{"title":"Capturing Even the Invisible: A Comprehensive Understanding of Methyl Viologen Adsorption Distribution on Clay Nanosheets","authors":"Emiko Nakayama, Yohei Ishida, Yoshinori Tahara, Tetsuya Shimada, Shinsuke Takagi","doi":"10.1021/acs.jpcc.6c04409","DOIUrl":"10.1021/acs.jpcc.6c04409","url":null,"abstract":"<p>Fullyunderstanding how dye molecules distribute over a solid surfacedemands three things at once: capturing the entire population─includinga nonemissive component invisible to both steady-state fluorescenceand fluorescence-lifetime measurements─pinpointing the interactionsthat govern it, and proving that it can be deliberately controlled.Here, we achieved all three for the system of methyl viologen (MV<sup>2+</sup>) and synthetic saponite (SSA). First, using the differencebetween the emission-intensity ratio obtained by steady-state fluorescenceand that obtained from fluorescence lifetimes, we quantified the adsorptiondistribution─including the nonemissive H-aggregate that doesnot appear in fluorescence measurements─as three states: (i)isolated adsorbed monomers, (ii) closely spaced monomers self-quenchedby intermolecular electron transfer, and (iii) nonemissive H-aggregates.The H-aggregate population reached about 70% of all adsorbed speciesat a loading of 50% relative to the CEC. Second, a van’t Hoffanalysis of the equilibrium between the isolated and closely spacedmonomers separated Δ<em>H</em> (electrostatic attraction,which stabilizes the isolated arrangement) and Δ<em>S</em> (hydrophobic interaction, which stabilizes the closely spaced arrangement),showing that Δ<em>S</em> dominates at 293 K. Third,lengthening the alkyl chain from C1 to C8, which strengthens the hydrophobicinteraction without changing the cationic charge, shifted the closelyspaced (short-lifetime) fraction from 63% to 88%, thereby demonstratingcontrol of the adsorption distribution. Through quantification includingthe invisible component, thermodynamic understanding, and demonstratedcontrol, this work provides a comprehensive understanding of a complexadsorption distribution and a guideline for designing two-dimensionaldye arrays on inorganic surfaces.</p>","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"130 41","pages":"14330–14338"},"PeriodicalIF":3.4,"publicationDate":"2026-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149090627","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}
{"title":"Regulating Exciton Dynamics through Molecular Packing in Conjugated Polymer Nanoparticles for Photocatalytic H2O2 Production","authors":"Avijit Patra, Soham Ghosh, Santanu Bhattacharyya","doi":"10.1021/acs.jpcc.6c05248","DOIUrl":"10.1021/acs.jpcc.6c05248","url":null,"abstract":"<p>Herein, two different types of poly[(9,9-dioctylfluorenyl-2,7-diyl)-<em>co</em>-(1,4-benzo-{2,1’,3}-thiadiazole)] (PFBT) polymernanoparticles have been fabricated by varying the molecular packingthrough solution-based miniemulsion techniques at various surfactantconcentrations. The structural features and intermolecular interactionshave been correlated with the underlying photophysical properties.The results suggest that at higher surfactant concentrations, polymermolecules follow highly defined molecular arrangements which enhancethe effective π-conjugation within the nanoparticles. As a result,efficient charge separation is improved by minimizing the excitonbinding energy and increasing the exciton diffusion length. Furthermore,charge separation through highly defined molecular packing facilitatesthe intrinsic transient dipole moment in the excited state of thenanoparticle, providing an additional driving force to the excitondiffusion process. On the contrary, the random packing of the conjugatedpolymer molecules within nanoparticles hinders charge separation andfree carrier migration by creating unwanted defects or trap statesthroughout the nanoparticles, which essentially creates localizedstrong binding excitons. As a result, the photocatalytic activitydecreases. Overall, the present work defines a simple solution-basedstrategy to regulate exciton dynamics in conjugated polymer nanoparticlesand their utilization for photocatalytic H<sub>2</sub>O<sub>2</sub> production.</p>","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"130 41","pages":"14119–14129"},"PeriodicalIF":3.4,"publicationDate":"2026-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149090587","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}
Shuang Huang, Na Yang, Qiong Xiang, Li Li, Zidong Wei
{"title":"Distance and Coordination Synergy in FeCoNC Dual-Atom Catalysts: Volcano-Type Structure-Activity-Stability Relationship for the ORR","authors":"Shuang Huang, Na Yang, Qiong Xiang, Li Li, Zidong Wei","doi":"10.1021/acs.jpcc.6c05363","DOIUrl":"10.1021/acs.jpcc.6c05363","url":null,"abstract":"<p>Developing non-precious-metal catalysts with high activityandstability for the oxygen reduction reaction (ORR) remains a centralchallenge for polymer electrolyte membrane fuel cells. While Fe–Codual-atom catalysts have attracted considerable interest, the interplaybetween Fe–Co distance and local coordination environment ingoverning activity and stability is not well understood. Here, wesystematically investigate FeCoNC models with varying Fe–Codistances and N coordination numbers using density functional theoryand ab initio molecular dynamics simulations. A clear structure–activity–stabilityrelationship emerges: the Fe–N<sub>4</sub>/Co–N<sub>4</sub> configuration at intermediate Fe–Co distance deliversoptimal overall performance, exhibiting low ORR overpotential andhigh electrochemical stability. This balanced behavior stems frommoderate Fe–Co d-orbital coupling, which tunes the spin densityand charge distribution to yield favorable adsorption strength, whileN<sub>4</sub> coordination and Fe–Co interaction strengthenmetal–support anchoring and suppress metal oxidation and dissolution.Excessively short Fe–Co distances with N<sub>2</sub>/N<sub>3</sub> coordination increase spin density and unbalance charge distribution,reducing activity and stability, whereas large separations weakendual-atom synergy, causing the sites to behave as isolated singleatoms. This work establishes a design principle for dual-atom ORRcatalysts: controlled Fe–Co spacing and N<sub>4</sub> coordinationenable balanced d-orbital coupling and charge transfer, achievingboth high activity and long-term stability.</p>","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"130 41","pages":"14184–14192"},"PeriodicalIF":3.4,"publicationDate":"2026-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149090623","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}
{"title":"Comment on “Homogeneous Catalysis of Electrochemical Reactions: The Steady-State Current and Turnover Frequency”","authors":"Christopher C. Tisdell","doi":"10.1021/acs.jpcc.6c04623","DOIUrl":"https://doi.org/10.1021/acs.jpcc.6c04623","url":null,"abstract":"","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"130 41","pages":"14371–14372"},"PeriodicalIF":3.4,"publicationDate":"2026-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149188022","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}
Hicham Idriss, Ahmed Ziani, Muhammad Amtiaz Nadeem
{"title":"Resolving Overlapping Optical Transitions in CeO2 by Derivative Analysis of UV–Vis Spectra: Application to Au/CeO2","authors":"Hicham Idriss, Ahmed Ziani, Muhammad Amtiaz Nadeem","doi":"10.1021/acs.jpcc.6c05148","DOIUrl":"https://doi.org/10.1021/acs.jpcc.6c05148","url":null,"abstract":"<p>The effect of Aunanoparticles on the energy transitionand associatedband gap of CeO<sub>2</sub> has been studied by UV–vis absorbancethen analyzed by the Tauc, first derivative (dA/dλ), and secondderivative (d<sup>2</sup>A/dλ<sup>2</sup>) methods; A: absorbanceand λ: wavelength. CeO<sub>2</sub> mean particles size is ca.12 nm while those of Au were 4–7 nm for the investigated series(with Au wt % = 1, 2 and 4). For CeO<sub>2</sub>, two clear transitionsare observed and are attributed to O 2p to Ce 4f<sup>0</sup> (Ce<sup>4+</sup>) and O 2p to 4f<sup>0</sup>/4f<sup>1</sup> (Ce<sup>4+</sup> close to Ce<sup>3+</sup>/V<sub>O</sub>; V<sub>O</sub>: oxygen vacancy)with the former having a higher energy than the latter. The presenceof Au largely suppressed the weaker transition associated with defectsstates (Ce<sup>3+</sup>/V<sub>O</sub>). This was observed in the firstderivative plots where a blue-shift of 22 nm is seen and a narrowingof the Full Width at Half Maximum of peaks by up to 35 nm when comparedto CeO<sub>2</sub> alone. The second derivative plots showed a morepronounced shift at the low energy side with an extracted band gapenergy of 2.9 eV that shifted to 3.2 eV for 4 wt % Au/CeO<sub>2</sub>, while the high energy side (at ca. 3.6 eV) was largely unchanged.These changes, collectively attributed to Au particles, might be linkedto decreased defects centers in Au/CeO<sub>2</sub> catalysts whencompared to CeO<sub>2</sub> alone. Therefore, the first derivativegives qualitative assessment of the role of Au in CeO<sub>2</sub> forlight absorption while the second derivative gives a more quantitativeinformation on the optical transitions. On the contrary, the Taucplots, while identified both transitions, were insensitive.</p>","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"130 41","pages":"14363–14370"},"PeriodicalIF":3.4,"publicationDate":"2026-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149188074","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}
{"title":"Ultrathin Cerium\u0000Oxide Islands on Cu(111): Work Function\u0000and Reaction with Oxygen and Hydrogen at RT","authors":"Clemens Barth","doi":"10.1021/acs.jpcc.6c04325","DOIUrl":"https://doi.org/10.1021/acs.jpcc.6c04325","url":null,"abstract":"Abstract Ultrathin oxide films can significantly change the work function (WF) of metal surfaces, with large consequences for the adsorption of nanoparticles and molecules on the films. In contrast to other oxides, little is known about the impact of ultrathin cerium oxide (ceria) films on the metal WF, particularly with regard to the reducibility of ceria. Here, it is shown that oxidized ceria islands in the submonolayer range reduce the WF of Cu(111) by at least −0.25 eV, while reduced ceria islands strongly decrease the metal WF by more than −1 eV, as measured by Kelvin probe force microscopy (KPFM) under ultrahigh-vacuum (UHV) conditions. A possible model suggests that the significant WF modifications upon reduction are due to an electron transfer from ceria’s oxygen vacancies into the Cu support, as most of the interfacial Ce ions are already in the 3+ state after the thin-film preparation. As observed by KPFM, reduced ceria islands become immediately oxidized at room temperature (RT) when exposed to a few Langmuir of O2 due to the filling of oxygen vacancies with O. In contrast, H2 at RT generally does not affect ceria, nor does it affect the WF.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"11 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2026-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149209269","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}