Pub Date : 2025-04-22DOI: 10.1021/acs.jpcc.5c00855
Tarik Ouahrani, A. Esquembre Kučukalić, R. M. Boufatah, Daniel Errandonea
The binding energy of excitons is essential in assessing the suitability of materials for photovoltaic applications. This research employs first-principles calculations based on the GW approximation and the Bethe–Salpeter equation to explore the excitonic characteristics of a Cu2WSe4 monolayer. Our findings support the structural stability of this two-dimensional material and demonstrate a pronounced excitonic response. The computed binding energies for both bright and dark excitons are considerably larger than those that are generally necessary for standard photovoltaic applications. However, examination of exciton amplitude reveals a highly delocalized configuration of electron–hole pairs throughout the crystal, which may alleviate some issues related to elevated binding energies. These results highlight the excitonic properties of Cu2WSe4 and offer valuable insights into its potential for optoelectronic applications.
{"title":"Optical Properties of Single Layer Cu2WSe4 from the Ab Initio Bethe–Salpeter Equation Method","authors":"Tarik Ouahrani, A. Esquembre Kučukalić, R. M. Boufatah, Daniel Errandonea","doi":"10.1021/acs.jpcc.5c00855","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c00855","url":null,"abstract":"The binding energy of excitons is essential in assessing the suitability of materials for photovoltaic applications. This research employs first-principles calculations based on the <i>GW</i> approximation and the Bethe–Salpeter equation to explore the excitonic characteristics of a Cu<sub>2</sub>WSe<sub>4</sub> monolayer. Our findings support the structural stability of this two-dimensional material and demonstrate a pronounced excitonic response. The computed binding energies for both bright and dark excitons are considerably larger than those that are generally necessary for standard photovoltaic applications. However, examination of exciton amplitude reveals a highly delocalized configuration of electron–hole pairs throughout the crystal, which may alleviate some issues related to elevated binding energies. These results highlight the excitonic properties of Cu<sub>2</sub>WSe<sub>4</sub> and offer valuable insights into its potential for optoelectronic applications.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"62 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-22DOI: 10.1021/acs.jpcc.5c01341
Shotaro Yoshida, Susumu Fujii, Masato Yoshiya
Proton-conducting oxides are vital for environmentally friendly electrochemical devices, such as protonic ceramic fuel cells. However, high proton conductivity in oxides has been almost exclusively observed in perovskite structures. In this study, we have performed systematic first-principles calculations to elucidate proton conduction mechanisms in normal spinel compounds AB2O4, which are promising candidates for proton-conducting oxides. Our results reveal that in the spinel structure, protons occupy the octahedral interstices of the oxygen sublattice and diffuse three-dimensionally via a combination of proton rotation and hopping. The hopping energy barrier increases with the volume of the octahedral interstice, whereas the rotation energy barrier depends on the A-site cation displacement during proton migration. Notably, these energy barriers are reversed in A2+B23+O42– and A4+B22+O42– compounds. The magnitudes of these barriers are comparable to those of cubic perovskites, and our analysis suggests that the activation energy of proton diffusion is minimized when the tolerance factors for spinels lie between 0.9 and 1.0. These findings provide design guidelines for the development of proton-conducting spinel oxides.
{"title":"Proton Conduction Mechanisms in Spinel Compounds: A First-Principles Study of Structural and Elemental Effects","authors":"Shotaro Yoshida, Susumu Fujii, Masato Yoshiya","doi":"10.1021/acs.jpcc.5c01341","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c01341","url":null,"abstract":"Proton-conducting oxides are vital for environmentally friendly electrochemical devices, such as protonic ceramic fuel cells. However, high proton conductivity in oxides has been almost exclusively observed in perovskite structures. In this study, we have performed systematic first-principles calculations to elucidate proton conduction mechanisms in normal spinel compounds AB<sub>2</sub>O<sub>4</sub>, which are promising candidates for proton-conducting oxides. Our results reveal that in the spinel structure, protons occupy the octahedral interstices of the oxygen sublattice and diffuse three-dimensionally via a combination of proton rotation and hopping. The hopping energy barrier increases with the volume of the octahedral interstice, whereas the rotation energy barrier depends on the A-site cation displacement during proton migration. Notably, these energy barriers are reversed in A<sup>2+</sup>B<sub>2</sub><sup>3+</sup>O<sub>4</sub><sup>2–</sup> and A<sup>4+</sup>B<sub>2</sub><sup>2+</sup>O<sub>4</sub><sup>2–</sup> compounds. The magnitudes of these barriers are comparable to those of cubic perovskites, and our analysis suggests that the activation energy of proton diffusion is minimized when the tolerance factors for spinels lie between 0.9 and 1.0. These findings provide design guidelines for the development of proton-conducting spinel oxides.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"2 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858238","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-22DOI: 10.1021/acs.jpcc.4c08088
Jin Liu, Xuexian Yang, Liwen Yang, Jianwen Ding
The physical origins of the secondary pyroelectric coefficient in response to temperature, size, and shape have long been a puzzle. Based on the local bond average approach, an analytical equation for the temperature effect of the secondary pyroelectric coefficient of bulk GaN, ZnO, ZrO2, and HfO2, and Janus monolayer MoSSe and CrSeBr is established. It is found that the secondary pyroelectric coefficient is inversely proportional to both cohesive energy and the cube of the Debye temperature. Combining the bond-order-length-strength theory and core–shell structural model, the analytical expressions for the size- and shape-dependent secondary pyroelectric coefficients for GaN nanostructures are derived. The results unveil that the crystal size-induced secondary pyroelectric coefficient rising results from the synergetic effect of the increase in piezoelectric coefficient and the decrease in both Debye temperature and cohesive energy caused by bond order deficiency at the surface layer. The secondary pyroelectric coefficient increases with the decrease in the number of sides for polyhedral nanoparticles and polygonal nanowires or nanotubes due to the rise in surface-to-volume ratio. The size effect of the secondary pyroelectric coefficient for nanotubes is characterized by the wall thickness and does not depend on the radius. The secondary pyroelectric coefficient for nanotubes is always higher than their nanowire counterparts because of their larger surface-to-volume ratios. The current study is anticipated to have implications in the field of nanoscale thermal energy harvesting.
{"title":"Bond Relaxation Insight into Secondary Pyroelectric Coefficient from One- to Three-Dimensional Materials: Temperature-, Size-, and Shape Effects","authors":"Jin Liu, Xuexian Yang, Liwen Yang, Jianwen Ding","doi":"10.1021/acs.jpcc.4c08088","DOIUrl":"https://doi.org/10.1021/acs.jpcc.4c08088","url":null,"abstract":"The physical origins of the secondary pyroelectric coefficient in response to temperature, size, and shape have long been a puzzle. Based on the local bond average approach, an analytical equation for the temperature effect of the secondary pyroelectric coefficient of bulk GaN, ZnO, ZrO<sub>2</sub>, and HfO<sub>2</sub>, and Janus monolayer MoSSe and CrSeBr is established. It is found that the secondary pyroelectric coefficient is inversely proportional to both cohesive energy and the cube of the Debye temperature. Combining the bond-order-length-strength theory and core–shell structural model, the analytical expressions for the size- and shape-dependent secondary pyroelectric coefficients for GaN nanostructures are derived. The results unveil that the crystal size-induced secondary pyroelectric coefficient rising results from the synergetic effect of the increase in piezoelectric coefficient and the decrease in both Debye temperature and cohesive energy caused by bond order deficiency at the surface layer. The secondary pyroelectric coefficient increases with the decrease in the number of sides for polyhedral nanoparticles and polygonal nanowires or nanotubes due to the rise in surface-to-volume ratio. The size effect of the secondary pyroelectric coefficient for nanotubes is characterized by the wall thickness and does not depend on the radius. The secondary pyroelectric coefficient for nanotubes is always higher than their nanowire counterparts because of their larger surface-to-volume ratios. The current study is anticipated to have implications in the field of nanoscale thermal energy harvesting.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"7 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858237","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}
A computational methodology combining classical molecular dynamic simulations and density functional theory calculations is employed to characterize the second harmonic generation (SHG) response of self-assembled monolayers (SAMs) functionalized with azobenzene photochromic units. Chemical substitution of the azobenzene core is explored to investigate how the nature of the substituent influences the morphology and nonlinear optical (NLO) properties of the SAMs. The interfacial NLO responses are computed, accounting for the effect of structural fluctuations and steric interactions of individual azobenzene units, as well as electrostatic intermolecular interactions. It turns out that the para functionalization of the terminal phenyl of the azobenzene core with an electron-acceptor group is promising for applications, since it enhances the NLO contrast perpendicular to the surface with respect to the nonsubstituted system, while maintaining well-separated SHG signal ranges for the two E and Z isomeric forms, making them easily distinguishable for polarization-resolved SHG measurements.
{"title":"Second Harmonic Response of Azobenzene Self-Assembled Monolayers: the Effect of Push/Pull Substitution","authors":"Angela Dellai, Luca Muccioli, Frédéric Castet, Claire Tonnelé","doi":"10.1021/acs.jpcc.5c01204","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c01204","url":null,"abstract":"A computational methodology combining classical molecular dynamic simulations and density functional theory calculations is employed to characterize the second harmonic generation (SHG) response of self-assembled monolayers (SAMs) functionalized with azobenzene photochromic units. Chemical substitution of the azobenzene core is explored to investigate how the nature of the substituent influences the morphology and nonlinear optical (NLO) properties of the SAMs. The interfacial NLO responses are computed, accounting for the effect of structural fluctuations and steric interactions of individual azobenzene units, as well as electrostatic intermolecular interactions. It turns out that the para functionalization of the terminal phenyl of the azobenzene core with an electron-acceptor group is promising for applications, since it enhances the NLO contrast perpendicular to the surface with respect to the nonsubstituted system, while maintaining well-separated SHG signal ranges for the two E and Z isomeric forms, making them easily distinguishable for polarization-resolved SHG measurements.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"91 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143862142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-22DOI: 10.1021/acs.jpcc.5c01283
Qingying Yao, Wenhua Feng, Yun Yang, Yuting Miao, Jinwen Zhang, Li Zhang, Yuanhang Ren, Lin Ye, Xueying Chen, Kai Xiong, Shixi Liu, Bin Yue, Heyong He
ZnO is an important component of the Cu/ZnO catalyst for catalyzing the carbon dioxide hydrogenation, which is used not only as a support to stabilize other metal species loaded on its surface but also its surface oxygen vacancies provide adsorption and catalytic active sites for the reactants as well as intermediates. In order to investigate the generation and nature of surface oxygen vacancies on ZnO crystalline surfaces and the activation of CO2 and H2, ZnO nanorods with exposed {100} surfaces were treated at different temperatures under vacuum conditions. The surface oxygen vacancies were characterized by 31P MAS NMR with trimethylphosphine (TMP) as the probe molecule, 1H–31P CP/MAS NMR, and pyridine adsorption infrared spectroscopies. Based on the characterization results, the adsorption model of the probe molecule TMP on the surface of ZnO was established, and the density of the oxygen vacancies on the surface was quantitatively measured. The concentration of surface oxygen vacancies reached the maximum value when the treatment temperature was 350 °C under vacuum conditions. On such surface, the activation mechanism of CO2 and H2 was proposed based on the surface structure of ZnO nanorods with exposed {100} surfaces before and after the adsorption and activation of H2 as well as the relevant generated intermediates on the surface during CO2 hydrogenation characterized by 1H, 31P, and 13C MAS NMR techniques.
{"title":"MAS NMR Studies on the Formation and Catalytic Activity of Oxygen Vacancy on the ZnO {100} Surface","authors":"Qingying Yao, Wenhua Feng, Yun Yang, Yuting Miao, Jinwen Zhang, Li Zhang, Yuanhang Ren, Lin Ye, Xueying Chen, Kai Xiong, Shixi Liu, Bin Yue, Heyong He","doi":"10.1021/acs.jpcc.5c01283","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c01283","url":null,"abstract":"ZnO is an important component of the Cu/ZnO catalyst for catalyzing the carbon dioxide hydrogenation, which is used not only as a support to stabilize other metal species loaded on its surface but also its surface oxygen vacancies provide adsorption and catalytic active sites for the reactants as well as intermediates. In order to investigate the generation and nature of surface oxygen vacancies on ZnO crystalline surfaces and the activation of CO<sub>2</sub> and H<sub>2</sub>, ZnO nanorods with exposed {100} surfaces were treated at different temperatures under vacuum conditions. The surface oxygen vacancies were characterized by <sup>31</sup>P MAS NMR with trimethylphosphine (TMP) as the probe molecule, <sup>1</sup>H–<sup>31</sup>P CP/MAS NMR, and pyridine adsorption infrared spectroscopies. Based on the characterization results, the adsorption model of the probe molecule TMP on the surface of ZnO was established, and the density of the oxygen vacancies on the surface was quantitatively measured. The concentration of surface oxygen vacancies reached the maximum value when the treatment temperature was 350 °C under vacuum conditions. On such surface, the activation mechanism of CO<sub>2</sub> and H<sub>2</sub> was proposed based on the surface structure of ZnO nanorods with exposed {100} surfaces before and after the adsorption and activation of H<sub>2</sub> as well as the relevant generated intermediates on the surface during CO<sub>2</sub> hydrogenation characterized by <sup>1</sup>H, <sup>31</sup>P, and <sup>13</sup>C MAS NMR techniques.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"28 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143862143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-22DOI: 10.1021/acs.jpcc.4c08621
Yves A. Mantz, Yinkai Lei, Wissam A. Saidi, Harry W. Abernathy, Youhai Wen
The coarsening of the Ni particles in the hydrogen electrode of solid oxide cells (SOCs) is an important degradation mechanism. In this paper, density-functional theory and kinetic Monte Carlo methods are used to explore our recent hypothesis that the surface diffusion of NiH may cause faster Ni coarsening in electrolysis cell mode under an overpotential. Using both methods, the diffusion constant or diffusivity of NiH on Ni (111) is determined as the product of the surface coverage and single-molecule diffusivity for the first time considering all possible diffusion paths. It is then determined versus overpotential at the triple-phase boundary of the hydrogen electrode assuming a typical operating temperature of the SOC. Under a significant overpotential, the diffusivity of NiH is found to be sufficiently large to support the above hypothesis that NiH may promote Ni coarsening. However, based on the adsorption configurations identified, the dissociation and reformation of NiH on Ni (111) could occur. Thus, more work is needed to develop a model of Ni coarsening considering both molecular and dissociated forms of NiH.
{"title":"Toward a Better Understanding of Ni Coarsening in Solid Oxide Cells: NiH on Ni (111) Examined Using a Combined Theoretical Approach","authors":"Yves A. Mantz, Yinkai Lei, Wissam A. Saidi, Harry W. Abernathy, Youhai Wen","doi":"10.1021/acs.jpcc.4c08621","DOIUrl":"https://doi.org/10.1021/acs.jpcc.4c08621","url":null,"abstract":"The coarsening of the Ni particles in the hydrogen electrode of solid oxide cells (SOCs) is an important degradation mechanism. In this paper, density-functional theory and kinetic Monte Carlo methods are used to explore our recent hypothesis that the surface diffusion of NiH may cause faster Ni coarsening in electrolysis cell mode under an overpotential. Using both methods, the diffusion constant or diffusivity of NiH on Ni (111) is determined as the product of the surface coverage and single-molecule diffusivity for the first time considering all possible diffusion paths. It is then determined versus overpotential at the triple-phase boundary of the hydrogen electrode assuming a typical operating temperature of the SOC. Under a significant overpotential, the diffusivity of NiH is found to be sufficiently large to support the above hypothesis that NiH may promote Ni coarsening. However, based on the adsorption configurations identified, the dissociation and reformation of NiH on Ni (111) could occur. Thus, more work is needed to develop a model of Ni coarsening considering both molecular and dissociated forms of NiH.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"4 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143862317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-22DOI: 10.1021/acs.jpcc.5c00161
Alison Arissa, Thomas Rose, Noémi Leick, Stefan Grimme, Justin C. Johnson, Jenny V. Lockard
Porphyrin-based metal–organic frameworks (MOFs) offer a unique platform for building porous donor–acceptor networks that exhibit long-lived charge separation and transport upon incorporation of electron acceptor guest species. Here, porphyrin-based MOFs, PCN-222(H2) and PCN-222(Zn), synthesized as nanoparticle suspensions, are successfully infiltrated with fullerene acceptor molecules, C60 or PC61BM, in both polar and nonpolar solvent environments. The location and relative binding strength of these guest species are evaluated through a combination of N2 physisorption measurements, photoluminescence quenching, and UV–vis absorption titration experiments. Semiempirical tight binding calculations are used to screen potential locations of the fullerene guest within the MOF pores, and hybrid density functional theory (DFT)-computed interaction energies confirm the energetically favorable positions. The fundamental photophysics of these donor–acceptor host–guest combinations are probed using ultrafast transient absorption spectroscopy. Sub-picosecond electron transfer involving initial exciplex population is observed, with slow charge recombination lifetimes on the order of τ ∼1 ns for all systems in both dimethylformamide and 1,4-dioxane. Charge recombination occurs through population of fullerene and/or framework porphyrin triplet states depending on the porphyrin metalation status. The photophysics of the fullerene-loaded MOFs are discussed in the context of relevant porphyrin–fullerene donor–acceptor molecules to highlight the unique role of the framework environment in dictating photoinduced electron transfer and decay pathways.
{"title":"Charge Transfer and Recombination Pathways through Fullerene Guests in Porphyrin-Based MOFs","authors":"Alison Arissa, Thomas Rose, Noémi Leick, Stefan Grimme, Justin C. Johnson, Jenny V. Lockard","doi":"10.1021/acs.jpcc.5c00161","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c00161","url":null,"abstract":"Porphyrin-based metal–organic frameworks (MOFs) offer a unique platform for building porous donor–acceptor networks that exhibit long-lived charge separation and transport upon incorporation of electron acceptor guest species. Here, porphyrin-based MOFs, PCN-222(H<sub>2</sub>) and PCN-222(Zn), synthesized as nanoparticle suspensions, are successfully infiltrated with fullerene acceptor molecules, C<sub>60</sub> or PC<sub>61</sub>BM, in both polar and nonpolar solvent environments. The location and relative binding strength of these guest species are evaluated through a combination of N<sub>2</sub> physisorption measurements, photoluminescence quenching, and UV–vis absorption titration experiments. Semiempirical tight binding calculations are used to screen potential locations of the fullerene guest within the MOF pores, and hybrid density functional theory (DFT)-computed interaction energies confirm the energetically favorable positions. The fundamental photophysics of these donor–acceptor host–guest combinations are probed using ultrafast transient absorption spectroscopy. Sub-picosecond electron transfer involving initial exciplex population is observed, with slow charge recombination lifetimes on the order of τ ∼1 ns for all systems in both dimethylformamide and 1,4-dioxane. Charge recombination occurs through population of fullerene and/or framework porphyrin triplet states depending on the porphyrin metalation status. The photophysics of the fullerene-loaded MOFs are discussed in the context of relevant porphyrin–fullerene donor–acceptor molecules to highlight the unique role of the framework environment in dictating photoinduced electron transfer and decay pathways.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"37 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143862318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-22DOI: 10.1021/acs.jpcc.4c08652
Yongjie Jiang, Hui Guo, Feng Cheng, Zhao-Xu Chen
Conversion of CO2 to ethanol is a potential method for carbon capture and utilization. Among various catalysts for this reaction, Pd2Cu is found to have high activity and selectivity. In this paper, we investigated the reaction mechanism using mean-field microkinetic modeling (MF-MKM) and kinetic Monte Carlo (kMC) simulations. To overcome the stiffness problem caused by the significant difference in time scales of different events in kMC simulation, we employed the ads-kMC algorithm proposed in our previous work, in which the adsorption/desorption/reaction rate constants were reduced under certain requirements and the diffusion process was treated by redistributing surface species each time an event occurs. Both methods show similar surface coverage, i.e., the surface is fully covered by H and CO and exhibits high selectivity for ethanol. This study also compares the effect of species diffusion rates on the kMC simulations. The results show that the diffusion rate changes the reaction mechanism and coverage, and under slow diffusion case the kMC predicted selectivity is higher than that under fast diffusion. The present study sheds light on the mechanism of CO2 hydrogenation to ethanol on Pd2Cu catalyst, deepens the understanding of kMC and MF-MKM simulations, and examines the influence of species diffusion on reaction kinetics.
将二氧化碳转化为乙醇是一种潜在的碳捕获和利用方法。在该反应的各种催化剂中，Pd2Cu 被认为具有较高的活性和选择性。本文采用均场微动力学建模（MF-MKM）和动力学蒙特卡罗（kMC）模拟研究了反应机理。为了克服 kMC 模拟中不同事件的时间尺度差异较大所导致的僵化问题，我们采用了之前工作中提出的 ads-kMC 算法，即在一定要求下降低吸附/解吸/反应速率常数，并在每次事件发生时通过重新分配表面物种来处理扩散过程。两种方法都显示出相似的表面覆盖率，即表面被 H 和 CO 完全覆盖，并对乙醇表现出高选择性。本研究还比较了物种扩散率对 kMC 模拟的影响。结果表明，扩散速率会改变反应机制和覆盖率，在慢扩散情况下，kMC 预测的选择性高于快扩散情况下的选择性。本研究揭示了 Pd2Cu 催化剂上 CO2 加氢制乙醇的机理，加深了对 kMC 和 MF-MKM 模拟的理解，并考察了物种扩散对反应动力学的影响。
{"title":"Kinetic Simulations of CO2 Hydrogenation to Ethanol on Pd2Cu (110)","authors":"Yongjie Jiang, Hui Guo, Feng Cheng, Zhao-Xu Chen","doi":"10.1021/acs.jpcc.4c08652","DOIUrl":"https://doi.org/10.1021/acs.jpcc.4c08652","url":null,"abstract":"Conversion of CO<sub>2</sub> to ethanol is a potential method for carbon capture and utilization. Among various catalysts for this reaction, Pd<sub>2</sub>Cu is found to have high activity and selectivity. In this paper, we investigated the reaction mechanism using mean-field microkinetic modeling (MF-MKM) and kinetic Monte Carlo (kMC) simulations. To overcome the stiffness problem caused by the significant difference in time scales of different events in kMC simulation, we employed the ads-kMC algorithm proposed in our previous work, in which the adsorption/desorption/reaction rate constants were reduced under certain requirements and the diffusion process was treated by redistributing surface species each time an event occurs. Both methods show similar surface coverage, i.e., the surface is fully covered by H and CO and exhibits high selectivity for ethanol. This study also compares the effect of species diffusion rates on the kMC simulations. The results show that the diffusion rate changes the reaction mechanism and coverage, and under slow diffusion case the kMC predicted selectivity is higher than that under fast diffusion. The present study sheds light on the mechanism of CO<sub>2</sub> hydrogenation to ethanol on Pd<sub>2</sub>Cu catalyst, deepens the understanding of kMC and MF-MKM simulations, and examines the influence of species diffusion on reaction kinetics.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"43 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858234","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}
Owing to the promising optoelectronic and thermoelectric properties of two-dimensional (2D) group III–VI materials (MXs), their nanoribbons (NRs) have attracted notable attention as an emerging class of quasi-one-dimensional (quasi-1D) nanostructures. Due to the fact that the most stable 2D monolayer polymorph of MXs is the 1H phase, to date, existing studies in the literature have predominantly focused on the NRs formed from 1H phase MXs. Nevertheless, NRs of the 1T phase have received little to no attention. Employing ab initio simulations based on density functional theory, we systematically compared the thermodynamic stability of hydrogen-passivated and unpassivated 1T and 1H ZNRs of GaS, GaSe, and InSe. Our results reveal that nonpolar 1T phase MX ZNRs are thermodynamically more favorable than polar 1H MX ZNRs at widths up to 34 nm, a range that is realizable through contemporary experimental fabrication techniques. Furthermore, unlike metallic 1H ZNRs, 1T ZNRs remain semiconductors and retain Mexican-hat-shaped top valence bands. Complementarily, hydrogenation energies of 1T InSe ZNRs are positive, and due to the edge-localized states, the 1T unpassivated ZNRs possess nearly flat top valence bands. Our findings serve as a compass for subsequent synthesis pathways of group III–VI NRs.
{"title":"Thermodynamic Favorability of the 1T Phase over the 1H Phase in Group III Metal Monochalcogenide Zigzag Nanoribbons","authors":"Emin Aliyev, Arash Mobaraki, Hâldun Sevinçli, Seymur Jahangirov","doi":"10.1021/acs.jpcc.5c00765","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c00765","url":null,"abstract":"Owing to the promising optoelectronic and thermoelectric properties of two-dimensional (2D) group III–VI materials (MXs), their nanoribbons (NRs) have attracted notable attention as an emerging class of quasi-one-dimensional (quasi-1D) nanostructures. Due to the fact that the most stable 2D monolayer polymorph of MXs is the 1H phase, to date, existing studies in the literature have predominantly focused on the NRs formed from 1H phase MXs. Nevertheless, NRs of the 1T phase have received little to no attention. Employing ab initio simulations based on density functional theory, we systematically compared the thermodynamic stability of hydrogen-passivated and unpassivated 1T and 1H ZNRs of GaS, GaSe, and InSe. Our results reveal that nonpolar 1T phase MX ZNRs are thermodynamically more favorable than polar 1H MX ZNRs at widths up to 34 nm, a range that is realizable through contemporary experimental fabrication techniques. Furthermore, unlike metallic 1H ZNRs, 1T ZNRs remain semiconductors and retain Mexican-hat-shaped top valence bands. Complementarily, hydrogenation energies of 1T InSe ZNRs are positive, and due to the edge-localized states, the 1T unpassivated ZNRs possess nearly flat top valence bands. Our findings serve as a compass for subsequent synthesis pathways of group III–VI NRs.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"12 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-21DOI: 10.1021/acs.jpcc.5c00874
Eui-Cheol Shin, Youngho Kang, Sang Ho Jeon
This study presents a fundamental investigation into nitrogen complex in group-III nitrides using first-principles calculations, revealing the thermodynamic mechanisms governing vacancy cluster formation under different charge states. We find that nitrogen complexes drive agglomeration of vacancies in (Al, Ga)N through hole compensation and structural reconfiguration, while in n-type conditions and antibonding interactions introduce instability. InN exhibits a distinct behavior, maintaining robust VCs across doping conditions due to the unique role of metal–metal bonding, particularly indium trimer states, which suppress defect-driven instabilities. Our results highlight the intricate interplay between charge states, nitrogen complex, and bonding nature in shaping defect stability, offering new insights into defect engineering for nitride-based semiconductor applications.
{"title":"Thermodynamic Role of Nitrogen Complex in Vacancy Cluster of Group-III Nitrides","authors":"Eui-Cheol Shin, Youngho Kang, Sang Ho Jeon","doi":"10.1021/acs.jpcc.5c00874","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c00874","url":null,"abstract":"This study presents a fundamental investigation into nitrogen complex in group-III nitrides using first-principles calculations, revealing the thermodynamic mechanisms governing vacancy cluster formation under different charge states. We find that nitrogen complexes drive agglomeration of vacancies in (Al, Ga)N through hole compensation and structural reconfiguration, while in <i>n</i>-type conditions and antibonding interactions introduce instability. InN exhibits a distinct behavior, maintaining robust VCs across doping conditions due to the unique role of metal–metal bonding, particularly indium trimer states, which suppress defect-driven instabilities. Our results highlight the intricate interplay between charge states, nitrogen complex, and bonding nature in shaping defect stability, offering new insights into defect engineering for nitride-based semiconductor applications.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"28 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143853386","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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