As the world grapples with the escalating threat of global warming, exploring sustainable agricultural practices has become imperative. Carbon sequestration is one such efficient method to mitigate carbon emissions and reduce global warming. Among the numerous sequestration options, terrestrial methods, notably via horticultural crops, have enormous potential. Horticultural crops, which encompass a diverse array of fruits, vegetables, plantations, and ornamental plants, offer a unique chance to sequester a considerable amount of atmospheric carbon dioxide. In particular, perennial horticultural systems provide numerous benefits over annual crops, such as increased productivity, reduced water and input requirements, and higher economic returns via carbon credits. However, the transition from annual to perennial crops presents logistical and financial challenges. The carbon sequestration capacity of plantations and horticulture crops is larger, at 16.4 Gt C, compared to the agroforestry system, which is at 6.3 Gt C. In order to fully use this capacity, it is essential to employ effective carbon management systems. These methods include growing higher biomass, recycling agricultural waste, employing animal manure, switching to perennial crops, adopting crop rotation, and encouraging agroforestry systems. Although there are advantages, substantial initial investments and continuous management are required to ensure effectiveness, and these demands might hinder widespread acceptance. This review emphasizes the critical role of horticulture systems in improving soil carbon levels, soil organic matter dynamics, different forms of carbon, and their overall potential for carbon sequestration. By unlocking the potential of horticultural crops to sequester carbon, we can help minimize atmospheric carbon dioxide levels, lessen the impact of climate change, and ensure nutritional security and economic benefits.
{"title":"Unlocking the Carbon Sequestration Potential of Horticultural Crops","authors":"T. Ilakiya, Ettiyagounder Parameswari, Ramakrishna Swarnapriya, Gunasekaran Yazhini, Periasamy Kalaiselvi, Veeraswamy Davamani, Sudha Singh, Nedunchezhiyan Vinothini, Chelladurai Dharani, Sneha Leela Garnepudi, Ramasamy Ajaykumar","doi":"10.3390/c10030065","DOIUrl":"https://doi.org/10.3390/c10030065","url":null,"abstract":"As the world grapples with the escalating threat of global warming, exploring sustainable agricultural practices has become imperative. Carbon sequestration is one such efficient method to mitigate carbon emissions and reduce global warming. Among the numerous sequestration options, terrestrial methods, notably via horticultural crops, have enormous potential. Horticultural crops, which encompass a diverse array of fruits, vegetables, plantations, and ornamental plants, offer a unique chance to sequester a considerable amount of atmospheric carbon dioxide. In particular, perennial horticultural systems provide numerous benefits over annual crops, such as increased productivity, reduced water and input requirements, and higher economic returns via carbon credits. However, the transition from annual to perennial crops presents logistical and financial challenges. The carbon sequestration capacity of plantations and horticulture crops is larger, at 16.4 Gt C, compared to the agroforestry system, which is at 6.3 Gt C. In order to fully use this capacity, it is essential to employ effective carbon management systems. These methods include growing higher biomass, recycling agricultural waste, employing animal manure, switching to perennial crops, adopting crop rotation, and encouraging agroforestry systems. Although there are advantages, substantial initial investments and continuous management are required to ensure effectiveness, and these demands might hinder widespread acceptance. This review emphasizes the critical role of horticulture systems in improving soil carbon levels, soil organic matter dynamics, different forms of carbon, and their overall potential for carbon sequestration. By unlocking the potential of horticultural crops to sequester carbon, we can help minimize atmospheric carbon dioxide levels, lessen the impact of climate change, and ensure nutritional security and economic benefits.","PeriodicalId":503899,"journal":{"name":"C","volume":"34 46","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141800480","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}
Marwa Gatrouni, N. Asses, J. Bedia, C. Belver, C. B. Molina, Nadia Mzoughi
Biochar and carbon adsorbents from citrus waste have been prepared by thermal and chemical treatments; they have been used in the aqueous phase adsorption of acetaminophen (ACE) as a model emerging pollutant. These materials were fully characterized by elemental analysis, X-ray fluorescence (TXRF), adsorption/desorption of nitrogen, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), point of zero charge (pHpzc), scanning electron microscopy (SEM), and thermogravimetric analyses (TGA/DTG/DTA). A magnetic carbon adsorbent was obtained by FeCl3 activation under an inert atmosphere, giving rise to the best results in ACE adsorption. Adsorption equilibrium data were obtained at 298, 318, and 338 K and fitted to different models, corresponding to the best fitting to the Redlich–Peterson model. The maximum adsorption capacity at equilibrium resulted in 45 mg ACE·g−1 carbon at 338 K. The free energy values were calculated, and values between −21.03 and −23.00 kJ·mol‒1 were obtained; the negative values confirmed the spontaneity of the process. The enthalpy and entropy of the adsorption process were obtained, giving rise to −6.4 kJ·mol‒1 and 49 J·mol‒1·K‒1, respectively, indicating a slightly exothermic process and an increase in the randomness at the solid–liquid interface upon adsorption, respectively. The adsorption kinetics were also studied, with the Elovich model being the one that gave rise to the best-fitting results.
{"title":"Acetaminophen Adsorption on Carbon Materials from Citrus Waste","authors":"Marwa Gatrouni, N. Asses, J. Bedia, C. Belver, C. B. Molina, Nadia Mzoughi","doi":"10.3390/c10020053","DOIUrl":"https://doi.org/10.3390/c10020053","url":null,"abstract":"Biochar and carbon adsorbents from citrus waste have been prepared by thermal and chemical treatments; they have been used in the aqueous phase adsorption of acetaminophen (ACE) as a model emerging pollutant. These materials were fully characterized by elemental analysis, X-ray fluorescence (TXRF), adsorption/desorption of nitrogen, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), point of zero charge (pHpzc), scanning electron microscopy (SEM), and thermogravimetric analyses (TGA/DTG/DTA). A magnetic carbon adsorbent was obtained by FeCl3 activation under an inert atmosphere, giving rise to the best results in ACE adsorption. Adsorption equilibrium data were obtained at 298, 318, and 338 K and fitted to different models, corresponding to the best fitting to the Redlich–Peterson model. The maximum adsorption capacity at equilibrium resulted in 45 mg ACE·g−1 carbon at 338 K. The free energy values were calculated, and values between −21.03 and −23.00 kJ·mol‒1 were obtained; the negative values confirmed the spontaneity of the process. The enthalpy and entropy of the adsorption process were obtained, giving rise to −6.4 kJ·mol‒1 and 49 J·mol‒1·K‒1, respectively, indicating a slightly exothermic process and an increase in the randomness at the solid–liquid interface upon adsorption, respectively. The adsorption kinetics were also studied, with the Elovich model being the one that gave rise to the best-fitting results.","PeriodicalId":503899,"journal":{"name":"C","volume":" 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141369869","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}
Modifying the polymer matrix by nanoparticles can be a promising approach to improve the performance of fiber-reinforced polymer (FRP) composites. Organic solvents are usually used for dispersing graphene oxide (GO) well in the polymer matrix. In this study, a green, facile, and efficient approach was developed to prepare epoxy/GO nanocomposites. In situ polymerization is used for synthesizing nanocomposites, eliminating the need for organic solvents and surfactants. By loading just 0.6 wt% of GO into the epoxy resin, Young’s modulus, tensile strength, and toughness improved by 38%, 46%, and 143%, respectively. Fractography analysis indicates smooth fracture surfaces of pure resin that changed to highly toughened fracture surfaces in this nanocomposite. Plastic deformation, crack pinning, and deflection contributed to improving the toughness of the nanocomposites. FTIR investigations show that amide bonding was created by the reaction of the carboxylic acid groups in GO with some amine groups in the curing agent during the dispersion processes.
{"title":"In Situ Processing to Achieve High-Performance Epoxy Nanocomposites with Low Graphene Oxide Loading","authors":"Miraidin Mirzapour, Mathieu Robert, B. Benmokrane","doi":"10.3390/c10020052","DOIUrl":"https://doi.org/10.3390/c10020052","url":null,"abstract":"Modifying the polymer matrix by nanoparticles can be a promising approach to improve the performance of fiber-reinforced polymer (FRP) composites. Organic solvents are usually used for dispersing graphene oxide (GO) well in the polymer matrix. In this study, a green, facile, and efficient approach was developed to prepare epoxy/GO nanocomposites. In situ polymerization is used for synthesizing nanocomposites, eliminating the need for organic solvents and surfactants. By loading just 0.6 wt% of GO into the epoxy resin, Young’s modulus, tensile strength, and toughness improved by 38%, 46%, and 143%, respectively. Fractography analysis indicates smooth fracture surfaces of pure resin that changed to highly toughened fracture surfaces in this nanocomposite. Plastic deformation, crack pinning, and deflection contributed to improving the toughness of the nanocomposites. FTIR investigations show that amide bonding was created by the reaction of the carboxylic acid groups in GO with some amine groups in the curing agent during the dispersion processes.","PeriodicalId":503899,"journal":{"name":"C","volume":" 16","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141373889","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}
R. G. Morais, N. Rey‐Raap, J. L. Figueiredo, Manuel F. R. Pereira
Glucose-derived carbon hybrids were synthesized by hydrothermal treatment in the presence of oxidized carbon nanotubes. Additionally, iron and nitrogen functionalities were incorporated into the carbon structure using different methodologies. The introduction of iron and nitrogen in a single step under a H2 atmosphere favored the formation of quaternary nitrogen and oxidized nitrogen, whereas the incorporation of nitrogen under an N2 atmosphere after doping the hybrids with iron mainly produced pyridinic nitrogen. The samples were characterized by scanning electron microscopy, X-ray spectroscopy, adsorption isotherms, inductively coupled plasma optical emission spectrometry, and Raman spectroscopy. The presence of iron and nitrogen in the carbons increases the onset potential toward oxygen reduction in KOH 0.1 mol L−1 by 130 mV (0.83 V), in comparison to carbonized glucose, whereas the reaction mechanism shifts closer to a direct pathway and the formation of HO2− decreases to 25% (3.5 electrons). The reaction rate also increased in comparison to the carbonized glucose, as observed by the decrease in the Tafel slope value from 117 to 61 mV dec−1. Furthermore, the incorporation of iron and nitrogen in a single step enhanced the short-term performance of the prepared electrocatalysts, which may also be due to the higher relative amount of quaternary nitrogen.
{"title":"Insights into the Electrocatalytic Activity of Fe,N-Glucose/Carbon Nanotube Hybrids for the Oxygen Reduction Reaction","authors":"R. G. Morais, N. Rey‐Raap, J. L. Figueiredo, Manuel F. R. Pereira","doi":"10.3390/c10020047","DOIUrl":"https://doi.org/10.3390/c10020047","url":null,"abstract":"Glucose-derived carbon hybrids were synthesized by hydrothermal treatment in the presence of oxidized carbon nanotubes. Additionally, iron and nitrogen functionalities were incorporated into the carbon structure using different methodologies. The introduction of iron and nitrogen in a single step under a H2 atmosphere favored the formation of quaternary nitrogen and oxidized nitrogen, whereas the incorporation of nitrogen under an N2 atmosphere after doping the hybrids with iron mainly produced pyridinic nitrogen. The samples were characterized by scanning electron microscopy, X-ray spectroscopy, adsorption isotherms, inductively coupled plasma optical emission spectrometry, and Raman spectroscopy. The presence of iron and nitrogen in the carbons increases the onset potential toward oxygen reduction in KOH 0.1 mol L−1 by 130 mV (0.83 V), in comparison to carbonized glucose, whereas the reaction mechanism shifts closer to a direct pathway and the formation of HO2− decreases to 25% (3.5 electrons). The reaction rate also increased in comparison to the carbonized glucose, as observed by the decrease in the Tafel slope value from 117 to 61 mV dec−1. Furthermore, the incorporation of iron and nitrogen in a single step enhanced the short-term performance of the prepared electrocatalysts, which may also be due to the higher relative amount of quaternary nitrogen.","PeriodicalId":503899,"journal":{"name":"C","volume":"81 18","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140964467","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}
Sereno Sacchet, F. Valentini, Alice Benin, Marco Guidolin, Riccardo Po, L. Fambri
In this work, passive cooling systems for the revamping of existent silicon photovoltaic (PV) cells were developed and analysed in order to mitigate the efficiency loss caused by temperature rise in the hot season. For this purpose, expanded graphite (EG) was used to stabilize a phase change material (PCM) with a melting temperature close to 53 °C in order to realize thermal management systems (TMSs) able to store heat at constant temperature during melting and releasing it in crystallization. In particular, stearic and palmitic acid mixture (PA-SA) was shape-stabilized in EG at different concentrations (10, 12 and 14 part per hundred ratio) under vacuum into a rotary evaporation apparatus followed by cold compaction; PA-SA leakage was reduced due to its intercalation between the graphite lamellae, and the thermal conductivity necessary to maximize the heat transfer to a bulk TMS was improved via powder cold compaction, which minimizes voids and creates preferential thermal conductive patterns. The composite materials, stable till 150 °C, were tested by differential scanning calorimetry (DSC) at 1 °C/min to precisely determine the phase transition temperatures and the enthalpic content, which was only slightly reduced from 196 J/g of the neat PCM to 169 J/g due to the very low EG fraction necessary for the stabilization. Despite only the 14:100 EG-to-PA-SA ratio, the system’s thermal conductivity was enhanced 40 times with respect to the neat PCM (from 0.2 to 8.3 W/(m K), value never reached in works present in the literature), with a good convergence of the values evaluated through hot disk tests and laser flash analysis (LFA), finding correlation with both graphitic content and density. In order to completely avoid leaking with the consequent dispersion of PCM in the environment during the final application, all the samples were encapsulated in a PE-made film. The mechanical properties were evaluated with compression tests at 30 °C and 80 °C simulating a possible compressive stress deriving from the contact needed to maintain the TMS position on the rear of the PV cells. Finally, the material response was simulated by imposing thermal cycles into a climatic chamber and reproducing the three hottest and coldest days of summer 2022 of two Italian locations, Verona (Veneto, 45° N, 11° E) and Gela (Sicily, 37° N, 14° E), thus highlighting the thermal management effects with delays in temperature increase and daily peak temperature smoothing. The role of EG is strategic for the processing and the properties of the resulting composites in order to realize a proper compromise between the melting enthalpy of PCM and the thermal conductivity enhancement given by EG.
{"title":"Expanded Graphite (EG) Stabilization of Stearic and Palmitic Acid Mixture for Thermal Management of Photovoltaic Cells","authors":"Sereno Sacchet, F. Valentini, Alice Benin, Marco Guidolin, Riccardo Po, L. Fambri","doi":"10.3390/c10020046","DOIUrl":"https://doi.org/10.3390/c10020046","url":null,"abstract":"In this work, passive cooling systems for the revamping of existent silicon photovoltaic (PV) cells were developed and analysed in order to mitigate the efficiency loss caused by temperature rise in the hot season. For this purpose, expanded graphite (EG) was used to stabilize a phase change material (PCM) with a melting temperature close to 53 °C in order to realize thermal management systems (TMSs) able to store heat at constant temperature during melting and releasing it in crystallization. In particular, stearic and palmitic acid mixture (PA-SA) was shape-stabilized in EG at different concentrations (10, 12 and 14 part per hundred ratio) under vacuum into a rotary evaporation apparatus followed by cold compaction; PA-SA leakage was reduced due to its intercalation between the graphite lamellae, and the thermal conductivity necessary to maximize the heat transfer to a bulk TMS was improved via powder cold compaction, which minimizes voids and creates preferential thermal conductive patterns. The composite materials, stable till 150 °C, were tested by differential scanning calorimetry (DSC) at 1 °C/min to precisely determine the phase transition temperatures and the enthalpic content, which was only slightly reduced from 196 J/g of the neat PCM to 169 J/g due to the very low EG fraction necessary for the stabilization. Despite only the 14:100 EG-to-PA-SA ratio, the system’s thermal conductivity was enhanced 40 times with respect to the neat PCM (from 0.2 to 8.3 W/(m K), value never reached in works present in the literature), with a good convergence of the values evaluated through hot disk tests and laser flash analysis (LFA), finding correlation with both graphitic content and density. In order to completely avoid leaking with the consequent dispersion of PCM in the environment during the final application, all the samples were encapsulated in a PE-made film. The mechanical properties were evaluated with compression tests at 30 °C and 80 °C simulating a possible compressive stress deriving from the contact needed to maintain the TMS position on the rear of the PV cells. Finally, the material response was simulated by imposing thermal cycles into a climatic chamber and reproducing the three hottest and coldest days of summer 2022 of two Italian locations, Verona (Veneto, 45° N, 11° E) and Gela (Sicily, 37° N, 14° E), thus highlighting the thermal management effects with delays in temperature increase and daily peak temperature smoothing. The role of EG is strategic for the processing and the properties of the resulting composites in order to realize a proper compromise between the melting enthalpy of PCM and the thermal conductivity enhancement given by EG.","PeriodicalId":503899,"journal":{"name":"C","volume":"123 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140977547","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}
L. Klimek, G. Gumienny, B. Januszewicz, R. Atraszkiewicz, K. Buczkowska
This paper presents a comparative analysis of ausferritic ductile cast iron matrix obtained through heat treatment and in its raw state. Ausferrite without heat treatment was achieved by modifying the chemical composition, while nodular graphite was produced using Inmold technology. The presence of compacted graphite in the as-cast ausferritic cast iron was attributed to elements that impede the crystallization of nodular graphite. This study demonstrates that an ausferritic matrix in ductile cast iron can be achieved by incorporating molybdenum in conjunction with nickel or copper. Thermal and derivative analysis (TDA) revealed a minor thermal effect during the transformation of austenite into bainitic ferrite in as-cast ausferritic cast iron. Furthermore, the transformation of austenite in cast iron containing nickel was observed to occur at a temperature of approximately 60 °C higher than in cast iron with copper. The structure of bainitic ferrite platelets in as-cast ausferritic ductile cast iron resembled that of Austempered Ductile Iron (ADI). It was revealed that the amount of austenite in as-cast ausferritic ductile cast iron is more than double that in ADI. The carbon content of austenite was estimated theoretically, revealing that alloying additives in the as-cast ausferritic ductile cast iron reduce the solubility of carbon in austenite, thereby significantly influencing the properties of the cast iron.
{"title":"Structural and Phase Analysis of the Ausferritic Ductile Cast Iron Matrix Obtained by Heat Treatment and in the Raw State","authors":"L. Klimek, G. Gumienny, B. Januszewicz, R. Atraszkiewicz, K. Buczkowska","doi":"10.3390/c10020045","DOIUrl":"https://doi.org/10.3390/c10020045","url":null,"abstract":"This paper presents a comparative analysis of ausferritic ductile cast iron matrix obtained through heat treatment and in its raw state. Ausferrite without heat treatment was achieved by modifying the chemical composition, while nodular graphite was produced using Inmold technology. The presence of compacted graphite in the as-cast ausferritic cast iron was attributed to elements that impede the crystallization of nodular graphite. This study demonstrates that an ausferritic matrix in ductile cast iron can be achieved by incorporating molybdenum in conjunction with nickel or copper. Thermal and derivative analysis (TDA) revealed a minor thermal effect during the transformation of austenite into bainitic ferrite in as-cast ausferritic cast iron. Furthermore, the transformation of austenite in cast iron containing nickel was observed to occur at a temperature of approximately 60 °C higher than in cast iron with copper. The structure of bainitic ferrite platelets in as-cast ausferritic ductile cast iron resembled that of Austempered Ductile Iron (ADI). It was revealed that the amount of austenite in as-cast ausferritic ductile cast iron is more than double that in ADI. The carbon content of austenite was estimated theoretically, revealing that alloying additives in the as-cast ausferritic ductile cast iron reduce the solubility of carbon in austenite, thereby significantly influencing the properties of the cast iron.","PeriodicalId":503899,"journal":{"name":"C","volume":"106 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140977998","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}
We explore the possibility of attaining valley-dependent tunnelling and confinement using proximity-induced spin-orbit couplings (SOCs) in graphene-based heterostructures. We consider gate-tunable asymmetric quantum dots (AQDs) on graphene heterostructures and exhibiting a C3v and/or C6v symmetry. By employing a tight-binding model, we explicitly reveal a pure valley confinement and valley signal in AQDs by streaming the valley local density, leading to valley-charge separation in real space. The confinement of the valley quasi-bound states is sensitive to the locally induced SOCs and to the spatial distribution of the induced AQDs; it is also robust against on-site disorder. The adopted process of attaining a pure valley-Hall conductivity and confinement with zero charge currents is expected to provide more options towards valley-dependent electron optics.
{"title":"Gate-Tunable Asymmetric Quantum Dots in Graphene-Based Heterostructures: Pure Valley Polarization and Confinement","authors":"A. Belayadi, Panagiotis Vasilopoulos","doi":"10.3390/c10020044","DOIUrl":"https://doi.org/10.3390/c10020044","url":null,"abstract":"We explore the possibility of attaining valley-dependent tunnelling and confinement using proximity-induced spin-orbit couplings (SOCs) in graphene-based heterostructures. We consider gate-tunable asymmetric quantum dots (AQDs) on graphene heterostructures and exhibiting a C3v and/or C6v symmetry. By employing a tight-binding model, we explicitly reveal a pure valley confinement and valley signal in AQDs by streaming the valley local density, leading to valley-charge separation in real space. The confinement of the valley quasi-bound states is sensitive to the locally induced SOCs and to the spatial distribution of the induced AQDs; it is also robust against on-site disorder. The adopted process of attaining a pure valley-Hall conductivity and confinement with zero charge currents is expected to provide more options towards valley-dependent electron optics.","PeriodicalId":503899,"journal":{"name":"C","volume":" 43","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141000002","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}
H. Armando, W. F. Giozza, L. A. Ribeiro Júnior, M. L. Pereira Júnior
Carbon-based materials have garnered significant attention since the groundbreaking synthesis of graphene. The exploration of novel 2D carbon allotropes has led to the discovery of materials with intrinsic properties distinct from graphene. Within this context, the biphenylene network (BPN) was successfully synthesized. In this study, we used molecular dynamics (MD) simulations with the Reactive Force Field (ReaxFF) to delve into the thermomechanical properties and fracture patterns of biphenylene-based nanotubes (BPN-NTs) exhibiting armchair (AC-BPN-NT) and zigzag (ZZ-BPN-NT) chiralities. Throughout the longitudinal deformation process, we observed significant morphological transformations preceding the structural fracture of the system. These transformations unfolded in distinct inelastic phases. In both cases, AC- and ZZ-BPN-NT, stress accumulation in four-membered rings led to the creation of octagonal structures; however, in AC, this occurs in the fracture region, subsequently causing the presence of nanopores. On the other hand, for ZZ-BPN-NT, stress accumulation in the rectangular rings occurred in bonds parallel to the deformation, with elongated octagonal structures. The Young’s modulus of these nanotubes ranged from 746 to 1259 GPa, with a melting point of around 4000 K. Our results also explore the influence of diameter and curvature, drawing comparisons with BPN monolayers.
自石墨烯的突破性合成以来，碳基材料一直备受关注。通过对新型二维碳同素异形体的探索，人们发现了具有不同于石墨烯固有特性的材料。在此背景下，联苯网络 (BPN) 被成功合成。在本研究中，我们利用分子动力学（MD）模拟和反应力场（ReaxFF）深入研究了联苯基纳米管（BPN-NTs）的热力学性质和断裂模式，这些纳米管分别呈现出臂形（AC-BPN-NT）和人字形（ZZ-BPN-NT）手性。在整个纵向变形过程中，我们观察到在系统结构断裂之前发生了显著的形态转变。这些转变以不同的非弹性阶段展开。在 AC 和 ZZ-BPN-NT 两种情况下，四元环中的应力累积都导致了八边形结构的产生；然而，在 AC 中，应力累积发生在断裂区域，随后导致了纳米孔的出现。另一方面，对于 ZZ-BPN-NT，矩形环中的应力累积发生在与变形平行的键上，形成了拉长的八角形结构。我们的结果还探讨了直径和曲率的影响，并与 BPN 单层进行了比较。
{"title":"On the Mechanical Properties and Fracture Patterns of Biphenylene-Based Nanotubes: A Reactive Molecular Dynamics Study","authors":"H. Armando, W. F. Giozza, L. A. Ribeiro Júnior, M. L. Pereira Júnior","doi":"10.3390/c10020042","DOIUrl":"https://doi.org/10.3390/c10020042","url":null,"abstract":"Carbon-based materials have garnered significant attention since the groundbreaking synthesis of graphene. The exploration of novel 2D carbon allotropes has led to the discovery of materials with intrinsic properties distinct from graphene. Within this context, the biphenylene network (BPN) was successfully synthesized. In this study, we used molecular dynamics (MD) simulations with the Reactive Force Field (ReaxFF) to delve into the thermomechanical properties and fracture patterns of biphenylene-based nanotubes (BPN-NTs) exhibiting armchair (AC-BPN-NT) and zigzag (ZZ-BPN-NT) chiralities. Throughout the longitudinal deformation process, we observed significant morphological transformations preceding the structural fracture of the system. These transformations unfolded in distinct inelastic phases. In both cases, AC- and ZZ-BPN-NT, stress accumulation in four-membered rings led to the creation of octagonal structures; however, in AC, this occurs in the fracture region, subsequently causing the presence of nanopores. On the other hand, for ZZ-BPN-NT, stress accumulation in the rectangular rings occurred in bonds parallel to the deformation, with elongated octagonal structures. The Young’s modulus of these nanotubes ranged from 746 to 1259 GPa, with a melting point of around 4000 K. Our results also explore the influence of diameter and curvature, drawing comparisons with BPN monolayers.","PeriodicalId":503899,"journal":{"name":"C","volume":"47 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141008978","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}
Activated carbon (AC) serves as extensively researched adsorbents, with numerous established methods for their preparation. This study originated from the hypothesis that compressing a hydrocarbon substance to create a densely compacted pellet, known as pelletizing, would enhance the development of porous features of the resulting AC. The anticipated enhancement is attributed to the rise in spatial proximity amidst HEC polymer chains within the bulk of the pellet, which facilitates aromatization both in extent and functionality. 2-Hydroxyethyl cellulose (HEC) pellets were prepared by adjusting the duration of load holding, aiming to increase the packing density of HEC polymer chains via creeping. The BET analysis of the resulting AC samples demonstrates the efficacy of compression on HEC pellets in enhancing their porous properties. The FE-SEM study revealed diverse AC surface morphologies that are associated with a set of specific pelletizing conditions. The 13C NMR spectroscopy for carbon skeletons, FT-IR spectroscopy for organic functionality, and XPS spectroscopy for surface composition collectively report the leverage of compression treatment before pyrolyzing HEC pellets. Furthermore, the assessment of hydrogen sulfide adsorption by the resulting AC samples revealed distinctive breakthrough curves, providing validation for the proposed compression effect.
活性炭（AC）是一种研究广泛的吸附剂，有许多成熟的制备方法。这项研究源于这样一个假设，即压缩碳氢化合物物质以形成致密的颗粒（称为造粒），将促进活性炭多孔特征的发展。预期的增强效果可归因于颗粒内部 HEC 聚合物链之间空间距离的增加，这有利于芳香化的程度和功能。制备 2-羟乙基纤维素（HEC）颗粒的方法是调整负载保持时间，目的是通过蠕变增加 HEC 聚合物链的堆积密度。对制备的 AC 样品进行的 BET 分析表明，对 HEC 颗粒的压缩能有效提高其多孔性。FE-SEM 研究揭示了与一系列特定造粒条件相关的不同 AC 表面形态。碳骨架的 13C NMR 光谱、有机功能的傅立叶变换红外光谱和表面成分的 XPS 光谱共同报告了热解 HEC 粒子前压缩处理的杠杆作用。此外，对所得 AC 样品进行的硫化氢吸附评估显示了独特的突破曲线，验证了所提出的压缩效应。
{"title":"Stimulating Mesoporous Characteristics of Activated Carbon through Pyrolysis of Compacted Hydroxyethyl Cellulose—A Showcase for H2S Removal","authors":"Fuxiang Chen, Liang Hong","doi":"10.3390/c10020043","DOIUrl":"https://doi.org/10.3390/c10020043","url":null,"abstract":"Activated carbon (AC) serves as extensively researched adsorbents, with numerous established methods for their preparation. This study originated from the hypothesis that compressing a hydrocarbon substance to create a densely compacted pellet, known as pelletizing, would enhance the development of porous features of the resulting AC. The anticipated enhancement is attributed to the rise in spatial proximity amidst HEC polymer chains within the bulk of the pellet, which facilitates aromatization both in extent and functionality. 2-Hydroxyethyl cellulose (HEC) pellets were prepared by adjusting the duration of load holding, aiming to increase the packing density of HEC polymer chains via creeping. The BET analysis of the resulting AC samples demonstrates the efficacy of compression on HEC pellets in enhancing their porous properties. The FE-SEM study revealed diverse AC surface morphologies that are associated with a set of specific pelletizing conditions. The 13C NMR spectroscopy for carbon skeletons, FT-IR spectroscopy for organic functionality, and XPS spectroscopy for surface composition collectively report the leverage of compression treatment before pyrolyzing HEC pellets. Furthermore, the assessment of hydrogen sulfide adsorption by the resulting AC samples revealed distinctive breakthrough curves, providing validation for the proposed compression effect.","PeriodicalId":503899,"journal":{"name":"C","volume":"29 s1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141008398","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}
Modern integrated circuits (ICs) take advantage of three-dimensional (3D) nanostructures in devices and interconnects to achieve high-speed and ultra-low-power performance. The choice of electrical insulation materials with excellent dielectric strength, electrical resistivity, strong mechanical strength, and high thermal conductivity becomes critical. Diamond possesses these properties and is recently recognized as a promising dielectric material for the fabrication of advanced ICs, which are sensitive to detrimental high-temperature processes. Therefore, a high-rate low-temperature deposition technique for large-grain, high-quality diamond films of the thickness of a few tens to a few hundred nanometers is desirable. The diamond growth rate by microwave plasma chemical vapor deposition (MPCVD) decreases rapidly with lowering substrate temperature. In addition, the thermal conductivity of non-diamond carbon is much lower than that of diamond. Furthermore, a small-grain diamond film suffers from poor thermal conductivity due to frequent phonon scattering at grain boundaries. This paper reports a novel MPCVD process aiming at high growth rate, large grain size, and high sp3/sp2 ratio for diamond films deposited on silicon. Graphite paste containing nanoscale graphite and oxy-hydrocarbon binder and solvent vaporizes and mixes with gas feeds of hydrogen, methane, and carbon dioxide to form plasma. Rapid diamond growth of diamond seeds at 450 °C by the plasma results in large-grained diamond films on silicon at a high deposition rate of 200 nm/h.
{"title":"Low-Temperature Deposition of Diamond Films by MPCVD with Graphite Paste Additive","authors":"Stephen Yang-En Guu, Fu-Cheng Lin, Yu-Sen Chien, Alen Jhang, Yon-Hua Tzeng","doi":"10.3390/c10020039","DOIUrl":"https://doi.org/10.3390/c10020039","url":null,"abstract":"Modern integrated circuits (ICs) take advantage of three-dimensional (3D) nanostructures in devices and interconnects to achieve high-speed and ultra-low-power performance. The choice of electrical insulation materials with excellent dielectric strength, electrical resistivity, strong mechanical strength, and high thermal conductivity becomes critical. Diamond possesses these properties and is recently recognized as a promising dielectric material for the fabrication of advanced ICs, which are sensitive to detrimental high-temperature processes. Therefore, a high-rate low-temperature deposition technique for large-grain, high-quality diamond films of the thickness of a few tens to a few hundred nanometers is desirable. The diamond growth rate by microwave plasma chemical vapor deposition (MPCVD) decreases rapidly with lowering substrate temperature. In addition, the thermal conductivity of non-diamond carbon is much lower than that of diamond. Furthermore, a small-grain diamond film suffers from poor thermal conductivity due to frequent phonon scattering at grain boundaries. This paper reports a novel MPCVD process aiming at high growth rate, large grain size, and high sp3/sp2 ratio for diamond films deposited on silicon. Graphite paste containing nanoscale graphite and oxy-hydrocarbon binder and solvent vaporizes and mixes with gas feeds of hydrogen, methane, and carbon dioxide to form plasma. Rapid diamond growth of diamond seeds at 450 °C by the plasma results in large-grained diamond films on silicon at a high deposition rate of 200 nm/h.","PeriodicalId":503899,"journal":{"name":"C","volume":"27 26","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140696047","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：