Yanrui Li, Linda Wang, Bo Zhan, Liangqing Zhang, Xiaolin Zhu, Xiang Gao
Sluggish charge separation dynamics resulting from the amorphous structure and the lack of driving force for graphitic carbon nitride (GCN) limits its highly effective CO2 photoreduction performance. Herein, a built-in electric field (BEF) was constructed for a well-designed CCN/Ni hybrid composed of crystalline carbon nitride (CCN) and metal complex, 2,2 '-bipyridine-4, 4' -dicarboxylic acids NiBr2 (dcabpyNiBr2), to steer the charge carrier separation and migration. The CCN/Ni hybrid was synthesized via solution-dispersion and molten-salt two-step approach, displaying an improved CO2 photoreduction to CO rate of 8.64 μmol∙g-1·h-1. In situ experimental results and theoretical simulations further investigated the relationships between BEF and photocatalytic activity. This work demonstrates an effective strategy to obtain high-efficiency photocatalytic systems by engineering crystal structure and constructing BEF.
由于石墨氮化碳（GCN）的无定形结构导致电荷分离动力学缓慢且缺乏驱动力，从而限制了其高效的二氧化碳光还原性能。在此，我们为一种精心设计的 CCN/Ni 混合物构建了内置电场（BEF），该混合物由结晶氮化碳（CCN）和金属复合物 2,2 '-联吡啶-4, 4' -二羧酸 NiBr2（dcabpyNiBr2）组成，用于引导电荷载流子的分离和迁移。通过溶液分散和熔盐两步法合成的 CCN/Ni 杂化物显示出更高的 CO2 光还原为 CO 的速率（8.64 μmol∙g-1-h-1）。现场实验结果和理论模拟进一步研究了 BEF 与光催化活性之间的关系。这项工作展示了通过晶体结构工程和构建 BEF 来获得高效光催化系统的有效策略。
{"title":"Constructing Nickel Complex/Crystalline Carbon Nitride Hybrid with a Built-in Electric Field for Boosting CO2 Photoreduction","authors":"Yanrui Li, Linda Wang, Bo Zhan, Liangqing Zhang, Xiaolin Zhu, Xiang Gao","doi":"10.1039/d4nr03586k","DOIUrl":"https://doi.org/10.1039/d4nr03586k","url":null,"abstract":"Sluggish charge separation dynamics resulting from the amorphous structure and the lack of driving force for graphitic carbon nitride (GCN) limits its highly effective CO2 photoreduction performance. Herein, a built-in electric field (BEF) was constructed for a well-designed CCN/Ni hybrid composed of crystalline carbon nitride (CCN) and metal complex, 2,2 '-bipyridine-4, 4' -dicarboxylic acids NiBr2 (dcabpyNiBr2), to steer the charge carrier separation and migration. The CCN/Ni hybrid was synthesized via solution-dispersion and molten-salt two-step approach, displaying an improved CO2 photoreduction to CO rate of 8.64 μmol∙g-1·h-1. In situ experimental results and theoretical simulations further investigated the relationships between BEF and photocatalytic activity. This work demonstrates an effective strategy to obtain high-efficiency photocatalytic systems by engineering crystal structure and constructing BEF.","PeriodicalId":92,"journal":{"name":"Nanoscale","volume":"95 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142601574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kun Hee Ye, Taeyoung Jeong, Seungjae Yoon, Dohyun Kim, Cheol Seong Hwang, Jung-Hae Choi
The in-plane tensile strain was reported to enhance the ferroelectricity of Hf1-xZrxO2 thin films by promoting the formation of the polar orthorhombic (PO-) phase. However, its origin remains yet to be identified unambiguously, although the stain-related thermodynamic stability variation was reported. This work explores the kinetic effects that have been overlooked to provide a precise answer to the problem, supplementing the thermodynamic calculations. The in-plane strain-dependent phase fractions were identified by calculating the relative influences of thermodynamic factor (Boltzmann distribution of free energies of polymorphs) and kinetic factor (transition rate between polymorphs using the Johnson-Mehl-Avrami equation). The monoclinic (M-) phase constitutes the ground state under almost all conditions. However, its formation is kinetically suppressed by the high activation barrier for the transition from the tetragonal (T-) phase. In contrast, the PO-phase formation is dominated by thermodynamic effects and is promoted under in-plane tensile strain due to the energetic stabilization of the PO-phase, while the T- to PO-phase transition is kinetically probable due to a low activation barrier. The in-plane tensile strain also lowers the activation barrier of TM, hence, the optimal tensile strain for the PO-phase formation varies by thermal conditions. The remanent polarization was calculated using spontaneous polarization and the PO-phase fraction. The in-plane tensile strain of 2~2.5% and moderate annealing at approximately 700 K are optimum for increasing ferroelectricity by 34% in Hf0.5Zr0.5O2 and 106% in ZrO2 along <111> orientation.
据报道，面内拉伸应变通过促进极性正交（PO-）相的形成，增强了 Hf1-xZrxO2 薄膜的铁电性。然而，尽管与染色相关的热力学稳定性变化已有报道，但其起源仍有待明确确定。这项研究探索了被忽视的动力学效应，为这一问题提供了精确的答案，并对热力学计算进行了补充。通过计算热力学因子（多晶体自由能的波尔兹曼分布）和动力学因子（使用约翰逊-梅尔-阿夫拉米方程计算多晶体之间的转变速率）的相对影响，确定了平面内随应变变化的相分数。在几乎所有条件下，单斜（M-）相都是基态。然而，由于从四方（T-）相过渡的活化势垒较高，其形成在动力学上受到抑制。与此相反，PO 相的形成主要受热力学效应的影响，在平面拉伸应变下，由于 PO 相的能量稳定化，PO 相的形成被促进，而 T 相向 PO 相的转变由于活化势垒较低，在动力学上是可能的。面内拉伸应变也降低了 TM 的活化势垒，因此 PO 相形成的最佳拉伸应变因热条件而异。利用自发极化和 PO 相分数计算了剩电位极化。在 Hf0.5Zr0.5O2 和 ZrO2 中，2~2.5% 的面内拉伸应变和大约 700 K 的适度退火是提高铁电性的最佳条件，分别提高了 34% 和 106%。
{"title":"Theoretical Understanding of the In-plane Tensile Strain Effects on Enhancing the Ferroelectric Performance of Hf0.5Zr0.5O2 and ZrO2 Thin Films","authors":"Kun Hee Ye, Taeyoung Jeong, Seungjae Yoon, Dohyun Kim, Cheol Seong Hwang, Jung-Hae Choi","doi":"10.1039/d4nr03333g","DOIUrl":"https://doi.org/10.1039/d4nr03333g","url":null,"abstract":"The in-plane tensile strain was reported to enhance the ferroelectricity of Hf1-xZrxO2 thin films by promoting the formation of the polar orthorhombic (PO-) phase. However, its origin remains yet to be identified unambiguously, although the stain-related thermodynamic stability variation was reported. This work explores the kinetic effects that have been overlooked to provide a precise answer to the problem, supplementing the thermodynamic calculations. The in-plane strain-dependent phase fractions were identified by calculating the relative influences of thermodynamic factor (Boltzmann distribution of free energies of polymorphs) and kinetic factor (transition rate between polymorphs using the Johnson-Mehl-Avrami equation). The monoclinic (M-) phase constitutes the ground state under almost all conditions. However, its formation is kinetically suppressed by the high activation barrier for the transition from the tetragonal (T-) phase. In contrast, the PO-phase formation is dominated by thermodynamic effects and is promoted under in-plane tensile strain due to the energetic stabilization of the PO-phase, while the T- to PO-phase transition is kinetically probable due to a low activation barrier. The in-plane tensile strain also lowers the activation barrier of TM, hence, the optimal tensile strain for the PO-phase formation varies by thermal conditions. The remanent polarization was calculated using spontaneous polarization and the PO-phase fraction. The in-plane tensile strain of 2~2.5% and moderate annealing at approximately 700 K are optimum for increasing ferroelectricity by 34% in Hf0.5Zr0.5O2 and 106% in ZrO2 along <111> orientation.","PeriodicalId":92,"journal":{"name":"Nanoscale","volume":"33 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142599893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Exotic polar topologies such as polar skyrmions have been widely observed in the ferroelectric superlattice system. The dynamic motion of the polar skyrmion under external forces holds promise for applications in advanced electronic devices such as race-track memory. Meanwhile, the polar skyrmion motion has proven to be challenging due to the strong skyrmion-skyrmion interaction and a lack of a mechanism similar to the spin-transfer torque. In this study, we have developed a nudged elastic band (NEB) method to quantify the polar skyrmion motion barrier along a specific trajectory. It is indicated that the skyrmion motion barrier can be significantly reduced with the reduction of the periodicity to 8 u.c., due to the large reduction of the skyrmion size. Moreover, this barrier can also be greatly reduced with a small external electric potential. Following the analysis, we further performed phase-field simulation to verify the collective motion of the polar skyrmion. We have demonstrated the skyrmion motion by applying a 5 μN mechanical force using a blame-shaped indenter with a periodicity of 8 unit cells, under an external applied voltage of 1.5 V. This study further paves the way for the design of the polar skyrmion-based electronic devices.
{"title":"Quantifying the polar skyrmion motion barrier in an oxide heterostructure","authors":"Lizhe Hu, Yuhui Huang, Yong Jun Wu, Zijian Hong","doi":"10.1039/d4nr03686g","DOIUrl":"https://doi.org/10.1039/d4nr03686g","url":null,"abstract":"Exotic polar topologies such as polar skyrmions have been widely observed in the ferroelectric superlattice system. The dynamic motion of the polar skyrmion under external forces holds promise for applications in advanced electronic devices such as race-track memory. Meanwhile, the polar skyrmion motion has proven to be challenging due to the strong skyrmion-skyrmion interaction and a lack of a mechanism similar to the spin-transfer torque. In this study, we have developed a nudged elastic band (NEB) method to quantify the polar skyrmion motion barrier along a specific trajectory. It is indicated that the skyrmion motion barrier can be significantly reduced with the reduction of the periodicity to 8 u.c., due to the large reduction of the skyrmion size. Moreover, this barrier can also be greatly reduced with a small external electric potential. Following the analysis, we further performed phase-field simulation to verify the collective motion of the polar skyrmion. We have demonstrated the skyrmion motion by applying a 5 μN mechanical force using a blame-shaped indenter with a periodicity of 8 unit cells, under an external applied voltage of 1.5 V. This study further paves the way for the design of the polar skyrmion-based electronic devices.","PeriodicalId":92,"journal":{"name":"Nanoscale","volume":"43 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142599898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anton Senenko, Alexander Anatolievich Marchenko, Oleksandr Kurochkin, Oleksiy Kapitanchuk, Mykola Kravets, Vassili Nazarenko, Volodymyr Sashuk
We present the spontaneous isomerization of donor-acceptor Stenhouse adducts anchored onto a gold surface, visualized using scanning tunneling spectroscopy. Our investigation reveals a palette of molecular arrangements, including those with ferroelectric-like ordering, evolving over time into a fine pattern consisting of both open and closed forms of the photoswitch.
{"title":"Spontaneous switching and fine structure of donor-acceptor Stenhouse adducts on Au(111)","authors":"Anton Senenko, Alexander Anatolievich Marchenko, Oleksandr Kurochkin, Oleksiy Kapitanchuk, Mykola Kravets, Vassili Nazarenko, Volodymyr Sashuk","doi":"10.1039/d4nr03942d","DOIUrl":"https://doi.org/10.1039/d4nr03942d","url":null,"abstract":"We present the spontaneous isomerization of donor-acceptor Stenhouse adducts anchored onto a gold surface, visualized using scanning tunneling spectroscopy. Our investigation reveals a palette of molecular arrangements, including those with ferroelectric-like ordering, evolving over time into a fine pattern consisting of both open and closed forms of the photoswitch.","PeriodicalId":92,"journal":{"name":"Nanoscale","volume":"95 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142599894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jeongmin Kim, Seonhye Youn, Damin Lee, Chan Woong Kim, Hongjae Moon, Seok-Hwan Chung, Hoyoung Kim, Dong Hwan Kim, Sumin Kim, Jong Wook Roh, Joonho Bang, Wooyoung Lee
Two-dimensional (2D) metallic transition metal dichalcogenides (TMDCs) have attracted extensive interest in various fields owing to their unique electronic properties. However, studies on their transport properties and the modulation of these properties based on their band structure are limited. Herein, we studied the transport phenomena in 2D metallic 2H-NbSe2 using experimental and theoretical approaches. The transport properties, including electrical conductivity (σ) and Seebeck coefficient (S), of mechanically exfoliated 2H-NbSe2 nanosheets were measured. We observed field effect-dependent variations in σ and S of the 2H-NbSe2 nanosheets. Theoretical calculations of the electronic band structures and estimations of the transport properties of 2D 2H-NbSe2 crystals were conducted to verify and explain the experimental results. The superconducting transition temperature of the exfoliated NbSe2 nanosheets validated the reliability of the sample preparation procedures and indicated the high quality of the samples. Our findings provide a basis for understanding the electrical properties of metallic TMDCs intended for various applications.
{"title":"Electrical transport phenomena in two-dimensional metallic 2H-NbSe2: an experimental and theoretical study","authors":"Jeongmin Kim, Seonhye Youn, Damin Lee, Chan Woong Kim, Hongjae Moon, Seok-Hwan Chung, Hoyoung Kim, Dong Hwan Kim, Sumin Kim, Jong Wook Roh, Joonho Bang, Wooyoung Lee","doi":"10.1039/d4nr03369h","DOIUrl":"https://doi.org/10.1039/d4nr03369h","url":null,"abstract":"Two-dimensional (2D) metallic transition metal dichalcogenides (TMDCs) have attracted extensive interest in various fields owing to their unique electronic properties. However, studies on their transport properties and the modulation of these properties based on their band structure are limited. Herein, we studied the transport phenomena in 2D metallic 2H-NbSe<small><sub>2</sub></small> using experimental and theoretical approaches. The transport properties, including electrical conductivity (<em>σ</em>) and Seebeck coefficient (<em>S</em>), of mechanically exfoliated 2H-NbSe<small><sub>2</sub></small> nanosheets were measured. We observed field effect-dependent variations in <em>σ</em> and <em>S</em> of the 2H-NbSe<small><sub>2</sub></small> nanosheets. Theoretical calculations of the electronic band structures and estimations of the transport properties of 2D 2H-NbSe<small><sub>2</sub></small> crystals were conducted to verify and explain the experimental results. The superconducting transition temperature of the exfoliated NbSe<small><sub>2</sub></small> nanosheets validated the reliability of the sample preparation procedures and indicated the high quality of the samples. Our findings provide a basis for understanding the electrical properties of metallic TMDCs intended for various applications.","PeriodicalId":92,"journal":{"name":"Nanoscale","volume":"11 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142599895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Binary superlattices (BNSLs) with unique configurations are of great interest, attributing to the interaction between two kinds of nanoparticles, providing potential applications in sensing, electronic and optical fields. Here, polystyrene (PS) tethered spherical gold nanoparticles (AuNPs) with two core diameters spontaneously assembled into BNSLs via emulsion-confined self-assembly. The BNSLs with specific stoichiometry and interparticle gap of the NPs are prepared by tuning the number and size ratios of the two types of NPs. Moreover, after introducing long ligands, the arrangement of final superstructures can be tuned from separated into macroscopic phase separation or uniform distribution, relying on the interaction between polymer chains tethered on the AuNPs. Finally, PS-tethered AuNPs provide more possibilities for fabricating multifunctional BNSLs.
{"title":"Effect of number ratio and size ratio on the formation of binary superlattices assembled by two-sized polymer-tethered spherical nanoparticles","authors":"Jinlan Li, Xin Yu, Jianing Zhang, Jing Jin, Yanxiong Pan, Xiangling Ji, Wei Jiang","doi":"10.1039/d4nr04032e","DOIUrl":"https://doi.org/10.1039/d4nr04032e","url":null,"abstract":"Binary superlattices (BNSLs) with unique configurations are of great interest, attributing to the interaction between two kinds of nanoparticles, providing potential applications in sensing, electronic and optical fields. Here, polystyrene (PS) tethered spherical gold nanoparticles (AuNPs) with two core diameters spontaneously assembled into BNSLs via emulsion-confined self-assembly. The BNSLs with specific stoichiometry and interparticle gap of the NPs are prepared by tuning the number and size ratios of the two types of NPs. Moreover, after introducing long ligands, the arrangement of final superstructures can be tuned from separated into macroscopic phase separation or uniform distribution, relying on the interaction between polymer chains tethered on the AuNPs. Finally, PS-tethered AuNPs provide more possibilities for fabricating multifunctional BNSLs.","PeriodicalId":92,"journal":{"name":"Nanoscale","volume":"15 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142599899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
As the core component of direct methanol fuel cell, the catalyst layer plays the key role of material, proton and electron transport channels. However, due to the complexity of its system, optimizing its performance requires a large number of experiments and high costs. In this paper, finite element simulation combined with machine learning model is constructed to accelerate power density prediction and evaluate the influence of catalyst layer parameters on the maximum power density of direct methanol fuel cell. We built a fuel cell simulation model corresponding to different parameters, obtaining a database of more than 200 sets of 19 eigenvalues, and then used different machine learning models for training and prediction. Finally, three tree integration methods were selected to rank the importance of 19 characteristic parameters. In addition, we performed a high-throughput screening of 200,000 different parameter combinations based on Sequential Model-Based Algorithm Configuration. We selected the top 10 parameter combinations with high expected improvement score into numerical simulation model. The results show that a majority of the polarization curves obtained from the top combinations exceed the maximum power density of the original database. This method greatly saves the time of collecting fuel cell data for experiments and speeds up the parameter optimization process.
{"title":"Electrode Informatics Accelerated Optimization for Catalyst Layer Key Parameters in Direct Methanol Fuel Cells","authors":"Lishou Ban, Danyang Huang, Yanyi Liu, Pengcheng Liu, Xihui Bian, Kaili Wang, Yifan Liu, Xijun Liu, Jia He","doi":"10.1039/d4nr03026e","DOIUrl":"https://doi.org/10.1039/d4nr03026e","url":null,"abstract":"As the core component of direct methanol fuel cell, the catalyst layer plays the key role of material, proton and electron transport channels. However, due to the complexity of its system, optimizing its performance requires a large number of experiments and high costs. In this paper, finite element simulation combined with machine learning model is constructed to accelerate power density prediction and evaluate the influence of catalyst layer parameters on the maximum power density of direct methanol fuel cell. We built a fuel cell simulation model corresponding to different parameters, obtaining a database of more than 200 sets of 19 eigenvalues, and then used different machine learning models for training and prediction. Finally, three tree integration methods were selected to rank the importance of 19 characteristic parameters. In addition, we performed a high-throughput screening of 200,000 different parameter combinations based on Sequential Model-Based Algorithm Configuration. We selected the top 10 parameter combinations with high expected improvement score into numerical simulation model. The results show that a majority of the polarization curves obtained from the top combinations exceed the maximum power density of the original database. This method greatly saves the time of collecting fuel cell data for experiments and speeds up the parameter optimization process.","PeriodicalId":92,"journal":{"name":"Nanoscale","volume":"1 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142598406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study investigates the effects of graphene content and applied press on electrical and thermal conductivities of graphite/polyaniline (GP) and graphite/graphene/polyaniline (GGP) composites which were produced by using direct mixing method. Based on electrical and thermal conductivity results, 14 wt. % graphene content was found out to be the crucial threshold, beyond which extra graphene additions exhibit different behavior in pressed and unpressed samples. While the electrical conductivity of unpressed samples increase up to 14 wt. % graphene addition, the thermal conductivity increases further after 14 wt. % graphene addition. The addition of graphene induces notable changes in electronic configurations of quinoid and benzenoid rings, as evidenced by ATR-FT-IR spectroscopy. Based on XPS data, the addition of graphene into graphite/PANI-CSA matrix affects electronic distribution and charge transfer mechanisms within GGP composites, particularly showing the impact of graphene addition on the electronic structure of PANI-CSA in GGP-14 527 MPa sample. Importantly, the interlocking of graphene and graphite layers observed in GGP-14 sample pressed at 527 MPa according to Raman and XRD data, leads to enhanced thermal (2253 W m⁻¹K⁻¹), and electrical (210 S cm⁻¹) conductivity. The interlocked configuration of graphene and graphite in GGP-14 527 MPa facilitates efficient electron and phonon flow throughout hexagonal C=C rings and partially charged nitrogen and oxygen atoms of PANI-CSA. In future works, the concept of interlocked graphene and graphite layers can be used to further enhance thermal and electrical properties in thermoelectric material applications.
{"title":"Exploring Graphene's Impact on Graphite/PANI Matrix Composites: High-Press Fabrication and Enhanced Thermal-Electrical Properties","authors":"Murat OZLEK, Merve Sehnaz Akbulut, Engin Burgaz","doi":"10.1039/d4nr03171g","DOIUrl":"https://doi.org/10.1039/d4nr03171g","url":null,"abstract":"This study investigates the effects of graphene content and applied press on electrical and thermal conductivities of graphite/polyaniline (GP) and graphite/graphene/polyaniline (GGP) composites which were produced by using direct mixing method. Based on electrical and thermal conductivity results, 14 wt. % graphene content was found out to be the crucial threshold, beyond which extra graphene additions exhibit different behavior in pressed and unpressed samples. While the electrical conductivity of unpressed samples increase up to 14 wt. % graphene addition, the thermal conductivity increases further after 14 wt. % graphene addition. The addition of graphene induces notable changes in electronic configurations of quinoid and benzenoid rings, as evidenced by ATR-FT-IR spectroscopy. Based on XPS data, the addition of graphene into graphite/PANI-CSA matrix affects electronic distribution and charge transfer mechanisms within GGP composites, particularly showing the impact of graphene addition on the electronic structure of PANI-CSA in GGP-14 527 MPa sample. Importantly, the interlocking of graphene and graphite layers observed in GGP-14 sample pressed at 527 MPa according to Raman and XRD data, leads to enhanced thermal (2253 W m⁻¹K⁻¹), and electrical (210 S cm⁻¹) conductivity. The interlocked configuration of graphene and graphite in GGP-14 527 MPa facilitates efficient electron and phonon flow throughout hexagonal C=C rings and partially charged nitrogen and oxygen atoms of PANI-CSA. In future works, the concept of interlocked graphene and graphite layers can be used to further enhance thermal and electrical properties in thermoelectric material applications.","PeriodicalId":92,"journal":{"name":"Nanoscale","volume":"14 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142598410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We report a lead-free copper-based halide perovskite gas sensor to detect ammonia gas at ambient temperature. The sensor uses methylammonium copper bromide as the active material and can trace ammonia by both visual color change method as well as electrical readout. The maximum calibrated sensitivity based on the optical response of the sensor is ∼95% on exposure to 10 ppm ammonia gas, which is the best among the colorimetric sensors using halide perovskites. The sensor can be operated at 0.5 V bias with an output current of ∼12 μA at 50 ppm ammonia gas exposure, making our device compatible with low-power gas sensors. Also, we studied the degradation mechanism by subjecting the MA2CuBr4 film over ammonia exposure cycles. We found that there are two factors responsible for the degradation of the sensor: (i) loss of methylamine gas due to formation of NH4Br, and (ii) reduction of Cu2+ to Cu+. Increasing the proportion of MABr in the system, increases the material’s tolerance to ammonia exposure by solving the methylamine gas escape problem. Further we have shown that the stability of the device can be enhanced by depositing porous polymethylmethacrylate over the copper perovskite.
{"title":"Unraveling the Ammonia Sensing Behavior and Degradation Pathways of Novel Lead-Free MA2CuBr4 based Ammonia Sensor","authors":"Abinash Tiwari, Arjumand Mir, Aswani Yella","doi":"10.1039/d4nr02943g","DOIUrl":"https://doi.org/10.1039/d4nr02943g","url":null,"abstract":"We report a lead-free copper-based halide perovskite gas sensor to detect ammonia gas at ambient temperature. The sensor uses methylammonium copper bromide as the active material and can trace ammonia by both visual color change method as well as electrical readout. The maximum calibrated sensitivity based on the optical response of the sensor is ∼95% on exposure to 10 ppm ammonia gas, which is the best among the colorimetric sensors using halide perovskites. The sensor can be operated at 0.5 V bias with an output current of ∼12 μA at 50 ppm ammonia gas exposure, making our device compatible with low-power gas sensors. Also, we studied the degradation mechanism by subjecting the MA2CuBr4 film over ammonia exposure cycles. We found that there are two factors responsible for the degradation of the sensor: (i) loss of methylamine gas due to formation of NH4Br, and (ii) reduction of Cu2+ to Cu+. Increasing the proportion of MABr in the system, increases the material’s tolerance to ammonia exposure by solving the methylamine gas escape problem. Further we have shown that the stability of the device can be enhanced by depositing porous polymethylmethacrylate over the copper perovskite.","PeriodicalId":92,"journal":{"name":"Nanoscale","volume":"4 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142598407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The shrinkage phenomenon of UV-NIL resist during photocuring is still regarded as an important problem hindering the wide application of UV-NIL technology. We designed four degradable UV-NIL resists with low volume shrinkage rate based on acrylic anhydride. Acrylate provided quickly UV curing ability and the resists were completely cured under 365 nm UV light for 10 seconds. The anhydride group provided degradation ability, causing the cured resists completely dissolved in alkaline developer. Introducing rings in the molecular structure could compensate for volume shrinkage by ring-opening, and the volume shrinkage rate of resists was below 4%. The cured resists showed good thermal stability with decomposition temperature higher than 150 ℃. The UV-NIL resists demonstrated good pattern replication ability and distinct patterns with 100 nm resolution were obtained. The prepared UV-NIL resists were expected to play a role in the manufacturing of semiconductors, solar cells, displays, sensors, and other devices in the future.
{"title":"Low Volume Shrinkage Alkaline Degradable UV Nanoimprint Lithography Resists Based on Acrylic Anhydride","authors":"Chuan Zhe Zhao, Ya-Juan Cai, Yi-Xing Sun, Ya-Ge Wu, Kexiao Sang, Ting Yue, Zihao Yang, Jinggang Gai","doi":"10.1039/d4nr03291h","DOIUrl":"https://doi.org/10.1039/d4nr03291h","url":null,"abstract":"The shrinkage phenomenon of UV-NIL resist during photocuring is still regarded as an important problem hindering the wide application of UV-NIL technology. We designed four degradable UV-NIL resists with low volume shrinkage rate based on acrylic anhydride. Acrylate provided quickly UV curing ability and the resists were completely cured under 365 nm UV light for 10 seconds. The anhydride group provided degradation ability, causing the cured resists completely dissolved in alkaline developer. Introducing rings in the molecular structure could compensate for volume shrinkage by ring-opening, and the volume shrinkage rate of resists was below 4%. The cured resists showed good thermal stability with decomposition temperature higher than 150 ℃. The UV-NIL resists demonstrated good pattern replication ability and distinct patterns with 100 nm resolution were obtained. The prepared UV-NIL resists were expected to play a role in the manufacturing of semiconductors, solar cells, displays, sensors, and other devices in the future.","PeriodicalId":92,"journal":{"name":"Nanoscale","volume":"71 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142598382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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