FePd Nanoparticles Research Articles

Iron–palladium nanoparticle biocomposites with increased metal loading

Biocomposites containing magnetic nanoparticles have the potential to combine the unique, tunable properties of nanoparticles with the strong mechanical and environmentally sustainable properties of natural fibers like cotton. Recently, a method to synthesize Fe–Pd nanoparticles on cellulose has been developed. This study presents a detailed investigation on how the structural and magnetic properties of these nanoparticle biocomposite materials are affected by increasing metal loading with respect to the cellulose while maintaining a fixed 1:1 Fe:Pd atomic ratio. Infrared spectroscopy and electron microscopy (SEM and TEM) indicate that spherical Fe–Pd nanoparticles (approximately 3–8 nm in diameter) are distributed heterogeneously throughout the fiber matrix along with amorphous iron oxide, while XRD suggests the dominant crystalline phase within the nanoparticles is likely FePd3 under significant strain. The magnetic response of the biocomposites in static and dynamic magnetic fields (as a function of frequency and temperature) reveals a polydisperse ensemble of Fe–Pd nanoparticles with up to four distributions of blocking temperatures. The lower temperature distributions are prevalent at low metal loading. As the metal loading increases, the higher temperature distributions emerge, while the lower temperature distributions are suppressed. This result points towards enhanced nanoparticle heterogeneity and agglomeration as the metal loading increases.

Size effect for exchange interactions within Fe–Pd nanoparticles

Size effect for exchange interactions within Fe–Pd nanoparticles

Fe3O4@MOF hybrid for supercilious recovery of Au(III) and Pd(II) from e-waste and spent as catalysts for cyclohexane oxidation

Improving the economic viability of the most successful precious metal catalysts is one of the significant challenges in renewable energy production. We designed a magnetic hybrid material based on Cu-pPDA MOF and Fe3O4 nanosphere for selective recovery of Au(III) and Pd(II) from e-waste. Owing to its superior maximum adsorption capacities of 1450 and 1236 mg/g for Au (III) and Pd(II), respectively, at 45 °C with the pH of 3 and 1, the sorbed samples were converted into catalysts through an annealing process to obtain carbon supported FeAu and FePd nanoparticles catalysts (FeAu/C and FePd/C). Furthermore, these catalysts were applied for the oxidation of cyclohexane and resulted that FeAu/C catalyst exhibited higher conversion rate of cyclohexane (93.2%) than FePd/C catalyst (88.3%). Mechanistic investigations suggested that synergetic effect of Fe and Au on the supported carbon promoted better bond cleavage of the O–O bond in cyclohexyl hydroperoxide, a crucial intermediate species in the oxidation of cyclohexane. This study provides an alternate approach for the sustainable preparation of highly desired catalytic materials.

Enhanced removal of 2,4-dichlorophenol by Fe-Pd@ZIF-8 via adsorption and dechlorination

Recently, bimetallic Fe-Pd nanoparticles were integrated with metal organic frameworks (MOFs) to produce a new composite catalyst with significant potential for organic contaminant removal due to enhanced adsorption and reduction. Here, 85.9 % of 2,4-dichlorophenol (2,4-DCP) was successfully removed from aqueous solution within 120 min when using a zinc-based zeolitic imidazolate framework (ZIF-8) embedded with Fe-Pd (Fe-Pd@ZIF-8). In comparison only 77.4 and 48.3 % was removed when using ZIF-8 or Fe-Pd alone. Thus, to better understand the function of composite components (ZIF-8 and Fe-Pd) in the removal of 2,4-DCP, and the specific removal mechanism involved, Fe-Pd@ZIF-8 was characterized before and after exposure to 2,4-DCP. This comparison revealed that 2,4-DCP was adsorbed onto the surface of the composite during exposure. Moreover, while ZIF-8 maintained stability following the removal of 2,4-DCP, Fe0 was partially oxidized and Pd functioned as a catalyst in the removal process. Furthermore, kinetic studies demonstrated that the initial adsorption of 2,4-DCP conformed to a pseudo-second-order model and the subsequent reduction conformed to a pseudo-first-order model, whereas isothermal adsorption best fit the Freundlich adsorption model. This observation suggested that removal mechanism of 2,4-DCP involved both adsorption and dechlorination. Finally, Fe-Pd@ZIF-8 was applied to practically remove 2,4-DCP from wastewater, showing a 74.4 % removal efficiency which indicated that the composite was a potential new nanomaterial for practically removing organic contaminants from wastewater.

Size Effect for Exchange Interactions in Fe-Pd Nanoparticles

Size Effect for Exchange Interactions in Fe-Pd Nanoparticles

Effect of the Substrate Crystallinity on Morphological and Magnetic Properties of Fe70Pd30 Nanoparticles Obtained by the Solid-State Dewetting.

Advances in nanofabrication techniques are undoubtedly needed to obtain nanostructured magnetic materials with physical and chemical properties matching the pressing and relentless technological demands of sensors. Solid-state dewetting is known to be a low-cost and “top-down” nanofabrication technique able to induce a controlled morphological transformation of a continuous thin film into an ordered nanoparticle array. Here, magnetic FePd thin film with 30 nm thickness is deposited by the co-sputtering technique on a monocrystalline (MgO) or amorphous (SiN) substrate and, subsequently, annealed to promote the dewetting process. The different substrate properties are able to tune the activation thermal energy of the dewetting process, which can be tuned by depositing on substrates with different microstructures. In this way, it is possible to tailor the final morphology of FePd nanoparticles as observed by advanced microscopy techniques (SEM and AFM). The average size and height of the nanoparticles are in the ranges 150–300 nm and 150–200 nm, respectively. Moreover, the induced spatial confinement of magnetic materials in almost-spherical nanoparticles strongly affects the magnetic properties as observed by in-plane and out-of-plane hysteresis loops. Magnetization reversal in dewetted FePd nanoparticles is mainly characterized by a rotational mechanism leading to a slower approach to saturation and smaller value of the magnetic susceptibility than the as-deposited thin film.

Iron-Palladium Decorated Carbon Nanotubes Achieve Radiosensitization via Reactive Oxygen Species Burst.

Radiotherapy is recommended as a modality for cancer treatment in clinic. However, cancerous cells were resistant to therapeutic irradiation due to its DNA repair. In this work, single-walled carbon nanotubes with unique physical properties of hollow structures and high specific surface area were introduced as carrier for iron-palladium (FePd) to obtain iron-palladium decorated carbon nanotubes (FePd@CNTs). On one hand, FePd nanoparticles possess significant ability in radiosensitization as previously reported. On the other hand, carbon nanotubes offer higher efficiency in crossing biological barriers, inducing the accumulation and retention of FePd nanoparticles within tumor tissue. In order to verify the radiosensitization effect of FePd@CNTs, both in vitro and in vivo experiments were conducted. These experiments showed that the FePd@CNTs exhibited remarkably better radiosensitization effect and more obvious accumulation than FePd NPs, suggesting a potential of FePd@CNTs in radiosensitization.

Thickness-dependent L10 ordering behavior in polycrystalline Fe–Pd nanoparticle films on glass substrates

The dependence of the L10 ordering, magnetic properties and microstructure on film thickness of the Fe51Pd49 nanoparticle films deposited at 800 °C was investigated. The L10 ordered phase and hard magnetic properties were found for the samples with the thickness less than 30 nm. As the thickness was increased to 45 nm and thicker, the samples exhibited the A1 disordered phase and soft magnetic properties. The lack of heterogeneous nucleation sites is responsible for the A1 disordered phase in the thicker FePd samples, which was confirmed by the results of microstructural and crystallographic analyses. The long term re-annealing at a lower temperature (600 °C for 8 h) can induce the L10 ordering of the large size FePd nanoparticles originally composed of the A1 phase, which also supports the statement that the heterogeneous nucleation sites play an important role on L10 ordering of the FePd films.

Thermoresponsive PNIPAm–PMMA-Functionalized PVDF Membranes with Reactive Fe–Pd Nanoparticles for PCB Degradation

Fe–Pd nanoparticles are immobilized in stimuli-responsive poly-N-isopropylacrylamide (PNIPAm)- and poly-methyl methacrylate-functionalized polyvinylidene fluoride membranes using ion exchange for 2...

Eutectic crystallized FePd nanoparticles for liquid metal magnet.

Magnetically hard nanoparticles have been widely explored in colloidal solution synthesis, while a high temperature-induced phase transformation is indispensable to achieve its high magnetocrystalline anisotropy. However, a long-standing challenge of magnetic nanoparticles is the inaccessibility of size-controlled growth without sintering-induced agglomeration. Here, we report a universal one-pot eutectic reaction scheme of magnetically hard FePd nanoparticles, in which the crystallization conditions are critical for its magnetic performance. We demonstrate that the stoichiometry between transition metal and eutectic salt and sintering temperature can play an important role in the magnetic coercivity of FePd nanoparticles. In addition, gallium liquid metal is employed as the conductivity filler for the formation of a magnetorheological fluid after mixing with metallic FePd nanoparticles. The liquid composite shows a high metallic and thermal conductivity as an unconventional cooling metallic ferrofluid conductor, and we further demonstrate its potential application in sensors, conductors and thermal interfaces.

Catalytic degradation of TCE by a PVDF membrane with Pd-coated nanoscale zero-valent iron reductant

Trichloroethylene (TCE) has serious threat to ecosystem. Fe-Pd nanoparticles (NPs) are good materials for catalytic degradation of TCE but still face severe challenges including easy fouling, agglomeration, deactivation and difficult separation and reuse etc. To overcome these drawbacks, we have constructed a novel structured PVDF/Fe-Pd NPs composite membrane with nanosized surface pores to execute the TCE degradation. Results indicate the degradation shows pseudo first-order reaction kinetics and high degradation rate in the static state degradation. Furthermore, the degradation ability can be enhanced by increasing Fe and Pd contents, the degradation temperature or decreasing the degradation pH value. However, the degradation is essentially limited by the diffusion. Thus, the cross-flow degradation is further applied to promote the diffusion. By this operating model, the degradation ability of the composite membrane can be greatly improved. More importantly, the reactants always keep the purity in the membrane surface side and can be controlled to enter the membrane pore for catalytic degradation. Thus, products can be timely discharged via the membrane pores and the side reactions between reactants and products can be largely reduced. In addition, the nanosized surface pores can also prevent the Fe-Pd NPs from being fouled. In a word, the novel composite membrane shows strong degradation ability, good stability and convenient operating ability for the TEC catalytic degradation.

Lignocellulose-stabilized iron-palladium nanomagnetic biocomposites

In this study we report the synthesis and characterization of superparamagnetic Fe-Pd (1–75 at.% Fe) nanomagnets grown within a lignocellulose fiber matrix for future advanced material applications. The small (~5 nm diameter) Fe-Pd nanoparticles are crystalline with spherical shape and evenly dispersed throughout the lignocellulose support while preserving the structure of the biopolymer matrix. Material characterization of the as-formed biocomposites confirms primarily zero-valent Pd-Fe alloy with a thin surface oxide layer. Normal superparamagnetic behavior consistent with extremely small nanoparticle size is measured, including increasing measured blocking temperature with increasing Fe concentration. Finally, important mass loading effects of metallic nanoparticles within the lignocellulose matrix are measured and discussed.

Continuous rapid dechlorination of p-chlorophenol by Fe-Pd nanoparticles promoted by procyanidin

Nanoscale zero-valent iron has been widely applied in environmental remediation and toxic waste treatment, especially for the degradation of persistent organic pollutants (POPs). However, the dechlorination activity of Fe nanoparticles (Fe NPs) can be suppressed by the precipitation of iron oxides generated from the corrosion of Fe-Pd NPs under alkaline conditions, leading to a decreased dechlorination efficiency. Faced with this challenge, we report a highly effective dechlorination system that functions over a broad pH range and especially well under alkaline conditions in this work. Procyanidin (PROC), a natural polyphenol, was utilized as a stabilizer to manipulate the size distribution of Fe-Pd NPs and, more importantly, as a scavenger of Fe ions to prevent iron oxide precipitation. Experiments and theoretical calculations reveal that the generated Fe ions was mainly present in the form of bis- and tris-PROC-Fe complexes in the reaction solution. Compared with pristine Fe-Pd NPs, the PROC-modified Fe-Pd NPs had a dechlorination efficiency that was increased 20-fold (pH 9.0). Notably, a normalized rate constant was enhanced by more than 2 orders of magnitude compared to the previously reported dechlorination systems. The PROC-modified Fe-Pd NPs showed excellent dechlorination efficiency over a wide pH range (2.3–13.0).

Effect of N on the microstructure and magnetic properties of FePdSi nanocomposite films

FePdSi and FePdSiN nanocomposite films were fabricated successfully on quartz glass substrate by direct current reactive magnetron sputtering. Under the same preparation parameters, the Fe/Pd ratio of FePdSi and FePdSiN films was unbalanced, which emerged obvious difference in morphology, microstructure and magnetic properties. The addition of N played an important role on the molecular free path and sputtering rate of Fe–Pd–Si film. Preferential combination of N with Si formed an amorphous Si–N matrix between the FePd nanoparticles, which improved the coercivity, maximum magnetic energy product and remanence ratio up to 2.8 kOe, 9.4 MGOe and 0.99 after thermal treatment at 550 °C, respectively. The mechanism was proposed to account for this unique growth technique.

Dechlorination of p-Chlorophenol by Fe-Pd Nanoparticles Promoted by Poly (γ-glutamic acid)–Dopamine Composite

Palladium-doped nanoscale zerovalent iron nanoparticles (Fe-Pd NPs) was fabricated and stabilized by poly (γ-glutamic acid)–Dopamine composite (PGA-DA). The fabricated nanoparticles had high dechlorination activity towards p-Chlorophenol (p-CP). PGA-DA modified Fe-Pd NPs significantly outperformed PGA modified ones in catalytic activities even in weak alkaline condition. Fe-Pd NPs@PGA-DA (10 mg PGA-DA and 0.4 wt% Pd loading) could achieve 100 % p-CP removal within 60 min. It is worth mentioning that the presence of DA alone could overwhelm dechlorination capacity of Fe-Pd NPs toward p-CP. The coordination bonding between catechol and Fe ions was also investigated in detail. This study demonstrated that PGA-DA is a promising modifier and stabilizer for Fe-Pd NPs, which was expected to be applied in real environmental remediation technology.

Tannic acid-assisted fabrication of Fe-Pd nanoparticles for stable rapid dechlorination of two organochlorides

Nanoscale zero valent iron (nZVI) and bimetallic nZVI has been widely applied to remove various contaminants from water and soil, but their activities can be greatly reduced due to the precipitation of the generated Fe ions. Here we adopted tannic acid (TA) as stabilizer to synthesize high activity Fe-Pd nanoparticles (NPs) and scavenger of the generated Fe ions to keep the rapid dechlorination of two organochlorides. Inductively coupled plasma optical emission spectrometry and UV–vis spectroscopy measurements indicated the generated Fe ions were harvested by TA and formed bis- and tris-TA-iron complexes in the dechlorination solution. TA promoted 40-fold and 10-fold increase in dechlorination efficiency of p-chlorophenol and florfenicol attributing to the complexation of Fe ion by TA. This strategy may inspire novel ways to deal with the passivation of nZVI caused by the precipitation of Fe ions and benefits for the developing of longevity and high-efficient nZVI materials.

Formation of free-standing magnetic particles by solid-state dewetting of Fe80Pd20 thin films

An alternative process to produce magnetic FePd nanoparticles dispersed in liquid solution exploiting a “top-down” strategy is here reported. This process is based on the solid-state dewetting of a Fe80Pd20 thin film to produce magnetic isolated islands array attached on a solid substrate. The subsequent detachment from the substrate offers the possibility to obtain free-standing magnetic nanoparticles for different applications. An adequate choice of the initial thickness of Fe80Pd20 thin film, annealing time and annealing temperature allows to finely tune the final size and shape of free-standing magnetic nanoparticles. A detailed study on the influence of latter parameters on islands morphology is here presented by SEM images analysis whereas the Johnson-Mehl-Avrami model is employed to extract the kinetics parameters of dewetting process. Room-temperature hysteresis loops and first-order reversal curves are measured in order to investigate the evolution of magnetic properties as a function of dewetting stage.

One-pot synthesis of ferromagnetic FePd nanoparticles from single-source organometallic precursors and size effect of metal fraction in polymer chain

The accurate regulation of the size of the ferromagnetic nanoparticle synthesized from the one-pot pyrolysis of metallopolymer is a challenging topic to date. A bimetallic complex TPy-FePd-1 was prepared and used as a single-source precursor to synthesize ferromagnetic FePd nanoparticles (NPs) by one-pot pyrolysis. The resultant FePd NPs have a mean particle size of 19.8 nm and show a coercivity of 1.02 kOe. In addition, the labile ligand NCMe in TPy-FePd-1 was easily substituted by a pyridyl group. A random copolymer PS-P4VP was used to coordinate with TPy-FePd-1, and the as-synthesized metallopolymer made the metal fraction disperse evenly along the flexible chain. Investigation of FePd NPs from the bimetallic polymers with different metal fractions was also made, and the size of the resultant nanoparticles could be easily controlled by tuning the metal fraction in the polymer.

Electrospun and functionalized PVDF/PAN nanocatalyst-loaded composite for dechlorination and photodegradation of pesticides in contaminated water.

A novel approach for the electrospinning and functionalization of nanocatalyst-loaded polyvinylidene fluoride/polyacrylonitrile (PVDF/PAN) composite grafted with acrylic acid (AA; which form polyacrylic acid (PAA) brush) and decorated with silver (Ag/PAN/PVDF-g-PAA-TiO2/Fe-Pd) designed for the dechlorination and photodegradation of pesticides was carried out. PAN was used both as a nitrogen dopant as well as a co-polymer. Smooth nanofibers were obtained by electrospinning a solution of 12:2wt.% PVDF/PAN blend using dimethylformamide (DMF) as solvent. The nanofibers were grafted with AA by free-radical polymerization using 2,2'azobis(2-methylpropionitrile) (AIBN) as initiator. Both bimetallic iron-palladium (Fe-Pd) and titania (TiO2) nanoparticles (NP) were anchored on the grafted nanofibers via the carboxylate groups by in situ and ex situ synthesis. The Fe-Pd and nitrogen-doped TiO2 nanoparticles were subsequently used for dechlorination and oxidation of target pollutants (dieldrin, chlorpyrifos, diuron, and fipronil) to benign products. Structural and chemical characterizations of the composites were done using various techniques. These include surface area and porosity analyzer (ASAP) using the technique by Brunner Emmett Teller (BET), Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscope (TEM) analyses were done. After dechlorination, the transformation products (TPs) for dieldrin, chlorpyrifos, diuron, and fipronil were obtained and identified using two-dimensional gas chromatography (time-of-flight) with a mass spectrometer detector (GCxGC-TOFMS). Analysis of total organic carbon (TOC) was carried out and used to extrapolate percentage mineralization. Experimental results showed that dechlorination efficiencies of 96, 93, 96, and 90% for 1, 2, 2, and 3h treatment period were respectively achieved for 5ppm solutions of dieldrin, chlorpyrifos, diuron, and fipronil. The dechlorination of dieldrin, diuron, and fipronil follows first-order kinetics while that of chlorpyrifos followed pseudo-first order. Mineralization performance of 34 to 45% were recorded when Fe-Pd was used, however upon electrospinning, doping, and grafting (Ag/PAN/PVDF-g-PAA-TiO2/Fe-Pd composite); it significantly increased to 99.9999%. This composite reveals great potential for dechlorination and mineralization of pesticides in contaminated water.

Selective reduction of nitrate into nitrogen using Fe–Pd bimetallic nanoparticle supported on chelating resin at near-neutral pH

Nano zero valent iron (nZVI) has emerged as a promising water treatment technology for reduction of contaminants. Unfortunately, for nitrate reduction by nZVI, near 100% of nitrate was converted to undesired ammonia (NH3) and not to nontoxic nitrogen (N2). In this study, supported bimetallic Fe–Pd nanoparticles were prepared by loading Fe and Pd on chelating resin (DOW 3N) by two different methods. The effect of the preparation method, solution pH and Pd loading on the reactivity and selectivity of Fe–Pd composites for nitrate removal was investigated at near-neutral pH in unbuffered solution. The results suggest that DOW 3N-Fe/Pd, which was prepared by loading Pd firstly and then Fe on DOW 3N, showed a remarkable nitrate removal (>95%). The selectivity to N2 was increased with the increase of Pd content and solution pH; the N2 selectivity of 69.2% was obtained at pH 6.75 using DOW 3N-Fe/Pd with 8wt.% Pd–8wt.% Fe. The high selectivity to N2 benefited from the closer contact distance between Pd and Fe on the surface of DOW 3N-Fe/Pd and low intraparticle diffusion resistance.