Federico Loi, Luca Bignardi, Deborah Perco, Andrea Berti, Paolo Lacovig, Silvano Lizzit, Aras Kartouzian, Ulrich Heiz, Dario Alfè, Alessandro Baraldi
The concept of preferential atomic and molecular adsorption site is of primary relevance in heterogeneous catalysis. In the case of ultrasmall size-selected clusters, distinguishing the role played by each atom in a reaction is extremely challenging due to their reduced size and peculiar structures. Herein, it is revealed how the inequivalent atoms composing graphene-supported Pt12 and Pt13 clusters behave differently in the photoinduced dissociation of O2, with only those in the uppermost layer of the clusters being involved in the reaction. In this process, the epitaxial graphene support plays a fundamental active role: its corrugation and pinning induced by the presence of the clusters are crucial for defining the preferential adsorption site on the Pt atomic agglomerates, facilitating the lateral diffusion of physisorbed oxygen at a distance that induces its selective adsorption in the topmost layer of the clusters, and inducing an inhomogeneous charge distribution within the clusters which directly affects the O2 adsorption. The inhomogeneous oxidation of the clusters is resolved by means of synchrotron-based X-ray photoelectron spectroscopy and supported by ab initio density functional theory calculations. The possibility to identify the active sites on Pt clusters induced by cluster–support interactions has the potential to enhance the experimentally supported design of nanocatalysts.
{"title":"Unveiling Inequality of Atoms in Ultrasmall Pt Clusters: Oxygen Adsorption Limited to the Uppermost Atomic Layer","authors":"Federico Loi, Luca Bignardi, Deborah Perco, Andrea Berti, Paolo Lacovig, Silvano Lizzit, Aras Kartouzian, Ulrich Heiz, Dario Alfè, Alessandro Baraldi","doi":"10.1002/sstr.202400250","DOIUrl":"https://doi.org/10.1002/sstr.202400250","url":null,"abstract":"The concept of preferential atomic and molecular adsorption site is of primary relevance in heterogeneous catalysis. In the case of ultrasmall size-selected clusters, distinguishing the role played by each atom in a reaction is extremely challenging due to their reduced size and peculiar structures. Herein, it is revealed how the inequivalent atoms composing graphene-supported Pt<sub>12</sub> and Pt<sub>13</sub> clusters behave differently in the photoinduced dissociation of O<sub>2</sub>, with only those in the uppermost layer of the clusters being involved in the reaction. In this process, the epitaxial graphene support plays a fundamental active role: its corrugation and pinning induced by the presence of the clusters are crucial for defining the preferential adsorption site on the Pt atomic agglomerates, facilitating the lateral diffusion of physisorbed oxygen at a distance that induces its selective adsorption in the topmost layer of the clusters, and inducing an inhomogeneous charge distribution within the clusters which directly affects the O<sub>2</sub> adsorption. The inhomogeneous oxidation of the clusters is resolved by means of synchrotron-based X-ray photoelectron spectroscopy and supported by ab initio density functional theory calculations. The possibility to identify the active sites on Pt clusters induced by cluster–support interactions has the potential to enhance the experimentally supported design of nanocatalysts.","PeriodicalId":21841,"journal":{"name":"Small Structures","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218399","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}
Narges Ahmadi, Dong Yun Kim, Seung Soo Shin, Sneha Daradmare, Jong-Man Kim, Bum Jun Park
Polydiacetylenes (PDA) are highly regarded for their unique colorimetric and fluorescent responses, making them ideal for sensor development. Despite their potential, conventional methods for fabricating biocompatible PDA-encapsulated hydrogel sensor beads often fail to offer precise control over bead size and morphology. This study introduces a coflow gas-shearing microfluidic system that effectively overcomes these limitations, enabling the controlled production of polydiacetylene/alginate (PDA/Alg) and polydiacetylene/polydimethylsiloxane/alginate (PDA/PDMS/Alg) microbeads. Through systematic variation of gas pressure, liquid flow rates, and nozzle sizes, the mechanisms of droplet breakup and generation are explored. This process is validated through numerical modeling based on the Weber number, which enhances our understanding of droplet size distribution and flow regimes. The solvatochromic properties of PDA/Alg microbeads are assessed, highlighting their potential as polar solvent sensors and discussing the solvatochromic mechanism in terms of intermolecular interactions and the dissolution of unpolymerized monomers. Additionally, PDA/PDMS/Alg microbeads exhibit a semireversible thermochromic response under repeated cycles of heating, cooling, and UV exposure. This response is attributed to the formation of new PDA domains inside the PDMS phase upon UV exposure onto the red-phase microbeads. Overall, this study successfully demonstrates a straightforward and effective microfluidic approach for producing well-defined stimulus-responsive PDA–hydrogel microbeads.
{"title":"Gas-Shearing Microfluidic Fabrication of Polydiacetylene–Alginate Colorimetric Sensor Beads","authors":"Narges Ahmadi, Dong Yun Kim, Seung Soo Shin, Sneha Daradmare, Jong-Man Kim, Bum Jun Park","doi":"10.1002/sstr.202400340","DOIUrl":"https://doi.org/10.1002/sstr.202400340","url":null,"abstract":"Polydiacetylenes (PDA) are highly regarded for their unique colorimetric and fluorescent responses, making them ideal for sensor development. Despite their potential, conventional methods for fabricating biocompatible PDA-encapsulated hydrogel sensor beads often fail to offer precise control over bead size and morphology. This study introduces a coflow gas-shearing microfluidic system that effectively overcomes these limitations, enabling the controlled production of polydiacetylene/alginate (PDA/Alg) and polydiacetylene/polydimethylsiloxane/alginate (PDA/PDMS/Alg) microbeads. Through systematic variation of gas pressure, liquid flow rates, and nozzle sizes, the mechanisms of droplet breakup and generation are explored. This process is validated through numerical modeling based on the Weber number, which enhances our understanding of droplet size distribution and flow regimes. The solvatochromic properties of PDA/Alg microbeads are assessed, highlighting their potential as polar solvent sensors and discussing the solvatochromic mechanism in terms of intermolecular interactions and the dissolution of unpolymerized monomers. Additionally, PDA/PDMS/Alg microbeads exhibit a semireversible thermochromic response under repeated cycles of heating, cooling, and UV exposure. This response is attributed to the formation of new PDA domains inside the PDMS phase upon UV exposure onto the red-phase microbeads. Overall, this study successfully demonstrates a straightforward and effective microfluidic approach for producing well-defined stimulus-responsive PDA–hydrogel microbeads.","PeriodicalId":21841,"journal":{"name":"Small Structures","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218330","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}
Alkaline zinc-based batteries (AZBs) can yield higher operating voltages due to a more negative electrode potential of zinc metal in alkaline electrolytes compared with neutral electrolytes, delivering high energy density in practical manufacturing applications. However, AZBs also exhibit more pronounced problems due to severe corrosion of the zinc anode by the strongly alkaline electrolyte environment. Combined with the reaction mechanism of alkaline zinc batteries, negatively charged carbon dots are innovatively used to construct a barrier with both physical and chemical effects. Zinc anode exposure to electrolyte is reduced by superior barrier, which assures transmission of zinc ions rather than zincate ions through electrostatic force balance, thus improving the distribution of the electric field for zinc ion deposition as well as avoiding accumulation of zincate ions at the interface. The number of harmful dendrite formation was found to be significantly suppressed by in situ optical microscopy. When coupled with silver oxide cathode for testing, the assembled silver-zinc battery results in a significant enhancement in its cyclic life. It is believed that this study will propel the development of zinc anode in alkaline batteries and provide new insights for their application.
{"title":"Negative Charge Carbon Dots Manufacturing Electrostatic Shielding Layer for Stable Zinc Anode","authors":"Kai Wang, Jinqiang Gao, Huaxin Liu, Weishun Jian, Jiangnan Huang, XinYu Hu, Siyuan Lai, Yafei Li, Guoqiang Zou, Hongshuai Hou, Wentao Deng, Xiaobo Ji","doi":"10.1002/sstr.202400343","DOIUrl":"https://doi.org/10.1002/sstr.202400343","url":null,"abstract":"Alkaline zinc-based batteries (AZBs) can yield higher operating voltages due to a more negative electrode potential of zinc metal in alkaline electrolytes compared with neutral electrolytes, delivering high energy density in practical manufacturing applications. However, AZBs also exhibit more pronounced problems due to severe corrosion of the zinc anode by the strongly alkaline electrolyte environment. Combined with the reaction mechanism of alkaline zinc batteries, negatively charged carbon dots are innovatively used to construct a barrier with both physical and chemical effects. Zinc anode exposure to electrolyte is reduced by superior barrier, which assures transmission of zinc ions rather than zincate ions through electrostatic force balance, thus improving the distribution of the electric field for zinc ion deposition as well as avoiding accumulation of zincate ions at the interface. The number of harmful dendrite formation was found to be significantly suppressed by in situ optical microscopy. When coupled with silver oxide cathode for testing, the assembled silver-zinc battery results in a significant enhancement in its cyclic life. It is believed that this study will propel the development of zinc anode in alkaline batteries and provide new insights for their application.","PeriodicalId":21841,"journal":{"name":"Small Structures","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218209","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}
Zhenliang Li, Yujian Rao, Zhehan Wang, Tuo Zhang, Guodong Wu, Litao Sun, Yuan Ren, Li Tao
Two-dimensional (2D) transition metal dichalcogenides (TMDs) are widely used in interfacial reactions and electronic devices due to their tunable bandgap and high efficiency of carrier transport. However, the lack of fully exposed active sites in bulk samples or stacked nanosheets leads to limited performances. In this work, a general method is developed to construct ordered mesoporous TMDs/metal oxides (OM-TMDs/MOs) heterostructures, including WS<sub>2</sub>/WO<sub>3</sub>, WSe<sub>2</sub>/WO<sub>3</sub>, WTe<sub>2</sub>/WO<sub>3</sub>, MoS<sub>2</sub>/MoO<sub>3</sub>, and V<sub>3</sub>S<sub>4</sub>/V<sub>2</sub>O<sub>3</sub>, through one-step thermal sulfurization (selenidation/tellurization) of self-assembled amphiphilic block copolymer/polyoxometalates clusters nanocomposites with ordered mesostructures. The OM-TMDs/MOs possess highly OM structures with high specific surface area, large pore size, and rich active edge sites in the frameworks of heterostructures. The chemiresistive gas sensor based on OM-WS<sub>2</sub>/WO<sub>3</sub> shows excellent NO<sub>2</sub>-sensing performances at room temperature, with high sensitivity, ultrahigh selectivity (<span data-altimg="/cms/asset/a3e5cd6e-ac04-41a3-b6e2-cce80c9d4d74/sstr202400376-math-0001.png"></span><mjx-container ctxtmenu_counter="3" ctxtmenu_oldtabindex="1" jax="CHTML" role="application" sre-explorer- style="font-size: 103%; position: relative;" tabindex="0"><mjx-math aria-hidden="true" location="graphic/sstr202400376-math-0001.png"><mjx-semantics><mjx-mrow><mjx-msub data-semantic-children="0,3" data-semantic- data-semantic-role="latinletter" data-semantic-speech="upper S Subscript NO Sub Subscript 2" data-semantic-type="subscript"><mjx-mi data-semantic-annotation="clearspeak:simple" data-semantic-font="italic" data-semantic- data-semantic-parent="4" data-semantic-role="latinletter" data-semantic-type="identifier"><mjx-c></mjx-c></mjx-mi><mjx-script style="vertical-align: -0.15em; margin-left: -0.032em;"><mjx-mrow size="s"><mjx-msub data-semantic-children="1,2" data-semantic- data-semantic-parent="4" data-semantic-role="unknown" data-semantic-type="subscript"><mjx-mrow><mjx-mtext data-semantic-annotation="clearspeak:unit" data-semantic-font="normal" data-semantic- data-semantic-parent="3" data-semantic-role="unknown" data-semantic-type="text"><mjx-c></mjx-c><mjx-c></mjx-c></mjx-mtext></mjx-mrow><mjx-script style="vertical-align: -0.15em;"><mjx-mn data-semantic-annotation="clearspeak:simple" data-semantic-font="normal" data-semantic- data-semantic-parent="3" data-semantic-role="integer" data-semantic-type="number" size="s"><mjx-c></mjx-c></mjx-mn></mjx-script></mjx-msub></mjx-mrow></mjx-script></mjx-msub></mjx-mrow></mjx-semantics></mjx-math><mjx-assistive-mml display="inline" unselectable="on"><math altimg="urn:x-wiley:26884062:media:sstr202400376:sstr202400376-math-0001" display="inline" location="graphic/sstr202400376-math-0001.png" xmlns="http://www.w3.org/1998/Math/MathML"><semantics><
二维（2D）过渡金属二掺杂物（TMDs）具有可调带隙和高载流子传输效率，因此被广泛应用于界面反应和电子器件中。然而，由于块状样品或堆叠纳米片中缺乏完全暴露的活性位点，导致其性能有限。本研究开发了一种通用方法来构建有序介孔 TMDs/金属氧化物（OM-TMDs/MOs）异质结构，包括 WS2/WO3、WSe2/WO3、WTe2/WO3、MoS2/MoO3 和 V3S4/V2O3、通过对具有有序介观结构的自组装两亲嵌段共聚物/聚氧化金属簇纳米复合材料进行一步热硫化（硒化/高纯化）。OM-TMDs/MOs 具有高度 OM 结构、高比表面积、大孔径以及异质结构框架中丰富的活性边缘位点。基于 OM-WS2/WO3 的化学电阻式气体传感器在室温下显示出优异的二氧化氮传感性能，具有高灵敏度、超高选择性（SNO2$S_{left(text{NO}right)_{2}}$/Sgas >20）和快速响应速度（6 s）。理论研究表明，WS2/WO3 异质结构和 WS2 边缘位点对 NO2 分子的强大吸附能力以及它们之间的高电荷转移有助于提高传感器的选择性和灵敏度。这种通用方法为合成基于 OM TMDs 的纳米材料提供了新的策略，在电子器件、催化、储能和转换等各种应用中显示出巨大的潜力。
{"title":"Universal Synthesis of Core–Shell-Structured Ordered Mesoporous Transition Metal Dichalcogenides/Metal Oxides Heterostructures with Active Edge Sites","authors":"Zhenliang Li, Yujian Rao, Zhehan Wang, Tuo Zhang, Guodong Wu, Litao Sun, Yuan Ren, Li Tao","doi":"10.1002/sstr.202400376","DOIUrl":"https://doi.org/10.1002/sstr.202400376","url":null,"abstract":"Two-dimensional (2D) transition metal dichalcogenides (TMDs) are widely used in interfacial reactions and electronic devices due to their tunable bandgap and high efficiency of carrier transport. However, the lack of fully exposed active sites in bulk samples or stacked nanosheets leads to limited performances. In this work, a general method is developed to construct ordered mesoporous TMDs/metal oxides (OM-TMDs/MOs) heterostructures, including WS<sub>2</sub>/WO<sub>3</sub>, WSe<sub>2</sub>/WO<sub>3</sub>, WTe<sub>2</sub>/WO<sub>3</sub>, MoS<sub>2</sub>/MoO<sub>3</sub>, and V<sub>3</sub>S<sub>4</sub>/V<sub>2</sub>O<sub>3</sub>, through one-step thermal sulfurization (selenidation/tellurization) of self-assembled amphiphilic block copolymer/polyoxometalates clusters nanocomposites with ordered mesostructures. The OM-TMDs/MOs possess highly OM structures with high specific surface area, large pore size, and rich active edge sites in the frameworks of heterostructures. The chemiresistive gas sensor based on OM-WS<sub>2</sub>/WO<sub>3</sub> shows excellent NO<sub>2</sub>-sensing performances at room temperature, with high sensitivity, ultrahigh selectivity (<span data-altimg=\"/cms/asset/a3e5cd6e-ac04-41a3-b6e2-cce80c9d4d74/sstr202400376-math-0001.png\"></span><mjx-container ctxtmenu_counter=\"3\" ctxtmenu_oldtabindex=\"1\" jax=\"CHTML\" role=\"application\" sre-explorer- style=\"font-size: 103%; position: relative;\" tabindex=\"0\"><mjx-math aria-hidden=\"true\" location=\"graphic/sstr202400376-math-0001.png\"><mjx-semantics><mjx-mrow><mjx-msub data-semantic-children=\"0,3\" data-semantic- data-semantic-role=\"latinletter\" data-semantic-speech=\"upper S Subscript NO Sub Subscript 2\" data-semantic-type=\"subscript\"><mjx-mi data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"italic\" data-semantic- data-semantic-parent=\"4\" data-semantic-role=\"latinletter\" data-semantic-type=\"identifier\"><mjx-c></mjx-c></mjx-mi><mjx-script style=\"vertical-align: -0.15em; margin-left: -0.032em;\"><mjx-mrow size=\"s\"><mjx-msub data-semantic-children=\"1,2\" data-semantic- data-semantic-parent=\"4\" data-semantic-role=\"unknown\" data-semantic-type=\"subscript\"><mjx-mrow><mjx-mtext data-semantic-annotation=\"clearspeak:unit\" data-semantic-font=\"normal\" data-semantic- data-semantic-parent=\"3\" data-semantic-role=\"unknown\" data-semantic-type=\"text\"><mjx-c></mjx-c><mjx-c></mjx-c></mjx-mtext></mjx-mrow><mjx-script style=\"vertical-align: -0.15em;\"><mjx-mn data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"normal\" data-semantic- data-semantic-parent=\"3\" data-semantic-role=\"integer\" data-semantic-type=\"number\" size=\"s\"><mjx-c></mjx-c></mjx-mn></mjx-script></mjx-msub></mjx-mrow></mjx-script></mjx-msub></mjx-mrow></mjx-semantics></mjx-math><mjx-assistive-mml display=\"inline\" unselectable=\"on\"><math altimg=\"urn:x-wiley:26884062:media:sstr202400376:sstr202400376-math-0001\" display=\"inline\" location=\"graphic/sstr202400376-math-0001.png\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><semantics><","PeriodicalId":21841,"journal":{"name":"Small Structures","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218409","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}
The long genomic DNA molecules in eukaryotes are fragile and prone to entanglement, and must be tightly folded to fit into the micrometric dimensions of mitotic chromosomes. Histones transform the monotonous linear structure of double-helical DNA into a chromatin filament formed by many nucleosomes. A physically consistent model for the packaging of the chromatin filament must be compatible with all the constraints imposed by the structural properties of chromosomes. It has to be compatible with 1) the high concentration of DNA and the elongated cylindrical shape of chromosomes and 2) the known self-associative properties of chromatin, and also with 3) an effective protection of chromosomal DNA from topological entanglement and mechanical breakage. The multilayer chromosome model, in which a repetitive weak interaction between nucleosomes at the nanoscale produces the stacking of many chromatin layers, is compatible with all these constraints. The self-organization of the multilayer structure of the whole chromosome is consistent with current knowledge of the self-assembly of micrometric structures from different repetitive building blocks. The multilayer model justifies the geometry of chromosome bands and translocations, and is compatible with feasible physical mechanisms for the control of gene expression, and for DNA replication, repair, and segregation to daughter cells.
真核生物中的长基因组 DNA 分子非常脆弱，容易缠结，必须紧密折叠才能适应有丝分裂染色体的微米尺寸。组蛋白将双螺旋 DNA 的单线结构转化为由许多核小体形成的染色质丝。染色质丝的物理包装模型必须符合染色体结构特性所带来的所有限制。它必须符合：1）DNA 的高浓度和染色体拉长的圆柱形；2）染色质已知的自结合特性；3）有效保护染色体 DNA 免受拓扑纠缠和机械断裂。在多层染色体模型中，核小体之间在纳米尺度上的重复微弱相互作用产生了许多染色质层的堆积，这与所有这些限制条件都是一致的。整个染色体的多层结构的自组织与目前由不同重复构件自组装微观结构的知识是一致的。多层模型证明了染色体带和易位的几何形状是合理的，并与控制基因表达、DNA 复制、修复和分离到子细胞的可行物理机制相兼容。
{"title":"Rethinking Models of DNA Organization in Micrometer-Sized Chromosomes from the Perspective of the Nanoproperties of Chromatin Favoring a Multilayer Structure","authors":"Joan-Ramon Daban","doi":"10.1002/sstr.202400203","DOIUrl":"https://doi.org/10.1002/sstr.202400203","url":null,"abstract":"The long genomic DNA molecules in eukaryotes are fragile and prone to entanglement, and must be tightly folded to fit into the micrometric dimensions of mitotic chromosomes. Histones transform the monotonous linear structure of double-helical DNA into a chromatin filament formed by many nucleosomes. A physically consistent model for the packaging of the chromatin filament must be compatible with all the constraints imposed by the structural properties of chromosomes. It has to be compatible with 1) the high concentration of DNA and the elongated cylindrical shape of chromosomes and 2) the known self-associative properties of chromatin, and also with 3) an effective protection of chromosomal DNA from topological entanglement and mechanical breakage. The multilayer chromosome model, in which a repetitive weak interaction between nucleosomes at the nanoscale produces the stacking of many chromatin layers, is compatible with all these constraints. The self-organization of the multilayer structure of the whole chromosome is consistent with current knowledge of the self-assembly of micrometric structures from different repetitive building blocks. The multilayer model justifies the geometry of chromosome bands and translocations, and is compatible with feasible physical mechanisms for the control of gene expression, and for DNA replication, repair, and segregation to daughter cells.","PeriodicalId":21841,"journal":{"name":"Small Structures","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218331","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}
Yunchan Lee, Min-Gi Jo, Seongwoo Jeon, Chorong Kim, Jaekyoung Kim, Sanghyuk Wooh, Kee-Youn Yoo, Hyunsik Yoon
Wicking in porous media, such as the spreading of ink on paper or the absorption of moisture by fabric, occurs when water interacts with hydrophilic porous materials through capillary action and evaporation. The directional nature of the wicking phenomenon can be leveraged for various advanced applications, including enhanced heat transfer, colorimetric devices, energy harvesting, and microfluidics. Herein, crack generation is used to induce the anisotropic wicking of water on isolated mesoporous strips. The strips are fabricated by transforming isotropic cracks into anisotropic ones in micropyramid arrays using the Poisson effect in elastomeric blocks. Stretching an elastomeric block increases the period of a pyramid array along one direction while decreasing it in the perpendicular direction because of elastomer shrinkage. This amplifies the difference in the notch angles of pyramidal edges between parallel and perpendicular directions relative to the stretching axis. Consequently, the disparity in notch angles leads to preferential crack generation owing to elevated stress localization on the sharpened notches. Directional wicking is demonstrated using anisotropic strips of mesoporous TiO2 colloidal films and highly anisotropic wicking of ink is illustrated by coating hydrophobic films on mesoporous strips. The anisotropic wicking observed in cracked mesoporous strips can serve as 1D microfluidic channels.
{"title":"Directionally Cracked Mesoporous Colloidal Films by Manipulating Notch Angles and Their Anisotropic Wicking Behavior","authors":"Yunchan Lee, Min-Gi Jo, Seongwoo Jeon, Chorong Kim, Jaekyoung Kim, Sanghyuk Wooh, Kee-Youn Yoo, Hyunsik Yoon","doi":"10.1002/sstr.202400159","DOIUrl":"https://doi.org/10.1002/sstr.202400159","url":null,"abstract":"Wicking in porous media, such as the spreading of ink on paper or the absorption of moisture by fabric, occurs when water interacts with hydrophilic porous materials through capillary action and evaporation. The directional nature of the wicking phenomenon can be leveraged for various advanced applications, including enhanced heat transfer, colorimetric devices, energy harvesting, and microfluidics. Herein, crack generation is used to induce the anisotropic wicking of water on isolated mesoporous strips. The strips are fabricated by transforming isotropic cracks into anisotropic ones in micropyramid arrays using the <i>Poisson</i> effect in elastomeric blocks. Stretching an elastomeric block increases the period of a pyramid array along one direction while decreasing it in the perpendicular direction because of elastomer shrinkage. This amplifies the difference in the notch angles of pyramidal edges between parallel and perpendicular directions relative to the stretching axis. Consequently, the disparity in notch angles leads to preferential crack generation owing to elevated stress localization on the sharpened notches. Directional wicking is demonstrated using anisotropic strips of mesoporous TiO<sub>2</sub> colloidal films and highly anisotropic wicking of ink is illustrated by coating hydrophobic films on mesoporous strips. The anisotropic wicking observed in cracked mesoporous strips can serve as 1D microfluidic channels.","PeriodicalId":21841,"journal":{"name":"Small Structures","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218361","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}
Alan Braschinsky, Toby J. Blundell, Jonathan W. Steed
Nucleation plays an important role in crystallization outcomes, but it is still poorly understood because it occurs on short timescales and small size scales. Consequently, nucleation mechanisms are still challenging to comprehend and predict. Gaining a better understanding, and potentially control, over nucleation pathways, can significantly aid toward more consistent and targeted crystallization outcomes. To achieve this, facile methods that allow for an accurate depiction and analysis of nucleus-sized clusters are needed. Herein, the use of crystalline metal–organic frameworks (MOFs) is reported to entrap clusters of small organic molecules, allowing for an accurate representation of the size and shape of the confined clusters via single-crystal X-Ray diffraction analysis. This is realized by synthesizing high-quality single crystals of lanthanum-based MOFs, which provides well-defined pore spaces for the encapsulation of guest molecules. The results show that the size and shape of the guest molecular clusters within MOFs significantly differ from their bulk equivalents, suggesting that this method can also be used toward discovering novel polymorphs. Additionally, the findings indicate that these small molecular clusters form via intermolecular interactions that do not always dominate the bulk packing, shedding new light on the initial molecular aggregation mechanisms of precritical nuclei.
成核在结晶结果中发挥着重要作用，但由于其发生的时间尺度短、尺寸尺度小，人们对它的了解还很不够。因此，成核机制的理解和预测仍然具有挑战性。更好地了解并控制成核途径，可大大有助于实现更一致、更有针对性的结晶结果。要实现这一目标，需要能够准确描绘和分析晶核大小晶簇的简便方法。本文报告了利用结晶金属有机框架（MOFs）来捕获小分子有机物簇，从而通过单晶 X 射线衍射分析来准确呈现受限簇的大小和形状。这是通过合成高质量的镧基 MOFs 单晶实现的，这种单晶为客体分子的封装提供了定义明确的孔隙。研究结果表明，MOFs 中客体分子团簇的大小和形状与块状分子团簇明显不同，这表明这种方法也可用于发现新型多晶体。此外，研究结果表明，这些小分子团簇是通过分子间相互作用形成的，而这种相互作用并不总是在团状填料中占主导地位，从而为预临界核的初始分子聚集机制提供了新的思路。
{"title":"Netting Crystal Nuclei in Metal–Organic Framework Cavities","authors":"Alan Braschinsky, Toby J. Blundell, Jonathan W. Steed","doi":"10.1002/sstr.202400300","DOIUrl":"https://doi.org/10.1002/sstr.202400300","url":null,"abstract":"Nucleation plays an important role in crystallization outcomes, but it is still poorly understood because it occurs on short timescales and small size scales. Consequently, nucleation mechanisms are still challenging to comprehend and predict. Gaining a better understanding, and potentially control, over nucleation pathways, can significantly aid toward more consistent and targeted crystallization outcomes. To achieve this, facile methods that allow for an accurate depiction and analysis of nucleus-sized clusters are needed. Herein, the use of crystalline metal–organic frameworks (MOFs) is reported to entrap clusters of small organic molecules, allowing for an accurate representation of the size and shape of the confined clusters via single-crystal X-Ray diffraction analysis. This is realized by synthesizing high-quality single crystals of lanthanum-based MOFs, which provides well-defined pore spaces for the encapsulation of guest molecules. The results show that the size and shape of the guest molecular clusters within MOFs significantly differ from their bulk equivalents, suggesting that this method can also be used toward discovering novel polymorphs. Additionally, the findings indicate that these small molecular clusters form via intermolecular interactions that do not always dominate the bulk packing, shedding new light on the initial molecular aggregation mechanisms of precritical nuclei.","PeriodicalId":21841,"journal":{"name":"Small Structures","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218364","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}
Nursaya Zhumabay, Jeremy A. Bau, Rafia Ahmad, Laurentiu Braic, Huabin Zhang, Luigi Cavallo, Magnus Rueping
Photocatalytic water splitting is the most idealistic route to green hydrogen production, but the extensive material requirements for this reaction make it difficult to realize good photocatalysts. Noble metal cocatalysts are often added to photocatalysts to aid in charge separation and improve surface kinetics for H2 evolution. Herein, the high activity of the promising photocatalyst Al-doped SrTiO3 is demonstrated to be ultimately dependent on the cocatalyst used as much as the presence of Al dopant. By tracking the band energetics of photocatalyst electrodes using operando electrochemical attenuated total reflectance surface-enhanced infrared absorption spectroscopy, cocatalysts (especially Rh) are found to shift the quasi-Fermi levels and metal-semiconductor flat-band potentials of photocatalysts in an anodic direction. Furthermore, the size of the shift directly correlates with overall water splitting activity, demonstrating that SrTiO3 becomes more active as photogenerated electrons are stabilized further from the conduction band. Rh on Al-doped SrTiO3 provides the most advantageous band tailoring as confirmed by density functional theory and is experimentally found to provide this effect by eliminating Ti3+-related surface traps in the presence of Al dopants. Therefore, the effect of cocatalysts on water splitting activity is more complicated than previously thought.
{"title":"Tracking Water Splitting Activity by Cocatalyst Identity in SrTiO3","authors":"Nursaya Zhumabay, Jeremy A. Bau, Rafia Ahmad, Laurentiu Braic, Huabin Zhang, Luigi Cavallo, Magnus Rueping","doi":"10.1002/sstr.202400283","DOIUrl":"https://doi.org/10.1002/sstr.202400283","url":null,"abstract":"Photocatalytic water splitting is the most idealistic route to green hydrogen production, but the extensive material requirements for this reaction make it difficult to realize good photocatalysts. Noble metal cocatalysts are often added to photocatalysts to aid in charge separation and improve surface kinetics for H<sub>2</sub> evolution. Herein, the high activity of the promising photocatalyst Al-doped SrTiO<sub>3</sub> is demonstrated to be ultimately dependent on the cocatalyst used as much as the presence of Al dopant. By tracking the band energetics of photocatalyst electrodes using operando electrochemical attenuated total reflectance surface-enhanced infrared absorption spectroscopy, cocatalysts (especially Rh) are found to shift the quasi-Fermi levels and metal-semiconductor flat-band potentials of photocatalysts in an anodic direction. Furthermore, the size of the shift directly correlates with overall water splitting activity, demonstrating that SrTiO<sub>3</sub> becomes more active as photogenerated electrons are stabilized further from the conduction band. Rh on Al-doped SrTiO<sub>3</sub> provides the most advantageous band tailoring as confirmed by density functional theory and is experimentally found to provide this effect by eliminating Ti<sup>3+</sup>-related surface traps in the presence of Al dopants. Therefore, the effect of cocatalysts on water splitting activity is more complicated than previously thought.","PeriodicalId":21841,"journal":{"name":"Small Structures","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218407","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}
Faraghally A. Faraghally, Ahmed Fouad Musa, Ching-Chin Chen, Yu-Hsuan Chen, Yan-Da Chen, Chen-Yu Yeh, Tzu-Chien Wei
The development of photosensitizers with extended π-conjugation and spectral matching to sunlight and fluorescent light is crucial for achieving high power conversion efficiency (PCE) in dye-sensitized solar cells (DSSCs). This study presents a series of novel anthracene-based photosensitizers, AMO1–AMO4. This series has been designed with bulky modified Hagfeldt donors to suppress undesired molecular aggregation, double anthracene groups for enhanced π-conjugation, acetylene groups for improved molecular planarity, and four distinct acceptors to fine-tune their photophysical and electrochemical properties. The performance of the novel dyes in DSSCs is investigated using two copper redox shuttles, CuI/II(dmp)2 and CuI/II(dmodmbp)2. Among the investigated dyes, AMO2 mediated with CuI/II(dmodmbp)2 exhibits the highest power conversion efficiency (PCE) of 10.05% (JSC = 13.72 mA cm 2, VOC = 1.035 V, and FF = 0.71) under sunlight illumination and an outstanding PCE of 34.64% under T5 illumination (6000 lux). These achievements underscore the remarkable potential of anthracene-bridged sensitized DSSCs in indoor and outdoor applications.
{"title":"Double Anthracene-Based Sensitizers for High-Efficiency Dye-Sensitized Solar Cells under Both Sunlight and Indoor Light","authors":"Faraghally A. Faraghally, Ahmed Fouad Musa, Ching-Chin Chen, Yu-Hsuan Chen, Yan-Da Chen, Chen-Yu Yeh, Tzu-Chien Wei","doi":"10.1002/sstr.202400236","DOIUrl":"https://doi.org/10.1002/sstr.202400236","url":null,"abstract":"The development of photosensitizers with extended <i>π</i>-conjugation and spectral matching to sunlight and fluorescent light is crucial for achieving high power conversion efficiency (PCE) in dye-sensitized solar cells (DSSCs). This study presents a series of novel anthracene-based photosensitizers, <b>AMO1–AMO4</b>. This series has been designed with bulky modified Hagfeldt donors to suppress undesired molecular aggregation, double anthracene groups for enhanced π-conjugation, acetylene groups for improved molecular planarity, and four distinct acceptors to fine-tune their photophysical and electrochemical properties. The performance of the novel dyes in DSSCs is investigated using two copper redox shuttles, Cu<sup>I/II</sup>(dmp)<sub>2</sub> and Cu<sup>I/II</sup>(dmodmbp)<sub>2</sub>. Among the investigated dyes, <b>AMO2</b> mediated with Cu<sup>I/II</sup>(dmodmbp)<sub>2</sub> exhibits the highest power conversion efficiency (PCE) of 10.05% (<i>J</i><sub>SC</sub> = 13.72 mA cm <sup>2</sup>, <i>V</i><sub>OC</sub> = 1.035 V, and FF = 0.71) under sunlight illumination and an outstanding PCE of 34.64% under T5 illumination (6000 lux). These achievements underscore the remarkable potential of anthracene-bridged sensitized DSSCs in indoor and outdoor applications.","PeriodicalId":21841,"journal":{"name":"Small Structures","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218363","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}
BiOI is a promising photoelectrocatalyst for oxidation reactions. However, the limited photoelectrocatalytic (PEC) activity necessitates the development of new strategies to modify its surface chemistry and thus enhance functional properties. Herein, we present a simple method to increase photocurrent in a BiOI-based photoanode by exfoliating microspheres of the oxyhalide produced through hydrothermal synthesis. Following exfoliation in isopropanol, the resulting layered BiOI-based colloid contains a greater variety of species, including Bi2O2CO3, I3−, IO3−, Bi5+, and hydroxides, compared to the original BiOI. These additional species do not directly enhance the PEC oxygen evolution reaction (OER) performance. Instead, they are consumed or converted during PEC OER, resulting in more active sites on the photoelectrode and reduced resistance, which ultimately improves the water oxidation performance of the exfoliated BiOI. Over long-term chronoamperometry, the exfoliated BiOI demonstrates a photocurrent twice as high as that of the BiOI microspheres. Analysis of the species after PEC OER reveals that the combination of IO3−, Bi5+, and I3− species on the BiOI is beneficial for charge transfer, thus enhancing the intrinsic PEC properties of the BiOI. This study offers new insights into the role of surface chemistry in determining PEC performance, aiding the optimization of 2D materials-based photoelectrocatalysts.
{"title":"Tuning Surface Chemistry in 2D Layered BiOI by Facile Liquid-Phase Exfoliation for Enhanced Photoelectrocatalytic Oxygen Evolution","authors":"Mengjiao Wang, Jaime Gallego, Micaela Pozzati, Teresa Gatti","doi":"10.1002/sstr.202400275","DOIUrl":"https://doi.org/10.1002/sstr.202400275","url":null,"abstract":"BiOI is a promising photoelectrocatalyst for oxidation reactions. However, the limited photoelectrocatalytic (PEC) activity necessitates the development of new strategies to modify its surface chemistry and thus enhance functional properties. Herein, we present a simple method to increase photocurrent in a BiOI-based photoanode by exfoliating microspheres of the oxyhalide produced through hydrothermal synthesis. Following exfoliation in isopropanol, the resulting layered BiOI-based colloid contains a greater variety of species, including Bi<sub>2</sub>O<sub>2</sub>CO<sub>3</sub>, I<sub>3</sub><sup>−</sup>, IO<sub>3</sub><sup>−</sup>, Bi<sup>5+</sup>, and hydroxides, compared to the original BiOI. These additional species do not directly enhance the PEC oxygen evolution reaction (OER) performance. Instead, they are consumed or converted during PEC OER, resulting in more active sites on the photoelectrode and reduced resistance, which ultimately improves the water oxidation performance of the exfoliated BiOI. Over long-term chronoamperometry, the exfoliated BiOI demonstrates a photocurrent twice as high as that of the BiOI microspheres. Analysis of the species after PEC OER reveals that the combination of IO<sub>3</sub><sup>−</sup>, Bi<sup>5+</sup>, and I<sub>3</sub><sup>−</sup> species on the BiOI is beneficial for charge transfer, thus enhancing the intrinsic PEC properties of the BiOI. This study offers new insights into the role of surface chemistry in determining PEC performance, aiding the optimization of 2D materials-based photoelectrocatalysts.","PeriodicalId":21841,"journal":{"name":"Small Structures","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218411","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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