The microwave-assisted hydrothermal synthesis was developed to synthesize C@Bi2S3 core-shell structures. The poly(ethylene glycol) (PEG) served as a solution viscosity modifier and carbon source in this method. The SEM (Scanning Electron Microscopy) analysis confirmed formation of Bi2S3 nanoflakes with thickness in the range of 50 to 130 nm. TEM (Transmission Electron Microscopy) examination revealed on the flake surface a presence of an amorphous carbon layer with a typical thicknesses ranging from 1 to 10 nm. The thin carbon film did not affect the optical properties of bismuth sulfide, resulting in a direct energy bandgap of 1.33(3) eV. A flexible visible light photodetector was fabricated via deposition of core-shell C@Bi2S3 nanoflakes onto interdigitated electrodes made of a highly conductive PDMS/CNT composite. The nonlinear current-voltage characteristics of device were observed suggesting the mixed conduction mechanism arising from Ohmic transport and space charge limited current. The enhancement of dark current and photocurrent with the increase of relative humidity (RH) from 40% to 75% was explained by taking into account the Grotthuss mechanism. The remarkable responsivity of 11.5 mA W-1 and the specific detectivity of 1.56 × 1010 Jones were achieved under light illumination with wavelength of 465 nm and intensity of 19.2 μW cm-2 at highest RH. The determined values of specific detectivity and responsivity were found to be competitive or even better than those reported for other photodetectors constructed from Bi2S3. The obtained results clearly indicate that the proposed C@Bi2S3-based device can be used for accurate monitoring of relative humidity and sensitive detection of visible light.

ABSTRACT The chemical transformations of CeO 2 and Ru/CeO 2 catalysts under oxidative treatment (i.e., typical conditions of oxidation reactions on metal/oxide catalysts) were investigated using in situ Raman spectroscopy, and complemented by near‐ambient pressure X‐ray photoelectron spectroscopy (NAP‐XPS). The main attention was focused on the Raman study of the effect of Ru loadinag degree on the structure of CeO 2 support in Ru/CeO 2 catalysts undergoing oxidative treatment. The advances and limitations of Raman spectroscopy for studying the chemical state of Ru/CeO 2 catalysts were systematically investigated and discussed, demonstrating its high potential to monitoring the physicochemical state of ceria support in the Ru/CeO 2 system. The limited applicability of Raman spectroscopy for monitoring the Ru species in Ru/CeO 2 catalyst was also demonstrated.

This article presents the characteristics of titanium matrix composites containing 10 wt

Bimetallic co-catalysts exhibit significantly higher hydrogen photogeneration efficiency compared to their monometallic counterparts. The morphology and shape of nanoparticles also play a crucial role in determining their photocatalytic activity. Previous studies indicate that bimetallic nanoparticles used as co-catalysts were characterized by higher efficiency due to the exposed planes. The shape engineering and impact of Janus-type Pt-Ag co-catalysts remain unexplored. In this study, we report for the first time the design of innovative Janus-type co-catalysts, each consisting of a single platinum nanocube connected to a spherical silver particle of various sizes. A simple and controllable synthesis method for these well-defined structures has been developed. It was demonstrated that the silver content in the Janus structures, used as co-catalysts deposited on the surface of SrTiO3 semiconductors, significantly influences the hydrogen generation efficiency under UV-Vis light. The use of different co-catalysts resulted in varying H-2 photogeneration efficiencies, following the trend: Pt-Ag JNPs (size of Ag similar to 20-50 nm) > Pt-Ag JNPs (size of Ag similar to 60-100 nm) > Pt NPs. Importantly, the developed nanostructures offer dual functionality - not only as efficient co-catalysts for photocatalytic hydrogen production but also as active nanomotors propelled by hydrogen peroxide (H2O2). For the first time, we present real-time observation of their motion using in-situ liquid cell transmission electron microscopy (LC-TEM), allowing precise tracking of their dynamic behavior at the nanoscale.

The chemical transformations of CeO2 and Ru/CeO2 catalysts under oxidative treatment (i.e., typical conditions of oxidation reactions on metal/oxide catalysts) were investigated using in situ Raman spectroscopy, and complemented by near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS). The main attention was focused on the Raman study of the effect of Ru loadinag degree on the structure of CeO2 support in Ru/CeO2 catalysts undergoing oxidative treatment. The advances and limitations of Raman spectroscopy for studying the chemical state of Ru/CeO2 catalysts were systematically investigated and discussed, demonstrating its high potential to monitoring the physicochemical state of ceria support in the Ru/CeO2 system. The limited applicability of Raman spectroscopy for monitoring the Ru species in Ru/CeO2 catalyst was also demonstrated.

Liquid cell transmission electron microscopy (LC-TEM) was used to perform in-situ synthesis of gold nanoparticles (Au NPs) on ceria spherical clusters (ceria SCs) supports. Two experiments were performed: i) dynamic - with a flow of the HAuCl4 solution through the liquid cell, where a fast growth of large, stellated Au NPs was observed in different cell's areas; ii) static - where the liquid cell was filled with the HAuCl4 solution (without flow), resulting in synthesis of Au NPs only in the illuminated area. This allowed us to demonstrate how far reaches the lateral range of the electron beam's interaction within the cell. Additionally, we show differences in the morphology of the Au NPs that were synthesized on the top and the bottom e-chips as a result of the electron beam scattering within the liquid layer of the cell. The associated effect of radical species generation inside the liquid cell by the electron beam was also investigated - at high dose rates and low gold solution flow rates, high concentration of radical species is generated leading to dissolution of the ceria SCs. High flow rates of the HAuCl4 solution drive the growth of large Au NPs with ceria SCs remaining intact.

A comprehensive molecular-level characterization of the surface chemistry of Ru/CeO2 was performed using FTIR spectroscopy of two complementary probe molecules: CO, the most commonly used IR probe for cationic and metal sites, and 15N2, an inert molecule that selectively detects only the strongest adsorption centers. Blank experiments with bare ceria octahedra were also performed. The effects of oxidative and reductive pretreatments on CO and 15N2 adsorption were systematically examined for both Ru/CeO2 and CeO2. The results show that the oxidized catalyst contains an oxidized Ru-oxide/hydroxide phase covering the metal particles and part of the support surface, thus completely blocking metallic ruthenium sites and markedly reducing the number of available CO adsorption sites on ceria and completely suppressing 15N2 adsorption. This blocking effect is much more pronounced on the highly reactive {110} and {100} facets than on the more stable {111} surface. After reduction, metallic Ru becomes exposed, and some previously inaccessible ceria sites are restored. Structural and electronic characterization using XRD, STEM, H2-TPR, and NAP-XPS provides key complementary information on the morphology, composition, reducibility, and chemical state of the catalysts, enabling consistent interpretation of the IR spectroscopic results.

Recently, growing interest has been observed in using calcium as an effective catalyst for graphitizing disordered carbon materials derived from biomass and bioprecursors, such as cellulose and lignin, at relatively low temperatures (<2000 degrees C). Herein, it is demonstrated that in the presence of elements - such as calcium, silicon, sulfur, and potassium, which are abundant in banana peel composed of cellulose and lignin base, graphitization occurs much more effectively. The addition of external calcium source, in the form of calcium carbonate, to the banana peel-derived carbon and heat-treatment of the mixture under protective atmosphere up to 1750 degrees C results in a significant increase in the degree of the graphitization order and local formation of graphite crystals, whereas the same preparation and heat-treatment procedure applied to carbon material derived from pristine cellulose does not lead to such effective graphitization. It is indicated that the graphitization of banana peel carbon occurs due to the synergistic effect of the external Ca-based catalyst and the internal elements present in the raw biomass, supporting the transformation of the disordered graphene-like layers into graphitic structures. These findings are important for the future production of green graphite from biomass.

In this work, we present the first quantitative evaluation of biological light sources, including fluorescence from UV-excitable Green Fluorescent Protein (GFPuv), the luciferin-luciferase system, and bioluminescent Vibrio harveyi, as irradiation sources for ZnIn2S4 (ZIS)-based photocatalysts for hydrogen generation. Dedicated photoreactor prototypes were developed to improve photon transfer and light coupling between biological emitters and photocatalytic systems, enabling quantitative assessment of the engineering feasibility of biologically driven photocatalysis. A highly active visible-light photocatalyst (7.5% Cu-doped ZnIn2S4 modified with 0.5% Pt nanoparticles) achieved a hydrogen evolution rate of 25.8 mmol g−1 h−1 under visible-light irradiation (λ > 420 nm), while the apparent quantum efficiency (AQE) reached 2.7% at 320 nm and 2.6% at 400 nm. The cultivation conditions of GFP-tagged Vibrio harveyi were optimized, resulting in a maximum bioluminescence emission power of 0.45 μW. Furthermore, the minimum light intensity required to initiate photocatalytic hydrogen evolution was experimentally determined to be approximately 20 μW, revealing a significant photon flux gap between biological emission and photocatalyst activation requirements. This work establishes, for the first time, quantitative engineering criteria for biologically driven photocatalytic systems, including spectral matching between emission and photocatalyst absorption, minimum excitation thresholds, emission stability, and efficient photoreactor design for effective photon utilization.

In this study, a new series of PCN-222-based photocatalysts was synthesized using the Cu2+ modification method after synthesis, achieving photocatalytic activity in ultraviolet and visible light. The development of an effective post-synthesis strategy for modifying PCN-222 with copper, which allows for controlled morphology and is less costly, is a novel approach in this work. In addition, for the first time, the formation of hexagonal pores through the combination of Zr-SBU (secondary building units) with porphyrin was observed in detail using a transmission electron microscope. The mechanism by which Cu2+ binds to porphyrins in metal-organic frameworks (MOFs) and on the surface of MOFs in the form of oxides has been thoroughly investigated. It is noteworthy that the most active photocatalyst, PCN-222 (Cu75), showed excellent performance in the photoreduction of CO2 to HCOOH, achieving a conversion rate of 92.8 & micro;mol g-1h-1 and a quantum yield of 1.58% at 400 nm. A mechanism for the excitation and photoconversion of CO2 to HCOOH was proposed, which was confirmed using 13CO2 and supported by theoretical studies to determine the band edge levels. The innovative and rapid approach presented in this study represents a significant step towards the efficient production of clean energy.

Extended producer responsibility (EPR) and the circular economy can address the growing challenge of managing wood-based waste in the context of sustainability. This research explores pyrolysis as an effective method for converting wood-based waste, i.e., bamboo flooring (BF) and high-density fiberboard floor panels (HDF), into valuable products, particularly char. Char samples were activated through two distinct methods: (1) thermal activation at 700 and 850 °C and (2) chemical activation with KOH. Analytical techniques, including elemental and heavy metals analysis, FTIR, Raman spectroscopy, SEM, and TEM were used to assess the chemical composition and surface characteristics of the produced chars. Elemental analysis showed a notable rise in the amount of carbon to 81% and 75% in BF and HDF, respectively. The nitrogen content was relatively high in HDF at 5.12%. Heavy metals analysis revealed total metal contents ranging from 3632 to 9494 ppm in BF chars and 1717 to 7426 ppm in HDF chars. Raman spectra exhibited characteristic D and G bands, with ID/IG ratios of 0.83 for BF and 0.85 for HDF after activation. SEM and TEM analyses revealed heterogeneous porous structures with dominant carbon elements. The high carbon content, low toxicity, and advantageous elemental composition of the chars make them suitable for environmental applications.

Complementary structure (powder XRD and STEM), reducibility (NAP-XPS and H2-TPR), and luminescence studies of Eu-doped ceria nanocrystals of 11-102 nm in size have allowed to determine the advances and limitations of a new luminescence-based technique for fast remote monitoring of the Ce3+/Ce4+ ratio in ceria-based materials-a key factor in determining the functional properties of the CeO2-based group of catalysts. In addition, the combination of SEM-EDS and UHV-XPS studies indicated the presence of segregation of Eu on the surface of ceria nanoparticles, which significantly affects the photoluminescence properties of the CeO2:Eu nanocrystals.

Strontium titanate (SrTiO3) perovskite is a promising photocatalyst for hydrogen evolution, a critical process for green energy production. The efficiency of photocatalytic H2 generation can be significantly enhanced through surface modification with noble metals, where the particle size and distribution play a crucial role. In this study, SrTiO3 particles of two distinct size ranges - small (30-75 nm, close to cubic) and large (250-650 nm, cubic) were modified with silver (Ag) and gold (Au) using a straightforward chemical reduction method. By adjusting reaction parameters such as precursor quantity, temperature, and reaction time, diverse metal-semiconductor structures were synthesized, including Janus-like particles, multi-headed structures, and particles with fine metal coatings. The most active sample (consisting of small SrTiO3 nanoparticles with shape close to cubic, covered with tiny silver particles) exhibited a photocatalytic activity nearly six times higher than that of unmodified SrTiO3. This work demonstrates that specific Ag modification of SrTiO3 is an effective strategy to improve photocatalytic performance, providing valuable pathways for sustainable hydrogen production.

The interplay between structure, microstructure and magnetism driven by calcination in NZFO/f-MWCNTs composites based on 2 wt% of Ni0.5Zn0.5Fe2O4 (NZFO) nanoparticles and functionalized multi-walled carbon nanotubes (f-MWCNTs) synthesized via ex-situ method is discussed. The applied multi-step calcination revealed the structural and microstructural modification. The NZFO spinel ferrite cubic structure is preserved in all composites with a crystallite size increase from about 12 nm to 22 nm. The agglomerated NZFO are broken by high-temperature annealing. The microstructure of nanotubes is changed, revealing a partial nanoonion formation. The distribution of nanoparticle size influences the nanocomposite magnetic performance. The hysteresis loops squareness parameter proved the occurrence of non-interacting single-domain nanoparticles regardless of the synthesis step. The XPS spectra and Raman spectroscopy showcased the temperature-driven redistribution of Fe cations over tetrahedral and octahedral sites. The influence of Fe-based carbon matrix residues on the emergence of the reinforced goethite nanoparticles at the last annealing stage was detected.

The primary goal of this study was to assess the suitability of the proposed method for modifying the surface of cobalt alloys in dental prosthetics, taking into account the specific characteristics of the stomatognathic system during long-term use and their impact on physicochemical properties and the adhesion of cariogenic bacteria such as Streptococcus mutans. Technological factors influencing the quality of the product and its final dimensional characteristics were considered, confirming or ruling out the possibility of iatrogenic errors (related to poorly shaped prostheses) occurring during laboratory fabrication. This study demonstrates that atomic layer deposition of ZrO2 on CoCr dental alloys results in a chemically stable, uniform, and protective surface layer, reducing ion release and improving surface quality. These improvements address key safety and performance requirements outlined in MDR 2017/745, supporting the use of ALD as a state-of-the-art technique for functionalizing dental prosthetic devices. Such coating development may influence the final quality of the denture and also verify its suitability for use in the oral environment (reducing the likelihood of denture stomatitis).

An analysis of defects creation in the vicinity of the selector-root connection plane in single-crystalline turbine blades made of CMSX-4 Ni-base superalloy was performed using several experimental methods. A coupling of scanning electron microscopy and X-ray diffraction topography allowed the visualization of dendritic arrays and surface defects in the root part of the blades. As a result, contrast inversions and areas where internal stresses occur were observed. The defects on a microscopic scale were characterized using positron annihilation lifetime spectroscopy and transmission electron microscopy. The registered positron lifetimes, above 0.5 ns, beyond the range characteristic for defects generally reported in metals and their alloys suggest the presence extremely large void type defects. Herein, we have identified large defects, ca. 2–5 nm in diameter, formed due to the contraction of fluid metal, captured in inter-dendritic regions during the liquid-to-solid transition. This work is a precursor to the almost untouched area of the discussion of lifetimes characteristic for positron bound states, called positronium (>0.5 ns) in relation to the morphology of void-type defects in single-crystalline superalloys.

The presented study strives to further the knowledge of materials for battery technologies based on the first alkali metal ions: lithium, sodium, and potassium. The primary aim of the discussed research was to assess the possibility of creating a universal anode material for those three battery chemistries and investigate the insertion process of different ions in that material. The proposed active material is shungite, a naturally occurring carbon-rich mineral whose turbostratic structure was demonstrated by TEM microscopy. The lithium and potassium-based batteries achieved a similar initial capacity of ∼160 mAh g−1 and were able to retain 147 and 133 mAh g−1 after 50 cycles, respectively. The discharge capacity of sodium battery was only 55 mAh g−1 but the capacity retention and cycle stability were satisfactory, which indicates that the low value is related to the mixed mechanism of sodium ion insertion/adsorption in the macroporous material instead of the degradation of the sodiated material over time. It was revealed that the purification process assisted with an ultrasound treatment develops the specific surface area of shungite and removes sulfur-based impurities. Such treatment significantly lowers the total cell impedance and enhances the battery cycling stability.

Proton-exchange membrane fuel cells are one of the most promising energy conversion technologies for both automotive and stationary applications. Scientists are testing a number of solutions to increase the durability of cells, especially catalysts, which are the most expensive component. These solutions include, among others, the modification of the composition and morphology of supported nanoparticles, the platinum–support interface, and the support itself. A detailed understanding of the mechanism of platinum degradation and the subsequent improvement of the durability of the entire cell requires the development of methods for effectively monitoring the behavior of catalytic nanoparticles under various cell operating conditions. The Identical-Location Transmission Electron Microscopy (IL-TEM) method makes it possible to visually track structural and morphological changes in the catalyst directly. Because the tests are performed with a liquid electrolyte imitating a membrane, they provide better control of the degradation conditions and, consequently, facilitate the understanding of nanoparticle degradation processes in various operating conditions. This review is primarily intended to disseminate knowledge about this technique to scientists using electron microscopy in the study of energy materials and to draw attention to issues related to the characterization of the structure of carbon supports.