This study focuses on the effects of dispersing tin thiohypodiphosphate ferroelectric nanoparticles (Sn2P2S6) on the structural, ferroelectric, and dielectric properties of a ferroelectric liquid crystal (SmC*) phase. Our findings show that nanoparticle dispersion leads to modifications in phase transition temperatures, spontaneous polarization, and dielectric relaxation modes associated with ferroelectricity. These effects are attributed to changes in the viscoelastic parameters of the SmC* phase. Two concentration regimes were identified: at low concentrations, nanoparticles are well-dispersed, introducing local defects in the smectic layers and distortions in the helical structure, thereby enhancing the viscoelastic properties of the FLC. At higher concentrations, aggregation of nanoparticles reduces the dispersion effects, and the nanocomposite behavior tends to resemble that of the pure liquid crystal.

The rational design of efficient visible-light-driven photocatalysts remains a challenge for sustainable hydrogen production. Herein, we present a combined computational and experimental study on NdFeO3/g-C3N4 heterojunctions, determined through a systematic screening of perovskite/2D-material combinations. From a pool of eleven theoretically promising heterojunctions, NdFeO3/g-C3N4 type-II heterojunction was selected for in-depth analysis due to its favorable band alignment and anticipated charge separation properties. Both pristine and Au-decorated NdFeO3/g-C3N4 composites were synthesized and thoroughly characterized using various analytical tools. Our results reveal that the heterojunction exhibits an internal electric field at the interface, which suppresses charge carrier recombination. The incorporation of Au nanoparticles introduces ohmic contacts that drastically reduce the interfacial electron transfer resistance, thereby enhancing charge extraction efficiency. Photoelectrocatalytic measurements under standard AM1.5G solar illumination reveal a remarkable enhancement in hydrogen evolution activity, an 18-fold increase of hydrogen production is recorded for the Au(NFO0.9/g-CN0.1) composite relative to bare NdFeO3. These findings underscore the potential of integrating high-throughput computational screening with targeted synthesis to accelerate the rational design of next-generation type-II photocatalysts for solar-driven hydrogen generation.

In this study, we present an investigation into the synthesis of ZnO nanopillars via electrodeposition techniques with a particular emphasis on the precise control of their nanometric diameters and their crystallographic orientation. The electrodeposition process was carried out on various substrates, including glass coated with transparent conducting oxides and platinum-coated silicon wafers. We analyze the influence of substrate properties (surface roughness and electrical conductivity) on the growth behavior of ZnO nanopillars, focusing on their crystallographic orientation, morphology, and coverage ratio. The role of surfactants in directing the electrodeposition process is also explored in depth. Among the surfactants tested, hexamethylenetetramine (HMTA) emerged as the most effective for promoting vertically aligned nanopillar growth. Furthermore, the influence of two different zinc precursors (acetate and zinc nitrate) has been studied. Our findings demonstrate that zinc nitrate improves the crystallographic texture and enhances photocurrent generation. The photoelectrochemical performance of the synthesized ZnO nanopillars is evaluated through measurements of the charge carrier transfer and recombination rates as a function of the applied potential. Remarkably, the nanopillars exhibit a charge transfer efficiency exceeding 80%, highlighting their strong potential for integration into photoactive devices, such as solar cells. This study underscores the critical role of substrate selection, surfactant chemistry, and precursor choice in tailoring ZnO nanopillar growth and optimizing their optoelectronic properties for energy conversion applications.

The La2Ti2O7 photocatalyst, synthesized using a glycine-assisted sol-gel method, demonstrates excellent efficiency in the photodegradation of both anionic dyes, such as Naphthol Green B and Eosin Y, and cationic dyes like Crystal Violet, at a pH of 5.8 under UV irradiation. Kinetic studies reveal that the degradation process follows first-order kinetics, specifically described by the Langmuir-Hinshelwood model. Additionally, this photocatalyst has been successfully utilized for the photoreduction of Cr(VI) to Cr(III). Mott-Schottky analysis of La2Ti2O7 confirms its n-type semiconductor behavior and provides insights into its flat band potential. The conduction and valence band levels were determined experimentally through flat band potential measurements and optical band gap analysis, showing good agreement with theoretical values obtained from the Mulliken electronegativity approach. Furthermore, photocurrent transient response measurements under both UV and solar excitation reveal a higher photocurrent density in the UV spectral region, consistent with the material's absorption characteristics. This suggests the photocatalyst's potential applicability in treating various pollutants, making it a promising candidate for wastewater remediation. For the first time, to the best of our knowledge, the impact of La2Ti2O7 toxicity on the human body was also investigated. Specifically, its effects were studied on the human intestinal barrier and a human in vitro blood-brain barrier model. The results indicate no cytotoxicity at concentrations ranging from 0.1 to 1 mu g.mL-1, highlighting its potential as a safe and effective material for environmental and biomedical applications.

We present a comprehensive study, combining experimental and theoretical approaches, to assess the hydrogen evolution reaction (HER) efficiency of BiFeO3-based solid solutions. Initially, we investigate the electronic and optical properties of these compounds, with a particular focus on band edge alignment relative to water redox potentials. Our findings show that the materials exhibit optimal band gaps of approximately 2.0 eV, indicative of enhanced visible light absorption and favorable energetic alignment to drive efficient hydrogen generation. To corroborate our theoretical predictions, we perform photoelectrochemical measurements on selected BiFeO3 based compounds synthesized via the solid-state method. Our experimental results reveal a high hydrogen yield, with BiFeO3-SrTiO3 achieving a production rate of similar to 114 mu mol/L in 30 min, outperforming BiFeO3-BaTiO3 (similar to 70 mu mol/L) and pristine BiFeO3 (similar to 61 mu mol/L). These findings validate our theoretical assumptions and demonstrate the superior HER performance of BiFeO3-SrTiO3, positioning it as a highly promising candidate for sustainable hydrogen production.

In this work, the electrocatalytic activity of hematite with a porous and compact structure was investigated in the process of oxygen evolution. Porous coatings were synthesized using potentiodynamic ElectroDeposition (ED) and thermal treatment, while compact coatings were synthesized by Magnetron Sputtering (MS). Electrocatalytic evaluation of the coatings showed that there is no significant difference with respect to the overpotential of the reaction onset potential, which is 342-353 mV for electrodeposited samples and 341-355 mV for those obtained by the MS method. However, the advantage of compact coatings has emerged at higher current density values, when the activity of porous coatings faces limitations due to diffusion from and into the pores. Calculations of the coefficient b of the Tafel equation revealed the superiority of porous structures (avg. 48 mV center dot dec-1) at the beginning of the reaction over compact coatings (avg. 56 mV center dot dec-1).

The LaAl1-xFexO3 oxides (with x = 0, 0.05, 0.10 and 0.15) have successfully synthetized by the citrate-based Sol–Gel route. X-ray diffraction analysis confirms the preservation of the rhombohedral structure (as pristine-LaAlO3) with a linear increase of the lattice parameters according to the x value. The broadening of diffraction lines was indicated the nanometric nature of the synthetized oxides and the crystallites size was determined using the Scherrer equation. Additionally, the Diffuse Reflectance Spectroscopy revealed a modification of absorption properties for the iron-based compounds, suggesting their potential as effective photocatalysts under visible light. The photogenerated current was also exhibited an enhanced efficiency in the separation of electron–hole pairs for higher Fe3+ ions substitution rates. The variation in current density follows a power-law relationship with light power density and a wavelength-dependent study demonstrated that compounds containing iron show significantly more effective absorption in the blue spectral region. Based on these findings, the photocatalytic properties were further investigated. For the unsubstituted LaAlO3 (LA Sample), low photocatalytic activity, achieving only 10

Mixed anion compounds have attracted growing interest in solid-state chemistry as a way to tailor physical properties. In this work, we synthesized new silver niobium and tantalum pyrochlore oxyfluorides by an ion-exchange reaction from Na2M2O5F2 (M = Nb or Ta). Instead of a classical Na+/Ag+ cation exchange, a less conventional dual cation and anion exchange reaction (2 Na+ + F-)/(Ag+ + H2O) takes place. Indeed, chemical and thermal analyses, as well as Rietveld refinement and 19F NMR, reveal the formation of AgTa2O5F·H2O and Na0.4Ag0.8Nb2O5F1.2·0.8H2O leading to a significant band gap narrowing of approximately 0.4 eV, as determined by diffuse reflectance spectroscopy. DFT calculations show that Ag 4d-O 2p states are located at the edge of the valence band and that the presence of fluorine in the coordination sphere of Ag promotes the hybridization and hence contributes to the band gap narrowing.

We report on enhancing the electro-optical response of nematic liquid crystal (6CHBT) by doping with increasing concentration of ZnO nanoparticles. Photosensitive response of this hybrid system is shown through the generation of a photocurrent at 450 nm. The critical role of surfactants to ensure uniform dispersion of nanoparticles in the liquid crystal matrix and their interplay with the charge carrier collection process are also demonstrated. These properties allow these hybrid liquid crystals to be used in the design of photodetectors integrated into liquid crystal displays without compromising its transparency.

We report here the results of an experimental investigation of the electronic properties and photocurrent responses of the CaFeOQ and La2O2Fe2OQ2 phases and a computational study of the electronic structure of polar CaFeOSe. We find that both CaFeOQ (Q = S and Se) have band gaps and conduction band edge positions compatible with light-driven photocatalytic water splitting, although the oxysulfide suffers from degradation due to the oxidation of Fe2+ sites. The higher O/Q ratio in the Fe2+ coordination environment in CaFeOSe increases its stability without increasing the band gap beyond the visible range. The photocurrent CaFeOSe shows fast electron-hole separation, consistent with calculated carrier effective masses. These results suggest that these iron oxychalcogenides warrant further study to optimize their stability and morphology for photocatalytic and other photoactive applications.

The crystal structure, electronic properties, photocatalytic activity, and photocurrent response of a new antimony oxysulfide Sr2Sb2O2S3 and its oxyselenide analogue Sr2Sb2O2Se3 are presented. Both oxychalcogenides contain heteroleptic SbOQ(4) units with stereochemically active 5s(2) electron pairs. Our combined experimental and computational study highlights the structure-property relationships in this family of materials. By means of density functional theory calculations, we show very low effective masses for the electrons (m(e)* = 0.191(6) and 0.163(2) m(0)) and holes (m(h)* = 0.276(2) and 0.190(2) m(0)) for the oxysulfide and the oxyselenide, respectively, an indication of very high mobilities. Using DFT calculations, we attribute the low effective mass values (related to the curvature of the bands) to the nature and strength of the bonding between the lone pair electrons and the anions in the studied structure compared with other structure (Sr6Cd2Sb6S10O7). We analyze the states contributing to the lone pair stereoactivity and consequently to the observed photocurrent response and photocatalytic behavior under solar irradiation. This activity, the band gap values, and the band edge positions illustrate the potential of these antimony oxychalcogenides as promising candidates for water splitting using solar energy. Our study unlocks some key features in designing oxychalcogenides with low effective masses, which are advantageous for photocatalysis.

The new thioapatite Ba5(VO4-αSα)3X (X = F, Cl, I) series of compounds was prepared and characterized. Compared to known apatite phases built from unconnected vanadate VO4 groups separated by Ba2+ cations delimiting halide-filled channels, their crystal structure is built from mixed anion thiovanadate VO4-αSα, where V5+ is surrounded by both O and S, therefore exhibiting a triple anion lattice. Here, the strategy consisting in incorporating a chalcogenide anion aims at raising the valence band to bring the band gap to the visible range in order to reach photoactive materials under visible light. Both the halide anion nature and the S/O ratio impact the materials' photoconductivity. While the photocurrent response is comparable to that found in the recently investigated apatite phase Pb5(VO4)3I, a short carrier lifetime is detected as well as a shift of the activity toward the visible light. This apatite series combining thiovanadate and halide-filled channels opens new perspectives in the extended field of apatites and their applications.

Polymorphic phases of copper pyrovanadate (α- and β-Cu2V2O7) were synthesized by solid state reaction and the mechanisms governing the phase transitions have been highlighted by the ThermoGravimetric Analysis (TGA) and the Differential Scanning Calorimetry (DSC). The thermal evolution of the lattice parameters was determined by high temperature X-ray Diffraction revealing negative thermal expansion coefficients. The thermogravimetric analysis coupled with differential scanning calorimetry was also used to determine the optimal conditions to obtain a dense target in order to produce thin films by the Pulsed Laser Deposition (PLD) technique. Thin films elaborated under different oxygen pressures and temperatures exhibit a β-Cu2V2O7 polycrystalline phase and their band gap indicates absorption in the visible range. These oxides can be used as photoanodes and their photoelectrochemical properties were studied for both bulk (α-Cu2V2O7) and thin films (β-Cu2V2O7), as a function of the wavelength and/or intensity of the luminous flux. The best photocurrent efficiency was obtained under 450 nm illumination. Moreover, in the case of thin films, we have observed a linear evolution of the current density with the luminous flux. Finally, the photostability of thin films was measured and shows a reduction in the photocurrent of 8% after 1 h of measurement. This photocorrosion phenomenon was also highlighted by the elemental mapping performed on thin films by Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectrometry (EDS).