Pub Date : 2026-02-09DOI: 10.1021/acs.jpcc.5c06383
Weihua Wu,Robbert W. E. van de Kruijs,Dirk J. Gravesteijn,Z. Silvester Houweling,Giorgio Colombi,Alexey Y. Kovalgin
In this work, we develop and validate a spectroscopic ellipsometry (SE) approach to first monitor the performance of a thin-film palladium/hafnium (Pd/Hf) hydrogen detection sensor suitable for applications up to a temperature of 450 °C and second to quantify the hydrogen permeation through thin capping layers. A 2.5 nm aluminum oxide (Al2O3) thin film is tested as a potential protective hydrogen barrier under hydrogen radical (H*) flux conditions found in extreme ultraviolet lithography scanners. To this end, the interaction between molecular and atomic hydrogen and a Pd/Hf stack was studied at temperatures from 120 to 670 °C. Optical and structural changes during hydrogen exposures were investigated using in situ SE and ex situ X-ray diffraction. The stack is confirmed to remain stable in the respective metallic phases during vacuum annealing up to 450 °C without forming any crystalline HfO2 by reaction with trace oxidative species. Upon molecular H2 exposure, the formation of hafnium hydride (HfHx) can be observed for temperatures up to 350 °C, while Hf oxidation occurs at higher temperatures. Upon exposure to H*, HfHx formation is observed for temperatures up to 450 °C, again followed by oxidation at higher temperatures. Capping the stack with a 2.5 nm Al2O3 layer fabricated by atomic layer deposition led to a retardation of 70 times for hydrogenation upon H* exposure at 450 °C accompanied by little oxidation. An analytical SE model was developed for analyzing the H-content incorporated into this stack through the Al2O3 capping layer, showing a decent match with that from absolute quantification by elastic recoil detection analysis.
{"title":"Sensing of Hydrogen Diffusion through Protective Caps: An Ellipsometric Approach to Estimate Hydrogen Content in Pd/Hf Stacks with an Al2O3 Cap","authors":"Weihua Wu,Robbert W. E. van de Kruijs,Dirk J. Gravesteijn,Z. Silvester Houweling,Giorgio Colombi,Alexey Y. Kovalgin","doi":"10.1021/acs.jpcc.5c06383","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c06383","url":null,"abstract":"In this work, we develop and validate a spectroscopic ellipsometry (SE) approach to first monitor the performance of a thin-film palladium/hafnium (Pd/Hf) hydrogen detection sensor suitable for applications up to a temperature of 450 °C and second to quantify the hydrogen permeation through thin capping layers. A 2.5 nm aluminum oxide (Al2O3) thin film is tested as a potential protective hydrogen barrier under hydrogen radical (H*) flux conditions found in extreme ultraviolet lithography scanners. To this end, the interaction between molecular and atomic hydrogen and a Pd/Hf stack was studied at temperatures from 120 to 670 °C. Optical and structural changes during hydrogen exposures were investigated using in situ SE and ex situ X-ray diffraction. The stack is confirmed to remain stable in the respective metallic phases during vacuum annealing up to 450 °C without forming any crystalline HfO2 by reaction with trace oxidative species. Upon molecular H2 exposure, the formation of hafnium hydride (HfHx) can be observed for temperatures up to 350 °C, while Hf oxidation occurs at higher temperatures. Upon exposure to H*, HfHx formation is observed for temperatures up to 450 °C, again followed by oxidation at higher temperatures. Capping the stack with a 2.5 nm Al2O3 layer fabricated by atomic layer deposition led to a retardation of 70 times for hydrogenation upon H* exposure at 450 °C accompanied by little oxidation. An analytical SE model was developed for analyzing the H-content incorporated into this stack through the Al2O3 capping layer, showing a decent match with that from absolute quantification by elastic recoil detection analysis.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"241 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2026-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146138799","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 : 2026-02-08DOI: 10.1021/acs.jpcc.5c05791
Florentino López-Urías,Francisco Sánchez-Ochoa
We investigated the honeycomb lattice using a two-orbital (α and β) Hubbard model and many-body exact calculations. The spin gap (Δs), charge gap (Δc), intrasite (γiiαβ=⟨S→iα·S→iβ⟩), intersite (γijαβ=⟨S→iα·S→jβ⟩), spin–spin correlations, and orbital magnetic moments μiα are analyzed for different band-filling (n), which denotes the number of electrons per site. Special attention was set in one-quarter-filled (n = 1) and half-filled (n = 2) bands. The results are presented by varying Coulomb repulsion (U), Hund’s coupling (JH), external magnetic field (B), and orbital energy splitting (Δϵ). For the one-quarter-filled band, an intrasite magnetic disorder (γiiαβ≈0) begins to form for large values of U/t, which is interpreted as a possible signature of a resonating valence bond state. Full orbital polarization (γiiαβ=0.25) with intersite antiferromagnetic (AFM) order (γijαβ=−0.25) was observed in the half-filled band for U/t ≫ 1, indicating that the two-orbital Hubbard model can be mapped to an AFM Heisenberg model with S = 1. The increase of JH is conductive to insulating and metallic phases for half- and one-quarter-filled bands, respectively. For a fractional n, the honeycomb lattice can exhibit spin-glass-like behavior, predominating as a disordered magnetic system characterized by random values of γijαβ. The magnetic field induced a reduction in Δc, which became zero at the critical external magnetic field. Twisted bilayer graphene (TBG) exhibits approximately flat electronic bands at magic angles and interesting correlated phenomena, such as unconventional superconductivity and correlated insulating states around n = 1 and n = 2, respectively. The dominance of electron–electron interactions in TBG makes the Hubbard model, in various versions (extended or multi-orbital), offer a practical, structure-scale account for investigating many-body effects in large moiré unit cells, where first-principles density-functional theory calculations are computationally challenging.
{"title":"Electron Correlations Study toward Understanding Twisted Bilayer Graphene: Two-Orbital Hubbard Model and Exact Numerical Calculations","authors":"Florentino López-Urías,Francisco Sánchez-Ochoa","doi":"10.1021/acs.jpcc.5c05791","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c05791","url":null,"abstract":"We investigated the honeycomb lattice using a two-orbital (α and β) Hubbard model and many-body exact calculations. The spin gap (Δs), charge gap (Δc), intrasite (γiiαβ=⟨S→iα·S→iβ⟩), intersite (γijαβ=⟨S→iα·S→jβ⟩), spin–spin correlations, and orbital magnetic moments μiα are analyzed for different band-filling (n), which denotes the number of electrons per site. Special attention was set in one-quarter-filled (n = 1) and half-filled (n = 2) bands. The results are presented by varying Coulomb repulsion (U), Hund’s coupling (JH), external magnetic field (B), and orbital energy splitting (Δϵ). For the one-quarter-filled band, an intrasite magnetic disorder (γiiαβ≈0) begins to form for large values of U/t, which is interpreted as a possible signature of a resonating valence bond state. Full orbital polarization (γiiαβ=0.25) with intersite antiferromagnetic (AFM) order (γijαβ=−0.25) was observed in the half-filled band for U/t ≫ 1, indicating that the two-orbital Hubbard model can be mapped to an AFM Heisenberg model with S = 1. The increase of JH is conductive to insulating and metallic phases for half- and one-quarter-filled bands, respectively. For a fractional n, the honeycomb lattice can exhibit spin-glass-like behavior, predominating as a disordered magnetic system characterized by random values of γijαβ. The magnetic field induced a reduction in Δc, which became zero at the critical external magnetic field. Twisted bilayer graphene (TBG) exhibits approximately flat electronic bands at magic angles and interesting correlated phenomena, such as unconventional superconductivity and correlated insulating states around n = 1 and n = 2, respectively. The dominance of electron–electron interactions in TBG makes the Hubbard model, in various versions (extended or multi-orbital), offer a practical, structure-scale account for investigating many-body effects in large moiré unit cells, where first-principles density-functional theory calculations are computationally challenging.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"244 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2026-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146138855","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 : 2026-02-08DOI: 10.1021/acs.jpcc.5c08226
Bin Feng,Haochen Sun,Yilin Zhao,Wei Wang,Yiming Zhao,Aimin Ge
The formation of the solid-electrolyte interphase (SEI) plays a critical role in the electrochemical performance and cycling stability of organic anode materials in lithium-ion batteries. In this study, we employ operando attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy to investigate the real-time dynamics of SEI formation on polyimide-based organic anodes during charging–discharging cycles. By comparing two commonly used carbonate-based and ether-based electrolytes, we reveal distinct differences in the composition and characteristics of the SEI. These distinct SEI characteristics lead to markedly different electrochemical performances. In ether-based electrolytes, the SEI is predominantly inorganic, facilitating efficient ion transport. The rapid capacity fade is predominated by the irreversible lithium-ion insertion reactions of aromatic ring structures. On the other hand, in carbonate-based electrolytes, the SEI is rich in organic components, leading to higher impedance. In this case, both irreversible carbonyl enolization and lithium-ion insertion into aromatic rings contribute to the rapid capacity fade.
{"title":"The Influence of the Solid-Electrolyte Interphase on Polyimide Anodes Probed by Operando Infrared Spectroscopy","authors":"Bin Feng,Haochen Sun,Yilin Zhao,Wei Wang,Yiming Zhao,Aimin Ge","doi":"10.1021/acs.jpcc.5c08226","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c08226","url":null,"abstract":"The formation of the solid-electrolyte interphase (SEI) plays a critical role in the electrochemical performance and cycling stability of organic anode materials in lithium-ion batteries. In this study, we employ operando attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy to investigate the real-time dynamics of SEI formation on polyimide-based organic anodes during charging–discharging cycles. By comparing two commonly used carbonate-based and ether-based electrolytes, we reveal distinct differences in the composition and characteristics of the SEI. These distinct SEI characteristics lead to markedly different electrochemical performances. In ether-based electrolytes, the SEI is predominantly inorganic, facilitating efficient ion transport. The rapid capacity fade is predominated by the irreversible lithium-ion insertion reactions of aromatic ring structures. On the other hand, in carbonate-based electrolytes, the SEI is rich in organic components, leading to higher impedance. In this case, both irreversible carbonyl enolization and lithium-ion insertion into aromatic rings contribute to the rapid capacity fade.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"23 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2026-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146138856","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}
The energy release rate of ammonium perchlorate (AP) is crucial for the detonation performance of both composite explosives and propellant systems. This work systematically investigates how 15N-substitution influences the structure, thermal decomposition, and microdetonation properties of AP. Structural analyses reveal that while 15N-substitution preserves the crystal packing model, it induces a slight elongation of the 15N–H bonds and a marginal increase in crystal density. Thermal analysis shows that the fundamental decomposition pathway remains unchanged; however, the apparent activation energy is significantly reduced from 68.15 kJ/mol (raw AP) to 45.52 kJ/mol for 15N-AP. This reduction demonstrates a pronounced reverse kinetic isotope effect (KIE) on proton transfer between NH4+ and ClO4–, which accelerates low-temperature decomposition. Laser-driven shock wave tests further confirm that 15N-AP exhibits a higher initial shock wave velocity and enhanced energy release intensity. Collectively, these findings highlight 15N-substitution as a novel and effective strategy for modulating energy release, offering a promising approach to amplify the performance of energetic formulations via isotopic substitution engineering.
{"title":"Reverse 15N Kinetic Isotope Effect Amplifies the Energy Release of Ammonium Perchlorate","authors":"Yilin Cao, Wei Wang, Ziping Yin, Zhe Zhai, Guanchen Shen, Jiaxin Wu, Wen Lei, Pan Chen, Zhaocong Shang, Zihui Meng, Chuan Xiao","doi":"10.1021/acs.jpcc.5c08282","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c08282","url":null,"abstract":"The energy release rate of ammonium perchlorate (AP) is crucial for the detonation performance of both composite explosives and propellant systems. This work systematically investigates how <sup>15</sup>N-substitution influences the structure, thermal decomposition, and microdetonation properties of AP. Structural analyses reveal that while <sup>15</sup>N-substitution preserves the crystal packing model, it induces a slight elongation of the <sup>15</sup>N–H bonds and a marginal increase in crystal density. Thermal analysis shows that the fundamental decomposition pathway remains unchanged; however, the apparent activation energy is significantly reduced from 68.15 kJ/mol (raw AP) to 45.52 kJ/mol for <sup>15</sup>N-AP. This reduction demonstrates a pronounced reverse kinetic isotope effect (KIE) on proton transfer between NH<sub>4</sub><sup>+</sup> and ClO<sub>4</sub><sup>–</sup>, which accelerates low-temperature decomposition. Laser-driven shock wave tests further confirm that <sup>15</sup>N-AP exhibits a higher initial shock wave velocity and enhanced energy release intensity. Collectively, these findings highlight <sup>15</sup>N-substitution as a novel and effective strategy for modulating energy release, offering a promising approach to amplify the performance of energetic formulations via isotopic substitution engineering.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"241 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2026-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146135313","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 : 2026-02-06DOI: 10.1021/acs.jpcc.5c07119
Pablo Bastante, Ross J. Davidson, Yahia Chelli, Abdalghani H. S. Daaoub, Pilar Cea, Santiago Martin, Andrei S. Batsanov, Sara Sangtarash, Hatef Sadeghi, Martin R. Bryce, Nicolas Agrait
The present work provides insight into the effect of connectivity within isomeric 3,5-bis(pyridin-2-yl)phenyl (N^C^N) platinum and palladium complexes on their electron transmission properties within gold|molecule|gold junctions. The ligands 3,5-bis(4-(methylthio)pyridin-2-yl)phenyl hexanoate (LmH) and 3,5-bis(5-(methylthio)pyridin-2-yl)phenyl hexanoate (LpH) were synthesized and coordinated with either PtCl or PdCl to form complexes Ptm, Ptp, Pdm and Pdp. X-ray photoelectron spectroscopy (XPS) measurements evaluated the contacting modes of the molecules in the junctions. A combination of scanning tunneling microscopy-break junction (STM-BJ) measurements and density functional theory (DFT) calculations demonstrate that for the single-molecule S···S contacted junctions metal coordination enhanced the conductance compared with the free ligands. Notably, the higher degree of orbital mixing between the metal center and the ligand π-orbitals in the metal complexes plays a greater role than quantum interference to the extent that the complexes that incorporate ligands substituted with thiomethyl groups in meta positions relative to the pyridine-benzene linkages have a higher conductance than their para-analogs, e.g., Ptp −3.8 log(G/G0) and Ptm −3.3 log(G/G0), in contrast to the usual conductance trend (para > meta) for purely organic π-electron systems.
{"title":"Experimental and Theoretical Studies of Isomeric Metal (N^C^N)Cl Coordination Complexes (Metal = Pt, Pd) with Multiple Conductance Pathways in Single-Molecule Junctions","authors":"Pablo Bastante, Ross J. Davidson, Yahia Chelli, Abdalghani H. S. Daaoub, Pilar Cea, Santiago Martin, Andrei S. Batsanov, Sara Sangtarash, Hatef Sadeghi, Martin R. Bryce, Nicolas Agrait","doi":"10.1021/acs.jpcc.5c07119","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c07119","url":null,"abstract":"The present work provides insight into the effect of connectivity within isomeric 3,5-bis(pyridin-2-yl)phenyl (N^C^N) platinum and palladium complexes on their electron transmission properties within gold|molecule|gold junctions. The ligands 3,5-bis(4-(methylthio)pyridin-2-yl)phenyl hexanoate (<b>L</b><sup><b>m</b></sup>H) and 3,5-bis(5-(methylthio)pyridin-2-yl)phenyl hexanoate (<b>L</b><sup><b>p</b></sup>H) were synthesized and coordinated with either PtCl or PdCl to form complexes <b>Pt</b><sup><b>m</b></sup>, <b>Pt</b><sup><b>p</b></sup>, <b>Pd</b><sup><b>m</b></sup> and <b>Pd</b><sup><b>p</b></sup>. X-ray photoelectron spectroscopy (XPS) measurements evaluated the contacting modes of the molecules in the junctions. A combination of scanning tunneling microscopy-break junction (STM-BJ) measurements and density functional theory (DFT) calculations demonstrate that for the single-molecule S···S contacted junctions metal coordination enhanced the conductance compared with the free ligands. Notably, the higher degree of orbital mixing between the metal center and the ligand π-orbitals in the metal complexes plays a greater role than quantum interference to the extent that the complexes that incorporate ligands substituted with thiomethyl groups in <i>meta</i> positions relative to the pyridine-benzene linkages have a higher conductance than their <i>para</i>-analogs, e.g., <b>Pt</b><sup><b>p</b></sup> −3.8 log(<i>G</i>/<i>G</i><sub>0</sub>) and <b>Pt</b><sup><b>m</b></sup> −3.3 log(<i>G</i>/<i>G</i><sub>0</sub>), in contrast to the usual conductance trend (<i>para</i> > <i>meta</i>) for purely organic π-electron systems.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"177 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146122389","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 : 2026-02-06DOI: 10.1021/acs.jpcc.5c07042
Ga-Un Jeong, Ryan Morelock, Soumendu Bagchi, Nadire Nayir, Adri C.T. van Duin, Panchapakesan Ganesh
Bismuth selenide (Bi2Se3) is a widely studied topological insulator and thermoelectric material whose properties are highly sensitive to crystal quality, defects, and stoichiometry. Recrystallization is an effective method of improving the crystal quality of materials, yet traditional experimental approaches are time-consuming and resource-intensive and often rely on trial and error. This work presents a new Bi/Se ReaxFF force field with the ability to recrystallize bulk Bi2Se3 into van der Waals (vdW)-layered phases under various thermal and kinetic conditions. The force field is parameterized using a diverse quantum mechanical data set, which includes formation energies of bulk layered and nonlayered Bi–Se phases, the energy–volume equation of state, point defect formation energies, the composition-dependent energetic stability trends of high-temperature BixSey clusters, and amorphous Bi2Se3 structures sampled from melt-quench molecular dynamics simulations. Our simulations reveal that structural characteristics of the resulting recrystallized vdW materials, such as stacking order and stoichiometry, depend on melt-quenching processing parameters such as the cooling rate and annealing temperature. This novel force field constitutes a predictive framework for the structural tuning of complex Bi–Se vdW materials through recrystallization conditions, laying a foundation for computational design of a much wider selection of chalcogenides.
{"title":"Development of a ReaxFF Reactive Force Field for the Crystallization of van der Waals-Layered Bismuth Selenide","authors":"Ga-Un Jeong, Ryan Morelock, Soumendu Bagchi, Nadire Nayir, Adri C.T. van Duin, Panchapakesan Ganesh","doi":"10.1021/acs.jpcc.5c07042","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c07042","url":null,"abstract":"Bismuth selenide (Bi<sub>2</sub>Se<sub>3</sub>) is a widely studied topological insulator and thermoelectric material whose properties are highly sensitive to crystal quality, defects, and stoichiometry. Recrystallization is an effective method of improving the crystal quality of materials, yet traditional experimental approaches are time-consuming and resource-intensive and often rely on trial and error. This work presents a new Bi/Se ReaxFF force field with the ability to recrystallize bulk Bi<sub>2</sub>Se<sub>3</sub> into van der Waals (vdW)-layered phases under various thermal and kinetic conditions. The force field is parameterized using a diverse quantum mechanical data set, which includes formation energies of bulk layered and nonlayered Bi–Se phases, the energy–volume equation of state, point defect formation energies, the composition-dependent energetic stability trends of high-temperature Bi<sub><i>x</i></sub>Se<sub><i>y</i></sub> clusters, and amorphous Bi<sub>2</sub>Se<sub>3</sub> structures sampled from melt-quench molecular dynamics simulations. Our simulations reveal that structural characteristics of the resulting recrystallized vdW materials, such as stacking order and stoichiometry, depend on melt-quenching processing parameters such as the cooling rate and annealing temperature. This novel force field constitutes a predictive framework for the structural tuning of complex Bi–Se vdW materials through recrystallization conditions, laying a foundation for computational design of a much wider selection of chalcogenides.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"311 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146135328","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}
MXene quantum dots (QDs) have emerged as a promising class of zero-dimensional nanomaterials, attracting growing attention due to their remarkable physicochemical properties. Niobium carbide QDs (Nb2C QDs), derived from two-dimensional (2D) Nb2CTx, is a rising material with great potential in optical applications. Herein, nitrogen-doped Nb2C QDs (N–Nb2C QDs) were synthesized via sonication-assisted hydrothermal treatment. The obtained N–Nb2C QDs exhibit blue fluorescence with excitation-dependent emission. We developed a fluorescent sensor enabling N–Nb2C QDs for visual and quantitative detection of tetracycline (TC) antibiotics. The blue fluorescence of N–Nb2C QDs can be quenched by TC through static quenching and inner filter effect (IFE). The synergistic effect of both static quenching and IFE caused by TC makes the developed fluorescence sensor have a linear range for TC from 0.25 to 6.50 μM with a detection limit of 30.2 nM and a significant fluorescence color change from blue to cyan-green. Due to the simplicity and recognizable color change, a machine learning based approach was employed to determine the TC concentration from a visual fluorescence image. A convolutional neural network (CNN) architecture was used for the regression analysis. The model shows a strong predictive performance, achieving a coefficient of determination (R2) of 0.966, which reflects a high level of accuracy in estimating the TC concentrations.
{"title":"Smart Visual Fluorescence Sensing of Tetracycline Using N-Doped Nb2C Quantum Dots and CNN-Based Regression Quantification","authors":"Bhasha Sathyan, Vishnu Harikumar, Gaurav Banerjee, Jobin Cyriac","doi":"10.1021/acs.jpcc.5c06964","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c06964","url":null,"abstract":"MXene quantum dots (QDs) have emerged as a promising class of zero-dimensional nanomaterials, attracting growing attention due to their remarkable physicochemical properties. Niobium carbide QDs (Nb<sub>2</sub>C QDs), derived from two-dimensional (2D) Nb<sub>2</sub>CT<sub><i>x</i></sub>, is a rising material with great potential in optical applications. Herein, nitrogen-doped Nb<sub>2</sub>C QDs (N–Nb<sub>2</sub>C QDs) were synthesized via sonication-assisted hydrothermal treatment. The obtained N–Nb<sub>2</sub>C QDs exhibit blue fluorescence with excitation-dependent emission. We developed a fluorescent sensor enabling N–Nb<sub>2</sub>C QDs for visual and quantitative detection of tetracycline (TC) antibiotics. The blue fluorescence of N–Nb<sub>2</sub>C QDs can be quenched by TC through static quenching and inner filter effect (IFE). The synergistic effect of both static quenching and IFE caused by TC makes the developed fluorescence sensor have a linear range for TC from 0.25 to 6.50 μM with a detection limit of 30.2 nM and a significant fluorescence color change from blue to cyan-green. Due to the simplicity and recognizable color change, a machine learning based approach was employed to determine the TC concentration from a visual fluorescence image. A convolutional neural network (CNN) architecture was used for the regression analysis. The model shows a strong predictive performance, achieving a coefficient of determination (R<sup>2</sup>) of 0.966, which reflects a high level of accuracy in estimating the TC concentrations.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"47 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146122394","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 : 2026-02-06DOI: 10.1021/acs.jpcc.5c07897
Kexin Cheng, Weitao Su, Xumin Chen, Fei Chen, Yijie Zeng, Hong-Wei Lu
Laser ablation and irradiation have long been established as efficient methods to prepare atomic-scale thickness two-dimensional (2D) electronic devices based on transition metal dichalcogenides (TMDs). However, comprehending the spatially nonuniform material transition of TMD thin layers intrinsically induced by the nonuniform heating of a tightly focused laser beam requires an analytical tool with nanoscale spatial resolution. Herein, tip-enhanced photoluminescence (TEPL), achieving a remarkable spatial resolution of 19 nm, was utilized to image the laser-irradiated monolayer (1L) MoS2 to meet these requirements. TEPL imaging reveals that with an optimized laser power density of 2.51 × 109 mW/cm2 and a short dwell time of 17 s, p-doping and enhanced A exciton photoluminescence (PL) intensity emerge at the laser focus center. Conversely, prolonged dwell time exceeding 20 s induces irreversible A exciton PL intensity reduction owing to the oxidation at the focal center and simultaneously causes PL enhancement at the peripheral region surrounding it. These TEPL results indicate that the far-field laser irradiation-induced temporal PL spectral variation of MoS2 arises from the local competition between the p-type doping-induced PL enhancement and the oxidation-induced PL quenching. By optimizing the laser power and dwell time, a large area and high quality p–n junction can be fabricated on 1L MoS2 flake via pixel-by-pixel scan. By integrating the TEPL results with the far-field temporal PL spectral variation, our findings give new insights into interpreting the laser irradiation process of MoS2 at the nanoscale and would be helpful for developing novel TMD-based optoelectronic devices.
{"title":"Investigating the Laser Irradiation of Monolayer MoS2 Using Tip-Enhanced Photoluminescence at the Nanoscale","authors":"Kexin Cheng, Weitao Su, Xumin Chen, Fei Chen, Yijie Zeng, Hong-Wei Lu","doi":"10.1021/acs.jpcc.5c07897","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c07897","url":null,"abstract":"Laser ablation and irradiation have long been established as efficient methods to prepare atomic-scale thickness two-dimensional (2D) electronic devices based on transition metal dichalcogenides (TMDs). However, comprehending the spatially nonuniform material transition of TMD thin layers intrinsically induced by the nonuniform heating of a tightly focused laser beam requires an analytical tool with nanoscale spatial resolution. Herein, tip-enhanced photoluminescence (TEPL), achieving a remarkable spatial resolution of 19 nm, was utilized to image the laser-irradiated monolayer (1L) MoS<sub>2</sub> to meet these requirements. TEPL imaging reveals that with an optimized laser power density of 2.51 × 10<sup>9</sup> mW/cm<sup>2</sup> and a short dwell time of 17 s, p-doping and enhanced <i>A</i> exciton photoluminescence (PL) intensity emerge at the laser focus center. Conversely, prolonged dwell time exceeding 20 s induces irreversible <i>A</i> exciton PL intensity reduction owing to the oxidation at the focal center and simultaneously causes PL enhancement at the peripheral region surrounding it. These TEPL results indicate that the far-field laser irradiation-induced temporal PL spectral variation of MoS<sub>2</sub> arises from the local competition between the p-type doping-induced PL enhancement and the oxidation-induced PL quenching. By optimizing the laser power and dwell time, a large area and high quality p–n junction can be fabricated on 1L MoS<sub>2</sub> flake via pixel-by-pixel scan. By integrating the TEPL results with the far-field temporal PL spectral variation, our findings give new insights into interpreting the laser irradiation process of MoS<sub>2</sub> at the nanoscale and would be helpful for developing novel TMD-based optoelectronic devices.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"68 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146122431","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}
Unsymmetrical dimethylhydrazine (UDMH), a carcinogenic aerospace propellant, poses severe environmental threats due to its persistence and high toxicity. Despite the proven efficacy of electrocatalytic technology in degrading diverse organic contaminants, the development of electrocatalysts with high stability, activity, and selectivity for efficient UDMH degradation remains a critical and persistent challenge. Crucially, identifying promising candidates among the vast design space of potential catalysts is resource-intensive and time-consuming, and the process involves conventional experimental approaches. To overcome this bottleneck and accelerate discovery, we systematically investigate the potential of single transition metal (TM) atoms anchored on graphitic carbon nitride (g-C3N4) monolayers─serving as TM-g-C3N4 SACs─for UDMH degradation via first-principles high-throughput screening. This powerful computational approach enables the comprehensive evaluation of stability, adsorption behavior, and catalytic activity across 28 TM-g-C3N4 candidates in a systematic and efficient manner. Remarkably, Os-g-C3N4 emerges as the premier candidate, demonstrating robust UDMH capture via dual-terminal adsorption coupled with an ultralow dehydrogenation barrier (0.2702 eV, amino terminal) that is 59% lower than Pt-based systems. Crucially, this high activity coexists with exceptional stability (binding energy: −7.52 eV; dissolution potential: 0.84 V) and 41% cost reduction (90 vs 220 RMB/g). Mechanistic analysis reveals that metallic band formation post-Os loading and empty-orbital-mediated electron transfer synergistically activate UDMH, while orbital hybridization accelerates charge transfer. This work not only establishes Os-g-C3N4 as a sustainable solution for rocket fuel remediation but also provides a universal SAC design blueprint transferable to diverse pollutant degradation systems.
不对称二甲肼（UDMH）是一种致癌的航天推进剂，其持久性和高毒性对环境构成严重威胁。尽管电催化技术在降解多种有机污染物方面已被证明是有效的，但开发具有高稳定性、高活性和高选择性的电催化剂来高效降解UDMH仍然是一个关键而持久的挑战。至关重要的是，在巨大的潜在催化剂设计空间中识别有希望的候选物是资源密集且耗时的，并且该过程涉及传统的实验方法。为了克服这一瓶颈并加速发现，我们系统地研究了固定在石墨氮化碳（g-C3N4）单层上的单个过渡金属（TM）原子（作为TM-g-C3N4 SACs）通过第一性原理高通量筛选降解UDMH的潜力。这种强大的计算方法能够以系统和高效的方式全面评估28种TM-g-C3N4候选物的稳定性、吸附行为和催化活性。值得注意的是，Os-g-C3N4成为首选，通过双端吸附和超低脱氢势垒（0.2702 eV，氨基端）显示出强大的UDMH捕获能力，比基于pt的体系低59%。重要的是，这种高活性与优异的稳定性（结合能：−7.52 eV；溶解电位：0.84 V）和41%的成本降低（90 vs 220 RMB/g）并存。机理分析表明，载氧后金属能带形成和空轨道介导的电子转移协同激活UDMH，而轨道杂化加速了电荷转移。这项工作不仅确立了Os-g-C3N4作为火箭燃料修复的可持续解决方案，而且还提供了可转移到各种污染物降解系统的通用SAC设计蓝图。
{"title":"High-Throughput Screening of g-C3N4-Supported Single-Atom Catalysts for UDMH Dehydrogenation: A First-Principles Strategy","authors":"Hao-yang Wang, Rui Wang, Yuhao Zhu, Xinyu Zhu, Ying Jia","doi":"10.1021/acs.jpcc.5c07143","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c07143","url":null,"abstract":"Unsymmetrical dimethylhydrazine (UDMH), a carcinogenic aerospace propellant, poses severe environmental threats due to its persistence and high toxicity. Despite the proven efficacy of electrocatalytic technology in degrading diverse organic contaminants, the development of electrocatalysts with high stability, activity, and selectivity for efficient UDMH degradation remains a critical and persistent challenge. Crucially, identifying promising candidates among the vast design space of potential catalysts is resource-intensive and time-consuming, and the process involves conventional experimental approaches. To overcome this bottleneck and accelerate discovery, we systematically investigate the potential of single transition metal (TM) atoms anchored on graphitic carbon nitride (g-C<sub>3</sub>N<sub>4</sub>) monolayers─serving as TM-<i>g</i>-C<sub>3</sub>N<sub>4</sub> SACs─for UDMH degradation via first-principles high-throughput screening. This powerful computational approach enables the comprehensive evaluation of stability, adsorption behavior, and catalytic activity across 28 TM-<i>g</i>-C<sub>3</sub>N<sub>4</sub> candidates in a systematic and efficient manner. Remarkably, Os-<i>g</i>-C<sub>3</sub>N<sub>4</sub> emerges as the premier candidate, demonstrating robust UDMH capture via dual-terminal adsorption coupled with an ultralow dehydrogenation barrier (0.2702 eV, amino terminal) that is 59% lower than Pt-based systems. Crucially, this high activity coexists with exceptional stability (binding energy: −7.52 eV; dissolution potential: 0.84 V) and 41% cost reduction (90 vs 220 RMB/g). Mechanistic analysis reveals that metallic band formation post-Os loading and empty-orbital-mediated electron transfer synergistically activate UDMH, while orbital hybridization accelerates charge transfer. This work not only establishes Os-<i>g</i>-C<sub>3</sub>N<sub>4</sub> as a sustainable solution for rocket fuel remediation but also provides a universal SAC design blueprint transferable to diverse pollutant degradation systems.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"39 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146122390","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 : 2026-02-06DOI: 10.1021/acs.jpcc.5c08422
Andrew M. Fitzgerald, Nikoloz Gegechkori, Laura Londoño Fandiño, Dawei Liu, Kateryna Kushnir Friedman, Joshua R. Uzarski, Ivan Baginskiy, Serhii Dukhnovsky, Veronika Zahorodna, Oleksiy Gogotsi, Ronald L. Grimm, Jeannine M. Coburn, Lyubov V. Titova
Ti3C2Tx MXene, the most extensively studied member of the MXene family, combines metallic conductivity, strong light absorption, and exceptional photothermal efficiency, enabling applications ranging from optoelectronics to thermal management and biomedical systems. However, its practical use has been challenged by limited environmental stability. While polyphosphate edge-capping has previously been shown to effectively suppress oxidation and degradation in aqueous suspensions, its influence on the intrinsic electronic properties and photothermal behavior of MXene films has remained unexplored. Here, we investigate the impact of sodium tripolyphosphate (TPP) introduced during aqueous processing on the electrical transport and photothermal dynamics of Ti3C2Tx films. Using terahertz time-domain spectroscopy (THz-TDS) and four-point probe measurements, we find that TPP addition does not significantly alter charge transport or carrier localization, indicating that the electronic structure of the films is preserved. Optical pump–THz probe spectroscopy reveals that, upon photoexcitation, all samples exhibit the characteristic transient suppression of conductivity associated with photothermal heating, followed by a slow recovery over hundreds of picoseconds. At higher TPP concentrations, the thermal relaxation is noticeably slower, suggesting that TPP residues at flake edges and interflake interfaces hinder phonon transport and heat dissipation. These findings demonstrate that addition of polyphosphate, while maintaining the excellent conductivity of Ti3C2Tx, can be used to control photothermal relaxation behavior and the thermal response of MXene-based functional materials.
{"title":"Influence of Tripolyphosphate on Electronic Conductivity and Photothermal Relaxation Dynamics in Ti3C2Tx MXene","authors":"Andrew M. Fitzgerald, Nikoloz Gegechkori, Laura Londoño Fandiño, Dawei Liu, Kateryna Kushnir Friedman, Joshua R. Uzarski, Ivan Baginskiy, Serhii Dukhnovsky, Veronika Zahorodna, Oleksiy Gogotsi, Ronald L. Grimm, Jeannine M. Coburn, Lyubov V. Titova","doi":"10.1021/acs.jpcc.5c08422","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c08422","url":null,"abstract":"Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> MXene, the most extensively studied member of the MXene family, combines metallic conductivity, strong light absorption, and exceptional photothermal efficiency, enabling applications ranging from optoelectronics to thermal management and biomedical systems. However, its practical use has been challenged by limited environmental stability. While polyphosphate edge-capping has previously been shown to effectively suppress oxidation and degradation in aqueous suspensions, its influence on the intrinsic electronic properties and photothermal behavior of MXene films has remained unexplored. Here, we investigate the impact of sodium tripolyphosphate (TPP) introduced during aqueous processing on the electrical transport and photothermal dynamics of Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> films. Using terahertz time-domain spectroscopy (THz-TDS) and four-point probe measurements, we find that TPP addition does not significantly alter charge transport or carrier localization, indicating that the electronic structure of the films is preserved. Optical pump–THz probe spectroscopy reveals that, upon photoexcitation, all samples exhibit the characteristic transient suppression of conductivity associated with photothermal heating, followed by a slow recovery over hundreds of picoseconds. At higher TPP concentrations, the thermal relaxation is noticeably slower, suggesting that TPP residues at flake edges and interflake interfaces hinder phonon transport and heat dissipation. These findings demonstrate that addition of polyphosphate, while maintaining the excellent conductivity of Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub>, can be used to control photothermal relaxation behavior and the thermal response of MXene-based functional materials.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"2 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146135314","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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