Pub Date : 2024-12-10DOI: 10.1016/j.chemphys.2024.112538
Andrey G. Smolin
The influence of the hydrogen bonding between the isoalloxazine ring system and the ribityl chain on the fluorescence decay times is shown. A conformational analysis of the riboflavin molecule in an aqueous solution was carried out. Ab initio calculations were carried out using density functional theory, where functional were extended with Grimme’s dispersion correction. Conformers of riboflavin in the neutral form with the lowest energy values in water were determined. These conformers have the hydrogen bonding between the ribityl chain and the nitrogen atom in the isoalloxazine ring system. It was shown that for riboflavin and FAD(2-) molecules there are similar hydrogen bonding between the isoalloxazine ring system and the ribityl chain. The process of the isoalloxazine ring protonation in riboflavin and FAD(2-) conformers with the hydrogen bonding upon interaction with hydronium can be carried out through the proton transfer process from the oxygen atom at the ribityl chain.
{"title":"Conformational analysis of riboflavin in aqueous solution: The influence of hydrogen bonding in riboflavin and FAD(2-) molecules on fluorescence parameters","authors":"Andrey G. Smolin","doi":"10.1016/j.chemphys.2024.112538","DOIUrl":"10.1016/j.chemphys.2024.112538","url":null,"abstract":"<div><div>The influence of the hydrogen bonding between the isoalloxazine ring system and the ribityl chain on the fluorescence decay times is shown. A conformational analysis of the riboflavin molecule in an aqueous solution was carried out. <em>Ab initio</em> calculations were carried out using density functional theory, where functional were extended with Grimme’s dispersion correction. Conformers of riboflavin in the neutral form with the lowest energy values in water were determined. These conformers have the hydrogen bonding between the ribityl chain and the nitrogen atom in the isoalloxazine ring system. It was shown that for riboflavin and FAD(2-) molecules there are similar hydrogen bonding between the isoalloxazine ring system and the ribityl chain. The process of the isoalloxazine ring protonation in riboflavin and FAD(2-) conformers with the hydrogen bonding upon interaction with hydronium can be carried out through the proton transfer process from the oxygen atom at the ribityl chain.</div></div>","PeriodicalId":272,"journal":{"name":"Chemical Physics","volume":"591 ","pages":"Article 112538"},"PeriodicalIF":2.0,"publicationDate":"2024-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164762","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 : 2024-12-10DOI: 10.1016/j.chemphys.2024.112572
Imtiaz Ahmad , Rahim Jan
This research investigates the complex processes involved in optimizing assembly conditions to achieve more precise control over the arrangement of gold nanorods (GNRs). The focus is on examining the complex morphology and refinement of GNRs coated with cetyltrimethylammonium bromide (CTAB) within liquid crystalline (LC) structures, with an emphasis on quantifying intertwined domains and the coexistence of diverse particle shapes. The study reveals the presence of morphologically refined arrays of gold nanorod superstructures and explores the influence of factors such as steric hindrance and surface energy on the unique behaviors of these nanostructures in aqueous environments. A combination of experimental and theoretical methods uncovers the significance of energy variances in improving separation efficiency and elucidates the relationship between absorbance, density, and interparticle distances. The research underscores the importance of optimal aspect ratios and their impact on liquid crystal phases, offering valuable insights for the advancement of nanoparticle systems and future innovations in this domain.
{"title":"Purification of distinct nano shapes from a mixtures of rods and spheres","authors":"Imtiaz Ahmad , Rahim Jan","doi":"10.1016/j.chemphys.2024.112572","DOIUrl":"10.1016/j.chemphys.2024.112572","url":null,"abstract":"<div><div>This research investigates the complex processes involved in optimizing assembly conditions to achieve more precise control over the arrangement of gold nanorods (GNRs). The focus is on examining the complex morphology and refinement of GNRs coated with cetyltrimethylammonium bromide (CTAB) within liquid crystalline (LC) structures, with an emphasis on quantifying intertwined domains and the coexistence of diverse particle shapes. The study reveals the presence of morphologically refined arrays of gold nanorod superstructures and explores the influence of factors such as steric hindrance and surface energy on the unique behaviors of these nanostructures in aqueous environments. A combination of experimental and theoretical methods uncovers the significance of energy variances in improving separation efficiency and elucidates the relationship between absorbance, density, and interparticle distances. The research underscores the importance of optimal aspect ratios and their impact on liquid crystal phases, offering valuable insights for the advancement of nanoparticle systems and future innovations in this domain.</div></div>","PeriodicalId":272,"journal":{"name":"Chemical Physics","volume":"591 ","pages":"Article 112572"},"PeriodicalIF":2.0,"publicationDate":"2024-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164761","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 : 2024-12-07DOI: 10.1016/j.chemphys.2024.112577
Jiabing Liu, Shan Qing, Xiaoyan Huang, Ming Ma, Xiaohui Zhang
The thermal transport at the solid-liquid interface at the nanoscale plays a crucial role in the fields of micro-nano devices, chips and nanofluids. However, the microscopic mechanism of thermal transport at the solid-liquid interface, especially considering the influence of surface nanostructures and interface coupling strength, is still unclear. In this study, the interfacial thermal transport in Cu-water confined nanochannels is studied based on Molecular Dynamics simulation. Research indicates that interface thermal transport can be enhanced by introducing surface nanostructures and changing interface coupling strength. The interfacial thermal conductance increases monotonically with the height of the nanostructure, and this trend becomes more pronounced under strong liquid interaction. Under the strong solid-liquid interaction, more water molecules are adsorbed on the Cu surface, forming a more stable adsorption layer, thereby strengthening the solid-liquid interface vibration coupling thermal transport effect. This study provides valuable insights for improving the heat conduction efficiency in confined nanochannels.
{"title":"Molecular dynamics study on the impact of surface nanostructures and interfacial coupling strength on thermal transport at the Cu-water interface","authors":"Jiabing Liu, Shan Qing, Xiaoyan Huang, Ming Ma, Xiaohui Zhang","doi":"10.1016/j.chemphys.2024.112577","DOIUrl":"10.1016/j.chemphys.2024.112577","url":null,"abstract":"<div><div>The thermal transport at the solid-liquid interface at the nanoscale plays a crucial role in the fields of micro-nano devices, chips and nanofluids. However, the microscopic mechanism of thermal transport at the solid-liquid interface, especially considering the influence of surface nanostructures and interface coupling strength, is still unclear. In this study, the interfacial thermal transport in Cu-water confined nanochannels is studied based on Molecular Dynamics simulation. Research indicates that interface thermal transport can be enhanced by introducing surface nanostructures and changing interface coupling strength. The interfacial thermal conductance increases monotonically with the height of the nanostructure, and this trend becomes more pronounced under strong liquid interaction. Under the strong solid-liquid interaction, more water molecules are adsorbed on the Cu surface, forming a more stable adsorption layer, thereby strengthening the solid-liquid interface vibration coupling thermal transport effect. This study provides valuable insights for improving the heat conduction efficiency in confined nanochannels.</div></div>","PeriodicalId":272,"journal":{"name":"Chemical Physics","volume":"591 ","pages":"Article 112577"},"PeriodicalIF":2.0,"publicationDate":"2024-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164760","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 : 2024-12-06DOI: 10.1016/j.chemphys.2024.112564
Hong-xia LIU , Ling FU , Chao-zheng HE
In this work, we use density functional theory (DFT) method to study the catalytic role of Bn (n = 3–5) and Cu-doped B clusters in CO2 hydrogenation reduction reaction. The results show that CuBn-1 reduces the adsorption capacity of reactants and intermediates compared with Bn clusters, indicating that the catalytic performance of electron-deficient clusters is better. The energy barrier of CO2 reduction to CO on Bn and CuBn-1 clusters is 0.65 eV and 0.58 eV, respectively. Cu doping reduces the CO2 catalytic reduction ability of Bn clusters. In addition, our results show that the rate of CO2 catalytic reduction reaction is directly proportional to temperature, and the reaction is rapid under high temperature conditions. In summary, the theoretical results support the mechanism of CO2 reduction reaction, that is, the key role of promoting CO2 hydrogenation through formic acid intermediates.
{"title":"Theoretical prediction of the reaction mechanism underlying the active phase of Bn (n = 3–5) and Cu-doped electron deficient Bn-1 clusters: Reduction of CO2","authors":"Hong-xia LIU , Ling FU , Chao-zheng HE","doi":"10.1016/j.chemphys.2024.112564","DOIUrl":"10.1016/j.chemphys.2024.112564","url":null,"abstract":"<div><div>In this work, we use density functional theory (DFT) method to study the catalytic role of Bn<!--> <!-->(n = 3–5) and Cu-doped B clusters in CO2<!--> <!-->hydrogenation reduction reaction. The results show that CuBn-1<!--> <!-->reduces the adsorption capacity of reactants and intermediates compared with Bn<!--> <!-->clusters, indicating that the catalytic performance of electron-deficient clusters is better. The energy barrier of CO2<!--> <!-->reduction to CO on Bn<!--> <!-->and CuBn-1<!--> <!-->clusters is 0.65 eV and 0.58 eV, respectively. Cu doping reduces the CO2<!--> <!-->catalytic reduction ability of Bn<!--> <!-->clusters. In addition, our results show that the rate of CO2<!--> <!-->catalytic reduction reaction is directly proportional to temperature, and the reaction is rapid under high temperature conditions. In summary, the theoretical results support the mechanism of CO2<!--> <!-->reduction reaction, that is, the key role of promoting CO2<!--> <!-->hydrogenation through formic acid intermediates.</div></div>","PeriodicalId":272,"journal":{"name":"Chemical Physics","volume":"591 ","pages":"Article 112564"},"PeriodicalIF":2.0,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164759","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 : 2024-12-05DOI: 10.1016/j.chemphys.2024.112565
A.V. Gil Rebaza , A. Shankar , Abeer E. Aly
This study employs density functional theory (DFT) to investigate the optical, electronic, mechanical, and structural properties of lead-free double perovskites, specifically Rb2B’AgBr6 (B’ = Ga, Al, In). The findings indicate that Rb2B’AgBr6 compounds exhibit remarkable stability, demonstrated by their highly negative formation energies and favorable mechanical properties, including high ductility and isotropic behavior. Band structure analysis, performed using the modified Becke-Johnson potential, reveals tunable semiconducting behavior. Among the compounds, Rb2B’AgBr6with B’ = Ga displays a larger band gap (3.07 eV), making it suitable for UV–visible applications, while the narrower band gap (1.90 eV) observed for B’ = In suggests suitability for infrared optoelectronic applications. So Rb2AlAgBr6 has a band gap of 3.07 eV, suitable for UV–visible applications, and Rb2InAgBr6, with a 1.90 eV band gap, is suitable for infrared applications.Optical analysis shows strong absorption in the visible spectrum, highlighting the potential of these materials for solar energy devices. These results underscore the promise of Rb2B’AgBr6 compounds as lead-free, sustainable alternatives for optoelectronic applications, supporting advancements in green energy technology. Future experimental validation and exploration of dopants could further enhance device performance based on these theoretical insights.
Novelty Statement
This study presents a thorough investigation of the mechanical and optoelectronic properties of Rb2B’AgBr6 double perovskites through a DFT framework, distinguishing itself by identifying Rb2AlAgBr6 as the most mechanically robust and stable configuration among the studied compounds. The research highlights the unique tunability of the band gap, facilitating targeted applications in both visible and infrared optoelectronics. Additionally, the emphasis on lead-free materials addresses pressing environmental concerns, positioning Rb-based double perovskites as innovative candidates in the quest for sustainable and efficient energy solutions. The comprehensive analysis of structural, electronic, and optical properties offers a foundation for future experimental work and further optimization of these materials in practical applications.
{"title":"Structural, Electronic, and mechanical insights into Rb2B’AgBr6 (B’ = Ga, Al, In) double Perovskites: Pathways to Lead-Free optoelectronics","authors":"A.V. Gil Rebaza , A. Shankar , Abeer E. Aly","doi":"10.1016/j.chemphys.2024.112565","DOIUrl":"10.1016/j.chemphys.2024.112565","url":null,"abstract":"<div><div>This study employs density functional theory (DFT) to investigate the optical, electronic, mechanical, and structural properties of lead-free double perovskites, specifically Rb<sub>2</sub>B’AgBr<sub>6</sub> (B’ = Ga, Al, In). The findings indicate that Rb<sub>2</sub>B’AgBr<sub>6</sub> compounds exhibit remarkable stability, demonstrated by their highly negative formation energies and favorable mechanical properties, including high ductility and isotropic behavior. Band structure analysis, performed using the modified Becke-Johnson potential, reveals tunable semiconducting behavior. Among the compounds, Rb<sub>2</sub>B’AgBr<sub>6</sub>with B’ = Ga displays a larger band gap (3.07 eV), making it suitable for UV–visible applications, while the narrower band gap (1.90 eV) observed for B’ = In suggests suitability for infrared optoelectronic applications. So Rb<sub>2</sub>AlAgBr<sub>6</sub> has a band gap of 3.07 eV, suitable for UV–visible applications, and Rb<sub>2</sub>InAgBr<sub>6</sub>, with a 1.90 eV band gap, is suitable for infrared applications.Optical analysis shows strong absorption in the visible spectrum, highlighting the potential of these materials for solar energy devices. These results underscore the promise of Rb<sub>2</sub>B’AgBr<sub>6</sub> compounds as lead-free, sustainable alternatives for optoelectronic applications, supporting advancements in green energy technology. Future experimental validation and exploration of dopants could further enhance device performance based on these theoretical insights.</div></div><div><h3>Novelty Statement</h3><div>This study presents a thorough investigation of the mechanical and optoelectronic properties of Rb<sub>2</sub>B’AgBr<sub>6</sub> double perovskites through a DFT framework, distinguishing itself by identifying Rb<sub>2</sub>AlAgBr<sub>6</sub> as the most mechanically robust and stable configuration among the studied compounds. The research highlights the unique tunability of the band gap, facilitating targeted applications in both visible and infrared optoelectronics. Additionally, the emphasis on lead-free materials addresses pressing environmental concerns, positioning Rb-based double perovskites as innovative candidates in the quest for sustainable and efficient energy solutions. The comprehensive analysis of structural, electronic, and optical properties offers a foundation for future experimental work and further optimization of these materials in practical applications.</div></div>","PeriodicalId":272,"journal":{"name":"Chemical Physics","volume":"591 ","pages":"Article 112565"},"PeriodicalIF":2.0,"publicationDate":"2024-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164756","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 : 2024-12-03DOI: 10.1016/j.chemphys.2024.112563
Tao Xu , Li Hu , Wenhua Zha , Xiaohu Liu , Rengui Huang , Weixin Shao , Bingwen Wang
In this study, molecular dynamics simulations were used to investigate the changing pattern of Na-vermiculite (Na-VMT) with increasing water content, as well as the swelling characteristics under different hydration states, and to compare with experimental results of other scholars. The simulation results indicate that as the water content in Na-VMT increases, the interlayer space expands, leading to a reduction in the binding force of the clay mineral layer on Na+, thus promoting the hydration and diffusion of Na+. During the hydration transition of Na-VMT, the interaction between water molecules and Na+ ions gradually strengthens, leading some Na+ to shift from inner-sphere to outer-sphere coordination. Due to differences in substitution positions and charge density, the interlayer binding force of Na-VMT is stronger than that of Na-montmorillonite (Na-MMT), resulting in fewer outer-sphere coordinated Na+ ions, smaller hydration parameters, and lower self-diffusion coefficients for Na-VMT.
{"title":"Molecular dynamics simulation of hydration expansion characteristics of Na-vermiculite","authors":"Tao Xu , Li Hu , Wenhua Zha , Xiaohu Liu , Rengui Huang , Weixin Shao , Bingwen Wang","doi":"10.1016/j.chemphys.2024.112563","DOIUrl":"10.1016/j.chemphys.2024.112563","url":null,"abstract":"<div><div>In this study, molecular dynamics simulations were used to investigate the changing pattern of Na-vermiculite (Na-VMT) with increasing water content, as well as the swelling characteristics under different hydration states, and to compare with experimental results of other scholars. The simulation results indicate that as the water content in Na-VMT increases, the interlayer space expands, leading to a reduction in the binding force of the clay mineral layer on Na<sup>+</sup>, thus promoting the hydration and diffusion of Na<sup>+</sup>. During the hydration transition of Na-VMT, the interaction between water molecules and Na<sup>+</sup> ions gradually strengthens, leading some Na<sup>+</sup> to shift from inner-sphere to outer-sphere coordination. Due to differences in substitution positions and charge density, the interlayer binding force of Na-VMT is stronger than that of Na-montmorillonite (Na-MMT), resulting in fewer outer-sphere coordinated Na<sup>+</sup> ions, smaller hydration parameters, and lower self-diffusion coefficients for Na-VMT.</div></div>","PeriodicalId":272,"journal":{"name":"Chemical Physics","volume":"591 ","pages":"Article 112563"},"PeriodicalIF":2.0,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164758","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 : 2024-12-02DOI: 10.1016/j.chemphys.2024.112562
Hongxv Shi , Yue Liang , Baoming Hou , Yuheng Li , Meiqi Liu , Yuyu Pan , Bing Yang
The design and synthesis of low-cost-efficient sensitizer dyes is the most important approach to extend the application of dye-sensitized solar cells (DSSCs). Based on density functional theory (DFT) and time-dependent DFT (TD-DFT) approaches, a series of D-A-π-A-type dye molecules with different auxiliary acceptors were designed. The structures, frontier molecular orbital (FMO), absorption spectra (UV) are investigated theoretically. Key parameters related to short-circuit current density and open-circuit voltage, such as light-harvesting efficiency (LHE), the reorganization energies (λ), the electronic injection-free energy (ΔGinject), and the regeneration driving forces(ΔGreg)., are calculated individually. In addition, intramolecular charge transfer (ICT) properties such as charge transfer distance (DCT) and dipole moment change (μCT) were investigated. Compared with other dyes, A-7 and A-9 dyes show outstanding performance. The purpose of our study is expected to provide a promising way to design possible candidate sensitizers for DSSC.
{"title":"Theoretical study of the photovoltaic properties of dye-sensitized solar cells with novel D-A-π-A-type benzothiazole molecules as auxiliary acceptors","authors":"Hongxv Shi , Yue Liang , Baoming Hou , Yuheng Li , Meiqi Liu , Yuyu Pan , Bing Yang","doi":"10.1016/j.chemphys.2024.112562","DOIUrl":"10.1016/j.chemphys.2024.112562","url":null,"abstract":"<div><div>The design and synthesis of low-cost-efficient sensitizer dyes is the most important approach to extend the application of dye-sensitized solar cells (DSSCs). Based on density functional theory (DFT) and time-dependent DFT (TD-DFT) approaches, a series of D-A-π-A-type dye molecules with different auxiliary acceptors were designed. The structures, frontier molecular orbital (FMO), absorption spectra (UV) are investigated theoretically. Key parameters related to short-circuit current density and open-circuit voltage, such as light-harvesting efficiency (LHE), the reorganization energies (λ), the electronic injection-free energy (ΔG<sub>inject</sub>), and the regeneration driving forces(ΔGreg)., are calculated individually. In addition, intramolecular charge transfer (ICT) properties such as charge transfer distance (D<sub>CT</sub>) and dipole moment change (μ<sub>CT</sub>) were investigated. Compared with other dyes, A-7 and A-9 dyes show outstanding performance. The purpose of our study is expected to provide a promising way to design possible candidate sensitizers for DSSC.</div></div>","PeriodicalId":272,"journal":{"name":"Chemical Physics","volume":"591 ","pages":"Article 112562"},"PeriodicalIF":2.0,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164755","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 : 2024-11-30DOI: 10.1016/j.chemphys.2024.112547
Amrit Pal Singh , Manish Chopra , Niharendu Choudhury
Extensive atomistic molecular dynamics simulation results suggest that probability of counter ion occupying first solvation shell of uranyl ion depends both on its nature and concentration. In general, uranyl-counter ion complexes with pentagonal bi-pyramidal structure with five ligands in the equatorial plane of the linear UO22+ ion are observed. In case of nitrate ion, pure aqua complexes at lower concentrations and mixed mono-nitro aqua complexes are observed at higher concentrations, whereas in case of sulphate and carbonate ions, no pure aqua complexes are observed. The NO3− and SO42− ions act as unidentate, but CO32− acts both as uni- and bi-dentate ligand. In addition, polynuclear uranium complexes with bridging SO42− and CO32− ligands are observed. Relative strength of binding of counter ions with uranyl ion from PMF calculations follows the order CO32− > SO42− > NO3− with the contact pair free energies of about −29.0, −14.0 and −1.1 kcal/mol respectively.
{"title":"Can different counter ions and their concentration modify the structural characteristics of aqueous solutions of uranyl ions? Atomistic insights from molecular dynamics simulations","authors":"Amrit Pal Singh , Manish Chopra , Niharendu Choudhury","doi":"10.1016/j.chemphys.2024.112547","DOIUrl":"10.1016/j.chemphys.2024.112547","url":null,"abstract":"<div><div>Extensive atomistic molecular dynamics simulation results suggest that probability of counter ion occupying first solvation shell of uranyl ion depends both on its nature and concentration. In general, uranyl-counter ion complexes with pentagonal bi-pyramidal structure with five ligands in the equatorial plane of the linear UO<sub>2</sub><sup>2+</sup> ion are observed. In case of nitrate ion, pure aqua complexes at lower concentrations and mixed mono-nitro aqua complexes are observed at higher concentrations, whereas in case of sulphate and carbonate ions, no pure aqua complexes are observed. The NO<sub>3</sub><sup>−</sup> and SO<sub>4</sub><sup>2−</sup> ions act as unidentate, but CO<sub>3</sub><sup>2−</sup> acts both as uni- and bi-dentate ligand. In addition, polynuclear uranium complexes with bridging SO<sub>4</sub><sup>2−</sup> and CO<sub>3</sub><sup>2−</sup> ligands are observed. Relative strength of binding of counter ions with uranyl ion from PMF calculations follows the order CO<sub>3</sub><sup>2−</sup> > SO<sub>4</sub><sup>2−</sup> > NO<sub>3</sub><sup>−</sup> with the contact pair free energies of about −29.0, −14.0 and −1.1 kcal/mol respectively.</div></div>","PeriodicalId":272,"journal":{"name":"Chemical Physics","volume":"591 ","pages":"Article 112547"},"PeriodicalIF":2.0,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164749","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 : 2024-11-30DOI: 10.1016/j.chemphys.2024.112546
Yuxiu Wang , Yuxuan Zhan , Zhong Xie , Cuicui Sun , Chunhua Yang
The adsorptions of H2S and HF molecules on N-confused porphyrin-like graphene composites G-CoNxC4-x (x = 2, 3, and 4) are investigated by first-principles calculations. Herein, the effective physisorption between G-CoNxC4-x substrates and H2S/HF toxic gases is revealed by no significant charge transfer and large adsorption spacing. Meanwhile, the exothermic adsorption effect and the thermodynamic stability of G-CoNxC4-x substrate are explained by the negative adsorption energies and ab initio molecular dynamics, respectively. Evidently, the G-CoN4 shows a remarkable enhancement in the HF sensing performance while G-CoN3C1 and G-CoN2C2 systems act as sharp responsive adsorbing H2S samples, which is confirmed by the demonstrable changes in electronic and magnetic properties, as well as reasonable short recovery time. Our comprehensive work suggests that fabricating N-confounding is an effective strategy for engineering porphyrin-like graphene-based gas sensitivity features and developing on-demand sensor.
{"title":"Investigation of gas-sensitive properties of N-confused porphyrin-like graphene composites: A viewpoint of first principle","authors":"Yuxiu Wang , Yuxuan Zhan , Zhong Xie , Cuicui Sun , Chunhua Yang","doi":"10.1016/j.chemphys.2024.112546","DOIUrl":"10.1016/j.chemphys.2024.112546","url":null,"abstract":"<div><div>The adsorptions of H<sub>2</sub>S and HF molecules on <em>N</em>-confused porphyrin-like graphene composites G-CoN<sub>x</sub>C<sub>4-x</sub> (x = 2, 3, and 4) are investigated by first-principles calculations. Herein, the effective physisorption between G-CoN<sub>x</sub>C<sub>4-x</sub> substrates and H<sub>2</sub>S/HF toxic gases is revealed by no significant charge transfer and large adsorption spacing. Meanwhile, the exothermic adsorption effect and the thermodynamic stability of G-CoN<sub>x</sub>C<sub>4-x</sub> substrate are explained by the negative adsorption energies and ab initio molecular dynamics, respectively. Evidently, the G-CoN<sub>4</sub> shows a remarkable enhancement in the HF sensing performance while G-CoN<sub>3</sub>C<sub>1</sub> and G-CoN<sub>2</sub>C<sub>2</sub> systems act as sharp responsive adsorbing H<sub>2</sub>S samples, which is confirmed by the demonstrable changes in electronic and magnetic properties, as well as reasonable short recovery time. Our comprehensive work suggests that fabricating <em>N</em>-confounding is an effective strategy for engineering porphyrin-like graphene-based gas sensitivity features and developing on-demand sensor.</div></div>","PeriodicalId":272,"journal":{"name":"Chemical Physics","volume":"591 ","pages":"Article 112546"},"PeriodicalIF":2.0,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164757","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}
In this study, spin-polarized density functional theory (DFT) calculations were utilized to explore the oxygen reduction reaction (ORR) on a transition metal anchored to divacancy graphene (TM@dv-graphene). Our findings demonstrate that divacancy graphene serves as an effective substrate for stabilizing single transition metals, thereby facilitating the ORR. We elucidate the mechanisms of ORR by examining the adsorption of O2, OOH, OH, 2OH, and O intermediates, and identifying two competing ORR pathways: the O* and 2OH* mechanisms. Most TM@dv-graphene catalysts predominantly favor the O* mechanism, with Rh and Ir being notable exceptions that preferentially follow the 2OH* mechanism. Moreover, catalysts co-coordinated with B and N atoms significantly enhance the adsorption of key intermediates, thereby improving ORR activity Specifically, the Co-N4, Co-N2B2, Pd-N2B2, and Pt-N2B2 catalysts demonstrate promising ORR activity with lower overpotentials of 0.47, 0.46, 0.58, and 0.46 V, respectively. This work establishes a foundational framework for comprehending the electrochemical mechanisms of ORR, thus facilitating the design of highly efficient single-atom electrocatalysts.
{"title":"Nitrogen and boron coordinating atoms adjust single-atom catalyst anchored on divacancy defect graphene for highly efficient electrochemical oxygen reduction","authors":"Hsin-Tsung Chen , Yu-Ting Chiou , Tzu-Hui Chen , Hui-Lung Chen","doi":"10.1016/j.chemphys.2024.112540","DOIUrl":"10.1016/j.chemphys.2024.112540","url":null,"abstract":"<div><div>In this study, spin-polarized density functional theory (DFT) calculations were utilized to explore the oxygen reduction reaction (ORR) on a transition metal anchored to divacancy graphene (TM@dv-graphene). Our findings demonstrate that divacancy graphene serves as an effective substrate for stabilizing single transition metals, thereby facilitating the ORR. We elucidate the mechanisms of ORR by examining the adsorption of O<sub>2</sub>, OOH, OH, 2OH, and O intermediates, and identifying two competing ORR pathways: the O* and 2OH* mechanisms. Most TM@dv-graphene catalysts predominantly favor the O* mechanism, with Rh and Ir being notable exceptions that preferentially follow the 2OH* mechanism. Moreover, catalysts co-coordinated with B and N atoms significantly enhance the adsorption of key intermediates, thereby improving ORR activity Specifically, the Co-N<sub>4</sub>, Co-N<sub>2</sub>B<sub>2</sub>, Pd-N<sub>2</sub>B<sub>2</sub>, and Pt-N<sub>2</sub>B<sub>2</sub> catalysts demonstrate promising ORR activity with lower overpotentials of 0.47, 0.46, 0.58, and 0.46 V, respectively. This work establishes a foundational framework for comprehending the electrochemical mechanisms of ORR, thus facilitating the design of highly efficient single-atom electrocatalysts.</div></div>","PeriodicalId":272,"journal":{"name":"Chemical Physics","volume":"591 ","pages":"Article 112540"},"PeriodicalIF":2.0,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164118","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}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号