2</sub>O from the surrounding air, adsorb onto MoS<sub>2</sub> and extract extra electrons, which enhances exciton emission while reducing trion emission. In a subsequent stage, both exciton intensities decreased as all extra electrons were depleted. Additionally, any structural distortions or potential damage were found to decrease the PL intensity, and these changes were linked to alterations in the Raman spectra.","PeriodicalId":501827,"journal":{"name":"Nano Express","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140315486","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}
In this study, a green and highly efficient method was proposed to synthesize nano-silver chloride (nano-AgCl) using spent mushroom substrate (SMS) extract as a cheap reactant. Nanoparticles were characterized by a series of techniques like x-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), which showed the formation of near-spherical silver chloride nanoparticles with an average size of about 8.30 nm. Notably, the synthesized nano-silver chloride has a more prominent antibacterial effect against Ralstonia solanacearum (EC50 = 5.18 mg L−1) than non-nano-sized silver chloride particles, nano-silver chloride synthesized by chemical method, and commercial pesticides. In-depth, the study of the mechanism revealed that nano-silver chloride could cause cell membrane disruption, DNA damage and intracellular generation of reactive oxygen species (·OH, ·O2− and 1O2), leading to peroxidation damage in Ralstonia solanacearum (R. solanacearum). Moreover, the reaction between nano-silver chloride and bacteria could be driven by intermolecular forces instead of electrostatic interactions. Our study provides a new approach to synthesizing nano-silver chloride as a highly efficient antibacterial agent and broadens the utilization of agricultural waste spent mushroom substrate.
{"title":"Biosynthesis of high antibacterial silver chloride nanoparticles against Ralstonia solanacearum using spent mushroom substrate extract","authors":"Wenjing Mo, Chunmei Yao, Hongsen Chen, Aisha Khalfan Nassor, Fangze Gui, Ciqing Hong, Tianpei Huang, Xiong Guan, Lei Xu, Xiaohong Pan","doi":"10.1088/2632-959x/ad2b81","DOIUrl":"https://doi.org/10.1088/2632-959x/ad2b81","url":null,"abstract":"In this study, a green and highly efficient method was proposed to synthesize nano-silver chloride (nano-AgCl) using spent mushroom substrate (SMS) extract as a cheap reactant. Nanoparticles were characterized by a series of techniques like x-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), which showed the formation of near-spherical silver chloride nanoparticles with an average size of about 8.30 nm. Notably, the synthesized nano-silver chloride has a more prominent antibacterial effect against <italic toggle=\"yes\">Ralstonia solanacearum</italic> (EC<sub>50</sub> = 5.18 mg L<sup>−1</sup>) than non-nano-sized silver chloride particles, nano-silver chloride synthesized by chemical method, and commercial pesticides. In-depth, the study of the mechanism revealed that nano-silver chloride could cause cell membrane disruption, DNA damage and intracellular generation of reactive oxygen species (·OH, ·O<sup>2−</sup> and <sup>1</sup>O<sub>2</sub>), leading to peroxidation damage in <italic toggle=\"yes\">Ralstonia solanacearum</italic> (<italic toggle=\"yes\">R. solanacearum</italic>). Moreover, the reaction between nano-silver chloride and bacteria could be driven by intermolecular forces instead of electrostatic interactions. Our study provides a new approach to synthesizing nano-silver chloride as a highly efficient antibacterial agent and broadens the utilization of agricultural waste spent mushroom substrate.","PeriodicalId":501827,"journal":{"name":"Nano Express","volume":"72 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140315592","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}
Pub Date : 2024-03-06DOI: 10.1088/2632-959x/ad2b83
Ashish Garg, Swati Bishnoi
The transport of fluids in nanometer and Angstrom-sized pores has gotten much attention because of its potential uses in nanotechnology, energy storage, and healthcare sectors. Understanding the distinct material properties of fluids in such close confinement is critical for enhancing their performance in various applications. These properties dictate the fluid’s behavior and play a crucial role in determining flow dynamics, transport processes, and, ultimately, the performance of nanoscale devices. Remarkably, many researchers observed that the size of the geometry, such as the diameter of the confining nanotube, exerts a profound and intriguing influence on the material properties of nanoconfined fluids, including on the critical parameters such as density, viscosity, and slip length. Many researchers tried to model these material properties: viscosity η, density ρ, and slip λ using various models with many dependencies on the tube diameter. It is somewhat confusing and tough to decide which model is appropriate and needs to be incorporated in the numerical simulation. In this paper, we tried to propose a simple single equation for each nano confined material property such as for density ρ(D)/ρo=a+b/(D−c)n, viscosity η(D)/ηo=a+b/(D−c)n, and the slip length
{"title":"An empirical experimental observations and MD simulation data-based model for the material properties of confined fluids in nano/Angstrom size tubes","authors":"Ashish Garg, Swati Bishnoi","doi":"10.1088/2632-959x/ad2b83","DOIUrl":"https://doi.org/10.1088/2632-959x/ad2b83","url":null,"abstract":"The transport of fluids in nanometer and Angstrom-sized pores has gotten much attention because of its potential uses in nanotechnology, energy storage, and healthcare sectors. Understanding the distinct material properties of fluids in such close confinement is critical for enhancing their performance in various applications. These properties dictate the fluid’s behavior and play a crucial role in determining flow dynamics, transport processes, and, ultimately, the performance of nanoscale devices. Remarkably, many researchers observed that the size of the geometry, such as the diameter of the confining nanotube, exerts a profound and intriguing influence on the material properties of nanoconfined fluids, including on the critical parameters such as density, viscosity, and slip length. Many researchers tried to model these material properties: viscosity <italic toggle=\"yes\">η</italic>, density <italic toggle=\"yes\">ρ</italic>, and slip <italic toggle=\"yes\">λ</italic> using various models with many dependencies on the tube diameter. It is somewhat confusing and tough to decide which model is appropriate and needs to be incorporated in the numerical simulation. In this paper, we tried to propose a simple single equation for each nano confined material property such as for density <inline-formula>\u0000<tex-math>\u0000<?CDATA $rho {(D)/{rho }_{o}=a+b/(D-c)}^{n}$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mi>ρ</mml:mi><mml:msup><mml:mrow><mml:mo stretchy=\"false\">(</mml:mo><mml:mi>D</mml:mi><mml:mo stretchy=\"false\">)</mml:mo><mml:mrow><mml:mo stretchy=\"true\">/</mml:mo></mml:mrow><mml:msub><mml:mrow><mml:mi>ρ</mml:mi></mml:mrow><mml:mrow><mml:mi>o</mml:mi></mml:mrow></mml:msub><mml:mo>=</mml:mo><mml:mi>a</mml:mi><mml:mo>+</mml:mo><mml:mi>b</mml:mi><mml:mrow><mml:mo stretchy=\"true\">/</mml:mo></mml:mrow><mml:mo stretchy=\"false\">(</mml:mo><mml:mi>D</mml:mi><mml:mo>−</mml:mo><mml:mi>c</mml:mi><mml:mo stretchy=\"false\">)</mml:mo></mml:mrow><mml:mrow><mml:mi>n</mml:mi></mml:mrow></mml:msup></mml:math>\u0000<inline-graphic xlink:href=\"nanoxad2b83ieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>, viscosity <inline-formula>\u0000<tex-math>\u0000<?CDATA $eta {(D)/{eta }_{o}=a+b/(D-c)}^{n}$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mi>η</mml:mi><mml:msup><mml:mrow><mml:mo stretchy=\"false\">(</mml:mo><mml:mi>D</mml:mi><mml:mo stretchy=\"false\">)</mml:mo><mml:mrow><mml:mo stretchy=\"true\">/</mml:mo></mml:mrow><mml:msub><mml:mrow><mml:mi>η</mml:mi></mml:mrow><mml:mrow><mml:mi>o</mml:mi></mml:mrow></mml:msub><mml:mo>=</mml:mo><mml:mi>a</mml:mi><mml:mo>+</mml:mo><mml:mi>b</mml:mi><mml:mrow><mml:mo stretchy=\"true\">/</mml:mo></mml:mrow><mml:mo stretchy=\"false\">(</mml:mo><mml:mi>D</mml:mi><mml:mo>−</mml:mo><mml:mi>c</mml:mi><mml:mo stretchy=\"false\">)</mml:mo></mml:mrow><mml:mrow><mml:mi>n</mml:mi></mml:mrow></mml:msup></mml:math>\u0000<inline-graphic xlink:href=\"nanoxad2b83ieqn2.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>, and the slip length <italic toggle=\"yes","PeriodicalId":501827,"journal":{"name":"Nano Express","volume":"33 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140315593","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}
Pub Date : 2024-03-05DOI: 10.1088/2632-959x/ad2b7f
W Aadinath, Vignesh Muthuvijayan
Fenton reaction-mediated reactive oxygen species (ROS) generation by the iron oxide nanoparticles (IONPs) is responsible for its antibacterial activity. In general, IONPs are surface-coated to facilitate stability, control over size, biocompatibility, solubility, etc. We hypothesize that the extent of surface coating onto the IONPs might affect Fenton reaction-mediated ROS generation, which would eventually impact its antibacterial activity. In the present study, IONPs were prepared using the co-precipitation method, and different weights of oleic acid (OA) were loaded onto the IONPs. Pristine IONPs and oleic acid-coated iron oxide nanoparticles (OA-IONPs) were characterized using Fourier transform-infrared spectroscopy, dynamic light scattering, transmission electron microscopy, X-ray diffraction, vibrating sample magnetometry, goniometer, and thermogravimetric analysis. We found that magnetic susceptibilities of the IONPs were significantly enhanced with an increase in OA loading on the IONPs. The antibacterial study showed that the percentage inhibition was inversely related to the extent of oleic acid coating on the IONPs. The dependency of ROS generation on the extent of surface coating over IONPs was demonstrated using the 2’,7’-dichlorodihydrofluorescein diacetate (DCFDA) assay. Although pristine IONPs showed the least ROS generation, they exhibited maximum percentage inhibition of bacteria. This might be due to mechanical damage to the bacterial cells because of their crystalline nature. In vitro biocompatibility study conducted on L929 fibroblast cell lines indicated that all the nanoparticle preparations were cytocompatible. This study concluded that the extent of surface coating influences the Fenton reaction-mediated ROS generation and also the magnetic susceptibilities of the IONPs.
{"title":"Influence of oleic acid coating on the magnetic susceptibility and Fenton reaction-mediated ROS generation by the iron oxide nanoparticles","authors":"W Aadinath, Vignesh Muthuvijayan","doi":"10.1088/2632-959x/ad2b7f","DOIUrl":"https://doi.org/10.1088/2632-959x/ad2b7f","url":null,"abstract":"Fenton reaction-mediated reactive oxygen species (ROS) generation by the iron oxide nanoparticles (IONPs) is responsible for its antibacterial activity. In general, IONPs are surface-coated to facilitate stability, control over size, biocompatibility, solubility, etc. We hypothesize that the extent of surface coating onto the IONPs might affect Fenton reaction-mediated ROS generation, which would eventually impact its antibacterial activity. In the present study, IONPs were prepared using the co-precipitation method, and different weights of oleic acid (OA) were loaded onto the IONPs. Pristine IONPs and oleic acid-coated iron oxide nanoparticles (OA-IONPs) were characterized using Fourier transform-infrared spectroscopy, dynamic light scattering, transmission electron microscopy, X-ray diffraction, vibrating sample magnetometry, goniometer, and thermogravimetric analysis. We found that magnetic susceptibilities of the IONPs were significantly enhanced with an increase in OA loading on the IONPs. The antibacterial study showed that the percentage inhibition was inversely related to the extent of oleic acid coating on the IONPs. The dependency of ROS generation on the extent of surface coating over IONPs was demonstrated using the 2’,7’-dichlorodihydrofluorescein diacetate (DCFDA) assay. Although pristine IONPs showed the least ROS generation, they exhibited maximum percentage inhibition of bacteria. This might be due to mechanical damage to the bacterial cells because of their crystalline nature. <italic toggle=\"yes\">In vitro</italic> biocompatibility study conducted on L929 fibroblast cell lines indicated that all the nanoparticle preparations were cytocompatible. This study concluded that the extent of surface coating influences the Fenton reaction-mediated ROS generation and also the magnetic susceptibilities of the IONPs.","PeriodicalId":501827,"journal":{"name":"Nano Express","volume":"66 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140315596","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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