Centrum pre Nanodiagnostiku Materiálov

Shalu Atri, Hamidreza Behtooei, Mário Kotlár, Frantisek Zazimal, Dana Dvoranova, Tomas Roch, Leonid Satrapinskyy, Tomas Zelenka, Tomas Homola, Olivier Monfort

In: Catalysis Today, Volume 470, 2026, 115764

https://doi.org/10.1016/j.cattod.2026.115764

Abstract

This study demonstrates a simple and scalable synthesis of α-FeOOH (goethite) intercalated Ti₃C₂T_x MXene through TMAOH treatment, targeting efficient degradation of emerging micropollutants in wastewater via an advanced oxidation process (AOP). Such a α-FeOOH-intercalated MXene stabilizes heterogeneous Fenton-based reactions which usually suffer from decreased efficiency over time due to Fe leaching, thus highlighting the novelty of the work. The successful integration of goethite particles in the MXene interlayer space was evidenced by X-ray diffraction (XRD), Fourier-transform infrared spectrometer (FTIR) and Transmission Electron Microscopy (TEM) analysis. X-ray photoelectron analysis (XPS) revealed notable surface oxidation along with minor TiF_x and TiO_2-xF_x impurities formed via TMAOH treatment. Increased concentration of surface functional groups along with enhanced BET area (71.2 m² g⁻¹) and porosity after TMAOH treatment enabled complete degradation of caffeine in ⁓ 90 min, by activation of peroxymonosulfate (PMS) under UVA light. Scavenging experiments, electron paramagnetic resonance (EPR) and XPS analysis indicated the degradation mechanism driven by Fenton-based reactions, electron transfer and interfacial surface charge transfers, with hydroxyl (^•OH) and sulfate () radicals identified as predominant reactive oxygen species (ROS). The assessment of the α-FeOOH-intercalated MXene as stable Fenton catalyst was confirmed with minimal iron leaching (3.07 wt%) during catalytic reactions and robust reusability over ten cycles, thus being more efficient and sustainable than conventional Fenton-based catalysts. Post-reaction XRD,FTIR and TEM analyses further confirmed excellent structural stability of the new catalyst. These findings establish α-FeOOH-intercalated Ti₃C₂T_x MXene as a promising and durable catalyst for heterogeneous Fenton-based reactions applied to wastewaters treatment.

Shalu Atri, Hamidreza Behtooei, Frantisek Zazimal, Arshitha Madhusudhan, Mário Kotlár, Jana Makukova, Andrea Sevcovicova, Tomas Roch, Marcello Brigante, Michael Naguib, Olivier Monfort 

In: Chemical Engineering Journal, 2026, 534, 174993

https://doi.org/10.1016/j.cej.2026.174993

Abstract

The increasing occurrence of pharmaceutical residues in treated wastewaters, together with the emergence of MXene-based composites as novel and promising catalysts for advanced oxidation processes (AOP), motivates the development of more efficient and selective treatment technologies. In this study, a novel Nb₄C₃T_x-Co₃O₄ nanohybrid AOP catalyst was synthesized for peroxymonosulfate (PMS) activation under dark conditions to degrade four pharmaceutical pollutants including caffeine (CAF), ibuprofen (IBU), paracetamol (PAR), and sulfamethoxazole (SMX). Structural and morphological characterization confirmed successful integration of Co₃O₄ nanoparticles onto the Nb₄C₃T_x MXene surface. Under optimized conditions, complete degradation of the pharmaceuticals was obtained within 60 min, except for IBU, which required >100 min due to steric hindrance in its molecular structure, resulting in fewer sites available for attack by reactive species. The contribution of reactive species differs among the pharmaceutical where degradation of IBU and PAR was predominantly governed by sulfate radicals (), contributing over 50% while CAF and SMX followed a degradation mechanism involving singlet oxygen (¹O₂, up to 30%),  (20–40%) and  (20–40%). The AOP involved a redox-mediated PMS activation mechanism predominantly on Co and Nb surface sites. The Nb₄C₃T_x-Co₃O₄ catalyst exhibited robust performance in cocktail of pollutants and maintained satisfactory degradation efficiency, especially for SMX and PAR in tertiary effluents from wastewaters treatment plant (WWTP) collected in Bratislava. In addition, the chemical structure of degradation by-products was characterized by LC-MS analysis and a degradation mechanism was proposed. Colorimetric MTT assays of the treated waters showed no acute cytotoxicity from either the PhACs or their degradation products on short-term exposure. This study provides new insights into pollutant-specific oxidation mechanisms and reactive species profiles in PMS-based AOPs, establishing Nb₄C₃T_x-Co₃O₄ as a promising non-conventional catalyst for potential quaternary treatment in WWTP technology.

O.V. Maksakova, V.M. Beresnev, S.V. Lytovchenko, M. Sahul, Mária Čaplovičová, R.S. Galushkov

In: East Eur. J. Phys., no. 1, pp. 540-547, Mar. 2026

https://doi.org/10.26565/2312-4334-2026-1-62

Abstract:

Multilayer nitride coatings are widely used to improve the mechanical performance and durability of engineering components subjected to severe tribological loading. In the present work, the adhesion behaviour and failure mechanisms of nanolayered TiMoN/NbN multilayer coatings deposited by cathodic arc PVD were investigated as a function of nitrogen working pressure. Two coatings were synthesized at nitrogen pressures of 0.52 Pa and 0.13 Pa under otherwise identical deposition conditions. Microscopy analysis revealed that both coatings exhibit a well-defined nanolayered architecture consisting of alternating TiMoN and NbN layers with a modulation period of approximately 85 nm and a total thickness of about 9.5 μm. The decreasing of nitrogen pressure results in a higher density of macroparticles due to the longer mean free path of cathodic arc plasma species. Scratch adhesion tests performed under progressive loading conditions allowed identification of two characteristic failure events corresponding to buckling crack initiation and buckling spallation. The multilayer coating deposited at 0.13 Pa demonstrated slightly improved resistance to crack initiation (5.41 N) compared with the multilayer coating deposited at 0.52 Pa (4.72 N). However, both coatings exhibited similar values of the second critical load (12.4–12.5 N). The multilayer coating deposited at higher nitrogen pressure mainly undergoes adhesive failure with extensive substrate exposure. In contrast, the multilayer coating deposited at lower nitrogen pressure exhibits predominantly cohesive damage within the multilayer structure. The obtained results demonstrate that nitrogen pressure during cathodic arc deposition significantly affects the microstructure evolution and the mechanisms of adhesion failure in TiMoN/NbN multilayer coatings. The study provides insight into the optimization of deposition parameters for improving the mechanical reliability of multilayer nitride coatings.

Aizhan B. Talipova, Volodymyr Buranych, Irina S. Savitskaya, Inara Abashidze, Fyodor I. Malchik, Dina H. Shokatayeva, Martin Sahul, Krzysztof Rokosz, Mária Čaplovičová, Alexander D. Pogrebnjak

In: ACS Omega 2026, 11, 9, 14806–14820

https://doi.org/10.1021/acsomega.5c11015

Abstract:

The treatment of chronic wounds is critically challenged by resilient biofilms formed by multidrug-resistant (MDR) pathogens, which are largely impervious to conventional antibiotics. This study addresses this challenge by engineering a multifunctional hydrogel dressing that synergistically integrates bacterial cellulose (BC), MXene nanosheets, and hydroxyapatite (HAp). Plays a critical dual role in the composite, significantly boosting bioactivity while also stabilizing the MXene to prevent oxidation and maintain its antibacterial properties. As a result, the BC/MXene/HAp composite achieved a near-total (98%) eradication of viable cells in mature biofilms of challenging MDR pathogens, including MRSA and FQRPA. Such activity is driven by a dual-mechanism that effectively disrupts both the initial attachment of bacteria and the structural scaffold of established biofilms. Complementing this efficacy, in vitro assays with NIH-3T3 fibroblasts confirm that the composite supports excellent cell adhesion, proliferation, and metabolic activity, highlighting its high biocompatibility. This work demonstrates a nonantibiotic strategy to combat biofilms through a synergistically designed biomaterial. Given its robust performance and multifunctionality, this platform is a promising candidate for the development of advanced therapeutic dressings in regenerative wound care.

Martin Ondrejka, Peter Bačík, Juraj Majzlan, Pavel Uher, Štefan Ferenc, Tomáš Mikuš, Martin Števko, Mária Čaplovičová, Stanislava Milovská, Alexandra Molnárová, Christiane Rößler and Christian Matthes

In: Mineralogical Magazine, 2026; 90(1) : 196-197

https://doi.org/10.1180/mgm.2025.10190

Shipra Aswal, Sirsendu Ghosal, Himanshu Murari, Ravinder Chahal, Viliam Vretenár, Ravi Kumar Biroju, Ľubomír Vančo, Subhradip Ghosh and P. K. Giri

In: Nanoscale, 2025

https://doi.org/10.1039/D5NR03668B

Abstract

Understanding phonon transport and thermal anisotropy in two-dimensional (2D) materials is essential for their integration into electronic and thermal nanoscale devices. In this work, we achieve large-area, contamination-free monolayer Rhenium diselenide (ReSe2) growth via chemical vapor deposition, confirmed by atomic force microscopy and HAADF-STEM imaging. To probe its anisotropic thermal properties, we employ non-contact low-temperature Raman spectroscopy with unpolarized laser excitation to measure its thermal conductivity (κ). We report exceptionally low values of in-plane thermal conductivity κ~25.2 Wm-1K-1 for the pristine monolayer, the lowest among the TMDs. Critically, we find the introduction of more selenium vacancies further suppresses it to κ~20.7 Wm-1K-1. Polarization-dependent Raman analysis reveals a layer-dependent change in anisotropy ratio, with the ratio decreasing from 6.23 (pristine monolayer) to 4.42 (monolayer with vacancies) and further to 3.82 (trilayer), highlighting the distinct effects of both interlayer interactions and point defects on phonon transport. The suppression of κ with increasing thickness suggests enhanced phonon scattering from structural distortions and weak van der Waals coupling. These findings provide critical insights into how both layer thickness and intrinsic defects like Se vacancies can be used to modulate anisotropic transport in low-symmetry 2D materials. In addition, we employed Density Functional Theory and Boltzmann Transport Theory to elucidate the lattice phonon dynamics and thermal transport behaviour of monolayer ReSe2. The computed lattice thermal conductivity (κ_l) exhibits excellent agreement (κ_l^x ≈ 21.5 Wm-1 K-1 and κ_l^y ≈ 23.8 Wm-1 K-1) with the experimental data, thereby providing strong validation for our experimental approach. This work establishes ReSe2 as a strong candidate for thermoelectric and nanoelectronic applications where tunable thermal properties are paramount.

Ľubomír Vančo, Ravi K. Biroju, Mário Kotlár, Viliam Vretenár, Dipak Maity, Tharangattu N. Narayanan

In: J. Phys. Chem. C 2025, 129, 47, 20995–21004

https://doi.org/10.1021/acs.jpcc.5c05299

Abstract

Molybdenum disulfide (MoS₂) monolayers have emerged as promising materials for a variety of applications. Their behavior depends critically on surface composition; therefore, careful characterization is necessary to describe their properties accurately. Although Auger electron spectroscopy (AES) is a standard method capable of addressing this issue, it suffers from beam-induced damage and variation of spectral features in complex samples. To overcome these limitations, we employed correlative analysis to examine MoS₂ and V-doped MoS₂ 2D surfaces by using Auger scatterplots. As we demonstrate, this method enables the nondestructive imaging and assessment of the lateral and depth distributions of the elements and provides a remarkably convenient way to estimate S-rich/depleted regions. The scatterplot technique indicates that V doping in MoS₂ retards desulfurization in an Ar/H₂ plasma environment. By reducing the electron dose, the analysis using scatterplots can improve the accuracy of AES by up to 30%. The Auger scatterplot method provides insight into the affinity or independence of surface constituents through quantitative relationships, enabling separate analysis of the characteristic areas within a complex sample. These findings are supported by Raman spectroscopy and transmission electron microscopy, which highlight the effectiveness of the Auger scatterplots and their potential for examining the surfaces of 2D materials. Auger maps also show a strong correlation with photoluminescence features in MoS₂ monolayers, thereby illustrating the overlap with practical applications.

Dipak Maity, Ravi K. Biroju, Viliam Vretenár, Mihir Ranjan, Sahoo, L’ubomír Vančo, Matej Mičušík, Tharangattu N. Narayanan, Kalpataru Pradhan

In:  ACS Appl. Nano Mater. 2025, 8, 47, 22573–22585

https://doi.org/10.1021/acsanm.5c03601

Abstract

Two-dimensional semiconductor-transition-metal dichalcogenide (2D-STMD) based semiconductors have emerged as promising materials for future spintronic and optoelectronic applications, including photodetectors and transistors. Transferring high-quality chemical vapor deposition (CVD)-grown monolayer 2D-STMDs and their alloys to the target substrate is very challenging for fabricating efficient devices. Unfortunately, current post-transfer methods struggle to completely remove unwanted contamination residues during wet-transfer processes, which adversely affects material quality and intrinsic properties. In this work, the effect of ethanol cleaning on the qualitative and quantitative assessment of molecular adsorbates is demonstrated, based on atomic-resolution high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) image analysis supported by X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and density functional theory (DFT) calculations, which showcases ultraclean material structures. We estimate the unidentified molecular adsorbates in the proximity of molybdenum (Mo) and chalcogen (S, Se) atomic sites, which are tentatively assigned as ‘C₂H₅OH (EtOH)’, ‘H₂O’, and ‘O₂’ related adsorbates. The attribution is based on HAADF-STEM Gaussian line shape fitting of atomic intensity columns and corresponding computed adsorption energy values after ethanol treatment of the MoS_2(1–x)Se_2x (MSSE) alloy. In line with experimental observations of persistent OH-containing residues on the surface, DFT simulations show that EtOH has better adsorption on both pristine and sulfur-vacancy MSSE monolayers than H₂O and O₂. Photodetector device measurements revealed a remarkable ∼90% enhancement in photocurrent values for ultraclean samples, significantly boosting the material’s photoresponsivity. DFT calculations on the adsorption energy and density of electronic states were also conducted to validate our experimental findings.

Daniel Truchan, Adriana Hvizdošová Annušová, Guilhem Curé, Matej Mičušík, Vojtech Nádaždy, Mário Kotlár, Giulia C. Fadda, Peter Nádaždy, Matej Jergel, Claire Wilhelm, Aurore Van de Walle, Peter Šiffalovič & Yoann Lalatonne

In: Discover Nano 20, 197 (2025)

https://doi.org/10.1186/s11671-025-04378-5

Abstract

The emergence of novel catalytic, electrochemical, and biomedical applications of nanomaterials requires an understanding of their structural basis for stimuli-responsive performance. The chemistry of polyoxometallic nanomaterials, with a variety of interesting properties, remains poorly explored. In this study, microwave-assisted non-aqueous sol-gel synthesis was used for the first time to prepare nanoparticles based on polyoxomolybdates. Their optoelectronic properties, focusing on laser-triggered photothermal response, were investigated in detail depending on the synthesis temperature. Significant differences were observed between products prepared from the same precursor via a fast protocol by varying the synthesis temperature. Only low-temperature synthesis (≤ 90 °C) yielded near-infrared (NIR) photothermally active MoO_X nanoparticles. The regular packing with large lattice defects of these clusters, along with a low reduction degree, allows water molecules to penetrate and interact with surface Mo = O bonds, forming intermediate electron states within the bandgap. These intermediate electron states are responsible for the NIR laser response suitable for photothermia. Additionally, the NIR response can be modulated in a controlled manner even after synthesis through electrochemical impedance spectroscopy. These findings have direct implications for MoO_X photothermal therapy, targeted defect engineering of polyoxomolybdate structures, and their electrochemical and biological applications.

Abdul Kaium Mia, Sourav Dey, Lubomir Vanco, Viliam Vretenar, P. K. Giri

In: Materials Today Nano 31, 100638 (2025)

https://doi.org/10.1016/j.mtnano.2025.100638

Abstract:

The semiconducting 2D transition metal dichalcogenides (TMDs) have gained substantial attention, though the progress in their lateral heterostructures (HS) and in-situ growth for electronic and optoelectronic applications has been very limited. Herein, we report a single-step in-situ chemical vapor deposition growth of bilayer WS2-MoS2 lateral HS, which ensures a clean diffused interface between WS2 and MoS2, enabling efficient charge transport. The spatial Raman, photoluminescent (PL), and Auger mapping of in-situ WS2-MoS2 lateral HS shows a clear transition from pure WS2 to pure MoS2 region through a graded WS(1-x)MoxS2 alloy interface. The composition and the width of the alloy interface could be tuned by careful choice of the proportion of precursor materials and by tuning the growth parameters. Spatially resolved PL spectra and PL mapping reveal a strongly enhanced (more than one order of magnitude) PL intensity in the HS interface attributed to the strain-induced bandstructure modification in the alloyed interface. Interestingly, the alloyed interface in the lateral HS also dramatically improves the electronic properties, resulting in an on-off ratio of 108 in the fabricated field effect transistor, which is two orders of magnitude higher than their individual counterpart. These results on lateral HS are significant, and they pave the way to synthesize other different HSs for future electronic devices and integrated circuits.