Pub Date : 2025-04-26DOI: 10.1021/acs.jpcc.4c08512
Usama Saleem, Shaama Mallikarjun Sharada
We investigate the high-temperature evolution of the metal–support interface in atomically dispersed catalysts to probe the dynamical evolution of the metal atom. Since high computational costs limit the time scales of ab initio molecular dynamics (AIMD) trajectories to a few picoseconds, we deploy a machine learned interatomic potential (MLIP), trained on AIMD data, using the FLARE program. We generate multiple trajectories spanning at least 50 ps each for atomically dispersed Pt on rutile TiO2 (110), initiated at different positions on the stoichiometric surface. We find that the motion of Pt is subdiffusive (not Brownian) in most cases, quantified by the parameters constituting the fractional Fokker-Planck equation. The subdiffusive behavior originates in strong interactions of Pt with bridging oxygen atoms of the support. Several trajectories show that Pt mobility is quenched when it coordinates with two bridging oxygen atoms to form a near-linear O–Pt–O complex. Diffusion that resembles Brownian motion is observed only at the highest simulation temperature examined (1000 K) for sites at which Pt is far from a bridging oxygen. The study therefore shows that in the absence of surface defects or adsorbates, the thermal stability of the metal atom is determined by coordination with bridging oxygen atoms.
{"title":"Anomalous Diffusion of Metal Atoms on Oxide Surfaces: A Machine Learning Molecular Dynamics Study of Pt1/TiO2","authors":"Usama Saleem, Shaama Mallikarjun Sharada","doi":"10.1021/acs.jpcc.4c08512","DOIUrl":"https://doi.org/10.1021/acs.jpcc.4c08512","url":null,"abstract":"We investigate the high-temperature evolution of the metal–support interface in atomically dispersed catalysts to probe the dynamical evolution of the metal atom. Since high computational costs limit the time scales of ab initio molecular dynamics (AIMD) trajectories to a few picoseconds, we deploy a machine learned interatomic potential (MLIP), trained on AIMD data, using the FLARE program. We generate multiple trajectories spanning at least 50 ps each for atomically dispersed Pt on rutile TiO<sub>2</sub> (110), initiated at different positions on the stoichiometric surface. We find that the motion of Pt is subdiffusive (not Brownian) in most cases, quantified by the parameters constituting the fractional Fokker-Planck equation. The subdiffusive behavior originates in strong interactions of Pt with bridging oxygen atoms of the support. Several trajectories show that Pt mobility is quenched when it coordinates with two bridging oxygen atoms to form a near-linear O–Pt–O complex. Diffusion that resembles Brownian motion is observed only at the highest simulation temperature examined (1000 K) for sites at which Pt is far from a bridging oxygen. The study therefore shows that in the absence of surface defects or adsorbates, the thermal stability of the metal atom is determined by coordination with bridging oxygen atoms.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"18 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143876259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-25DOI: 10.1021/acs.jpcc.5c00460
Gaëlle Bouder, Hamza Bouhani, Hervé Martinez, Philippe Carbonniere
Lithium metal anodes hold great promise for high-energy batteries but are hindered by uncontrolled dendrite growth and unstable solid-electrolyte interphase (SEI) formation. This study explores the early molecular interactions at the lithium-electrolyte interface, providing theoretical insights into potential reaction pathways prior to SEI formation. In the present work, ab initio molecular dynamics and density functional theory simulations are employed to investigate the interactions and decomposition of solid polymer electrolyte molecules on lithium metal anode surfaces. The electrolyte comprises polyvinylidene fluoride, fluoroethylene carbonate, and lithium bis(fluorosulfonyl)imide. By analyzing adsorption energies, Bader charges, charge density differences, and projected density of states, we identify the most favored pathways of decomposition. A study of the decomposition of a fluorinated electrolyte at the surface of two lithium electrode planes, Li(100) and Li(110), was conducted. It was found, through differences in relative energies, that reduction pathways on the Li(110) surface are more favorable than those on the Li(100) surface. Specifically, for the system involving the solvent, the salt, and the polymer, it was found to be more favorable by 0.16, 0.23, and 0.26 eV, respectively. Moreover, the simulations unveil the formation of crucial SEI components, such as LiF, which is known to promote uniform lithium deposition and mitigate dendrite growth. The good agreement between our findings and previous experimental studies underscores the robustness of the employed theoretical approach. The insights gained from this comprehensive atomistic study provide valuable guidance for optimizing solid polymer electrolyte chemistry and structure to enable high-performance lithium metal batteries.
{"title":"Atomistic Insights into the Decomposition of Solid Polymer Electrolyte Molecules on Lithium Metal Anode: A Combined DFT and AIMD Study","authors":"Gaëlle Bouder, Hamza Bouhani, Hervé Martinez, Philippe Carbonniere","doi":"10.1021/acs.jpcc.5c00460","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c00460","url":null,"abstract":"Lithium metal anodes hold great promise for high-energy batteries but are hindered by uncontrolled dendrite growth and unstable solid-electrolyte interphase (SEI) formation. This study explores the early molecular interactions at the lithium-electrolyte interface, providing theoretical insights into potential reaction pathways prior to SEI formation. In the present work, ab initio molecular dynamics and density functional theory simulations are employed to investigate the interactions and decomposition of solid polymer electrolyte molecules on lithium metal anode surfaces. The electrolyte comprises polyvinylidene fluoride, fluoroethylene carbonate, and lithium bis(fluorosulfonyl)imide. By analyzing adsorption energies, Bader charges, charge density differences, and projected density of states, we identify the most favored pathways of decomposition. A study of the decomposition of a fluorinated electrolyte at the surface of two lithium electrode planes, Li(100) and Li(110), was conducted. It was found, through differences in relative energies, that reduction pathways on the Li(110) surface are more favorable than those on the Li(100) surface. Specifically, for the system involving the solvent, the salt, and the polymer, it was found to be more favorable by 0.16, 0.23, and 0.26 eV, respectively. Moreover, the simulations unveil the formation of crucial SEI components, such as LiF, which is known to promote uniform lithium deposition and mitigate dendrite growth. The good agreement between our findings and previous experimental studies underscores the robustness of the employed theoretical approach. The insights gained from this comprehensive atomistic study provide valuable guidance for optimizing solid polymer electrolyte chemistry and structure to enable high-performance lithium metal batteries.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"17 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143876260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-25DOI: 10.1021/acs.jpcc.4c08473
Ying Wang, Christina Alexakos, Tobias J. Zaidman, Jennifer Houghton, Zixuan Xie, David A. Fike, Young-Shin Jun
Carbonation of alkaline earth metals (e.g., magnesium (Mg)) and sulfidation of nickel (Ni) are promising methods to achieve concurrent carbon mineralization and selective Ni recovery. However, the coexistence of alkaline earth metals and Ni from silicate ores or mining wastewater complicates the carbonation and sulfidation owing to cation coprecipitation. To better understand simultaneous metal carbonation and Ni-sulfide formation, we used Mg- and Ni-containing solutions and systematically investigated the Mg and Ni coprecipitates’ phase transformation during sequential/concurrent carbonation and sulfidation. During a single carbonation process, hydromagnesite dehydrated and formed magnesite over time. Nickel bicarbonate formed and became a Mg–Ni carbonate solid solution because of their similar ionic radii. During a single sulfidation process, the pH did not affect Ni-sulfide formation, but it controlled Mg behavior. Specifically, at pH 9.6, brucite formed, while at pH 7.8, Mg2+ remained in the solution. For the sequential carbonation–sulfidation process, Ni-carbonate formed during carbonation converted to Ni-sulfide because of the low Ni-sulfide Ksp. For the sulfidation–carbonation process, Ni-sulfide remained the same even after carbonation and Mg-carbonate precipitates. For the concurrent carbonation and sulfidation process, Mg-carbonate and Ni-sulfide formed simultaneously. This study develops a scientific foundation of carbonation and sulfidation processes, benefiting coupled CO2 storage and sulfide-enabled resource recovery.
{"title":"Carbonation and Sulfidation of Mg- and Ni-Containing Solutions: Implications for Carbon Mineralization and Critical Element Recovery","authors":"Ying Wang, Christina Alexakos, Tobias J. Zaidman, Jennifer Houghton, Zixuan Xie, David A. Fike, Young-Shin Jun","doi":"10.1021/acs.jpcc.4c08473","DOIUrl":"https://doi.org/10.1021/acs.jpcc.4c08473","url":null,"abstract":"Carbonation of alkaline earth metals (<i>e.g.</i>, magnesium (Mg)) and sulfidation of nickel (Ni) are promising methods to achieve concurrent carbon mineralization and selective Ni recovery. However, the coexistence of alkaline earth metals and Ni from silicate ores or mining wastewater complicates the carbonation and sulfidation owing to cation coprecipitation. To better understand simultaneous metal carbonation and Ni-sulfide formation, we used Mg- and Ni-containing solutions and systematically investigated the Mg and Ni coprecipitates’ phase transformation during sequential/concurrent carbonation and sulfidation. During a single carbonation process, hydromagnesite dehydrated and formed magnesite over time. Nickel bicarbonate formed and became a Mg–Ni carbonate solid solution because of their similar ionic radii. During a single sulfidation process, the pH did not affect Ni-sulfide formation, but it controlled Mg behavior. Specifically, at pH 9.6, brucite formed, while at pH 7.8, Mg<sup>2+</sup> remained in the solution. For the sequential carbonation–sulfidation process, Ni-carbonate formed during carbonation converted to Ni-sulfide because of the low Ni-sulfide <i>K</i><sub>sp</sub>. For the sulfidation–carbonation process, Ni-sulfide remained the same even after carbonation and Mg-carbonate precipitates. For the concurrent carbonation and sulfidation process, Mg-carbonate and Ni-sulfide formed simultaneously. This study develops a scientific foundation of carbonation and sulfidation processes, benefiting coupled CO<sub>2</sub> storage and sulfide-enabled resource recovery.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"6 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143876325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-25DOI: 10.1021/acs.jpcc.5c00805
Nikhil S. Chellam, George C. Schatz
Aluminum nanocrystals offer a promising platform for plasmonic photocatalysis, yet a detailed understanding of their electron dynamics and consequent photocatalytic performance has been challenging due to computational limitations. Here, we employ density functional tight-binding methods (DFTB) to investigate the optical properties and H2 dissociation dynamics of Al nanocrystals with varying sizes and geometries. Our real-time simulations reveal that Al’s free electron nature enables efficient light-matter interactions and rapid electronic thermalization. Cubic and octahedral nanocrystals ranging from 0.5 to 4.5 nm exhibit size-dependent plasmon resonances in the ultraviolet, with distinct spectral features arising from the particle geometry and electronic structure. By simulating H2 dissociation near Al nanocrystals, we demonstrate that hot electrons generated through plasmon excitation can overcome the molecule’s strong chemical bond within tens of femtoseconds. The laser intensity threshold is comparable to previous reports for Ag nanocrystals, although significantly lower than that of Au. Notably, the dipolar plasmon mode demonstrates a higher efficiency for this reaction than the localized interband transition for particles at these sizes. Taken together, this work provides mechanistic insights into plasmon-driven catalysis and showcases DFTB’s capability to study quantum plasmonics at unprecedented length and time scales.
{"title":"Density Functional Tight-Binding Captures Plasmon-Driven H2 Dissociation on Al Nanocrystals","authors":"Nikhil S. Chellam, George C. Schatz","doi":"10.1021/acs.jpcc.5c00805","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c00805","url":null,"abstract":"Aluminum nanocrystals offer a promising platform for plasmonic photocatalysis, yet a detailed understanding of their electron dynamics and consequent photocatalytic performance has been challenging due to computational limitations. Here, we employ density functional tight-binding methods (DFTB) to investigate the optical properties and H<sub>2</sub> dissociation dynamics of Al nanocrystals with varying sizes and geometries. Our real-time simulations reveal that Al’s free electron nature enables efficient light-matter interactions and rapid electronic thermalization. Cubic and octahedral nanocrystals ranging from 0.5 to 4.5 nm exhibit size-dependent plasmon resonances in the ultraviolet, with distinct spectral features arising from the particle geometry and electronic structure. By simulating H<sub>2</sub> dissociation near Al nanocrystals, we demonstrate that hot electrons generated through plasmon excitation can overcome the molecule’s strong chemical bond within tens of femtoseconds. The laser intensity threshold is comparable to previous reports for Ag nanocrystals, although significantly lower than that of Au. Notably, the dipolar plasmon mode demonstrates a higher efficiency for this reaction than the localized interband transition for particles at these sizes. Taken together, this work provides mechanistic insights into plasmon-driven catalysis and showcases DFTB’s capability to study quantum plasmonics at unprecedented length and time scales.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"122 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143872632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-25DOI: 10.1021/acs.jpcc.5c00951
Frederico B. Sousa, Alessandra Ames, Mingzu Liu, Pedro L. Gastelois, Vinícius A. Oliveira, Da Zhou, Matheus J. S. Matos, Helio Chacham, Mauricio Terrones, Marcio D. Teodoro, Leandro M. Malard
Transition metal dichalcogenide (TMD) monolayers present a singular coupling in their spin and valley degrees of freedom. Moreover, by applying an external magnetic field it is possible to break the energy degeneracy between their K and −K valleys. This valley Zeeman effect opens the possibility of controlling and distinguishing the spin and valley characters of charge carriers in TMDs by their optical transition energies, making these materials promising for the next generation of spintronic and photonic devices. However, the free excitons of pristine TMD monolayers present a moderate valley Zeeman splitting of ≈0.23 meV/T. Therefore, alternative excitonic states with higher magnetic responses are mandatory for application purposes. Here, we investigate the magneto-optical properties of ambient exposed WS2 and WSe2 monolayers by circularly polarized magneto-photoluminescence experiments at cryogenic temperatures. A broad lower energy photoluminescence emission related to an ensemble of defects is observed, presenting remarkable valley-related splittings of ≈1.45 meV/T and ≈1.11 meV/T for WS2 and WSe2 monolayers, respectively. In addition, we report a significant spin polarization of charge carriers in the defect midgap states induced by the external magnetic field. We explain this spin-polarized population and enhanced valley-related splitting in terms of imbalanced spin-flip transitions, leading to a magnetic field-dependent distribution of charge carriers in multiple defect levels. This effect, together with the individual Zeeman shiftings of the midgap states, explains the strong magneto-optical responses observed. Our work uncovers the singular potential of manipulating the light emission of ambient exposed TMD monolayers by an external magnetic field.
{"title":"Strong Magneto-Optical Responses of an Ensemble of Defect-Bound Excitons in Ambient Exposed WS2 and WSe2 Monolayers","authors":"Frederico B. Sousa, Alessandra Ames, Mingzu Liu, Pedro L. Gastelois, Vinícius A. Oliveira, Da Zhou, Matheus J. S. Matos, Helio Chacham, Mauricio Terrones, Marcio D. Teodoro, Leandro M. Malard","doi":"10.1021/acs.jpcc.5c00951","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c00951","url":null,"abstract":"Transition metal dichalcogenide (TMD) monolayers present a singular coupling in their spin and valley degrees of freedom. Moreover, by applying an external magnetic field it is possible to break the energy degeneracy between their K and −K valleys. This valley Zeeman effect opens the possibility of controlling and distinguishing the spin and valley characters of charge carriers in TMDs by their optical transition energies, making these materials promising for the next generation of spintronic and photonic devices. However, the free excitons of pristine TMD monolayers present a moderate valley Zeeman splitting of ≈0.23 meV/T. Therefore, alternative excitonic states with higher magnetic responses are mandatory for application purposes. Here, we investigate the magneto-optical properties of ambient exposed WS<sub>2</sub> and WSe<sub>2</sub> monolayers by circularly polarized magneto-photoluminescence experiments at cryogenic temperatures. A broad lower energy photoluminescence emission related to an ensemble of defects is observed, presenting remarkable valley-related splittings of ≈1.45 meV/T and ≈1.11 meV/T for WS<sub>2</sub> and WSe<sub>2</sub> monolayers, respectively. In addition, we report a significant spin polarization of charge carriers in the defect midgap states induced by the external magnetic field. We explain this spin-polarized population and enhanced valley-related splitting in terms of imbalanced spin-flip transitions, leading to a magnetic field-dependent distribution of charge carriers in multiple defect levels. This effect, together with the individual Zeeman shiftings of the midgap states, explains the strong magneto-optical responses observed. Our work uncovers the singular potential of manipulating the light emission of ambient exposed TMD monolayers by an external magnetic field.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"55 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143876327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-24DOI: 10.1021/acs.jpcc.5c01075
Tim H. Reuter, Lkhamsuren Bayarjargal, Daniel Rytz, Sebastian Schwung, Victor Milman, Björn Winkler
We investigated the pressure- and temperature-dependent phase transitions in KTN40 (KTa0.6Nb0.4O3) and KNbO3, two members of the perovskite-type ferroelectric solid solution system KTN (KTaxNb1–xO3), by heat capacity measurements, Raman spectroscopy, and second harmonic generation (SHG). The phase transition temperatures for the rhombohedral → orthorhombic → tetragonal → cubic sequence in KTN40 were determined to be 180(2) K, 225(2) K, and 295(2) K, respectively, by heat capacity measurements. For KNbO3, SHG measurements revealed orthorhombic → tetragonal → cubic transitions at 460(3) K and 720(3) K. In both compounds, SHG experiments indicated the presence of polar nanoregions within the cubic phase above the Curie temperatures of KTN40 and KNbO3. The dynamics and stability fields of these polar nanoregions were analyzed, resulting in Burns temperatures Td of 510(5) K for KTN40 and 1000(5) K for KNbO3. Intermediate temperatures, T*, where polar nanoregions begin to merge into larger domains, were identified for KTN40 and KNbO3 to be 350(5) K and 775(5) K, respectively. The pressure-dependent tetragonal → cubic phase transition was observed at 1.3(1) GPa for KTN40 and 15(0.5) GPa for KNbO3 using SHG. SHG measurements further confirmed polar nanoregions occurring in the cubic phase above the Curie pressures of KTN40 and KNbO3. Burns pressures pd were determined to be 6(1) GPa for KTN40 and 24(1) GPa and intermediate pressures p* were found at 1.8(2) GPa and 17(1) GPa, respectively. The known phase boundaries in temperature- and pressure-dependent phase diagrams could be reproduced and extended and phase diagrams could be enhanced by the addition of stability fields of polar nanoregions. It could also be shown that the dynamics of the polar nanoregions depend on chemical composition, as temperature-induced polar nanoregions in KTN40 appear to be smaller than in KNbO3. In addition, this study contains thermodynamic data for KNbO3, KTN40 and KTaO3. Based on the excess entropy for KTN40, these show that the formation of solid solutions tends to be favored in the KTN system compared to segregation.
{"title":"Pressure- and Temperature-Dependence of Polar Nanoregions in KTN40 (KTa0.6Nb0.4O3) and KNbO3","authors":"Tim H. Reuter, Lkhamsuren Bayarjargal, Daniel Rytz, Sebastian Schwung, Victor Milman, Björn Winkler","doi":"10.1021/acs.jpcc.5c01075","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c01075","url":null,"abstract":"We investigated the pressure- and temperature-dependent phase transitions in KTN<sub>40</sub> (KTa<sub>0.6</sub>Nb<sub>0.4</sub>O<sub>3</sub>) and KNbO<sub>3</sub>, two members of the perovskite-type ferroelectric solid solution system KTN (KTa<sub><i>x</i></sub>Nb<sub>1–<i>x</i></sub>O<sub>3</sub>), by heat capacity measurements, Raman spectroscopy, and second harmonic generation (SHG). The phase transition temperatures for the rhombohedral → orthorhombic → tetragonal → cubic sequence in KTN<sub>40</sub> were determined to be 180(2) K, 225(2) K, and 295(2) K, respectively, by heat capacity measurements. For KNbO<sub>3</sub>, SHG measurements revealed orthorhombic → tetragonal → cubic transitions at 460(3) K and 720(3) K. In both compounds, SHG experiments indicated the presence of polar nanoregions within the cubic phase above the Curie temperatures of KTN<sub>40</sub> and KNbO<sub>3</sub>. The dynamics and stability fields of these polar nanoregions were analyzed, resulting in Burns temperatures <i>T</i><sub>d</sub> of 510(5) K for KTN<sub>40</sub> and 1000(5) K for KNbO<sub>3</sub>. Intermediate temperatures, <i>T</i>*, where polar nanoregions begin to merge into larger domains, were identified for KTN<sub>40</sub> and KNbO<sub>3</sub> to be 350(5) K and 775(5) K, respectively. The pressure-dependent tetragonal → cubic phase transition was observed at 1.3(1) GPa for KTN<sub>40</sub> and 15(0.5) GPa for KNbO<sub>3</sub> using SHG. SHG measurements further confirmed polar nanoregions occurring in the cubic phase above the Curie pressures of KTN<sub>40</sub> and KNbO<sub>3</sub>. Burns pressures <i>p</i><sub>d</sub> were determined to be 6(1) GPa for KTN<sub>40</sub> and 24(1) GPa and intermediate pressures <i>p</i>* were found at 1.8(2) GPa and 17(1) GPa, respectively. The known phase boundaries in temperature- and pressure-dependent phase diagrams could be reproduced and extended and phase diagrams could be enhanced by the addition of stability fields of polar nanoregions. It could also be shown that the dynamics of the polar nanoregions depend on chemical composition, as temperature-induced polar nanoregions in KTN<sub>40</sub> appear to be smaller than in KNbO<sub>3</sub>. In addition, this study contains thermodynamic data for KNbO<sub>3</sub>, KTN<sub>40</sub> and KTaO<sub>3</sub>. Based on the excess entropy for KTN<sub>40</sub>, these show that the formation of solid solutions tends to be favored in the KTN system compared to segregation.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"23 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143872633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-24DOI: 10.1021/acs.jpcc.5c01563
Linjuan Zhang, Jian-Qiang Wang, Scott Oliver, Chao Jing
Published as part of <i>The Journal of Physical Chemistry C</i> special issue “Spectroscopic Techniques for Renewable Energy”. Nowadays, in the face of escalating global energy demands and pressing environmental concerns, the necessity for developing sustainable energy solutions has become extremely urgent. Renewable energy sources, including hydrogen, carbon conversion, rechargeable batteries, and photovoltaics, have emerged as crucial components in achieving efficient energy conversion and storage. (1−5) However, the realization of this vision is hindered by significant scientific and technological challenges, particularly when it comes to understanding the catalytic processes. The lack of clarity on the underlying mechanisms of catalytic reactions significantly limits the advancement of efficiency and cost-effectiveness catalysts, thus impeding future industrial applications. To address these challenges, advanced spectroscopic techniques are essential for providing deep insight into the intricate processes governing energy-related catalysis (10.1021/acs.jpcc.4c05853). (6) This special issue aims to highlight the critical role that sophisticated spectroscopic methods play in investigating the mechanisms of energy conversion and storage. We focus on a range of cutting-edge spectroscopic methods, including Raman spectroscopy, X-ray absorption spectroscopy and X-ray diffraction (XRD), etc. for unraveling the complexities of catalytic processes. Among these techniques, XRD provides valuable information about the crystal structure of materials, essential for understanding the fundamental architecture of catalytic species (10.1021/acs.jpcc.4c05891, 10.1021/acs.jpcc.4c05992). Raman and infrared spectroscopy shed light on molecular vibrations, offering insights into material composition and chemical interactions (10.1021/acs.jpcc.4c03619, 10.1021/acs.jpcc.4c05826, 10.1021/acs.jpcc.4c05670). Leveraging synchrotron light sources, X-ray absorption and emission spectroscopy affords unparalleled resolution in characterizing the fine electronic structure of materials (10.1021/acs.jpcc.4c05526, 10.1021/acs.jpcc.4c00670, 10.1021/acs.jpcc.4c03528). Many other spectroscopic techniques such as UV–vis spectroscopy (10.1021/acs.jpca.4c04902), intensity-modulated photocurrent spectroscopy (10.1021/acs.jpcc.4c04819), mass spectroscopy (10.1021/acs.jpcc.4c03623), and X-ray photoelectron spectroscopy (10.1021/acs.jpcc.4c03480, 10.1021/acs.jpcc.4c03904, 10.1021/acs.jpcc.4c03034) also enable the identification of electronic states and structural properties, crucial for tailoring materials with optimal catalytic properties. It is worth noting that, in the realm of practical applications, the reaction environment and conditions often differ significantly from those present during lab testing. Traditional <i>ex-situ</i> characterization can fall short of accurately representing the real catalytic reaction processes. Hence, the emphasis on <i>in situ</i> and <i>operando</i>
{"title":"Spectroscopic Techniques for Renewable Energy","authors":"Linjuan Zhang, Jian-Qiang Wang, Scott Oliver, Chao Jing","doi":"10.1021/acs.jpcc.5c01563","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c01563","url":null,"abstract":"Published as part of <i>The Journal of Physical Chemistry C</i> special issue “Spectroscopic Techniques for Renewable Energy”. Nowadays, in the face of escalating global energy demands and pressing environmental concerns, the necessity for developing sustainable energy solutions has become extremely urgent. Renewable energy sources, including hydrogen, carbon conversion, rechargeable batteries, and photovoltaics, have emerged as crucial components in achieving efficient energy conversion and storage. (1−5) However, the realization of this vision is hindered by significant scientific and technological challenges, particularly when it comes to understanding the catalytic processes. The lack of clarity on the underlying mechanisms of catalytic reactions significantly limits the advancement of efficiency and cost-effectiveness catalysts, thus impeding future industrial applications. To address these challenges, advanced spectroscopic techniques are essential for providing deep insight into the intricate processes governing energy-related catalysis (10.1021/acs.jpcc.4c05853). (6) This special issue aims to highlight the critical role that sophisticated spectroscopic methods play in investigating the mechanisms of energy conversion and storage. We focus on a range of cutting-edge spectroscopic methods, including Raman spectroscopy, X-ray absorption spectroscopy and X-ray diffraction (XRD), etc. for unraveling the complexities of catalytic processes. Among these techniques, XRD provides valuable information about the crystal structure of materials, essential for understanding the fundamental architecture of catalytic species (10.1021/acs.jpcc.4c05891, 10.1021/acs.jpcc.4c05992). Raman and infrared spectroscopy shed light on molecular vibrations, offering insights into material composition and chemical interactions (10.1021/acs.jpcc.4c03619, 10.1021/acs.jpcc.4c05826, 10.1021/acs.jpcc.4c05670). Leveraging synchrotron light sources, X-ray absorption and emission spectroscopy affords unparalleled resolution in characterizing the fine electronic structure of materials (10.1021/acs.jpcc.4c05526, 10.1021/acs.jpcc.4c00670, 10.1021/acs.jpcc.4c03528). Many other spectroscopic techniques such as UV–vis spectroscopy (10.1021/acs.jpca.4c04902), intensity-modulated photocurrent spectroscopy (10.1021/acs.jpcc.4c04819), mass spectroscopy (10.1021/acs.jpcc.4c03623), and X-ray photoelectron spectroscopy (10.1021/acs.jpcc.4c03480, 10.1021/acs.jpcc.4c03904, 10.1021/acs.jpcc.4c03034) also enable the identification of electronic states and structural properties, crucial for tailoring materials with optimal catalytic properties. It is worth noting that, in the realm of practical applications, the reaction environment and conditions often differ significantly from those present during lab testing. Traditional <i>ex-situ</i> characterization can fall short of accurately representing the real catalytic reaction processes. Hence, the emphasis on <i>in situ</i> and <i>operando</i> ","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"17 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143867151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-24DOI: 10.1021/acs.jpcc.5c00641
Madeleine K. Wilsey, Teona Taseska, Lydia R. Schultz, Elena Perez, Astrid M. Müller
We present a novel methodology for fabricating surfactant-free mixed-metal nanocatalyst–carbon fiber paper composites, demonstrating significant improvements in impedance, electrocatalytic activity, and long-term stability over laser synthesized drop cast analogues on carbon fiber paper or highly ordered pyrolytic graphite. Our innovative pulsed laser grafting technique is a versatile, one-step aqueous process that integrates nanoparticle generation with surface attachment on macroscopic solid supports, such as sheets, rather than being limited to powders, particulate supports, or organic solvents as in prior methods. It effectively addresses longstanding challenges with nanoparticle adhesion and electrical contact between nanoparticles and macroscopic electrodes, and it alleviates environmental concerns associated with organic solvents. Laser grafting eliminates laborious synthesis, separation, purification, and postsynthesis attachment steps, thus significantly reducing composite preparation time. We fabricated [NiFe]-(OH)2–hydrophilic carbon fiber paper composites using aqueous nickel–iron nitrate solution. Low-fluence 532 nm nanosecond laser pulses minimized surface damage and facilitated effective metal ion excitation for nanoparticle assembly. SEM, EDX and XPS data revealed surface [NiFe]-(OH)2 without carbon encapsulation and prominent Ni–C interactions. The pulsed laser grafted composites showed enhanced electrocatalytic performance for alkaline water oxidation and decreased material charge transfer resistance, compared to drop cast analogues, leading to improved electrical conductivity and mass activity. Additionally, they demonstrated exceptional long-term stability, overcoming common adhesion issues in conventional nanoparticle–support systems, marking a significant advancement in the manufacturing of multimetallic nanoparticle–support composites, with promising implications for electrochemistry and electrocatalysis technologies.
{"title":"Fabrication of Surfactant-Free Mixed-Metal Nanocatalyst–Carbon Fiber Paper Composites via Pulsed Laser Grafting","authors":"Madeleine K. Wilsey, Teona Taseska, Lydia R. Schultz, Elena Perez, Astrid M. Müller","doi":"10.1021/acs.jpcc.5c00641","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c00641","url":null,"abstract":"We present a novel methodology for fabricating surfactant-free mixed-metal nanocatalyst–carbon fiber paper composites, demonstrating significant improvements in impedance, electrocatalytic activity, and long-term stability over laser synthesized drop cast analogues on carbon fiber paper or highly ordered pyrolytic graphite. Our innovative pulsed laser grafting technique is a versatile, one-step aqueous process that integrates nanoparticle generation with surface attachment on macroscopic solid supports, such as sheets, rather than being limited to powders, particulate supports, or organic solvents as in prior methods. It effectively addresses longstanding challenges with nanoparticle adhesion and electrical contact between nanoparticles and macroscopic electrodes, and it alleviates environmental concerns associated with organic solvents. Laser grafting eliminates laborious synthesis, separation, purification, and postsynthesis attachment steps, thus significantly reducing composite preparation time. We fabricated [NiFe]-(OH)<sub>2</sub>–hydrophilic carbon fiber paper composites using aqueous nickel–iron nitrate solution. Low-fluence 532 nm nanosecond laser pulses minimized surface damage and facilitated effective metal ion excitation for nanoparticle assembly. SEM, EDX and XPS data revealed surface [NiFe]-(OH)<sub>2</sub> without carbon encapsulation and prominent Ni–C interactions. The pulsed laser grafted composites showed enhanced electrocatalytic performance for alkaline water oxidation and decreased material charge transfer resistance, compared to drop cast analogues, leading to improved electrical conductivity and mass activity. Additionally, they demonstrated exceptional long-term stability, overcoming common adhesion issues in conventional nanoparticle–support systems, marking a significant advancement in the manufacturing of multimetallic nanoparticle–support composites, with promising implications for electrochemistry and electrocatalysis technologies.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"10 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143867143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-24DOI: 10.1021/acs.jpcc.5c00272
Jette K. Mathiesen, Jie Zhu, Weiming Wan, Shamil Shaikhutdinov, Beatriz Roldan Cuenya
Indium oxide (In2O3) has recently received considerable attention in the catalysis community due to its unexpectedly high selectivity in the hydrogenation of CO2 to methanol. Metal deposition onto In2O3 substantially promotes the activity, while the selectivity remains close to that of bare In2O3, independent of the metal used. To get insight into the metal/In2O3 interaction and the role of the metal/oxide interface in the CO2 hydrogenation reaction, we carried out a near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) study of “inverse” model catalysts prepared by In(III) oxide deposition onto a Ru(0001) substrate. Bulk-like In2O3(111) islands grow on the Ru(0001) surface at the onset of the deposition, and a continuous film is obtained above 5–7 nm of the nominal thickness. NAP-XPS measurements of the In2O3(111) films of various film thickness revealed the formation of metallic In(0) species at 200–280 °C in pure H2 and CO2 + H2 atmospheres if In2O3 partially covers the Ru surface but not on the continuous films. Moreover, these species formed in the H2 containing ambient are altered considerably in the post-reaction samples, highlighting the necessity of operando studies on In2O3-based catalysts. Obviously, the In(0) formation is assisted by facile H2 dissociation on the Ru surface, with H adatoms reacting at the interface to In2O3. XPS results obtained for reference systems prepared by direct In deposition showed that metallic In(0) formed in the H2 atmosphere remains at the In2O3/Ru interface and does not migrate onto Ru to form a surface alloy.
{"title":"Metal–Support Interaction in In2O3-Based Catalysts of CO2 Hydrogenation Studied Using “Inverse” In2O3(111)/Ru(0001) Model Systems","authors":"Jette K. Mathiesen, Jie Zhu, Weiming Wan, Shamil Shaikhutdinov, Beatriz Roldan Cuenya","doi":"10.1021/acs.jpcc.5c00272","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c00272","url":null,"abstract":"Indium oxide (In<sub>2</sub>O<sub>3</sub>) has recently received considerable attention in the catalysis community due to its unexpectedly high selectivity in the hydrogenation of CO<sub>2</sub> to methanol. Metal deposition onto In<sub>2</sub>O<sub>3</sub> substantially promotes the activity, while the selectivity remains close to that of bare In<sub>2</sub>O<sub>3</sub>, independent of the metal used. To get insight into the metal/In<sub>2</sub>O<sub>3</sub> interaction and the role of the metal/oxide interface in the CO<sub>2</sub> hydrogenation reaction, we carried out a near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) study of “inverse” model catalysts prepared by In(III) oxide deposition onto a Ru(0001) substrate. Bulk-like In<sub>2</sub>O<sub>3</sub>(111) islands grow on the Ru(0001) surface at the onset of the deposition, and a continuous film is obtained above 5–7 nm of the nominal thickness. NAP-XPS measurements of the In<sub>2</sub>O<sub>3</sub>(111) films of various film thickness revealed the formation of metallic In(0) species at 200–280 °C in pure H<sub>2</sub> and CO<sub>2</sub> + H<sub>2</sub> atmospheres if In<sub>2</sub>O<sub>3</sub> partially covers the Ru surface but not on the continuous films. Moreover, these species formed in the H<sub>2</sub> containing ambient are altered considerably in the post-reaction samples, highlighting the necessity of operando studies on In<sub>2</sub>O<sub>3</sub>-based catalysts. Obviously, the In(0) formation is assisted by facile H<sub>2</sub> dissociation on the Ru surface, with H adatoms reacting at the interface to In<sub>2</sub>O<sub>3</sub>. XPS results obtained for reference systems prepared by direct In deposition showed that metallic In(0) formed in the H<sub>2</sub> atmosphere remains at the In<sub>2</sub>O<sub>3</sub>/Ru interface and does not migrate onto Ru to form a surface alloy.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"13 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143867104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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