Pokročilé nízkodimenzionální nanomateriály
Browse
Recent Submissions
- ItemBiopolymeric fibers prepared by centrifugal spinning blended with ZnO nanoparticles for the treatment of Acne vulgaris(ELSEVIER, 2024-04-01) Říhová, Martina; Číhalová, Kristýna; Pouzar, Miloslav; Kuthanová, Michaela; Jelínek, Luděk; Hromádko, Luděk; Čičmancová, Veronika; Heger, Zbyněk; Macák, JanAcne vulgaris is a serious dermatological disease affecting a significant part of the population. Currently, available therapeutics are effective only at high concentrations, which has a negative environmental and economic impact. In particular, ZnO nanoparticles (NPs) have a great potential in various biomedical applications due to their specific properties and antibacterial/antiviral activity. In this study, biomedically approved ZnO NPs with distinct diameter were used as the active therapeutic modality to treat acne-causing pathogens. For the first time, we show the utilization of ZnO NPs that were evenly distributed within centrifugally spun fiber carriers. Upon application on the skin, ZnO NPs can sustainably release and have profound antibacterial activity at lower therapeutic concentrations. Fibers were made using innovative centrifugal spinning procedure from natural polymers - gum arabic and pullulan - that are known for their biocompatibility. Different amount of ZnO NPs (from 0.03 to 4.5 wt.% related to the dry mass) was added into the spinning polymer solution, either in a form of a dry powder or as a dispersion containing NPs and isopropyl myristate. The resulting fibers were subsequently characterized for morphology and presence of ZnO NPs by Scanning Electron Microscopy and Energy-Dispersive X-ray fluorescence spectrometry. The materials were thoroughly assessed for their antibacterial activity against Cutibacterium acnes and Staphylococcus epidermidis , which are major opportunistic pathogens causing acne. The combination of two types of nanomaterials, namely active nanoparticles and fiber carriers, proved to be very promising and bear a great potential for the treatment of these diseases.
- ItemLow-Temperature Atomic Layer Deposition Synthesis of Vanadium Sulfide (Ultra)Thin Films for Nanotubular Supercapacitors(WILEY, 2024-04-01) Zazpe Mendioroz, Raúl; Sepúlveda Sepúlveda, Lina Marcela; Rodriguez Pereira, Jhonatan; Hromádko, Luděk; Michalička, Jan; Kolíbalová, Eva; Kurka, Michal; Thalluri, Sitaramanjaneya Mouli; Sopha, Hanna Ingrid; Macák, JanHerein, the synthesis of vanadium sulfide (VxSy) by atomic layer deposition (ALD) based on the use of tetrakis(dimethylamino) vanadium (IV) and hydrogen sulfide is presented for the first time. The (ultra)thin films VxSy are synthesized in a wide range of temperatures (100-225 degrees C) and extensively characterized by different methods. The chemical composition of the VxSy (ultra)thin films reveals different vanadium oxidation states and sulfur-based species. Extensive X-ray photoelectron spectroscopy analysis studies the effect of different ALD parameters on the VxSy chemical composition. Encouraged by the rich chemistry properties of vanadium-based compounds and based on the variable valences of vanadium, the electrochemical properties of ALD VxSy (ultra)thin films as electrode material for supercapacitors are further explored. Thereby, nanotubular composites are fabricated by coating TiO2 nanotube layers (TNTs) with different numbers of VxSy ALD cycles at low temperature (100 degrees C). Long-term cycling tests reveal a gradual decline of electrochemical performance due to the progressive VxSy thin films dissolution under the experimental conditions. Nevertheless, VxSy-coated TNTs exhibit significantly superior capacitance properties as compared to the blank counterparts. The enhanced capacitance properties exhibited are derived from the presence of chemically stable and electrochemically active S-based species on the TNTs surface.
- ItemA road for macroporous silicon stabilization by ultrathin ALD TiO2 coating(ROYAL SOC CHEMISTRY, 2024-11-25) Al Chimali, Bachar; Carrasco, Irene; Defforge, Thomas; Dailleau, Romain; Monier, Lisa; Baishya, Kaushik; Macák, Jan; Gautier, Gael; Le Borgne, BriceMacroporous silicon films have great potential for a plethora of applications in optoelectronics and microelectronics. However, such layers are too electrically and chemically unstable to be used in fuel cells, supercapacitors or any devices requiring the use of an electrolyte. This is due to their high surface-to-volume ratio, which makes them prone to chemical reactions, such as photo-oxidation, especially in aqueous media. In this work, we investigated how to exploit the capabilities of macroporous silicon while avoiding its oxidation. To do so, we explored the influence of ultrathin TiO2 films by atomic layer deposition (ALD) onto the walls of silicon macropores, created by electrochemical etching from n-type wafers. Using microscopy and optical analysis, we demonstrate the achievability of ALD coating on macroporous silicon, as well as the stability of these films against oxidation. In particular, we show that 5 ALD cycles that correspond to less than 1 nm thin coating are sufficient to passivate the silicon surface. The coated and uncoated layers were analyzed and compared before and after exposure to water and sunlight. The monitoring of the Si-O-Si band area evolution over 29 days gave no evidence of photo-corrosion. In addition, the wettability of the samples did not change after functionalization. Finally, to investigate the oxidation prevention for photocatalytic applications, we showed that methylene blue degradation rates were significantly increased (by 50% on average) for 10 nm TiO2 ALD-coated porous silicon samples when compared to natural degradation. Interestingly, layers thinner than 1 nm also showed enhanced catalytic kinetics for short times (t < 40 min).
- ItemEnhancing Alkaline Hydrogen Evolution Reaction on Ru-Decorated TiO2 Nanotube Layers: Synergistic Role of Ti3+, Ru Single Atoms, and Ru Nanoparticles(Wiley, 2025-05-01) Thalluri, Sitaramanjaneya Mouli; Rodriguez Pereira, Jhonatan; Michalička, Jan; Kolíbalová, Eva; Hromádko, Luděk; Šlang, Stanislav; Pouzar, Miloslav; Sopha, Hanna Ingrid; Zazpe Mendioroz, Raúl; Macák, JanSynergistic interplays involving multiple active centers originating from TiO2 nanotube layers (TNT) and ruthenium (Ru) species comprising of both single atoms (SAs) and nanoparticles (NPs) augment the alkaline hydrogen evolution reaction (HER) by enhancing Volmer kinetics from rapid water dissociation and improving Tafel kinetics from efficient H* desorption. Atomic layer deposition of Ru with 50 process cycles results in a mixture of Ru SAs and 2.8 +/- 0.4 nm NPs present on TNT layers, and it emerges with the highest HER activity among all the electrodes synthesized. A detailed study of the Ti and Ru species using different high-resolution techniques confirmed the presence of Ti3+ states and the coexistence of Ru SAs and NPs. With insights from literature, the role of Ti3+, appropriate work functions of TNT layers and Ru, and the synergistic effect of Ru SAs and Ru NPs in improving the performance of alkaline HER were elaborated and justified. The aforementioned characteristics led to a remarkable performance by having 9 mV onset potentials and 33 mV dec(-1) of Tafel slopes and a higher turnover frequency of 1.72 H-2 s(-1) at 30 mV. Besides, a notable stability from 28 h staircase chronopotentiometric measurements for TNT@Ru surpasses TNT@Pt in comparison.
- ItemComparative Analysis of Thermal Activation on Felts and Continuous Carbon Filament Electrodes for Vanadium Redox Flow Batteries(WILEY-V C H VERLAG GMBH, 2024-11-04) Noemí Aguiló Aguayo, Noemí; Ebert, Toni Alena; Amade, Roger; Bertran, Enric; Ospina, Rogelio; Rodriguez Pereira, Jhonatan; de Leon, Carlos Ponce; Bechtold, Thomas; Pham, TungThermal treatments are commonly used to improve electrode kinetics in vanadium redox flow batteries (VRFB). The impact of the widely adopted thermal treatment-400 degrees C for least 24 hours-was investigated on polyacrylonitrile (PAN)-based continuous carbon filaments (tows) and compared to PAN-based graphite felts. Surface properties were assessed with scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and wettability measurements. The electrode activity was investigated via electrochemical impedance spectroscopy (EIS). Charge-transfer resistances and the constant phase element parameters related to the electric double layer were determined, revealing a correlation between enhanced electrode activity and increased double layer across all electrodes. An 8-hour 400 degrees C thermal treatment was sufficient to improve electrode activity for tows, whereas felts required longer durations, up to 24 hours, attributed to differences in the carbonization process employed for each material, with the tows undergoing continuous processing and the felts following a batch process. Three-electrode half-cell EIS measurements were conducted to elucidate positive and negative electrode contributions. Activated continuous carbon filament electrodes exhibited consistent electrode activities in both the catholyte (VO2+/VO2+) and anolyte (V3+/V2+), whereas the electrochemical activity of felts was limited by the electrode deactivation in the anolyte.