The frontier electronic structure of tetraphenylporphyrinato (TPP2-) and phthalocyaninato (Pc2-) square planar transition metal complexes (MTPP and MPc; M = V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) has been revisited through DFT calculations. The different symmetry and spin multiplicity between MPc and MTPP of the same M is shown to originate from the different Pc2- and TPP2- ligand field, stronger in the former ligand than in the latter. The corresponding spatial localization and symmetry of the unoccupied molecular orbitals postulate unescapable geometric constraints to their overlap with the electron cloud of a crystalline metal surface. From comparison with literature experimental evidence, we show that the adsorption geometry (atomic site and azimuthal orientation) of MTPPs and MPcs on the low index crystal planes of coinage metals (CM = Au, Ag, Cu) may be predicted when two conditions are satisfied: i) evidence of a surface → adsorbate charge transfer, ii) absence of significant distortion of the macrocycle upon adsorption. In this regard, the overall susceptibility to charge transfer is determined by the strength of the molecular ligand field (i.e., charge transfer to MPc is more favoured than to MTPP) and inversely linked to the electronegativity of the surface atoms (being Au the most inert CM substrate thanks to its highest electronegativity).
{"title":"Substrate charge transfer drives the absorption site of metal-phthalocyanines and porphyrins on coinage metal surfaces","authors":"Silvia Carlotto, Iulia Cojocariu, Vitaliy Feyer, Luca Schio, Luca Floreano, Maurizio Casarin","doi":"10.1039/d5cp01576f","DOIUrl":"https://doi.org/10.1039/d5cp01576f","url":null,"abstract":"The frontier electronic structure of tetraphenylporphyrinato (TPP<small><sup>2-</sup></small>) and phthalocyaninato (Pc<small><sup>2-</sup></small>) square planar transition metal complexes (MTPP and MPc; M = V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) has been revisited through DFT calculations. The different symmetry and spin multiplicity between MPc and MTPP of the same M is shown to originate from the different Pc<small><sup>2-</sup></small> and TPP<small><sup>2-</sup></small> ligand field, stronger in the former ligand than in the latter. The corresponding spatial localization and symmetry of the unoccupied molecular orbitals postulate unescapable geometric constraints to their overlap with the electron cloud of a crystalline metal surface. From comparison with literature experimental evidence, we show that the adsorption geometry (atomic site and azimuthal orientation) of MTPPs and MPcs on the low index crystal planes of coinage metals (CM = Au, Ag, Cu) may be predicted when two conditions are satisfied: i) evidence of a surface → adsorbate charge transfer, ii) absence of significant distortion of the macrocycle upon adsorption. In this regard, the overall susceptibility to charge transfer is determined by the strength of the molecular ligand field (i.e., charge transfer to MPc is more favoured than to MTPP) and inversely linked to the electronegativity of the surface atoms (being Au the most inert CM substrate thanks to its highest electronegativity).","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"77 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144066170","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}
Cyril Hachemi, Hadi Dib, Mourad Debbichi, Michael Badawi, Calley Eads, Maya Ibrahim, Stéphane Loridant, Jan Knudsen, Helena Kaper, Luis Cardenas
Operando Resonant Photoelectron Spectroscopy (RPES) combined with Modulated Chemical Excitation revealed the dynamic evolution of Ce3+ and Ce4+ redox states at the surface of CeO2 during the CO oxidation reaction. Using alternating CO and O2 pulses as chemically modulated signals, we monitored the surface states in the valence band region, unveiling the evolution of electronic structure during the catalytic process. The analysis with different gas flow ratios revealed that under CO-rich conditions (CO:O2 ≥ 1), only partial conversion from Ce3+ to Ce4+ occurred. In contrast, complete Ce3+ to Ce4+ conversion was achieved when pulsing O2 into O2-rich environments. Furthermore, we find that intermediate oxygen species, such as peroxo and OH, impact the conversion of Ce3+ and Ce4+. These oxygenated species coexist between 330 °C and 360 °C in pure O2, while above 390 °C only OH groups remain stable on the ceria surface.
{"title":"Persistence of Ce3+ Species on the Surface of Ceria during Redox Cycling: A Modulated Chemical Excitation Investigation","authors":"Cyril Hachemi, Hadi Dib, Mourad Debbichi, Michael Badawi, Calley Eads, Maya Ibrahim, Stéphane Loridant, Jan Knudsen, Helena Kaper, Luis Cardenas","doi":"10.1039/d5cp01283j","DOIUrl":"https://doi.org/10.1039/d5cp01283j","url":null,"abstract":"Operando Resonant Photoelectron Spectroscopy (RPES) combined with Modulated Chemical Excitation revealed the dynamic evolution of Ce<small><sup>3+</sup></small> and Ce<small><sup>4+</sup></small> redox states at the surface of CeO<small><sub>2</sub></small> during the CO oxidation reaction. Using alternating CO and O<small><sub>2</sub></small> pulses as chemically modulated signals, we monitored the surface states in the valence band region, unveiling the evolution of electronic structure during the catalytic process. The analysis with different gas flow ratios revealed that under CO-rich conditions (CO:O<small><sub>2</sub></small> ≥ 1), only partial conversion from Ce<small><sup>3+</sup></small> to Ce<small><sup>4+</sup></small> occurred. In contrast, complete Ce<small><sup>3+</sup></small> to Ce<small><sup>4+</sup></small> conversion was achieved when pulsing O<small><sub>2</sub></small> into O<small><sub>2</sub></small>-rich environments. Furthermore, we find that intermediate oxygen species, such as peroxo and OH, impact the conversion of Ce<small><sup>3+</sup></small> and Ce<small><sup>4+</sup></small>. These oxygenated species coexist between 330 °C and 360 °C in pure O<small><sub>2</sub></small>, while above 390 °C only OH groups remain stable on the ceria surface.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"78 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144066135","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}
This paper presents a thorough prediction and investigation of ionization energies, atomic levels, and crystal-field splittings in lanthanide ions. We show that a two-component complete active space (CAS) configuration interaction (CI) approach based on two-component density functional theory (DFT) reference states is suitable to yield accurate excitation energies for lower energy terms. DFT references are further shown to be superior to Hartree-Fock (HF) references for predicting both atomic levels and ionization energies. Especially in the Greens function based GW method used to determine ionization energies, the deficiencies of the wave function based HF references are severe, leading to sizable errors. Two-electron contributions to spin-orbit coupling are found to be an important ingredient for obtaining accurate atomic levels. These contributions are taken into account using a screened-nuclear-spin-orbit (SNSO) approach, which is shown to be very accurate. DFT based CAS-CI is further used to calculate crystal-field splittings. The results are well suited to predict the subtle splittings in complexes with unpaired 4f electrons.
{"title":"Excitations in Lanthanide Ions: A Systematic Evaluation of two-component CAS-CI and GW","authors":"Roman Zielke, Florian Weigend, Christof Holzer","doi":"10.1039/d5cp00780a","DOIUrl":"https://doi.org/10.1039/d5cp00780a","url":null,"abstract":"This paper presents a thorough prediction and investigation of ionization energies, atomic levels, and crystal-field splittings in lanthanide ions. We show that a two-component complete active space (CAS) configuration interaction (CI) approach based on two-component density functional theory (DFT) reference states is suitable to yield accurate excitation energies for lower energy terms. DFT references are further shown to be superior to Hartree-Fock (HF) references for predicting both atomic levels and ionization energies. Especially in the Greens function based GW method used to determine ionization energies, the deficiencies of the wave function based HF references are severe, leading to sizable errors. Two-electron contributions to spin-orbit coupling are found to be an important ingredient for obtaining accurate atomic levels. These contributions are taken into account using a screened-nuclear-spin-orbit (SNSO) approach, which is shown to be very accurate. DFT based CAS-CI is further used to calculate crystal-field splittings. The results are well suited to predict the subtle splittings in complexes with unpaired 4f electrons.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"6 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144066136","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 shock response of poly(p-phenylene terephthalamide) (PPTA) crystals is investigated using molecular dynamics simulations combined with a machine learning potential. Considering the anisotropy of PPTA crystals, the directions dominated by hydrogen bonding and van der Waals forces are examined, respectively. First, a machine learning potential capable of simulating the shock behavior of PPTA is developed and validated. The potential is demonstrated to achieve excellent accuracy, showing high consistency with density functional theory results. Based on the established machine learning potential, multiscale shock techniques are employed to simulate shock compression at various particle velocities. The Hugoniot curves of PPTA crystals reveal three distinct stages of shock response: elastic, plastic, and cross-linking. With increasing particle velocity, the b axis of PPTA crystals is found to exhibit a greater tendency for plastic deformation. Plasticity along the a axis is characterized by the planarization of adjacent benzene rings within the chains, while along the b axis, it involves the breaking and reformation of hydrogen bonds. The spatiotemporal evolution of thermodynamic parameters and spallation during shock wave propagation is further uncovered through non-equilibrium molecular dynamics simulations. The shock response mechanisms of PPTA fibers are elucidated, providing a foundation for subsequent simulations and their application in impact protection structures.
{"title":"Machine-Learning molecular dynamics simulations of Shock Response and Spallation Behavior in PPTA Crystals","authors":"lei liu, Jingfu Shi, Di Song, Changqing Miao","doi":"10.1039/d5cp00251f","DOIUrl":"https://doi.org/10.1039/d5cp00251f","url":null,"abstract":"The shock response of poly(p-phenylene terephthalamide) (PPTA) crystals is investigated using molecular dynamics simulations combined with a machine learning potential. Considering the anisotropy of PPTA crystals, the directions dominated by hydrogen bonding and van der Waals forces are examined, respectively. First, a machine learning potential capable of simulating the shock behavior of PPTA is developed and validated. The potential is demonstrated to achieve excellent accuracy, showing high consistency with density functional theory results. Based on the established machine learning potential, multiscale shock techniques are employed to simulate shock compression at various particle velocities. The Hugoniot curves of PPTA crystals reveal three distinct stages of shock response: elastic, plastic, and cross-linking. With increasing particle velocity, the b axis of PPTA crystals is found to exhibit a greater tendency for plastic deformation. Plasticity along the a axis is characterized by the planarization of adjacent benzene rings within the chains, while along the b axis, it involves the breaking and reformation of hydrogen bonds. The spatiotemporal evolution of thermodynamic parameters and spallation during shock wave propagation is further uncovered through non-equilibrium molecular dynamics simulations. The shock response mechanisms of PPTA fibers are elucidated, providing a foundation for subsequent simulations and their application in impact protection structures.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"30 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144066139","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}
Single-atom catalysts (SACs) have tremendous applications in enhancing the catalytic performance in the electrocatalytic nitrogen reduction reaction (NRR). Carbon-based substrates have superior properties that improve the catalytic performance either by forming defects or by doping heteroatoms, such as B,N-doped graphene, S-doped graphene, and defective carbon nanotubes. However, the carbon nanotube (CNT)-based electrocatalysts for NRR study are currently less explored. Here, we use the FeB2N2-(n,0) CNTs (n = 3-8) as representative electrocatalysts to study the different CNT curvatures and reveal their effects on the NN triple bond activation and adsorption free energy (ΔG) of the *N2 molecule, with changes in the potential-determining step in NRR. Zigzag B2N2-(6,0) CNTs were selected as the efficient substrate, with three transition metal atoms (TM = Fe, Ru and Ir) anchored on the B2N2-(6,0) CNT to construct the NRR catalysts. Using first-principles calculation and the computational hydrogen electrode (CHE) model, we investigated their electrocatalytic performance in NRR. FeB2N2-(6,0) CNT is the most efficient catalyst and has a low limiting potential (UL) of -0.551 V for NRR. Further, the projected partial density of states and projected crystal orbital Hamilton population analyses illustrate that the N2 activation is due to strong π*-backbonding, which leads to effective charge transfer between the active site (metal d-orbital) and N2 molecule (p-orbital). The FeB2N2-(6,0) CNT also showed high NRR selectivity, inhibiting the competitive hydrogen evolution reaction. Our study provides a detailed mechanism of catalysis by the carbon-based, high-efficiency electrocatalyst for NRR and opens up the possibility for experimentalists to further explore the carbon-based one-dimensional electrocatalyst for NRR.
单原子催化剂在提高电催化氮还原反应（NRR）的催化性能方面有着广泛的应用。碳基衬底具有优异的性能，可以通过形成缺陷或掺杂杂原子（如B、n掺杂石墨烯、s掺杂石墨烯和缺陷碳纳米管）来提高催化性能。然而，碳纳米管（CNT）电催化剂用于NRR研究的研究目前较少。本文以FeB2N2-(n,0)碳纳米管（n = 3-8）为代表性电催化剂，研究了不同碳纳米管曲率对*N2分子n - n - n三键活化和吸附自由能（ΔG）的影响，以及NRR中电位决定步骤的变化。选择锯齿形B2N2-(6,0)碳纳米管作为高效底物，将三个过渡金属原子（TM = Fe、Ru和Ir）固定在B2N2-(6,0)碳纳米管上构建NRR催化剂。利用第一性原理计算和计算氢电极（CHE）模型，研究了它们在NRR中的电催化性能。FeB2N2-(6,0)碳纳米管是最有效的催化剂，其NRR极限电位（UL）较低，为-0.551 V。此外，投影态偏密度和投影晶体轨道Hamilton居群分析表明，N2活化是由强π*背键引起的，这导致了活性位点（金属d轨道）和N2分子（p轨道）之间的有效电荷转移。FeB2N2-(6,0)碳纳米管也表现出较高的NRR选择性，抑制了竞争性析氢反应。本研究提供了碳基高效电催化剂催化NRR的详细机理，为实验人员进一步探索碳基一维NRR电催化剂提供了可能。
{"title":"Tuning surface curvature in B and N co-doped CNT-derived Fe, Ru and Ir catalysts for electrochemical hydrogenation of N2 to NH3.","authors":"Deewan S Teja,Bhabani S Mallik","doi":"10.1039/d5cp00309a","DOIUrl":"https://doi.org/10.1039/d5cp00309a","url":null,"abstract":"Single-atom catalysts (SACs) have tremendous applications in enhancing the catalytic performance in the electrocatalytic nitrogen reduction reaction (NRR). Carbon-based substrates have superior properties that improve the catalytic performance either by forming defects or by doping heteroatoms, such as B,N-doped graphene, S-doped graphene, and defective carbon nanotubes. However, the carbon nanotube (CNT)-based electrocatalysts for NRR study are currently less explored. Here, we use the FeB2N2-(n,0) CNTs (n = 3-8) as representative electrocatalysts to study the different CNT curvatures and reveal their effects on the NN triple bond activation and adsorption free energy (ΔG) of the *N2 molecule, with changes in the potential-determining step in NRR. Zigzag B2N2-(6,0) CNTs were selected as the efficient substrate, with three transition metal atoms (TM = Fe, Ru and Ir) anchored on the B2N2-(6,0) CNT to construct the NRR catalysts. Using first-principles calculation and the computational hydrogen electrode (CHE) model, we investigated their electrocatalytic performance in NRR. FeB2N2-(6,0) CNT is the most efficient catalyst and has a low limiting potential (UL) of -0.551 V for NRR. Further, the projected partial density of states and projected crystal orbital Hamilton population analyses illustrate that the N2 activation is due to strong π*-backbonding, which leads to effective charge transfer between the active site (metal d-orbital) and N2 molecule (p-orbital). The FeB2N2-(6,0) CNT also showed high NRR selectivity, inhibiting the competitive hydrogen evolution reaction. Our study provides a detailed mechanism of catalysis by the carbon-based, high-efficiency electrocatalyst for NRR and opens up the possibility for experimentalists to further explore the carbon-based one-dimensional electrocatalyst for NRR.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"36 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144065656","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}
Fahad Abdulaziz,Mohamed Zayed,Salman Latif,Yassin A Jeilani,Mohamed Shaban,Raja Rama Devi Patel,Hussein A Elsayed,Mohamed Rabia,Ashour M Ahmed
This study explores a novel photoelectrode composed of copper oxide (CuO), polyaniline (PANI), and gold (Au) for efficient hydrogen production through photoelectrochemical (PEC) water splitting. Structural and morphological analyses using various techniques confirm the successful fabrication of the ternary Au/PANI/CuO photoelectrode. The integration of Au, PANI, and CuO nanomaterials enhances light harvesting, facilitates charge transfer, and reduces charge recombination due to the plasmonic effect of Au and the synergistic interaction between PANI and CuO. The Au/PANI/CuO photoelectrode achieves a 300-fold increase in photocurrent density (15 mA cm-2 at -0.39 V vs. RHE) compared to pure CuO. Additionally, it demonstrates superior operational stability for 5 hours and records an IPCE of 45% at 500 nm. These findings pave the way for the development of high-performance and durable plasmonic/polymer/semiconductor photoelectrodes for sustainable and clean hydrogen generation.
本研究探索了一种由氧化铜（CuO）、聚苯胺（PANI）和金（Au）组成的新型光电极，用于通过光电化学（PEC）水分解高效制氢。利用各种技术对Au/PANI/CuO三元光电极进行了结构和形态分析，证实了该电极的成功制备。Au， PANI和CuO纳米材料的集成增强了光捕获，促进了电荷转移，并减少了由于Au的等离子体效应和PANI与CuO之间的协同相互作用而产生的电荷重组。与纯CuO相比，Au/PANI/CuO光电极的光电流密度增加了300倍（在-0.39 V与RHE下为15 mA cm-2）。此外，它在5小时内表现出卓越的运行稳定性，并在500纳米处记录了45%的IPCE。这些发现为开发高性能和耐用的等离子体/聚合物/半导体光电极铺平了道路，用于可持续和清洁的制氢。
{"title":"Fabrication of gold/polyaniline/copper oxide electrode for efficient photoelectrochemical hydrogen evolution.","authors":"Fahad Abdulaziz,Mohamed Zayed,Salman Latif,Yassin A Jeilani,Mohamed Shaban,Raja Rama Devi Patel,Hussein A Elsayed,Mohamed Rabia,Ashour M Ahmed","doi":"10.1039/d5cp00350d","DOIUrl":"https://doi.org/10.1039/d5cp00350d","url":null,"abstract":"This study explores a novel photoelectrode composed of copper oxide (CuO), polyaniline (PANI), and gold (Au) for efficient hydrogen production through photoelectrochemical (PEC) water splitting. Structural and morphological analyses using various techniques confirm the successful fabrication of the ternary Au/PANI/CuO photoelectrode. The integration of Au, PANI, and CuO nanomaterials enhances light harvesting, facilitates charge transfer, and reduces charge recombination due to the plasmonic effect of Au and the synergistic interaction between PANI and CuO. The Au/PANI/CuO photoelectrode achieves a 300-fold increase in photocurrent density (15 mA cm-2 at -0.39 V vs. RHE) compared to pure CuO. Additionally, it demonstrates superior operational stability for 5 hours and records an IPCE of 45% at 500 nm. These findings pave the way for the development of high-performance and durable plasmonic/polymer/semiconductor photoelectrodes for sustainable and clean hydrogen generation.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"53 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144065957","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}
Albert Rimola, Alicja Bulik, Berta Martínez-Bachs, Niccolò Bancone, Eric Mates-Torres, Marta Corno, Piero Ugliengo
In the coldest, densest regions of the interstellar medium (ISM), dust grains are covered by thick ice mantles dominated mainly by water. Although more than 300 species have been detected in the gas phase of the ISM by their rotational emission lines within the radio frequency range, only a few were found in interstellar ices, e.g. CO, CO2, NH3, CH3OH, CH4 and OCS, by means of infrared (IR) spectroscopy. Observations of ices require a background-illuminating source for absorption, constraining the available sight lines for investigation. Further challenges arise when comparing with laboratory spectra due to the influence of temperature, ice structure and the presence of other species. In the era of IR observations provided by the James Webb Space Telescope (JWST), it is crucial to provide reference spectral data confirming JWST's assigned features. For this purpose, this study addresses the adsorption of the aforementioned species on water ice surfaces and their IR features by means of quantum chemical computations grounded on the density functional theory (DFT) hybrid B3LYP-D3(BJ) functional, known to give reliable results for binding energy and vibrational frequency calculations, including IR spectra simulation. The calculated binding energies and IR spectral data are presented in the context of experimental spectra of ices and the new findings from the JWST, which have already proven to be insightful thanks to its unmatched sensitivity. We show that quantum chemistry is a powerful tool for accurate frequency calculations of ISM ice interfaces, providing unprecedented insights into their IR signatures.
{"title":"Predicting accurate binding energies and vibrational spectroscopic features of interstellar icy species. A quantum mechanical study","authors":"Albert Rimola, Alicja Bulik, Berta Martínez-Bachs, Niccolò Bancone, Eric Mates-Torres, Marta Corno, Piero Ugliengo","doi":"10.1039/d5cp01151e","DOIUrl":"https://doi.org/10.1039/d5cp01151e","url":null,"abstract":"In the coldest, densest regions of the interstellar medium (ISM), dust grains are covered by thick ice mantles dominated mainly by water. Although more than 300 species have been detected in the gas phase of the ISM by their rotational emission lines within the radio frequency range, only a few were found in interstellar ices, e.g. CO, CO<small><sub>2</sub></small>, NH<small><sub>3</sub></small>, CH<small><sub>3</sub></small>OH, CH<small><sub>4</sub></small> and OCS, by means of infrared (IR) spectroscopy. Observations of ices require a background-illuminating source for absorption, constraining the available sight lines for investigation. Further challenges arise when comparing with laboratory spectra due to the influence of temperature, ice structure and the presence of other species. In the era of IR observations provided by the James Webb Space Telescope (JWST), it is crucial to provide reference spectral data confirming JWST's assigned features. For this purpose, this study addresses the adsorption of the aforementioned species on water ice surfaces and their IR features by means of quantum chemical computations grounded on the density functional theory (DFT) hybrid B3LYP-D3(BJ) functional, known to give reliable results for binding energy and vibrational frequency calculations, including IR spectra simulation. The calculated binding energies and IR spectral data are presented in the context of experimental spectra of ices and the new findings from the JWST, which have already proven to be insightful thanks to its unmatched sensitivity. We show that quantum chemistry is a powerful tool for accurate frequency calculations of ISM ice interfaces, providing unprecedented insights into their IR signatures.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"29 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144066137","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}
K. A. Arnab, M. Stephens, I. Maxfield, C. Lee, E. Ertekin, Y. K. Frodason, J. B. Varley, M. A. Scarpulla
β-Gallium oxide (β-Ga2O3) is of high interest for power electronics because of its unique combination of melt growth, epitaxial growth, n-type dopability, ultrawide bandgap, and high critical field. Optimization of crystal growth processes to promote beneficial defects and suppress harmful ones requires accurate quantitative modelling of both native and impurity defects. Herein we quantitatively model defect concentrations as a function of bulk crystal growth conditions and demonstrate the necessity of including effects such as bandgap temperature dependence, chemical potentials from thermochemistry, and defect vibrational entropy in modelling based on defect formation energies computed by density functional theory (DFT) with hybrid functionals. Without these contributions, grossly-erroneous and misleading predictions arise, e.g. that n-type doping attempts would be fully compensated by Ga vacancies. Including these effects reproduces the experimental facts that melt-grown Sn-doped β-Ga2O3 crystals are conductive with small compensation while annealing the same crystals in O2 at intermediate temperatures renders them insulating. To accomplish this modeling, we developed a comprehensive modelling framework (KROGER) based on calculated defect formation energies and flexible thermodynamic conditions. These capabilities allow KROGER to capture full and partial defect equilibria amongst native defects and impurities occurring during specific semiconductor growth or fabrication processes. We use KROGER to model 873 charge-states of 259 defects involving 19 elements in conditions representing bulk crystal growth by edge-fed growth (EFG) and annealing in oxygen. Our methodology is transferrable to a wide range of materials beyond β-Ga2O3. The integration of thermodynamic and first-principles modelling of point defects provides insight into optimization of point defect populations in growth and processing.
{"title":"Quantitative modeling of point defects in β-Ga2O3 combining hybrid functional energetics with semiconductor and processes thermodynamics","authors":"K. A. Arnab, M. Stephens, I. Maxfield, C. Lee, E. Ertekin, Y. K. Frodason, J. B. Varley, M. A. Scarpulla","doi":"10.1039/d4cp04817b","DOIUrl":"https://doi.org/10.1039/d4cp04817b","url":null,"abstract":"β-Gallium oxide (β-Ga<small><sub>2</sub></small>O<small><sub>3</sub></small>) is of high interest for power electronics because of its unique combination of melt growth, epitaxial growth, n-type dopability, ultrawide bandgap, and high critical field. Optimization of crystal growth processes to promote beneficial defects and suppress harmful ones requires accurate quantitative modelling of both native and impurity defects. Herein we quantitatively model defect concentrations as a function of bulk crystal growth conditions and demonstrate the necessity of including effects such as bandgap temperature dependence, chemical potentials from thermochemistry, and defect vibrational entropy in modelling based on defect formation energies computed by density functional theory (DFT) with hybrid functionals. Without these contributions, grossly-erroneous and misleading predictions arise, <em>e.g.</em> that n-type doping attempts would be fully compensated by Ga vacancies. Including these effects reproduces the experimental facts that melt-grown Sn-doped β-Ga<small><sub>2</sub></small>O<small><sub>3</sub></small> crystals are conductive with small compensation while annealing the same crystals in O<small><sub>2</sub></small> at intermediate temperatures renders them insulating. To accomplish this modeling, we developed a comprehensive modelling framework (KROGER) based on calculated defect formation energies and flexible thermodynamic conditions. These capabilities allow KROGER to capture full and partial defect equilibria amongst native defects and impurities occurring during specific semiconductor growth or fabrication processes. We use KROGER to model 873 charge-states of 259 defects involving 19 elements in conditions representing bulk crystal growth by edge-fed growth (EFG) and annealing in oxygen. Our methodology is transferrable to a wide range of materials beyond β-Ga<small><sub>2</sub></small>O<small><sub>3</sub></small>. The integration of thermodynamic and first-principles modelling of point defects provides insight into optimization of point defect populations in growth and processing.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"42 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144066172","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}
Controllable phase transitions between distinct polymorphs in transition metal dichalcogenides (TMDs) hold great significance for applications in nanoscale electronics. Currently, constructing nanoscale heterojunctions with the desired TMD phase remains challenging due to insufficient control. In this study, we provided a new strategy of phase transitions by controllable mechanical collision of TMD islands containing over thousands of atoms. Using an in situ scanning tunneling microscopy (STM) tip manipulation technique, we can precisely control the fixed-axis rotation of nanoscale NbSe2 islands. Through mechanically colliding T- and H-NbSe2 with each other, we successfully triggered a phase transition from Mott insulator T-NbSe2 to semi-metal H-NbSe2, thereby creating a high-quality heterojunction. We further unveiled the unusual electronic properties of this heterojunction, and provided new insights into the phase transition mechanisms in TMDs and their potential applications in nanoscale electronics.
{"title":"Nanoscale island manipulation and construction of heterojunctions by mechanical collision of 2D materials.","authors":"Xiongbai Cao,Liangguang Jia,Huixia Yang,Zhenru Zhou,Tingting Wang,Haolong Fan,Yan Li,Xiaoyu Hao,Lingtao Zhan,Qinze Yu,Liwei Liu,Teng Zhang,Quanzhen Zhang,Yeliang Wang","doi":"10.1039/d5cp01339a","DOIUrl":"https://doi.org/10.1039/d5cp01339a","url":null,"abstract":"Controllable phase transitions between distinct polymorphs in transition metal dichalcogenides (TMDs) hold great significance for applications in nanoscale electronics. Currently, constructing nanoscale heterojunctions with the desired TMD phase remains challenging due to insufficient control. In this study, we provided a new strategy of phase transitions by controllable mechanical collision of TMD islands containing over thousands of atoms. Using an in situ scanning tunneling microscopy (STM) tip manipulation technique, we can precisely control the fixed-axis rotation of nanoscale NbSe2 islands. Through mechanically colliding T- and H-NbSe2 with each other, we successfully triggered a phase transition from Mott insulator T-NbSe2 to semi-metal H-NbSe2, thereby creating a high-quality heterojunction. We further unveiled the unusual electronic properties of this heterojunction, and provided new insights into the phase transition mechanisms in TMDs and their potential applications in nanoscale electronics.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"28 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144065657","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}
Roman Fedorenko, Liya Poletavkina, Vasiliy Andreevich Trukhanov, Konstantin N. Kuklin, Dmitry Balakirev, Ivan Dyadishchev, Nikita S. Saratovsky, Artem V Bakirov, Sergey Ponomarenko, Yuriy N. Luponosov, Dmitry Paraschuk, Andrey Yurievich Sosorev
Rational molecular design can yield novel organic semiconductors (OSs) with superior properties. In this study, we show that introduction of oxygen atom in the terminal alkyl groups of diphenyl-substituted BTBT derivative improves a number of important properties of the material. Specifically, we synthesized 2,7-bis(4-decyloxyphenyl)[1]benzothieno[3,2-b][1]benzothiophene (DOPBTBT) and compared it with its oxygen-free counterpart DPBTBT. We show that the oxygen-containing molecule is considerably more stable against thermal oxidation, and the corresponding crystals have no phase transitions from room temperature up to 150 °C. Photoluminescence quantum yield is also higher for this molecule and reaches 48%. The charge mobility thin films is about three times higher for DOPBTBT and reaches 0.74 cm2V-1s-1; moreover, it is stable in the course of about one month in ambient conditions. OFETs based on monolayer of DOPBTBT molecules demonstrate high charge mobility of 1.1 cm2V-1s-1, which is among the largest observed for monolayer devices. Finally, we show that DOPBTBT can be used in light-emitting and photo transistors. The results obtained highlight that addition of oxygen atoms into the terminal alkyl substituents of BTBT derivatives is a promising tool for molecular design towards high-mobility and stable organic semiconductors for organic optoelectronic devices.
{"title":"Decyloxy-substituted BTBT derivative for highly efficient and stable thin-film organic (opto)electronic devices","authors":"Roman Fedorenko, Liya Poletavkina, Vasiliy Andreevich Trukhanov, Konstantin N. Kuklin, Dmitry Balakirev, Ivan Dyadishchev, Nikita S. Saratovsky, Artem V Bakirov, Sergey Ponomarenko, Yuriy N. Luponosov, Dmitry Paraschuk, Andrey Yurievich Sosorev","doi":"10.1039/d5cp01459j","DOIUrl":"https://doi.org/10.1039/d5cp01459j","url":null,"abstract":"Rational molecular design can yield novel organic semiconductors (OSs) with superior properties. In this study, we show that introduction of oxygen atom in the terminal alkyl groups of diphenyl-substituted BTBT derivative improves a number of important properties of the material. Specifically, we synthesized 2,7-bis(4-decyloxyphenyl)[1]benzothieno[3,2-b][1]benzothiophene (DOPBTBT) and compared it with its oxygen-free counterpart DPBTBT. We show that the oxygen-containing molecule is considerably more stable against thermal oxidation, and the corresponding crystals have no phase transitions from room temperature up to 150 °C. Photoluminescence quantum yield is also higher for this molecule and reaches 48%. The charge mobility thin films is about three times higher for DOPBTBT and reaches 0.74 cm2V-1s-1; moreover, it is stable in the course of about one month in ambient conditions. OFETs based on monolayer of DOPBTBT molecules demonstrate high charge mobility of 1.1 cm2V-1s-1, which is among the largest observed for monolayer devices. Finally, we show that DOPBTBT can be used in light-emitting and photo transistors. The results obtained highlight that addition of oxygen atoms into the terminal alkyl substituents of BTBT derivatives is a promising tool for molecular design towards high-mobility and stable organic semiconductors for organic optoelectronic devices.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":"42 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144066082","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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