Fig 3 - uploaded by Krisztina László
Content may be subject to copyright.
TEM images of a-b) the SiO 2 nanoparticles and the SiO 2 /oxide nanocomposites; c) SiO 2 /TiO 2 (80 °C), d) SiO 2 /TiO 2 (300 °C), e) SiO 2 / Al 2 O 3 (80 °C), f) SiO 2 / Al 2 O 3 (250 °C), g) SiO 2 /ZnO (80 °C), h) SiO 2 / ZnO (250 °C)
Source publication
In this work, the photocatalytic properties of amorphous and crystalline TiO2 deposited on oxide and polymer nanoparticles by atomic layer deposition (ALD) were studied. Beside TiO2, as reference, both ALD grown amorphous Al2O3 and crystalline ZnO layers were also examined. When choosing the carrier, the priority was that it had no effect on the ph...
Contexts in source publication
Context 1
... preparation of SiO 2 nanoparticles by sol-gel method and the synthesis of the PMMA particles by emulsion polymerization were successful. It can be seen in the TEM images ( Fig. 3a-b and Fig. 4a-b) that in both cases the particles were spherical; the SiO 2 nanoparticles had a diameter of 100-150 nm (Fig. 3 a-b), while the size of the PMMA particles was 50-100 nm (Fig. 4 ...
Context 2
... preparation of SiO 2 nanoparticles by sol-gel method and the synthesis of the PMMA particles by emulsion polymerization were successful. It can be seen in the TEM images ( Fig. 3a-b and Fig. 4a-b) that in both cases the particles were spherical; the SiO 2 nanoparticles had a diameter of 100-150 nm (Fig. 3 a-b), while the size of the PMMA particles was 50-100 nm (Fig. 4 ...
Context 3
... the deposition, the composites were investigated with TEM again (Fig. 3 and Fig. 4). In the case of the SiO 2 substrate (Fig. 3 c-h), it was visible that core/shell structured nanoparticles were successfully prepared, the thickness of the deposited oxide layers was about 10-20 nm in all samples. This showed that the growth-per-cycle (GPC) [34] value for these oxides vary greatly, i.e. achieving the same (Fig. 4 c) ...
Context 4
... the deposition, the composites were investigated with TEM again (Fig. 3 and Fig. 4). In the case of the SiO 2 substrate (Fig. 3 c-h), it was visible that core/shell structured nanoparticles were successfully prepared, the thickness of the deposited oxide layers was about 10-20 nm in all samples. This showed that the growth-per-cycle (GPC) [34] value for these oxides vary greatly, i.e. achieving the same (Fig. 4 c) softened during the preparation of the composites, ...
Similar publications
TiO2 and ZnO single and multilayers were deposited on hydroxyl functionalized multi-walled carbon nanotubes using atomic layer deposition. The bare carbon nanotubes and the resulting heterostructures were characterized by TG/DTA, Raman, XRD, SEM-EDX, XPS, TEM-EELS-SAED and low temperature nitrogen adsorption techniques, and their photocatalytic and...
Citations
... The deposition of the ZnO layer can be done by low temperature ALD, if needed. The coating of highly porous silica particles is also possible [133][134][135]. Synthesis of hollow nanoparticles is achievable using sacrificial nanoparticles like carbon nanospheres. ...
... The authors suggested that this effect may be related to the C incorporation during the ALD deposition. This statement was based on the increment of the C 1 s signal from the X-ray photoelectron spectroscopy (XPS), when compared with the same film produced by sputtering [59]. ALD of ZnO was also studied on PMMA in the elaboration of photocatalysts for wastewater treatment. ...
... Photocatalytic efficiency of the amorphous TiO2. After 90 min, the methylene orange dye degraded 5% under UV-A illumination [adapted from[59], this work by Orsolya Kéri is licensed under a Creative Commons Attribution (CC BY 4.0)]. ...
Poly (methyl methacrylate) (PMMA) is a thermoplastic synthetic polymer, which displays superior characteristics such as transparency, good tensile strength, and processability. Its performance can be improved by surface engineering via the use of functionalized thin film coatings, resulting in its versatility across a host of applications including, energy harvesting, dielectric layers and water purification. Modification of the PMMA surface can be achieved by atomic layer deposition (ALD), a vapor-phase, chemical deposition technique, which permits atomic-level control. However, PMMA presents a challenge for ALD due to its lack of active surface sites, necessary for gas precursor reaction, nucleation, and subsequent growth. The purpose of this review is to discuss the research related to the employment of PMMA as either a substrate, support, or masking layer over a range of ALD thin film growth techniques, namely, thermal, plasma-enhanced, and area-selective atomic layer deposition. It also highlights applications in the selected fields of flexible electronics, biomaterials, sensing, and photocatalysis, and underscores relevant characterization techniques. Further, it concludes with a prospective view of the role of ALD in PMMA processing.
... In another study, TiO 2 and Al 2 O 3 thin films were deposited on different polymeric substrates, including PMMA, to examine hardness of coated polymers by nanoscratch testing [39]. Table 1 summarizes TiO 2 ALD studies using various precursors on different types of PMMA (i.e., thick substrate, spin-coated thin films, nanoparticles, and nanofibers) [33,[35][36][37][38][40][41][42][43][44][45][46]. ...
Polymethyl methacrylate (PMMA) is a widely used polymer in applications such as engineering structural plastics, energy storage materials, and biomaterials. However, its poor surface properties lead to fracture and deformation. Functionalization of the PMMA surface can make it more resistant to aggressive environments and prevent it from biodegradation, discoloration, and increased surface roughness. Here, atomic layer deposition (ALD) was used to deposit TiO2 thin films from tetrakis(dimethylamido)titanium (TDMAT) and ozone on PMMA substrates to improve its surface properties without the need for plasma assistance or another interlayer. Spectroscopic ellipsometry was used for the first time to measure the metal oxide film thickness on thick PMMA substrates. Two different growth regimes were observed, one for initial and the other for later ALD cycles. Initially, the growth rate on PMMA was 1.39 Å/cycle, which is ~ 3.5 times higher than that on stand-alone silicon (0.4 Å/cycle); this is attributed to cyclic chemical vapor deposition of TDMAT and moisture within PMMA concomitant with TiO2 ALD from TDMAT and ozone. However, after the formation of ~ 30-nm-thick film on PMMA, the TiO2 growth rate became similar to that on silicon. Moreover, our results revealed that the presence of PMMA in the deposition reactor affects the TiO2 growth rate on silicon substrates as well. These findings are discussed and corroborated with residual gas analyzer and X-ray absorption near-edge structure data. The thermal stability of the PMMA samples was examined by thermogravimetric analysis. Chemical composition and surface roughness of coated PMMA were studied by X-ray photoelectron spectroscopy and optical profilometry, respectively. The TiO2 coating increased wettability by ~ 70% and surface hardness by 60%.
... However, both our experience and other work with amorphous titania coatings were allowed to state that these systems have potential as photocatalytically active materials [13,29,30]. Keri et al. also observed the clearly detectable photocatalytic effect of amorphous TiO 2 deposited by the atomic layer deposition method on the SiO 2 and PMMA [31]. Moreover, Kaura and Singh used the density function theory (DFT) to investigate structural and electronic properties of amorphous TiO 2 layers, which can be applied in hydrogen production using photocatalytic water splitting [32]. ...
... The results of these studies indicate that amorphous systems should be considered as potential photocatalytically active systems. It is important to have in mind that the difference in photocatalytic activity is associated with numerous different coexisting factors, such as specific surface area, pore and crystal size distribution, preparation methods, degree of surface hydroxylation, and the number of defects in the crystal structure [22,[30][31][32][33]. ...
The last twenty years have been a period of intense investigations of materials based on titanium dioxide, which have unique properties and functionalities, and which can be used in various areas of medicine. As a part of this issue, the results of our works for the assessment of the photocatalytic activity of titanium dioxide nanocoatings of different nanoarchitecture (nanoporous, nanotubular, nanosponge-like and nanofibrous examples), which were earlier checked in terms of their biocompatibility and usability for the modification of medical devices' surfaces, are presented. The studied materials were produced on the surface of Ti6Al4V substrates using electrochemical and chemical oxidation methods. The activity of produced titania materials was studied on the base of the methylene blue (MB) degradation effect, in accordance to ISO 10678:2010. In our works, we have focused on the analysis of the correlation between the photocatalytic activity of nanoarchitecturally different TiO2 coatings, their morphology and structure. The obtained results prove that all studied coatings, both amorphous and amorphous containing crystalline domains, revealed photocatalytic activity in the photoinduced degradation of the organic pollution standard. This activity may be an additional advantage of medical device coatings, being adequate for use in sterilization processes applying UVA light.
... However, these results remain better when compared to Orsolya et al. [17] which had a low catalytic effect (around 5%) by using the same type of catalyst but another type of pollutant (methyl orange). On the other hand, Benhabiles et al. [11] chose to add PVDF to the TiO 2 / PMMA mixture and they were able to achieve a degradation approaching 90%, but it should be fairly noted that they used a 500 W lamp, which is more powerful than the one we used. ...
In this work, a simple and effective approach to prepare a poly methyl methacrylate – TiO2 (TiO2/PMMA) film photocatalyst, by cheap and low coast technique was presented. The characterization of the film by XRD, FTIR and Transmittance spectroscopy; confirmed that TiO2 has been well deposited on the surface of the polymer.
The film prepared was subsequently used in photodegradation of Methylene Blue (MB) under artificial UV irradiation and showed a good prospect for the immobilization of TiO2 intended for the photodegradation of pollutants generally present in waters.
... Titanium dioxide is used in a number of applications including self-cleaning, antimicrobial thin film coatings, photocatalysis, gas sensing and dye-sensitized solar cells [1][2][3][4][5]. This has led to a lot of research in the preparation of TiO 2 nanofibers with well-controlled morphology [6][7][8][9][10]. ...
A new electrospinning process was developed for preparing TiO2 nanofibers using a water-soluble Ti-precursor, [bis(kappa1O-hydroxo)(bis(kappa2O,O′-lactato)titanium(IV)] commonly known as titanium(IV) bis (ammonium lactato) dihydroxide (TiBALDH). The importance of the study is justified by the fact that Ti-precursors used for electrospinning, sol–gel, hydrothermal and other fiber synthesis processes are mostly non-water soluble. Accordingly, anatase TiO2 nanofibers of diameter between 20 and 140 nm were synthesized by electrospinning and annealing. Polyvinylpyrrolidone (PVP) and different concentrations of TiBALDH were dissolved in a mixture of water, ethyl alcohol and acetic acid to optimize the electrospinning conditions. The thermal decomposition and fragmentation of PVP, TiBALDH and the fibers with 50% mass fraction of TiBALDH were studied by TGA-MS measurements. The fibers were then annealed at 1 °C min⁻¹ until 600 °C. The TiO2 fibers were characterized using SEM–EDX, FTIR and XRD
La photocatalyse hétérogène est une méthode très efficace comparée aux
traditionnelles techniques pour le traitement des eaux contaminées. Elle présente plusieurs
avantages dont on peut citer : - la bonne capacité à dégrader efficacement un spectre large de
contaminants organiques jusqu’à leur minéralisation totale ainsi que leurs produits de
transformation. – L’habilité à désinfecter ces eaux de microorganismes pathogènes. – Les
conditions opératoires douces (T=25°C, P=1atm). 𝑇𝑖𝑂2 et ZnO restent les photocatalyseurs les
plus utilisés et les plus documentés, grâce principalement à leur grande stabilité chimique, photostabilité, coût relativement faible, ainsi que leur faible toxicité. Le mécanisme d'utilisation de
ces semi-conducteurs directement en suspension, présente l’inconvénient du passage par une
étape de filtrage à la fin du traitement et donc le défi technique de séparer le catalyseur de la
solution, une étape supplémentaire qui peut s’avérer couteuse.
Pour y remédier, les recherches récentes penchent vers l’immobilisation des photocatalyseurs
sur divers supports comme : verre, quartz, silice, charbon actif, textile, céramique ou même
polymère. Cette immobilisation peut affecter la performance photocatalytique, la surface et
l'adsorption du semi-conducteur, mais elle présente l'avantage de gérer l'eau contaminée en flux
continu puisqu'elle élimine le besoin de séparer les particules de catalyseur une fois l'eau traitée.
Dans ce contexte, nous avons procédé à la préparation de films par immobilisation de ZnO et
𝑇𝑖𝑂2 sur le support polymère poly méthacrylate de méthyle (PMMA). Ainsi, nous avons préparé
des films photoctalytiques, nous les avons caractérisés par plusieurs techniques ; pHZPC, FTIR,
DRX et Fluorescence X, et nous avons étudié leur effet sur la dégradation de polluants
organiques (colorant : bleu de methylène et direct bleu 199) sous rayonnement UV (365nm).
Investigation qui a été suivie par spectroscopie UV-visible et a donné une efficacité ne dépassant
pas 70% avec apparition de phénomène d’adsorption/désorption.
Les résultats trouvés ont pu être améliorés en entamant une étude de plans d’expériences visant
à trouver les conditions optimales de traitement et d’étudier les effets des paramètres (pH,
concentration du colorant, et concentration de l’agent d’amorçage 𝐻2𝑂2) mis en jeu. Étude qui
a pu montrer que la concentration du colorant influe largement et que plus elle est élevée, plus
les catalyseurs deviennent moins performants. Le pH présente aussi une grande importance ; il
est toujours lié à la valeur du pHzpc du catalyseur et à la charge liée au type de polluant. Et, que
𝐻2𝑂2 ne présente d’effet que pour certaine valeur de pH ce qui montre l’interaction qui existe
entre ces deux paramètres.
Une optimisation des conditions opératoires a permis d’améliorer l’efficacité des catalyseurs
avec une dégradation atteignant 85%.
Patterning below 10 nm with conventional techniques such as Litho-etch (LE*), a subtractive self-aligned multiple patterning process, suffers from limitations due to edge placement errors, decreasing throughput, complexity, pattern collapse, photoresist non-uniformity. Bottom-up processes for fabrication of nano devices by means of Area selective deposition (ASD) are peaking up over top-down approaches to mitigate most of the above-mentioned problems. One of the ways to achieve ASD of an hardmask is by using extreme ultra-violet (EUV, λ-13.5 nm) lithography to single-step pattern self-assembled monolayers (SAM) on a photosensitive substrate (or layer) followed by atomic layer deposition (ALD). In this work, photo-catalytically active titanium oxide is considered as substrate for the deposition of organosilane SAMs of different chain length. Upon exposure to EUV, fragmentation of SAM’s molecules is observed though a mechanism involving electron/hole pair exchange from TiO2. This induces changes in the chemistry of the exposed area, allowing an ALD deposition in the SAM-cleared areas.
TiO2 nanoparticles surface-modified with silane moieties, which can be directly coated on a flexible substrate without the requirement of any binder materials and postsintering processes, are synthesized and characterized using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller, X-ray photoelectron spectroscopy, Raman spectroscopy, photoluminescence spectroscopy, time-correlated single-photon counting, and transmission electron microscopy. The viability of the prepared surface-modified TiO2 (M-TiO2) sheets as a catalyst for the photo-induced degradation of a model dye, methylene blue, was checked using UV-visible absorption spectroscopy. The data suggest that, compared to unmodified TiO2, M-TiO2 sheets facilitate better dye-degradation, which leads to a remarkable photocatalytic activity that results in more than 95% degradation of the dye in the first 10 min and more than 99% of the degradation in the first 50 min of the photocatalytic experiments. We also demonstrate that M-TiO2 can be recycled with negligible reduction in photocatalytic activity. Further, the photovoltaic properties of the developed M-TiO2 sheets were assessed using UV-visible absorption spectroscopy, electrochemical impedance spectroscopy (EIS), and photochronoamperometry. Dye-sensitized solar cells (DSSC) fabricated using M-TiO2 as the photoanode exhibited a photoconversion efficiency of 4.1% under direct sunlight. These experiments suggested that M-TiO2 sheets show enhanced photovoltaic properties compared to unmodified TiO2 sheets, and that, when N-719 dye is incorporated, the dye-TiO2 interaction is more favorable for M-TiO2 than bare TiO2. The simple solution processing method demonstrated in this paper rendered a highly flexible photoanode made of M-TiO2 with superior charge-separation efficiency to an electrode made of bare TiO2. We propose that our findings on the photovoltaic properties of M-TiO2 open up arenas of further improvement and a wide scope for the large-scale production of flexible DSSCs on plastic substrates at room temperature in a cost-effective way.
Titanium(IV) oxide (TiO2) and zirconium(IV) oxide (ZrO2) are well-known materials for their biocompatibility, hydrophilicity, antimicrobial activity, and excellent mechanical properties. Polymethyl methacrylate (PMMA), on the other hand, has many applications in medicine, biomedical systems, and engineering. However, its poor surface and mechanical properties limit its applications. The purpose of this study is how functionalization of PMMA would provide surface protection and reduce microbial adherence and biofilm formation. Hence, low-temperature Atomic Layer Deposition (ALD) was used to deposit TiO2, ZrO2, and TiO2/ZrO2 mixed oxides nanofilms on PMMA substrates. Surface composition was examined and Ti:Zr ratios were calculated through x-ray photoelectron spectroscopy. The coatings increased wettability and slightly enhanced nanohardness of PMMA. No significant change was observed in the surface roughness of PMMA after ALD. The nanocoatings protected the PMMA surface from thermal and brushing challenges by maintaining wettability, surface roughness, and film integrity. Additionally, compared to control, the mixed oxides with 1:2 cycle ratio of TiO2:ZrO2 showed a significant reduction on all bacterial and fungal initial adhesion and biofilm formation, while the TiO2 film provided reduction at initial fungal adhesion. Thus, TiO2/ZrO2 ALD on PMMA could enhance its surface, mechanical, and biological properties, preparing it for biomedical and engineering applications.
