In this study, a novel dual-molecule system made of spiropyran-loaded magnetite is designed and synthesized in the laboratory for the degradation of Bisphenol A. Comprehensive chemical, morphological, structural, photo-responsive, and cytotoxic examinations show that the smart material has been successfully functionalized and acts as a highly active catalyst. Spiropyran-loaded magnetite nanoparticles demonstrate efficient singlet oxygen generation (approx. 59 µM of ¹O₂ in only 60 min) while maintaining sustainable operational parameters, offering a promising alternative to conventional advanced oxidation process-based systems. At a catalyst loading of 1 g/L, all photodegradation reactions followed pseudo-first-order kinetics, with apparent rate constants (k) in the range of 0.0078–0.1549 ± 0.0007 min⁻¹ (R2 > 0.989). Moreover, the photocatalyst was successfully used in four consecutive runs, without significant loss of catalytic activity. In agreement with photocatalytic oxidation data, the cytotoxicity results showed that during the photocatalytic reaction, the samples were less cytotoxic. Based on the obtained results, among the organic molecules used as photosensitizers, spiropyrans hold great promise for the development of smart photocatalysts.

In this work, chitosan-based cryogels, either native (CS) or functionalized with thiourea (CSTU), were first evaluated as sorbents for Cu(II) ions, and then transformed into heterogeneous catalysts for hydrogenation of 4-nitrophenol (4NP). In batch experiments, the maximum Cu(II) uptake by the CS and CSTU cryogels reached 1.56 mmol Cu(II)/g and 1.74 mmol Cu(II)/g, respectively. XPS and EPR investigations showed that amino and hydroxyl groups on the CS backbone are the main contributors to Cu(II) sorption. The sorbed Cu(II) ions were subsequently reduced with NaBH4 to generate copper nanoparticles (CuNPs) uniformly dispersed in the pore walls of the cryogels. The prepared CS/CuNPs and CSTU/CuNPs composites were characterized using FTIR, SEM, EDX, TEM, TGA, and uniaxial compression measurements. The kinetics of the 4NP hydrogenation reaction were influenced by the chemical structure of the cryogels and by the NaBH4 concentration. The apparent rate constants (kapp) increased proportionally with the concentration of NaBH4, up to 1.24 ± 0.053 min-1 and 1.01 ± 0.064 min-1 for the CS/CuNPs and CSTU/CuNPs composites, respectively. The catalytic activity was maintained over four consecutive cycles, while XPS analyses demonstrated that the chemical structure of the composite catalysts was preserved after use. Furthermore, the composites achieved 4NP conversion efficiencies above 91% in both tap and lake waters, demonstrating their adaptability across diverse aqueous environments. This study presents a straightforward strategy to convert Cu(II)-loaded cryogels into reusable, high-performance catalysts, thereby contributing to sustainable wastewater remediation practices.

This study reports the synthesis, structural characterization, and chemical analysis of pure NaMgF3 and CeO2-doped NaMgF3 perovskite materials. The compounds were prepared via a combined co-precipitation and solid-state reaction approach, ensuring homogeneous incorporation of cerium into the NaMgF3 lattice. X-ray diffraction XRD analysis confirmed that all samples crystallize in a single-phase orthorhombic perovskite structure (space group Pbnm) while XPS provides insights into the bonding, chemical environment, and chemical state of elements present respectively. According to XRD studies Ce incorporation inducing minor peak shifts, a slight reduction in crystallite size (from 35.7 nm to 34.7 nm), and decreased lattice strain (0.27

Piezo-enhanced photocatalysis is progressively considered an eco-friendly technology for contaminant removal, harvesting not only solar energy but also mechanical vibrations found in nature. Multiferroic materials present a coupled effect of various properties and can potentially increase the applicability of this process. In this study, Cr- doped bismuth ferrite thin film was deposited on SrTiO3 substrate by HiPIMS, and its photo-, piezo-, and piezo-photocatalytic efficiencies in Rhodamine B (RhB) degradation were analyzed. The highest removal percentage was found under the simultaneous exposure of visible light and mechanical vibrations, reaching 86.2% after 180 min. The calculated efficiencies for photo- and piezocatalysis were 12.2% and 83.7%, respectively. The rate constant (k) for piezo-photocatalysis was 16.1 times higher than that found during photocatalytic experiments. To assess the contribution of each reactive species to the decomposition process, different reagents were added to the Rhodamine B contaminated solution. The results revealed that when p-benzoquinone was used, the degradation efficiency declined significantly from 86.2% to 37.6%, suggesting that superoxide radicals (O2 center dot-) play a key role in decomposing RhB molecules. The structural, chemical, optical, and ferroelectric changes caused by the catalytic processes were analyzed and linked to the proposed degradation mechanisms. The poor photocatalytic efficiency was linked to an improper band structure and an improper polarization orientation of the ferroelectric domains in the as-deposited film. The degradation mechanisms in piezo-photocatalysis were driven partly by the band bending caused by mechanical vibrations and partly by the reorientation of the induced polarization of the domains in the unstrained film.

NaMgF3 nanoparticles were successfully synthesized via a co-precipitation method and calcined at 500-700 degrees C for different durations to investigate the influence of thermal treatment on their structural and compositional properties. XRD confirmed a stable single-phase orthorhombic NaMgF3 structure under all conditions. Increasing the calcination temperature resulted in crystallite coarsening from 34.1 to 39.8 nm, while prolonged treatment at 700 degrees C (12 h) further enhanced grain growth up to 46.7 nm, accompanied by a significant reduction in microstrain (from 0.33% to 0.25%) and dislocation density (from 0.73 to 0.52 x 10-3 nm-2), indicating defect annealing and lattice relaxation. XPS revealed temperature-dependent shifts in Na 1s, Mg 1s and F 1s binding energies, suggesting stabilization of cation coordination environments and reduction in surface defects. EDS and XPS confirmed stoichiometric composition with good agreement to the theoretical NaMgF3 ratio. These findings demonstrate that calcination plays a critical role in tuning the structural integrity, defect distribution, and chemical stability of NaMgF3 nanoparticles, which is essential for their integration in radiation detection, dielectric, and optoelectronic applications.

Given the increasing environmental degradation, this study investigates advanced zinc oxide (ZnO)-based materials for the mineralization of toxic compounds through the combined action of photo- and piezocatalysis. Two complementary strategies were employed to enhance catalytic efficiency. First, ZnO1-xNx thin films were deposited by reactive high-power impulse magnetron sputtering (R-HiPIMS) to reduce the band gap energy. Second, flower-like ZnO nanostructures were synthesized using the pulsed thermionic vacuum arc (p-TVA) technique to increase the specific surface area. Both systems were further modified by decoration with Ag2O nanoparticles to improve charge separation. The R-HiPIMS technique offers significant advantages in terms of precise control over processing parameters, enabling accurate tuning of film properties, including microstructure, chemical composition, and electronic structure. However, films produced via R-HiPIMS generally exhibit lower photo-piezocatalytic activity compared to nanostructured counterparts, primarily due to their comparatively reduced effective surface area and limited charge separation efficiency. In contrast, the p-TVA technique enables the synthesis of nanostructured thin films with substantially enhanced photo-piezocatalytic performance. This improvement is attributed to the increased effective surface area and the promotion of more efficient electron-hole pair separation. The materials were comprehensively characterized in terms of optical properties (UV-Vis spectroscopy), chemical composition and bonding (XPS), crystalline structure (XRD), surface morphology (FE-SEM), and photo-piezocatalytic performance. Catalytic activity was evaluated via the degradation of methylene blue (MB) under visible light irradiation and mechanical vibrations. Nitrogen incorporation in ZnO1-xNx thin films led to an increase in photocatalytic efficiency from 20% to 28.7%, while the simultaneous application of light and mechanical stimulation increased efficiency to approximately 50%. Under identical irradiation conditions, Ag2O-decorated ZnO and Ag2O-decorated ZnO1-xNx exhibited photo-degradation reaction rate constants up to 65% higher than bare counterparts, attributed to reduced electron-hole recombination. ZnO nanostructures achieved degradation efficiencies of 59%, rising to 88.3% with Ag2O decoration under solar illumination for 120 min. When combined with mechanical vibrations, after 60 min, the degradation efficiencies reached 93% for ZnO and 98% for Ag2O/ZnO systems. A photodegradation mechanism of Ag2O NPs-decorated ZnO heterostructures was proposed.

In this paper, we have investigated the photocatalytic performances of some yttrium-doped ZrO2 films for decomposing Rhodamine B and Methylene Blue. The as-deposited thin films (obtained by RF magnetron sputtering) were heat-treated to stabilize their structure. To assess the films' characteristics, a group of analytical methods (XRD, XPS, AFM and DRS) allowed for the determination of their structural, surface, and optical properties. These characteristics were correlated with the observed photocatalytic activity and wetting behaviour. The Y-doped ZrO2 film with medium nanoparticle size and a high contribution of the oxygen vacancy is found to be more efficient in Rhodamine B and Methylene Blue photodegradation; the 100% degradation efficiency was reached in 70 min and 40 min, respectively, for the 3 mg/L solution dye. The photodegradation mechanism is driven by photogenerated holes, and a possible reaction mechanism was proposed. By investigating the charge carrier separation at the film-ITO interfaces, made through a comparative analysis of their determined band edge potentials, we conclude that the transfer is not possible in either of the semiconductor pairs, so ITO does not "help" the photocatalytic process.

Ca1-xBixFeO3-s ceramics were synthesized via a solid-state reaction followed by a two-step heat treatment to investigate the influence of Bi substitution on their structural, dielectric, electrical, and gas sensing properties. Xray diffraction revealed a composition-driven phase evolution, from a single orthorhombic Pcmn phase in undoped and lightly doped samples (x <= 0.1) to a fully stabilized Pbnm phase at 50% Bi. Complementary XPS and Raman analyses confirmed the incorporation of Ca, Bi, Fe, and O without detectable impurities. Impedance spectroscopy indicated a relaxor-like dielectric behavior with a diffuse phase transition shifting to lower temperatures upon Bi doping. The dielectric constant reached a maximum value of 7.5 & times; 104 at 260 degrees C for x = 0.1, associated with defect dipole relaxation. Microstructural analysis showed a progressive densification with increasing Bi content, with relative density rising from 50.3% (x = 0.1) to 71.2% (x = 0.5), consistent with reduced porosity observed in SEM images. Notably, the Ca0.5Bi0.5FeO3-s composition, combining high density with lower conductivity at room temperature, exhibited the strongest ethanol sensing response, attributed to more efficient resistance modulation during gas adsorption. These results position Ca1-xBixFeO3-s as a promising multifunctional platform for next-generation electronic devices, combining high-temperature dielectric components (ceramic capacitors in harsh-environment electronics) and low-power room-temperature chemiresistive ethanol sensors.

The photocatalytic performances in decomposing Rhodamine B (RhB) and Methylene Blue (MB), were analyzed by using different nitrogen-doped-ZrO2 films. The films were deposited on ITO/glass by high-power impulse magnetron sputtering, at 900Hz and 1250 Hz repetition frequencies, and then subjected to a heat treatment. A correlation of the structural, morphological, optical and electronic properties of the low-N-doped-ZrO2 thin film (900 Hz) with the hydrophilic and photocatalytic performance, in decomposing both dyes, was performed. Both N-doped films are absorbent in visible range, with the optical bandgap of 2.61 eV and 2.54 eV, much lower than 4.42 eV for the undoped one. The average roughness suffered an important decrease by N doping (900Hz), from 8.3 nm to 0.6 nm. The doped films show comparable hydrophilic properties, remaining activated for about 8 days, but the film under study (900 Hz) didn't become superhydrophilic. The doped film (900Hz) had a slightly higher degradation efficiency than the higher-doped-one (1250Hz-previously studied only for RhB decomposition) for the same dye and solution concentration, which decreased from 99 % for 1 mg/L dye to 70 % and 91 % for 5 mg/L RhB and MB, respectively. The pseudo-first order rate constant of RhB degradation decreased from 2.549.10-2 min-1 (1 mg/L) to 0.852.10-2 min-1 (5 mg/L), while for MB was approximate to 7.4 times higher. By calculating the ECB and EVB values for the investigated film, we discussed on the species involved in the degradation process and on the role of the substrate on the electrons-holes separation, important in decreasing their recombination. ITO substrate didn't favor a separation of electrons from holes in the low-N-doped films compared to its counterpart. The photocatalysis was favored by the water oxidation process. The decrease in the low-N-doped-ZrO2-film stability was mainly dictated by the lower nitride concentration with 4.75 %.

Porous nanocrystalline lanthanum perovskite La-Fe-O (LaFeO3) powders were synthesized by the sol-gel self-combustion method, using polyvinyl alcohol as the colloidal medium. The perovskite structure of the material, without secondary phases, was obtained at a calcination temperature of 900 °C for 40 min. The obtained powder was tested for catalytic activity at moderate temperatures (50-550 °C) for ethanol, methanol, acetone, benzene, and Pb-free gasoline vapors. Catalytic combustion begins at quite low temperatures (60-200 °C), compared to normal combustion, and this can be attributed to the nanometric crystallites, the large specific surface area, and the presence of iron cations with different valences, Fe3+/Fe2+, resulting from the method we used to obtain the material. The degree of conversion reaches values of over 99% for acetone and ethanol vapors at a temperature of 270 °C and 310 °C, respectively, and over 97% for methanol vapors at a temperature of 330 °C. The degree of conversion for Pb-free gasoline and benzene reaches somewhat lower values, over 88% at much higher temperatures, 470 °C and 550 °C, respectively. The lanthanum perovskite catalyst, LaFeO3, obtained by the presented preparation method, can be recommended for the combustion of acetone, ethanol, and methanol vapors. The performance of this catalyst is remarkable and can be compared to that of a catalyst containing noble metals in its composition.

Natural resources have multiple advantages, including being eco-friendly, inexpensive, non-toxic, and widely available, as well as having good activity in pollutant removal. This study explores the performance of Romanian volcanic tuff tested on two persistent dyes, Reactive Black 5 (RB5) and Methylene Blue (MB), via photo-Fenton-like oxidation. Different approaches, including Scanning electron microscopy (SEM), X-ray diffraction (XRD), surface-enhanced Raman scattering (SERS), Fourier transformed infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and N2 adsorption-desorption measurements, were used to investigate the structural, mineralogical, and textural properties of natural and modified volcanic tuff. The clinoptilolite phase in volcanic tuff is up to 85%. Furthermore, the structural investigation of volcanic tuff using SERS provides an original feature of this study. In real wastewater effluents, modified volcanic tuff proved to be highly effective at removing RB5 and MB by more than 90%, k = 0.0242-0.0309 min- 1. After five cycles, RB5 decolorization is still greater than 60%. The obtained findings demonstrate that Romanian volcanic tuff can be successfully exploited as a green resource in wastewater treatment.

Carbon nanodots have recently attracted attention as fluorescence imaging probes and magnetic resonance imaging (MRI) contrast agents in diagnostic and therapeutic applications due to their unique optical properties. In this work we report the synthesis of biocompatible Mn (II)-doped carbon nanodots and their performance as fluorescence and MRI contrast agents in in vitro assays. The thermal decomposition of a Diphenylhydantoin-Mn(II) complex assured the incorporation of manganese (II) ions in the carbon dots. The obtained materials display a favorable spin density for MRI applications. The synthesized Mn(II)-CNDs also displayed remarkable photoluminescence, with a bright blue emission and good response in in vitro fluorescence imaging. Cytotoxicity investigations revealed good cell viability on malignant melanoma cell lines in a large concentration range. A cytotoxic effect was observed for MG-63 osteosarcoma and breast adenocarcinoma cell lines. The in vitro MRI assays demonstrated the potentialities of the Mn(II)-CNDs as T2 contrast agents at low dosages, with relaxivity values higher than those of commercial ones. Due to the simplicity of their synthetic pathway and their low cytotoxicity, the prepared Mn(II)-CNDs are potential alternatives to currently used contrast agents based on gadolinium complexes.

We report a water soluble MgO/Ch/ZnPc(COOH) 4 self-assembled room-temperature phosphorescent material with unique performance, such as a long lifetime of 5.01 μs, large Stokes shift of 105 nm and a phosphorescence quantum yield of 10.63%.

This study examined the effects of prolonged exposure to dielectric barrier discharge plasma at atmospheric pressure and saline stress on quinoa seeds (Chenopodium quinoa cv. Titicaca). Reactive species (O3, N2O, and CO2) were monitored in real time, and changes in the surface chemistry, mesoscale morphology, germination rate, and fresh biomass were analyzed. During extended plasma treatment, it is probable that an equilibrium will be established between the concentration of reactive species in the plasma and the functional groups present on the seed surface. The plasma treatment changed the seed surface and increased the oxygen-to-carbon ratio without causing structural damage. The germination assay showed that 20 min exposure of seeds to plasma did not negatively affect the process. Plasma had a slight impact on fresh biomass, whereas 300 mM NaCl stress significantly reduced the biomass. Plasma can be both a treatment and a stressor, and excessive oxidative stress from prolonged plasma exposure can reduce germination and biomass.

Amorphous ZrO2 thin films with increasing Mg content were deposited on quartz substrates, by dip coating method. The films are transparent in the visible domain and absorbent in UV, with an optical band gap that decreases with the increase of Mg content, from 5.42 eV to 4.12 eV. The temperature dependent conductivity measurements showed typical semiconductor comportment. The decrease of the electrical conductivity by Mg doping was related to the increase of the OH groups (37% to 63%) as seen from X-ray Photoelectron Spectroscopy. It was found out that the electrical conductivity obeys the Meyer-Neldel rule. This rule, previously reported for different disordered material systems is obtained for ZrO2 for the first time in the literature. Exploring novel aspects of Mg-doped ZrO2, the present study underscores the origin of the Meyer-Neldel rule explained by the small-polaron hopping model in the non-adiabatic hopping regime. Determination of the presence of such a conduction mechanism in the samples hold promise for comprehending the important aspects, which might be a concern in developing various devices based on Mg-doped ZrO2.

Cobalt(II) chloride (CoCl2) being in the vicinity of polyimide chains entails modifications in terms of the molecular dynamics, which are mainly governed by the possible presence of amic acid residual groups, by the transition-metal-type characteristics of cobalt and by the CoCl2 content. Polyimide was synthesized using poly(amic acid) according to the reaction of 2,2′-bis(3,4-dicarboxylphenyl)hexafluoropropane dianhydride (6FDA) with 3,3′-dimethyl-4,4′-diaminodiphenylmethane (MMDA) in N,N-dimethylacetamide. CoCl2 was added before the thermal imidization of the poly(amic acid). An experimental approach was designed to establish the interaction between the polyimide and CoCl2 and whether the interaction depends on the quantity of the salt. Evidence for the existence of residual amic acid groups was obtained using second derivative Fourier Transform Infrared Spectroscopy (FTIR) and with the help of 2D correlation spectroscopy (2D-COS). Moreover, FTIR, along with X-ray photoelectron spectroscopy (XPS), revealed the interaction between the polymer and CoCl2, primarily in the form of Co(II)-N coordinated bonds. Nevertheless, the coordination of cobalt with suitable atoms from the amic acid groups is not precluded. The results of dynamic mechanical analysis (DMA) featured a specific relaxation assigned to the presence of CoCl2 in the polymeric film and demonstrated that its (non)reinforcing effect depends on its content in the polyimide.

In the present study, two iron phthalocyanine (FePc)-based nanocatalysts were synthesized and fully characterized. The carbon nanotubes (CNT) functionalized in an easy way with either Fe(II)Pc or Fe(III)Pc exhibit a very good catalytical activity. The activity in real wastewater effluent was comparable with the activity in distilled water. The procedure of modeling and optimizing with the assistance of chemometrics, utilizing design of experiments (DOE) and response surface methodology (RSM), revealed the conditions of optimum for decaying Reactive Yellow 84 on the nanocatalysts FePc_CNT. These optimal conditions included a catalyst dose of 1.70 g/L and an initial concentration (C0) of 20.0 mg/L. Under the indicated optimal conditions, the experimental findings verified that the removal efficiency was equal to Y = 98.92

The influence of the technological conditions on the structure of ZnSe thin films deposited by the close-spaced sublimation method onto SnO2/glass and ITO/glass substrates was studied. The manufacturing parameters were optimized by varying substrate temperature. The X-ray diffraction analysis of the ZnSe thin films showed that films deposited at both types of substrates were polycrystalline in nature with zinc-blende structure, and a preferential peak corresponded to (400) plane for SnO2/glass regarding the substrate temperature, while for ITO/glass substrate with increasing substrate temperature, it was changing from (111) to (220). The elemental composition of ZnSe thin films deposited onto SnO2/glass and ITO/glass substrates was confirmed by the energy-dispersive and X-ray photoelectron spectroscopy techniques. Also, ZnSe/Sb2Se3 heterostructures have been fabricated with SnO2/glass and ITO/glass substrates and investigated for their use in photovoltaic applications. This paper also examined how varying the type of transparent electrode used in solar cell fabrication impacts the device's photovoltaic parameters.

The present study explores an environmentally friendly green approach to obtain cerium oxide nanoparticles via a biomediated route using Mellisa officinalis and Hypericum perforatum plant extracts as reducing agents. The as-prepared nanoparticles were studied for their structural and morphological characteristics using XRD diffractometry, scanning electron microscopy, Raman, fluorescence and electronic absorption spectra, and X-ray photoelectron spectroscopy (XPS). The XRD pattern has shown the centered fluorite crystal structure of cerium oxide nanoparticles with average crystallite size below 10 nm. These observations were in agreement with the STEM data. The cubic fluorite structure of the cerium oxide nanoparticles was confirmed by the vibrational mode around 462 cm−1 due to the Ce-08 unit. The optical band gap was estimated from UV-Vis reflectance spectra, which was found to decrease from 3.24 eV to 2.98 eV. A higher specific area was determined for the sample using M. officinalis aqueous extract. The EDX data indicated that only cerium and oxygen are present in the green synthesized nanoparticles.

The present study investigates the effectiveness of Mg/Al layered double hydroxide (MATclay) for adsorbing Congo Red dye (CR) from wastewater. MATclay was prepared using a cost-effective co-precipitation method at pH 9.5, ensuring both chemical and mechanical stability. The in-depth physico-chemical characterization of MATclay sample was performed using various techniques, including FE-SEM, FT-IR, XRD, DLS, BET surface area, Zeta potential, TEM, XPS, XAS, and TGA. Batch experiments were performed to evaluate the adsorptive performance under different conditions (30-100 mg/L initial concentration, 298-320 K temperature range, and 5-180 min contact time). The adsorption data fit best with the Langmuir model, indicating monolayer adsorption with a maximum capacity of 60.61 mg/g. Post-adsorption analysis with SEM, XRD, and TGA confirmed the interaction of CR with MATclay. . Furthermore, the MATclay material was applied as potential adsorbent for other type of pollutants, namely cationic dye (Methylene Blue) and antibiotics (Metronidazole, Tetracycline, and Cefotaxime), the data obtained in this complementary study showing good results for the removal of Tetracycline and Cefotaxime antibiotics. Overall, MATclay demonstrates potential as an effective adsorbent for CR dye and other pollutants in wastewater treatment.