The Journal of Physical Chemistry C最新文献_第9页

Photoluminescence and Scintillation Mechanism of Cs4PbBr6 Cs4PbBr6 的光致发光和闪烁机制

IF 4.126 3区化学 Q2 CHEMISTRY, PHYSICAL

The Journal of Physical Chemistry C

Pub Date : 2024-11-11 DOI: 10.1021/acs.jpcc.4c06347

J. Jasper van Blaaderen, Andries van Hattem, Jence T. Mulder, Daniel Biner, Karl W. Krämer, Pieter Dorenbos

Small bandgap scintillators have gained significant attention in recent years. Especially Cs₄PbBr₆ is an interesting material, mitigating the small Stokes shift-related problem of perovskites like CsPbBr₃. In this work, optical and scintillation properties of Cs₄PbBr₆ single crystals are investigated as a function of temperature, with a detailed focus at 10 K. The Cs₄PbBr₆ single crystals were grown using the vertical Bridgman method. Due to incongruent melting, CsPbBr₃ inclusions are formed, generating a 540 nm emission band. Prepairing Cs₄PbBr₆ via solid-state synthesis yields CsPbBr₃-inclusion-free material, showing no green 540 nm emission band. In Cs₄PbBr₆ samples with and without CsPbBr₃ inclusions, a new emission band at 610 nm ascribed to an unknown defect was found. Based on the presented experiments, an emission mechanism is proposed for Cs₄PbBr₆. This shows that both defects and CsPbBr₃ inclusions play a role in the emission behavior of Cs₄PbBr₆ but only the CsPbBr₃ inclusions are responsible for the 540 nm emission.

近年来，小带隙闪烁体备受关注。Cs4PbBr6 尤其是一种有趣的材料，它缓解了 CsPbBr3 等过氧化物的小斯托克斯偏移相关问题。在这项工作中，研究了 Cs4PbBr6 单晶的光学和闪烁特性与温度的函数关系，重点是 10 K 的温度。由于不协调熔化，形成了 CsPbBr3 包裹体，产生了 540 nm 的发射带。通过固态合成对 Cs4PbBr6 进行预处理可得到不含 CsPbBr3 夹杂的材料，从而不显示绿色 540 纳米发射带。在含有和不含 CsPbBr3 包裹体的 Cs4PbBr6 样品中，发现了一条 610 纳米波长的新发射带，该发射带归因于一种未知缺陷。基于上述实验，提出了 Cs4PbBr6 的发射机制。这表明缺陷和 CsPbBr3 杂质在 Cs4PbBr6 的发射行为中都起了作用，但只有 CsPbBr3 杂质对 540 nm 的发射负责。

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引用次数: 0

SERS Spectra Indicate the Molecular Effects of 7-Nitrobenz-2-oxa-1,3-diazole (NBD) on Living Cells SERS 光谱显示 7-硝基苯并-2-氧杂-1,3-二唑 (NBD) 对活细胞的分子效应

IF 3.3 3区化学 Q2 CHEMISTRY, PHYSICAL

The Journal of Physical Chemistry C

Pub Date : 2024-11-11 DOI: 10.1021/acs.jpcc.4c0526010.1021/acs.jpcc.4c05260

Yiqing Feng, Florian Gärber, Essa M. Saied, Cecilia Spedalieri, Zdravko Kochovski, Stephan Werner, Christoph Pratsch, Christoph Arenz, Stephan Seifert and Janina Kneipp*,

7-Nitrobenz-2-oxa-1,3-diazole (NBD) is a widely used fluorescent label for proteins, peptides, and lipids. Its chloride derivative, NBD-Cl, can be highly reactive toward thiol and amine groups, forming stable fluorescent adducts. When labeling the ubiquitous lipid molecule ceramide, NBD-ceramide (NBDCER) aids in visualizing sphingolipid metabolism in cells. This study investigates intracellular molecular changes induced by NBD-Cl and NBDCER using surface-enhanced Raman scattering (SERS). SERS spectra from the endolysosomal compartment of two cell lines, 3T3 fibroblast cells and J774 macrophage cells, obtained with gold nanoparticles as probes, reveal changes in the molecular composition and interactions under different incubation conditions. Applying the random forest (RF)-based algorithm surrogate minimal depth (SMD) to the SERS data to identify important spectral classifiers and their relations, both NBD-Cl and NBDCER are found to alter the biochemical makeup of the endolysosomal compartment. The data indicate significant structural and interaction changes in the molecular constituents of the cells that are in agreement with possible interference of the labels in the cellular metabolism and the reaction of NBD-Cl with functional groups of cellular molecules.

7-硝基苯并-2-氧杂-1,3-二唑（NBD）是一种广泛应用于蛋白质、肽和脂类的荧光标记。它的氯化物衍生物 NBD-Cl 对硫醇和胺基团具有高活性，能形成稳定的荧光加合物。在标记无处不在的脂质分子神经酰胺时，NBD-神经酰胺（NBDCER）有助于观察细胞内的鞘脂代谢。本研究利用表面增强拉曼散射（SERS）技术研究了 NBD-Cl 和 NBDCER 诱导的细胞内分子变化。以金纳米粒子为探针，从 3T3 成纤维细胞和 J774 巨噬细胞这两种细胞系的内溶酶体区获得的 SERS 光谱显示了不同培养条件下分子组成和相互作用的变化。将基于随机森林（RF）的算法代理最小深度（SMD）应用于 SERS 数据以识别重要的光谱分类器及其关系，发现 NBD-Cl 和 NBDCER 都会改变内溶酶体区室的生化组成。数据表明，细胞分子成分的结构和相互作用发生了重大变化，这与标签可能干扰细胞代谢以及 NBD-Cl 与细胞分子的功能基团发生反应是一致的。

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引用次数: 0

Ammonia Iron: An Epistemic Challenge with Practical Consequences 氨铁：具有实际后果的认识论挑战

IF 3.3 3区化学 Q2 CHEMISTRY, PHYSICAL

The Journal of Physical Chemistry C

Pub Date : 2024-11-11 DOI: 10.1021/acs.jpcc.4c0516110.1021/acs.jpcc.4c05161

Robert Schlögl*,

Ammonia synthesis from elements using the Haber–Bosch (HB) process will grow in demand above the present world-scale application through the need to transport renewable energy. The actual broad academic research effort concentrates on novel solutions, as the existing technology is considered to be mature. The paper investigates this statement by analyzing the relevance of the foundational model for optimizing the iron HB catalyst. The epistemic analysis dwells upon reductionistic assumptions, opening science gaps between model catalysts and performance operation. The mechanistic understanding of the HB process limits expectations for future development but opens up aspects of the optimization potential. It lies in the material chemistry of how the structure of the active sites, which is fixed in space and time in the model concept, is realized in performance catalysts. Significant chances are seen to further improve the existing reliable technology through optimization of the iron-based material. Its intricate property profile precludes success by further empirical searches but requires the full power of a knowledge-based approach guided by a suggested development of the functional model.

利用哈伯-博施（HB）工艺从元素中合成氨的需求将因运输可再生能源的需要而增长，超过目前的世界应用规模。由于现有技术被认为已经成熟，实际的广泛学术研究工作集中在新型解决方案上。本文通过分析优化 HB 铁催化剂的基础模型的相关性来研究这一说法。认识论分析以还原论假设为基础，揭示了模型催化剂与性能操作之间的科学差距。对碳氢化合物工艺的机械理解限制了对未来发展的期望，但也开启了优化潜力的各个方面。在模型概念中，活性位点的结构在空间和时间上都是固定的，而在高性能催化剂中，活性位点的结构是如何实现的，这取决于材料化学。通过优化铁基材料，进一步改进现有可靠技术的机会很大。铁基材料的特性错综复杂，无法通过进一步的经验搜索获得成功，而需要在功能模型开发建议的指导下，充分发挥知识方法的力量。

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引用次数: 0

Dependence of Oxygen Diffusion on the La and Sr Configuration in Melilite-Type La1+xSr1–xGa3O7+x/2 by Neural Network Potential Molecular Dynamics Simulation 通过神经网络势能分子动力学模拟研究 Melilite-Type La1+xSr1-xGa3O7+x/2 中氧扩散对 La 和 Sr 配置的依赖性

IF 4.126 3区化学 Q2 CHEMISTRY, PHYSICAL

The Journal of Physical Chemistry C

Pub Date : 2024-11-11 DOI: 10.1021/acs.jpcc.4c03617

Tsubasa Koyama, Masanobu Nakayama, Judith Schuett, Steffen Neitzel-Grieshammer

Oxide ion conductors, including O₂ sensors and solid electrolytes for solid oxide fuel cells, are used in various applications. O^2– vacancies are often the charge carriers in oxide ion conductors, including fluorite- and perovskite-type oxides. Recently, melilite-type La_1+xSr_1–xGa₃O_7+x/2 (0 ≤ x ≤ 1) materials have attracted attention because of their high O^2– ion conductivity resulting from the migration of interstitial oxide ions formed for charge compensation. In this study, we evaluate the ionic conductivities of various cation configurations by molecular dynamics calculations using a universal neural network potential and investigate the relationship between conductivity and the cation configuration. The activation energy of ionic conduction is significantly dependent on the cation (La, Sr) configuration, even for the same composition. The disordered La/Sr arrangement tends to have a higher ionic conductivity than the energetically stable La/Sr arrangement. Such an effect is prominent in the medium-temperature range (800–1100 K).

氧化物离子导体，包括氧气传感器和固体氧化物燃料电池的固体电解质，被广泛应用于各种领域。O2- 空位通常是氧化物离子导体（包括萤石型和透辉石型氧化物）中的电荷载流子。最近，熔融型 La1+xSr1-xGa3O7+x/2 （0 ≤ x ≤ 1）材料因其电荷补偿形成的间隙氧化物离子迁移而产生的高 O2- 离子导电性引起了人们的关注。在本研究中，我们利用通用神经网络势通过分子动力学计算评估了各种阳离子构型的离子传导性，并研究了传导性与阳离子构型之间的关系。离子传导的活化能明显取决于阳离子（La、Sr）的构型，即使是相同的成分。无序的 La/Sr 排列往往比能量稳定的 La/Sr 排列具有更高的离子传导性。这种效应在中温范围（800-1100 K）内表现突出。

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引用次数: 0

Insights into Catalytic Oxidative Reaction Mechanisms of Pentane on the Ru(0001) Surface 对 Ru(0001) 表面戊烷催化氧化反应机理的见解

IF 4.126 3区化学 Q2 CHEMISTRY, PHYSICAL

The Journal of Physical Chemistry C

Pub Date : 2024-11-11 DOI: 10.1021/acs.jpcc.4c05735

Mazharul M. Islam, C. Richard A. Catlow, Alberto Roldan

Developing efficient and selective oxidative transformations of light alkanes into alkenes or oxygenates is vital for advancing to cleaner and more efficient chemical processes. A suitable selective catalyst is required to ease reaction conditions and ensure the formation of desired oxygenated compounds. Here, using periodic density functional theory, we have investigated the suitability of a ruthenium catalyst for the partial oxidation of n-pentane using molecular oxygen. The first step of the process involves the dehydrogenation of primary or secondary carbons in the aliphatic chain, resulting in an adsorbed hydride structure on the metal surface. The intermediate may proceed through different reaction pathways, leading to various products. The successive dehydrogenation, a faster process than the first oxidative dehydrogenation, produces pentene and a water molecule. Alternatively, the direct interaction of the hydroxyl group with the pentyl hydride produces alcohol. The atomistic simulations reveal that Ru is a suitable candidate for catalyzing the conversion of alkanes into alkenes and oxygenates. As a significant outcome, we have observed that catalytic oxidative dehydrogenation is more feasible than direct catalytic dehydrogenation for yielding olefins from alkanes.

开发轻烷向烯烃或含氧化合物的高效和选择性氧化转化技术，对于推进更清洁、更高效的化学工艺至关重要。需要一种合适的选择性催化剂来简化反应条件，并确保形成所需的含氧化合物。在此，我们利用周期密度泛函理论研究了一种钌催化剂是否适用于利用分子氧对正戊烷进行部分氧化。该过程的第一步涉及脂肪族链中一级或二级碳的脱氢，从而在金属表面形成吸附氢化物结构。该中间体可通过不同的反应途径生成各种产物。连续脱氢过程比第一次氧化脱氢过程更快，可生成戊烯和一个水分子。或者，羟基与戊基氢化物的直接作用产生酒精。原子模拟显示，Ru 是催化烷烃转化为烯和含氧化合物的合适候选物质。作为一项重要成果，我们观察到催化氧化脱氢比直接催化脱氢更能从烷烃中生成烯烃。

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引用次数: 0

Elucidation of a Metastable p(2 × 1) O Atom Adlayer Structure on Cu(111) 阐明铜（111）上可迁移的 p(2 × 1) O 原子层结构

IF 4.126 3区化学 Q2 CHEMISTRY, PHYSICAL

The Journal of Physical Chemistry C

Pub Date : 2024-11-11 DOI: 10.1021/acs.jpcc.4c04452

Audrey Dannar, Gunnar Louis Sly, Vinita Lal, Eva Peurrung, Volkan Cinar, Nisa Ulumuddin, Hojoon Lim, Adrian Hunt, Jean-Sabin McEwen, Iradwikanari Waluyo, E. Charles H. Sykes

Cu-based catalysts are ubiquitous in many industrial reactions, including methanol synthesis. Under partially oxidizing conditions, Cu catalysts can have dynamic surface structures that greatly influence their reactivities. Therefore, elucidating the surface structures that are present on Cu, and looking for metastable structures, aids in the long term goal of understanding and controlling their catalytic behavior. Thin-film copper oxides such as the “29” and “44” structures have been described at length in the literature, but precursors to these thin-film oxides can be challenging to study because they exist only under certain conditions. Using a combination of experimental and computational surface science techniques, we discovered, modeled, and quantified a previously unreported O atom adlayer structure on Cu(111) with a p(2 × 1) unit cell. We used scanning tunneling microscopy to visualize the striped 2 × 1 structure and density functional theory (DFT) structure optimizations to identify the thermodynamically most favorable positions of Cu and O atoms in a p(2 × 1) unit cell. Using X-ray photoelectron spectroscopy and temperature-programmed desorption, we determined the stoichiometry of the structure to be 2:1 for surface Cu atoms to O adatoms, the same stoichiometry as that modeled by DFT. This work reports a new metastable structure formed on Cu(111) at the very initial stages of oxidation and is therefore worth considering in models of catalytically relevant redox processes at Cu surfaces.

铜基催化剂在包括甲醇合成在内的许多工业反应中无处不在。在部分氧化条件下，铜催化剂可能具有动态表面结构，从而极大地影响其反应活性。因此，阐明铜的表面结构并寻找可转移的结构，有助于实现了解和控制其催化行为的长期目标。薄膜铜氧化物（如 "29 "和 "44 "结构）在文献中已有详细描述，但这些薄膜氧化物的前体只有在特定条件下才会存在，因此研究起来具有挑战性。我们结合使用了实验和计算表面科学技术，在具有 p(2 × 1) 单元的铜(111)上发现了以前未曾报道过的 O 原子叠层结构，并对其进行了建模和量化。我们使用扫描隧道显微镜来观察条纹状 2 × 1 结构，并通过密度泛函理论 (DFT) 结构优化来确定铜原子和 O 原子在 p(2 × 1) 单胞中热力学上最有利的位置。利用 X 射线光电子能谱和温度编程解吸法，我们确定了该结构中表面铜原子与 O 原子的配位比为 2:1，与 DFT 模拟的配位比相同。这项研究报告了一种在 Cu(111) 氧化的最初阶段形成的新的可转移结构，因此值得在 Cu 表面催化相关氧化还原过程的模型中加以考虑。

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引用次数: 0

Ammonia Iron: An Epistemic Challenge with Practical Consequences 氨铁：具有实际后果的认识论挑战

IF 4.126 3区化学 Q2 CHEMISTRY, PHYSICAL

The Journal of Physical Chemistry C

Pub Date : 2024-11-11 DOI: 10.1021/acs.jpcc.4c05161

Robert Schlögl

Ammonia synthesis from elements using the Haber–Bosch (HB) process will grow in demand above the present world-scale application through the need to transport renewable energy. The actual broad academic research effort concentrates on novel solutions, as the existing technology is considered to be mature. The paper investigates this statement by analyzing the relevance of the foundational model for optimizing the iron HB catalyst. The epistemic analysis dwells upon reductionistic assumptions, opening science gaps between model catalysts and performance operation. The mechanistic understanding of the HB process limits expectations for future development but opens up aspects of the optimization potential. It lies in the material chemistry of how the structure of the active sites, which is fixed in space and time in the model concept, is realized in performance catalysts. Significant chances are seen to further improve the existing reliable technology through optimization of the iron-based material. Its intricate property profile precludes success by further empirical searches but requires the full power of a knowledge-based approach guided by a suggested development of the functional model.

利用哈伯-博施（HB）工艺从元素中合成氨的需求将因运输可再生能源的需要而增长，超过目前的世界应用规模。由于现有技术被认为已经成熟，实际的广泛学术研究工作集中在新型解决方案上。本文通过分析优化 HB 铁催化剂的基础模型的相关性来研究这一说法。认识论分析以还原论假设为基础，揭示了模型催化剂与性能操作之间的科学差距。对碳氢化合物工艺的机械理解限制了对未来发展的期望，但也开启了优化潜力的各个方面。在模型概念中，活性位点的结构在空间和时间上都是固定的，而在高性能催化剂中，活性位点的结构是如何实现的，这取决于材料化学。通过优化铁基材料，进一步改进现有可靠技术的机会很大。铁基材料的特性错综复杂，无法通过进一步的经验搜索获得成功，而需要在功能模型开发建议的指导下，充分发挥知识方法的力量。

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引用次数: 0

SERS Spectra Indicate the Molecular Effects of 7-Nitrobenz-2-oxa-1,3-diazole (NBD) on Living Cells SERS 光谱显示 7-硝基苯并-2-氧杂-1,3-二唑 (NBD) 对活细胞的分子效应

IF 4.126 3区化学 Q2 CHEMISTRY, PHYSICAL

The Journal of Physical Chemistry C

Pub Date : 2024-11-11 DOI: 10.1021/acs.jpcc.4c05260

Yiqing Feng, Florian Gärber, Essa M. Saied, Cecilia Spedalieri, Zdravko Kochovski, Stephan Werner, Christoph Pratsch, Christoph Arenz, Stephan Seifert, Janina Kneipp

7-Nitrobenz-2-oxa-1,3-diazole (NBD) is a widely used fluorescent label for proteins, peptides, and lipids. Its chloride derivative, NBD-Cl, can be highly reactive toward thiol and amine groups, forming stable fluorescent adducts. When labeling the ubiquitous lipid molecule ceramide, NBD-ceramide (NBDCER) aids in visualizing sphingolipid metabolism in cells. This study investigates intracellular molecular changes induced by NBD-Cl and NBDCER using surface-enhanced Raman scattering (SERS). SERS spectra from the endolysosomal compartment of two cell lines, 3T3 fibroblast cells and J774 macrophage cells, obtained with gold nanoparticles as probes, reveal changes in the molecular composition and interactions under different incubation conditions. Applying the random forest (RF)-based algorithm surrogate minimal depth (SMD) to the SERS data to identify important spectral classifiers and their relations, both NBD-Cl and NBDCER are found to alter the biochemical makeup of the endolysosomal compartment. The data indicate significant structural and interaction changes in the molecular constituents of the cells that are in agreement with possible interference of the labels in the cellular metabolism and the reaction of NBD-Cl with functional groups of cellular molecules.

7-Nitrobenz-2-oxa-1,3-diazole (NBD) 是一种广泛应用于蛋白质、肽和脂质的荧光标记。它的氯化物衍生物 NBD-Cl 对硫醇和胺基团具有高活性，能形成稳定的荧光加合物。在标记无处不在的脂质分子神经酰胺时，NBD-神经酰胺（NBDCER）有助于观察细胞内的鞘脂代谢。本研究利用表面增强拉曼散射（SERS）技术研究了 NBD-Cl 和 NBDCER 诱导的细胞内分子变化。以金纳米粒子为探针，从 3T3 成纤维细胞和 J774 巨噬细胞这两种细胞系的内溶酶体区获得的 SERS 光谱显示了不同培养条件下分子组成和相互作用的变化。将基于随机森林（RF）的算法代理最小深度（SMD）应用于 SERS 数据以识别重要的光谱分类器及其关系，发现 NBD-Cl 和 NBDCER 都会改变内溶酶体区室的生化组成。数据表明，细胞分子成分的结构和相互作用发生了重大变化，这与标签可能干扰细胞代谢以及 NBD-Cl 与细胞分子的功能基团发生反应是一致的。

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引用次数: 0

Mechanisms of TADF/Phosphorescence-Sensitized Fluorescence in OLED Emissive Layers and Their Impacts on Device Performances: A Theoretical Insight OLED 发射层中的 TADF/磷光敏化荧光机制及其对设备性能的影响：理论见解

IF 4.126 3区化学 Q2 CHEMISTRY, PHYSICAL

The Journal of Physical Chemistry C

Pub Date : 2024-11-11 DOI: 10.1021/acs.jpcc.4c03496

Yue Xie, Jiaqi Li, Le Mei, Shulin Luo, Tao Zhang, Xiao-Hong Zhang, Xian-Kai Chen

Organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence or phosphorescence-sensitized fluorescence [TADF-sensitized fluorescence (TSF) or phosphorescence-sensitized fluorescence (PSF)] open the door for devices with high efficiency, better color purity, long lifetime, and low-efficiency roll-off. However, the photophysical processes and their impact on device performances in TSF and PSF systems are not clearly understood to date. In this work, the photophysical processes for the TSF and the PSF systems are in depth investigated by combining molecular dynamics simulation and quantum-chemistry calculations. In the studied TSF [PCTF/TBRb] system and the PSF [Ir(ppy)₂acac/TBRb] system, the film morphologies, electronic properties, and kinetic processes are analyzed in detail. The calculated results indicate that the [PCTF/TBRb] system and the [Ir(ppy)₂acac/TBRb] system exhibit obvious TSF and PSF features, respectively. The difference between the two sensitization systems is the utilization process of the T₁ excitons of the sensitizers. The rates of reverse intersystem crossing (k_RISC^TADF) and the triplet-singlet Förster resonance energy transfer (k_T-SFRET^Ph-G) are the decisive factors in the internal quantum efficiency (IQE) of the TSF and the PSF systems, respectively. Moreover, it can be found that the effect of k_RISC^TADF on the IQE in the TSF system is stronger than the effect of k_T-SFRET^Ph-G on the IQE in the PSF system. We hope that these results will promote an in-depth understanding of the mechanisms of the TSF and the PSF systems and their impacts on device performances, accelerating the development of highly efficient sensitized OLEDs.

基于热激活延迟荧光或磷光敏化荧光[TADF-sensitized fluorescence (TSF) or phosphorescence-sensitized fluorescence (PSF)]的有机发光二极管（OLED）为具有高效率、更高色纯度、长寿命和低效率衰减的设备打开了大门。然而，迄今为止，人们对 TSF 和 PSF 系统中的光物理过程及其对器件性能的影响还不甚了解。本文结合分子动力学模拟和量子化学计算，深入研究了 TSF 和 PSF 系统的光物理过程。在所研究的 TSF [PCTF/TBRb] 体系和 PSF [Ir(ppy)2acac/TBRb] 体系中，详细分析了薄膜形态、电子特性和动力学过程。计算结果表明，[PCTF/TBRb]体系和[Ir(ppy)2acac/TBRb]体系分别表现出明显的TSF和PSF特征。两种敏化体系的区别在于敏化剂 T1 激子的利用过程。反向系统间交叉率（kRISCTADF）和三重子-小三重子佛尔斯特共振能量传递率（kT-SFRETPh-G）分别是影响 TSF 和 PSF 系统内部量子效率（IQE）的决定性因素。此外，我们还发现 kRISCTADF 对 TSF 系统 IQE 的影响要强于 kT-SFRETPh-G 对 PSF 系统 IQE 的影响。我们希望这些结果能促进人们深入了解 TSF 和 PSF 系统的机理及其对器件性能的影响，从而加速高效敏化有机发光二极管的开发。

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引用次数: 0

Unveiling the Impact of Substitutional Doping on the Oxidation Behavior of MoAlB: A Comprehensive First-Principles Study 揭示取代掺杂对 MoAlB 氧化行为的影响：全面的第一性原理研究

IF 4.126 3区化学 Q2 CHEMISTRY, PHYSICAL

The Journal of Physical Chemistry C

Pub Date : 2024-11-11 DOI: 10.1021/acs.jpcc.4c04317

Bashini Kankanamge, Deniz Çakır

This study utilized density functional theory to examine how Si, Zr, Cr, and C doping affects the oxidation behavior of the (010) and (111) surfaces of MoAlB. Si doping at the Al site weakens Al–O bonds, while Zr doping at the Mo site significantly strengthens the Zr–O bonds, enhancing the stability of the doped structure. Zr and C doping cause notable variations in Al, B, and Mo defect formation energies on the surface layer, while Si has a lesser impact. Zr doping reduces Al vacancy diffusion barriers by 0.2 eV, promoting Al migration toward the surface and enhancing the formation of a protective Al₂O₃ layer on the MoAlB surface. In contrast, Si doping increases the Al vacancy diffusion barrier energy by 0.1 eV, potentially slowing oxidation on the surface. Zr increases oxygen penetration barriers into subsurface layers, strengthening surface oxidation but limiting deeper migration, while Si lowers these barriers, allowing more extensive oxygen diffusion. Our molecular dynamics simulations at 1200 K showed that Zr attracts more oxygen atoms on the surface but prevents deep penetration of O atoms. These findings underscore the distinct effects of different dopants on the oxidation mechanics and stability of MoAlB, with implications for high-temperature applications.

本研究利用密度泛函理论研究了 Si、Zr、Cr 和 C 掺杂如何影响 MoAlB (010) 和 (111) 表面的氧化行为。在 Al 位点掺入 Si 会减弱 Al-O 键，而在 Mo 位点掺入 Zr 会显著增强 Zr-O 键，从而提高掺杂结构的稳定性。掺杂 Zr 和 C 会导致表层的 Al、B 和 Mo 缺陷形成能发生显著变化，而掺杂 Si 则影响较小。Zr 掺杂使铝空位扩散阻抗降低了 0.2 eV，促进了铝向表面迁移，并增强了 MoAlB 表面 Al2O3 保护层的形成。相比之下，掺入硅会使铝空位扩散势垒能增加 0.1 eV，从而可能减缓表面氧化。Zr 增加了氧气进入次表层的穿透势垒，加强了表面氧化，但限制了向深层的迁移，而 Si 则降低了这些势垒，允许更广泛的氧气扩散。我们在 1200 K 下进行的分子动力学模拟显示，Zr 在表面吸引了更多的氧原子，但却阻止了 O 原子的深层渗透。这些发现强调了不同掺杂剂对 MoAlB 氧化力学和稳定性的不同影响，对高温应用具有重要意义。

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引用次数: 0