Immobilization Of Nanoparticles Research Articles

Immobilization of Metal Nanoparticles to an Ultrathin Two-Dimensional Conjugated Metal-Organic Framework for Synergistic Electrocatalysis.

Metal-organic frameworks (MOFs) have been considered as promising hosts for immobilizing ultrafine metal nanoparticles (MNPs) due to their high surface area and porosity. However, electrochemical applications of such emerging composites are severely limited by the poor electrical conductivity and large size of the MOFs. Herein, we report the general synthesis of incorporating various MNPs into a conjugated MOF ultrathin nanosheet (Cu-TCPP UNS) matrix, which not only prevents agglomeration and restricts the growth of MNPs but also benefits the exposure of active sites and the transport of electrons. Specifically, the obtained PtCu@Cu-TCPP UNSs exhibited nearly two times higher mass activity for the methanol oxidation reaction (MOR) than the commercial Pt/C catalyst. Mechanistic studies reveal that the strong interaction between MNPs and Cu-TCPP promotes the oxidation of the CO intermediate. Moreover, the PtCu@Cu-TCPP UNSs can be employed as bifunctional electrocatalysts to couple MOR with the hydrogen evolution reaction for highly efficient hydrogen production.

Heterogenization of Palladium Trimer and Nanoparticles through Polymerization Boosted Catalytic Efficiencies in Recyclable Coupling and Reduction Reactions.

The development of heterogeneous palladium catalysts has shown continuous vitality in the field of catalysis and materials. In this work, we report one concise free radicalpolymerization approach to accomplish the aromatic palladium trimer functionalized polymers PSSy-[Pd3]+(2) and itsderived palladium nanoparticles (3). Full characterizationscould confirmthe successful combination of cationic [Pd3]+or nanoparticles with poly(p-sulfonated styrene) skeleton. Compared to their monomeric tri-palladium precursor (1) and commonPd(dba)2, Pd(PPh3)4, Pd(OAc)2, heterogeneous PSSy-[Pd3]+(2) showsmuch superior catalytic activities (0.15 mol%, TOF = 1333.3h-1) in the SMCC reaction. The identically ligated PdNPs (3)are formed in-suitin the presence of NaBH4andaccomplish quantitative reduction of4-nitrophenol in just 320s(0.50 mol%, TOF = 2250 h-1).Moreover, these heterogeneous catalysts arereused for 5-6times without significant loss of catalytic activity. Their superior catalytic ability isprobably attributed to the synergistic effect of polymer entanglement and the tri-palladium fragment.This work enlightensthat the immobilization of palladiumclustersor nanoparticles by polymerization could offer multiple advantages in stability, efficiencyand recyclabilityfortheir involvedcatalyses and show far-reaching future implications.

Green in-situ immobilization of ZnO nanoparticles for functionalization of polyester fabrics

Green in-situ immobilization of ZnO nanoparticles for functionalization of polyester fabrics

Polydopamine modification on dendritic porous silica surface for efficient adhesion of functional nanoparticles

The uniform and high-density immobilization of functional nanoparticles (NPs) on porous carriers is crucial to enhance various physicochemical properties and performances in diverse applications. However, there is a limited control towards the size and distribution of functional nanoparticles loaded on the carriers. In this work, the dendritic porous silica nanoparticles (DPSNs) featuring a three-dimensional center-radial porous structure were utilized as a nanocarrier, coated with a thin layer of polydopamine (PDA) to form DPSNs@PDA. The modified PDA exhibits strong adhesion and photothermal conversion properties. The pre-synthesized gold or platinum NPs (Au or Pt NPs) with tunable sizes were uniformly and densely loaded on the DPSNs@PDA, taking advantage of the strong adhesion properties of PDA. The resulting functional NPs-loaded DPSNs@PDA composites demonstrated excellent catalytic activity and recycling stability in heterogeneous catalysis, achieving over 95 % catalytic conversion efficiency of methylene blue (MB) after six cycles. Furthermore, due to the excellent photothermal effects of PDA and Au NPs, the apparent reaction rate increased by nearly threefold under 808 nm near-infrared (NIR) laser irradiation. The developed strategy of loading pre-synthesized NPs with tunable sizes by strong PDA adhesion force shows great potential for achieving efficient integration of various functional NPs, thereby facilitating the construction of advanced multifunctional materials.

Plasma‐electrified synthesis of atom‐efficient electrocatalysts for sustainable water catalysis and beyond

The downsizing of metal structures to the nano and atomic level, thereby creating nanoparticle catalysts (NPCs), sub‐nanometer cluster catalysts (SNCCs) or single atom catalysts (SACs), has gained significant interest. In particular, synthesizing these types of catalysts using low temperature plasma electrified methods is an emerging field which is highly applicable to electrochemical water splitting for the sustainable production of green hydrogen. Surface modification via plasma treatment provides a route for nanoparticle immobilization or single atom trapping which ensures high atom utilization during electrolysis reactions. Plasma can also be used to create NPCs, SNCCs and SACs from various precursors as well as modify their surface properties once formed which impacts significantly on the oxygen evolution reaction and hydrogen evolution reaction. Therefore, in this review we emphasize the role that low temperature plasma electrified synthetic strategies play in electrocatalyst development for water splitting reactions and explore the crucial relationship between the electronic and coordination environment of atom efficient catalysts and their resulting catalytic activity. We also discuss methods to characterize these types of catalysts and the possibility for scaling up this technology which will be required for commercial applications.

Integrating Cu2O Colloidal Mie Resonators in Structurally Colored Butterfly Wings for Bio-Nanohybrid Photonic Applications.

Colloidal Cu2O nanoparticles can exhibit both photocatalytic activity under visible light illumination and resonant Mie scattering, but, for their practical application, they have to be immobilized on a substrate. Butterfly wings, with complex hierarchical photonic nanoarchitectures, constitute a promising substrate for the immobilization of nanoparticles and for the tuning of their optical properties. The native wax layer covering the wing scales of Polyommatus icarus butterflies was removed by simple ethanol pretreatment prior to the deposition of Cu2O nanoparticles, which allowed reproducible deposition on the dorsal blue wing scale nanoarchitectures via drop casting. The samples were investigated by optical and electron microscopy, attenuated total reflectance infrared spectroscopy, UV-visible spectrophotometry, microspectrophotometry, and hyperspectral spectrophotometry. It was found that the Cu2O nanoparticles integrated well into the photonic nanoarchitecture of the P. icarus wing scales, they exhibited Mie resonance on the glass slides, and the spectral signature of this resonance was absent on Si(100). A novel bio-nanohybrid photonic nanoarchitecture was produced in which the spectral properties of the butterfly wings were tuned by the Cu2O nanoparticles and their backscattering due to the Mie resonance was suppressed despite the low refractive index of the chitinous substrate.

Electrocatalytic methanol oxidation by Au nanoparticles decorated nickel tungstate/oxide nanocomplexes

The methanol oxidation reaction (MOR) serves as a critical determinant of the energy conversion efficiency within direct methanol fuel cells (DMFC). Consequently, the development of cost-effective and efficient electrocatalysts is paramount for enhancing energy conversion efficiency associated with MOR. The nanomaterials with diverse metal atomic molar ratio of (Ni:W) were synthesized via hydrothermal method for the immobilization of Au nanoparticles (Au NPs) onto the sample surface. The crystal structure of nanocomposites was confirmed through X-ray diffraction (XRD), and transmission electron microscopy (TEM) images depicted a specific surface topography. The catalytic performance of the synthesized catalysts in the MOR was assessed through electrochemical analysis. Notably, catalyst with the Ni:W atomic ratio of 2:1, displayed superior electrocatalytic performance when compared to catalysts possessing other different metal ratios. Moreover, chronoamperometry tests conducted over 7200 s and Tafel slope analysis demonstrated the enduring activity and strong resistance to toxicity of the synthesized catalysts. These results highlight the potential of nickel-tungstate bimetallic oxide as an exceptionally efficient catalyst in the field of electrocatalysis.

Extracellular production of azurin by reusable magnetic Fe3O4 nanoparticle-immobilized Pseudomonas aeruginosa

Azurin, found in the periplasm of Pseudomonas aeruginosa, has garnered significant attention as a potential anticancer agent in recent years. High-level secretion of proteins into the culture medium, offers a significant advantage over periplasmic or cytoplasmic expression. In this study, for the first time, P. aeruginosa cells were immobilized with magnetic nanoparticles (MNPs) to ensure effective, simple and quick separation of the cells and secretion of periplasmic azurin protein to the culture medium. For this purpose, polyethyleneimine-coated iron oxide (Fe3O4@PEI) MNPs were synthesized and MNPs containing Fe up to 600 ppm were found to be non-toxic to the bacteria. The highest extracellular azurin level was observed in LB medium compared to peptone water. The cells immobilized with 400 ppm Fe-containing MNPs secreted the highest protein. Lastly, the immobilized cells were found suitable for azurin secretion until the sixth use. Thus, the magnetic nanoparticle immobilization method facilitated the release of azurin as well as the simple and rapid separation of cells. This approach, by facilitating protein purification and enabling the reuse of immobilized cells, offers a cost-effective means of protein production, reducing waste cell formation, and thus presents an advantageous method.

Colloidal Templating in Catalyst Design for Thermocatalysis.

Conventional catalyst preparative methods commonly entail the impregnation, precipitation, and/or immobilization of nanoparticles on their supports. While convenient, such methods do not readily afford the ability to control collective ensemble-like nanoparticle properties, such as nanoparticle proximity, placement, and compartmentalization. In this Perspective, we illustrate how incorporating colloidal templating into catalyst design for thermocatalysis confers synthetic advantages to facilitate new catalytic investigations and augment catalytic performance, focusing on three colloid-templated catalyst structures: 3D macroporous structures, hierarchical macro-mesoporous structures, and discrete hollow nanoreactors. We outline how colloidal templating decouples the nanoparticle and support formation steps to devise modular catalyst platforms that can be flexibly tuned at different length scales. Of particular interest is the raspberry colloid templating (RCT) method which confers high thermomechanical stability by partially embedding nanoparticles within its support, while retaining high levels of reactant accessibility. We illustrate how the high modularity of the RCT approach allows one to independently control collective nanoparticle properties, such as nanoparticle proximity and localization, without concomitant changes to other catalytic descriptors that would otherwise confound analyses of their catalytic performance. We next discuss how colloidal templating can be employed to achieve spatially disparate active site functionalization while directing reactant transport within the catalyst structure to enhance selectivity in multistep catalytic cascades. Throughout this Perspective, we highlight developments in advanced characterization that interrogate transport phenomena and/or derive new insights into these catalyst structures. Finally, we offer our outlook on the future roles, applications, and challenges of colloidal templating in catalyst design for thermocatalysis.

Immobilization of Ni nanoparticles on pyridine-functionalized MWCNTs for indirect synthesis of benzimidazoles and quinazolinones, and their molecular docking studies as effective inhibitors of α-glucosidase

Herein we report a sustainable and efficient synthesis of a few chosen five- and six-membered fused nitrogen heterocycles such as benzimidazole, and quinazolinone catalyzed by immobilization Ni NPs on pyridine-functionalized multi-walled carbon nanotubes (MWCNTs). This novel heterogeneous nanostructure catalyzed acceptorless dehydrogenative coupling of alcohols with 1,2-phenylenediamine and condensation of alcohols with 2-aminobenzamide, respectively in the synthesis of 2-substituted benzimidazoles and 2-substituted quinazolinones, with high activity, selectivity, and reusability. Furthermore, the resultant heterogeneous nanocatalyst showed the efficient catalytic synthesis of 1,2-disubstituted benzimidazoles from a hydrogen borrowing approach, involving low-cost alcohols as hydrogen donors and o-nitroaniline as hydrogen acceptors. To further study, the theoretical inhibitory activity of the newly synthesized compounds against α-glucosidase was studied by molecular docking. In silico results showed that among all the studied compounds, the 8d and 8g derivatives are the best candidates as effective inhibitors of α-glucosidase.

Flexible Scaffold Modulation of Spatial Structure and Function of Hierarchically Porous Nanoparticle@ZIF-8 Composites to Enhance Field Deployable Disease Diagnostics.

Catalytic nanoparticle@metal-organic framework (MOF) composites have attracted significant interest in point-of-care testing (POCT) owing to their prominent catalytic activity. However, the trade-off between high loading efficiency and high catalytic activity remains challenging because high concentrations of nanoparticles tend to cause the misjoining and collapse of the MOFs. Herein, a facile strategy is reported to encapsulate high concentrations of platinum (Pt) nanoparticles into zeolitic imidazolate framework-8 (ZIF-8) using polydopamine (PDA) as a support for Pt@ZIF-8 and as a flexible scaffold for further immobilization of Pt nanoparticles. The resulting composite (Pt@ZIF-8@PDA@Pt) exhibits ultrahigh Pt nanoparticle loading efficiency, exceptional catalytic activity, stability, and a bright colorimetric signal. Following integration with lateral flow immunoassay (LFIA), the detection limits for pre- and post-catalysis detection of B-type natriuretic peptide (NT-proBNP) are 0.18 and 0.015ng mL-1, respectively, representing a 6-fold and 70-fold improvement compared to gold nanoparticle-based LFIA. Moreover, Pt@ZIF-8@PDA@Pt-based LFIA achieves 100% diagnostic sensitivity for NT-proBNP in a cohort of 184 clinical samples.

Phytochemical assisted engineering of silver nanoparticles on hexagonal boron nitride: An efficient nanocatalyst for amidation and reduction reactions in aqueous medium

Of the various intermediates studied in organic chemistry, the versatility of amides has been widely seen in pharmaceuticals. However, sustainable and simple hydration of nitriles to selectively yield amides is challenging. Thus, in our efforts to explore green methodologies in synthesizing amides, we developed a new and efficient nanocatalyst: biogenically synthesized silver nanoparticles supported on phytochemicals functionalized hexagonal boron nitride (h-BNCLE@AgNPs). The characterization of the h-BNCLE@AgNPs nanocatalyst confirmed the successful formation and immobilization of the silver nanoparticles on the support, which was surveyed for the amidation of nitriles in a base-free aqueous medium by selective hydrolysis. The aryl amides were obtained in good to excellent yields. Furthermore, the h-BNCLE@AgNPs nanocatalyst was successfully extended to the reduction of various mono and di-nitroarenes, where the h-BNCLE@AgNPs nanocatalyst showed very good performance. The heterogeneous nature of the nanocatalyst makes it easily recoverable from the reaction mass by simple filtration or centrifugation. The recycled nanocatalyst retained excellent catalytic activity even up to several recycles, demonstrating possible industrial applicability. The synthesis and applications of the h-BNCLE@AgNPs nanocatalyst are economical and facile, producing non-toxic by-products adhering to green chemistry protocol.

Effect of Initial pH for the Decolouration of Methylene Blue in Aqueous Solution Using Nanocellulose From Durian Husk

An effective strategy for ensuring the long-term availability of accessible resources involves the utilisation of green technology that integrates plentiful resources like cellulose. Cellulose has numerous qualitative advantages, such as being biodegradable, eco-friendly, biocompatible, and rich in hydroxyl (OH) groups. Consequently, cellulose supplies are plentiful and may be replenished in the environment. Thus, cellulose is commonly employed in the packaging, healthcare, and textile sectors. An investigation was conducted to examine the impact of the initial pH on the process of decolorizing methylene blue. The data reveals that a pH level of 44.4% exhibits worse performance compared to a higher pH level. Specifically, a pH level of 7 achieves a maximum decolouration of up to 98%. The study employed methylene blue (MB) as a model for the adsorption investigation. The results of this study suggest that cellulose nanofibrils (CNF) obtained from durian husk possess favourable characteristics as an adsorbent material or as a framework for the immobilisation of nanoparticles for use in nanoelectronics applications, which is a subject of interest.

Recent development of substrates for immobilization of bimetallic nanoparticles for wastewater treatment: a review.

Bimetallic nanoparticles (BMNPs) have gained considerable attention due to their remarkable catalytic properties, making them invaluable in wastewater treatment applications. One of these challenges lies in the propensity of BMNPs to aggregate due to Van der Waals interactions, which can reduce their overall performance. Additionally, retrieving exhausted NPs from the treated solution for subsequent reuse remains a significant hurdle. Moreover, the leaching of NPs into the discharged wastewater can have harmful effects on humans as well as aquatic life. To overcome these issues, various substrates have been researched to maximize the efficiency and stability of the NPs. This review paper delves into the pivotal role of various substrates in immobilizing BMNPs, providing a comprehensive analysis of their performances, advantages, and drawbacks. The substrates encompass a diverse range of materials, including organic, inorganic, organic-inorganic, beads, fibers, and membranes. Each substrate type offers unique attributes, influencing the stability, efficiency, and recyclability of BMNPs. This review paper aims to provide an up-to-date and detailed analysis and comparison of the substrates used for the immobilization of BMNPs. This work further reviews the underlying mechanisms of the composites involved in treating pollutants from wastewater and how these mechanisms are enhanced by the synergistic effects produced by the substrate and BMNPs. Furthermore, the reusability and sustainability of these composites are discussed. Also, high-performing substrates are highlighted to give direction to future research focusing on the immobilization of BMNPs in the application of wastewater treatment.

Immobilization of Au nanoparticles on black phosphorus modified spherical covalent organic frameworks for the flow-through reduction of 4-nitrophenol

Covalent organic frameworks (COFs), due to their unique structure and morphology, manifest great potential as active substrates to support noble metals for sustainable catalytic applications. However, it is still a challenge for efficient and effective catalysis using these kinds of COFs-based catalysts. Here, black phosphorus (BP) nanosheets modified spherical COFs (SCOFs) were synthesized, followed by the immobilization of Au nanoparticles (Au NPs) to fabricate Au NPs/BP/SCOFs microspheres. The as-prepared Au NPs/BP/SCOFs microspheres were then filled in a column for the continuous catalytic reduction of 4-nitrophenol. A fast and highly efficient flow-through catalysis of 4-nitrophenol with a reduction efficiency of 99 % under the flux of 2500 L m−2 h−1 was obtained. Furthermore, a stable catalytic performance under flow-through process was exhibited with only 0.13 wt% of total Au NPs releasing after testing for 24 h. The strategy for designing COFs-based substrates with enhanced electron transfer and controllable morphology would develop a new route to promote the application of these kinds of COFs-based catalysts.

Molding Process Retaining Gold Nanoparticle Assembly Structures during Transfer to a Polycarbonate Surface.

The immobilization of gold nanoparticle (AuNP) linear surface assemblies on polycarbonate (PC) melt surface via molding is investigated. The order of the particle assemblies is preserved during the molding process. The assemblies on PC exhibit plasmonic coupling features and dichroic properties. The structure of the assemblies is quantified based on Scanning Electron Microscopy (SEM) and image analysis data using an orientational order parameter. The transfer process from mold to melt shows high structural fidelity. The order parameter of around 0.98 reflects the orientation of the lines and remains unaffected, independent of the injection direction of the melt relative to the particle lines. This is discussed in the frame of fountain flow during injection molding. The particles were permanently fixed and withstood the injection molding process, detachment of the substrate, and extraction in boiling ethanol. The plasmonic particles coupled strongly within the dense nanoparticle lines to produce anisotropic optical properties, as quantified by dichroic ratios of 0.28 and 0.52 using ultraviolet-visible-near-infrared (UV-Vis-NIR) spectroscopy. AuNP line assemblies on a polymer surface may be a basis for plasmonic devices like surface-enhanced Raman scattering (SERS) sensors or a precursor for nanowires. Their embedding via injection molding constitutes an important link between particle-self-assembly approaches for optically functional surfaces and polymer processing techniques.

Coordination-induced amidated modified polyacrylonitrile loaded ultrafine palladium nanoparticles for thermocatalytic hydrogen evolution

A promising approach for powering hydrogen fuel cells (HFCs) involves the in-situ production of hydrogen from formic acid decomposition, with Pd-based catalysts recognized as effective for formic acid dehydrogenation. However, the immobilization of ultrafine palladium nanoparticles (Pd NPs) on catalytic supports presents a challenge and necessitates further investigation into their formation mechanism. We propose a coordination-induced strategy to understand the behavior of ultrafine Pd NPs formation based on multi-functional groups. To establish the structure–activity relationship for tunable Pd microenvironment and catalytic performance, we synthesized various polyacrylonitrile (PAN) carriers through hydrolysis and amidation modification. Molecular dynamics simulations confirmed that a stronger coordination-induced microenvironment facilitates the dispersion of Pd2+, suppressing aggregation and enhancing Pd loading. Our experimental results and density functional theory (DFT) calculations demonstrated that the catalytic activity of Pd@APAN(15_1%) with ultrafine Pd NPs (1.5 nm) exhibits over 10 times higher than that of Pd@PAN NPs with the turnover of frequency climbing from 112.6 h−1 to 1309.4 h−1 at 323 K. And Pd-imine and Pd-secondary amine moieties were verified to contribute to the creation of a favorable catalysis microenvironment. This study provides new insights into the design of modified supports with various groups to load well-dispersed and ultrafine Pd for highly efficient catalysts based on a coordination-induced strategy.

Eco-friendly fabrication of MNP@MPN film capillary microreactors for enhanced catalysis and sensitive nitrite detection

A pioneering, eco-friendly methodology has been developed for the immobilization of metal nanoparticles embedded in metal phenolic networks (MNPs@MPNs) on the inner surfaces of capillary microreactors, eliminating the need for redox reagents. This innovative approach enables precise control over the MPN film thickness and the loading capacity of MNPs. The microreactor functionalized with this novel film exhibited exceptional catalytic performance in the reduction of 4-nitrophenol by sodium borohydride, achieving a near-quantitative conversion efficiency of 100%. Furthermore, we highly sensitively detected nitrite by assembling MNP@MPN microreactors as cascade reactors. The successful scale-up of this methodology to larger microreactors not only validates its versatility but also underscores its immense potential for implementation in the chemical industry, paving the way for more sustainable and efficient chemical processes.

Irradiation-assisted synthesis of smart hydrogels based on nanomagnetic semi-interpenetrating p(HEMA)/PVP networks for the cleaning of cultural heritage artifacts

Preservation of our cultural and historical heritage as a testimony to our shared past is a responsibility that demands significant attention. One of the most critical and delicate aspects of conserving such treasures is cleaning them safely and effectively. Chemical hydrogels specifically designed for cleaning cultural heritage artifacts allow for the containment and controlled release of water. Based on a generic approach, a smart nanomagnetic hydrogel was developed using a semi-interpenetrating polymer network (semi-IPN) of polyhydroxyethyl methacrylate (p(HEMA)) and polyvinyl pyrrolidone (PVP). Gamma irradiation was employed to perform simultaneous in-situ polymerization, crosslinking, and also immobilization of iron oxide magnetic nanoparticles (MNPs). The chemical and structural characteristics of the nanomagnetic hydrogel were investigated using gel content, equilibrium water content, field-emission scanning electron microscopy, magnetic properties, compressive strength, dehydration kinetics, and adhesion tests. The optimal formula for smart hydrogel was a ratio of monomer to polymer 50:50, a water content of 60 wt.%, a gamma radiation dose of 20 kGy, and 3 wt.% of MNP. Two cotton canvas case studies demonstrate the versatility and effectiveness of the selected hydrogel in removing dirt and confining the water-based cleaning system. It was found that no color leaching occurred during the cleaning process.

Green construction of self-floating polysaccharide-based hydrogels with catalytic activity for efficient organic pollutants reduction

This study employed an anionic heteropolysaccharide extracted from overgrown Enteromorpha and homopolysaccharide pullulan to fabricate a self-floating hydrogel by introducing bubble templates. Subsequently, green in-situ reduction and immobilization of silver nanoparticles (Ag NPs) in the hydrogel were successfully achieved without additional reducing agents. The heteropolysaccharide from Enteromorpha provides carboxyl and sulfate groups for Ag+ ions complexation, which is beneficial for the in-situ reduction of Ag NPs and inhibits their aggregation. The incorporation of bubble templates facilitates the creation of a hierarchical pore structure in the hydrogel, giving it self-floating properties for easy recycling, while the hierarchical network with rich anchor sites ensuring adequate traction for Ag NPs dispersion and stabilization. By adjusting polysaccharide content and using bubble templates, Ag NPs smaller than 10 nm can be obtained. The composite hydrogel exhibits tunable catalytic activity and excellent degradation towards Rhodamine B, Methyl Orange, and 4-Nitrophenol, with the normalized rate constant (knor) of 78.89, 59.08, and 30.42 min−1 g−1, respectively. Notably, the reduction efficiency remained above 98 % after 6 recycles with little leaching of Ag NPs, benefiting from its self-floating ability for easy recovery in practical applications.