Preparation of novel palladium nanoparticles supported on magnetic iron oxide and their catalytic application in the synthesis of 2‐imino‐3‐phenyl‐2,3‐dihydrobenzo[d]oxazol‐5‐ols

Novel Pd nanoparticles were prepared in five successive stages: 1) preparation of the Fe₃O₄ magnetic nanoparticles (Fe₃O₄ MNPs), 2) coating of Fe₃O₄ MNPs with SiO₂ (Fe₃O₄@SiO₂), 3) functionalization of Fe₃O₄@SiO₂ with 3‐chloropropyltrimethoxy‐ silane (CPTMS) ligand (Fe₃O₄@SiO₂@CPTMS), 4) further functionalization with 3,5‐diamino‐1,2,4‐triazole (DAT) ligand (Fe₃O₄@SiO₂@CPTMS @DAT), and 5) the complexation of Fe₃O₄@SiO₂@CPTMS@DAT with PdCl₂ (Fe₃O₄@SiO₂@CPTMS@ DAT@Pd). Then, the obtained Pd nano‐catalyst characterized by different methods such as the elemental analysis (CHN), FT‐IR, XRD, EDX, SEM, TEM, TG‐DTA and VSM. Finally, the Pd catalyst was applied for the synthesis of various 2‐imino‐3‐phenyl‐2,3‐dihydrobenzo[d]oxazol‐5‐ols.     

One Step Preparation of Reduced Graphene Oxide/Pd–Fe3O4@Polypyrrole Composites and Their Application in Catalysis

The simple preparation of catalysts with superior catalytic activity and good reusability is highly desirable. Herein, we report a novel strategy to construct reduced graphene oxide (rGO)/Pd–Fe₃O₄@polypyrrole (PPy) catalysts with Pd and Fe₃O₄ nanoparticles anchored on a rGO nanosheet surface and wrapped in a PPy shell. The synthesis and assembly of both the Pd and Fe₃O₄ nanoparticles, the preparation of the PPy layer, and the reduction of graphene oxide nanosheets were finished in one step. In the system, the PPy layer not only prevented aggregation of Pd and Fe₃O₄ nanoparticles, but also generated a synergistic effect with precursor Pd²⁺ ions, which led to a high dispersity of as‐prepared Pd nanoparticles. Although the procedure was simplified to one step, the catalytic activity and reusability were not sacrificed. In the reduction of 4‐nitrophenol, their catalytic performance was better than that in recent reports. Moreover, the catalysts showed good reusability owing to their magnetic properties.     

Synergistic Ternary Composite (Carbon/Fe3O4@Graphene) with Hollow Microspherical and Robust Structure for Li‐Ion Storage

The electrode materials with hollow structure and/or graphene coating are expected to exhibit outstanding electrochemical performances in energy‐storage systems. 2D graphene‐wrapped hollow C/Fe₃O₄ microspheres are rationally designed and fabricated by a novel facile and scalable strategy. The core@double‐shell structure SPS@FeOOH@GO (SPS: sulfonated polystyrene, GO: graphene oxide) microspheres are first prepared through a simple one‐pot approach and then transformed into C/Fe₃O₄@G (G: graphene) after calcination at 500 °C in Ar. During calcination, the Kirkendall effect resulting from the diffusion/reaction of SPS‐derived carbon and FeOOH leads to the formation of hollow structure carbon with Fe₃O₄ nanoparticles embedded in it. In the rationally constructed architecture of C/Fe₃O₄@G, the strongly coupled C/Fe₃O₄ hollow microspheres are further anchored onto 2D graphene networks, achieving a strong synergetic effect between carbon, Fe₃O₄, and graphene. As an anode material of Li‐ion batteries (LIBs), C/Fe₃O₄@G manifests a high reversible capacity, excellent rate behavior, and outstanding long‐term cycling performance (1208 mAh g^?1 after 200 cycles at 100 mA g^?1).     

Functionalization of superparamagnetic Fe3O4@SiO2 nanoparticles with a Cu(II) binuclear Schiff base complex as an efficient and reusable nanomagnetic catalyst for N‐arylation of α‐amino acids and nitrogen‐containing heterocycles with aryl halides

Fe₃O₄@SiO₂ nanoparticles was functionalized with a binuclear Schiff base Cu(II)‐complex (Fe₃O₄@SiO₂/Schiff base‐Cu(II) NPs) and used as an effective magnetic hetereogeneous nanocatalyst for the N‐arylation of α‐amino acids and nitrogen‐containig heterocycles. The catalyst, Fe₃O₄@SiO₂/Schiff base‐Cu(II) NPs, was characterized by Fourier transform infrared (FTIR) and ultraviolet‐visible (UV‐vis) analyses step by step. Size, morphology, and size distribution of the nanocatalyst were studied by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and dynamic light scatterings (DLS) analyses, respectively. The structure of Fe₃O₄ nanoparticles was checked by X‐ray diffraction (XRD) technique. Furthermore, the magnetic properties of the nanocatalyst were investigated by vibrating sample magnetometer (VSM) analysis. Loading content as well as leaching amounts of copper supported by the catalyst was measured by inductive coupled plasma (ICP) analysis. Also, thermal studies of the nanocatalyst was studied by thermal gravimetric analysis (TGA) instrument. X‐ray photoelectron spectroscopy (XPS) analysis of the catalyst revealed that the copper sites are in +2 oxidation state. The Fe₃O₄@SiO₂/Schiff base‐Cu(II) complex was found to be an effective catalyst for C–N cross‐coupling reactions, which high to excellent yields were achieved for α‐amino acids as well as N‐hetereocyclic compounds. Easy recoverability of the catalyst by an external magnet, reusability up to eight runs without significant loss of activity, and its well stability during the reaction are among the other highlights of this catalyst.     

One‐Pot Synthesis of Pomegranate‐Structured Fe3O4/Carbon Nanospheres‐Doped Graphene Aerogel for High‐Rate Lithium Ion Batteries

A unique hierarchically nanostructured composite of iron oxide/carbon (Fe₃O₄/C) nanospheres‐doped three‐dimensional (3D) graphene aerogel has been fabricated by a one‐pot hydrothermal strategy. In this novel nanostructured composite aerogel, uniform Fe₃O₄ nanocrystals (5–10 nm) are individually embedded in carbon nanospheres (ca. 50 nm) forming a pomegranate‐like structure. The carbon matrix suppresses the aggregation of Fe₃O₄ nanocrystals, avoids direct exposure of the encapsulated Fe₃O₄ to the electrolyte, and buffers the volume expansion. Meanwhile, the interconnected 3D graphene aerogel further serves to reinforce the structure of the Fe₃O₄/C nanospheres and enhances the electrical conductivity of the overall electrode. Therefore, the carbon matrix and the interconnected graphene network entrap the Fe₃O₄ nanocrystals such that their electrochemical function is retained even after fracture. This novel hierarchical aerogel structure delivers a long‐term stability of 634 mA h g^?1 over 1000 cycles at a high current density of 6 A g^?1 (7 C), and an excellent rate capability of 413 mA h g^?1 at 10 A g^?1 (11 C), thus exhibiting great potential as an anode composite structure for durable high‐rate lithium‐ion batteries.     

Preparation and characterization of palladium immobilized on silica‐coated Fe3O4 and its catalytic performance for Suzuki reaction under microwave irradiation

Supported palladium catalyst (Pd/Fe₃O₄@SiO₂) was easily prepared by supporting PdCl₂ on silica‐coated magnetic nanoparticles Fe₃O₄ in ethylene glycol. The as‐prepared sample was characterized by infrared spectroscopy (IR), X‐ray diffraction (XRD) and X‐ray photoelectron spectrometer (XPS). The formation of active specie Pd(0) was confirmed by XRD and XPS, and the Pd loading for the fresh and recovered catalyst was determined by atomic absorption spectroscopy (AAS). Pd/Fe₃O₄@SiO₂ was employed for the synthesis of biphenyl derivatives via Suzuki reaction. In terms of the yield of biphenyl, the supported catalyst displayed nearly equal catalytic performance to that of homologous PdCl₂ under microwave irradiation for 30 min but higher than that obtained by traditional heating method for 12 h. The catalytic performance of Pd/Fe₃O₄@SiO₂ for Suzuki reactions involving various aryl halides and arylboronic acids were also examined. Impressive yield of biphenyl at 68.2% was obtained even in the presence of unreactive aryl chlorides. Pd/Fe₃O₄@SiO₂ was recovered by a permanent magnet and directly reused in the next run, and no obvious deactivation was observed for up to 6 times. Copyright © 2016 John Wiley & Sons, Ltd.     

Palladium Nanoparticles Bonded to Two‐Dimensional Iron Oxide Graphene Nanosheets: A Synergistic and Highly Reusable Catalyst for the Tsuji–Trost Reaction in Water and Air

Low cost, high activity and selectivity, convenient separation, and increased reusability are the main requirements for noble‐metal‐nanocatalyst‐catalyzed reactions. Despite tremendous efforts, developing noble‐metal nanocatalysts to meet the above requirements remains a significant challenge. Here we present a general strategy for the preparation of strongly coupled Fe₃O₄ and palladium nanoparticles (PdNPs) to graphene sheets by employing polyethyleneimine as the coupling linker. Transmission electron microscopic images show that Pd and Fe₃O₄ nanoparticles are highly dispersed on the graphene surface, and the mean particle size of Pd is around 3 nm. This nanocatalyst exhibits synergistic catalysis by Pd nanoparticles supported on reduced graphene oxide (rGO) and a tertiary amine of polyethyleneimine (Pd/Fe₃O₄/PEI/rGO) for the Tsuji–Trost reaction in water and air. For example, the reaction of ethyl acetoacetate with allyl ethyl carbonate afforded the allylated product in more than 99 % isolated yield, and the turnover frequency reached 2200 h^?1. The yield of allylated products was 66 % for Pd/rGO without polyethyleneimine. The catalyst could be readily recycled by a magnet and reused more than 30 times without appreciable loss of activity. In addition, only about 7.5 % of Pd species leached off after 20 cycles, thus rendering this catalyst safer for the environment.     

Flexible Magnetic Nanoparticles–Reduced Graphene Oxide Composite Membranes Formed by Self‐Assembly in Solution

A facile and robust route for the pre‐synthesized Fe₃O₄ nanoparticles (NPs) exclusively assembled on both sides of reduced graphene oxide (RGO) sheets with tunable density forming two‐dimensional NPs composite membranes is developed in solution. The assembly is driven by electrostatic attraction, and the nanocomposite sheets display considerable mechanical robustness, such as it can sustain supersonic and solvothermal treatments without NPs falling off, also, can freely float in solution and curl into a tube. The obtained two‐dimensional composite grain membranes exhibit superparamagnetic behavior at room temperature but responds astutely to an external magnetic field. In addition, these magnetic composite membranes show an enhanced absorption capability for microwaves. The grain sheets are attractive for biomedical, sensors, environmental applications and electric‐magnetic devices benefited from large surfaces, high magnetization moment, and superparamagnetic properties. The effective integration of oxide nanocrystals on RGO sheets provides a new way to design semiconductor–carbon nanocomposites for nanodevices or catalytic applications.     

CeO2‐Based Pd(Pt) Nanoparticles Grafted onto Fe3O4/Graphene: A General Self‐Assembly Approach To Fabricate Highly Efficient Catalysts with Magnetic Recyclable Capability

New Pd(Pt) catalysts have been fabricated by assembling multicomponents of Fe₃O₄ and CeO₂/Pd(Pt) on the surface of reduced graphene oxide (RGO) nanosheets in layers. The as‐obtained Pd(Pt) catalysts exhibit extremely high catalytic activity in the selective hydrogenation reaction of nitrobenzene. Owing to the presence of Fe₃O₄, the catalysts can be easily recycled from the catalytic system through magnetic separation. Their high activity, stability, and magnetic recyclability make the as‐obtained hybrids very promising as catalysts in catalytic applications. Compared to other traditional multishell magnetic catalysts that were prepared by means of layer‐by‐layer technology, our process is much more facile and more easily controlled.     

Adsorption of acid red 114 and reactive black 5 in aqueous solutions on dendrimer‐conjugated magnetic nanoparticles

The adsorption of the dyes Acid Red 114 and Reactive Black 5 in aqueous solutions on polyhydroxyl dendrimer magnetic nanoparticles (Fe₃O₄@SiO₂‐TRIS) was studied in a batch system. The Fe₃O₄@SiO₂‐TRIS NPs were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, and transmission electron microscopy. Experiments were performed under different conditions such as the initial dye concentration, adsorbent dose, and pH. The pseudo‐second‐order model provided a very good fit for the two anionic dyes. The Langmuir and Freundlich adsorption models were used to describe the equilibrium isotherms at different temperatures, and the former agreed very well with the experimental data. However, the adsorption capacity of Fe₃O₄@SiO₂‐TRIS NPs was reduced during surface modification, which could be due to the dye occupying the binding sites of the dendrimer. Thermodynamic parameters, namely the change in free energy (ΔG⁰), enthalpy (ΔH⁰), and entropy (ΔS⁰), were also determined.     

Magnetically recoverable copper nanorods and their catalytic activity in Ullmann cross‐coupling reaction

A novel polydentate ligand supported on Fe₃O₄@SiO₂ was designed and demonstrated for the synthesis of Cu nanorods. The Fe₃O₄@SiO₂/EP.EN.EG@Cu was characterized using X‐ray diffraction, thermogravimetric analysis, transmission electron microscopy, energy‐dispersive X‐ray spectroscopy and vibrating sample magnetometry. The Fe₃O₄@SiO₂/EP.EN.EG@Cu showed excellent catalytic efficiency for the cross‐coupling reaction of nitrogen‐containing heterocycles with aryl halides. The catalyst could be effectively separated from the reaction mixture by simply applying an external magnetic field and reused at least five times without loss of activity.     

A Comparative Study of CO Oxidation on Nitrogen‐ and Phosphorus‐Doped Graphene

The geometry, electronic structure, and catalytic properties of nitrogen‐ and phosphorus‐doped graphene (N‐/P‐graphene) are investigated by density functional theory calculations. The reaction between adsorbed O₂ and CO molecules on N‐ and P‐graphene is comparably studied via Langmuir–Hinshelwood (LH) and Eley–Rideal (ER) mechanisms. The results indicate that a two‐step process can occur, namely, CO+O₂→CO₂+O_ads and CO+O_ads→CO₂. The calculated energy barriers of the first step are 15.8 and 12.4 kcal mol^?1 for N‐ and P‐graphene, respectively. The second step of the oxidation reaction on N‐graphene proceeds with an energy barrier of about 4 kcal mol^?1. It is noteworthy that this reaction step was not observed on P‐graphene because of the strong binding of O_ads species on the P atoms. Thus, it can be concluded that low‐cost N‐graphene can be used as a promising green catalyst for low‐temperature CO oxidation.     

Self‐Assembling Synthesis of Free‐standing Nanoporous Graphene–Transition‐Metal Oxide Flexible Electrodes for High‐Performance Lithium‐Ion Batteries and Supercapacitors

The synthesis of nanoporous graphene by a convenient carbon nanofiber assisted self‐assembly approach is reported. Porous structures with large pore volumes, high surface areas, and well‐controlled pore sizes were achieved by employing spherical silica as hard templates with different diameters. Through a general wet‐immersion method, transition‐metal oxide (Fe₃O₄, Co₃O₄, NiO) nanocrystals can be easily loaded into nanoporous graphene papers to form three‐dimensional flexible nanoarchitectures. When directly applied as electrodes in lithium‐ion batteries and supercapacitors, the materials exhibited superior electrochemical performances, including an ultra‐high specific capacity, an extended long cycle life, and a high rate capability. In particular, nanoporous Fe₃O₄–graphene composites can deliver a reversible specific capacity of 1427.5 mAh g^?1 at a high current density of 1000 mA g^?1 as anode materials in lithium‐ion batteries. Furthermore, nanoporous Co₃O₄–graphene composites achieved a high supercapacitance of 424.2 F g^?1. This work demonstrated that the as‐developed freestanding nanoporous graphene papers could have significant potential for energy storage and conversion applications.     

Monomer Protonation‐Dependent Surface Polymerization to Achieve One‐Step Grafting Cross‐Linked Poly(4‐Vinylpyridine) Onto Core–Shell Fe3O4@SiO2 Nanoparticles

Functional polymer‐grafting silica nanoparticles hold great promise in diverse applications such as molecule recognition, drug delivery, and heterogeneous catalysis due to high density and uniform distribution of functional groups and their tunable spatial distance. However, conventional grafting methods from monomers mainly consist of one or more extra surface modification steps and a subsequent surface polymerization step. A monomer protonation‐dependent surface polymerization strategy is proposed to achieve one‐step uniform surface grafting of cross‐linked poly(4‐vinylpyridine) (P4VP) onto core–shell Fe₃O₄@SiO₂ nanostructures. At an approximate pH, partially protonated 4VP sites in aqueous solution can be strongly adsorbed onto deprotonated silanol groups ( Si O⁻) onto Fe₃O₄@SiO₂ nanospheres to ensure prior polymerization of these protonated 4VP sites exclusively onto Fe₃O₄@SiO₂ nanoparticles and subsequent polymerization of other 4VP and divinylbenzene monomers harvested by these protonated 4VP monomers onto Fe₃O₄@SiO₂ nanoparticles, thereby achieving direct grafting of cross‐linked P4VP macromolecules onto Fe₃O₄@SiO₂ nanoparticles.     

Hiyama cross‐coupling reaction using Pd(II) nanocatalyst immobilized on the surface of Fe3O4@SiO2

We report a simple process for the synthesis of Fe₃O₄@SiO₂/APTMS (APTMS = 3‐aminopropyltrimethoxysilane) core–shell nanocatalyst support. The new nanocatalyst was prepared by stabilization of Pd(cdha)₂ (cdha = bis(2‐chloro‐3,4‐dihydroxyacetophenone)) on the surface of the Fe₃O₄@SiO₂/APTMS support. The structure and composition of this catalyst were characterized using various techniques. An efficient method was developed for the synthesis of a wide variety of biaryl compounds via fluoride‐free Hiyama cross‐coupling reactions of aryl halides with arylsiloxane, with Fe₃O₄@SiO₂/APTMS/Pd(cdha)₂ as the catalyst under reaction conditions. This methodology can be performed at 100°C through a simple one‐pot operation using in situ generated palladium nanoparticles. High catalytic activity, quick separation of catalyst from products using an external magnetic field and use of water as green solvent are attributes of this protocol.     

Improvement on physical properties of polyethersulfone membranes modified by poly(1‐vinylpyrrolidone) grafted magnetic Fe3O4@SiO2 nanoparticles

Polyethersulfone (PES) and poly(1‐vinylpyrrolidone) (PVP) were used to prepare ultrafiltration membranes with grafted Fe₃O₄ magnetic nanoparticles (PVP‐g‐Fe₃O₄@SiO₂). The structure of synthesized PVP‐g‐Fe₃O₄@SiO₂ was confirmed by FT‐IR and SEM analysis. Physical properties of blend membranes such as thermal resistance, Tensile strength, water uptake, and hydrophilicity were also investigated. Blended membranes of PES/PVP‐g‐Fe₃O₄@SiO₂ have exhibited higher thermal resistance due to increasing the modified nanoparticle content. The hydrophilicity of the synthesized PES/PVP‐g‐Fe₃O₄@SiO₂ membranes also improved by increasing the PVP‐g‐Fe₃O₄@SiO₂ content. As expected, increasing the hydrophilicity of blended membrane, caused enhancement of fouling resistance in membranes. Results showed that the content of PVP‐g‐Fe₃O₄@SiO₂ has different effects on the properties of synthesized composite membranes. Despite increasing the content of PVP‐g‐Fe₃O₄@SiO₂ has a negative effect on elongation, positive effects on maximum stress was observed. Moreover, the water uptake of synthesized membranes was significantly enhanced in comparison to other similar studies.     

Recent Developments in the Plant‐Mediated Green Synthesis of Ag‐Based Nanoparticles for Environmental and Catalytic Applications

Among different metallic nanoparticles, sliver nanoparticles (Ag NPs) are one of the most essential and fascinating nanomaterials. Importantly, among the metal based nanoparticles, Ag NPs play a key role in various fields such as biomedicine, biosensors, catalysis, pharmaceuticals, nanoscience and nanotechnology, particularly in nanomedicine. A main concern about the chemical synthesis of Ag NPs is the production of hazardous chemicals and toxic wastes. To overcome this problem, many research studies have been carried out on the green synthesis of Ag NPs using green sources such as plant extracts, microorganisms and some biopolymers without formation of hazardous wastes. Among green sources, plants could be remarkably valuable to exploring the biosynthesis of Ag NPs. In this review, the green synthesis of Ag‐based nanocatalysts such as Ag NPs, AgPd NPs, Au?Ag NPs, Ag/AgPd NPs, Ag/Cu NPs, Ag@AgCl NPs, Au?Ag@AgCl nanocomposite, Ag?Cr‐AC nanocomposite and Ag NPs immobilized on various supports such as Natrolite zeolite, bone, ZnO, seashell, hazelnut shell, almond shell, SnO₂, perlite, ZrO₂, TiO₂, α‐Al₂O₃, CeO₂, reduced graphene oxide (rGO), h‐Fe₂O₃@SiO₂, and Fe₃O₄ using numerous plant extracts as reducing and stabilizing agents in the absence of hazardous surfactant and capping agents has been focused. This work describes the state of the art and future challenges in the biosynthesis of Ag‐based nanocatalysts. The fact about the application of living plants in metal nanoparticle (MNPs) industry is that it is a more economical and efficient biosynthesis biosynthetic procedure. In addition, the catalytic activities of the synthesized, Ag‐based recyclable nanocatalysts using various plant extracts in several chemical reactions such as oxidation, reduction, coupling, cycloaddition, cyanation, epoxidation, hydration, degradation and hydrogenation reactions have bben extensively discussed.     

Direct Electrochemistry of Hemoglobin Based on Fe3O4@SiO2 Nanoparticles Modified Electrode

A biosensor based on hemoglobin‐Fe₃O₄@SiO₂ nanoparticle bioconjunctions modified indium‐tin‐oxide (Hb/Fe₃O₄@SiO₂/ITO) electrode was fabricated to determine the concentration of H₂O₂. UV‐vis absorption spectra, fourier transform infrared (FT‐IR) spectroscopy, cyclic voltammetry (CV) and high‐resolution transmission electron microscopy (HRTEM) were used to characterize the bioconjunction of Fe₃O₄@SiO₂ with Hb. Experimental results demonstrate that the immobilized Hb on the Fe₃O₄@SiO₂ matrix retained its native structure well. In addition, Fe₃O₄@SiO₂ nanoparticles (NPs) are very effective in facilitating electron transfer of the immobilized enzyme, which can be attributed to the unique nanostructure and larger surface area of the Fe₃O₄@SiO₂ NPs. The biosensor displayed good performance for the detection of H₂O₂ with a wide linear range from 2.03×10^?6 to 4.05×10^?3 mol/L and a detection limit of 0.32 µmol/L. The resulting biosensor exhibited fast amperometric response, good stability, reproducibility, and selectivity to H₂O₂.     

Three‐Dimensional Nitrogen‐Doped Reduced Graphene Oxide–Carbon Nanotubes Architecture Supporting Ultrafine Palladium Nanoparticles for Highly Efficient Methanol Electrooxidation

A three‐dimensional (3D) nitrogen‐doped reduced graphene oxide (rGO)–carbon nanotubes (CNTs) architecture supporting ultrafine Pd nanoparticles is prepared and used as a highly efficient electrocatalyst. Graphene oxide (GO) is first used as a surfactant to disperse pristine CNTs for electrochemical preparation of 3D rGO@CNTs, and subsequently one‐step electrodeposition of the stable colloidal GO–CNTs solution containing Na₂PdCl₄ affords rGO@CNTs‐supported Pd nanoparticles. Further thermal treatment of the Pd/rGO@CNTs hybrid with ammonia achieves not only in situ nitrogen‐doping of the rGO@CNTs support but also extraordinary size decrease of the Pd nanoparticles to below 2.0 nm. The resulting catalyst is characterized by scanning and transmission electron microscopy, X‐ray diffraction, Raman spectroscopy, and X‐ray photoelectron spectroscopy. Catalyst performance for the methanol oxidation reaction is tested through cyclic voltammetry and chronoamperometry techniques, which shows exceedingly high mass activity and superior durability.     

Magnetic solid‐phase extraction of brominated flame retardants from environmental waters with graphene‐doped Fe3O4 nanocomposites

Graphene‐doped Fe₃O₄ nanocomposites were prepared by a solvothermal reaction of an iron source with graphene. The nanocomposites were characterized by transmission electron microscopy, atomic force microscopy, X‐ray diffraction, superconducting quantum interference, Raman spectroscopy, Fourier transform infrared spectroscopy, and X‐ray photoelectron spectroscopy. This nanomaterial has been used as a magnetic solid‐phase extraction sorbent to extract trace brominated flame retardants from environmental waters. Various extraction parameters were optimized including dosage and reusability of the nanocomposites, and pH of sample matrix. The reliability of the magnetic solid‐phase extraction protocol based on graphene‐doped Fe₃O₄ nanocomposites was evaluated by investigating the recoveries of 2,4,6‐tribromophenol, tetrabromobisphenol A, 4‐bromodiphenyl ether, and 4,4?‐dibromodiphenyl ether in water samples. Good recoveries (85.0–105.0%) were achieved with the relative standard deviation ranging from 1.1–7.1%. Moreover, it is speculated from characterization and magnetic solid‐phase extraction experiment that there is not only π–π stacking but also possible hydrophobic interaction between the graphene‐doped Fe₃O₄ nanocomposites and analytes.