Physical Chemistry Chemical Physics最新文献

{"title":"Investigation of perovskite materials for solar cells using scanning tunneling microscopy.","authors":"Yule Wang, Bin-Bin Cui, Yiming Zhao, Tao Lin, Juan Li","doi":"10.1039/d4cp02010c","DOIUrl":"https://doi.org/10.1039/d4cp02010c","url":null,"abstract":"<p><p>The issue of energy scarcity has become more prominent due to the recent scientific and technological advancements. Consequently, there is an urgent need for research on sustainable and renewable resources. Solar energy, in particular, has emerged as a highly promising option because of its pollution-free and environment-friendly characteristics. Among the various solar energy technologies, perovskite solar cells have attracted much attention due to their lower cost and higher photoelectric conversion efficiency (PCE). However, the inherent instability of perovskite materials hinders the commercialization of such devices. The utilization of scanning tunneling microscopy/spectroscopy (STM/STS) can provide valuable insights into the fundamental properties of different perovskite materials at the atomic scale, which is crucial for addressing this challenge. In this review, we present the recent research progress of STM/STS analysis applied to various perovskites for solar cells, including halide perovskites, two-dimensional Ruddlesden-Popper perovskites, and oxide perovskites. This comprehensive overview aims to inspire new ideas and strategies for optimizing solar cells.</p>","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142386476","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":"Product branching in the photodissociation of oxazole detected by broadband rotational spectroscopy","authors":"Briony Downes-Ward, Abbas Behzadfar, Shameemah Thawoos, Arthur Suits","doi":"10.1039/d4cp03276d","DOIUrl":"https://doi.org/10.1039/d4cp03276d","url":null,"abstract":"The photodissociation of oxazole (c-C3H3NO) following excitation at 193 nm is studied using mm-Wave rotational spectroscopy in a uniform supersonic flow. Molecules entrained in the flow are excited onto a ππ* state after which it is believed most relax back onto the ground state via ring opening at the O-C[N] bond with subsequent fragmentation. From the line intensities of the probed products, we obtained the branching fractions for seven different products which are the result of five different dissociation pathways. The detected photoproducts and respective branching fractions (%) are the following: HCN (70.4), HCO (22.8), CH2CN (4.2), CH2CO (1.0), CH3CN (1.0), HNC (0.9), HNCO (0.08). We suspect much of the HCO may be formed in conjunction with the isocyanomethyl radical, CH2NC, which we did not probe. We discuss our results in relation to previous work, in particular our own study on the related isomer isoxazole, as well as direct dynamics theoretical simulations from the literature. We also studied the relaxation of a number of vibrationally excited levels of HCN produced at 20 K.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142385193","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":"Time-pH and Time-Humidity Scaling of Ionic Conductivity Spectra of Polyelectrolyte Multilayers","authors":"Jannis Schlicke, Cornelia Cramer, Monika Schönhoff","doi":"10.1039/d4cp03482a","DOIUrl":"https://doi.org/10.1039/d4cp03482a","url":null,"abstract":"In this systematic study, ionic conductivity spectra of poly(diallyl-dimethylammonium)/ poly(acrylic acid) (PDADMA/PAA)n polyelectrolyte multilayers (PEMs) are investigated regarding superposition principles. In this context, charge transport as well as charge compensation processes in polyelectrolyte assemblies are discussed. The validity of different scaling concepts is tested to differentiate between changes in the mobility and charge carrier density, caused by the variation of a parameter X, where X is either relative humidity during measurement, or salt concentration or pH during preparation. For the first time, time-X scaling for conductivity spectra of PEMs is reported for all three parameters X, resulting in individual mastercurves. Furthermore, a super-mastercurve can be obtained including variations of all three parameters. Changes in plasticization caused by either varied humidity, pH or ionic strength imply non-constant charge carrier mobilities in accordance with a Summerfield-type of scaling, while the charge carrier density remains constant. Interestingly, for preparation conditions which favor extrinsic charge compensation, significant deviations from such Summerfield-type scaling are observed, indicating a variation of the number density of mobile charge carriers with humidity.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142385194","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":"Operando Spectroscopy Investigations of the Redox Reactions in Heme and Heme-Proteins","authors":"Subhankar Mandal, Dipen Biswakarma, Aninda Jiban Bhattacharyya","doi":"10.1039/d4cp03341h","DOIUrl":"https://doi.org/10.1039/d4cp03341h","url":null,"abstract":"Operando spectroscopic investigations during molecular redox processes provide unique insights into complex molecular structure and their transformations. Herein, a combination of a potentiodynamic method with spectroscopy has been employed to holistically investigate the structural transformations during Fe-redox (Fe3+Fe2+) of hemin vis á vis heme-proteins e.g. myoglobin (Mb), hemoglobin (Hb) and cytochrome-C (Cyt-C). The UV-VIS findings reveal the formation of hemozoin ( heme-dimer), which can be selectively prevented via a high concentration of strongly interacting ligands e.g. histidine (the fifth coordinating ligand in the heme-based protein). On the other hand, methionine does not prevent the formation of hemozoin. In Mb, Hb, and Cyt-C, as the fifth coordination site is occupied by histidine, hemozoin formation is inhibited. During Fe3+ Fe2+, operando circular dichroism exhibits a decrease in the initial helical component in Hb from nearly 40% to 28%, which is close to the initial helix component of Mb ( 25%), strongly indicating denaturation of protein in the redox pathway. The rate of change of the helices versus potential is almost identical for Mb and Hb, but comparatively faster than Cyt-C. In addition, the Raman bands of M-N dynamics and protein agglomeration, it is concluded that Cyt-C prefers to agglomerate in the 2+ state, whereas Mb/Hb in the 3+ state. Using the power of operando spectroscopy, the present study unearths complexities associated with molecular redox having implications in electrocatalysis, energy storage, and sensing.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142385253","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":"Vacuum-ultraviolet irradiation of pyridine:acetylene ices relevant to Titan astrochemistry","authors":"Larissa Lopes Cavalcante, Ellen Claire Czaplinski, Helen Elizabeth Maynard-Casely, Morgan Leigh Cable, Naila Chaouche-Mechidal, Robert Hodyss, Courtney Ennis","doi":"10.1039/d4cp03437f","DOIUrl":"https://doi.org/10.1039/d4cp03437f","url":null,"abstract":"Nitrogen-containing polycyclic aromatic hydrocarbons (NPAHs) are important molecules for astrochemistry and prebiotic chemistry, as their occurrence spans from interstellar molecular clouds to planetary systems. Their formation has been previously explored in gas phase experiments, but the role of solid-state chemical reactions in their formation under cryogenic conditions remains elusive. Here, we explore the formation of NPAHs through vacuum ultraviolet (VUV) irradiation of pyridine:acetylene ices in amorphous and co-crystalline phases, with the aim to simulate conditions relevant to the interstellar medium and Titan's atmosphere. Our results show that the synthesis of ethynylpyridines from VUV-irradiated pyridine:acetylene amorphous ices is achievable at 18 K. In the co-crystal phase, photolysis at 110 K leads to the formation of NPAHs such as quinolizinium and precursors, reflecting a dynamical system under our conditions. In contrast, irradiation at 90 K under stable conditions did not produce volatile photoproducts. These results suggest that such chemical processes can occur in Titan's atmosphere and potentially in its stratosphere, where the co-condensation of these molecules can form composite ices. Concurrently, the formation of stable co-crystals can influence the depletion rates of pyridine, which suggests that these heterocycles can be preserved and potentially delivered to Titan's surface. Our findings provide insights into the molecular diversity and chemical evolution of organic matter on Titan, which will be crucial for future exploration, such as the Dragonfly mission in its search for higher-order organics derived from pyridine precursors on Titan's surface.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142385254","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":"Physical mechanisms of the Sec machinery operation","authors":"Ekaterina Sobakinskaya, Frank Müh","doi":"10.1039/d4cp03201b","DOIUrl":"https://doi.org/10.1039/d4cp03201b","url":null,"abstract":"The Sec complex, composed of a motor protein SecA and a channel SecYEG, is an ATP-driven molecular machine for the transport of proteins across the plasma membrane in bacteria. Today, there is a consensus about a general “rough” model of the complex activation and operation, which, however, lacks understanding of the physical mechanisms behind it. Molecular dynamics simulations were employed to address a way of allosteric activation, conformational transition of SecYEG from the closed to the open state and driving forces of protein transport. We found that binding of SecA (in the ATP-bound state) and the protein signal sequence leads to a transmembrane helix rearrangment that weakens contacts inside the hydrophobic core of SecYEG and provides a driving force for plug opening. The conformational transitions are enabled by a delicate interplay between hydrophobic forces on one side and PEES (Proton motive force, External – due to binding with the translocation partners – Entropic and Solvent-induced) on the other side. In the open state, SecYEG still provides a barrier for bulky residues that contributes to the driving forces of transport. Other important contributions come from SecA and the membrane potential acting in different stages of protein transport to guarantee a nearly constant driving force. Given that the different forces act on different types of residues, the suggested mechanisms taken together provide a directional motion for any substrate, thereby maximizing the efficiency of the Sec machinery.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142385195","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":"Cobalt Substitution Slows Forsterite Carbonation in Low-Water Supercritical Carbon Dioxide","authors":"John Steven Loring, Tenley E Webb, Mark E Bowden, Mark H Engelhard, Sebastien Kerisit","doi":"10.1039/d4cp02092h","DOIUrl":"https://doi.org/10.1039/d4cp02092h","url":null,"abstract":"Cobalt recovery from low-grade mafic and ultramafic ores could be economically viable if combined with CO2 storage under low-water conditions, but the impact of Co on metal silicate carbonation and the fate of Co during the carbonation reaction must be understood. In this study, in situ infrared spectroscopy was used to investigate the carbonation of Co-doped forsterite ((Mg,Co)2SiO4) in thin water films in humidified supercritical CO2 at 50 °C and 90 bar. Rates of carbonation of Co-doped forsterite to Co-rich magnesite ((Mg,Co)CO3) increased with water film thickness but were at least 10 times smaller than previously measured for pure forsterite at similar conditions. We suggest that the smaller rates are due to thermodynamic drivers that cause water films on Co-doped forsterite to be much less oversaturated with respect to Co-doped magnesite, compared to the pure minerals.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142385192","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":"Theoretical investigation of Cu5/silicates deposited on rutile TiO2 as a photocatalyst","authors":"Fatimah Alhawiti, Qingqing Wu, David Buceta, Songjun Hou, Manuel Arturo Lopez-Quintela, Colin Lambert","doi":"10.1039/d4cp02903h","DOIUrl":"https://doi.org/10.1039/d4cp02903h","url":null,"abstract":"Titanium dioxide (TiO2) is an exceptional compound with unique optical properties, which have been intensively used for applications in photocatalysis. Recent studies show that Cu5 atomic quantum clusters (AQCs) could facilitate visible light absorption and enhance the photocatalytic properties of rutile TiO2 by creating mid-gap states. In this work, to move the theory of these catalysts closer to the experiment, we investigate the electronic structures of Cu5 adsorbed on a perfect and reduced rutile TiO2 surface in the absence and presence of silicate SiO_3^(2-) ions, which are introduced for the purification of Cu5 AQCs. Encouragingly, our DFT simulations predict that the presence of SiO_3^(2-) does not reduce the gap states of the Cu5@TiO2 composite and could even enhance them by shifting more states into the band gap. Our results also demonstrate that the polarons created by oxygen vacancies (Ov) and Cu5 coexist within the band gap of TiO2. Indeed an Ov behaves like a negative gate on the electronic states located on the AQCs, thereby shifting states out of the valence band into the band gap, which could lead to enhanced photocatalytic performance.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142385648","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":"Support effects on conical intersections of Jahn-Teller fluxional metal clusters on the sub-nanoscale","authors":"Katarzyna M. Krupka, María Pilar de Lara-Castells","doi":"10.1039/d4cp03271c","DOIUrl":"https://doi.org/10.1039/d4cp03271c","url":null,"abstract":"The concept of fluxionality has been invoked to explain the enhanced catalytic properties of atomically precise metal clusters of subnanometer size. Cu<small>₃</small> isolated in the gas phase is a classical fluxional metal cluster where a conical intersection leads to a Jahn-Teller (JT) distortion resulting in a potential energy landscape with close-lying multiminima and, ultimately, fluxional behavior. In spite of the role of conical intersections in the (photo)stability and (photo)catalytic properties of surface-supported atomic metal clusters, they are largely unexplored. In this work, by applying a high-level multi-reference <em>ab initio</em> method aided with dispersion corrections, we analyze support effects on the conical intersection of Cu<small>₃</small> considering benzene as a model support molecule. We verify that the region around the conical intersection and the associated Jahn-Teller (JT) distortion is very slightly perturbed by the support when the Cu<small>₃</small> cluster approaches it in a parallel orientation: Two electronic states remain degenerate for a structure with a C<small>₃</small> symmetry consistent with the D<small>_3h</small> symmetry of unsupported Cu<small>₃</small> at the conical intersection. It extends over a one-dimensional seam that characterizes a physisorption minimum of the Cu<small>₃</small>-benzene complex. The fluxionality of the Cu<small>₃</small> cluster, reflected in large fluctuations of relaxed Cu-Cu distances as function of the active JT mode, is kept unperturbed upon complexation with benzene as well. In stark contrast, for the energetically favored perpendicular orientation of the Cu<small>₃</small> plane to the benzene ring plane, the conical intersection (CI) is located ~1.5 eV above the chemisorption minimum, with the fluxionality being kept at the CI's nearby and lost at the chemisorption well. The first excited state at the perpendicular orientation has a deep well, being energetically closer to the CI. The transition dipole moment between ground and excited states has a significant magnitude, suggesting that the excited state can be observed through direct photo-excitation from the ground state. Besides demonstrating that the identity of an isolated Jahn-Teller metal cluster can be preserved against support effects at a physisorption state and lifted out at a chemisorption state, our results indicate that a correlation exists between conical intersection topography and fluxionality in the metal cluster's Cu-Cu motifs.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142397886","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":"Copper binding alters the core structure of amyloid fibrils formed by Y145Stop human prion protein","authors":"Vidhyalakshmi Sridharan, Tara George, Daniel Conroy, Zach Shaffer, Witold Surewicz, Christopher Jaroniec","doi":"10.1039/d4cp03593c","DOIUrl":"https://doi.org/10.1039/d4cp03593c","url":null,"abstract":"Transmissible spongiform encephalopathies (or prion diseases) such as Creutzfeldt-Jacob disease, mad cow disease, and scrapie are characterized by accumulation in the brain of misfolded prion protein aggregates (PrPSc) that have properties of amyloid fibrils. Given that transition metal ions, such as copper and zinc, appear to be important for physiological functions of cellular PrP (PrPC) as well as for prion disease pathogenesis, exploring their role in the protein aggregation process is of considerable interest. Copper(II) in particular is well-known to bind to the four tandem octapeptide repeats (PHGGGWGQ) located in the N-terminal region of PrP (human PrP amino acids 60-91), as well as to additional histidine binding sites outside the octarepeat region with distinct binding modes depending on Cu2+ concentration. Here, using the Y145Stop human prion protein variant (huPrP23-144) as a model and a combination of multidimensional solution and solid-state NMR spectroscopy, atomic force microscopy and thioflavin T fluorescence assays we probed the binding of Cu2+ to monomeric huPrP23-144 and the impact of this binding on fibril assembly kinetics and their structural properties. Remarkably, we found that fibrils formed by huPrP23-144 containing one molar equivalent of bound Cu2+ adopt a core structure that is distinct from that found for huPrP23-144 in the absence of Cu2+ but, instead, corresponds to a conformational strain formed by huPrP23-144 containing the A117V mutation. A similar huPrP23-144 A117V-like amyloid core structure was adopted by a Cu2+-bound Δ51-91 huPrP23-144 deletion variant lacking the entire octarepeat region, suggesting that Cu2+ binding to His residues 96, 111 and 140 located near the C-terminus of huPrP23-144 is primarily responsible for the observed change in fibril conformation, potentially due to partial structuring of the intrinsically disordered huPrP23-144 by the bound Cu2+ during the fibril assembly process. We also found that fibrils formed by Cu2+-bound huPrP23-144 adopt the native huPrP23-144-like rather than A117V-like structure when the fibrillation reaction is seeded with pre-formed huPrP23-144 amyloid.","PeriodicalId":99,"journal":{"name":"Physical Chemistry Chemical Physics","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142384329","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}