Deposition Of Nanoparticles Research Articles

Improved PMS activation by natural sepiolite/Fe3O4 composite for effective tetracycline degradation: Performance, mechanism and degradation pathway

In this study, Fe3O4/sepiolite composites as peroxymonosulfate (PMS) catalysts were successfully synthesized via a simple water bath method for tetracycline (TC) degradation. The results indicated that the composite with 70% Fe3O4 loading amount exhibited the highest TC degradation efficiency (90.12%), and its reaction rate constant (0.02193 min−1) was around 2.07 times higher than that of pure Fe3O4. The enhanced catalytic activity was mainly attributed to the uniform deposition of Fe3O4 nanoparticles with smaller grain size (17.24 nm) on sepiolite, leading to the larger specific surface area (120.61 m2/g) and more exposed reaction active sites. The electron paramagnetic resonance (EPR) and quenching experiments displayed that 1O2 species played the predominant roles in TC degradation process. Besides, potential catalytic mechanisms and degradation pathways of TC were proposed. The toxicity of TC was reduced during the degradation process. Overall, this work can provide a new strategy for the rational design of promising mineral-based PMS catalyst for the wastewater treatment.

Understanding dynamic voltammetry in a dissolving microdroplet.

Droplet evaporation and dissolution phenomena are pervasive in both natural and artificial systems, playing crucial roles in various applications. Understanding the intricate processes involved in the evaporation and dissolution of sessile droplets is of paramount importance for applications such as inkjet printing, surface coating, and nanoparticle deposition, etc. In this study, we present a demonstration of electrochemical investigation of the dissolution behaviour in sub-nL droplets down to sub-pL volume. Droplets on an electrode have been studied for decades in the field of electrochemistry to understand the phase transfer of ions at the oil-water interface, accelerated reaction rates in microdroplets, etc. However, the impact of microdroplet dissolution on the redox activity of confined molecules within the droplet has not been explored previously. As a proof-of-principle, we examine the dissolution kinetics of 1,2-dichloroethane droplets (DCE) spiked with 155 μM decamethylferrocene within an aqueous phase on an ultramicroelectrode (r = 6.3 μm). The aqueous phase serves as an infinite sink, enabling the dissolution of DCE droplets while also facilitating convenient electrical contact with the reference/counter electrode (Ag/AgCl 1 M KCl). Through comprehensive voltammetric analysis, we unravel the impact of droplet dissolution on electrochemical response as the droplet reaches minuscule volumes. We validate our experimental findings by finite element modelling, which shows deviations from the experimental results as the droplet accesses negligible volumes, suggesting the presence of complex dissolution modes.

Electrochemical deposition of gold nanoparticles on carbon ultramicroelectrode arrays.

Electrode surfaces functionalized with gold nanoparticles (AuNP) are widely used in electroanalysis, electrocatalysis, and electrochemical biosensing due to their increased surface area and conductivity. Electrochemical deposition of AuNPs offers advantages over chemical synthesis, including better control over AuNP size, dispersion, and morphology. This study examines the electrodeposition of AuNPs on carbon ultramicroelectrode arrays (CUAs) focusing on electrodeposition parameters, such as deposition potential, deposition time, and gold ion concentration. Detailed analysis based on scanning electron microscopy revealed that higher reductive potentials and shorter deposition times result in smaller AuNP particle sizes and greater particle counts. Unlike previous studies using planar, macro-sized electrodes and millimolar concentrations of gold ion, as well as longer deposition times (e.g., 100-300 s), this research employed micromolar concentration ranges (25-50 μM) of gold ion solution and shorter deposition times (5-60 s) for successful electrodeposition of AuNPs on the array-based CUAs. This is attributed to the physical properties of the ultramicroelectrodes in the array geometry and the distinct material composition of the CUAs. The gold amounts deposited on the CUA electrodes were determined (88.73 ± 0.06 nmol cm-2), which were in correlation with the electrocatalytic responses for the hydrogen evolution reaction (HER) measured on AuNP-modified CUAs. Overall, the array-based geometry, nanometer-scale electrode sizes, and unique material composition of the CUAs significantly influence AuNP electrodeposition. This study underscores the importance of systematically characterizing the electrodeposition parameters on novel electrode surfaces.

Integration of a recyclable silver substrate for in situ surface-enhanced Raman spectroscopy in digital microfluidics.

We report a new chip-integrated recyclable SERS substrate, achieved by photochemical deposition of silver nanoparticles onto titanium dioxide (TiO2) thin film. Facilitated by the photocatalytic activity of titanium dioxide the SERS substrate can be recycled for multiple analysis. This enables quasi-real time detection of various compounds in an automated and reusable DMF-SERS platform.

Atomic layer deposition of Pt nanoparticles using dimethyl (N, N–dimethyl-3-butene-1-amine−N) platinum and H2 reactant and its application to 2D WS2 photodetectors

2D transition metal dichalcogenides (2D TMDCs) have thin and flexible structures and can be widely applied to nanoelectronics technology as a representative of 2D materials. Research studies on the surface functionalization of 2D TMDCs with nanoparticles have been actively conducted for fabrication of high-performance devices. Specifically, platinum (Pt) has attracted significant attention as a surface functionalization material in various applications, including photosensors, biosensors, and gas sensors due to its effective catalytic effect and excellent corrosion resistance. However, solution-based methods and PVD technologies, widely used for Pt nanoparticle synthesis, have difficulties forming fine particles dispersed on nanomaterials. Atomic layer deposition (ALD) is emerging as an advantageous method for forming nanoparticles, and dimethyl (N,N-dimethyl-3-buten-1-amine-N) platinum (DDAP) can overcome disadvantages of conventional ALD Pt precursors. In this study, we successfully synthesized Pt films using hydrogen as a new reactant in the DDAP-based ALD Pt process and evaluated formation of nanoparticles on SiO2/Si substrates. Subsequently, the ALD Pt-functionalized photodetector was fabricated with 2D WS2, a representative visible-light photodetector material, and improvement of photocurrent was confirmed by providing additional carriers via the localized surface plasmon resonance phenomenon. Furthermore, preferentially growing at high surface energy points, such as defects on WS2 nanosheets, can suppress the capture of photoexcited electrons by defects, consequently extending the carrier lifetime and preventing surface oxidation of the device. In the wavelength range of 500–1200 nm, the photoresponsivity of the ALD Pt-functionalized WS2 photodetector was improved more than 10–20 times compared to pristine WS2, and the response time was also noticeably improved. This study presents a novel approach to Pt functionalization using ALD, opening new possibilities for advanced nanodevice applications.

Eco-friendly preparation and characterization of high-performance electrothermal graphene-AgNPs/lignocellulose composites.

Graphene-based (Gr-based) electrothermal heaters, due to their light weight, low electrical resistance, high thermal conductivity, and easy accessibility, have attracted widespread attention in the field of electrothermal heating. To achieve a high steady-state temperature in electrothermal heaters under low voltage, here we constructed a Gr-based film with low electrical resistance. Firstly, we employed non-toxic vitamin C to reduce silver nitrate for the in situ chemical deposition of silver nanoparticles (AgNPs) on the Gr surface. The SEM results confirmed that the AgNPs were uniformly deposited on the Gr surface. The synergistic interaction between AgNPs and Gr provided high-speed electrons transport paths for the film. On the other hand, we employed biodegradable lignocellulose fiber (LCF) as a dispersant and film-forming agent. The aromatic ring structure of LCF interacts with Gr via π-π interactions, aiding the dispersion of Gr in aqueous solutions. SEM results revealed that LCF permeated through the surfaces and interstices of the two-dimensional Gr sheets, providing mechanical support for the composite film. This approach enables the creation of freestanding Gr-AgNPs/LCF electrothermal composites. The resistivity and electrothermal results demonstrated that the obtained 20 wt% Gr-based composite film possessed low electrical resistance (5.4 Ω sq-1) and exhibited an outstanding saturated temperature of 214 °C under a very low input voltage of 7 V. The preparation method of this Gr-based composite film is simple, easy to operate, and environmentally friendly, providing a new reference for the preparation of eco-friendly and high-performance resistance heating electronics.

Dispersed MnO2 nanoparticles/sugarcane bagasse-derived carbon composite as an anode material for lithium-ion batteries.

Bagasse-derived carbon electrodes were developed by doping with nitrogen functional groups and compositing with high-capacity MnO2 nanoparticles (MnO2/NBGC). The bagasse-derived biochar was N-doped by refluxing in urea, followed by the deposition of MnO2 nanoparticles onto its porous surface via the hydrothermal reduction of KMnO4. Different initial KMnO4 loading concentrations (i.e. 5, 10, 40, and 100 mM) were applied to optimize the composite morphology and the corresponding electrochemical performance. Material characterization confirmed that the carbon composite has a mesoporous structure along with the dispersion of MnO2 nano-particles on the N-containing carbon surface. It was found that the 5-MnO2/NBGC sample exhibited the highest electrochemical performance with a reversible capacity of 760 mA h g-1 at a current density of 186 mA g-1. It delivered reversible capacities of 488 and 390 mA h g-1 in cycle tests at 372 and 744 mA g-1, respectively, for 150 cycles and presented good reversibility with nearly 100% coulombic efficiency. In addition, it could exert high capacities up to 388 and 301 mA h g-1 even under high current densities of 1860 and 3720 mA g-1, respectively. Moreover, most of the prepared composite products showed high rate capability with great reversibility up to more than 90% after testing at a high current density of 3720 mA g-1. The great electrochemical performance of the MnO2/NBGC nanocomposite electrode can be attributed to the synergistic impact of the hierarchical architecture of the MnO2 nanocrystals deposited on porous carbon and the capacitive effect of the N-containing defects within the carbon material. The nanostructure of the MnO2 particles deposited on porous carbon limits its large volume change during cycling and promotes good adhesion of MnO2 nanoparticles with the substrate. Meanwhile, the capacitive effect of the exposed N-functional groups enables fast ionic conduction and reduces interfacial resistance at the electrode interface.

Fabrication of Ag-perovskite substrates for surface-enhanced Raman scattering via all-vacuum deposition

The first all-vacuum deposition for fabricating perovskite-based substrates for surface-enhanced Raman scattering (SERS) is reported. While thermal deposition of silver nanoparticles is commonly employed to generate Ag substrates for SERS...

Atomic layer deposition of Pd nanoparticles and single atoms on self-supported carbon monolithic catalysts synergistically boosts the hydrogen evolution reaction

Pd nanoparticles and Pd single atoms were anchored on carbonized wood. Pd NPs facilitated the decomposition of water while the Pd SAs promoted the adsorption of H.

Bismuth-oxide nanoparticles: study in a beam and as deposited.

Bi2O3 is a promising material for solid-oxide fuel cells (SOFC) due to the high ionic conductivity of some phases. The largest value is reached for its δ-phase, but it is normally stable at temperatures too high for SOFC operation, while nanostructured oxide is believed to have more suitable stabilization temperature. However, to manufacture such a material with a controlled chemical composition is a challenging task. In this work, we investigated the fabrication of nanostructured Bi2O3 films formed by deposition of free Bi-oxide nanoparticles created in situ. The particle-production method was based on reactive sputtering and vapour aggregation. Depending on the fabrication conditions, the nanoparticles contained either a combination of Bi-metal and Bi-oxide, or only Bi-oxide. Prior to deposition, the free particles were probed in the beam - by synchrotron-based photoelectron spectroscopy (PES), which allowed assessing their composition "on the-fly". The nanoparticle films obtained after deposition were studied by PES, scanning electron microscopy, transmission electron microscopy, and electron diffraction. The films' chemical composition, grain dimensions, and crystal structure were probed. Our analysis suggests that our method produced Bi-oxide films in more than one polymorph of Bi2O3.

Au nanoparticles decorated β-Bi2O3 as highly-sensitive SERS substrate for detection of methylene blue and methyl orange.

In this work, Au/Bi2O3 was synthesized by loading Au nanoparticles (NPs) onto β-Bi2O3 by a simple solution reduction method. β-Bi2O3 was synthesized by a precipitation-thermal decomposition procedure, which results in significantly improved SERS detection limits down to 10-9 M for methylene blue (MB) and 10-7 M for methyl orange (MO) as probe molecules, comparable to those reported for the best semiconductor SERS substrates. In particular, further deposition of Au NPs (5.20% wt%) onto β-Bi2O3 results in a two-order-of-magnitude enhancement in detection sensitivity, achieving a detection limit of 10-11 M for MB and 10-9 M for MO. Under ultraviolet/visible irradiation, the Au/Bi2O3 hybrids substrate exhibits superior self-cleaning ability due to its photocatalytic degradation ability which can be applied repeatedly to the detection of pollutants. The advanced composite substrate simultaneously achieved ultra-low mass loading of Au NPs, outstanding detection performance, good reproducibility, high stability and self-cleaning ability. The development strategy of low load noble metal coupled high performance semiconductor β-Bi2O3 to obtain nano-hybrid materials provides a method to balance SERS sensitivity, cost effectiveness and operational stability, and can be synthesized in large quantities, which is a key step towards commercialization and has good reliability prospects.

Исследование интенсификации теплообмена при кипении наножидкости на поверхности нагрева с нанорельефом

The study of the boiling liquids processes is currently relevant, as it affects many energy areas and can offer new ways to improve the efficiency of energy plants. The properties and the nanolayer formation processes on the heater surface are the area of interest. Modification of the heater surface in power machinery with the formation of a porous layer on them is more promising than using nanofluid as a heat transfer fluid. The research of the nanolayer formation a during boiling provides insights into its properties and its effect on heat transfer during boiling. It has been experimentally established that when the suspension boils, porous deposits form on the heat exchange surface. Initially, the roughness caused by the deposition of nanoparticles increases, but after a while it begins to decrease due to the alignment of the sediment profile.

A plasma-3D print combined in vitro platform with implications for reliable materiobiological screening.

Materiobiology is an emerging field focused on the physiochemical properties of biomaterials concerning biological outcomes which includes but is not limited to the biological responses and bioactivity of surface-modified biomaterials. Herein, we report a novel in vitro characterization platform for characterizing nanoparticle surface-modified 3D printed PLA scaffolds. We have introduced innovative design parameters that were practical for ubiquitous in vitro assays like those utilizing 96 and 24-well plates. Subsequently, gold and silica nanoparticles were deposited using two low-temperature plasma-assisted processes namely plasma electroless reduction (PER) and dusty plasma on 3D scaffolds. Materiobiological testing began with nanoparticle surface modification optimization on 96 well plate design 3D scaffolds. We have employed 3D laser confocal imaging and scanning electron microscopy to study the deposition of nanoparticles. It was found that the formation and distribution of the nanoparticles were time-dependent. In vitro assays were performed utilizing an osteosarcoma (MG-63) cell as a model. These cells were grown on both 96 and 24 well plate design 3D scaffolds. Subsequently, we performed different in vitro assays such as cell viability, and fluorescence staining of cytoskeletal actin and DNA incorporation. The actin cytoskeleton staining showed more homogeneity in the cell monolayer growing on the gold nanoparticle-modified 3D scaffolds than the control 3D PLA scaffold. Furthermore, the mineralization and protein adsorption experiments conducted on 96 well plate design scaffolds have shown enhanced mineralization and bovine serum albumin adsorption for the gold nanoparticle-modified scaffolds compared to the control scaffolds. Taken together, this study reports the efficacy of this new in vitro platform in conducting more reliable and efficient materiobiology studies. It is also worth mentioning that this platform has significant futuristic potential for developing as a high throughput screening platform. Such platforms could have a significant impact on the systematic study of biocompatibility and bioactive mechanisms of nanoparticle-modified 3D-printed scaffolds for tissue engineering. It would also provide unique ways to investigate mechanisms of biological responses and subsequent bioactive mechanisms for implantable biomaterials. Moreover, this platform can derive more consistent and reliable in vitro results which can improve the success rate of further in vivo experiments.

Nanoparticle assembly by transient topography induced by applying soft lithography to block copolymer films.

We present a simple approach for patterning metal nanoparticles into periodic superstructures on flat films spanning centimeter-square areas. Our approach is based on capillary force lithography, a soft lithography method that is used to impart topography to molten polymer films, and applies it to block copolymer films to obtain substrates featuring both topographic and chemical contrasts that can serve as templates for the selective deposition of nanoparticles. Here we show that flattening the films by exposure to solvent vapour prior to nanoparticle deposition not only retains chemical heterogeneity but also provides access to unique hierarchically-organized nanoparticle superstructures that are unattainable by other methods. Such structures could be useful for optical, sensor, and catalytic applications.

Palladium nanoparticle deposition on spherical carbon supports for heterogeneous catalysis in continuous flow

Pd/C spherical bead catalysts were synthesised and evaluated in small-scale screenings via a recirculating batch platform (20 mg). The applicability of the catalysts was subsequently demonstrated over a two-day operating period on a larger scale.

Multilayer coatings based on gold nanoparticles and polymers with bovine serum albumin as a functional layer for the chiral separation in capillary electrochromatography.

In this study, we developed physically adsorbed multi-layer coatings using poly-l-lysine or poly(diallyldimethylammonium chloride) and gold nanoparticles, which were functionalized with bovine serum albumin for the chiral separation in electrochromatography. The approach involves sequentially depositing positively charged polymers and negatively charged citrate-stabilized gold nanoparticles. By repeating this modification cycle, we created two- and four-layer coatings, which were sequentially functionalized with albumin forming three- and five-layer coatings that were finally applied for the separation of enantiomers of dl-tryptophan. The formed coatings exhibit stability across a pH range of 2-10 and feature a dense, uniform surface, as confirmed by scanning electron microscope images. The number of layers impacted nanoparticle deposition density, with five-layer coatings being denser than three-layer ones. Five-layer coatings enable baseline separation of dl-tryptophan enantiomers, whereas three-layer coatings require the presence of albumin in the background electrolyte for separation. Therefore, increasing the number of layers and gold nanoparticles density enhances albumin active center concentration on capillary walls, improving the separation of dl-tryptophan enantiomers. The five-layer coatings can be easily fabricated and possess good repeatability of analytes migration time.

Construction of durable antibacterial cellulose textiles through grafting dynamic disulfide-containing amino-compound and nanosilver deposition

Cotton textile is very comfortable to wear, and also provides an ideal environment for bacterial propagation, easily causing harm to human health. In order to address this issue, various antibacterial techniques are employed for cotton finishing. However, some processes are complex and involve the use of environmentally unfriendly chemicals. In this work, a durable and efficient antibacterial cotton fabric was prepared via grafting of an amino-compound containing dynamic disulfide bonds, and then in-situ deposition of silver nanoparticles (AgNPs). Briefly, the reactive α-lipoic acid-modified polyethyleneimine (mPEI) was introduced to the cotton fibers via thiol-ene click reaction. Subsequently, the amino groups and dynamically-generated sulfhydryl groups in the mPEI molecules were used to initiate the ultrafast reduction of silver ions without the participation of additional reductant, constructing a stable antibacterial layer on fiber surface. The results reveal that the amino and thiol groups of mPEI could form coordination bonds with the deposited silver nanoparticles, and the antibacterial ability of AgNP@cotton-g-mPEI fabric remains at a high level even after 20 washing cycles. After 30 min of contact with Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), the antibacterial rates against both bacteria reached 99.99 %. Meanwhile, the network matrix constructed by the recombination of the dynamic disulfide bonds in mPEI endows the cotton fabric with detectable wrinkle resistance and encouraging anti-ultraviolet effect. The present work provides a novel alternative for preparation of durable and efficient antibacterial textiles.

Spark deposition of lanthanum-carbon composite nanoparticles embedded in a polypropylene membrane for phosphate removal in aqueous solutions

Eutrophication in water, such as rivers or lakes, is becoming increasingly serious. Controlling the phosphate concentration in such waters is the key to solving the eutrophication problem. The use of adsorption methods to limit the level of phosphate in aqueous solutions has the advantages of cost-effectiveness, ease of operation, and selectivity. In this study, a modified polypropylene (PP) membrane was used as the platform for the in-situ deposition of lanthanum-carbon (La-C) composite nanoparticles. Uniform lanthanum (La) and carbon (C) aerosols were deposited on the PP film using spark ablation, and the combined hydrothermal method was used to synthesise the nano-confinement crystal PP-La-C (PLC) for phosphorus removal in an aquatic environment. Because of the nanoconfinement of the PLC, particle agglomeration deactivation was effectively solved, and the doping of C changed the shape of La(OH)3 from particles to ultrafine nano-fibres, which resulted in a larger surface area and more abundant active sites, and the overall adsorption performance was improved. The addition of C reduced the cost, and La proved to be the main active site for phosphate capture. The adsorption test revealed a significant adsorption capability of 194.1 mg⋅P⋅g−1. Three variables, such as reaction time, dose, and original phosphate concentration, were selected and a model for predicting lake water phosphate removal efficiency was developed using the central composite design method. When PLC was used to treat water samples from Lake Qilu (Yunnan, China), the observed removal rate of total phosphorus was 94 %, which is consistent with the model prediction. A series of characterisations established that ligand exchange and multilayer adsorption were the main mechanisms of phosphorus removal.

Flexible multiscale cavity with omnidirectionality and high stability for in-site SERS detection of nanoplastics on oyster

Nanoplastics are widespread and pose a potential threat to human health. In this work, we designed a flexible multiscale cavity structured (MCS) surface-enhanced Raman scattering (SERS) substrate decorating Ni3S2 nanocavity on a modified polyvinylidene fluoride (PVDF) microcavity. The dense two-dimensional Ni3S2 nanosheets can provide a large surface area for the deposition of plasmonic silver nanoparticles (Ag NPs), increasing the density and strength of the “hotspots”. Additionally, the nanocavity (width ∼500 nm), formed by the nanosheet surroundings, offers not only electromagnetic enhancement of the cavity mode for SERS but also a crucial detection site for nanoplastics attachment. This effectively addresses the challenge of SERS detection due to the scale mismatch between nanoplastics (>50 nm) and conventional “hotspots” (<10 nm). Moreover, the flexible imprinted PVDF microcavity endows the proposed substrate with omnidirectional “hotspots” enhancement, ensuring the signal stability and the feasibility of in-site detection of the actual sample. As a result, we achieved the successful in-site detection of polystyrene (PS) spheres of different sizes on the surface of oysters, with a detection limit of 10-3 mg/mL for 50 nm diameter. The flexible multiscale cavity SERS substrate is expected to show great potential in food safety and environmental monitoring.

Photodeposition synthesis of hollow g-C3N4/Ag nanotubes with high oxidation properties to enhance visible-light photocatalytic performance

A hollow Ag-deposited g-C3N4 nanotube (CNNT/Ag) with high oxidation properties was synthesized using a simple photodeposition method. The g-C3N4 nanotubes provided abundant active sites and a large specific surface area for effective deposition of Ag nanoparticles. The Ag NPs expanded the light absorption range of g-C3N4 through surface plasmon resonance (SPR) effects and acted as an electron acceptor, effectively inhibiting the recombination of photogenerated carriers, thereby improving the charge separation efficiency. The CNNT/Ag composites exhibited excellent photocatalytic performance in the visible light degradation of rhodamine B and tetracycline, 6.42 and 2.16 times higher than pure g-C3N4, respectively. The increased photocatalytic activity of CNNT/Ag composites was attributed to the synergistic electron transfer interface between CNNT and Ag NPs, promoting the migration efficiency of photo-generated carriers. This work presented a promising strategy for constructing effective photocatalysts for degrading organic pollutants using morphology optimization and SPR effects on noble metal surfaces.