Plant‐supported silver nanoparticles: Efficient,economically viable and easily recoverable catalyst for the reduction of organic pollutants

Ginger rhizome powder was used for the synthesis of supported metallic nanoparticle catalysts. A simple and novel adsorption method was used for the synthesis of silver nanoparticles loaded on ginger powder (Ag/GP), copper on ginger powder (Cu/GP) and nickel on ginger powder (Ni/GP). Among these, Ag/GP showed selective reduction of methyl orange and was used for further reactions. The prepared nanomaterials were characterized through X‐ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, fourier transform infrared spectroscopy and energy‐dispersive X‐ray spectroscopy. The prepared Ag/GP catalyst was employed in the catalytic reduction of 4‐nitrophenol (4‐NP), 2‐nitrophenol (2‐NP), rhodamine B, methyl red and congo red. Ag/GP showed excellent catalytic reduction activity, the rate constants being 1.26 × 10^?3 and 2.38 × 10^?3 s^?1 for 2‐NP and 4‐NP, respectively. The turnover frequency reached 1.06 min^?1 for 2‐NP and 1.16 min^?1 for 4‐NP when using the Ag/GP catalyst. The prepared Ag/GP catalyst demonstrated outstanding activity for the degradation of a mixed solution of dyes. Also, stability and reusability of the prepared catalyst were investigated, which showed outstanding reusability up to five times and was stable up to five days.     

Synthesis and investigation of dual pH‐ and temperature‐responsive behaviour of poly[2‐(dimethylamino)ethyl methacrylate]‐grafted gold nanoparticles

Gold nanoparticles (AuNPs) were synthesized by reduction of chloroauric acid (HAuCl₄) aqueous solution with hydrazine monohydrate. The AuNPs were immediately treated with cysteamine to obtain amine‐functionalized nanoparticles (Au‐NH₂). The reaction of Au‐NH₂ with epichlorohydrin and subsequent treatment with sodium hydroxide gave epoxidized AuNPs (Au‐EP). Then, thiol‐capped AuNPs (Au‐SH) were synthesized by reaction of Au‐EP with cysteamine. A ‘grafting to’ approach was utilized to graft bromine‐terminated poly(N ,N ′‐dimethylaminoethyl methacrylate), synthesized via aqueous atom transfer radical polymerization, with various molecular weights (6280, 25 800, 64 200 and 87 600 g mol⁻¹) onto Au‐SH to obtain Au‐P1, Au‐P2, Au‐P3 and Au‐P4 samples, respectively. All samples were exposed to temperature and pH variations, and Z‐average diameter was monitored using dynamic light scattering. According to the results, polymer‐grafted nanoparticles collapsed at lower temperatures with increasing solution pH for all molecular weight ranges due to deprotonation of tertiary amine groups. However, higher molecular weight polymers were more sensitive to pH variation especially in alkaline media. Also, a high degree of agglomeration was observed for Au‐P4 nanoparticles in alkaline media on increasing the temperature to 55 and 65 °C.     

Green synthesis of reduced graphene oxide/Fe3O4/Ag ternary nanohybrid and its application as magnetically recoverable catalyst in the reduction of 4‐nitrophenol

Materials having both magnetic and catalytic properties have shown great potential for practical applications. Here, a reduced graphene oxide/iron oxide/silver nanohybrid (rGO/Fe₃O₄/Ag NH) ternary material was prepared by green synthesis of Ag on pre‐synthesized rGO/Fe₃O₄. The as‐prepared rGO/Fe₃O₄/Ag NH was characterized using Fourier transform infrared spectroscopy, X‐ray diffractometry, Raman spectroscopy, vibrating sample magnetometry, transmission electron microscopy and energy‐dispersive X‐ray spectroscopy. rGO sheets were covered with Fe₃O₄ (8–16 nm) and Ag (18–40 nm) nanoparticles at high densities. The mass percentages were 13.47% (rGO), 62.52% (Fe₃O₄) and 24.01% (Ag). rGO/Fe₃O₄/Ag NH exhibited superparamagnetic behavior with high saturated magnetization (29 emu g⁻¹ at 12 kOe), and efficiently catalyzed the reduction of 4‐nitrophenol (4‐NP) with a rate constant of 0.37 min⁻¹, comparable to those of Ag‐based nanocatalysts. The half‐life of 4‐NP in the presence of rGO/Fe₃O₄/Ag NH was ca 1.86 min. rGO/Fe₃O₄/Ag NH could be magnetically collected and reused, and retained a high conversion efficiency of 94.4% after the fourth cycle. rGO/Fe₃O₄/Ag NH could potentially be used as a magnetically recoverable catalyst in the reduction of 4‐NP and environmental remediation.     

AgPt nanoparticles supported on magnetic graphene oxide nanosheets for catalytic reduction of 4‐nitrophenol: Studies of kinetics and mechanism

Ag_x Pt_100−x (x  = 0, 25, 50, 75 and 100) nanoparticles were grown on the surface of magnetic graphene oxide nanosheets (Fe₃O₄@GO) for the first time. The as‐prepared nanocomposites were characterized using various techniques such as Fourier transform infrared spectroscopy, powder X‐ray diffraction, field emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, transmission electron microscopy, Brunauer–Emmett–Teller surface area analysis, vibrating sample magnetometry and thermogravimetric analysis. The Fe₃O₄@GO‐Ag_x Pt_100−x catalysts were applied in the reduction of 4‐nitrophenol (4‐NP) to 4‐aminophenol using sodium borohydride (NaBH₄). The synthesized nanocomposites exhibited excellent catalytic performance in the reduction of 4‐NP with high recyclability for five consecutive runs. The Fe₃O₄@GO‐Ag₇₅Pt₂₅ nanocomposite exhibited the best catalytic activity with a rate constant as high as 140.6 × 10⁻³ s⁻¹. The obtained kinetic data were modelled with the Langmuir–Hinshelwood equation. The energy of activation and thermodynamic parameters including enthalpy, entropy of activation and activation Gibbs free energy were calculated.     

In situ polymerization and reduction to fabricate gold nanoparticle‐incorporated polyaniline as supercapacitor electrode materials

Nanocomposites of gold nanoparticles and polyaniline are synthesized by using HAuCl₄ and ammonium peroxydisulfate as the co‐oxidant involving in situ polymerization of aniline and in situ reduction of HAuCl₄. Through these in situ methods, the synthesized Au nanoparticles of ca. 20 nm embedded tightly and dispersed uniformly in polyaniline backbone. With the Au content in composite increasing from 4.20 to 24.72 wt.%, the specific capacitance of the materials first increased from 334 to 392 F g⁻¹ and then decreased to 298 F g⁻¹. Based on the real content of PANI in composite material, the highest specific capacitance is calculated to be 485 F g⁻¹ at the Au amount of 19.15 wt.%, which remains 55.6% after 5000 cycles at the current density of 2 A g⁻¹. Finally, the asymmetric supercapacitor of AuNP/PANI||AC and the symmetric supercapacitor of AuNP/PANI||AuNP/PANI are assembled. The asymmetric supercapacitor device shows a better electrochemical performance, which delivers the maximum energy density of 7.71 Wh kg⁻¹ with power density of 125 W kg⁻¹ and maximum power density of 2500 W kg⁻¹ with the energy density of 5.35 Wh kg⁻¹.     

Preparation and Characterization of Polymer‐Protected Pt@Pt/Au Core‐Shell Nanoparticles

Poly(N‐vinyl‐2‐pyrolidone) protected Pt‐core bimetallic Pt/Au‐shell (Pt@Pt/Au) nanoparticles were prepared by multi‐step reduction of HAuCl₄ and H₂PtCl₆ alternately by hydrogen adsorbed on platinum atom. Transmission electronic microscopy (TEM) and x‐ray diffraction (XRD) were used to characterize Pt@Pt/Au nanoparticles. The structure of the shell of the nanoparticles seems to be the Au‐Pt solid solution.     

Gold nanoparticles stabilized by modified halloysite nanotubes for catalytic applications

A highly sustainable prototype of a flow system based on gold nanoparticles (4.2 nm) supported on thiol‐functionalized halloysite nanotubes (HNTs) was developed for catalytic applications. The catalytic performances were evaluated using the reduction of 4‐nitrophenol to 4‐aminophenol as a model system. Under the best experimental conditions (0.0001 mol%, 1.97 × 10^?8 mg of Au nanoparticles), an impressive apparent turnover frequency value up to 2 204 530 h^?1 was achieved and the halloysite‐based catalyst showed full recyclability even after ten cycles. The high catalytic activity confirms the importance of the use of HNTs as support for Au nanoparticles that can exert a synergistic effect both as medium for transfer of electrons from borohydride ions to 4‐nitrophenol and by modulating interfacial electron transfer dynamics. With the application of flow technology, the obtained heterogeneous HNT@Au catalyst was fully recovered and reused for at least one month.     

Phosphomolybdate-doped-poly(3,4-ethylenedioxythiophene) coated gold nanoparticles: Synthesis,characterization and electrocatalytic reduction of bromate

Phosphomolybdate, H₃PMo₁₂O₄₀, (PMo₁₂)-doped-poly(3,4-ethylenedioxythiophene) (PEDOT) coated gold nanoparticles have been synthesized in aqueous solution by reduction of AuCl₄⁻ using hydroxymethyl EDOT as a reducing agent in the presence of polystyrene sulfonate and PMo₁₂. The resulting PMo₁₂-doped-PEDOT stabilized Au nanoparticles are water soluble and have been characterized by UV–visible spectroscopy, scanning electron microscopy and electrochemistry. Glassy carbon electrodes modified with these Au nanoparticles show excellent stability and catalytic activity towards the reduction of bromate in an aqueous electrolyte solution containing 10 mM H₂SO₄ and 0.1 M Na₂SO₄.     

Nano NiO/AlMCM‐41, a green synergistic,highly efficient and recyclable catalyst for the reduction of nitrophenols

Highly ordered mesoporous molecular sieves AlMCM‐41 and a new NiO/AlMCM‐41 nanocomposite were synthesized using a sol–gel method. Fourier transform infrared (FT‐IR) spectroscopy, X‐ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X‐ray spectroscopy (EDX), and N₂ adsorption desorption analyses were used to examine the structure, morphology, size and phase composition of the synthesized NiO/AlMCM‐41 nanocomposites. AlMCM‐41 embedded with NiO nanoparticles was subsequently prepared using different nickel loadings in a direct synthetic route. The results show the successful deposition of NiO nanoparticles onto the framework of AlMCM‐41. AlMCM‐41 provides enormous benefits such as environmentally safe, economic viability and porosity when used as support for NiO nanoparticles. The excellent catalytic activities of AlMCM‐41 and NiO/AlMCM‐41 were investigated for the reduction of nitrophenols (4‐NP, 2‐NP) to aminophenols (4‐AP, 2‐AP) in water at ambient temperature. The best observed performance of reduction of NP with 100% conversion into analogous amino derivatives occurred within 6 min with an estimated rate constant of 0.46 min^?1. The efficiency of reduction was observed to increase as a function of NiO enrichment. The NiO/AlMCM‐41 nanocomposite could be recycled and reused up to five times without noticeable change in its structure and activity. These properties make NiO/AlMCM‐41 nanocomposite an ideal platform to study various heterogeneous catalytic processes which can have application in purification, catalysis, sensing devices, and green chemistry.     

In situ synthesis of silver nanoparticles on densely amine‐functionalized polystyrene: Highly active nanocomposite catalyst for the reduction of methylene blue

In this contribution, polystyrene (PS) bearing nitrogen‐rich ligands as chelation moieties for both Ag⁺ ions and Ag⁽⁰⁾ nanoparticles was prepared through successive chemical modifications of native PS including nitration (treatment with HNO₃/H₂SO₄), reductive amination (treatment with SnCl₂/HCl), Michael addition of methyl acrylate, and grafting of ethyelenediamine. The as‐synthesized PS derivative was further used to support silver nanoparticles through initial chelation of the silver nanoparticle ions precursor and subsequent chemical in situ reduction with sodium borohydride. Chemical structure of the PS derivatives was confirmed after each synthesis step by using complementary characterization methods including infrared and energy‐dispersive X‐ray spectroscopies, elemental analysis, X‐ray diffraction, thermogravimetric analysis, and scanning electron microscopy. The catalytic activity of the PS‐EAD/AgNP nanocomposite was demonstrated using the reduction of methylene blue to leucomethylene blue, as a model reaction. The reaction was monitored by UV‐vis spectrophotometry and achieved with an excess of sodium borohydride allowing for a pseudo‐first‐order analysis of the kinetic reaction parameters. Quantitative reduction of the methylene blue was obtained upon successive catalytic cycles with a rate constant value of 0.4016 minute^?1.     

Ultra‐low‐loading palladium nanoparticles stabilized on nanocrystalline Polyaniline (Pd@PANI): A efficient,green, and recyclable catalyst for the reduction of nitroarenes

Ultra‐low‐loading Pd@PANI nanocomposites (0.048 w.t% Pd) were synthesized via a method that combined interfacial polymerization and in situ composite with camphor sulfonic acid ((+)‐CSA) as a dopant. Transmission electron microscopy (TEM), X‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectra, and X‐ray photoelectron spectroscopy (XPS) were performed to characterize the structures. It can be used as an efficient catalyst for the reduction of nitroarenes in aqueous solution by using a smaller amount of NaBH₄ (2.5 equiv.) at room temperature with high activity (TON = 3.4 × 10³), good stability (cycled eight times), as well as wide applicability (27 substrates). The catalyst also showed a marvelous activity in the gram‐level reaction (yield = 92%). UV–Visible spectrophotometry was used to investigate the reaction kinetics for the reduction of 4‐nitrophenol to 4‐aminophenol, and the results reconfirmed the excellent performance of the catalyst. The unique properties and superior performance of the prepared ultra‐low‐loading Pd@PANI nanocomposites lead it be an attractive alternative catalyst for conventional organic catalytic applications.     

Bimetallic Au–Ni Nanoparticles Embedded in SiO2 Nanospheres: Synergetic Catalysis in Hydrolytic Dehydrogenation of Ammonia Borane

Gold–nickel nanoparticles (NPs) of 3–4 nm diameter embedded in silica nanospheres of around 15 nm have been prepared by using [Au(en)₂Cl₃] and [Ni(NH₃)₆Cl₂] as precursors in a NP‐5/cyclohexane reversed‐micelle system, and by in situ reduction in an aqueous solution of NaBH₄/NH₃BH₃. Compared with monometallic Au@SiO₂ and Ni@SiO₂, the as‐synthesized Au–Ni@SiO₂ catalyst shows higher catalytic activity and better durability in the hydrolysis of ammonia borane, generating a nearly stoichiometric amount of hydrogen. During the generation of H₂, the synergy effect between gold and nickel is apparent: The nickel species stabilizes the gold NPs and the existence of gold helps to improve the catalytic activity and durability of the nickel NPs.     

Colorimetric Sensing of Adenosine Based on Aptamer Binding Inducing Gold Nanoparticle Aggregation

A simple and rapid colorimetric approach for the determination of adenosine has been developed via target inducing aptamer structure switching, thus leading to Au colloidal solution aggregation. In the absence of the analytes, the aptamer/gold nanoparticle (Au NP) solution remained well dispersed under a given high ionic strength condition in that the random‐coil aptamer was readily wrapped on the surface of the Au NPs, which resulted in the enhancement of the repulsive force between the nanoparticles due to the high negative charge density of DNA molecules. While in the presence of adenosine, target‐aptamer complexes were formed and the conformation of the aptamer was changed to a folded structure which disfavored its adsorption on the Au NP surface, thus leading to the reduction of the negative charge density on each Au NP and then the reduced degree of electrostatic repulsion between Au nanoparticles. As a result, the aggregation of the Au colloidal solution occurred. The changes of the absorption spectrum could be easily monitored by a UV‐Vis spectrophotometer. A linear correlation exists between the ratio of the absorbance of the system at 522 to 700 nm (A_{522 nm}/A_{700 nm}) and the concentration of adenosine between 100 nmol·L^?1 and 10 µmol·L^?1, with a detection limit of 51.5 nmol·L^?1.     

Potentiometric Study of the Growth of a Single Au Nanoparticle

A single nanoparticle (NP) attached to a nanoelectrode is a very useful system in understanding the relationship between the size of nanoparticles and their electrochemical properties. In this study, a single Au NP was spontaneously formed on a Pt nanoelectrode. The potential measured on such a system can be employed to study the effect of size of an Au nanoparticle on the Nernst potential of the reaction, AuCl₄⁻ +3e → Au(s) +4Cl⁻. Moreover, the nucleation period and the growth period can be distinguished from the potential graph, and the nucleation rate of the spontaneously formed Au NP can be evaluated.     

Embedment of Well Dispersed Nickel Nanoparticles in Sulfonate and Benzimidazole Functionalized Poly (Arylene Ether Ketone) Film for the Electrocatalytic Oxidation of Glucose

Stable and well dispersed nickel nanoparticles (NiNPs) were fabricated and embedded in a novel polymer sulfonate and benzimidazole functionalized poly (arylene ether ketone) (S‐BI‐PAEK) film. After drop‐casting the mixed solution of S‐BI‐PAEK and NiSO₄ on glassy carbon electrode (GCE) surface, the uniformly distributed NiNPs were formed and stably embedded in S‐BI‐PAEK film by in‐situ electrochemical reduction method. The embedment and well dispersity of NiNPs in S‐BI‐PAEK film was probably attributed to the strong chelation of sulfonate and benzimidazole functional groups contained in S‐BI‐PAEK toward Ni²⁺ ions, as well as the transferability of Ni²⁺ ions in S‐BI‐PAEK film. The NiNPs/S‐BI‐PAEK composite film was characterized by scanning electron microscopy (SEM), energy dispersive X‐ray spectroscopy (EDS), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). It exhibited good electrocatalytic activity toward glucose oxidation in 0.1 mol L⁻¹ NaOH solution with high stability. The NiNPs/S‐BI‐PAEK/GCE showed a fast amperometric response with a wide linear range from 1 μM to 4 mM and a low detection limit of 200 nmol L⁻¹ (S/N=3) for the determination of glucose by amperometry at a potential of 0.55 V. Finally it was successfully employed to determine glucose in human serum. Therefore, the novel fabrication method of nickel nanoparticles was promising for the future development of non‐enzymatic glucose sensor.     

Synthesis of Tetraoxygenated Terephthalates via a Dichloroquinone Route: Characterization of Cross‐Conjugated Liebermann Betaine Intermediates

Cross‐conjugated quinoid betaines 4 (2,5‐bis(alkoxycarbonyl)‐3,6‐dioxo‐4‐(1‐pyridinium‐1‐yl)cyclohexa‐1,4‐dien‐1‐olates; Liebermann betaines) were synthesized from 2,5‐dichloro‐3,6‐dioxocyclohexa‐1,4‐diene‐1,4‐dicarboxylates ( 2 ) and pyridines in acetone containing H₂O. Their structure was secured by NMR spectroscopy and by X‐ray diffraction analysis of 4f (alkoxy = EtO, pyridine = 4‐Me₂N–C₅H₄N). Betaines 4 show comparatively high reactivity towards nucleophiles as a consequence of their cross‐conjugated character. Betaine 4a and hydroxy‐3,4‐methylenedioxybenzene (sesamol) condense to give a pyridinium quinolate salt 14 which has a bifurcate H‐bond from a pyridinium N⁺–H donor to both carbonyl (C=O) and olate (C–O⁻) acceptors in the solid state. Betaine 4b hydrolyzes in aqueous solution to give diethyl 2,5‐dihydroxy‐3,6‐dioxocyclohexa‐1,4‐diene‐1,4‐dicarboxylate ( 11 ) as a pyridinium salt, or as polymeric zinc(II) complex of the dianion of 11 in the presence of ZnCl₂. Dihydroxyquinone 11 was analytically differentiated from its independently prepared hydroquinone form, diethyl 2,3,5,6‐tetrahydroxyterephthalate ( 12 ), by NMR analysis in solution and X‐ray crystal structure determination of both compounds.     

Catalytic reduction of 4‐nitrophenol using silver nanoparticles‐engineered poly(N‐isopropylacrylamide‐co‐acrylamide) hybrid microgels

Nearly monodisperse poly(N ‐isopropylacrylamide‐co ‐acrylamide) [P(NIPAM‐co‐AAm)] microgels were synthesized using precipitation polymerization in aqueous medium. These microgels were used as microreactors to fabricate silver nanoparticles by chemical reduction of silver ions inside the polymer network. The pure and hybrid microgels were characterized using Fourier transform infrared and UV–visible spectroscopies, dynamic light scattering, X‐ray diffraction, thermogravimetric analysis, differential scanning calorimetry and transmission electron microscopy. Results revealed that spherical silver nanoparticles having diameter of 10–20 nm were successfully fabricated in the poly(N ‐isopropylacrylamide‐co ‐acrylamide) microgels with hydrodynamic diameter of 250 ± 50 nm. The uniformly loaded silver nanoparticles were found to be stable for long time due to donor–acceptor interaction between amide groups of polymer network and silver nanoparticles. Catalytic activity of the hybrid system was tested by choosing the catalytic reduction of 4‐nitrophenol as a model reaction under various conditions of catalyst dose and concentration of NaBH₄ at room temperature in aqueous medium to explore the catalytic process. The progress of the reaction was monitored using UV–visible spectrophotometry. The pseudo first‐order kinetic model was employed to evaluate the apparent rate constant of the reaction. It was found that the apparent rate constant increased with increasing catalyst dose due to an increase of surface area as a result of an increase in the number of nanoparticles.     

Facile preparation of Au nanoparticle-embedded polydopamine hollow microcapsule and its catalytic activity for the reduction of methylene blue

Abstract

Development of novel supported catalysts with high activity and stability is still a challenge. In this study, the Au-polydopamine (Au-PDA) hollow microcapsules with Au nanoparticles embedded into the PDA microcapsule shell have been synthesized through a simple template-induced covalent assembly method, where polystyrene (PS) nanospheres were used as templates to form core/shell structured PS/Au-PDA composites, followed by core removal through tetrahydrofuran etching. Their morphology and composition were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared spectra (FT-IR), UV-Vis spectrophotometer and X-ray diffraction (XRD), respectively. Results showed that the Au-PDA microcapsules possessed well-fined hollow structure and uniform sizes with inner diameter of about 385?nm, shell thickness of about 30?nm, and Au nanoparticles with diameter of about 17?nm incorporated. The catalytic performance of Au-PDA hollow microcapsules was evaluated through the reduction of methylene blue (MB) dye with NaBH₄ as a reducing agent. Compared to PDA/Au composites with Au nanoparticles loaded on the surface of PDA microspheres, as-prepared Au-PDA hollow microcapsules show good stability and recyclability in the catalytic experiments as the Au nanoparticles were firmly wrapped in PDA matrix, which makes the Au-PDA hollow microcapsules a practicable catalyst candidate for advanced catalytic systems.     

Synthesis, Structure and Growth Mechanism of Size and Shape Tunable Au/Ag Bimetallic Nanoparticles

By simply adding ascorbic acid in advance of AgNO₃, the size and shape controllable Au/Ag bimetallic nanoparticles (NP) were prepared in the traditional Au growth solution free of seed at room temperature. The size distribution of NP is well uniform with ca. 10%–15% standard deviation in diameter. By changing CTAB concentration, the size and shape of NPs are tunable. After researching the surface‐enhanced Raman spectroscopy (SERS) behavior of the prepared NPs, an enhancement factor varied from 4.3×10⁴ to 1.1×10⁵ was obtained for the NP centered at ca. (64±8) nm. Electrochemical cyclic voltammetric results revealed that the so formed nanoparticles were Au riched Au/Ag bimetallic NP, and this formation might be due to the disproportionation reaction of Au⁺ prompted by Ag⁺ and the under potential deposition process of Ag⁺ on Au.     

Green synthesis of Fe3O4@SiO2‐Ag magnetic nanocatalyst using safflower extract and its application as recoverable catalyst for reduction of dye pollutants in water

This paper reports the green and in situ preparation of Fe₃O₄@SiO₂‐Ag magnetic nanocatalyst synthesized using safflower (Carthamus tinctorius L.) flower extract without the addition of any stabilizers or surfactants. The catalytic performance of the resulting nanocatalyst was examined for the reduction of 4‐nitrophenol (4‐NP), methylene blue (MB) and methyl orange (MO) in an environment‐friendly medium at room temperature. The main factors such as pH, temperature and amount of catalyst influencing the nanocatalyst performance were studied. The apparent rate constants for 4‐NP, MO and MB reduction were calculated, being 0.756 min^?1, 0.064 s^?1 and 0.09 s^?1, respectively. The catalyst was recovered using an external magnet and reused several times with negligible loss of catalytic activity. The as‐synthesized nanoparticles were characterized using powder X‐ray diffraction, transmission electron microscopy, UV–visible, Fourier transform infrared and inductively coupled plasma atomic emission spectroscopies, dynamic light scattering and vibrating sample magnetometry.