Publikační činnost Centra nanotechnologií / Publications of Nanotechnology Centre (9360)

Permanent URI for this collectionhttp://hdl.handle.net/10084/64663

Kolekce obsahuje bibliografické záznamy publikační činnosti (článků) akademických pracovníků Centra nanotechnologií-CNT (9360) v časopisech registrovaných ve Web of Science od roku 2003 po současnost.
Do kolekce jsou zařazeny:
a) publikace, u nichž je v originálních dokumentech jako působiště autora (adresa) uvedena Vysoká škola báňská-Technická univerzita Ostrava (VŠB-TUO),
b) publikace, u nichž v originálních dokumentech není v adrese VŠB-TUO uvedena, ale autoři prokazatelně v době jejich zpracování a uveřejnění působili na VŠB-TUO.

Bibliografické záznamy byly původně vytvořeny v kolekci Publikační činnost akademických pracovníků VŠB-TUO, která sleduje publikování akademických pracovníků od roku 1990.

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Now showing 1 - 20 out of 798 results

Thermodynamic and multi-step kinetic analysis of slow pyrolysis of natural rubber-silanised cellulose composites with 30-55 phr filler content
(Elsevier, 2026) Dobrovská, Jana; Skalková, Petra; Iudina, Elizaveta; Holešová, Sylva; Kawuloková, Monika; Janík, Róbert
Pyrolysis is a promising thermochemical process for waste reduction and energy recovery. Natural rubber (NR) composites filled with 30, 45, and 55 phr silanised cellulose (CELS) were prepared and characterised by SEM and FTIR techniques. Thermogravimetric curves for heating rates of 2, 4, 6, 8, 10, and 20 °C·min−1 were measured in an inert gas. Kinetic parameters were determined by isoconversional kinetic analysis using the Friedman model-free method and a model-based method. By applying the generalised master plot method, it was found that the pyrolysis process follows an autocatalytic mechanism involving two kinetically independent, parallel pathways, each pathway consisting of two sequential steps. The results show that silanisation of cellulose has a positive effect on composite thermal stability, but only up to a specific content of CELS. At high loadings, the resulting silica-rich ash can act as a solid acid catalyst, accelerating secondary cracking reactions during pyrolysis. Innovative approaches for determining the formal thermodynamic parameters have been presented. The first method is based on the Eyring equation and the knowledge of Eα = f(α) and Aα = f(α) from the model-free method, providing the thermodynamic parameters as a function of the entire conversion range, α. The second method is based on the results of model-based kinetic analysis. The method makes it possible to determine these parameters for individual steps of a multi-step model and, thus, to compare the energy demand, spontaneity, and change in disorder of the system in the transition state for these steps.
Nickel-catalyzed reductive hydrolysis of nitriles to alcohols
(Wiley, 2025) Kuloor, Chakreshwara; Goyal, Vishakha; Zbořil, Radek; Beller, Mathias; Jagadeesh, Rajenahally V.
Nitriles are an abundant class of compounds that are widely used as versatile feedstocks to produce variouschemicals including pharmaceuticals, and agrochemicals as well as materials. Here we report Ni-catalyzed reductivehydrolysis of nitriles to alcohols in the presence of molecular hydrogen. This conversion likely occurs in a dominoreaction sequence that first involves the hydrogenation of nitrile to primary imine, then the hydrolysis of imine, andsubsequent deamination to the aldehyde, which is finally hydrogenated to the desired alcohol. Crucial for this reductivehydrolysis process is the commercially available triphos-ligated Ni-complex that enables highly efficient and selectivetransformation of aromatic, heterocyclic, and aliphatic nitriles including fatty nitriles to prepare functionalized primaryalcohols. Further, the synthetic applicability of this Ni-based protocol is presented for the selective conversion of nitrileto alcoholic group in structurally diverse and complex drug molecules as well as agrochemicals. The resulting products,alcohols are indispensable chemicals commonly used in organic synthesis and life sciences as well as material and energytechnologies.
Roman cement mortar prepared by a multi-stage mixing process
(Consejo Superior de Investigaciones Científicas, 2025) Daňková, Jana; Mec, Pavel; Gabor, Roman; Bujdoš, David; Majstríková, Tereza; Valentová, Adéla; Šafrata, Jiří
Roman cement is the predecessor to modern Portland cement. Nowadays, it is a very promising product with lower CO2 emissions, frequently used to restore historical objects. However, there are still many practical problems as a setting that can be affected in several ways. One possibility is the multistage mixing of fresh mortar, a practical historical method that has not yet been scientifically investigated. This article presents an experimental study investigating the effect of multistage mixing on the properties of fresh and hardened mortar. The properties and structure of the mortar were compared with a reference mortar (retardened by citric acid). Multistage mixing affects fresh mortars with optimal consistency and a workability time of 120 minutes. The influence of mixing on the hydration process and structural formation is characterized by isothermal calorimetry and SEM. Comparison of reference and modified mixing mortars exhibits differences in hydration process, structure, and initial strength, but no significant effect at 90 days strength.
Mass transport limitations in plasmonic photocatalysis
(American Chemical Society, 2024) Henrotte, Olivier; Kment, Štěpán; Naldoni, Alberto
The interpretation of mechanisms governing hot carrier reactivity on metallic nanostructures is critical, yet elusive, for advancing plasmonic photocatalysis. In this work, we explored the influence of the diffusion of molecules on the hot carrier extraction rate at the solid-liquid interface, which is of fundamental interest for increasing the efficiency of photodevices. Through a spatially defined scanning photoelectrochemical microscopy investigation, we identified a diffusion-controlled regime hindering the plasmon-driven photochemical activity of metallic nanostructures. Using low-power monochromatic illumination (<2 W cm(-2)), we unveiled the hidden influence of mass transport on the quantum efficiency of plasmonic photocatalysts. The availability of molecules at the solid-liquid interface directly limits the extraction of hot holes, according to their nature and energy, at the reactive spots in Au nanoislands on an ultrathin TiO2 substrate. An intriguing question arises: does the mass transport enhancement caused by thermal effects unlock the reactivity of nonthermal carriers under steady state?
A comparison of non-destructive defect detection methods for steel wire ropes
(MM Science, 2024) Lesňák, Michal; Kroupa, Jan; Barčová, Karla; Miškay, Marek; Jursa, Dominik
Steel wire ropes are among the essential technical elements widely used in many industries. The impeccable condition of these elements has a major impact on the safety of entire facilities where they are applied, be it construction, mining, agriculture, transport, engineering or another area. This article focuses on comparing two non-destructive methods designed to study the internal defects of steel wire ropes. They are defectoscopes with different principles of operation, namely the MID-3 magnetic defectoscope with both excitation and detection of the magnetic field by means of induction coils, and the REMA defectoscope with Hall sensors. Four reference samples of steel wire ropes used in underground mines with well-defined defects corresponding to damage due to fatigue of the wire rope material were created for the study. Based on the experiments performed, it was confirmed that defectoscopes working on the principle of Hall sensors can detect metal cross section loss adequately.
Microwave pyrolysis-prepared engineering carbons from corn cobs and red mombin seeds towards xylene adsorption
(Elsevier, 2024) Matějová, Lenka; Vaštyl, Michal; Jankovská, Zuzana; Cichoňová, Petra; Peikertová, Pavlína; Šeděnková, Ivana; Cruz, Gerardo Juan Francisco; Veliz, Jose Luis Solis; Kania, Ondřej
High-quality biochars/activated carbons were prepared, optimizing individual parameters of energetically-save microwave pyrolysis (raw material loading - 20 vs. 60 g, nitrogen atmosphere - flow vs. batch, ZnCl2 activation) from two agricultural wastes - corn cobs, red mombin seeds. Most promising carbons were examined for gaseous xylene adsorption and showed higher sorption capacity (similar to 250-475 mg(xylene) g(-1)) than commercial carbon (similar to 214 mg(xylene) g(-1)). ZnCl2 activation of both raw materials reduces the fixed carbon content and increases volatiles in activated carbon, suggesting microwave pyrolysis of activated feedstock should take 25 min. While biochars are microporous materials with inhomogeneous low-surface mesopore/macropore network, activated carbons are highly microporous-mesoporous. ZnCl2 activation of both raw materials contributes to formation of extensive high-surface mesopore network (with pore-size < 20 nm) and enlargement of micropore-size, but does not affect the micropore volume. ZnCl2 activation increases H-2 and decreases CH4 production. Microwave pyrolysis of larger raw material loading with ZnCl2 leads to CO2 increase. Best xylene adsorption capacity (475 mg(xylene) g(-1)) was determined for activated carbon produced from 60 g loading of corn cobs in batch nitrogen atmosphere, showing the largest micropore volume, lowest surface polarity and medium rate of graphitization. Large micropore volume, low surface polarity and high rate of graphitization of carbon are xylene sorption capacity-determining factors.
A general atomically dispersed copper catalyst for C–O, C–N, and C–C bond formation by carbene insertion reactions
(Elsevier, 2024) Wang, Qiang; Qi, Haifeng; Ren, Yujing; Cao, Zhusong; Junge, Kathrin; Jagadeesh, Rajenahally V.; Beller, Matthias
The implementation of heterogeneous catalysts in advanced organic synthesis provides basis for the sustainable and cost-effective preparation of pharmaceuticals, agrochemicals, and other structurally complex molecules. Crucial for such applications is the design of appropriate catalytic materials with high selectivity and functional group compatibility. Although many homogeneous catalysts are well known for this purpose, heterogeneous ones, specifically those based on non -noble metals, are scarce. Here, we present the preparation and wide-ranging applications of a specific atomically dispersed copper catalyst for highly selective carbene insertion reactions of diazo compounds with alcohols, phenols, amines, thiols, and N -heterocycles. The optimal catalyst (Cu-NC/Al 2 O 3 ) contains Al 2 O 3 -supported copper -based single atoms coordinated with nitrogen species, which can be conveniently prepared by the pyrolysis of Cu-MOF-303. The resulting catalyst allows for the selective formation of C-O, C-N, and C-C bonds in functionalized and structurally diverse molecules (e.g., complex natural products and drugs), including highly sensitive alkynes and azides.
Influence of the chemical composition of leachates on the results of ecotoxicity tests for different slag types
(Elsevier, 2024) Pavlovský, Jiří; Seidlerová, Jana; Pěgřimočová, Zuzana; Vontorová, Jiřina; Motyka, Oldřich; Michalska, Monika; Smutná, Kateřina; Roupcová, Petra; Novák, Vlastimil; Matějka, Vlastimil; Vlček, Jozef
In this study, four ecotoxicological tests on Vibrio fischeri bacteria, Sinapis alba L. (white mustard), Daphnia magna S. (daphnia's) and earthworms were performed for three types of aqueous slag (ladle, blast furnace and converter) leachates with two-grain sizes (<4 mm, <10 mm). Concentrations of toxic elements and concentrations of Cr(VI), Ca, Na, Al, and other ions were determined. The raw slags were analyzed using X-ray fluorescence spectroscopy (XRFS), and major substances were determined by X-ray powder diffraction (XRD). The aqueous slag leachates passed ecotoxicological tests and met the required criteria, showing no toxicity to Vibrio fischeri and complying with white mustard test criteria. According to the results of the ecotoxicity tests with daphnia, the blast furnace slag samples were not ecotoxic, while two other slag samples were found to be entirely compliant. Characterization of the slags showed that the effect of element/ion leachability and slag grain size is essential. Biplot principal component analysis (PCA) showed that grain size does not significantly affect the separation of individuals on the plane. A positive correlation on toxicity was found with pH, conductivity, calcium content, dissolved content, salinity and fluoride concentration, whereas a negative correlation was found with magnesium concentration, dissolved organic carbon and potassium concentration. The effective concentration at 50% inhibition (EC50) value for Vibrio fischeri correlated with the first dimension of bivariate assessment. In summary, it was found that the investigated slags can be effectively reused as they comply with regulations and do not endanger the environment.
Transverse cracking signal characterization in CFRP laminates using modal acoustic emission and digital image correlation techniques
(Elsevier, 2024) Šofer, Michal; Cienciala, Jakub; Šofer, Pavel; Paška, Zbyněk; Fojtík, František; Fusek, Martin; Czernek, Pavel
The process of formation and subsequent propagation of transverse cracks in 90 degrees plies of carbon-fiber laminated composites was studied using modal acoustic emission approach and digital image correlation techniques. The results from modal acoustic emission approach, which included a newly developed processing tool for acoustic emission waveforms, provided information for identification and subsequent characterization or localization of signals originating from transverse cracking by analysis of the separated flexural and extensional Lamb wave modes in terms of their modal parameters. The digital image correlation method served as a verification tool of the acoustic emission data outputs in the terms of activity of significant localized events originating from the formation of the transverse crack in the 90oply. This made it possible to specify more locally the accompanying activity belonging to the formation or propagation of the magistral transverse crack. The manuscript also presents results related to the evolution of flexural/extensional wave modal parameters as the function of loading force for both [0/0/0/90]S and [90/0/0/0]S panels. It can be concluded that the detection of transverse cracks requires the need for applying a more complex acoustic emission data analysis methodology, while the standard parametric analysis, including the waveform peak frequency, is not sufficient. The presented methodology may serve as a basis for development of robust analysis tool capable of detecting the investigated phenomena.
Effect of milling atmosphere on stability and surface properties of ZnO/vermiculite hybrid nanocomposite powders
(Elsevier, 2024) Čech Barabaszová, Karla; Holešová, Sylva; Kupková, Jana; Hundáková, Marianna; Simha Martynková, Gražyna; Plesník, Lukáš; Basiaga, Marcin
The zinc acetate dihydrate and anhydrous zinc chloride were used as precursors for the sonochemical preparation of the zinc oxide/vermiculite and organically modified zinc oxide/vermiculite_chlorhexidine nanocomposite materials. The nanocomposites were mechanically processed via a high-energy ball milling for 30 min at 300 rpm using two types of atmospheres an air or a nitrogen. Changes in temperature and pressure inside the grinding vessels were measured during mechanical processing in an air atmosphere. The ZnO(Cl)/V_30/300 sample reached the highest pressure (1161 mbar) and temperature (30.3 degrees C) in the milling vessels and for the ZnO(ac)/V_CH_30/300 sample the highest temperature difference was measured at the beginning and at the end of the milling (7 degrees C). The phase transformation, chemical composition and particle size of the hybrid nanocomposite materials were investigated using X-ray diffraction method, Fourier-transform infrared spectroscopy, X-ray fluorescence spectroscopy, carbon phase analysis and particle size distribution analysis. Changes in morphology and particle arrangement were characterised using scanning electron microscopy. The effect of mechanical processing in a protective atmosphere on surface properties such as specific surface area, surface conductivity and zeta-potential were demonstrated in relation to the type of precursor used for the preparation of ZnO nanoparticles in the structure of hybrid nanocomposite materials.
Enhanced detection of heavy metal ions using Ag nanoparticles and single-walled carbon nanotubes within Cu-based metal-organic frameworks
(Elsevier, 2024) Bodkhe, Gajanan A.; More, Mayuri S.; Umar, Ahmad; Ibrahim, Ahmed A.; Siva, Subramanian; Deshmukh, Megha A.; Ingle, Nikesh N.; Gaikwad, Dhammajyot K.; Tsai, Meng-Lin; Hianik, Tibor; Kim, Myunghee; Shirsat, Mahendra D.
Heavy metal ions (HMIs) are major water pollutants, and their toxicity for humans is a great concern for scientists and environmentalists. They are harmful to health even at trace levels; therefore, identifying and removing heavy metals from water is critical. Herein, we report highly selective and sensitive multi-analyte detection of HMIs in water using an electrochemical sensor probe based on Ag nanoparticles and singlewalled carbon nanotubes incorporating copper benzene tri-carboxylate metal -organic frameworks (Ag/ SWNTs@CuBTC-MOFs). The materials were characterized using FTIR, XPS, XRD, and FE-SEM with EDX mapping, TEM, TG-DTA, BET surface area, CV, and EIS. The Ag/SWNTs@CuBTC-MOF electrochemical sensor was tested by differential pulse voltammetry over a pH range of 3 -10 for various HMIs. It shows high pH-dependent sensitivity towards Hg 2 + (pH-5.0), Ni 2 + (pH-7.0), and Fe 3 + (pH-10.0) ions and a limit of detection of 1.39 nM, 2.6 nM, and 3.03 nM, respectively. The fabricated sensor probe exhibits high selectivity, good linearity, and a limit of detection below the maximum contamination limit, as the US Environmental Protection Agency suggested.
A mononuclear Fe(III) complex showing thermally induced spin crossover and slow magnetic relaxation with reciprocating thermal behaviour
(Royal Society of Chemistry, 2024) Bridová, Terézia; Rajnák, Cyril; Titiš, Ján; Samoľová, Erika; Tran, Kevin; Malina, Ondřej; Bieńko, Alina; Renz, Franz; Gembický, Milan; Boča, Roman
AC susceptibility measurements of [Fe-III(L-5)(NCSe)] reveal a field supported slow magnetic relaxation. On cooling, the relaxation time of the high-frequency fraction decreases which is a sign of reciprocating thermal behaviour. The relaxation time for the low-frequency mode at T = 2.0 K is as high as tau(LF) = 2.0 s.
Pt single atoms on TiO2 can catalyze water oxidation in photoelectrochemical experiments
(American Chemical Society, 2024) Wu, Si-Ming; Wu, Lu; Denisov, Nikita; Baďura, Zdeněk; Zoppellaro, Giorgio; Yang, Xiao-Yu; Schmuki, Patrik
Photoelectrochemical water splitting on n-type semiconductors is highly dependent on catalysis of the rate-determining reaction of O-2 evolution. Conventionally, in electrochemistry and photoelectrochemistry O-2 evolution is catalyzed by metal oxide catalysts like IrO2 and RuO2, whereas noble metals such as Pt are considered unsuitable for this purpose. However, our study finds that Pt, in its single-atom form, exhibits exceptional cocatalytic properties for photoelectrochemical water oxidation on a TiO2 photoanode, in contrast to Pt in a nanoparticle form. The decoration of Pt single atoms onto TiO2 yields a remarkable current density of 5.89 mA cm(-2) at 1.23 V-RHE, surpassing bare TiO2 (or Pt nanoparticle decorated TiO2) by 2.52 times. Notably, this enhancement remains consistent over a wide pH range. By accompanying theoretical work, we assign this significant enhancement to an improved charge transfer and separation efficiency along with accelerated kinetics in the oxygen evolution reaction facilitated by the presence of Pt single atoms on the TiO2 surface.
Silver-loaded poly(vinyl alcohol)/polycaprolactone polymer scaffold as a biocompatible antibacterial system
(Springer Nature, 2024) Vilamová, Zuzana; Šimonová, Zuzana; Bednář, Jiří; Mikeš, Petr; Cieslar, Miroslav; Svoboda, Ladislav; Dvorský, Richard; Rosenbergová, Kateřina; Kratošová, Gabriela
A chronic nonhealing wound poses a significant risk for infection and subsequent health complications, potentially endangering the patient‘s well‑being. Therefore, effective wound dressings must meet several crucial criteria, including: (1) eliminating bacterial pathogen growth within the wound, (2) forming a barrier against airborne microbes, (3) promoting cell proliferation, (4) facilitating tissue repair. In this study, we synthesized 8 ± 3 nm Ag NP with maleic acid and incorporated them into an electrospun polycaprolactone (PCL) matrix with 1.6 and 3.4 µm fiber sizes. The Ag NPs were anchored to the matrix via electrospraying water‑soluble poly(vinyl) alcohol (PVA), reducing the average sphere size from 750 to 610 nm in the presence of Ag NPs. Increasing the electrospraying time of Ag NP‑treated PVA spheres demonstrated a more pronounced antibacterial effect. The resultant silver‑based material exhibited 100% inhibition of gram‑negative Escherichia coli and gram‑positive Staphylococcus aureus growth within 6 h while showing non‑cytotoxic effects on the Vero cell line. We mainly discuss the preparation method aspects of the membrane, its antibacterial properties, and cytotoxicity, suggesting that combining these processes holds promise for various medical applications.
A review on sustainable iron oxide nanoparticles: syntheses and applications in organic catalysis and environmental remediation
(Royal Society of Chemistry, 2024) Chaudhari, Dinesh S.; Upadhyay, Rohit P.; Shinde, Gajanan Y.; Gawande, Manoj B.; Filip, Jan; Varma, Rajender S.; Zbořil, Radek
Iron oxide nanoparticles have been intensively investigated owing to their huge potential as diagnostic, therapeutic, and drug-carrier agents in biomedicine, sorbents in environmental technologies, sensors of various inorganic and organic/biological substances, energy-generating and storing materials, and in assorted biotechnological and industrial processes involving microbiology, pigment industry, recording and magnetic media or (bio)catalysis. An eminent interest in exploring the realm of iron oxides is driven by their chemical and structural diversity, high abundance, low cost, non-toxicity, and broad portfolio of chemical procedures enabling their syntheses with desirable physicochemical features. The current review article centers its attention on the contemporary advancements in the field of catalysis and environmental technologies employing iron oxides in various chemical forms (e.g., hematite, magnetite, maghemite), sizes (∼10–100 nm), morphology characteristics (e.g., globular, needle-like), and nano archi tecture (e.g., nanoparticles, nanocomposites, core–shell structures). In particular, the catalytic appli cations of iron oxides and their hybrids are emphasized regarding their efficiency and selectivity in the coupling, oxidation, reduction, alkylation reactions, and Fischer–Tropsch synthesis. The deployment of iron oxides and their nanocomposites in environmental and water treatment technologies is also deliber ated with their roles as nanosorbents for heavy metals and organic pollutants, photocatalysts, and hetero geneous catalysts (e.g., hydrogen peroxide decomposition) for oxidative treatment of various contami nants. The associated challenges and potential progress in iron-oxide-based catalytic and environmental technologies are highlighted as well. Young chemists, researchers, and scientists could find this review useful in enhancing the usefulness of nano iron oxides in their investigations and developing sustainable methodologies.
Magneto-plasmonic “switch” device for magnetic field detection
(De Gruyter, 2024) Bsawmaii, Laure; Giraud, Pascal; El Haber, Gerges; Halagačka, Lukáš; Chatelon, Jean-Pierre; Jamon, Damien; Jourlin, Yves; Royer, François
This paper introduces a novel class of low-loss and cost-effective optical planar structures tailored for magnetic detection applications. These structures represent unconventional magneto-plasmonic devices specifically optimized for an 'optical switch' configuration. The structure consists of a 1D deep sinusoidal gold grating covered by a thin cobalt layer. In this unique arrangement, the excited plasmon induces a high-contrast switching phenomenon between the reflected free space intensity of specular (0th) and -1st diffracted orders, sensitive to any transverse magnetic fields applied to the cobalt layer. The use of these two distinct diffracted orders induces differential measurements, effectively mitigating common drift and perturbations. This innovative approach results in an enhanced detection sensitivity, showcasing the potential of these structures for advanced magnetic field sensing applications.
Enhancing photocatalytic g-C3N4/PVDF membranes through new insights into the preparation methods
(Elsevier, 2024) Vilamová, Zuzana; Sampaio, Maria J.; Svoboda, Ladislav; Bednář, Jiří; Šimonová, Zuzana; Dvorský, Richard; Silva, Cláudia G.; Faria, Joaquim L.
Fibrous membranes are crucial on the filtration of pollutants from air and water, but continued use can lead to a failure in effectiveness due to pollutant accumulation. To enhance durability, incorporating photocatalytic submicroparticles into these membranes appear as a solution. Here, we prepared a set of polyvinyl difluoride (PVDF) fibrous membranes modified with graphitic carbon nitride (g-C3N4) using three different methodologies. Their photocatalytic efficiency was investigated using phenol as model pollutant compound under visible light irradiation. Using g-C3N4 fibrous membranes modified by electrospinning blend a pseudo first-order kinetic constant (kapp) of 2.51 x 10-4 min-1 was observed for phenol degradation after 240 min reaction. Despite minimal particle adhesion the thermal treatment increased kapp to 5.41 x 10-4 min-1. The membranes prepared via chemical activation of PVDF exhibited the highest photocatalytic activity (kapp of 21.7 x 10-4 min-1). This superior activity was attributed to covalent bonds between PVDF and g-C3N4, allowing the formation of oxidative species.
Comparative study of photocatalysis with bulk and nanosheet graphitic carbon nitrides enhanced with silver
(Springer Nature, 2024) Michalska, Monika; Pavlovský, Jiří; Simha Martynková, Gražyna; Kratošová, Gabriela; Hornok, Viktória; Nagy, Peter B.; Novák, Vlastimil; Szabó, Tamás
The main goal of this research is to investigate the effectiveness of graphitic carbon nitride (g-C3N4, g-CN) in both bulk and nanosheet forms, which have been surface-modified with silver nanoparticles (Ag NPs), as photocatalysts for the degradation of acid orange 7 (AO7), a model dye. The photodegradation of AO7 dye molecules in water was used to test the potential photocatalytic properties of these powder materials under two different lamps with wavelengths of 368 nm (UV light) and 420 nm (VIS light). To produce Ag NPs (Ag content 0.5, 1.5, and 3 wt%) on the g-CN materials, a new synthesis route based on a wet and low-temperature method was proposed, eliminating the need for reducing agents. The photodegradation activity of the samples increased with increasing silver content, with the best photocatalytic performances achieved for bulk g-CN samples and nanosheet silver-modified samples (with the highest content of 3 wt% Ag) under UV light, i.e., more than 75% and 78%, respectively. The VIS-induced photocatalytic activity of both examined series was higher than that of UV. The highest activities of 92% and 98% were achieved for the 1.5% Ag-modified g-CN bulk and nanosheet materials. This research presents an innovative, affordable, and environmentally friendly chemical approach to synthesizing photocatalysts that can be used for degrading organic pollutants in wastewater treatment.
Overlap and rotate - a simple method for predicting out-of-plane and in-plane orientations of heteroepitaxial thin films
(Elsevier, 2024) Tokarský, Jonáš; Molek, Jonáš
The production of heteroepitaxial thin films is increasingly important due to their considerable utility in technical practice. This usability is determined by their specific physical and chemical properties influenced by the mutual crystallographic substrate-film orientation, both the out-of-plane and the in-plane. The possibility of predicting these orientations would reduce the time and financial burden of their experimental determination. This study shows how the out-of-plane and the in-plane orientation of heteroepitaxial film can be predicted by simply calculating number of overlapping atoms in a system of two overlapping crystallographic planes, one of which rotates relatively to the other. Coordinates of atoms in the crystallographic planes are taken from bulk structures, which contributes to the simplicity of the method. The average number of overlapping atoms (calculated from a 360° rotation) and the maximum number of overlapping atoms (including a corresponding angle) indicate the out-of-plane and the in-plane orientation, respectively. The method is tested on various substrate/film systems (SrTiO3/ZnO, Al2MgO4/ZnO, MgO/ZnO, MgO/CuO, Si/Al, MoS2/Au) and the results are compared with experimental data obtained from the literature. The good agreement with the experimental data shows this method to be reliable and sufficiently accurate for heteroepitaxial thin films.
Defect-mediated energy states in brookite nanorods: Implications for photochemical applications under ultraviolet and visible lkight
(American Chemical Society, 2024) Zollo, Alessia; Liao, Yu-Kai; Hejazi, S. M. Hossein; Shahrezaei, Mahdi; Daka, Mario; Salvadori, Enrico; Livraghi, Stefano; Naldoni, Alberto; Chiesa, Mario
The photochemical properties of brookite nanorods are systematically explored using light-induced electron-paramagnetic resonance (EPR) techniques at different wavelengths spanning the UV-vis region of the electromagnetic spectrum (355-650 nm). Under UV irradiation, electron-hole pairs are generated, leading to the stabilization of paramagnetic centers, primarily Ti3+ and O- species at the surface. Visible light irradiation at low temperature results in a unique pair of EPR signals, including electrons trapped at titanium cations and a distinct signal resonating at g = 2.004. The pair of signals disappears after annealing at room temperature, indicating that recombination pathways with trapped electrons are available. The chemical reactivity of the different photogenerated species is tested using electron and holes scavengers. While peculiar light-harvesting capabilities are observed for the brookite nanorods, experiments carried out in the presence of a hole scavenger indicate a limited potential for oxidative processes under visible light.

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