Molybdenum carbide (MoC) is a promising candidate for substituting expensive platinum-group metals in many applications owing to its low cost and excellent properties; therefore, a comprehensive understanding of its carrier dynamics is demanded for advancing the synthesis strategy and implementation of MoC. In this work, the carrier relaxation in MoC nanosheets is investigated by combining femtosecond transient reflection spectroscopy with first-principles calculations. The measured processes of electron–electron, electron–phonon, and phonon–phonon scattering show significantly longer lifetimes compared with those of other transition-metal carbides. Based on the analysis of calculated phonon dispersion, the nanosecond-carrier lifetime is consistent with the restricted phonon decay pathways, which is induced by the large mass difference between Mo and C atoms. The observed slow carrier cooling rate in our study offers a straightforward approach for effectively utilizing hot carriers, which is expected to improve the performance of photothermal and photovoltaic devices.
{"title":"Dynamics of Long-Lived Carriers in Molybdenum Carbide Nanosheets","authors":"Xiangyu Zhu,Zhong Wang,Tao Li,Xi Wang,Zheng Zhang,Chunlong Hu,Kaifu Huo,Wenxi Liang","doi":"10.1021/acs.jpcc.6c04911","DOIUrl":"https://doi.org/10.1021/acs.jpcc.6c04911","url":null,"abstract":"Molybdenum carbide (MoC) is a promising candidate for substituting expensive platinum-group metals in many applications owing to its low cost and excellent properties; therefore, a comprehensive understanding of its carrier dynamics is demanded for advancing the synthesis strategy and implementation of MoC. In this work, the carrier relaxation in MoC nanosheets is investigated by combining femtosecond transient reflection spectroscopy with first-principles calculations. The measured processes of electron–electron, electron–phonon, and phonon–phonon scattering show significantly longer lifetimes compared with those of other transition-metal carbides. Based on the analysis of calculated phonon dispersion, the nanosecond-carrier lifetime is consistent with the restricted phonon decay pathways, which is induced by the large mass difference between Mo and C atoms. The observed slow carrier cooling rate in our study offers a straightforward approach for effectively utilizing hot carriers, which is expected to improve the performance of photothermal and photovoltaic devices.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"1 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-20DOI: 10.1021/acs.jpcc.6c01336
Yasir Mahmood,Daniel Wines,Viviana Dovale-Farelo,Kamal Choudhary,Lucas M. Hale
Silicon nanowires (Si NWs) have emerged as promising candidates for next-generation nanoelectronic devices due to their tunable electronic properties, and compatibility with aggressive scaling requirements. The integration of strain further enhances their performance by modulating carrier mobility, band structure, and transport behavior without altering material chemistry. Within the NW, the silicon–silicon dioxide (Si–SiO2) interface serves as a critical region where strain redistribution and suboxide bonding collectively influence the mechanical and electronic response. Here, we combine reactive force field molecular dynamics and first-principles calculations to investigate how oxidation-induced interfacial structure and crystallographic facet orientation govern strain-dependent bond evolution and facet-dependent strain response of electronic properties in oxidized Si NWs. Simulated dry thermal oxidation generates chemically realistic Si–SiO2 interfaces, enabling direct characterization of bond order redistribution and stress gradient development across the interface under tensile strain. Interfacial Si–Si bonds exhibit elongation and reduced bond order associated with partial oxidation states, leading to localized stress concentration and preferential bond rupture. Complementary density functional theory calculations on facet-specific models reveal that orientation-dependent interfacial bonding modulates facet-dependent strain response of electronic properties. Together, these results establish a direct coupling between interfacial suboxide chemistry, mechanical deformation, and electronic structure, providing atomistic insight into strain-modulated behavior at oxidized silicon interfaces in faceted NWs.
{"title":"Strain-Induced Interfacial Bond Evolution and Facet-Dependent Strain Response of Electronic Properties in Oxidized Silicon Nanowires","authors":"Yasir Mahmood,Daniel Wines,Viviana Dovale-Farelo,Kamal Choudhary,Lucas M. Hale","doi":"10.1021/acs.jpcc.6c01336","DOIUrl":"https://doi.org/10.1021/acs.jpcc.6c01336","url":null,"abstract":"Silicon nanowires (Si NWs) have emerged as promising candidates for next-generation nanoelectronic devices due to their tunable electronic properties, and compatibility with aggressive scaling requirements. The integration of strain further enhances their performance by modulating carrier mobility, band structure, and transport behavior without altering material chemistry. Within the NW, the silicon–silicon dioxide (Si–SiO2) interface serves as a critical region where strain redistribution and suboxide bonding collectively influence the mechanical and electronic response. Here, we combine reactive force field molecular dynamics and first-principles calculations to investigate how oxidation-induced interfacial structure and crystallographic facet orientation govern strain-dependent bond evolution and facet-dependent strain response of electronic properties in oxidized Si NWs. Simulated dry thermal oxidation generates chemically realistic Si–SiO2 interfaces, enabling direct characterization of bond order redistribution and stress gradient development across the interface under tensile strain. Interfacial Si–Si bonds exhibit elongation and reduced bond order associated with partial oxidation states, leading to localized stress concentration and preferential bond rupture. Complementary density functional theory calculations on facet-specific models reveal that orientation-dependent interfacial bonding modulates facet-dependent strain response of electronic properties. Together, these results establish a direct coupling between interfacial suboxide chemistry, mechanical deformation, and electronic structure, providing atomistic insight into strain-modulated behavior at oxidized silicon interfaces in faceted NWs.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"12 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-20DOI: 10.1021/acs.jpcc.6c01812
Wenli Bao,Weiwei Zhang,Gui-Rong Zhang,Junfeng Rong,Qiugen Zhang,Donghai Mei
Anion exchange membrane (AEM)-based water electrolysis represents a promising pathway for sustainable hydrogen production, leveraging nonprecious metal catalysts. A comprehensive understanding of hydroxide ion (OH–) transport mechanisms within AEMs is crucial to achieving high-performance electrolysis. However, the influence of an electric field on OH– diffusion in aqueous AEMs remains inadequately explored. This study employs reactive force field (ReaxFF) molecular dynamics (MD) simulations to investigate OH– diffusion through four distinct mechanisms: Free-Vehicular, Free-Grotthuss, Associate-Vehicular, and Associate-Grotthuss. Three poly(biphenyl alkylene) (PBPA) AEMs with varying hydration levels and hydrophilicity were analyzed under conditions with and without an applied electric field. Results indicate that the Associate-Grotthuss mechanism predominantly governs OH– diffusion across all three AEMs. Higher hydration levels enhance OH– diffusion rates, while the application of an electric field significantly increases the total diffusion coefficient of OH–. Microstructural analysis further reveals that AEMs with higher hydration levels and greater hydrophilicity promote OH– diffusion by preserving water channel continuity and pore width. Additionally, the electric field improves the orientation order of water molecules, further facilitating OH– transport. These findings provide valuable insights into the enhancement of hydroxide ion diffusion via applied electric fields and offer theoretical guidance for designing high-conductivity AEMs to advance water electrolysis technology.
{"title":"Effects of an Electric Field on Hydroxide Diffusion in Aqueous Anion Exchange Membranes","authors":"Wenli Bao,Weiwei Zhang,Gui-Rong Zhang,Junfeng Rong,Qiugen Zhang,Donghai Mei","doi":"10.1021/acs.jpcc.6c01812","DOIUrl":"https://doi.org/10.1021/acs.jpcc.6c01812","url":null,"abstract":"Anion exchange membrane (AEM)-based water electrolysis represents a promising pathway for sustainable hydrogen production, leveraging nonprecious metal catalysts. A comprehensive understanding of hydroxide ion (OH–) transport mechanisms within AEMs is crucial to achieving high-performance electrolysis. However, the influence of an electric field on OH– diffusion in aqueous AEMs remains inadequately explored. This study employs reactive force field (ReaxFF) molecular dynamics (MD) simulations to investigate OH– diffusion through four distinct mechanisms: Free-Vehicular, Free-Grotthuss, Associate-Vehicular, and Associate-Grotthuss. Three poly(biphenyl alkylene) (PBPA) AEMs with varying hydration levels and hydrophilicity were analyzed under conditions with and without an applied electric field. Results indicate that the Associate-Grotthuss mechanism predominantly governs OH– diffusion across all three AEMs. Higher hydration levels enhance OH– diffusion rates, while the application of an electric field significantly increases the total diffusion coefficient of OH–. Microstructural analysis further reveals that AEMs with higher hydration levels and greater hydrophilicity promote OH– diffusion by preserving water channel continuity and pore width. Additionally, the electric field improves the orientation order of water molecules, further facilitating OH– transport. These findings provide valuable insights into the enhancement of hydroxide ion diffusion via applied electric fields and offer theoretical guidance for designing high-conductivity AEMs to advance water electrolysis technology.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"33 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149221726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-20DOI: 10.1021/acs.jpcc.6c05282
Michael M. J. Treacy
Al placement in aluminosilicate zeolite frameworks, treated as a Löwenstein-constrained “framework gas” of Si and Al on the T-site network, is investigated using Wang–Landau sampling. For composition Si1–fAlf (0 ≤ f ≤ 1/2), bipartite-graph frameworks with all even-membered rings, such as faujasite (FAU), undergo two structural phase transitions as f increases. At fFAUcp ≳ 0.21 (Si:Al ≈ 3.8), a graph-theoretic analog of critical opalescence emerges, in which ordered Al clusters metastably compete between the antiphase bipartite subgraphs. At fFAUc ≳ 0.31 (Si:Al ≈ 2.2), the system undergoes an order–disorder transition, where one subgraph dominates, analogous to an Ising ferromagnet crossing Tc. Ordering completes at fFAUmax = 1/2 (Si:Al = 1) in one of the two bipartite states. Nonbipartite frameworks with moderate odd-ring densities (e.g., MFI) frustrate subgraph ordering but exhibit the same qualitative behavior, with ordering competing among the symmetry-related saturated states at fmax < 1/2. Frameworks dominated by odd rings (e.g., MTN, 94% 5-rings) are too frustrated to sustain either transition. Above fc, Al ordering in bipartite frameworks is combinatorially inevitable, dictated by graph topology under Löwenstein’s rule alone, independent of framework energetics or synthesis conditions. Random dense packing of Al in FAU already reaches f ≈ 0.36 ± 0.05, well within the ordered regime, and exhibits substantial medium-range order despite the randomness of Al insertions.
{"title":"Configurational Order–Disorder in Aluminosilicate Zeolite Frameworks","authors":"Michael M. J. Treacy","doi":"10.1021/acs.jpcc.6c05282","DOIUrl":"https://doi.org/10.1021/acs.jpcc.6c05282","url":null,"abstract":"Al placement in aluminosilicate zeolite frameworks, treated as a Löwenstein-constrained “framework gas” of Si and Al on the T-site network, is investigated using Wang–Landau sampling. For composition Si1–fAlf (0 ≤ f ≤ 1/2), bipartite-graph frameworks with all even-membered rings, such as faujasite (FAU), undergo two structural phase transitions as f increases. At fFAUcp ≳ 0.21 (Si:Al ≈ 3.8), a graph-theoretic analog of critical opalescence emerges, in which ordered Al clusters metastably compete between the antiphase bipartite subgraphs. At fFAUc ≳ 0.31 (Si:Al ≈ 2.2), the system undergoes an order–disorder transition, where one subgraph dominates, analogous to an Ising ferromagnet crossing Tc. Ordering completes at fFAUmax = 1/2 (Si:Al = 1) in one of the two bipartite states. Nonbipartite frameworks with moderate odd-ring densities (e.g., MFI) frustrate subgraph ordering but exhibit the same qualitative behavior, with ordering competing among the symmetry-related saturated states at fmax < 1/2. Frameworks dominated by odd rings (e.g., MTN, 94% 5-rings) are too frustrated to sustain either transition. Above fc, Al ordering in bipartite frameworks is combinatorially inevitable, dictated by graph topology under Löwenstein’s rule alone, independent of framework energetics or synthesis conditions. Random dense packing of Al in FAU already reaches f ≈ 0.36 ± 0.05, well within the ordered regime, and exhibits substantial medium-range order despite the randomness of Al insertions.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"33 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149221725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-19DOI: 10.1021/acs.jpcc.6c04298
Atsushi Sugita,Kazuki Kuroyanagi,Masayoshi Kamiya,Kohei Sato
Nonlinear plasmonic nanostructures provide nanoscale optical-field enhancement, but their second-harmonic generation (SHG) efficiencies are often limited by the surface-confined nonlinearity of metals. Here, we overcome this limitation by hybridizing triangular Au nanoprisms with a poled nonlinear optical (NLO) polymer. The SHG conversion efficiency of the hybrid structure is approximately 500 times larger than that of the PMMA-coated Au nanoprism reference under LSP resonance conditions. Wavelength- and thickness-dependent measurements indicate that the enhanced response is consistent with near-field-mediated activation of nonlinear polarization in the poled NLO polymer, with an additional contribution that is consistent with chromophore-resonance-assisted enhancement. Finite-difference time-domain simulations combined with an effective nonlinear susceptibility analysis support a mechanistic model in which the near-field component normal to the upper Au surface can couple efficiently to the large χzzz(2) response of the poled polymer, whereas destructive interference suppresses the far-field contribution from the PMMA-coated Au nanoprism reference. These results establish NLO-polymer/plasmonic hybrids as a versatile platform for enhancing second-order nonlinear responses in metasurfaces.
{"title":"Interfacial Near-Field Activation of Poled Nonlinear Optical Polymers for Second-Harmonic Generation in Gold Nanoprism Hybrids","authors":"Atsushi Sugita,Kazuki Kuroyanagi,Masayoshi Kamiya,Kohei Sato","doi":"10.1021/acs.jpcc.6c04298","DOIUrl":"https://doi.org/10.1021/acs.jpcc.6c04298","url":null,"abstract":"Nonlinear plasmonic nanostructures provide nanoscale optical-field enhancement, but their second-harmonic generation (SHG) efficiencies are often limited by the surface-confined nonlinearity of metals. Here, we overcome this limitation by hybridizing triangular Au nanoprisms with a poled nonlinear optical (NLO) polymer. The SHG conversion efficiency of the hybrid structure is approximately 500 times larger than that of the PMMA-coated Au nanoprism reference under LSP resonance conditions. Wavelength- and thickness-dependent measurements indicate that the enhanced response is consistent with near-field-mediated activation of nonlinear polarization in the poled NLO polymer, with an additional contribution that is consistent with chromophore-resonance-assisted enhancement. Finite-difference time-domain simulations combined with an effective nonlinear susceptibility analysis support a mechanistic model in which the near-field component normal to the upper Au surface can couple efficiently to the large χzzz(2) response of the poled polymer, whereas destructive interference suppresses the far-field contribution from the PMMA-coated Au nanoprism reference. These results establish NLO-polymer/plasmonic hybrids as a versatile platform for enhancing second-order nonlinear responses in metasurfaces.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"42 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2026-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218903","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}
Developing cost-effective, methanol-tolerant oxygen reduction reaction (ORR) electrocatalysts is critical for alkaline fuel cells and metal–air batteries. This study presents the synthesis of CoTiO3 and Co1–xNixTiO3 (x = 0.1 and 0.2) ilmenite oxides via a sol–gel method and thoroughly examines the influence of Ni substitution in CoTiO3 on its ORR performance. XRD, FTIR, Raman, and XPS analyses confirmed the formation of the ilmenite CoTiO3 framework, successful Ni incorporation, and Ni-induced modulation of the metal–oxygen environment. TEM and FE-SEM analyses revealed nearly spherical nanoparticles, while EDAX verified the expected constituent elements. BET analysis showed that Co0.9Ni0.1TiO3 possessed the highest surface area and pore volume, supporting improved active-site accessibility. Electrocatalytic ORR studies in O2-saturated 1 M KOH demonstrated that Co0.9Ni0.1TiO3 exhibited the best ORR activity among the investigated oxides, with higher cathodic current density, lower charge-transfer resistance, lower Tafel slope, higher exchange current density, increased ECSA, and an apparent near-four-electron ORR pathway, comparable to Pt/C. Co0.9Ni0.1TiO3 also showed excellent methanol tolerance, retaining 84.36% current after 10,000 s in 1 M KOH containing 1 M methanol and 89.98% after 20,000 s in methanol-free 1 M KOH, highlighting its potential as a cost-effective ORR electrocatalyst.
开发高性价比、耐甲醇氧还原反应（ORR）电催化剂对碱性燃料电池和金属-空气电池至关重要。本研究采用溶胶-凝胶法合成CoTiO3和Co1-xNixTiO3 （x = 0.1和0.2）钛铁矿氧化物，并深入研究了CoTiO3中Ni取代对其ORR性能的影响。XRD， FTIR， Raman和XPS分析证实了钛铁矿CoTiO3框架的形成，成功的Ni掺入，以及Ni诱导的金属氧环境的调制。TEM和FE-SEM分析显示纳米颗粒接近球形，EDAX验证了预期的组成元素。BET分析表明，Co0.9Ni0.1TiO3具有最高的比表面积和孔隙体积，支持活性位点可达性的提高。在o2饱和的1 M KOH条件下进行的电催化ORR研究表明，Co0.9Ni0.1TiO3在所研究的氧化物中表现出最好的ORR活性，具有较高的阴极电流密度，较低的电荷转移电阻，较低的Tafel斜率，较高的交换电流密度，增加的ECSA，以及与Pt/C相似的明显的近四电子ORR途径。Co0.9Ni0.1TiO3也表现出优异的甲醇耐受性，在含1 M甲醇的1 M KOH中，10000 s后仍能保持84.36%的电流，在无甲醇的1 M KOH中，2万s后仍能保持89.98%的电流，这凸显了其作为一种经济高效的ORR电催化剂的潜力。
{"title":"Ni-Doped CoTiO3 Ilmenite Oxides as Durable and Methanol-Tolerant Electrocatalysts for Oxygen Reduction Reaction","authors":"Shaikh Parwaiz,Fazlurrahman Khan,Min-Ung Kim,James Robert Jennings,Mohammad Hilni Harunsani,Young-Mog Kim,Mohammad Mansoob Khan","doi":"10.1021/acs.jpcc.6c03772","DOIUrl":"https://doi.org/10.1021/acs.jpcc.6c03772","url":null,"abstract":"Developing cost-effective, methanol-tolerant oxygen reduction reaction (ORR) electrocatalysts is critical for alkaline fuel cells and metal–air batteries. This study presents the synthesis of CoTiO3 and Co1–xNixTiO3 (x = 0.1 and 0.2) ilmenite oxides via a sol–gel method and thoroughly examines the influence of Ni substitution in CoTiO3 on its ORR performance. XRD, FTIR, Raman, and XPS analyses confirmed the formation of the ilmenite CoTiO3 framework, successful Ni incorporation, and Ni-induced modulation of the metal–oxygen environment. TEM and FE-SEM analyses revealed nearly spherical nanoparticles, while EDAX verified the expected constituent elements. BET analysis showed that Co0.9Ni0.1TiO3 possessed the highest surface area and pore volume, supporting improved active-site accessibility. Electrocatalytic ORR studies in O2-saturated 1 M KOH demonstrated that Co0.9Ni0.1TiO3 exhibited the best ORR activity among the investigated oxides, with higher cathodic current density, lower charge-transfer resistance, lower Tafel slope, higher exchange current density, increased ECSA, and an apparent near-four-electron ORR pathway, comparable to Pt/C. Co0.9Ni0.1TiO3 also showed excellent methanol tolerance, retaining 84.36% current after 10,000 s in 1 M KOH containing 1 M methanol and 89.98% after 20,000 s in methanol-free 1 M KOH, highlighting its potential as a cost-effective ORR electrocatalyst.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"56 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2026-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-19DOI: 10.1021/acs.jpcc.6c05538
G. B. Netto,A. F. V. Fonseca,A. P. Machado,A. F. Nogueira,J. P. Siqueira
We investigate the microscopic origin of the enhanced photoconductivity and charge carrier transport in a mixed-cation, mixed-halide hybrid perovskite passivated with CsPbBr3 quantum dots using optical pump-terahertz probe spectroscopy. We directly access the complex transient photoconductivity in the terahertz range, whose analysis allows us to elucidate the effect of CsPbBr3 quantum dot passivation on charge carrier transport between crystalline domains. We find that, for the passivated perovskites, transport properties are significantly improved, with the Drude–Smith backscattering parameter changing from −0.60 to −0.42, corresponding to a 43% increase in carrier mobility, while the intragrain carrier scattering time (≈110 fs) remains unchanged. These results demonstrate that the enhanced photoconductivity originates from reduced carrier backscattering at grain boundaries, rather than changes in intragrain carrier scattering. Our results provide microscopic insight into the mechanism underlying the improved performance of solar cells based on mixed-cation, mixed-halide hybrid perovskites passivated with CsPbBr3 quantum dots.
{"title":"Unraveling the Microscopic Origin of Photoconductivity Enhancement in CsPbBr3 Quantum Dot-Passivated Hybrid Perovskites by Optical Pump-Terahertz Probe Spectroscopy","authors":"G. B. Netto,A. F. V. Fonseca,A. P. Machado,A. F. Nogueira,J. P. Siqueira","doi":"10.1021/acs.jpcc.6c05538","DOIUrl":"https://doi.org/10.1021/acs.jpcc.6c05538","url":null,"abstract":"We investigate the microscopic origin of the enhanced photoconductivity and charge carrier transport in a mixed-cation, mixed-halide hybrid perovskite passivated with CsPbBr3 quantum dots using optical pump-terahertz probe spectroscopy. We directly access the complex transient photoconductivity in the terahertz range, whose analysis allows us to elucidate the effect of CsPbBr3 quantum dot passivation on charge carrier transport between crystalline domains. We find that, for the passivated perovskites, transport properties are significantly improved, with the Drude–Smith backscattering parameter changing from −0.60 to −0.42, corresponding to a 43% increase in carrier mobility, while the intragrain carrier scattering time (≈110 fs) remains unchanged. These results demonstrate that the enhanced photoconductivity originates from reduced carrier backscattering at grain boundaries, rather than changes in intragrain carrier scattering. Our results provide microscopic insight into the mechanism underlying the improved performance of solar cells based on mixed-cation, mixed-halide hybrid perovskites passivated with CsPbBr3 quantum dots.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"413 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2026-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218953","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}
Understanding the impact of transition-metal doping on the optoelectronic properties of halide perovskite nanocrystals is essential for their rational design in photonic applications. We establish the microscopic origin of photoluminescence (PL) quenching in Fe-doped CsPbCl3 using spin-polarized density functional theory calculations. The emergence of Fe 3d midgap states creates efficient electron-trapping centers that drive nonradiative recombination, accounting for the reduced PL intensity. Extending this analysis to Fe-doped CsPbX3 (X = Cl, Br), we show experimentally that although PL intensity is suppressed in both systems relative to their pristine counterparts, their high-doping behavior diverges: CsPbCl3 becomes completely non-emissive, whereas CsPbBr3 retains a finite, saturated PL intensity. Despite this contrast, electronic structure calculations reveal nearly identical midgap states in both materials, indicating that electronic effects alone cannot explain the distinct PL responses. Phonon calculations likewise fail to capture this difference. In contrast, electron-phonon coupling calculations based on the deformation potential approach reveal significantly stronger coupling in Fe-doped CsPbCl3, enabling efficient dissipation of electronic excitation energy into lattice vibrations and leading to complete PL quenching. These results identify electron-phonon coupling as the key factor governing halide-dependent PL quenching and provide a unified microscopic framework for dopant-induced nonradiative processes in halide perovskites.
{"title":"Why Fe Doping Kills Photoluminescence in CsPbCl3 but Not in CsPbBr3: Role of Midgap Fe 3d States and Electron-Phonon Coupling","authors":"Arpan Das,Saptarshi Chakraborty,Ranjani Viswanatha,Shobhana Narasimhan","doi":"10.1021/acs.jpcc.6c05087","DOIUrl":"https://doi.org/10.1021/acs.jpcc.6c05087","url":null,"abstract":"Understanding the impact of transition-metal doping on the optoelectronic properties of halide perovskite nanocrystals is essential for their rational design in photonic applications. We establish the microscopic origin of photoluminescence (PL) quenching in Fe-doped CsPbCl3 using spin-polarized density functional theory calculations. The emergence of Fe 3d midgap states creates efficient electron-trapping centers that drive nonradiative recombination, accounting for the reduced PL intensity. Extending this analysis to Fe-doped CsPbX3 (X = Cl, Br), we show experimentally that although PL intensity is suppressed in both systems relative to their pristine counterparts, their high-doping behavior diverges: CsPbCl3 becomes completely non-emissive, whereas CsPbBr3 retains a finite, saturated PL intensity. Despite this contrast, electronic structure calculations reveal nearly identical midgap states in both materials, indicating that electronic effects alone cannot explain the distinct PL responses. Phonon calculations likewise fail to capture this difference. In contrast, electron-phonon coupling calculations based on the deformation potential approach reveal significantly stronger coupling in Fe-doped CsPbCl3, enabling efficient dissipation of electronic excitation energy into lattice vibrations and leading to complete PL quenching. These results identify electron-phonon coupling as the key factor governing halide-dependent PL quenching and provide a unified microscopic framework for dopant-induced nonradiative processes in halide perovskites.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"56 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2026-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-19DOI: 10.1021/acs.jpcc.6c05855
Heesoo Park,Chris Erik Mohn,David S. Wragg,Alexey Y. Koposov
Capturing the cross-layer kinetics of intercalants remains a fundamental bottleneck in understanding the structural evolution of layered host materials. This challenge is particularly critical in Li-ion batteries, where designing high-rate graphite anodes is hindered by a lack of mechanistic understanding of intercalation, because theoretical models traditionally address structural order only as out-of-plane staging or in-plane migration. Here, we expanded molecular dynamics simulation dimensions to over 8 nm with 12 graphite layers to fully account for dynamic intra- and interlayer correlations. We observed the collective atomistic evolution at various stages of lithiation, revealing unusual diffusive behavior; for example, upper-layer Li islands regulate the diffusivity of the two underlying layers at stage 3. Furthermore, Li-ion transport becomes highly in-plane anisotropic under the steep concentration gradients characteristic of high-rate operation. By explicitly connecting three-dimensional staging with two-dimensional diffusion, these insights provide the realistic mechanistic baseline necessary for predictive macroscale modeling.
{"title":"From Disorder to Staging: Mechanism of Li-ion Diffusion in Graphite Revealed by Large-Scale Molecular Dynamics","authors":"Heesoo Park,Chris Erik Mohn,David S. Wragg,Alexey Y. Koposov","doi":"10.1021/acs.jpcc.6c05855","DOIUrl":"https://doi.org/10.1021/acs.jpcc.6c05855","url":null,"abstract":"Capturing the cross-layer kinetics of intercalants remains a fundamental bottleneck in understanding the structural evolution of layered host materials. This challenge is particularly critical in Li-ion batteries, where designing high-rate graphite anodes is hindered by a lack of mechanistic understanding of intercalation, because theoretical models traditionally address structural order only as out-of-plane staging or in-plane migration. Here, we expanded molecular dynamics simulation dimensions to over 8 nm with 12 graphite layers to fully account for dynamic intra- and interlayer correlations. We observed the collective atomistic evolution at various stages of lithiation, revealing unusual diffusive behavior; for example, upper-layer Li islands regulate the diffusivity of the two underlying layers at stage 3. Furthermore, Li-ion transport becomes highly in-plane anisotropic under the steep concentration gradients characteristic of high-rate operation. By explicitly connecting three-dimensional staging with two-dimensional diffusion, these insights provide the realistic mechanistic baseline necessary for predictive macroscale modeling.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"285 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2026-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-10-19DOI: 10.1021/acs.jpcc.6c05013
Bianca Ligt,Jérôme F. M. Simons,Jason M. J. J. Heinrichs,Laura B. Donk,Marta Costa Figueiredo,Emiel J. M. Hensen
Using potential pulses in Cu-catalyzed CO2 electroreduction (CO2RR) has recently shown great promise in steering product selectivity. However, the effect of these pulses on the catalyst structure and, therefore, the formation of C1 and C2 products remain unclear. Herein, we altered the applied potential of the anodic pulse and varied the duration of the cathodic CO2RR pulse to investigate the effect of both the oxidation state and restructuring of an oxide-derived Cu nanoparticle catalyst on the CO2RR. Shorter cathodic pulses and a higher anodic pulse potential led to a higher ethanol-to-ethylene Faradaic efficiency (FE) ratio, an increase in the C1 FE, and a suppression of the hydrogen evolution reaction (HER). We tracked the structural evolution of the CuO catalyst by in situ X-ray absorption spectroscopy (XAS) during the (pulsed) CO2RR. The CuO catalyst was fully reduced under potentiostatic conditions, whereas residual CuOx was detected during pulsed CO2 electrolysis. Quasi-in situ X-ray photoelectron spectroscopy (XPS) further emphasized that the surface of the Cu catalyst was significantly impacted by the application of potential pulses, whereby a higher fraction of CuOx was observed with the application of shorter cathodic pulses and higher anodic pulse potentials. Moreover, X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed that sintering and defect formation took place during pulsed CO2RR, resulting in an irreversible morphological change, which was associated with the enhanced formation of C1 products.
{"title":"Impact of Pulsed CO2 Electrolysis on Surface Structures and Product Distribution for Oxide-Derived Cu","authors":"Bianca Ligt,Jérôme F. M. Simons,Jason M. J. J. Heinrichs,Laura B. Donk,Marta Costa Figueiredo,Emiel J. M. Hensen","doi":"10.1021/acs.jpcc.6c05013","DOIUrl":"https://doi.org/10.1021/acs.jpcc.6c05013","url":null,"abstract":"Using potential pulses in Cu-catalyzed CO2 electroreduction (CO2RR) has recently shown great promise in steering product selectivity. However, the effect of these pulses on the catalyst structure and, therefore, the formation of C1 and C2 products remain unclear. Herein, we altered the applied potential of the anodic pulse and varied the duration of the cathodic CO2RR pulse to investigate the effect of both the oxidation state and restructuring of an oxide-derived Cu nanoparticle catalyst on the CO2RR. Shorter cathodic pulses and a higher anodic pulse potential led to a higher ethanol-to-ethylene Faradaic efficiency (FE) ratio, an increase in the C1 FE, and a suppression of the hydrogen evolution reaction (HER). We tracked the structural evolution of the CuO catalyst by in situ X-ray absorption spectroscopy (XAS) during the (pulsed) CO2RR. The CuO catalyst was fully reduced under potentiostatic conditions, whereas residual CuOx was detected during pulsed CO2 electrolysis. Quasi-in situ X-ray photoelectron spectroscopy (XPS) further emphasized that the surface of the Cu catalyst was significantly impacted by the application of potential pulses, whereby a higher fraction of CuOx was observed with the application of shorter cathodic pulses and higher anodic pulse potentials. Moreover, X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed that sintering and defect formation took place during pulsed CO2RR, resulting in an irreversible morphological change, which was associated with the enhanced formation of C1 products.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"11 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2026-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218908","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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