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":"16 1","pages":""},"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":"18 1","pages":""},"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":"39 1","pages":""},"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":"13 1","pages":""},"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}
Van Du Nguyen, Jieun Park, Seoyeon Choi, Kim Tien Nguyen, Hyungwoo Kim, Jong-Oh Park, Eunpyo Choi
Adoptive cell therapy using natural killer (NK) cells emerges as the next-generation cancer immunotherapy. Based on the intrinsic capability of direct cancer cell necrosis without prior education, a chemotherapeutic, free-drug delivery, NK-cell-based platform can be developed. However, weak targeting of NK cells to solid tumors is observed. In addition, to boost the tumor-killing efficiency, another immune-regulating function should be added to the cells. Herein, a NK-cell-based hybrid system (NK-Robot) conjugated with magnetic nanoparticles (MNPs) that provides 1) efficient guidance of NK cells and 2) targeted delivery of MNPs in situ is demonstrated, taking advantage of a newly designed, stimuli-responsive polymeric linker. Thus, NK cells are allowed to target tumors under magnetic control conditions, and the liberated MNPs effectively reeducate the tumor-associated macrophages (M2) to antitumor macrophages (M1), beneficial for the immunotherapy of tumors. In vivo experiments on BALB/c nude mice further support the finding that NK-Robots effectively inhibit tumor growth.
使用自然杀伤（NK）细胞的适应性细胞疗法已成为下一代癌症免疫疗法。基于 NK 细胞无需事先教育即可直接杀死癌细胞的内在能力，可以开发出一种基于 NK 细胞的化疗、自由给药平台。然而，NK 细胞对实体瘤的靶向性较弱。此外，要想提高杀灭肿瘤的效率，还需要在细胞中加入另一种免疫调节功能。本文展示了一种基于 NK 细胞的混合系统（NK-Robot），该系统与磁性纳米粒子（MNPs）连接，利用新设计的刺激响应型聚合物连接体，可提供：1）NK 细胞的高效引导；2）MNPs 的原位靶向递送。这样，NK 细胞就能在磁控制条件下靶向肿瘤，而释放的 MNPs 能有效地将肿瘤相关巨噬细胞（M2）再教育为抗肿瘤巨噬细胞（M1），从而有利于肿瘤的免疫治疗。在 BALB/c 裸鼠身上进行的体内实验进一步证实了 NK-Robots 能有效抑制肿瘤生长的结论。
{"title":"pH-Sensitive Magnetic Nanoparticle-Mediated Natural-Killer-Cell-Based Microrobots for Dual-Targeted Delivery and Induction of Pro-Inflammatory Macrophage Polarization","authors":"Van Du Nguyen, Jieun Park, Seoyeon Choi, Kim Tien Nguyen, Hyungwoo Kim, Jong-Oh Park, Eunpyo Choi","doi":"10.1002/sstr.202400149","DOIUrl":"https://doi.org/10.1002/sstr.202400149","url":null,"abstract":"Adoptive cell therapy using natural killer (NK) cells emerges as the next-generation cancer immunotherapy. Based on the intrinsic capability of direct cancer cell necrosis without prior education, a chemotherapeutic, free-drug delivery, NK-cell-based platform can be developed. However, weak targeting of NK cells to solid tumors is observed. In addition, to boost the tumor-killing efficiency, another immune-regulating function should be added to the cells. Herein, a NK-cell-based hybrid system (NK-Robot) conjugated with magnetic nanoparticles (MNPs) that provides 1) efficient guidance of NK cells and 2) targeted delivery of MNPs in situ is demonstrated, taking advantage of a newly designed, stimuli-responsive polymeric linker. Thus, NK cells are allowed to target tumors under magnetic control conditions, and the liberated MNPs effectively reeducate the tumor-associated macrophages (M2) to antitumor macrophages (M1), beneficial for the immunotherapy of tumors. In vivo experiments on BALB/c nude mice further support the finding that NK-Robots effectively inhibit tumor growth.","PeriodicalId":21841,"journal":{"name":"Small Structures","volume":"165 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218358","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}
Naresh-Kumar Pendyala, Cedric Gonzales, Antonio Guerrero
Halide perovskite is very attractive for the fabrication of energy-efficient memristors for neuromorphic applications. However, reproducibility, stability, and understanding the switching behavior still lag in comparison to other technologies. Herein, a deep-level understanding of perovskite memristors is obtained by the development of highly reproducible devices. The approach is based on a highly stable perovskite formulation (MAPbBr3) and the use of preoxidized silver (AgI) as a buffer layer. Here, reliable perovskite memristors with device yields approaching 100%, stabilities of >104 cycles for volatile response, and adequate conditions for linear potentiation/depression for nonvolatile response are demonstrated. Using these devices, the nature of the dual volatile and nonvolatile response is understood. It is shown that applying short SET voltage (VSET) pulses leads to ion displacement inside the perovskite material with the formation of an ionic double layer close to the contacts. The displacement of the ions contributes to the series resistance of the device and to a volatile response with ions diffusing back to the perovskite at V < VSET. Alternatively, long VSET pulses lead to a gradual increase in current, the appearance of a chemical inductor, and a nonvolatile response. The observed nonvolatile regime is related to the formation of Ag+ conductive filaments.
卤化物包晶对于制造用于神经形态应用的高能效忆阻器极具吸引力。然而，与其他技术相比，可重复性、稳定性和对开关行为的理解仍然落后。在本文中，通过开发高度可重现的器件，我们对包晶体忆阻器有了深层次的了解。该方法基于一种高度稳定的过氧化物配方（MAPbBr3），并使用预氧化银（AgI）作为缓冲层。在这里，我们展示了可靠的过氧化物忆阻器，其器件产量接近 100%，挥发性响应的稳定性达到 104 个周期，非挥发性响应的线性增效/抑制条件充分。通过使用这些器件，我们了解了易失性和非易失性双响应的性质。研究表明，施加短 SET 电压（VSET）脉冲会导致过氧化物材料内部的离子位移，并在触点附近形成离子双层。离子的位移会增加器件的串联电阻，并导致离子在 V < VSET 时扩散回包晶的波动响应。另一种情况是，长 VSET 脉冲导致电流逐渐增加，出现化学感应和非挥发性响应。观察到的非挥发性机制与 Ag+ 导电丝的形成有关。
{"title":"Decoupling Volatile and Nonvolatile Response in Reliable Halide Perovskite Memristors","authors":"Naresh-Kumar Pendyala, Cedric Gonzales, Antonio Guerrero","doi":"10.1002/sstr.202400380","DOIUrl":"https://doi.org/10.1002/sstr.202400380","url":null,"abstract":"Halide perovskite is very attractive for the fabrication of energy-efficient memristors for neuromorphic applications. However, reproducibility, stability, and understanding the switching behavior still lag in comparison to other technologies. Herein, a deep-level understanding of perovskite memristors is obtained by the development of highly reproducible devices. The approach is based on a highly stable perovskite formulation (MAPbBr<sub>3</sub>) and the use of preoxidized silver (AgI) as a buffer layer. Here, reliable perovskite memristors with device yields approaching 100%, stabilities of >10<sup>4</sup> cycles for volatile response, and adequate conditions for linear potentiation/depression for nonvolatile response are demonstrated. Using these devices, the nature of the dual volatile and nonvolatile response is understood. It is shown that applying short SET voltage (<i>V</i><sub>SET</sub>) pulses leads to ion displacement inside the perovskite material with the formation of an ionic double layer close to the contacts. The displacement of the ions contributes to the series resistance of the device and to a volatile response with ions diffusing back to the perovskite at <i>V</i> < <i>V</i><sub>SET</sub>. Alternatively, long <i>V</i><sub>SET</sub> pulses lead to a gradual increase in current, the appearance of a chemical inductor, and a nonvolatile response. The observed nonvolatile regime is related to the formation of Ag<sup>+</sup> conductive filaments.","PeriodicalId":21841,"journal":{"name":"Small Structures","volume":"110 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218332","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}
Jun-Woo Lee, Jong Ho Won, Woosup Kim, Jwa-Bin Jeon, Myung-Yeon Cho, Sunghoon Kim, Minkyung Kim, Chulhwan Park, Weon Ho Shin, Kanghee Won, Sang-Mo Koo, Jong-Min Oh
With the increasing demand for modern high-voltage electronic devices in electric vehicles and renewable-energy systems, power semiconductor devices with high breakdown fields are becoming essential. β-Gallium oxide (Ga2O3), which has a theoretical breakdown field of 8 MV cm−1, is being studied as a next-generation power-switch material. However, realizing a breakdown field close to this theoretical value remains challenging. In this study, an aerosol deposition-manufactured Ga2O3 film boasting an extremely high breakdown field, achieved through thickness optimization, heat treatment, and a unique nozzle-tilting method, is developed. This study explores the effect of oxygen vacancies on the dielectric constant, breakdown field, and microstructure of Ga2O3 films. Through these methods, Ga2O3 films with a denser (98.88%) and uniform surface, made less affected by oxygen vacancies through nozzle tilting and post-annealing at 800 °C, are produced, resulting in appropriate dielectric constants (9.3 at 10 kHz), low leakage currents (5.8 × 10−11 A cm−2 at 20 kV cm−1), and a very high breakdown field of 5.5 MV cm−1. The results of this study suggest that aerosol-deposited Ga2O3 layers have great potential to enable power switches with reliable switching.
{"title":"Ultrahigh Breakdown Field in Gallium (III) Oxide Dielectric Structure Fabricated by Novel Aerosol Deposition Method","authors":"Jun-Woo Lee, Jong Ho Won, Woosup Kim, Jwa-Bin Jeon, Myung-Yeon Cho, Sunghoon Kim, Minkyung Kim, Chulhwan Park, Weon Ho Shin, Kanghee Won, Sang-Mo Koo, Jong-Min Oh","doi":"10.1002/sstr.202400321","DOIUrl":"https://doi.org/10.1002/sstr.202400321","url":null,"abstract":"With the increasing demand for modern high-voltage electronic devices in electric vehicles and renewable-energy systems, power semiconductor devices with high breakdown fields are becoming essential. β-Gallium oxide (Ga<sub>2</sub>O<sub>3</sub>), which has a theoretical breakdown field of 8 MV cm<sup>−1</sup>, is being studied as a next-generation power-switch material. However, realizing a breakdown field close to this theoretical value remains challenging. In this study, an aerosol deposition-manufactured Ga<sub>2</sub>O<sub>3</sub> film boasting an extremely high breakdown field, achieved through thickness optimization, heat treatment, and a unique nozzle-tilting method, is developed. This study explores the effect of oxygen vacancies on the dielectric constant, breakdown field, and microstructure of Ga<sub>2</sub>O<sub>3</sub> films. Through these methods, Ga<sub>2</sub>O<sub>3</sub> films with a denser (98.88%) and uniform surface, made less affected by oxygen vacancies through nozzle tilting and post-annealing at 800 °C, are produced, resulting in appropriate dielectric constants (9.3 at 10 kHz), low leakage currents (5.8 × 10<sup>−11 </sup>A cm<sup>−2</sup> at 20 kV cm<sup>−1</sup>), and a very high breakdown field of 5.5 MV cm<sup>−1</sup>. The results of this study suggest that aerosol-deposited Ga<sub>2</sub>O<sub>3</sub> layers have great potential to enable power switches with reliable switching.","PeriodicalId":21841,"journal":{"name":"Small Structures","volume":"38 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218334","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}
Qile Li, Shuochen Fan, Xiaodong Luan, Ke Xu, Xianqi Wei, Qinlin Shao, Huaping Peng, Linxing Shi
All-inorganic perovskite CsPbBr3 (CPB) nanocrystals (NCs) are not widely applied in aqueous environments due to their readily decomposable nature. Therefore, the aqueous-phase preparation of CPB NCs has been a considerable challenge. In this work, a feasible method is proposed for preparing aqueous-phase core–shell CPB nanorods (NRs) encapsulated with polydopamine (PDA) by employing a multifunctional additive cesium trifluoroacetate (Cs-TFA). Highly luminescent TFA-CPB NRs are obtained via a chemical transformation of Cs4PbBr6 NCs in water. Subsequently, PDA constitutes a robust shell on the surface of TFA-CPB NRs through the covalent oxidative polymerization, which effectively reduces the original dynamic properties of surface ligands, retards the decomposition of ligands and inhibits the leakage of Pb2+ ions. The results demonstrate that the fluorescence intensity of TFA-CPB@PDA NRs maintains 49.3% of the initial intensity after 136 days. Meanwhile, the NRs exhibit low cytotoxicity, and the cell viability remains at 80% when the concentration of the NRs is 200 μg mL−1. The reliable preparation of aqueous-phase core–shell perovskite NRs (PNRs) will facilitate their development in many fields, such as materials science, biology, medicine, and their applications in aqueous environments.
{"title":"Aqueous-Phase Preparation of Core–Shell Perovskite Nanorods Encapsulated in Polydopamine with Ultrahigh Water Stability","authors":"Qile Li, Shuochen Fan, Xiaodong Luan, Ke Xu, Xianqi Wei, Qinlin Shao, Huaping Peng, Linxing Shi","doi":"10.1002/sstr.202400182","DOIUrl":"https://doi.org/10.1002/sstr.202400182","url":null,"abstract":"All-inorganic perovskite CsPbBr<sub>3</sub> (CPB) nanocrystals (NCs) are not widely applied in aqueous environments due to their readily decomposable nature. Therefore, the aqueous-phase preparation of CPB NCs has been a considerable challenge. In this work, a feasible method is proposed for preparing aqueous-phase core–shell CPB nanorods (NRs) encapsulated with polydopamine (PDA) by employing a multifunctional additive cesium trifluoroacetate (Cs-TFA). Highly luminescent TFA-CPB NRs are obtained via a chemical transformation of Cs<sub>4</sub>PbBr<sub>6</sub> NCs in water. Subsequently, PDA constitutes a robust shell on the surface of TFA-CPB NRs through the covalent oxidative polymerization, which effectively reduces the original dynamic properties of surface ligands, retards the decomposition of ligands and inhibits the leakage of Pb<sup>2+</sup> ions. The results demonstrate that the fluorescence intensity of TFA-CPB@PDA NRs maintains 49.3% of the initial intensity after 136 days. Meanwhile, the NRs exhibit low cytotoxicity, and the cell viability remains at 80% when the concentration of the NRs is 200 μg mL<sup>−1</sup>. The reliable preparation of aqueous-phase core–shell perovskite NRs (PNRs) will facilitate their development in many fields, such as materials science, biology, medicine, and their applications in aqueous environments.","PeriodicalId":21841,"journal":{"name":"Small Structures","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218333","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}
Mingliang He, Jia Qiao, Binghua Zhou, Jie Wang, Shien Guo, Gan Jet Hong Melvin, Mingxi Wang, Hironori Ogata, Yoong Ahm Kim, Masaki Tanemura, Shuwen Wang, Mauricio Terrones, Morinobu Endo, Fei Zhang, Zhipeng Wang
Layered double hydroxide (LDH) is considered a highly promising electrode material for supercapacitors (SCs) due to its high theoretical specific capacitance. However, LDH powders often suffer from poor electrical conductivity, structure pulverization, slow charge transport, and insufficient active sites. Herein, a self-supporting electrode with a Mott–Schottky heterostructure has been designed for high-performance SCs. The electrode consists of low crystallinity NiCo-LDH nanosheets and vertical graphene (VG) directly grown on carbon cloth. The LDH was converted from a metal–organic framework (MOF) by the sol–gel method. This self-supporting electrode provides fast charge transfer, reducing the pulverization effect and energy barrier. The Mott–Schottky heterostructure of LDH@VG regulates electron density and enhances electron transfer, as confirmed by density functional theory calculation. The optimized LDH@VG heterostructure electrode exhibits an excellent areal capacitance of 5513.8 mF cm−2 and rate capability of 82.1%. Furthermore, the fabricated hybrid SC demonstrates excellent energy density of 404.8 μWh cm−2 at 1.6 mW cm−2 and a remarkable cycling life, with a capacitance of 92.0% after 10 000 cycles. This work not only provides a simple dip-coating and MOF conversion method to synthesize heterojunction-based electrodes, but also broadens the horizon for designing advanced electrode materials for SCs.
{"title":"Controllable Metal–Organic Framework-Derived NiCo-Layered Double Hydroxide Nanosheets on Vertical Graphene as Mott–Schottky Heterostructure for High-Performance Hybrid Supercapacitor","authors":"Mingliang He, Jia Qiao, Binghua Zhou, Jie Wang, Shien Guo, Gan Jet Hong Melvin, Mingxi Wang, Hironori Ogata, Yoong Ahm Kim, Masaki Tanemura, Shuwen Wang, Mauricio Terrones, Morinobu Endo, Fei Zhang, Zhipeng Wang","doi":"10.1002/sstr.202400207","DOIUrl":"https://doi.org/10.1002/sstr.202400207","url":null,"abstract":"Layered double hydroxide (LDH) is considered a highly promising electrode material for supercapacitors (SCs) due to its high theoretical specific capacitance. However, LDH powders often suffer from poor electrical conductivity, structure pulverization, slow charge transport, and insufficient active sites. Herein, a self-supporting electrode with a Mott–Schottky heterostructure has been designed for high-performance SCs. The electrode consists of low crystallinity NiCo-LDH nanosheets and vertical graphene (VG) directly grown on carbon cloth. The LDH was converted from a metal–organic framework (MOF) by the sol–gel method. This self-supporting electrode provides fast charge transfer, reducing the pulverization effect and energy barrier. The Mott–Schottky heterostructure of LDH@VG regulates electron density and enhances electron transfer, as confirmed by density functional theory calculation. The optimized LDH@VG heterostructure electrode exhibits an excellent areal capacitance of 5513.8 mF cm<sup>−2</sup> and rate capability of 82.1%. Furthermore, the fabricated hybrid SC demonstrates excellent energy density of 404.8 μWh cm<sup>−2</sup> at 1.6 mW cm<sup>−2</sup> and a remarkable cycling life, with a capacitance of 92.0% after 10 000 cycles. This work not only provides a simple dip-coating and MOF conversion method to synthesize heterojunction-based electrodes, but also broadens the horizon for designing advanced electrode materials for SCs.","PeriodicalId":21841,"journal":{"name":"Small Structures","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218352","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}
Subin Kim, Ki-Yeop Cho, JunHwa Kwon, Kiyeon Sim, KwangSup Eom, Thomas F. Fuller
Lithium-metal anodes (LMAs) are the ultimate choice for realizing high-energy-density batteries; however, its use is hindered by problematic Li growth in the form of dendrites. To alleviate dendritic Li growth, the preparation of LMAs with a lithiophilic current collector (CC) is effective; however, applying a lithiophilic CC to LMAs is still challenging due to the manufacturing complexity involved in the separate lithiophilic treatment and lithiation processes. Herein, a facile one-pot LMA fabrication method by utilizing thiourea (TU) as a precursor is proposed. A lithiophilic Cu2S layer is formed on Cu foam (CF) by the in situ electrochemical oxidation of TU (CuxSCF), and the lithiation of CC is performed via subsequent Li electrodeposition (Li@CuxSCF). The Cu2S on CuxSCF can lead to uniform Li deposition by providing lithiophilic sites, and it is converted to form ionic-conductive Li2S-rich solid electrolyte interphase layer. Resultantly, CuxSCF significantly enhances the cycling performance of LMAs compared to CF. Specifically, a LiFePO4/Li@CuxSCF full-cell lithium-metal battery (LMB) with a low n/p ratio (1.6) exhibits capacity retention of 95.6% at 0.5 C (220 cycles) and can maintain 85.0% of initial capacity (425 cycles, n/p = 4) at 2.0 C. LMBs with LiNi0.6Co0.2Mn0.2 and LiNi0.8Co0.1Mn0.1 also exhibit improved electrochemical performance.
{"title":"In Situ Electrochemical Interfacial Manipulation Enabling Lithiophilic Li Metal Anode with Inorganic-Rich Solid Electrolyte Interphases for Stable Li Metal Batteries","authors":"Subin Kim, Ki-Yeop Cho, JunHwa Kwon, Kiyeon Sim, KwangSup Eom, Thomas F. Fuller","doi":"10.1002/sstr.202400254","DOIUrl":"https://doi.org/10.1002/sstr.202400254","url":null,"abstract":"Lithium-metal anodes (LMAs) are the ultimate choice for realizing high-energy-density batteries; however, its use is hindered by problematic Li growth in the form of dendrites. To alleviate dendritic Li growth, the preparation of LMAs with a lithiophilic current collector (CC) is effective; however, applying a lithiophilic CC to LMAs is still challenging due to the manufacturing complexity involved in the separate lithiophilic treatment and lithiation processes. Herein, a facile one-pot LMA fabrication method by utilizing thiourea (TU) as a precursor is proposed. A lithiophilic Cu<sub>2</sub>S layer is formed on Cu foam (CF) by the in situ electrochemical oxidation of TU (Cu<sub><i>x</i></sub>SCF), and the lithiation of CC is performed via subsequent Li electrodeposition (Li@Cu<sub><i>x</i></sub>SCF). The Cu<sub>2</sub>S on Cu<sub><i>x</i></sub>SCF can lead to uniform Li deposition by providing lithiophilic sites, and it is converted to form ionic-conductive Li<sub>2</sub>S-rich solid electrolyte interphase layer. Resultantly, Cu<sub><i>x</i></sub>SCF significantly enhances the cycling performance of LMAs compared to CF. Specifically, a LiFePO<sub>4</sub>/Li@Cu<sub><i>x</i></sub>SCF full-cell lithium-metal battery (LMB) with a low <i>n</i>/<i>p</i> ratio (1.6) exhibits capacity retention of 95.6% at 0.5 C (220 cycles) and can maintain 85.0% of initial capacity (425 cycles, <i>n</i>/<i>p</i> = 4) at 2.0 C. LMBs with LiNi<sub>0.6</sub>Co<sub>0.2</sub>Mn<sub>0.2</sub> and LiNi<sub>0.8</sub>Co<sub>0.1</sub>Mn<sub>0.1</sub> also exhibit improved electrochemical performance.","PeriodicalId":21841,"journal":{"name":"Small Structures","volume":"165 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142218354","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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