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The enzyme FeFe-hydrogenase catalyzes H2 evolution and oxidation at an active site that consists of a [4Fe-4S] cluster bridged to a [Fe2(CO)3(CN)2(azadithiolate)] subsite. Previous investigations of its mechanism were mostly conducted on a few “prototypical” FeFe-hydrogenases, such as that from Chlamydomonas reinhardtii(Cr HydA1), but atypical hydrogenases have recently been characterized in an effort to explore the diversity of this class of enzymes. We aim at understanding why prototypical hydrogenases are active in either direction of the reaction in response to a small deviation from equilibrium, whereas the homologous enzyme from Thermoanaerobacter mathranii (Tam HydS) shows activity only under conditions of very high driving force, a behavior that was referred to as “irreversible catalysis”. We follow up on previous spectroscopic studies and recent developments in the kinetic modeling of bidirectional reactions to investigate and compare the catalytic cycles of Cr HydA1 and Tam HydS under conditions of direct electron transfer with an electrode. We compare the hypothetical catalytic cycles described in the literature, and we show that the observed changes in catalytic activity as a function of potential, pH, and H2 concentration can be explained with the assumption that the same catalytic mechanism applies. This helps us identify which variations in properties of the catalytic intermediates give rise to the distinct “reversible” or “irreversible” catalytic behaviors.

The multiple applications of lead halide perovskite materials and the extensive use of X-ray based techniques to characterize them highlight a need to understand their stability under X-ray irradiation. Here, we present a study where the X-ray stability of five different lead halide perovskite compositions (MAPbI3, MAPbCl3, MAPbBr3, FAPbBr3, CsPbBr3) was investigated using photoelectron spectroscopy. To exclude effects of thin film formation on the observed degradation behaviors, we studied clean surfaces of single crystals. Different X-ray resistance and degradation mechanisms were observed depending on the crystal composition. Overall, perovskites based on the MA+ cation were found to be less stable than those based on FA+ or Cs+. Metallic lead formed most easily in the chloride perovskite, followed by bromide, and only very little metallic lead formation was observed for MAPbI3. MAPbI3 showed one main degradation process, which was the radiolysis of MAI. Multiple simultaneous degradation processes were identified for the bromide compositions. These processes include ion migration towards the perovskite surface and the formation of volatile and solid products in addition to metallic lead. Lastly, CsBr formed as a solid degradation product on the surface of CsPbBr3., De två första författarna delar förstaförfattarskapet

Constructing a Z-scheme heterojunction with enhanced photocatalytic hydrogen evolution for graphitic carbon nitride-based (g-C3N4) composites is challenging because integrating g-C3N4 with other semiconductors, without specific band structure design, typically results in type I or type II heterojunctions. These heterojunctions have lower redox ability and limited enhancement in photocatalysis. Herein, we select highly crystalline carbon nitride (HCCN) as a proof-of-concept substrate. For the first time, we develop a AgBr nanosphere/HCCN composite photocatalyst that features an all -solid -state direct Z-scheme heterojunction for visible-light photocatalytic hydrogen evolution. The electron transfer mechanism is initially studied from the band structures and Fermi levels of HCCN and AgBr. It is subsequently confirmed by X-ray photoelectron spectroscopy (XPS), and electron microscopy. The close heterojunction contact and the built-in electron field of the Z-scheme heterojunction promote the migration and separation of photogenerated electrons and holes in the composite photocatalyst. Due to the redistribution of charge carriers, the photocatalyst shows superior redox capability and a markedly enhanced hydrogen evolution performance compared to its individual components. Combining all the advantages, AgBr nanosphere/HCCN reached an apparent quantum efficiency (AQE) of 6 % under the illumination of 410 nm, which is 4 times higher than that of the single HCCN component.

Indoor photovoltaics (IPV) using dye-sensitized solar cells (DSCs) is one among the most promising ambient energy harvesting technologies used to realize self-powered Internet of Things (IoT), consumer electronics and portable devices. The emergence of new generation Cu(II/I) redox electrolytes used with co-sensitized organic dyes enables DSCs to realize higher open circuit photovoltages (Voc) and power conversion efficiencies (PCE) under indoor/ambient illumination. Even though Cu(II/I) electrolytes are promising candidates, the recombination of electrons from the conduction band and sub-bandgap states to the oxidized Cu(II) species and slower regeneration of Cu(II) at the counter electrode limit their performance. Taking inspiration from the asymmetric redox behaviour exhibited by the conventional iodide/triiodide electrolyte, which is efficient in inhibiting the undesirable recombination process, we introduced an alternative strategy of modifying the coordination environment of Cu(II) metal center using the 2,9-dimethyl-1,10-phenanthroline (dmp) ligand. The resulting dual species [Cu(II)(dmp)2Cl]+/[Cu(I)(dmp)2]+ electrolyte exhibited an improved lifetime both under full sun and indoor illumination and better regeneration at the counter electrode. Employing this asymmetric dual species Cu(II)/Cu(I) electrolyte with the co-sensitized D35:XY1 dyes, we realized a record PCE of 35.6% under 1000 lux warm white CFL illumination.

Theoretical predictions of the solubilizing capacity of micelles and vesicles present in intestinal fluid are important for the development of new delivery techniques and bioavailability improvement. A balance between accuracy and computational cost is a key factor for an extensive study of numerous compounds in diverse environments. In this study, we aimed to determine an optimal molecular dynamics (MD) protocol to evaluate small-molecule interactions with micelles composed of bile salts and phospholipids. MD simulations were used to produce free energy profiles for three drug molecules (danazol, probucol, and prednisolone) and one surfactant molecule (sodium caprate) as a function of the distance from the colloid center of mass. To address the challenges associated with such tasks, we compared different simulation setups, including freely assembled colloids versus pre-organized spherical micelles, full free energy profiles versus only a few points of interest, and a coarse-grained model versus an all-atom model. Our findings demonstrate that combining these techniques is advantageous for achieving optimal performance and accuracy when evaluating the solubilization capacity of micelles.Graphical abstractAll-atom (AA) and coarse-grained (CG) umbrella sampling (US) simulations and point-wise free energy (FE) calculations were compared to their efficiency to computationally analyze the solubilization of active pharmaceutical ingredients in intestinal fluid colloids.

Nuclear magnetic resonance cryoporometry (NMRC) and differential scanning calorimetry thermoporometry (DSC-TPM) are powerful methods for measuring mesopore size distributions. The methods are based on the fact that, according to the Gibbs–Thomson equation, the melting point depression of a liquid confined to a pore is inversely proportional to the pore size. However, aqueous salt solutions, which inherently exist in a broad range of biological porous materials as well as technological applications such as electrolytes, do not melt at a single temperature. This causes artefacts in the pore size distributions extracted by traditional Gibbs–Thomson analysis of NMRC and DSC-TPM data. Bulk aqueous NaCl solutions are known to have a broad distribution of melting points between the eutectic and pure water phase transition points (252–273 K). Here, we hypothesize that, when aqueous NaCl solution (saline) is confined to a small pore, the whole melting point distribution is shifted toward lower temperatures by the value predicted by the Gibbs–Thomson equation. We show that this so-called shifted phase transition distribution (SIDI) approach removes the artefacts arising from the traditional Gibbs–Thomson analysis and gives correct pore size distributions for saline saturated mesoporous silica gel and controlled pore materials analyzed by NMR cryoporometry. Furthermore, we demonstrate that the method can be used for determining pore sizes in collagen–chondroitin sulphate hydrogels resembling the composition of the extracellular matrix of articular cartilage. It is straightforward to apply the SIDI analysis for DSC-TMP data as well.

The effects of polyethylene glycol- (PEG) modified lipids and gangliosides on the Ca2+ induced interaction between liposomes composed of palmitoyl-oleoyl phosphatidylethanolamine (POPE) and palmitoyl-oleoyl phosphatidylserine (POPS) was investigated at physiological ionic strength. Förster resonance energy transfer (FRET) studies complemented with dynamic light scattering (DLS) and cryo-transmission electron microscopy (Cryo-EM) show that naked liposomes tend to adhere, rupture, and collapse on each other's surfaces upon addition of Ca2+, eventually resulting in the formation of large multilamellar aggregates and bilayer sheets. Noteworthy, the presence of gangliosides or PEGylated lipids does not prevent the adhesion-rupture process, but leads to the formation of small, long-lived bilayer fragments/disks. PEGylated lipids seem to be more effective than gangliosides at stabilizing these structures. Attractive interactions arising from ion correlation are proposed to be a driving force for the liposome-liposome adhesion and rupture processes. The results suggest that, in contrast with the conclusions drawn from previous solely FRET-based studies, direct liposome-liposome fusion is not the dominating process triggered by Ca2+ in the systems studied.

The recently synthesized 4-ethyl-3,5-bis [40-(N, N-diphenylamine)biphenyl-4-yl]-4H-1,2,4-triazole (TPA-TZ) is in this work thoroughly studied as an efficient luminophore with an account of density functional theory. The intense fluorescence is explained as an intramolecular charge-transfer transition from the diphenylamine (donor) moiety to the central part of the dye with a characteristic electron redistribution in the triazole ring (acceptor). The photoluminescence (PL) and phosphorescence (Ph) spectra of TPA-TZ in the film and in THF solution at 77 K were studied together with the well-known 2,4,6-tris [3-(diphenylphosphinyl)phenyl]-1,3,5-triazine (PO-T2T) dye. The latter compound was used as an electron-withdrawing component of the investigated TPA-TZ: PO-T2T exciplex, which is characterized by a relatively high energy level of the excited lowest triplet state. The films of a solid-state mixture of TPA-TZ and PO-T2T showed exciplex-type emission being slightly red-shifted compared to the PL of the individual donor and acceptor compounds. Two OLED devices with emitting layers of TPA-TZ and of the exciplex-forming molecular mixture of TPA-TZ and PO-T2T were prepared. The exciplex-based OLED demonstrated 4 103 cd/m2 brightness, a current efficiency of 22 cd/A, a power efficiency of 6.77 lm/W, and an external quantum efficiency (EQE) of 7%. This confirms the possibility of triplet harvesting in the molecular mixture of TPA-TZ and PO-T2T, since the theoretical EQE limit for OLED based on the prompt fluorescence is 5%.

The thermodynamic properties of four binary mixtures of deep eutectic solvent (DES), i.e., ChCl/Gly (choline chloride + glycerol at a molar ratio of 1:2) and ChCl/EG (choline chloride + ethylene glycol at a molar ratio of 1:2) with two common co-solvents, i.e., dimethyl sulfoxide (DMSO) and isopropanol (IPA), were studied. Density and viscosity were determined at temperatures from 288.15 to 323.15 K, while measuring the enthalpy of mixing was performed at 308.15 and 318.15 K. The volumetric properties (i.e., excess molar volume and excess partial molar volume) and excess viscosities (i.e., viscosity deviation and logarithmic excess viscosity) were further calculated to investigate the effects of temperature, types of co-solvent and DES, and their contents on the non-ideal behavior of these systems, where the influence of treating the DES as a mixture of two components or a pseudo-component was discussed. The results of volumetric properties indicate that the combined influence of packing effects and H-bonding interactions between the DES and co-solvents led to the contraction of mixture volume, and the results of excess viscosities show H-bonding interactions play an important role in their variations. The results of enthalpy of mixing show that the mixing of DES with IPA is endothermic, while the mixing of DES with DMSO is exothermic. Furthermore, the nonrandom two-liquid (NRTL) model and Gibbs-Helmholtz equation were combined to represent the experimental results of the enthalpy of mixing, and the total average relative deviation (ARD) of all studied systems is 5.43%., Validerad;2024;Nivå 2;2024-03-28 (hanlid);Funder: State Key Laboratory of Material-Oriented Chemical Engineering in China; National Natural Science Foundation of China (22011530112);Full text license: CC BY 4.0

The electrochemical and charge storage performance of a fluorine-free structurally flexible hybrid pyrrolidinium-based ionic liquid electrolyte (HILE) in a symmetric graphite-based supercapacitor is thoroughly investigated. The HILE revealed thermal decomposition at above 230°C, a glass transition (Tg) temperature of below −70°C, and ionic conductivity of 0.16 mS cm−1 at 30°C. The chemical and electrochemical properties are investigated using a systematic variable temperature 1H and 31P NMR spectroscopy and diffusometry, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD). The supercapacitor demonstrated a notable specific capacitance of 186 F g−1 at a scan rate of 1 mV s−1 and a specific capacitance of 122 F g−1 at a current density of 0.5 A g−1. The maximum energy density of 48.8 Wh kg−1, a power density of 450 W kg−1 at a current density of 0.5 A g−1, and a potential window of 4 V were obtained. Altogether, this study demonstrates that the new HILE can be used in symmetric graphite-based supercapacitors over a wide potential window of 4 V and a temperature range from −20°C to 90°C., Validerad;2024;Nivå 1;2024-04-04 (signyg)License full text: CC BY-NC-ND 4.0

In this work, ultralow friction (0.054) of graphene was achieved under high contact pressure (1.03 GPa) and atmosphere environment via the operando formation of PbS quantum dots (QDs)/graphene heterojunction at the frictional interface. It is found that PbS QDs are trapped in graphene nanosheets via shear-induced rearrangement for obtaining the PbS QDs/graphene heterojunctions, which provide an excellent rolling effect to lower friction. It is also found that the heterogeneous PbS QDs/graphene tribofilms have a strong Pb-enriched function and heterojunction nanorod phase. Our objective is to uncover the physical and chemical mechanisms governing the friction of 0D/1D nanostructures within PbS QDs/graphene heterostructures through our studies. This research will enhance our comprehension of nanomaterials' frictional behavior while offering valuable guidance and optimization strategies for their application in mechanical engineering and functional nanomaterials. Consequently, our efforts aim to foster the advancement of nanoscience and technology, leading to additional scientific and technological breakthroughs., Validerad;2024;Nivå 2;2024-01-24 (signyg);Funder: National Natural Science Foundation of China (51905295; 52275170); Liaoning Key Laboratory of Aero-engine Materials Tribology (LKLAMTF202304); the Tribology Science Fund of State Key Laboratory of Tribology in Advanced Equipment (SKLTKF21B09; SKLTKF21A04);Full text license: CC BY-4.0

A straightforward and efficient spectrum technique was created using Ortho-chloranil as the electron acceptor (-acceptor) in a charge transfer (CT) complex formation reaction to determine the concentration of famotidine (FMD) in solutions. Compared to the double-distilled blank solution, the reaction result detected a definite violet colour at a maximum absorption wavelength of 546 nm, For concentrations range 2—28 µg/ml, the technique demonstrated excellent compliance with Beer-Law and Lambert's, as evidenced by its molar absorptivity of 2159.648 L mol−1 cm–1. Lower detection limits of 0.3024 µg/ml and 1.471 µg/ml, respectively, were discovered. The complexes of famotidine and Ortho-chloranil were found to have a 2:1 stoichiometry. Additionally, the suggested approach effectively estimated famotidine concentrations in pharmaceutical formulations, particularly in tablet form., Validerad;2024;Nivå 2;2024-03-07 (hanlid);Full text license: CC BY

Excited state molecular dynamics simulations of the photoexcited phenyl azide have been performed. The semi-classical surface hopping approximation has enabled an unconstrained analysis of the electronic and nuclear degrees of freedom which contribute to the molecular dissociation of phenyl azide into phenyl nitrene and molecular nitrogen. The significance of the second singlet excited state in leading the photodissociation has been established through electronic structure calculations, based on multi-configurational schemes, and state population dynamics. The investigations on the structural dynamics have revealed the N−N bond separation to be accompanied by synchronous changes in the azide N−N−N bond angle. The 100 fs simulation results in a nitrene fragment that is electronically excited in the singlet manifold.

Electrochemical water oxidation reaction (WOR) lies among the most forthcoming approaches toward eco-conscious manufacturing of green hydrogen owing to its environmental favors and high energy density values. Its vast commoditization is restricted by high-efficiency and inexpensive catalysts that are extensively under constant research. Herein, calcium, magnesium, and yttrium doped lithium nickel phosphate olivines (LiNi1-xMxPO, LNMP; x = 0.1-0.9; M = Ca2+, Mg2+, and Y3+) were synthesized via non-aqueous sol-gel method and explored for catalytic WOR. Lithium nickel phosphates (LNP) and compositions were characterized via Fourier transform infrared, scanning electron microscopy, X-ray diffraction, and energy dispersive X-ray diffraction techniques for the structural and morphological analyses. Glassy carbon electrode altered with the LNMPs when studied in a standard redox system of 5 mM KMnO4, displayed that yttrium doped LNP, i.e. LNYP-3 exhibits the highest active surface area (0.0050 cm(2)) displaying the lowest average crystallite size (D-avg) i.e. similar to 7 nm. Electrocatalytic behavior monitored in KOH showed that LNMP-2 offers the highest rate constant "k(o)," value, i.e. 3.9 10(-2) cm s(-1) and the largest diffusion coefficient "D-o," i.e. 5.2 x 10(-5) cm(2) s(-1). Kinetic and thermodynamic parameters demonstrated the facilitated electron transfer and electrocatalytic properties of proposed nanomaterials. Water oxidation peak current density values were indicative of the robust catalysis and facilitated water oxidation process besides lowering the Faradic onset potential signifying the transformation of less LNP into more conducive LNMP toward water oxidation.

Rationalizing material features according to the adopted synthetic strategy, aiming then to tune them on demand, is among the most relevant purposes of investigation in materials science. Herein, the systematic analysis of the dependence of graphitic carbon nitride (g-C3N4) physical characteristics on the decomposition temperature of urea, rationalizing the impact of synthetic temperature on several characteristics of the materials (degree of N–H condensation, carbon vs nitrogen content, structural parameters, photoluminescence lifetime, surface area, pores volume), is discussed. g-C3N4 nanostructures are fabricated by thermal decomposition of urea at different temperatures under ambient atmosphere, obtaining an almost ideal stoichiometry (C/N = 0.72) when setting the temperature at 600 °C. The samples show structural, textural, compositional, and optical differences directly depending on the fabrication temperature: specific surface area, pore volume and size, intralayer distance, and speed of radiative recombination of photogenerated charges are proportionally enhanced by increasing the synthesis temperature. The role played by all the physicochemical features of the prepared samples in promoting the catalytic degradation of Rhodamine B is investigated, highlighting their synergistic role in enhancing the catalytic efficiency. Significant differences in the dye degradation are recorded when using either UV or solar simulated light, demonstrating that Rhodamine B photosensitization rules the process., Validerad;2024;Nivå 2;2024-04-23 (joosat);Full text license: CC BY-NC-ND

Solid-state composite electrolytes have arisen as one of the most promising materials classes for next-generation Li-ion battery technology. These composites mix ceramic and solid-polymer ion conductors with the aim of combining the advantages of each material. The ion-transport mechanisms within such materials, however, remain elusive. This knowledge gap can to a large part be attributed to difficulties in studying processes at the ceramic-polymer interface, which are expected to play a major role in the overall ion transport through the electrolyte. Computational efforts have the potential of providing significant insight into these processes. One of the main challenges to overcome is then to understand how a sufficiently robust model can be constructed in order to provide reliable results. To this end, a series of molecular dynamics simulations are here carried out with a variation of certain structural (surface termination and polymer length) and pair potential (van der Waals parameters and partial charges) models of the Li7La3Zr2O12 (LLZO) poly(ethylene oxide) (PEO) system, in order to test how sensitive the outcome is to each variation. The study shows that the static and dynamic properties of Li-ion are significantly affected by van der Waals parameters as well as the surface terminations, while the thickness of the interfacial region - where the structure-dynamic properties are different as compared to the bulk-like regime - is the same irrespective of the simulation setup.

Commercial (protiated) samples of the "green" and biodegradable bioester 2-ethylhexyl laurate (2-EHL) were mixed with D-2-EHL synthesized by hydrothermal deuteration, with the mixtures demonstrating bulk structuring in small-angle neutron scattering measurements. Analysis in a polymer scattering framework yielded a radius of gyration (R (g)) of 6.5 angstrom and a Kuhn length (alternatively described as the persistence length or average segment length) of 11.2 angstrom. Samples of 2-EHL dispersed in acetonitrile formed self-assembled structures exceeding the molecular dimensions of the 2-EHL, with a mean aggregation number (N-agg) of 3.5 +/- 0.2 molecules across the tested concentrations. We therefore present structural evidence that this ester can function as a nonionic (co)-surfactant. The available surfactant-like conformations appear to enable performance beyond the low calculated hydrophilic-lipophilic balance value of 2.9. Overall, our data offer an explanation for 2-EHL's interfacial adsorption properties via self-assembly, resulting in strong emolliency and lubricity for this sustainable ester-based bio-oil., QC 20240223

The inherent colloidal dispersity (due to length, aspect ratio, surface charge heterogeneity) of CNCs, when produced using the typical traditional sulfuric acid hydrolysis route, presents a great challenge when interpreting colloidal properties and linking the CNC film nanostructure to the helicoidal self-assembly mechanism during drying. Indeed, further improvement of this CNC preparation route is required to yield films with better control over the CNC pitch and optical properties. Here we present a modified CNC-preparation protocol, by fractionating and harvesting CNCs with different average surface charges, rod lengths, aspect ratios, already during the centrifugation steps after hydrolysis. This enables faster CNC fractionation, because it is performed in a high ionic strength aqueous medium. By comparing dry films from the three CNC fractions, discrepancies in the CNC self-assembly and structural colors were clearly observed. Conclusively, we demonstrate a fast protocol to harvest different populations of CNCs, that enable tailored refinement of structural colors in CNC films., QC 20240201

Catalytic reactions on solid surfaces have been studied under Ultra-high vacuum (UHV) conditions for decades. These studies provide crucial information for catalytic reactions, such as surface structures, adsorption sites, and reaction mechanisms. However, industrial catalysis operates under high gas pressure to increase the reaction rate, so the knowledge we learn from the previous UHV studies may not be able to directly transfer to the industry. This difference is referred to as the “pressure gap”, and it represents the difficulties that scientists encounter when attempting to investigate and comprehend catalytic reactions at high pressure. To address this issue, in situ/operando techniques and instruments have been developed to study reactions at pressures closer to real-world applications.The present thesis aims to showcase the new instrument, Near-Ambient Pressure Velocity Map Imaging (NAP-VMI), and its applications to molecular spectroscopy and surface science at near-ambient pressures. This instrument features a velocity map imaging (VMI) setup with redesigned ion optics and uses differential pumping to achieve a working pressure of 10−3 mabr. It allows time-resolved measurements at microsecond time scales using the pump-probe technique with a pulsed molecular beam and a pulsed laser. The performance is validated using N2O photodissociation and N2 surface scattering. CO oxidation on Pd(110) and Pd(100) surfaces is studied at elevated oxygen pressure (1×10−5 mbar) where the surfaces reconstruct.The results show the suppression of CO2 production in oxygen rich environments for both surfaces. The difference in kinetics and dynamics behavior between the two surfaces also suggests that surface structures and adsorption sites are important in the reaction mechanisms. These findings highlight the importance of surface structure in catalytic reactions and pave the way for more effective catalysts to be designed by tailoring surface properties and reaction conditions., Katalytiska reaktioner på fasta ytor har studerats under ultrahögt vakuum (UHV) i årtionden. Dessa studier ger avgörande information för katalytiska reaktioner, såsom ytstrukturer, adsorptionsställen och reaktionsmekanismer. Industriell katalys arbetar dock under högt gastryck för att öka reaktionshastigheten, så kunskapen vi lär oss från de tidigare UHV-studierna kanske inte direkt kan överföras till industrin. Denna skillnad kallas “tryckgapet” och den representerar de svårigheter som forskare möter när de försöker undersöka och förstå katalytiska reaktioner vid högt tryck. För att lösa detta problem har in situ/operando metoder och instrument utvecklats för att studera reaktioner vid tryck som ligger närmare verkliga tillämpningar. Den föreliggande avhandlingen syftar till att visa upp det nya instrumentet, nära-omgivande tryckhastighetskarta-avbildning (NAP-VMI) och dess tillämpningar för molekylär spektroskopi och ytvetenskap vid nära-omgivande tryck. Detta instrument har en hastighetskarta-avbildning (VMI) med omdesignadjonoptik och använder differentialpumpning för att uppnå ett arbetstryckpå 10−3 mabr. Den tillåter tidsupplösta mätningar på mikrosekunders tidsskalormed hjälp av pump-probe-teknik med pulsmolekylär stråle och pulslaser. Prestandan valideras med hjälp av N2O fotodissociation och N2 ytspridning. CO oxidation på Pd(110) och Pd(100) ytan studeras vid förhöjt syretryck (1 × 10−5 mbar) där ytorna rekonstrueras. Resultaten visar undertryckandet av CO2 produktion i syrerika miljöer för båda ytorna. Skillnaden i kinetik och dynamikbeteende mellan de två ytorna tyder också på att ytstrukturer och adsorptionsställen är viktiga i reaktionsmekanismerna. Dessa fynd framhäver vikten av ytstruktur i katalytiska reaktioner och banar väg för mer effektiva katalysatorer som kan utformas genom att skräddarsy ytegenskaper och reaktionsförhållanden., QC 20240117

Given the potential of ionic liquids (ILs) for batteries, supercapacitors and advanced lubricants, it is crucial to understand how electric fields affect the interfacial behaviour in IL-solvent systems and the intricate relationship between nanostructure and tribotronic properties. This thesis investigates the structural and compositional changes of ILs with different solvents at electrified interfaces. The four papers constituting this thesis can be broadly divided into two studies. The first study outlines the electro-interfacial behaviour of various monocationic (MILs) and dicationic ILs (DILs) dispersed in propylene carbonate. Combining electrochemical quartz crystal microbalance, neutron reflectivity (EC-NR), and atomic force microscopy, a voltage-induced interphase transition from a self-assembled cation bilayer to a conventional electrical double-layer structure has been revealed in bis(oxalato)borate anion MILs. This interphase transition has not been observed in DILs, attributed to the dual charge centres reducing the segregation between polar and apolar domains of dications for self-assembly interaction. The second study explores three MILs sharing the same phosphonium cation with varying orthoborate-based anions dissolved in 2-ethylhexyl laurate (2-EHL). EC-NR measurements reveal a solvent-rich interfacial corona layer and the subtlety of anion architecture in tuning electro-interfacial properties. Meanwhile, EC-NR has been used as a complementary probe to elucidate the nano-scale structural and compositional changes in the boundary films of IL/2-EHL systems with varying potentials, providing a direct link between the molecular controllability and macroscopic tribotronic performance studies. This thesis contributes to the fundamental understanding of electro-interfacial behaviour and controllability of IL-solvent systems and offers valuable molecular insights for deploying these novel ILs as additives in advanced tribological and electrochemical contexts, Med tanke på potentialen hos jonvätskor (IL) för batterier, superkondensatorer och avancerade smörjmedel är det viktigt att förstå hur elektriska fält påverkar gränsytans beteende i IL-lösningsmedelssystem och det intrikata förhållandet mellan nanostrukturer och tribotroniska egenskaper. Denna avhandling undersöks strukturella och kompositionella förändringar av ILs med olika lösningsmedel vid elektrifierade gränssnitt. Avhandlingen baseras på fyra artiklar och kan grovt delas i två bredare studier. Den första studien beskriver det elektro-interfaciala beteendet hos olika monokatjoniska (MILs) och dikatjoniska ILs (DILs) dispergerade i propylenkarbonat. Kombinationen av elektrokemisk kvartskristallmikro-balans, neutronreflektivitet (EC-NR) och atomkraftsmikroskopi har lett till avslöjandet av en spänningsinducerad fasövergång från ett självassocierad katjonbilager till en konventionell elektrisk dubbelskiktsstruktur i MIL med bis(oxalato)boratanjon. Denna interfasövergång har inte observerats i DILs, vilket tillskrivs de dubbla laddningscentra som minskar segregeringen mellan polära och apolära domäner av dikationer för självassoceringsinteraktion. Den andra studien undersöker tre MIL som delar samma fosfoniumkatjon med olika ortoboratbaserade anjoner löst i 2-etylhexyllaurat (2-EHL). EC-NR-mätningar avslöjar ett lösningsmedelsrikt korona-skikt i gränsytan och hur anjonarkitekturen påverkar de elektro-interfaciala egenskaperna. Samtidigt har EC-NR belyst de nanoskaliga strukturella och kompositionella förändringarna i gränsskikten i IL/2-EHL-system med varierande potentialer, vilket ger en direkt koppling av den molekylära styrbarheten och makroskopiska tribotroniska prestandan. Denna avhandling bidrar till den grundläggande förståelsen av elektro-interfacial beteende och styrbarhet hos IL-lösningsmedelssystem och erbjuder värdefulla molekylära insikter för att använda dessa nya IL som tillsatser i avancerade tribologiska och elektrokemiska sammanhang., QC 20240112

Understanding the processes guiding the confinement of adsorbed H2 in different porous structures is vital for the development of adsorbents for effective cryo-adsorptive H2 storage systems. Quasi-elastic neutron scattering (QENS) is applied over a wide range of timescales (0.2 ps – 150 ps) to determine different self-diffusion mechanisms of H2 adsorbed in a carbide (synthesized from TiC via the sol-gel method) derived carbon (sol-gel TiC-CDC) adsorbent with hierarchical porous structure. The bulk and porous structure is characterized by gas adsorption, Raman spectroscopy, and wide-angle X-ray scattering methods. Sol-gel TiC-CDC belongs to a series of CDCs that have been previously characterized and where the self-diffusion of adsorbed H2 has been investigated with QENS. Sol-gel TiC-CDC is very mesoporous, has relatively high stacking (2.76 graphenic layers per stack), and small interlayer spacing of graphenic sheets (3.43 Å) in comparison to other CDCs in the series, thus, being a well-ordered highly porous CDC. Restricted rotational self-diffusion of adsorbed H2 is determined in ultramicropores (pore width, w, < 7 Å) and translationally self-diffusing H2 adsorbed in multilayers across multiple timescales are determined in micro- and mesopores (7 Å < w < 500 Å). The microporous and graphenic structure of the CDC does not remarkably affect the self-diffusion of H2 at high surface coverages. The simultaneous determination of adsorbed H2 motions across different timescales allows to analyze the influence of micro- and mesopores under H2 loading conditions, which are close to the ones used in technical applications and are vital for adsorbent optimization., QC 20240130

Bismuth telluride-Bi2Te3 is the most promising material for harvesting thermal energy near room temperature. There are numerous works on Bi2Te3 reporting significantly different transport properties, with no clear connection to the synthetic routes used and the resultant surface chemistry of the synthesized materials. It is of utmost importance to characterize the constituent particles’ surface and interfaces to get a better understanding of their influence on the transport properties, that will significantly improve the material design starting from the synthesis step. Electrophoretic deposition (EPD) is a promising technique, enabling the formation of thick films using colloidally stabilized suspensions of pre-made nanoparticles, which can enable the study of the effect of surface chemistry, in connection to the synthetic route, on the material's transport properties. In order to explore the differences in surface chemistry and the resultant transport properties in relation to the synthetic scheme used, here we report on Bi2Te3 synthesised through two wet-chemical routes in water (Hydro-) and oil (Thermo-) as the solvents. XRD analysis showed a high phase purity of the synthesized materials. SEM analysis revealed hexagonal platelet morphology of the synthesized materials, which were then used to fabricate EPD films. Characterization of the EPD films reveal significant differences between the Hydro- and Thermo-Bi2Te3 samples, leading to about 8 times better electrical conductivity values in the Thermo-Bi2Te3. XPS analysis revealed a higher metal oxides content in the Hydro-Bi2Te3 sample, contributing to the formation of a resistive layer, thus lowering the electrical conductivity. Arrhenius plots of electrical conductivity vs inverse temperature was used for the estimation of the activation energy for conduction, revealing a higher activation energy need for the Hydro-Bi2Te3 film, in agreement with the resistive barrier oxide content. Both the samples exhibited neg, QC 20231227

Hypothesis: Aqueous graphene dispersions are usually obtainable by treating the surface of graphene chemically or physically. In these dispersions, the rheological properties (e.g., viscosity) are governed by a direct coupling to the graphene concentration, which limits their applicability. An alternative approach for dispersing graphene is trapping them in a viscoelastic-network formed by a co-dispersed charged fibrous-clay, Sepiolite. Contrary to surface treatment, the rheological properties of these dispersions are set by the clay particles. The rheology of charged-colloidal dispersions is governed by various parameters, including interparticle interactions. Hence, the rheology of the dispersion could be modulated by changing the clay surface charge without compromising the dispersed graphene concentration. Experimental: The surface charge of Sepiolite was modulated either by charge-screening (by NaCl added to the solution) or by surface-charging (by attachment of highly charged ions, e.g., HexaMetaPhosphate, HMP−) and the effect on rheology and graphene concentration was assessed. In particular, loading the dispersion with HMP− yielded low viscosity, storage, and loss moduli (two orders of magnitude lower than the corresponding HMP−-free dispersion) while the graphene concentration was maintained. We demonstrate that by this charge-modulation approach, reaching the rheological requirements of different applications without compromising on graphene concentration is plausible., QC 20231218

Optimization of boundary lubrication by tuning the confined molecular structures formed by surface-active additives such as surfactants and polymers is of key importance to improving energy efficiency in mechanical processes. Here, using the surface forces apparatus (SFA), we have directly measured the normal and shear forces between surface layers of a functionalised olefin copolymer (FOCP) in n-dodecane, deposited onto mica using the Langmuir-Blodgett (LB) technique. The FOCP has an olefin backbone decorated with a statistical distribution of polar-aromatic groups, with a structure that we term as "centipede". The effect of lateral confinement, characterised by the surface pressure, Pi(dep), at the air-water interface at which the LB films are transferred, was examined. Normal force profiles revealed that the thickness of the LB films increased significantly with Pi(dep), with the film thickness (t > 20 nm) inferring a multi-layered film structure, consistent with the interfacial characterisation results from synchrotron X-ray reflectivity (XRR) measurements. The coefficient of friction, mu, between the LB films spanned two orders of magnitude from superlubricity (mu similar to 0.002) to much higher friction (mu > 0.1) depending nonlinearly on Pi(dep), with the lowest friction observed at the intermediate Pi(dep). Molecular arrangement upon LB compression leads to the multilayer film with a structure akin to an interfacial gel, with transient crosslinking facilitated by the intra- and inter-molecular interactions between the functional groups. We attribute the differences in frictional behaviour to the different prevalence of the FOCP functional groups at the lubricating interface, which depends sensitively on the degree of compression at the air-water interface prior to the LB deposition. The LB films remain intact after repeated compression (up to pressures of 10 MPa) and shear cycles, indicating strong surface anchorage and structural robustness as a load, QC 20231128

The rational design of elemental incorporation in colloidal eco-friendly core/shell quantum dots (QDs) holds the potential to synergistically tailor their electronic band structure and carrier kinetics for applications in forthcoming “green” and high-efficiency solar energy conversion. Herein, we have conducted simultaneous Cu incorporation in both the core and shell regions of environment-benign AgInSe (AISe)/ZnSe core/shell QDs to realize high-efficiency solar-driven photoelectrochemical (PEC) hydrogen evolution. It is verified that Cu incorporation in AISe core enables an upward shift in the position of the band edge relative to the ZnSe shell, which promoted the electron delocalization and extended the lifetime of exciton. Simultaneously, Cu incorporation in the ZnSe shell further results in the trapping of photoinduced holes from AISe core, leading to a decelerated recombination of carriers. The prepared Cu-AISe/ZnSe:Cu QDs with optimized optoelectronic properties have been successfully employed to fabricate QDs-PEC devices, delivering a maximum photocurrent density of 9.1 mA cm−2 under standard AM 1.5 G illumination (100 mW cm−2). Our findings indicate that synchronous elemental incorporation in eco-friendly core/shell QDs is a promising strategy to achieve future high-performance solar-to-hydrogen conversion systems., Validerad;2024;Nivå 2;2024-02-05 (joosat);Funder: Sichuan Science and Technology Program (2021YFH0054, 2023JDGD0011); National Natural Science Foundation of China (22105031); National Key Research and Development Program of China (2019YFE0121600); Fundamental Research Funds for the Central Universities (2019YFB2203400, ZYGX2020J028); 111 Project (B20030); H2020 Framework program through PNRR iNEST and NEST projects; Ca’ Foscari University of Venice;Full text license: CC BY

We theoretically propose a multidimensional high-harmonic echo spectroscopy technique which utilizes strong optical fields to resolve coherent electron dynamics spanning an energy range of multiple electronvolts. Using our recently developed semi-perturbative approach, we can describe the coherent valence electron dynamics driven by a sequence of phase-matched and well-separated short few-cycle strong infrared laser pulses. The recombination of tunnel-ionized electrons by each pulse coherently populates the valence states of a molecule, which allows for a direct observation of its dynamics via the high harmonic echo signal. The broad bandwidth of the effective dipole between valence states originated from the strong-field excitation results in nontrivial ultra-delayed partial rephasing echo, which is not observed in standard two-dimensional optical spectroscopic techniques in a two-level molecular systems. We demonstrate the results of simulations for the anionic molecular system and show that the ultrafast valence electron dynamics can be well captured with femtosecond resolution.

Protons in low-barrier superstrong hydrogen bonds are typically delocalized between two electronegative atoms. Conventional methods to characterize such superstrong hydrogen bonds are vibrational spectroscopy and diffraction techniques. We introduce soft X-ray spectroscopy to uncover the electronic fingerprints for proton sharing in the protonated imidazole dimer, a prototypical building block enabling effective proton transport in biology and high-temperature fuel cells. Using nitrogen core excitations as a sensitive probe for the protonation status, we identify the X-ray signature of a shared proton in the solvated imidazole dimer in a combined experimental and theoretical approach. The degree of proton sharing is examined as a function of structural variations that modify the shape of the low-barrier potential in the superstrong hydrogen bond. We conclude by showing how the sensitivity to the quantum distribution of proton motion in the double-well potential is reflected in the spectral signature of the shared proton.

Magnesium clusters exhibit a pronounced nonmetal-to-metal transition, and the neutral dimer is exceptionally weakly bound. In the present study, we formed pristine Mgnz+ (n = 1–100, z = 1–3) clusters and mixed (C60)mMgnz+ clusters (m = 1–7, z = 1, 2) upon electron irradiation of neutral helium nanodroplets doped with magnesium or a combination of C60 and magnesium. The mass spectra obtained for pristine magnesium cluster ions exhibit anomalies, consistent with previous reports in the literature. The anomalies observed for C60Mgn+ strongly suggest that Mg atoms tend to wet the surface of the single fullerene positioning itself above the center of a pentagonal or hexagonal face, while, for (C60)mMgnz+, the preference for Mg to position itself within the dimples formed by fullerene cages becomes apparent. Besides doubly charged cluster ions, with the smallest member Mg22+, we also observed the formation of triply charged ions Mgn3+ with n > 24. The ion efficiency curves of singly and multiply charged ions exhibit pronounced differences compared to singly charged ions at higher electron energies. These findings indicate that sequential Penning ionization is essential in the formation of doubly and triply charged ions inside doped helium nanodroplets.

There are several difficulties when experimentally determined reaction mechanisms are applied from model systems to real catalysis. Besides the infamous pressure and material gaps, it is sometimes necessary to consider impurities in the real reactant feedstock that can act as promoters or catalyst poisons and alter the reaction path. In this study, the effect of sulfur on the dehydrogenation of naphthalene on Ni(111) is investigated by using X-ray photoelectron spectroscopy and scanning tunneling microscopy. Sulfur induces a (5√3 × 2) surface reconstruction, as previously reported in the literature. The sulfur does not have a strong effect on the dehydrogenation temperature of naphthalene. However, the presence of sulfur leads to a preferred formation of carbidic over graphitic carbon and a strong inhibition of carbon diffusion into the nickel bulk, which is one of the steps of destructive whisker carbon formation described in the catalysis literature.

Photochemically prepared transition-metal complexes are known to be effective at cleaving the strong C–H bonds of organic molecules in room temperature solutions. There is also ample theoretical evidence that the two-way, metal to ligand (MLCT) and ligand to metal (LMCT), charge-transfer between an incoming alkane C–H group and the transition metal is the decisive interaction in the C–H activation reaction. What is missing, however, are experimental methods to directly probe these interactions in order to reveal what determines reactivity of intermediates and the rate of the reaction. Here, using quantum chemical simulations we predict and propose future time-resolved valence-to-core resonant inelastic X-ray scattering (VtC-RIXS) experiments at the transition metal L-edge as a method to provide a full account of the evolution of metal–alkane interactions during transition-metal mediated C–H activation reactions. For the model system cyclopentadienyl rhodium dicarbonyl (CpRh(CO)2), we demonstrate, by simulating the VtC-RIXS signatures of key intermediates in the C–H activation pathway, how the Rh-centered valence-excited states accessible through VtC-RIXS directly reflect changes in donation and back-donation between the alkane C–H group and the transition metal as the reaction proceeds via those intermediates. We benchmark and validate our quantum chemical simulations against experimental steady-state measurements of CpRh(CO)2 and Rh(acac)(CO)2 (where acac is acetylacetonate). Our study constitutes the first step towards establishing VtC-RIXS as a new experimental observable for probing reactivity of C–H activation reactions. More generally, the study further motivates the use of time-resolved VtC-RIXS to follow the valence electronic structure evolution along photochemical, photoinitiated and photocatalytic reactions with transition metal complexes.

Organic hole-transporting materials (HTMs) are of importance in the progress of new-generation photovoltaics, notably in perovskite solar cells (PSCs), solid-state dye-sensitized solar cells (sDSCs), and organic solar cells (OSCs). These materials play a vital role in hole collection and transportation, significantly impacting the power conversion efficiency (PCE) and overall stability of photovoltaic devices. The emergence of spiro(fluorene-9,9 '-xanthene) (SFX) as a novel building block for organic HTMs has gained considerable attention in the field of photovoltaics. Its facile one-pot synthetic approach, straightforward purification, and physiochemical properties over the prototype HTM spiro-OMeTAD have positioned SFX as a highly attractive alternative. In this Account, we present a comprehensive and in-depth summary of our research work, focusing on the advancements in SFX-based organic HTMs in photovoltaic devices with a particular emphasis on PSCs and sDSCs. Several key objectives of our research have been focused on exploring strategies to improve the properties of SFX-based HTMs. (i) One of the critical aspects we have addressed is the improvement of film quality. By carefully designing the molecular structure and employing suitable synthetic approaches, we have achieved HTMs with excellent film-forming ability, resulting in uniform and smooth films over large areas. This achievement is pivotal in ensuring the reproducibility and efficiency of photovoltaic devices. Furthermore, (ii) our investigations have led to an improvement in hole mobility within the HTMs. Through molecular engineering, such as increasing the molecular conjugation and introducing multiple SFX units, we have demonstrated enhanced charge-carrier mobility. This advancement plays a crucial role in minimizing charge recombination losses and improving the overall device efficiency. Additionally, (iii) we have explored the concept of defect passivation in SFX-based HTMs. By incorporating Lewis

In this study, we investigated the self-ordering process in Langmuir films of polydisperse iron oxide nanoparticles on a water surface, employing in situ x-ray scattering, surface pressure-area isotherm analysis, and Brewster angle microscopy. X-ray reflectometry confirmed the formation of a monolayer, while grazing incidence small-angle x-ray scattering revealed short-range lateral correlations with a characteristic length equal to the mean particle size. Remarkably, our findings indicated that at zero surface pressure, the particles organized into submicrometer clusters, merging upon compression to form a homogeneous layer. These layers were subsequently transferred to a solid substrate using the Langmuir-Schaefer technique and further characterized via scanning electron microscopy and polarized neutron reflectometry. Notably, our measurements revealed a second characteristic length in the lateral correlations, orders of magnitude longer than the mean particle diameter, with polydisperse particles forming circular clusters densely packed in a hexagonal lattice. Furthermore, our evidence suggests that the lattice constant of this mesocrystal depends on the characteristics of the particle size distribution, specifically the mean particle size and the width of the size distribution. In addition, we observed internal size separation within these clusters, where larger particles were positioned closer to the center of the cluster. Finally, polarized neutron reflectometry measurements provided valuable insights into the magnetization profile across the layer.

Naphthalimide derivatives composed of donor-acceptor type structures hold significant promise across a wide range of applications. Here, the solvent polarity and viscosity controlled excited-state dynamics of a naphthalimide derivative with a donor-acceptor structure were studied using multiple spectroscopic techniques. From the stationary spectroscopic investigations, large Stokes shift and low fluorescence quantum yield were observed with increasing the solvent polarity, suggesting a more polar excited state relative to the ground state, which is evidenced by the Lippert-Mataga relationship. We also observe an enhanced fluorescence with a prolonged lifetime in a more viscous solution due to the restriction of excited-state molecular rearrangement. These observations result from the emerged twisted intramolecular charge transfer (TICT) state. The ultrafast spectroscopy studies further unravel a solvent polarity dependent excited state evolution from the intramolecular charge transfer state to the TICT state, revealing that the TICT state can be populated only in strong polar solvents. Control experiments by tuning the solvent viscosity in ultrafast experiments were employed to verify the excited state molecular rearrangement subsequently. These observations collectively emphasize how fine-tuning the photophysical properties of naphthalimide derivatives can be achieved through strategic manipulation of solvent polarity and viscosity. The TICT mechanism of naphthalimide derivative was investigated by ultrafast spectroscopy, unraveling the dielectronic constant controlled excited state evolution from LE/ICT to the TICT state accompanied by the molecular rearrangement.

The field of polariton chemistry studies molecules strongly coupled to the light field of optical cavities. The resulting modification of the potential energy landscape has been shown to allow control of the chemical and physical properties of materials and molecular ensembles. In this work, we have studied the theoretical description of molecules interacting with the vacuum field of an optical cavity, derived from the Pauli-Fierz Hamiltonian. We extend the molecular Tavis-Cummings model to include coupling terms arising from the static dipole moments that are present in molecules as well as the dipole self-energy. Since this representation complicates the distinction between photon and matter degrees of freedom, a transformation to the coherent state basis is required. To verify the importance of these additional coupling terms in the molecular model, we simulated the excited state dynamics and spectroscopy of MgH+ molecules resonantly coupled to a cavity vacuum mode. We observe a significant difference in the dynamics when the interaction terms are included individually, compared to a naive molecular Tavis-Cummings model. A reduced effect is obtained when a combined contribution is considered, indicating that considering both terms is essential in the system description. In addition, a strong asymmetry in the spectrum is observed, which can be explained as an influence of the vibrational states and the molecular Franck-Condon factors. To make the analysis of large ensembles computationally accessible, we developed an effective model which is based on a two-level system model.

Electrochemical water splitting powered by renewable energy sources hold potential for clean hydrogen production. However, there is still persistent challenges such as low solar-to-hydrogen conversion efficiency and sluggish oxygen evolution reactions. Here, we address the poor kinetics by studying and strengthening the coupling between Ce and W, and concurrently establishing Ce-W bi-atomic clusters on P,N-doped carbon (WN/WC-CeO2−x@PNC) with a “treasure-bowl” style. The bifunctional active sites are established using a novel and effective self-sacrificial strategy involving in situ induced defect formation. In addition, by altering the coupling of the W(d)-N(p) and W(d)-Ce(f) orbitals in the WN/WC-CeO2−x supramolecular clusters, we are able to disrupt the linear relationship between the binding energies of reaction intermediates, a key to obtain high catalytic performance for transition metals. Through the confinement of the WN/WC-CeO2−x composite hetero-clusters within the sub-nanometre spaces of hollow nano-bowl-shaped carbon reactors, a stable and efficient hydrogen production via water electrolysis could be achieved. When assembled together with a solar GaAs triple junction solar cell, a solar-to-hydrogen conversion efficiency of 18.92% in alkaline media could be realized. We show that the key to establish noble metal free catalysts with high efficiency lies in the fine-tuning of the metal-metal interface, forming regions with near optimal adsorption energies for the reaction intermediates participating in water electrolysis.

The Mn4CaO5(6) cluster in photosystem II catalyzes water splitting through the Si state cycle (i = 0-4). Molecular O2 is formed and the natural catalyst is reset during the final S3 → (S4) → S0 transition. Only recently experimental breakthroughs have emerged for this transition but without explicit information on the S0-state reconstitution, thus the progression after O2 release remains elusive. In this report, our molecular dynamics simulations combined with density functional calculations suggest a likely missing link for closing the cycle, i.e., restoring the first catalytic state. Specifically, the formation of closed-cubane intermediates with all hexa-coordinate Mn is observed, which would undergo proton release, water dissociation, and ligand transfer to produce the open-cubane structure of the S0 state. Thereby, we theoretically identify the previously unknown structural isomerism in the S0 state that acts as the origin of the proposed structural flexibility prevailing in the cycle, which may be functionally important for nature's water oxidation catalysis.

Gelation of protein condensates formed by liquid-liquid phase separation occurs in a wide range of biological contexts, from the assembly of biomaterials to the formation of fibrillar aggregates, and is therefore of interest for biomedical applications. Soluble-to-gel (sol-gel) transitions are controlled through macroscopic processes such as changes in temperature or buffer composition, resulting in bulk conversion of liquid droplets into microgels within minutes to hours. Using microscopy and mass spectrometry, we show that condensates of an engineered mini-spidroin (NT2repCTYF) undergo a spontaneous sol-gel transition resulting in the loss of exchange of proteins between the soluble and the condensed phase. This feature enables us to specifically trap a silk-domain-tagged target protein in the spidroin microgels. Surprisingly, laser pulses trigger near-instant gelation. By loading the condensates with fluorescent dyes or drugs, we can control the wavelength at which gelation is triggered. Fluorescence microscopy reveals that laser-induced gelation significantly further increases the partitioning of the fluorescent molecules into the condensates. In summary, our findings demonstrate direct control of phase transitions in individual condensates, opening new avenues for functional and structural characterization.

The development of p–n tandem dye-sensitized solar cells (t-DSCs) offers the potential for substantial open-circuit voltages, holding great promise for a wide range of applications, particularly in the fields of photovoltaics and photoelectrochemical devices. Most reported t-DSCs are liquid-based, and suffer from unsatisfactory stability due to the leakage of liquid electrolytes and photovoltage that is limited to the energy difference of the two utilized semiconductors. In this study, we present the first realization of a solid-state p–n tandem dye-sensitized solar cell that incorporates both p-type and n-type solid-state dye-sensitized solar cells (ssDSCs) by using a transparent indium-doped tin oxide (ITO) back contact for both sides. Notably, this tandem system shows a remarkable open-circuit voltage of 1.4 V, surpassing the constraints of its liquid-based counterparts. Although the performance variations between p-ssDSCs and n-ssDSCs hint at challenges related to charge recombination and the efficiency of p-ssDSCs, this study underscores the significant potential inherent in solid-state tandem configurations.

Proteins are one of the fundamental building blocks of life as we know it. They are central to various biological processes and pivotal parts of essential procedures in the healthcare, food and sustainability industries. Over the past few years, significant research efforts have been made to employ bio-based strategies as alternative pathways to shift away from human dependency on petroleum-based polymers, placing protein as central building blocks for sustainable material development. In this framework, this thesis explores a specific class of material building blocks derived from the food we eat, referred to as protein nanofibrils (PNFs). Particular attention is paid to PNFs from soy protein isolate (SPI) and whey protein isolate (WPI) formed at low pH and high temperature, mirroring processes commonly found in food processing and cooking. The presented work focuses explicitly on how these fibrils assemble from acid hydrolysis of the initial food proteins into smaller aggregation-prone species, how aggregation occurs and how we can potentially process fibrils as valuable materials for society. A critical step in forming fibrils at low pH and high temperature is the heat-induced acid hydrolysis of protein chains into shorter peptides. The work first uses SPI as a model protein source to understand PNF formation. By determining the activation energy for SPI hydrolysis and comparing it with the lower activation energies for the aggregation processes of one of the peptide building blocks, BB2, we establish that hydrolysis is the with the highest energy of activation. Computer simulations are then employed to replicate the hydrolysis of proteins to model peptide production and degradation from rates of protein hydrolysis. With this, a connection between monomer production and fibrillation kinetics can be established. With this, numerical simulations of BB2 at 90 °C and pH two are then attempted, demonstrating that aggregation of this peptide alone does not replicate, Proteiner är några av de fundamentala byggstenarna för livet som vi känner det, centrala inte bara för variation av biologiska processer men även som avgörande delar av viktiga procedurer inom hälso-, livsmedels- och hållbarhetsindustrier. De senaste åren har stora forskningsinsatser genomförts för att använda bio-baserade strategier som alternativa vägar för att minska det mänskliga beroendet i petroleumbaserade polymerer, och istället placera proteiner som centrala byggstenar för hållbar materialutveckling. Denna avhandling utforskar, enligt detta ramverk, en specifik klass av materielbyggstenar som härstammar från maten vi äter, även kända som protein-nanofibriller (PNF). Särskild uppmärksamhet riktas mot PNF:er från sojaproteinisolat (SPI) och vassleproteinisolat (WPI) bildade vid lågt pH-värde och hög temperatur, vilket speglar vanligt förekommande processer vid livsmedelsbearbetning och matlagning. Det presenterade arbetet fokuserar specifikt på hur dessa fibriler sammansätts genom hydrolys under sura förhållanden ur de initiala livsmedelsproteinerna till små aggregeringssbenägna peptider, hur aggreggation sker samt hur vi potentiellt skulle kunna bereda fibriller som användbara material ute i samhället. Ett kritiskt steg i formandet av fibriller vid lågt pH-värde och hög temperatur är den värmeinducerade sura hydrolysen av proteinkedjor till kortare peptider. SPI används som en modellproteinkälla för att förstå PNF-formering. Genom att fastställa aktiveringsenergin för SPI-hydrolys och jämföra den med de lägre aktiveringsenergierna för aggregationsprocesserna för en av peptidbyggstenarna, BB2, kan det fastslås att hydrolysen är processen med den högsta aktiveringsenergin. Datorsimulationer genomförs sedan för att reproducera hydrolysen av proteiner till modellpeptidproduktion och nedbrytning från olika hastigheter av proteinhydrolys. Därmed kan en koppling mellan monomerproduktion och fibrillationskinetik etableras. Med detta görs ett försök med numersiska, Proteínas são moléculas orgânicas essenciais à vida e elementos centrais em inúmeros processos biológicos e industriais. Nos últimos anos, têm sido realizados esforços significativos no âmbito da investigação e desenvolvimento de estratégias para reduzir a dependência humana de polímeros à base de petróleo. Assim sendo, proteínas surgem como blocos de construção centrais para o desenvolvimento de materiais sustentáveis. Neste sentido, a presente tese de doutoramento tem como foco principal explorar a formação e utilização de proteínas nanofibrilares (PNFs), também designados de amilóides artificiais, como unidades de construção de nanomateriais. Especificamente, a tese explora a formação de PNFs a partir da hidrólise de proteínas alimentares. Neste caso, a formação de PNFs é precedida pela hidrólise das proteínas na sua forma nativa que, em termos simples, "corta" as proteínas em segmentos mais pequenos, designados de péptidos. Do vasto número de péptidos formados durante a hidrólise de proteínas, uma parte terá propensão para posteriormente se agregarem e formarem PNFs. Estas podem ter várias aplicações práticas, tais como o desenvolvimento de biomateriais para a sociedade e com utilidade pública. A pesquisa examina, particularmente, PNFs feitas a partir de isolado de proteína de soja (SPI) e isolado de proteína de soro de leite, também conhecido como whey protein (WPI). Estas PNFs são formadas em condições de pH baixo e alta temperatura. Tal estratégia é bastante comum no processamento de produtos nas indústrias alimentares e farmacêuticas. Inicialmente, esta tese explora a utilização de SPI como proteína-modelo para investigar a formação de PNFs. Ao determinar a energia de ativação relacionada com a hidrólise ácida de SPI, usando a lei de Arrhenius, comparando-a com as energias de ativação referentes aos processos de agregação de um dos blocos de construção peptídicos das fibras da soja, BB2, é estabelecido que a hidrólise é o processo que requer maior energia, QC 20240927

Strong coupling of organic molecules to the vacuum field of a nanoscale cavity can be used to modify their chemical and physical properties. We extend the Tavis–Cummings model for molecular ensembles and show that the often neglected interaction terms arising from the static dipole moment and the dipole self-energy are essential for a correct description of the light–matter interaction in polaritonic chemistry. On the basis of a full quantum description, we simulate the excited-state dynamics and spectroscopy of MgH+ molecules resonantly coupled to an optical cavity. We show that the inclusion of static dipole moments and the dipole self-energy is necessary to obtain a consistent model. We construct an efficient two-level system approach that reproduces the main features of the real molecular system and may be used to simulate larger molecular ensembles.

Bandgap tunability of lead mixed halide perovskites (LMHPs) is a crucial characteristic for versatile optoelectronic applications. Nevertheless, LMHPs show the formation of iodide-rich (I-rich) phase under illumination, which destabilizes the semiconductor bandgap and impedes their exploitation. Here, it is shown that how I-2, photogenerated upon charge carrier trapping at iodine interstitials in LMHPs, can promote the formation of I-rich phase. I-2 can react with bromide (Br-) in the perovskite to form a trihalide ion I2Br- (I delta--I delta+-Br delta-), whose negatively charged iodide (I delta-) can further exchange with another lattice Br- to form the I-rich phase. Importantly, it is observed that the effectiveness of the process is dependent on the overall stability of the crystalline perovskite structure. Therefore, the bandgap instability in LMHPs is governed by two factors, i.e., the density of native defects leading to I-2 production and the Br- binding strength within the crystalline unit. Eventually, this study provides rules for the design of chemical composition in LMHPs to reach their full potential for optoelectronic devices., Funding Agencies|ERC; European Unions Horizon 2020 research and innovation programme via the MSCA-IF [839480, 101023689, MSCA-ITN SMART-X, 860553]; European Unions HOrizon Europe reserach and innovation programme [101082176-VALHALLA]; Netherlands Ministry of Education, Culture and Science [024.001.035]; Netherlands Organization for Scientific Research via a Spinoza grant; [771528]

As a new class of organic photocatalysts, polymer dots show a potential application in photocatalytic hydrogen peroxide production coupled with chemical oxidation such as methanol oxidation. However, the poor methanol oxidation ability by polymer dots still inhibits the overall photocatalytic reaction occurring in the neutral condition. In this work, an organic molecular catalyst 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl radical is covalently linked to a fluorene unit in a polymer skeleton, eventually enabling photocatalytic hydrogen peroxide production coupled with methanol oxidation in the neutral condition. By conducting various spectroscopic measurements, charge transfer between components in this molecular catalyst-immobilized polymer dots system is studied and found to be very efficient for hydrogen peroxide production coupled with alcohol oxidation. This work proves a strategy for designing polymer dots photocatalysts with molecular catalysts, facilitating their future development and potential applications in other fields such as water splitting, CO2 reduction, photoredox catalysis and photodynamic therapy.

In this communication, we have measured the densities and ultrasonic velocities for the binary mixtures of (Ortho Methoxy Aniline + Benzene) and (N-Methyl Aniline + Benzene) over the entire volume fraction range 0.1-1 at303K- 318K and at ambient pressure. The experimentally obtained data were used to evaluate different derived parameters such as adiabatic compressibility, Intermolecular free length, acoustic impedance, molar volume, molar sound velocity, molar compressibility, relative association, excess volume, and excess adiabatic compressibility. The outcome of all derived parameters is well explained by intermolecular interaction studies present in the non-aqueous binary organic liquid mixture. Moreover, the densities and ultrasonic velocities of the binary mixtures were used to compare different correlating relations. The negative values of the excess volume and excess adiabatic compressibility with volume fraction and temperature confirm the presence of strong interaction through dipole-dipole and dipole-induced dipole interactions in the studied systems., Full text license: CC BY 4.0

The development of liquid electrolytes receives significant attention within the field of battery research. New concepts are emerging, and one of these groundbreaking ideas is localized high concentration electrolytes (LHCEs). The fundamental characteristic of this type of electrolyte is related to its solvation structure. However, despite the progress made, the solvation process and its relationship towards physicochemical and electrochemical properties are not yet fully understood. A comprehensive understanding of LHCEs and their solvation structure requires further dedicated research and analysis. This concept review offers a thorough examination of the design principles governing LHCEs, elucidates methodologies for investigating solvation structures, connects these insights to interphase chemistry, and explores potential applications in future battery technology.

Green surfactants, categorized as biobased and biosurfactants, pose formulation challenges due to their compositional variability and biodegradability. Our work addresses these challenges in formulating a hard surface cleaning spray. We utilize glucamide surfactants with a high renewable carbon index (RCI=95 %), incorporating limonene as both solvent and perfume. Additionally, the concept of formulating a concentrated "juice" is explored. A partial phase diagram guides our formulations, and rheology and small angle X-ray scattering (SAXS) pinpoint the optimal dilution line. Our concentrated formula exhibits liquid crystalline phases, offering potential applications in gel-like tablets. Performance evaluations against a market product reveal mixed results, indicating the need for further optimization. The study emphasizes a formulation minimalism approach, aligning with modern trends. It showcases the potential of green surfactants, providing insights into their behavior under varying concentrations and paving the way for environmentally friendly cleaning solutions.

Molecules involved in solvation shells have properties differing from those of the bulk solvent, which can in turn affect reactivity. Among key properties of these molecules are their nature and electronic structure. Widely used tools to characterize this type of property are X-ray-based spectroscopies, which, however, usually lack the capability to selectively probe the solvation-shell molecules. A class of X-ray triggered "non-local" processes has the recognized potential to provide this selectivity. Intermolecular Coulombic decay (ICD) and related processes involve neighbouring molecules in the decay of the X-ray-excited target, and are thus naturally sensitive to its immediate environment. Applying electron spectroscopy to aqueous solutions, we explore the resonant flavours of ICD and demonstrate how it can inform on the first solvation shell of excited solvated cations. One particular ICD process turns out to be a potent marker of the formation of ion pairs. Another gives a direct access to the electron binding energies of the water molecules in the first solvation shell, a quantity previously elusive to direct measurements. The resonant nature of the processes makes them readily measurable, providing powerful new spectroscopic tools. X-ray triggered non-local processes, such as Intermolecular Coulombic Decay, are shown here to selectively probe solvation-shell molecules in solution and provide new information on their electronic structure and on ion-pair formation.

Solar fuels offer a promising approach to provide sustainable fuels by harnessing sunlight1,2. Following a decade of advancement, Cu2O photocathodes are capable of delivering a performance comparable to that of photoelectrodes with established photovoltaic materials3,4,5. However, considerable bulk charge carrier recombination that is poorly understood still limits further advances in performance6. Here we demonstrate performance of Cu2O photocathodes beyond the state-of-the-art by exploiting a new conceptual understanding of carrier recombination and transport in single-crystal Cu2O thin films. Using ambient liquid-phase epitaxy, we present a new method to grow single-crystal Cu2O samples with three crystal orientations. Broadband femtosecond transient reflection spectroscopy measurements were used to quantify anisotropic optoelectronic properties, through which the carrier mobility along the [111] direction was found to be an order of magnitude higher than those along other orientations. Driven by these findings, we developed a polycrystalline Cu2O photocathode with an extraordinarily pure (111) orientation and (111) terminating facets using a simple and low-cost method, which delivers 7 mA cm−2 current density (more than 70% improvement compared to that of state-of-the-art electrodeposited devices) at 0.5 V versus a reversible hydrogen electrode under air mass 1.5 G illumination, and stable operation over at least 120 h., Correction in: Nature, vol. 629, article-ID E14DOI: 10.1038/s41586-024-07489-8

Site-specific atom probe tomography coupled with electron back scattering diffraction studies were used for the first time to elucidate the multi-element solute segregation and clustering at austenite-ferrite interface during early stages of phase transformation in Fe-Mn-Si-C steel alloyed with Ti, Mo and Nb. The results have shown the existence of negligible partitioning local equilibrium at interfaces with segregation of C, Mn, Ti and Mo to interfaces having the angle deviation in the range from 2.9 to 12° from Kurdjumov-Sacks orientation relationships (K-S ORs), but either irregular incident planes or the ones not following the matching according to K-S ORs. The segregation of Nb was less common, which was linked to the earlier occupancy of interfaces by Ti and Mo. Variation in solute segregation along the same interfaces is highlighted. Presence of clusters within and in close proximity to the interface is detected. The links between interface orientation, solute segregation, clustering and interphase precipitation are discussed., Full text license: CC BY-NC 4.0