Traditional Co-precipitation Research Articles

Meticulous guard: The role of Al/F doping in improving the electrochemical performance of high-voltage spinel cathode

Spinel LiNi0.5Mn1.5O4, which is considered as one of the most attractive candidates for high energy density battery due to its high voltage platform over 4.7 V, suffers from the side reactions with electrolyte, strong oxidability of Ni4+ and therefore the complicated and frangible Solid Electrolyte Interfaces (SEI) layer that hinders the practical application of LiNi0.5Mn1.5O4. In this work, traditional co-precipitation method is applied and improved by anion and cation doping method to construct superior interface on the surface of LiNi0.5Mn1.5O4 to suppress side reactions especially at high temperature. Detailed properties including structure, morphology and electrochemical performance of pristine sample, single-doped and co-doped samples are probed. Physical characterizations reveal that the co-doped sample with regular octahedron has a moderate grain size and specific surface area between Al and F single doping, and holds the advantages of rate performance and capacity retention causing by Al doping and better stability under high temperature constructing by F. It exhibits the best capacity retention of 92% after 200 cycles under 55 °C, which is higher than that of the pristine sample (87%). Analysis of the electrode after cycling shows that doping reduces the thickness of the electrode interface film and the content of inorganic substances such as LiF to improve the interface characteristics and the high temperature cycling performance. This work has certain significance for the commercial application of LiNi0.5Mn1.5O4.

Controlled Dy-doping to nickel-rich cathode materials in high temperature aerosol synthesis

Layered nickel-rich materials are promising next-generation cathode materials for lithium ion batteries due to their high capacity and low cost. However, the poor thermal stability and longtime cycling performance hinders the commercial applications of high nickel materials. Doping with heteroatoms has been an effective approach for improving electrochemical performance of cathode materials. Controlling doping concentration and geometrical distribution is desired for optimal electrochemical performance, but it is challenging in traditional co-precipitation methods. In this work, controlled dysprosium (Dy) doping to NCM811 was studied in an aerosol synthesis method by controlling the precursor concentrations and heating parameters. The obtained materials were characterized by SEM, XRD, and XPS, and their electrochemical properties and thermal stability were evaluated. By controlling the doping concentration (1.5%), Dy-doped NCM811 was improved simultaneously in long-term cycling and high-rate performance. The thermal-chemical stability of the Dy-doped cathode materials was examined in a microflow reactor with a mass spectrometer. The results showed that Dy-doping shifted the O2 onset temperature to a higher temperature and reduced O2 release by 80%, thus dramatically increasing the thermal-chemical stability and improving the fire safety of cathode materials. Since high temperature aerosol synthesis is a low-cost and scalable method, the findings in this work have broad implications for commercial synthesis of novel materials with controlled doping modification to achieve high electrochemical performance and safety in lithium ion batteries.

Superior performance of Cu/TiO2 catalyst prepared by ice melting method for low-temperature selective catalytic reduction of NOx by NH3

A series of Cu/TiO2 catalysts was successfully synthesized by ice melting method for the first time, and their performance for the selective catalytic reduction of NOx with NH3 was evaluated. The catalyst with Cu/Ti molar ratio of 0.005 exhibited excellent catalytic performance at low temperature. Compared with the traditional co-precipitation method (Cu0.005Ti-Con), the NOx conversion (at 285 °C) and N2 selectivity (at 240 °C) of Cu/TiO2 synthesized by ice melting (named as Cu0.005Ti-Ice) increased by 30 % and 10 %, respectively. Characterization results revealed that Cu0.005Ti-Ice exhibited outstanding physicochemical properties, including smaller grain size of particles, the well dispersion and high surface atomic concentration of Cu species, enrichment of Cu2+ species (34.54 %) and chemical absorbed oxygen species (19.96 %), and excellent redox capacity and acidity. These conditions provided the CuTi-Ice catalysts with enhanced deNOx performance at low temperature. Additionally, the inhibition of the non-selective catalytic reduction and NH3 catalytic oxidation on Cu0.005Ti-Ice catalysts reduced N2O and NO2 concentration, resulting in outstanding SCR activity at low temperature.

A simple and novel effective strategy using mechanical treatment to improve the oxygen uptake/release rate of YBaCo4O7+δ for thermochemical cycles

In recent years, oxygen storage materials (OSMs) have been widely used in many fields. It would be particularly important for researchers to design high-oxygen-uptake/release-rate materials. In this study, various synthesis processes were used to successfully synthesize YBaCo4O7+δ and comprehensively investigate their potential applications. Compared with traditional solid-state reaction method and co-precipitation method, the results demonstrated that the utilization of mechanical ball milling treatment on co-precipitated precursors could lead to samples with reversible oxygen uptake/release under an oxidative atmosphere at low temperatures. The resultant materials exhibited fast oxygen absorption/desorption rate that could uptake/release oxygen directly to the equilibrium state within 9 min and 20 min, respectively. The mechanochemically ball-milled sample possessed outstanding oxygen storage performance, which could be attributed to their small particle size, the active outer surface of particles, large specific surface area, and relatively low activation energy. Moreover, the ball-milled sample also exhibited excellent cycling stability during relatively short time spacing. TG results also demonstrated that the ball-milled samples could reversibly uptake/release 2.90 wt.% of excess oxygen (while only 0.70 wt.% for solid-state samples) by adjusting the ambient temperature under pure O2 atmosphere, which would make them promising candidates in various applications. This research demonstrated that mechanical treatment could be an effective strategy to tune the properties and oxygen storage capacity(OSC) performances of YBaCo4O7+δ.

Oxidative Dehydrogenation of Propane over Ni–Al Mixed Oxides: Effect of the Preparation Methods on the Activity of Surface Ni(II) Species

4Ni–Al layered double hydroxide (LDH) precursors were prepared by the following three methods: constant pH coprecipitation, variable pH coprecipitation and urea hydrolysis. The 4Ni–Al mixed metal oxide (MMO) catalysts were obtained by the calcination of LDH precursors at 600 °C, and their catalytic performances in ODHP from 350 to 550 °C were tested. The 4Ni–Al MMO from the urea hydrolysis method showed a higher and more stable propylene selectivity of ca. 40% with propylene yield of ca.11% at 500 °C, and that from the constant pH coprecipitation method was followed, while oxidative cracking of propane occurred on the 4Ni–Al MMO from the variable pH coprecipitation method. It is considered to be closely related to the dispersion and stability of the surface Ni(II) species through comprehensive analysis of XRD, N2-adsorption-desorption, TEM, XPS, H2-TPR and In-situ electrical conductivity. The urea hydrolysis method with a low salt concentration, leading to an excellent stability of the surface Ni(II) species at high reaction temperature, should be selected to prepare Ni–Al MMO catalysts for ODHP instead of the traditional variable pH coprecipitation method with a high salt concentration.

Novel synthetic route to Ce-Cu-W-O microspheres for efficient catalytic oxidation of vinyl chloride emissions

The solubility of ammonium tungstate in a special hydrothermal condition is exploited to synthesize uniform microspheres of Ce-Cu-W-O oxides. Compared to their W-undoped counterparts, they possess more Ce3+ and oxygen vacancies, thereby promoting oxygen mobility. The formed rich WO3 surface can effectively provide acid sites, which is helpful for adsorption of vinyl chloride and interrupting the C–Cl bond. In addition, the presence of WO3 induces the formation of finer CuO nanoparticles with respect to the traditional coprecipitation method, thereby resulting in a better reducibility. Benefiting from both the enhanced acidity and reducibility, the Ce-Cu-W-O microspheres deliver excellent low-temperature vinyl chloride oxidation activity (a reaction rate of 2.01 × 10−7 mol/(gcat·s) at 250 °C) and high HCl selectivity. Moreover, subtle deactivation occurs after the three cycling activity tests, and a stable vinyl chloride conversion as well as mineralization are observed during the 72-h durability test at 300 °C, which demonstrates good thermal stability. Our strategy can provide new insights into the design and synthesis of metal oxides for catalytic oxidation of chlorinated volatile organic compounds.

Three-Dimensional Mesoporous Ni-CeO2 Catalysts with Ni Embedded in the Pore Walls for CO2 Methanation

Mesoporous Ni-based catalysts with Ni confined in nanochannels are widely used in CO2 methanation. However, when Ni loadings are high, the nanochannels are easily blocked by nickel particles, which reduces the catalytic performance. In this work, three-dimensional mesoporous Ni-CeO2-CSC catalysts with high Ni loadings (20−80 wt %) were prepared using a colloidal solution combustion method, and characterized by nitrogen adsorption–desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM) and H2 temperature programmed reduction (H2-TPR). Among the catalysts with different Ni loadings, the 50% Ni-CeO2-CSC with 50 wt % Ni loading exhibited the best catalytic performance in CO2 methanation. Furthermore, the 50% Ni-CeO2-CSC catalyst was stable for 50 h at 300° and 350 °C in CO2 methanation. The characterization results illustrate that the 50% Ni-CeO2-CSC catalyst has Ni particles smaller than 5 nm embedded in the pore walls, and the Ni particles interact with CeO2. On the contrary, the 50% Ni-CeO2-CP catalyst, prepared using the traditional coprecipitation method, is less active and selective for CO2 methanation due to the larger size of the Ni and CeO2 particles. The special three-dimensional mesoporous embedded structure in the 50% Ni-CeO2-CSC can provide more metal–oxide interface and stabilize small Ni particles in pore walls, which makes the catalyst more active and stable in CO2 methanation.

ROS-Responsive Chitosan Coated Magnetic Iron Oxide Nanoparticles as Potential Vehicles for Targeted Drug Delivery in Cancer Therapy.

Background and ObjectiveCancer cells accumulate high concentrations of reactive oxygen species as a result of their faster and uninhibited metabolic activity. Cancer chemotherapeutic agents release an excess of severe adverse reactions as a result of targeting normal cells. This demands an improvement in targeted drug-delivery systems to selectively discharge anticancer drugs in the vicinity of such highly metabolically and mitotically active cells.Materials and MethodsHere, magnetic nanoparticles were synthesized by a traditional co-precipitation technique. Fe3O4@OA-CS-5-FLU-NPs were synthesized by an easy and rapid in situ loading method. The proposed Fe3O4@OA-CS-5-FLU-NPs were productively prepared as well as characterized by various spectroscopic and microscopic studies.ResultsThe targeted drug release profile of the Fe3O4@OA-CS-5-FLU-NPs was studied in the presence of ROS including H2O2 and pH induction. The released product, Fe3O4@OA-CS-5-FLU-NP, exhibited desirable levels of cytotoxicity and demonstrated morphological changes and inhibition of colony formation for A549 and HeLa S3 cancer cells. The IC50 values at 24 hours were 12.9 and 23 μg/mL, respectively.ConclusionIn summary, results from the MTT assay, fluorescence staining as well as colony formation assays, revealed that the Fe3O4@OA-CS-5-FLU-NPs were active and safe for anticancer biomedical applications. In summary, the present investigation provides a powerful nanostructured based system for improved cancer theranostics that should be further studied.

Highly-ordered microstructure and well performance of LiNi0.6Mn0.2Co0.2O2 cathode material via the continuous microfluidic synthesis

Ni-rich layered oxides are potential cathode candidate’s materials for Li-ion batteries due to their low cost and high energy density. However, it is difficult to reproducibly prepare uniformly distributed element and well-controlled morphology of Ni-rich layered oxide particles. This study develops a continuous microfluidic reaction process to synthesize spherical carbonate precursors (Ni0.6Mn0.2Co0.2CO3). The as-synthesized LiNi0.6Co0.2Mn0.2O2 materials exhibit well-defined microsphere morphology, uniform particles size distribution, better thermal stability and homogeneous transition metal distribution, due to the excellent mixing, well mass and heat transfer rate during the microfluidic reaction. Moreover, the as-prepared LiNi0.6Co0.2Mn0.2O2 materials achieve higher initial capacity, excellent electrochemical reversibility and capacity retention than that of the samples prepared by traditional co-precipitation. Therefore, our results demonstrate that microfluidic reaction is a simple and effective synthesis technology for preparing Ni-rich layered cathode.

A novel microreaction strategy to fabricate superior hybrid zirconium and zinc oxides for methanol synthesis from CO2

The synergetic interaction of solid solutions plays important roles in the reaction efficiency of CO2 hydrogenation, which is used to produce methanol. The effects of material mixing, impregnation, traditional coprecipitation, and microreaction synthesis on the structural and catalytic properties of ZnO/t-ZrO2 hybrid oxides were investigated. Although the impregnation effect caused a certain electronic structural modulation at the Zn/Zr interface, the pore structure blocking effect and low number of oxygen vacancy defects leaded to a low catalytic reaction efficiency. The solid solution structure enhanced the Zn/Zr interfacial interaction and increased the electron binding energy. More importantly, many oxygen vacancy defects were formed, which promoted CO2 activation. However, the solid solution structure was more affected by the preparation method. The solid solution formed from the microreaction exhibited excellent catalytic activity, thermal stability and regeneration performance due to a more uniform solid solution structure and abundant oxygen vacancy defects. The CO2 conversion rate, methanol selectivity, and methanol space-time yield (STY) under the conditions of H2/CO2 = 3:1, 320 °C, 3 MPa, GHSV = 12,000 ml g−1 h−1 reached 9.2 %, 93.1 %, and 0.35 gMeOH h−1gcat−1, respectively.

Oriented Isomorphous Substitution: An Efficient and Alternative Route to Fabricate the Zn Rich Phase Pure (Cu1−x,Znx)2(OH)2CO3 Precursor Catalyst for Methanol Synthesis

AbstractA new methodology has been demonstrated for the synthesis of a series of phase pure (Cu1−x,Znx)2(OH)2CO3 precursors by isomorphous substitution of Zn2+ in the malachite structure. By following the present protocol, it was possible to synthesize the pure phase (Cu1−x,Znx)2(OH)2CO3 with substitution level as high as x=0.5, which is better than the maximum possible value achieved by coprecipitation method, i. e. x=0.31. The isomorphous substitution by Zn2+ leads to the change in the morphology of malachite crystals from flake‐like to regular needle‐like shape with high Zn dispersion. The activity of the calcined catalysts was increased by ∼1.5–1.7 fold for the hydrogenation of syngas to methanol as compared with those prepared from the traditional coprecipitation route. The synergy between Cu and ZnO was further demonstrated quantitatively by characterization of the catalysts treated with syngas at 250 °C.

Highly efficient copper-manganese oxide catalysts with abundant surface vacancies for low-temperature water-gas shift reaction

Efficient and low-cost water-gas shift (WGS) catalysts have aroused much attention for the purification of H2-rich syngas in the application of fuel cell. In this study, combustion of ethylene glycol and methanol (EGM), fractional precipitation (FP) and template growth (TG) methods have been utilized to synthesize copper-manganese oxide (CMO) catalysts. The prepared CMO catalysts are consisted of spinel Cu1.5Mn1.5O4 and Mn2O3 phases and exhibit porous, polyhedral nanoparticle and nanorod morphologies for EGM, FP and TG, respectively. The low-temperature WGS reaction activities of prepared catalysts follow the sequence: CMO-EGM > CMO-FP > CMO-TG, which are higher than that of CMO catalyst prepared by traditional co-precipitation method. Among them, CMO-EGM catalyst exhibits the highest reaction rate of 122.72 μmolCO gcat.−1 s−1 at 200 °C, which is much higher than that of commercial Cu/ZnO/Al2O3 (73.62 μmolCO gcat.−1 s−1). CO-TPSR and DRIFTS analysis reveal the superior activity of CMO-EGM is attributed to the larger amounts of active hydroxyl groups on the surface of catalysts, which correlate well with the high reducibility and abundant surface oxygen vacancies of CMO-EGM catalyst.

One-step preparation of homogeneous single crystal Li-rich cathode materials with encouraging electrochemical performance

The electrochemical properties and microstructure of Li-rich cathode materials Li1.2Mn0.54Co0.13Ni0.13O2 synthesized in one-step were studied. The sample (s-g) was composed of single crystal particles (1–2 μm) with regular and smooth surface, and the particle size distribution was concentrated. Compared with the sample (cop) prepared by traditional coprecipitation method, the discharge specific capacity of sample s-g increased from 79.9 mAh g−1 to 114.5 mAh g−1 at 10C. After 100 cycles at the rate of 0.1C and 0.2C, the capacity retention rates of sample s-g were 99.48% and 105.36%, while those of sample cop were 66.23% and 71.55%, respectively. Homogeneous single crystal structure and good grain size control greatly released the capacity potential of Li-rich cathode materials and solved the problem of poor rate performance and fast capacity decay.

Fabrication of a CuZn-based catalyst using a polyethylene glycol surfactant and supercritical drying

We employed PEG treatment and supercritical CO2 drying to improve the traditional co-precipitation method for fabrication of CuZn-based catalysts for alcohol-assisted low-temperature methanol synthesis.

Facile and efficient synthesis of magnetic fluorescent nanocomposites based on carbon nanotubes

Multifunctional nanomaterials composed of magnetic and fluorescent nanoparticles have been one of the most extensive pursuits because of the potential application in bio-research. In this paper, we demonstrated an efficient method by coupling CdSe/CdS/ZnS quantum dots (QDs) with Fe3O4 magnetic nanoparticles(MNPs) while functionalized multiwall carbon nanotubes (f-MWCNTs) were used as matrix to synthesize a kind of magnetic fluorescent nanocomposite. Compared with other matrix materials, carbon nanotubes have the advantages of high surface areas and good biocompatibility. The incorporation of f-MWCNTs supplies plenty of nucleation sites for the preferential growth of Fe3O4 nanoparticles, avoiding the agglomeration phenomenon of Fe3O4 MNPs in traditional co-precipitation method. Moreover, the un-reacted functional groups of f-MCNTs can further adsorb biological species and drugs, averting the decline of fluorescent intensity caused by the modification of biological species and drugs. The synthetic product maintains the unique properties of rapid magnetic response and efficient fluorescence, which shows a broad application prospect in fluorescent labeling, biological imaging, cell tracking and drug delivery.

Novel plasma assisted preparation of ZnCuFeCr layered double hydroxides with improved photocatalytic performance of methyl orange degradation

Plasma assisted preparation of ZnCuFeCr layered double hydroxides used as photocatalyst showed excellent photocatalytic performance on methyl orange degradation under visible light. The catalysts were characterized by XRD, SEM, XPS, BET, UV–Vis DRS, EPR and PL. Compared with the traditional co-precipitation method, the plasma-assisted preparation of layered double hydroxides had obvious advantages of visible light photocatalysis. Plasma assisted preparation resulted in a tighter arrangement of the laminate atoms and more stable crystal structure, increased the specific surface area, generated more oxygen vacancies and reduced photoelectron-hole recombination during photocatalysis. The reaction mechanism of the preparation process and photocatalytic reaction process was inferred. Meanwhile, the effects of preparation time on the degradation were investigated, and the optimal preparation conditions were obtained. The degradation rate of 1000 mL (20 mg/L) methyl orange could reach up to 96.8% within 42 min in visible light photocatalysis under the preparation conditions that discharge voltage of 30.9 kV, photocatalyst addition amount of 1 g/L.

Conversion Synthesis of Self-Standing Potassium Zinc Hexacyanoferrate Arrays as Cathodes for High-Voltage Flexible Aqueous Rechargeable Sodium-Ion Batteries.

Prussian blue analogs exhibit great promise for applications in aqueous rechargeable sodium-ion batteries (ARSIBs) due to their unique open framework and well-defined discharge voltage plateau. However, traditional coprecipitation methods cannot prepare self-standing electrodes to meet the needs of wearable energy storage devices. In this work, a water bath method is reported to grow microcube-like K2 Zn3 (Fe(CN)6 )2 ·9H2 O on carbon cloth (CC) using Zn nanosheet arrays as the zinc source and reducing agent, directly serving as a self-standing cathode. Benefiting from fast ion diffusion and high conductivity, the cathode delivers a high areal capacity of 0.76 mAh cm-2 at 0.5 mA cm-2 and excellent capacity retention of 57.9% as the current density increases to 20 mA cm-2 . By coupling with NaTi2 (PO4 )3 grown on CC as an anode, a quasi-solid-state flexible ARSIB with a high output voltage plateau of 1.6 V is successfully assembled, exhibiting a superior areal capacity of 0.56 mAh cm-2 and energy density of 0.92 mWh cm-2 . In particular, the device shows admirable mechanical flexibility, maintaining 90.3% of initial capacity after 3000 bending cycles. This work is anticipated to open a new avenue for the rational design of self-standing electrodes used in high-voltage flexible ARSIBs.

Highly Crystalline Ni-Co Layered Double Hydroxide Fabricated via Topochemical Transformation with a High Adsorption Capacity for Nitrate Ions.

Layered double hydroxide (LDH) has emerged as promising candidates for removing harmful oxoanions (i.e., SO42-, HPO42-, andNO3- ions) from wastewater because of their intrinsic ability to accommodate anionic species in the interlayer space. Highly crystalline [Ni0.67Co0.33(OH)2]Cl0.29·0.53H2O (Ni-Co LDH) particleswith an exceptionally high anion-exchange capacity of 58.8 mg g-1 and a distribution coefficient (Kd) of 2396 mL g-1 for NO3- ions were successfully prepared by the flux method and a topochemical strategy. Layered Na0.97Ni0.67Co0.33O2 (NNCO) was prepared using a high-temperature flux and used as a starting material for topotactic transformation consisting of oxidative hydrolysis with KOH and NaClO and subsequent reduction with H2O2 and NaCl. During the transformation from NNCO to Ni-Co LDH, a drastic change in the valences of the Ni and Co belonging to the host layer and in the cationic and anionic species occurs in interlayer space; the valences of the Ni and Co in NNCOwereincreased from Ni2+,3+ and Co2+,3+ to Ni3+ and Co2+,3+,4+ by an oxidative hydrolysis reaction with simultaneous intercalation of K+ionsand deintercalation of Na+ions,and subsequentlydecreased from Ni3+ and Co2+,3+,4+ to Ni2+ and Co2+,3+ by a reduction reaction with simultaneous intercalation of anionic species such as CO32- and Cl-ionsand deintercalation of Na+ and K+ions. Through synchrotron powder X-ray diffraction analysis and Rietveld refinement, the resultant Ni-Co LDH was clearly shown to exhibit high crystallinity with less compositional deviation even after topochemical transformation in comparison with the one prepared by traditional coprecipitation and solid-state methods. Furthermore, the adsorption isotherm for NO3- ions elucidated that homogeneous adsorption sites are consistently constructed in the crystal structure, which could be found from the fitting to a Langmuir curve, with the R2 value being 0.98. This work opens up a new route for the fabrication of excellent not only ion-exchangeable but also ion-conductive inorganic materials for direct utilization in environmental and energy-storage processes.

Investigation into chemical function in a Mn4+-activated Li-phase cryolite synthesis for green synthetic design

Herein, a series of obstinate Mn4+-activated Li-phase cryolites Li3GaF6:Mn4+ have been newly synthesized and optimized via solvent composition regulation at traditional co-precipitation reaction. The phase purity, morphology, luminescence property and white light-emitting diode application of as-synthesized phosphor have been carefully investigated. Under 460 nm excitation, Li3GaF6:Mn4+ emits sharp lines at 633 nm with color purity of 99.75%. Notably, more than 15 times emission increment is realized based on partial replacement of toxic HF by CH3COOH (HAc) and little addition of H2O from the pure HF reaction system. The specific functions of chemicals in synthesis process are systematically studied via step-by-step synthesis optimization with single alteration in solvent compositions. It is disclosed that HF was used to dissolve insoluble reagents, provide H+ and F− ions; HAc offered weaker acidity; moderate H2O stimulated the ionization of weak acids. Besides, efficient Li3GaF6:Mn4+ tends to be formed in weaker acid environment with enough F− ions. Importantly, the employment of HAc and H2O immensely reduces the toxicity of reaction system. These findings on chemical function confirmation might enlighten the HF-free green co-precipitation synthesis of Mn4+-doped fluorides by using suitable raw material and solvent combinations.

Synthesis of Active MFe2O4/γ-Fe2O3 Nanocomposites (Metal = Ni or Co) for Reduction of Nitro-Containing Pollutants and Methyl Orange Degradation

Metal-ferrite/maghemite nanocomposites (NiFe2O4/***[Formula: see text]-Fe2O3 and CoFe2O4/[Formula: see text]-Fe2O[Formula: see text] were synthesized via doping maghemite with metal salt (NiCl2 or CoCl[Formula: see text] followed by reduction of metal ions using NaBH4. The synthesized metal-ferrite/maghemite nanocomposites were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), Fourier transform infrared (FTIR) and the amounts of the dopant-metal (Ni/Co) were determined using ICP-OES technique. Results showed that this synthetic route produced nanocomposites with highly active ferrite phases MFe2O4. The synthesized nanocomposites exhibited exceptional catalytic activities for the reduction of 4-nitrophenol and 2-nitroaniline as well as the catalytic degradation of methyl orange. Specific activity parameter of NiFe2O4/[Formula: see text]-Fe2O3 and CoFe2O4/[Formula: see text]-Fe2O3 toward reduction of 4-NP reached 993.9 and 929.8[Formula: see text]s[Formula: see text][Formula: see text]g[Formula: see text], respectively. These high values of specific activities are higher than most reported metal-ferrite composites prepared via traditional co-precipitation methods. Besides, strong magnetic properties of the prepared metal-ferrite/maghemites facilitates easy separation process for several reuses.