Pub Date : 2024-12-17DOI: 10.1021/acs.chemmater.4c02160
A. K. M. Manjur Hossain, Joseph McBride, Masoumeh Mahmoudi Gahrouei, Sabin Gautam, Jefferson A. Carter, Piumi Indrachapa Samarawickrama, John F. Ackerman, Laura Rita de Sousa Oliveira, Jinke Tang, Jifa Tian, Brian M. Leonard
Recent research has demonstrated the potential for topological superconductivity, anisotropic Majorana bound states, optical nonlinearity, and enhanced electrochemical activity for transition metal dichalcogenides (TMDs) with a 2M structure. These unique TMD compounds exhibit metastability and, upon heating, undergo a transition to the thermodynamically stable 2H phase. The 2M phase is commonly made at high temperatures using traditional solid-state methods, and this metastability further complicates the growth of large 2M WS2 crystals. Herein, a novel synthetic method was developed, focusing on a molten salt reaction to synthesize large 2H crystals and then inducing transformation to the 2M phase through intercalation and thermal treatment. The 2H crystals were intercalated via a room-temperature sodium naphthalenide solution, producing a previously unreported Na-intercalated 2H WS2 phase. Thermal heating was required to facilitate the phase transition to the intercalated 2M crystal structure. This phase transition was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), electron dispersive X-ray spectroscopy (EDS), and Raman spectroscopy, which confirmed the synthesis of the intercalated 2M phase. Upon deintercalation, crystal and powder samples showed superconductivity with a Tc of 8.6–8.7 K, similar to previously reported values. The generality of this process was further demonstrated using alkali metal triethyl borohydride to intercalate 2H WS2 and produced the desired 2M phase. This novel synthetic method has broad implications for discovering metastable phases in other TMD families and layered materials. Separation of the intercalation and phase transition also has the potential to allow for large-scale synthesis of this technologically important phase with greater control over each step of the reaction.
{"title":"Intercalation-Induced Topotactic Phase Transformation of Tungsten Disulfide Crystals","authors":"A. K. M. Manjur Hossain, Joseph McBride, Masoumeh Mahmoudi Gahrouei, Sabin Gautam, Jefferson A. Carter, Piumi Indrachapa Samarawickrama, John F. Ackerman, Laura Rita de Sousa Oliveira, Jinke Tang, Jifa Tian, Brian M. Leonard","doi":"10.1021/acs.chemmater.4c02160","DOIUrl":"https://doi.org/10.1021/acs.chemmater.4c02160","url":null,"abstract":"Recent research has demonstrated the potential for topological superconductivity, anisotropic Majorana bound states, optical nonlinearity, and enhanced electrochemical activity for transition metal dichalcogenides (TMDs) with a 2M structure. These unique TMD compounds exhibit metastability and, upon heating, undergo a transition to the thermodynamically stable 2H phase. The 2M phase is commonly made at high temperatures using traditional solid-state methods, and this metastability further complicates the growth of large 2M WS<sub>2</sub> crystals. Herein, a novel synthetic method was developed, focusing on a molten salt reaction to synthesize large 2H crystals and then inducing transformation to the 2M phase through intercalation and thermal treatment. The 2H crystals were intercalated via a room-temperature sodium naphthalenide solution, producing a previously unreported Na-intercalated 2H WS<sub>2</sub> phase. Thermal heating was required to facilitate the phase transition to the intercalated 2M crystal structure. This phase transition was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), electron dispersive X-ray spectroscopy (EDS), and Raman spectroscopy, which confirmed the synthesis of the intercalated 2M phase. Upon deintercalation, crystal and powder samples showed superconductivity with a <i>T</i><sub>c</sub> of 8.6–8.7 K, similar to previously reported values. The generality of this process was further demonstrated using alkali metal triethyl borohydride to intercalate 2H WS<sub>2</sub> and produced the desired 2M phase. This novel synthetic method has broad implications for discovering metastable phases in other TMD families and layered materials. Separation of the intercalation and phase transition also has the potential to allow for large-scale synthesis of this technologically important phase with greater control over each step of the reaction.","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":"43 2 1","pages":""},"PeriodicalIF":8.6,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142832826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-17DOI: 10.1021/acs.chemmater.4c02271
Kristin L. Lewis, Jonathan D. Hoang, Michael F. Toney, Timothy J. White
Liquid crystalline elastomers (LCEs) are soft materials which disorder upon heating through the isotropic transition temperature. The order-disorder phase transition of LCEs results in a contraction of up to ∼50% along the aligned axis. Motivated by this distinctive stimuli-response, LCEs are increasingly considered as low-density actuators. Generally, LCEs are composed entirely of covalent bonds. Recently, we have prepared LCEs with intramesogenic supramolecular bonds from dimerized oxybenzoic acid derivatives and documented distinctive thermomechanical response in these supramolecular LCEs. Here, we report a detailed investigation of phase transitions in supramolecular LCEs by systematically varying the composition to affect the strength of the intermolecular interactions in the polymer network. The order-disorder phase transition is shown to be influenced by the conformation and dissociation of supramolecular dimers. Distinctly, this report isolates and details an LCE composition which undergoes an intermediate transition to an incommensurate phase at lower temperatures than the order-disorder transition.
{"title":"Order–Disorder Transition of Supramolecular Liquid Crystalline Elastomers","authors":"Kristin L. Lewis, Jonathan D. Hoang, Michael F. Toney, Timothy J. White","doi":"10.1021/acs.chemmater.4c02271","DOIUrl":"https://doi.org/10.1021/acs.chemmater.4c02271","url":null,"abstract":"Liquid crystalline elastomers (LCEs) are soft materials which disorder upon heating through the isotropic transition temperature. The order-disorder phase transition of LCEs results in a contraction of up to ∼50% along the aligned axis. Motivated by this distinctive stimuli-response, LCEs are increasingly considered as low-density actuators. Generally, LCEs are composed entirely of covalent bonds. Recently, we have prepared LCEs with intramesogenic supramolecular bonds from dimerized oxybenzoic acid derivatives and documented distinctive thermomechanical response in these supramolecular LCEs. Here, we report a detailed investigation of phase transitions in supramolecular LCEs by systematically varying the composition to affect the strength of the intermolecular interactions in the polymer network. The order-disorder phase transition is shown to be influenced by the conformation and dissociation of supramolecular dimers. Distinctly, this report isolates and details an LCE composition which undergoes an intermediate transition to an incommensurate phase at lower temperatures than the order-disorder transition.","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":"19 1","pages":""},"PeriodicalIF":8.6,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142832827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-16DOI: 10.1021/acs.chemmater.4c03025
Rohit Kumar Rohj, Animesh Bhui, Shaili Sett, Arindam Ghosh, Kanishka Biswas, D. D. Sarma
A comprehensive understanding of thermal transport is crucial for many applications, including heat dissipation systems, thermal barrier coatings, and harnessing potentials of thermoelectric materials. Here, we report an ultralow thermal conductivity, κ, in a p-type layered chalcogenide, TlCuZrSe3. Our investigation reveals that the anisotropic values of κ in two perpendicular directions in this compound vary between 0.88 and 0.41 Wm–1K–1 and 1.15–0.62 Wm–1K–1, respectively, over the temperature range of 295–600 K. The low-temperature specific heat data could only be explained by considering Einstein oscillator terms in addition to the conventional Debye model-based contributions, consistent with the presence of localized Tl1+ rattlers. The unique anisotropic crystal structure of TlCuZrSe3 and the rattling of Tl1+ ions lead to the generation of low-frequency phonons. These relatively flat optical phonon modes hybridize with acoustic phonons, giving rise to strong anharmonicity and phonon scattering channels. Raman spectroscopy confirms that these low-frequency phonon modes have extremely short lifetimes (∼1 ps), explaining the ultralow κ values, approaching the disordered limit, in this highly crystalline material.
{"title":"Ultralow Thermal Conductivity Approaching the Disordered Limit in Crystalline TlCuZrSe3","authors":"Rohit Kumar Rohj, Animesh Bhui, Shaili Sett, Arindam Ghosh, Kanishka Biswas, D. D. Sarma","doi":"10.1021/acs.chemmater.4c03025","DOIUrl":"https://doi.org/10.1021/acs.chemmater.4c03025","url":null,"abstract":"A comprehensive understanding of thermal transport is crucial for many applications, including heat dissipation systems, thermal barrier coatings, and harnessing potentials of thermoelectric materials. Here, we report an ultralow thermal conductivity, κ, in a p-type layered chalcogenide, TlCuZrSe<sub>3</sub>. Our investigation reveals that the anisotropic values of κ in two perpendicular directions in this compound vary between 0.88 and 0.41 Wm<sup>–1</sup>K<sup>–1</sup> and 1.15–0.62 Wm<sup>–1</sup>K<sup>–1</sup>, respectively, over the temperature range of 295–600 K. The low-temperature specific heat data could only be explained by considering Einstein oscillator terms in addition to the conventional Debye model-based contributions, consistent with the presence of localized Tl<sup>1+</sup> rattlers. The unique anisotropic crystal structure of TlCuZrSe<sub>3</sub> and the rattling of Tl<sup>1+</sup> ions lead to the generation of low-frequency phonons. These relatively flat optical phonon modes hybridize with acoustic phonons, giving rise to strong anharmonicity and phonon scattering channels. Raman spectroscopy confirms that these low-frequency phonon modes have extremely short lifetimes (∼1 ps), explaining the ultralow κ values, approaching the disordered limit, in this highly crystalline material.","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":"4 1","pages":""},"PeriodicalIF":8.6,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142832472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-16DOI: 10.1021/acs.chemmater.4c02756
Xiliang Lian, Damien Dambournet, Mathieu Salanne
Solid-state ionic conductors are of primary importance for the design of tomorrow’s batteries. In lithium- or sodium-ion-based materials, the alkali cations diffuse through three-dimensional channels consisting of interconnected tetrahedral or octahedral sites with low free energy barriers between them. Fluoride ion conductors stand out in this landscape since the materials with the highest conductivities belong to the MSnF4 family (in which M2+ is a divalent cation), whose structure is layered and characterized by double-layers of Sn2+ and M2+ cations along a given direction. Importantly, these materials display stereoactive electron lone pairs (LPs) that seemingly play an important role not only in stabilizing the Sn–Sn layer but also in modulating the fluoride ion diffusive behavior. However, despite previous experimental and simulation studies, the involvement of the LPs in the fluoride ion conduction mechanism remains to be quantitatively understood. In this work, we simulate the BaSnF4 tetragonal structure using machine learning-based molecular dynamics, in which the interaction potential is trained on density functional theory data. We investigated the role of the Sn–LP–Sn layer in lowering the diffusion energy landscape. In particular, we show how the F– ions jump across this layer and occur much more frequently than in the Ba–F–Ba one, resulting in the formation of vacancies in the Ba–Sn layers. Concurrently, the LP stereochemical activity fluctuates to accommodate the F ions jumping. In addition, the presence of the LP layer enhances the flexibility of the Sn ions, which leads to an increase in two-dimensional diffusion by several orders of magnitude. These results contribute to our understanding of the interplay between LPs and ionic diffusion, helping to explain the good performance of the material in fluoride-ion batteries.
{"title":"Stereoactive Electron Lone Pairs Facilitate Fluoride Ion Diffusion in Tetragonal BaSnF4","authors":"Xiliang Lian, Damien Dambournet, Mathieu Salanne","doi":"10.1021/acs.chemmater.4c02756","DOIUrl":"https://doi.org/10.1021/acs.chemmater.4c02756","url":null,"abstract":"Solid-state ionic conductors are of primary importance for the design of tomorrow’s batteries. In lithium- or sodium-ion-based materials, the alkali cations diffuse through three-dimensional channels consisting of interconnected tetrahedral or octahedral sites with low free energy barriers between them. Fluoride ion conductors stand out in this landscape since the materials with the highest conductivities belong to the MSnF<sub>4</sub> family (in which M<sup>2+</sup> is a divalent cation), whose structure is layered and characterized by double-layers of Sn<sup>2+</sup> and M<sup>2+</sup> cations along a given direction. Importantly, these materials display stereoactive electron lone pairs (LPs) that seemingly play an important role not only in stabilizing the Sn–Sn layer but also in modulating the fluoride ion diffusive behavior. However, despite previous experimental and simulation studies, the involvement of the LPs in the fluoride ion conduction mechanism remains to be quantitatively understood. In this work, we simulate the BaSnF<sub>4</sub> tetragonal structure using machine learning-based molecular dynamics, in which the interaction potential is trained on density functional theory data. We investigated the role of the Sn–LP–Sn layer in lowering the diffusion energy landscape. In particular, we show how the F<sup>–</sup> ions jump across this layer and occur much more frequently than in the Ba–F–Ba one, resulting in the formation of vacancies in the Ba–Sn layers. Concurrently, the LP stereochemical activity fluctuates to accommodate the F ions jumping. In addition, the presence of the LP layer enhances the flexibility of the Sn ions, which leads to an increase in two-dimensional diffusion by several orders of magnitude. These results contribute to our understanding of the interplay between LPs and ionic diffusion, helping to explain the good performance of the material in fluoride-ion batteries.","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":"88 1","pages":""},"PeriodicalIF":8.6,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142832894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-16DOI: 10.1021/acs.chemmater.4c02740
Junsu Lee, Minkyoung Kim, Ji Hee Pi, Myung-Ho Choi, Kang Min Ok, Kyu Hyoung Lee, Tae-Soo You
Four quaternary Zintl phase solid-solutions in the Ca9Cd3+x–yMx+ySb9 (M = Cu, Zn) system were successfully synthesized, and their crystal structures were characterized by using both powder X-ray and single-crystal X-ray diffractions. All title compounds adopted the Ca9Zn3.1In0.9Sb9-type phase, featuring three-dimensional anionic frameworks composed of tetrahedral [MSb4] and tricoordinated [MSb3] moieties interconnected via vertex-sharing. Detailed structural analyses revealed that various types of partial and mixed occupations existed at the M sites, and the Zn2 site in Ca9Cd2.65(1)Zn1.84(2)Sb9 exhibited a trigonal pyramid geometry, distinct from the simple planar geometry observed in parental Ca9Zn3.1In0.9Sb9. The density of states (DOS) analyses revealed successful p-type doping in the Cu-containing compound, indicated by a shift in the Fermi level and an increase in the hole carrier concentration. Crystal orbital Hamilton population curves displayed optimized interatomic interactions between neighboring anionic elements, maintaining structural stability despite a slight increase in the DOS level. Thermoelectric property measurements were conducted for the first time on the Ca9Zn3.1In0.9Sb9-type phase. The results demonstrated that the Zn-containing compounds exhibited higher Seebeck coefficients and lower thermal conductivities, resulting in larger ZT values compared to the Cu-containing compounds. The highest ZT value of 0.70 at 775 K was observed for Ca9Cd4.05Zn0.45Sb9.
{"title":"Insights into the Crystal Structure and Thermoelectric Properties of the Zintl Phase Ca9Cd3+x–yMx+ySb9 (M = Cu, Zn) System","authors":"Junsu Lee, Minkyoung Kim, Ji Hee Pi, Myung-Ho Choi, Kang Min Ok, Kyu Hyoung Lee, Tae-Soo You","doi":"10.1021/acs.chemmater.4c02740","DOIUrl":"https://doi.org/10.1021/acs.chemmater.4c02740","url":null,"abstract":"Four quaternary Zintl phase solid-solutions in the Ca<sub>9</sub>Cd<sub>3+<i>x–y</i></sub>M<sub><i>x+y</i></sub>Sb<sub>9</sub> (M = Cu, Zn) system were successfully synthesized, and their crystal structures were characterized by using both powder X-ray and single-crystal X-ray diffractions. All title compounds adopted the Ca<sub>9</sub>Zn<sub>3.1</sub>In<sub>0.9</sub>Sb<sub>9</sub>-type phase, featuring three-dimensional anionic frameworks composed of tetrahedral [MSb<sub>4</sub>] and tricoordinated [MSb<sub>3</sub>] moieties interconnected via vertex-sharing. Detailed structural analyses revealed that various types of partial and mixed occupations existed at the M sites, and the Zn2 site in Ca<sub>9</sub>Cd<sub>2.65(1)</sub>Zn<sub>1.84(2)</sub>Sb<sub>9</sub> exhibited a trigonal pyramid geometry, distinct from the simple planar geometry observed in parental Ca<sub>9</sub>Zn<sub>3.1</sub>In<sub>0.9</sub>Sb<sub>9</sub>. The density of states (DOS) analyses revealed successful <i>p</i>-type doping in the Cu-containing compound, indicated by a shift in the Fermi level and an increase in the hole carrier concentration. Crystal orbital Hamilton population curves displayed optimized interatomic interactions between neighboring anionic elements, maintaining structural stability despite a slight increase in the DOS level. Thermoelectric property measurements were conducted for the first time on the Ca<sub>9</sub>Zn<sub>3.1</sub>In<sub>0.9</sub>Sb<sub>9</sub>-type phase. The results demonstrated that the Zn-containing compounds exhibited higher Seebeck coefficients and lower thermal conductivities, resulting in larger <i>ZT</i> values compared to the Cu-containing compounds. The highest <i>ZT</i> value of 0.70 at 775 K was observed for Ca<sub>9</sub>Cd<sub>4.05</sub>Zn<sub>0.45</sub>Sb<sub>9</sub>.","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":"24 1","pages":""},"PeriodicalIF":8.6,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142832471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-16DOI: 10.1021/acs.chemmater.4c02541
Shikai Liu, Chuqiao Shi, Chaokai Xu, Haichuan Zhang, Wenqi Li, Valentín Briega-Martos, Qian He, Yimo Han, Yao Yang
CO2 reduction reaction (CO2RR) facilitates the sustainable synthesis of fuels and chemicals. Although copper (Cu) enables CO2-to-multicarbon product (C2+) conversion, Cu-based electrocatalysts, particularly nanocatalysts, face challenges in poor selectivity and stability owing to the highly dynamic nature of Cu atoms under reaction conditions. Core–shell structures present a promising approach to address these issues by modulating the Cu overlayer–substrate interactions with atomic-level precision. Here, we report on Pd@Cu core–shell structures with atomically thin and nanometer-thick Cu overlayers on single-crystal Pd nanocubes with {100} facets promoting the CO2-to-C2+ conversion. The microstructures and surface compositions at the atomically sharp Pd/Cu interface were investigated by atomic-scale scanning transmission electron microscopy (STEM) imaging and electron energy-loss spectroscopy (EELS). Our results reveal that atomic-layer Cu epitaxially grows on Pd and adapts to the lattice of the Pd substrate. The reaction-driven migration of atomic-layer Cu is effectively suppressed on Pd due to the strong Cu–Pd interaction. While Pd only reduces CO2 to C1 products, atomic-layer Cu on Pd can initiate the C2+ production during the CO2RR. Thick Cu overlayers (∼15 nm) on Pd further enhance the C2+ faradaic efficiency while undergoing significant structural reconstruction, with only the 2–3 nm Cu layers near the Pd surface remaining stable and resistant to Cu migration after the CO2RR. We anticipate that Pd@Cu core–shell structures with intermediate Cu shell thickness hold significant potential for enhancing C2+ selectivity while maintaining high stability of nanocatalysts for CO2 reduction to liquid fuels.
二氧化碳还原反应（CO2RR）有助于燃料和化学品的可持续合成。虽然铜（Cu）可以实现 CO2 到多碳产物（C2+）的转化，但由于铜原子在反应条件下的高度动态性质，铜基电催化剂（尤其是纳米催化剂）面临着选择性差和稳定性低的挑战。核壳结构以原子级的精度调节铜覆盖层与基底的相互作用，为解决这些问题提供了一种很有前景的方法。在此，我们报告了 Pd@Cu 核壳结构，该结构在具有 {100} 面的单晶 Pd 纳米管上具有原子级厚度和纳米级厚度的铜覆盖层，可促进 CO2 到 C2+ 的转化。我们通过原子尺度扫描透射电子显微镜（STEM）成像和电子能量损失光谱（EELS）研究了原子尖锐的钯/铜界面的微观结构和表面成分。我们的研究结果表明，原子层铜在钯上外延生长并适应钯基底的晶格。由于铜与钯之间的强相互作用，原子层铜在钯上的反应驱动迁移被有效抑制。虽然 Pd 只能将 CO2 还原成 C1 产物，但 Pd 上的原子层 Cu 却能在 CO2RR 过程中启动 C2+ 生成。Pd 上的厚铜覆盖层（∼15 nm）进一步提高了 C2+ 的远达效率，同时经历了显著的结构重构，只有靠近 Pd 表面的 2-3 nm 铜层在 CO2RR 之后保持稳定并能抵抗铜迁移。我们预计，具有中等铜壳厚度的 Pd@Cu 核壳结构在提高 C2+ 选择性方面具有巨大潜力，同时还能保持用于将 CO2 还原成液体燃料的纳米催化剂的高稳定性。
{"title":"Epitaxial Growth of Atomic-Layer Cu on Pd Nanocatalysts for Electrochemical CO2 Reduction","authors":"Shikai Liu, Chuqiao Shi, Chaokai Xu, Haichuan Zhang, Wenqi Li, Valentín Briega-Martos, Qian He, Yimo Han, Yao Yang","doi":"10.1021/acs.chemmater.4c02541","DOIUrl":"https://doi.org/10.1021/acs.chemmater.4c02541","url":null,"abstract":"CO<sub>2</sub> reduction reaction (CO<sub>2</sub>RR) facilitates the sustainable synthesis of fuels and chemicals. Although copper (Cu) enables CO<sub>2</sub>-to-multicarbon product (C<sub>2+</sub>) conversion, Cu-based electrocatalysts, particularly nanocatalysts, face challenges in poor selectivity and stability owing to the highly dynamic nature of Cu atoms under reaction conditions. Core–shell structures present a promising approach to address these issues by modulating the Cu overlayer–substrate interactions with atomic-level precision. Here, we report on Pd@Cu core–shell structures with atomically thin and nanometer-thick Cu overlayers on single-crystal Pd nanocubes with {100} facets promoting the CO<sub>2</sub>-to-C<sub>2+</sub> conversion. The microstructures and surface compositions at the atomically sharp Pd/Cu interface were investigated by atomic-scale scanning transmission electron microscopy (STEM) imaging and electron energy-loss spectroscopy (EELS). Our results reveal that atomic-layer Cu epitaxially grows on Pd and adapts to the lattice of the Pd substrate. The reaction-driven migration of atomic-layer Cu is effectively suppressed on Pd due to the strong Cu–Pd interaction. While Pd only reduces CO<sub>2</sub> to C<sub>1</sub> products, atomic-layer Cu on Pd can initiate the C<sub>2+</sub> production during the CO<sub>2</sub>RR. Thick Cu overlayers (∼15 nm) on Pd further enhance the C<sub>2+</sub> faradaic efficiency while undergoing significant structural reconstruction, with only the 2–3 nm Cu layers near the Pd surface remaining stable and resistant to Cu migration after the CO<sub>2</sub>RR. We anticipate that Pd@Cu core–shell structures with intermediate Cu shell thickness hold significant potential for enhancing C<sub>2+</sub> selectivity while maintaining high stability of nanocatalysts for CO<sub>2</sub> reduction to liquid fuels.","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":"97 1","pages":""},"PeriodicalIF":8.6,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142832828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-16DOI: 10.1021/acs.chemmater.4c02697
Ye Zhou, Xiaoyue Duan, Xin Xu, Poe Ei Phyu Win, Shi-Bin Ren, Jiong Wang
The hangman structure plays a critical role in determining the reaction rates of molecular CO2 electrocatalysis through constructing pendant functional groups in secondary coordination spheres of metal active sites. However, achieving hangman structures commonly requires complicated asymmetric synthesis. It is necessary to search for simple alternative strategies to develop hangman molecular electrocatalysis with realization of the concept of green chemistry. In this work, we report the synthesis of hangman molecular electrocatalysts based on the noncovalent π–π interaction between cobalt (Co) phthalocyanine nanotubes and 1-aminopyrene. It promoted the kinetics of interfacial inner and outer sphere electron transfer on the complex and chemisorption of *COOH and *CO species through interaction with both Co sites and pendant amine groups in a bridge geometry. The resultant Co sites afforded a very high turnover frequency of 4.37 s–1 at an overpotential of 0.29 V for electrochemical CO2 to CO conversion and thus afforded an industrial interest current density being steady at 350 mA cm–2.
悬挂结构通过在金属活性位点的次级配位层中构建悬挂官能团，在决定分子 CO2 电催化反应速率方面发挥着至关重要的作用。然而，实现悬臂结构通常需要复杂的不对称合成。因此，有必要寻找简单的替代策略，在实现绿色化学理念的前提下开发悬臂分子电催化技术。在这项工作中，我们报道了基于钴（Co）酞菁纳米管和 1-aminopyrene 之间的非共价 π-π 相互作用合成的悬臂分子电催化剂。它通过与 Co 位点和桥式几何中的垂胺基团相互作用，促进了复合物上界面内外球电子转移动力学以及 *COOH 和 *CO 物种的化学吸附。由此产生的 Co 位点在 0.29 V 的过电位条件下，将 CO2 电化学转化为 CO 的周转频率高达 4.37 s-1，从而使电流密度稳定在 350 mA cm-2 的工业水平。
{"title":"Noncovalent Construction of Hangman Cobalt Phthalocyanine for Enhanced Electrochemical Carbon Dioxide Reduction","authors":"Ye Zhou, Xiaoyue Duan, Xin Xu, Poe Ei Phyu Win, Shi-Bin Ren, Jiong Wang","doi":"10.1021/acs.chemmater.4c02697","DOIUrl":"https://doi.org/10.1021/acs.chemmater.4c02697","url":null,"abstract":"The hangman structure plays a critical role in determining the reaction rates of molecular CO<sub>2</sub> electrocatalysis through constructing pendant functional groups in secondary coordination spheres of metal active sites. However, achieving hangman structures commonly requires complicated asymmetric synthesis. It is necessary to search for simple alternative strategies to develop hangman molecular electrocatalysis with realization of the concept of green chemistry. In this work, we report the synthesis of hangman molecular electrocatalysts based on the noncovalent π–π interaction between cobalt (Co) phthalocyanine nanotubes and 1-aminopyrene. It promoted the kinetics of interfacial inner and outer sphere electron transfer on the complex and chemisorption of *COOH and *CO species through interaction with both Co sites and pendant amine groups in a bridge geometry. The resultant Co sites afforded a very high turnover frequency of 4.37 s<sup>–1</sup> at an overpotential of 0.29 V for electrochemical CO<sub>2</sub> to CO conversion and thus afforded an industrial interest current density being steady at 350 mA cm<sup>–2</sup>.","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":"11 1","pages":""},"PeriodicalIF":8.6,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142832829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The utilization of earth-abundant and high-capacity sulfur in solid-state batteries presents a promising strategy to circumvent the use of rare transition metals and enhance achievable specific energy. However, numerous challenges remain. The transport limitation within the cathode composite, particularly with sulfide electrolytes during charging, has been identified as a major degradation mechanism in solid-state Li–S batteries. This degradation is linked to electrolyte oxidation and a concomitant reduction in the effective ionic conductivity of the cathode composite. Inspired by the sufficiently high oxidation stability of halide-based electrolytes, we investigated their compatibility with solid-state Li–S batteries in this work. The electrochemical stability of halides in contact with conductive additives, the stability window of fast ion transport in the composite electrodes, and chemical compatibility with sulfur-active materials (e.g., S and Li2S), in addition to the cyclability of the halide-based composite electrodes, are explored. Three halides were employed as model electrolytes: Li3InCl6, Li3YCl6, and Li3YBr6. Despite its high oxidation stability, Li3InCl6 exhibited rapid degradation due to electrolyte reduction. The composite with Li3YCl6 lost its capacity because of chemical incompatibility, especially with Li2S, resulting in the formation of LiYS2 at the interface. In contrast, Li3YBr6 demonstrated superior performance, maintaining a capacity of 1100 mAh gS–1 for 20 cycles (normalized to the sulfur content in the cathode material). This study elucidates the degradation mechanisms of halide-based solid-state Li–S batteries and proposes potential design strategies to mitigate chemical incompatibility issues.
{"title":"Compatibility of Halide Electrolytes in Solid-State Li–S Battery Cathodes","authors":"Shoma Yanagihara, Jan Huebner, Zheng Huang, Atsushi Inoishi, Hirofumi Akamatsu, Katsuro Hayashi, Saneyuki Ohno","doi":"10.1021/acs.chemmater.4c02159","DOIUrl":"https://doi.org/10.1021/acs.chemmater.4c02159","url":null,"abstract":"The utilization of earth-abundant and high-capacity sulfur in solid-state batteries presents a promising strategy to circumvent the use of rare transition metals and enhance achievable specific energy. However, numerous challenges remain. The transport limitation within the cathode composite, particularly with sulfide electrolytes during charging, has been identified as a major degradation mechanism in solid-state Li–S batteries. This degradation is linked to electrolyte oxidation and a concomitant reduction in the effective ionic conductivity of the cathode composite. Inspired by the sufficiently high oxidation stability of halide-based electrolytes, we investigated their compatibility with solid-state Li–S batteries in this work. The electrochemical stability of halides in contact with conductive additives, the stability window of fast ion transport in the composite electrodes, and chemical compatibility with sulfur-active materials (e.g., S and Li<sub>2</sub>S), in addition to the cyclability of the halide-based composite electrodes, are explored. Three halides were employed as model electrolytes: Li<sub>3</sub>InCl<sub>6</sub>, Li<sub>3</sub>YCl<sub>6</sub>, and Li<sub>3</sub>YBr<sub>6</sub>. Despite its high oxidation stability, Li<sub>3</sub>InCl<sub>6</sub> exhibited rapid degradation due to electrolyte reduction. The composite with Li<sub>3</sub>YCl<sub>6</sub> lost its capacity because of chemical incompatibility, especially with Li<sub>2</sub>S, resulting in the formation of LiYS<sub>2</sub> at the interface. In contrast, Li<sub>3</sub>YBr<sub>6</sub> demonstrated superior performance, maintaining a capacity of 1100 mAh g<sub>S</sub><sup>–1</sup> for 20 cycles (normalized to the sulfur content in the cathode material). This study elucidates the degradation mechanisms of halide-based solid-state Li–S batteries and proposes potential design strategies to mitigate chemical incompatibility issues.","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":"244 1","pages":""},"PeriodicalIF":8.6,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142832469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-16DOI: 10.1021/acs.chemmater.4c02855
Camilla Tacconis, Sunita Dey, Carson D. McLaughlin, Moulay Tahar Sougrati, Christopher A. O’Keefe, Iuliia Mikulska, Clare P. Grey, Siân E. Dutton
We investigate magnesium–iron pyroborate MgFeB2O5 as a potential cathode material for rechargeable magnesium-ion batteries. Synchrotron powder X-ray diffraction and Mössbauer spectroscopy confirm its successful synthesis and iron stabilization in the high-spin Fe(II) state. Initial electrochemical testing against a lithium metal anode yields a first charge capacity near the theoretical value (147.45 mAh·g–1), suggesting MgFeB2O5 as a promising cathode candidate. However, multimodal analyses, including scanning electron microscopy energy-dispersive X-ray (SEM-EDS) analysis, operando X-ray absorption near edge spectroscopy (XANES), and Mössbauer spectroscopy, reveal the absence of any Fe redox reactions. Instead, we propose that the source of the observed capacity involves the irreversible reaction of a small (4–7 wt%) Fe metal impurity. These findings highlight the need for diverse characterization techniques in evaluating the performance of new Mg cathode materials, since promising initial cycling may be caused by competing side reactions rather than Mg (de)intercalation.
我们研究了作为可充电镁离子电池潜在阴极材料的镁铁硼酸盐 MgFeB2O5。同步辐射粉末 X 射线衍射和 Mössbauer 光谱证实了它的成功合成和高自旋铁（II）态铁的稳定。针对锂金属阳极的初步电化学测试得出的首次充电容量接近理论值（147.45 mAh-g-1），表明 MgFeB2O5 是一种很有前途的阴极候选材料。然而，包括扫描电子显微镜能量色散 X 射线（SEM-EDS）分析、操作性 X 射线吸收近缘光谱（XANES）和莫斯鲍尔光谱在内的多模态分析表明，其中不存在任何铁氧化还原反应。相反，我们认为所观察到的容量来源于少量（4-7 wt%）铁金属杂质的不可逆反应。这些发现突出表明，在评估新型镁阴极材料的性能时，需要采用不同的表征技术，因为初期循环的良好表现可能是由竞争性副反应而不是镁（脱）插层引起的。
{"title":"Role of Fe Impurity Reactions in the Electrochemical Properties of MgFeB2O5","authors":"Camilla Tacconis, Sunita Dey, Carson D. McLaughlin, Moulay Tahar Sougrati, Christopher A. O’Keefe, Iuliia Mikulska, Clare P. Grey, Siân E. Dutton","doi":"10.1021/acs.chemmater.4c02855","DOIUrl":"https://doi.org/10.1021/acs.chemmater.4c02855","url":null,"abstract":"We investigate magnesium–iron pyroborate MgFeB<sub>2</sub>O<sub>5</sub> as a potential cathode material for rechargeable magnesium-ion batteries. Synchrotron powder X-ray diffraction and Mössbauer spectroscopy confirm its successful synthesis and iron stabilization in the high-spin Fe(II) state. Initial electrochemical testing against a lithium metal anode yields a first charge capacity near the theoretical value (147.45 mAh·g<sup>–1</sup>), suggesting MgFeB<sub>2</sub>O<sub>5</sub> as a promising cathode candidate. However, multimodal analyses, including scanning electron microscopy energy-dispersive X-ray (SEM-EDS) analysis, <i>operando</i> X-ray absorption near edge spectroscopy (XANES), and Mössbauer spectroscopy, reveal the absence of any Fe redox reactions. Instead, we propose that the source of the observed capacity involves the irreversible reaction of a small (4–7 wt%) Fe metal impurity. These findings highlight the need for diverse characterization techniques in evaluating the performance of new Mg cathode materials, since promising initial cycling may be caused by competing side reactions rather than Mg (de)intercalation.","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":"47 1","pages":""},"PeriodicalIF":8.6,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142832470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-13DOI: 10.1021/acs.chemmater.4c01732
Daniel D. Robertson, Charlene Z. Salamat, David J. Pe, Helen Cumberbatch, David N. Agyeman-Budu, Johanna Nelson Weker, Sarah H. Tolbert
Electrochemically-formed disordered rock salt compounds are an emerging class of Li-ion electrode materials for fast-charging energy storage. However, the specific factors that govern the formation process and the resulting charge storage performance are not well understood. Here, we characterize the transformation mechanism and charge storage properties of an electrochemically-formed disordered rock salt from V9Mo6O40 (VMO). The crystal structure of VMO has similar motifs to that of α-V2O5, a well-studied analogue, but VMO has less mechanical flexibility due to additional corner-sharing octahedra in its structure. As a result, VMO undergoes a single-step transformation pathway, which we characterize through operando X-ray diffraction, and forms an unusual highly distorted lamellar microstructure, as we show with high-resolution transmission electron microscopy. The resulting LixVMO material shows fast charging and other electrochemical characteristics and performance typical of many nanomaterials, even though the material is composed of relatively large particles.
{"title":"Electrochemically-Formed Disordered Rock Salt ω-LixV9Mo6O40 as a Fast-Charging Li-Ion Electrode Material","authors":"Daniel D. Robertson, Charlene Z. Salamat, David J. Pe, Helen Cumberbatch, David N. Agyeman-Budu, Johanna Nelson Weker, Sarah H. Tolbert","doi":"10.1021/acs.chemmater.4c01732","DOIUrl":"https://doi.org/10.1021/acs.chemmater.4c01732","url":null,"abstract":"Electrochemically-formed disordered rock salt compounds are an emerging class of Li-ion electrode materials for fast-charging energy storage. However, the specific factors that govern the formation process and the resulting charge storage performance are not well understood. Here, we characterize the transformation mechanism and charge storage properties of an electrochemically-formed disordered rock salt from V<sub>9</sub>Mo<sub>6</sub>O<sub>40</sub> (VMO). The crystal structure of VMO has similar motifs to that of α-V<sub>2</sub>O<sub>5</sub>, a well-studied analogue, but VMO has less mechanical flexibility due to additional corner-sharing octahedra in its structure. As a result, VMO undergoes a single-step transformation pathway, which we characterize through operando X-ray diffraction, and forms an unusual highly distorted lamellar microstructure, as we show with high-resolution transmission electron microscopy. The resulting Li<sub><i>x</i></sub>VMO material shows fast charging and other electrochemical characteristics and performance typical of many nanomaterials, even though the material is composed of relatively large particles.","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":"56 1","pages":""},"PeriodicalIF":8.6,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142816126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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