Pub Date : 2025-01-15DOI: 10.1021/acs.jpclett.4c03464
Arun Jangir, Duc Tam Ho, Udo Schwingenschlögl
Materials exhibiting both metallic and semiconducting states, including two-dimensional transition metal dichalcogenides (TMDs), have numerous applications. We therefore investigate the effects of axial and shear strains on the phase energetics of pristine and striped TMDs using density functional theory and classical molecular dynamics simulations. We demonstrate that control of the phase distribution can be achieved by the integration of strain engineering and Kirigami techniques. Our results extend the understanding of the phase energetics in TMDs and reveal an effective strategy for creating virtually defect-free metal-semiconductor-metal junctions.
{"title":"Control of the Phase Distribution in TMDs by Strain Engineering and Kirigami Techniques","authors":"Arun Jangir, Duc Tam Ho, Udo Schwingenschlögl","doi":"10.1021/acs.jpclett.4c03464","DOIUrl":"https://doi.org/10.1021/acs.jpclett.4c03464","url":null,"abstract":"Materials exhibiting both metallic and semiconducting states, including two-dimensional transition metal dichalcogenides (TMDs), have numerous applications. We therefore investigate the effects of axial and shear strains on the phase energetics of pristine and striped TMDs using density functional theory and classical molecular dynamics simulations. We demonstrate that control of the phase distribution can be achieved by the integration of strain engineering and Kirigami techniques. Our results extend the understanding of the phase energetics in TMDs and reveal an effective strategy for creating virtually defect-free metal-semiconductor-metal junctions.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"15 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142981708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-15DOI: 10.1021/acs.jpclett.4c03211
Zeping Ou, Yu Jie Zheng, Chen Li, Kuan Sun
Hybrid organic–inorganic halide perovskites (HOIPs) have garnered a significant amount of attention due to their exceptional photoelectric conversion efficiency. However, they still face considerable challenges in large-scale applications, primarily due to their instability. One key factor influencing this instability is the lattice softness attributed to the A-site cations. In this study, we investigated the effects of four different A-site cations (MA, FA, EA, and GA) on the lattice softness of perovskites by using a combination of ab initio molecular dynamics and first-principles calculations. Our results demonstrate that an increase in the number of hydrogen bonds for A-site cations correlates with enhanced lattice and atomic fluctuations, resulting in a reduction in the bulk modulus and an increase in the lattice softness. The strength of hydrogen bonding of the A-site cation increases the rotational energy barrier of the cation, along with the formation energy and kinetic coupling between the A-site cation and the [PbI6]4– octahedron. Consequently, this increases the lifetime of hydrogen bonding and enhances the rigidity of the perovskite lattice. Notably, we found that EA cations, which exhibit stronger hydrogen bonding with fewer total hydrogen bonds, can limit the rotation of the A-site cation, inhibit the rocking motion of the [PbI6]4– octahedron, and thereby increase the rigidity of the inherently soft perovskite lattice, ultimately enhancing the stability of the material. Our findings elucidate the effect of hydrogen bonding in A-site cations on the lattice softness of perovskites, providing valuable theoretical insights for the design of more stable HOIPs.
有机-无机混合卤化物过氧化物（HOIPs）因其卓越的光电转换效率而备受关注。然而，它们在大规模应用中仍然面临着相当大的挑战，这主要是由于它们的不稳定性。影响这种不稳定性的一个关键因素是 A 位阳离子的晶格软性。在本研究中，我们结合 ab initio 分子动力学和第一性原理计算，研究了四种不同的 A 位阳离子（MA、FA、EA 和 GA）对包晶石晶格软度的影响。我们的研究结果表明，A 位阳离子氢键数量的增加与晶格和原子波动的增强相关，从而导致体模量的降低和晶格软度的增加。A 位阳离子氢键的强度增加了阳离子的旋转能垒，同时也增加了 A 位阳离子与 [PbI6]4- 八面体之间的形成能和动力学耦合。因此，这增加了氢键的寿命，提高了包晶晶格的刚性。值得注意的是，我们发现 EA 阳离子以较少的氢键总量表现出较强的氢键作用，可以限制 A 位阳离子的旋转，抑制 [PbI6]4- 八面体的摇摆运动，从而增加固有软性包晶晶格的刚性，最终提高材料的稳定性。我们的研究结果阐明了 A 位阳离子中的氢键对包晶石晶格软度的影响，为设计更稳定的 HOIPs 提供了宝贵的理论依据。
{"title":"Role of A-Site Cation Hydrogen Bonds in Hybrid Organic–Inorganic Perovskites: A Theoretical Insight","authors":"Zeping Ou, Yu Jie Zheng, Chen Li, Kuan Sun","doi":"10.1021/acs.jpclett.4c03211","DOIUrl":"https://doi.org/10.1021/acs.jpclett.4c03211","url":null,"abstract":"Hybrid organic–inorganic halide perovskites (HOIPs) have garnered a significant amount of attention due to their exceptional photoelectric conversion efficiency. However, they still face considerable challenges in large-scale applications, primarily due to their instability. One key factor influencing this instability is the lattice softness attributed to the A-site cations. In this study, we investigated the effects of four different A-site cations (MA, FA, EA, and GA) on the lattice softness of perovskites by using a combination of ab initio molecular dynamics and first-principles calculations. Our results demonstrate that an increase in the number of hydrogen bonds for A-site cations correlates with enhanced lattice and atomic fluctuations, resulting in a reduction in the bulk modulus and an increase in the lattice softness. The strength of hydrogen bonding of the A-site cation increases the rotational energy barrier of the cation, along with the formation energy and kinetic coupling between the A-site cation and the [PbI<sub>6</sub>]<sup>4–</sup> octahedron. Consequently, this increases the lifetime of hydrogen bonding and enhances the rigidity of the perovskite lattice. Notably, we found that EA cations, which exhibit stronger hydrogen bonding with fewer total hydrogen bonds, can limit the rotation of the A-site cation, inhibit the rocking motion of the [PbI<sub>6</sub>]<sup>4–</sup> octahedron, and thereby increase the rigidity of the inherently soft perovskite lattice, ultimately enhancing the stability of the material. Our findings elucidate the effect of hydrogen bonding in A-site cations on the lattice softness of perovskites, providing valuable theoretical insights for the design of more stable HOIPs.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"74 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142981711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We fabricated Co-based catalysts by the low-temperature thermal decomposition of R–Co intermetallics (R = Y, La, or Ce) to reduce the temperature of ammonia cracking for hydrogen production. The catalysts synthesized are nanocomposites of Co/ROx with a metal-rich composition. In the Co13/LaO1.5 catalyst derived from LaCo13, Co nanoparticles of 10–30 nm size are enclosed by the LaO1.5 matrix. The nanocomposite exhibited superior catalytic activity (91% at 500 °C), which was attributed to dual advantages; the low workfunction of the supporter, O-deficient LaO1.5-x nanoparticles, promotes electron donation to the Co catalyst in the interface, which leads to enhanced N–H bond dissociation. Moreover, such a composite structure is effective in suppressing the grain growth of Co nanoparticles because the LaO1.5 layer works as a diffusion barrier against Co. The thermal decomposition of intermetallics is a new route for the facile synthesis of catalysts having an electronically active support.
{"title":"Ammonia Decomposition Catalyzed by Co Nanoparticles Encapsulated in Rare Earth Oxide","authors":"Hiroshi Mizoguchi, Shunqin Luo, Masato Sasase, Masaaki Kitano, Hideo Hosono","doi":"10.1021/acs.jpclett.4c03309","DOIUrl":"https://doi.org/10.1021/acs.jpclett.4c03309","url":null,"abstract":"We fabricated Co-based catalysts by the low-temperature thermal decomposition of R–Co intermetallics (R = Y, La, or Ce) to reduce the temperature of ammonia cracking for hydrogen production. The catalysts synthesized are nanocomposites of Co/RO<sub><i>x</i></sub> with a metal-rich composition. In the Co<sub>13</sub>/LaO<sub>1.5</sub> catalyst derived from LaCo<sub>13</sub>, Co nanoparticles of 10–30 nm size are enclosed by the LaO<sub>1.5</sub> matrix. The nanocomposite exhibited superior catalytic activity (91% at 500 °C), which was attributed to dual advantages; the low workfunction of the supporter, O-deficient LaO<sub>1.5-x</sub> nanoparticles, promotes electron donation to the Co catalyst in the interface, which leads to enhanced N–H bond dissociation. Moreover, such a composite structure is effective in suppressing the grain growth of Co nanoparticles because the LaO<sub>1.5</sub> layer works as a diffusion barrier against Co. The thermal decomposition of intermetallics is a new route for the facile synthesis of catalysts having an electronically active support.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"29 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142975571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-13DOI: 10.1021/acs.jpclett.4c03203
Mengjia Li, Cong Chen
A significant barrier to the commercialization of solution-processed perovskite solar cells (PSCs) is the chemical instability of the components in precursor solutions under ambient conditions. This instability leads to solution aging, which subsequently diminishes the quality and reproducibility of the resulting PSCs. Inspired by recent published works, which focused on the deprotonation of organic cations, the oxidation of iodide, and the formation of undesired byproducts, we here systematically summarize and provide an outlook on the research directions and perspectives of the origin of precursor solution aging and countermeasures, such as using stabilizing additives, redox shuttles, Schiff base reactions, and green solvents. We are aiming to provide insight into potential paths for achieving reproducible and efficient PSCs with high operational stability.
{"title":"The Aging Chemistry of Perovskite Precursor Solutions","authors":"Mengjia Li, Cong Chen","doi":"10.1021/acs.jpclett.4c03203","DOIUrl":"https://doi.org/10.1021/acs.jpclett.4c03203","url":null,"abstract":"A significant barrier to the commercialization of solution-processed perovskite solar cells (PSCs) is the chemical instability of the components in precursor solutions under ambient conditions. This instability leads to solution aging, which subsequently diminishes the quality and reproducibility of the resulting PSCs. Inspired by recent published works, which focused on the deprotonation of organic cations, the oxidation of iodide, and the formation of undesired byproducts, we here systematically summarize and provide an outlook on the research directions and perspectives of the origin of precursor solution aging and countermeasures, such as using stabilizing additives, redox shuttles, Schiff base reactions, and green solvents. We are aiming to provide insight into potential paths for achieving reproducible and efficient PSCs with high operational stability.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"29 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142968421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Due to the global demands on carbon neutralization, CO2 separation membranes, particularly those based on two-dimensional (2D) materials, have attracted increasing attention. However, recent works have focused on the chemical decoration of membranes to realize the selective transport, leading to the compromised stability in the presence of moisture. Herein, we develop a series of 2D capillaries based on layered double hydroxide (LDH), graphene oxide, and vermiculite to enhance the oversaturation of CO2 in the confined water for promoting the membrane permselectivity. By employing the dielectric spectroscopy as a probe to unveil oversaturation, the dissolved CO2 can be enhanced by up to ten times facilitated by water confined in the 2D capillary, particularly constructed by the LDH, endowing the uprise of CO2/N2 separation factor by 43 times. Therefore, our work opens an avenue to the future design of selective membranes by modulating the confined water beyond chemical modification.
{"title":"Enhancing CO2 Oversaturation in the Confined Water Enables Superior Gas Selectivity of 2D Membranes","authors":"Xin-Hai Yan, Weijun He, Shouwei Liao, Xu Liang, Yongan Yang, Libo Li, Kai-Ge Zhou, Zhongyi Jiang","doi":"10.1021/acs.jpclett.4c03228","DOIUrl":"https://doi.org/10.1021/acs.jpclett.4c03228","url":null,"abstract":"Due to the global demands on carbon neutralization, CO<sub>2</sub> separation membranes, particularly those based on two-dimensional (2D) materials, have attracted increasing attention. However, recent works have focused on the chemical decoration of membranes to realize the selective transport, leading to the compromised stability in the presence of moisture. Herein, we develop a series of 2D capillaries based on layered double hydroxide (LDH), graphene oxide, and vermiculite to enhance the oversaturation of CO<sub>2</sub> in the confined water for promoting the membrane permselectivity. By employing the dielectric spectroscopy as a probe to unveil oversaturation, the dissolved CO<sub>2</sub> can be enhanced by up to ten times facilitated by water confined in the 2D capillary, particularly constructed by the LDH, endowing the uprise of CO<sub>2</sub>/N<sub>2</sub> separation factor by 43 times. Therefore, our work opens an avenue to the future design of selective membranes by modulating the confined water beyond chemical modification.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"45 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142968424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chlorophyll (Chl) is the most abundant light-harvesting pigment of oxygenic photosynthetic organisms; however, the Q-band energetics and relaxation dynamics remain unclear. In this work, we have applied femtosecond time-resolved (fs-TA) absorption spectroscopy in 430–1,700 nm to Chls a and b in diluted pyridine solutions under selective optical excitation within their Q-bands. The results revealed distinct near-infrared absorption features of the Bx,y ← Qy and Bx,y ← Qx transitions in 930–1,700 nm, which together with the steady-state absorption in 400–700 nm unveiled the Qx(0,0)-state energy that lies 1,000 ± 400 and 600 ± 400 cm–1 above the Qy(0,0)-state for Chls a and b, respectively. In addition, the Qx-to-Qy internal conversion time constants are estimated to be less than 80 fs for Chls a and b. These findings may shed light on understanding the roles of the Chls in the primary excitation energy transfer reactions of photosynthesis.
叶绿素（Chl）是含氧光合生物最丰富的光收集色素；然而，其 Q 波段的能量学和弛豫动力学仍不清楚。在这项工作中，我们对稀释的吡啶溶液中的叶绿素 a 和叶绿素 b 在其 Q 波段内的选择性光激发下进行了 430-1,700 纳米波长的飞秒时间分辨吸收光谱分析。结果发现，在 930-1,700 纳米波长范围内，Bx,y ← Qy 和 Bx,y ← Qx 转变具有明显的近红外吸收特征，这些特征与 400-700 纳米波长范围内的稳态吸收共同揭示了 Chls a 和 b 的 Qx(0,0)-state 能量，它们分别比 Qy(0,0)-state 高出 1,000 ± 400 和 600 ± 400 cm-1。此外，Chls a 和 b 的 Qx 到 Qy 内部转换时间常数估计小于 80 fs。这些发现可能有助于了解 Chls 在光合作用的初级激发能量转移反应中的作用。
{"title":"The Q-Band Energetics and Relaxation of Chlorophylls a and b as Revealed by Visible-to-Near Infrared Time-Resolved Absorption Spectroscopy","authors":"Rong-Yao Gao, Jian-Wei Zou, Yan-Ping Shi, Dan-Hong Li, Junrong Zheng, Jian-Ping Zhang","doi":"10.1021/acs.jpclett.4c03171","DOIUrl":"https://doi.org/10.1021/acs.jpclett.4c03171","url":null,"abstract":"Chlorophyll (Chl) is the most abundant light-harvesting pigment of oxygenic photosynthetic organisms; however, the Q-band energetics and relaxation dynamics remain unclear. In this work, we have applied femtosecond time-resolved (<i>fs</i>-TA) absorption spectroscopy in 430–1,700 nm to Chls <i>a</i> and <i>b</i> in diluted pyridine solutions under selective optical excitation within their Q-bands. The results revealed distinct near-infrared absorption features of the B<sub>x,y</sub> ← Q<sub><i>y</i></sub> and B<sub>x,y</sub> ← Q<sub><i>x</i></sub> transitions in 930–1,700 nm, which together with the steady-state absorption in 400–700 nm unveiled the Q<sub>x(0,0)</sub>-state energy that lies 1,000 ± 400 and 600 ± 400 cm<sup>–1</sup> above the Q<sub>y(0,0)</sub>-state for Chls <i>a</i> and <i>b</i>, respectively. In addition, the Q<sub><i>x</i></sub>-to-Q<sub><i>y</i></sub> internal conversion time constants are estimated to be less than 80 fs for Chls <i>a</i> and <i>b</i>. These findings may shed light on understanding the roles of the Chls in the primary excitation energy transfer reactions of photosynthesis.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"29 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142975572","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-13DOI: 10.1021/acs.jpclett.4c03302
Khansa Younus, Yu Zhou, Menglong Zhu, Defeng Xu, Xiao Guo, Asad Ahmed, Fangping Ouyang, Han Huang, Si Xiao, Zhihui Chen, Jun He
The two colors (parallel vs perpendicular) were labeled incorrectly in Figure 3a,b. The correction of Figure 3. Figure 3. Polarization-dependent SHG measurements for 3-layer (a), 5-layer (b), 15.1 nm (c), 30.5 nm (d), and 35.2 nm (e) thick NbSe2 flakes in parallel (blue dots) and perpendicular (red dots) modes. Light blue and red areas stand for their respective fitting results. The green arrows indicate the AC direction of the sample. (f) The determined SHG anisotropies for both parallel (black balls and line) and perpendicular (orange balls and line) modes. This article has not yet been cited by other publications.
{"title":"Correction to “Observation of Anisotropic Second Harmonic Generation in Two-Dimensional Niobium Diselenide”","authors":"Khansa Younus, Yu Zhou, Menglong Zhu, Defeng Xu, Xiao Guo, Asad Ahmed, Fangping Ouyang, Han Huang, Si Xiao, Zhihui Chen, Jun He","doi":"10.1021/acs.jpclett.4c03302","DOIUrl":"https://doi.org/10.1021/acs.jpclett.4c03302","url":null,"abstract":"The two colors (parallel vs perpendicular) were labeled incorrectly in Figure 3a,b. The correction of Figure 3. Figure 3. Polarization-dependent SHG measurements for 3-layer (a), 5-layer (b), 15.1 nm (c), 30.5 nm (d), and 35.2 nm (e) thick NbSe<sub>2</sub> flakes in parallel (blue dots) and perpendicular (red dots) modes. Light blue and red areas stand for their respective fitting results. The green arrows indicate the AC direction of the sample. (f) The determined SHG anisotropies for both parallel (black balls and line) and perpendicular (orange balls and line) modes. This article has not yet been cited by other publications.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"12 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142975578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-13DOI: 10.1021/acs.jpclett.4c03279
Yiqi Huo, Shuo Li, Luo Yan, Ningbo Li, Jing Zou, Junjie He, Tong Zhou, Thomas Frauenheim, Sergei Tretiak, Liujiang Zhou
Ultrashort laser pulses are extensively used for efficient manipulation of interfacial spin injection in two-dimensional van der Waals (vdW) heterostructures. However, physical processes accompanying the photoinduced spin transfer dynamics on the all-semiconductor ferromagnetic vdW heterostructure remain largely unexplored. Here, we present a computational investigation of the femtosecond laser pulse induced purely electron-mediated spin transfer dynamics at a time scale of less than 50 fs in a vdW heterostructure. The latter is composed of two semiconducting monolayers, namely, a ferromagnetic material CrSBr and a nonmagnetic phosphorene, and is denoted as CrSBr-P. We observe an ultrafast spin injection from the Cr atoms to the P atoms in a few femtoseconds by both optically induced and interfacial atom-mediated spin transfer effects. We also show that the demagnetization and spin transfer in the ferromagnetic–nonmagnetic CrSBr-P vdW heterostructure can be sensitively manipulated by laser pulses with different fluences. Our study offers a microscopic understanding of spin dynamics in these vdW heterostructures aiming toward their potential spintronic applications, which rely on optically controlled spin transfer processes.
{"title":"Ultrafast Laser-Induced Spin Dynamics in All-Semiconductor Ferromagnetic CrSBr–Phosphorene Heterostructures","authors":"Yiqi Huo, Shuo Li, Luo Yan, Ningbo Li, Jing Zou, Junjie He, Tong Zhou, Thomas Frauenheim, Sergei Tretiak, Liujiang Zhou","doi":"10.1021/acs.jpclett.4c03279","DOIUrl":"https://doi.org/10.1021/acs.jpclett.4c03279","url":null,"abstract":"Ultrashort laser pulses are extensively used for efficient manipulation of interfacial spin injection in two-dimensional van der Waals (vdW) heterostructures. However, physical processes accompanying the photoinduced spin transfer dynamics on the all-semiconductor ferromagnetic vdW heterostructure remain largely unexplored. Here, we present a computational investigation of the femtosecond laser pulse induced purely electron-mediated spin transfer dynamics at a time scale of less than 50 fs in a vdW heterostructure. The latter is composed of two semiconducting monolayers, namely, a ferromagnetic material CrSBr and a nonmagnetic phosphorene, and is denoted as CrSBr-P. We observe an ultrafast spin injection from the Cr atoms to the P atoms in a few femtoseconds by both optically induced and interfacial atom-mediated spin transfer effects. We also show that the demagnetization and spin transfer in the ferromagnetic–nonmagnetic CrSBr-P vdW heterostructure can be sensitively manipulated by laser pulses with different fluences. Our study offers a microscopic understanding of spin dynamics in these vdW heterostructures aiming toward their potential spintronic applications, which rely on optically controlled spin transfer processes.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"16 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142968468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-13DOI: 10.1021/acs.jpclett.4c03477
Harikrishna Sahu, Mingzhe Li, Madhubanti Mukherjee, Liang Yue, H. Jerry Qi, Rampi Ramprasad
Photochemistry-based silica formation offers a pathway toward energy-efficient and controlled fabrication processes. While the transformation of poly(dimethylsiloxane) (PDMS) to silica (often referred to as SiOx due to incomplete conversion) under deep ultraviolet (DUV) irradiation in the presence of oxygen/ozone has experimentally been validated, the detailed mechanism remains elusive. This study demonstrates the underlying molecular-level mechanism of PDMS-to-silica conversion using density functional theory (DFT) calculations. Our findings reveal that atomic oxygen plays a key role in converting PDMS to silica by catalyzing the replacement of -CH3 groups to -OH groups, with a barrier-less insertion into Si–C and C–H bonds, eventually leading to condensation reactions that produce silica and formaldehyde and/or formic acid as byproducts. The proposed molecular pathway has further been validated through controlled experiments, which confirm the successive -CH3 to -OH replacements and identify gaseous byproducts such as formaldehyde. These findings offer insights into the fundamental processes involved in photochemistry-based silica fabrication and could pave the way for advancements in energy-efficient materials synthesis.
{"title":"Elucidating Photochemical Conversion Mechanism of PDMS to Silica under Deep UV Light and Ozone","authors":"Harikrishna Sahu, Mingzhe Li, Madhubanti Mukherjee, Liang Yue, H. Jerry Qi, Rampi Ramprasad","doi":"10.1021/acs.jpclett.4c03477","DOIUrl":"https://doi.org/10.1021/acs.jpclett.4c03477","url":null,"abstract":"Photochemistry-based silica formation offers a pathway toward energy-efficient and controlled fabrication processes. While the transformation of poly(dimethylsiloxane) (PDMS) to silica (often referred to as SiO<sub><i>x</i></sub> due to incomplete conversion) under deep ultraviolet (DUV) irradiation in the presence of oxygen/ozone has experimentally been validated, the detailed mechanism remains elusive. This study demonstrates the underlying molecular-level mechanism of PDMS-to-silica conversion using density functional theory (DFT) calculations. Our findings reveal that atomic oxygen plays a key role in converting PDMS to silica by catalyzing the replacement of -CH<sub>3</sub> groups to -OH groups, with a barrier-less insertion into Si–C and C–H bonds, eventually leading to condensation reactions that produce silica and formaldehyde and/or formic acid as byproducts. The proposed molecular pathway has further been validated through controlled experiments, which confirm the successive -CH<sub>3</sub> to -OH replacements and identify gaseous byproducts such as formaldehyde. These findings offer insights into the fundamental processes involved in photochemistry-based silica fabrication and could pave the way for advancements in energy-efficient materials synthesis.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"27 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142968460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-13DOI: 10.1021/acs.jpclett.4c02949
Kirill Zinovjev, Carles Curutchet
Incorporation of environment and vibronic effects in simulations of optical spectra and excited state dynamics is commonly done by combining molecular dynamics with excited state calculations, which allows to estimate the spectral density describing the frequency-dependent system-bath coupling strength. The need for efficient sampling, however, usually leads to the adoption of classical force fields despite well-known inaccuracies due to the mismatch with the excited state method. Here, we present a multiscale strategy that overcomes this limitation by combining EMLE simulations based on electrostatically embedded ML potentials with the QM/MMPol polarizable embedding model to compute the excited states and spectral density of 3-methyl-indole, the chromophoric moiety of tryptophan that mediates a variety of important biological functions, in the gas phase, in water solution, and in the human serum albumin protein. Our protocol provides highly accurate results that faithfully reproduce their ab initio QM/MM counterparts, thus paving the way for accurate investigations on the interrelation between the time scales of biological motion and the photophysics of tryptophan and other biosystems.
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