Magnetically Separable Fe3O4 Nanoparticles-Decorated Reduced Graphene Oxide Nanocomposite for Catalytic Wet Hydrogen Peroxide Oxidation

Fe₃O₄ nanoparticles-decorated reduced graphene oxide magnetic nanocomposites (Fe₃O₄/rGO NCs) were prepared by a facile one-step strategy, and further used as heterogeneous Fenton-like catalysts for catalytic wet hydrogen peroxide oxidation (CWHPO) of methylene blue (MB) at 25 °C and atmospheric pressure. The effects of variables such as the Fe₃O₄/rGO with the mass ratio of rGO, initial pH, MB concentration and H₂O₂ dosage were investigated. The Fe₃O₄/rGO NCs with rGO mass ratio of 10.0 wt % showed the highest H₂O₂-activating ability, which was six-fold than that of pure Fe₃O₄ nanoparticles (NPs). The resulting catalysts demonstrated high catalytic activity in a broad operation pH range from 5 to 9, and still retained 90.5 % catalytic activity after reuse in five cycles. Taking advantage of the combined benefits of rGO and magnetic Fe₃O₄ NPs, these Fe₃O₄/rGO NCs were confirmed as an efficient heterogeneous Fenton-like catalyst for CWHPO to treat organic pollutants. And a reasonable catalytic mechanism of Fe₃O₄/rGO NCs was proposed to interpret the degradation process.     

The effect of GO loading on electromagnetic wave absorption properties of Fe3O4/reduced graphene oxide hybrids

Ideal electromagnetic absorbing materials with lightweight and high efficiency have broad application outlook in military and civil fields. In this work, a 3D nanostructure material by hybridizing Fe₃O₄ nanocrystals and reduced graphene oxide (Fe₃O₄/rGO) were synthesized through an environmental-friendly one-pot solvothermal method. The effect of GO loading on electromagnetic (EM) wave absorption characteristic of Fe₃O₄/rGO was investigated. The introduction of rGO sheets not only prevented Fe₃O₄ from agglomerating, also improved the absorption performance of Fe₃O₄/rGO hybrids. With an appropriate addition, Fe₃O₄/rGO obtained a minimum reflection loss (RL) of −22.7 dB and the absorption bandwidth was 3.13 GHz (90% absorption).     

Nanocrystalline transition metal oxides and their composites with reduced graphene oxide and carbon nanotubes for photocatalytic applications

Transition metal oxide nanoparticles (CuO, ZnO & Fe₂O₃) and mixed metal oxides CuO. ZnO.Fe₂O₃ were fabricated by facile co-precipitation approach for photocatalytic treatment of organic dyes. The structural features, phase purity, crystallite size and morphology of individual and mixed metal oxides were analysed by X-rays diffraction patterns (XRD) and scanning electron microscopic (SEM) analysis. Electrical behaviour of CuO, ZnO, Fe₂O₃ and mixed metal oxides CuO. ZnO.Fe₂O₃ was explored by current-voltage (I-V) measurements. Functional groups present in the synthesized metal oxides were investigated by Fourier transform infrared spectroscopy (FTIR) which ensures the existence of M-O functional groups in the samples. The optical bandgap analysis was carried out by UV–visible spectroscopic technique which revealed that the blend of three different transition metal oxides reduced the bandgap energy of mixed metal oxides. The reason behind this reduced bandgap energy is formation of new electronic state which arises due to the metal-oxygen interactions. Moreover, the nanocomposites of CuO.ZnO.Fe₂O₃ with reduced graphene oxide (rGO) and carbon nanotubes (CNTs) were prepared to study the effect of the carbonaceous materials on the rate of photodegradation. These carbonaceous nanomaterials have plethora properties which can bring advancement in sector of photocatalytic treatment of wastewater. The photocatalytic experiments were performed using methylene blue (MB) as standard dye for comparative study of metal oxides and their composites with rGO and CNTs. The percentage degradation of methylene blue (MB) by nanocomposite CuO.ZnO.Fe₂O₃/rGO is 87% which is prominent among all samples. This result ascribed the photocatalytic aspects of reduced graphene oxide along with mixed metal oxides.     

Room temperature in situ chemical synthesis of Fe3O4/graphene

A simple, cost-effective, efficient, and green approach to synthesize iron oxide/graphene (Fe₃O₄/rGO) nanocomposite using in situ deposition of Fe₃O₄ nanoparticles on reduced graphene oxide (rGO) sheets is reported. In the redox reaction, the oxidation state of iron(II) is increased to iron(III) while the graphene oxide (GO) is reduced to rGO. The GO peak is not observed in the X-ray diffraction (XRD) pattern of the nanocomposite, thus providing evidence for the reduction of the GO. The XRD spectra do have peaks that can be attributed to cubic Fe₃O_4. The field emission scanning electron microscopy (FESEM) images show Fe₃O₄ nanoparticles uniformly decorating rGO sheets. At a low concentration of Fe²⁺, there is a significant increase in the intensity of the FESEM images of the resulting rGO sheets. Elemental mapping using energy dispersive X-ray (EDX) analysis shows that these areas have a significant Fe concentration, but no morphological structure could be identified in the image. When the concentration of Fe²⁺ is increased, the Fe₃O₄ nanoparticles are formed on the rGO sheets. Separation of the Fe₃O₄/rGO nanocomposite from the solution could be achieved by applying an external magnetic field, thus demonstrating the magnetic properties of the nanocomposite. The Fe₃O₄ particle size, magnetic properties, and dispersibility of the nanocomposite could be altered by adjusting the weight ratio of GO to Fe²⁺ in the starting material.     

ZnO/Cr2O3 catalyst for reverse-water-gas-shift reaction of CAMERE process

The stability and the activity of Fe₂O₃/Cr₂O₃ and ZnO/Cr₂O₃ catalysts were examined for a reverse-watergas-shift reaction (RWReaction). The initial activities of those catalysts were quite high so that the conversion reached close to equilibrium. The activity of Fe₂O₃/Cr₂O₃ catalyst decreased from 33.5 to 29.8% during the RWReaction for 75 h at 873 K with GHSV (ml/gcat · h) of 100,000. Moreover, the coke formation on the Fe₂O₃/Cr₂O₃ catalyst caused clogging in the RWReactor of the CAMERE process. On the other hand, the ZnO/Cr₂O₃ catalyst showed no coke formation and no deactivation for the RWReaction at 873 K with GHSV (ml/gcat · h) of 150,000. The ZnO/Cr₂O₃ was a good catalyst for the RWReaction of the CAMERE process.     

Influence of Fe3O4 nanoparticles decoration on dye adsorption and magnetic separation properties of Fe3O4/rGO nanocomposites

Magnetite (Fe₃O₄) nanoparticles were prepared by solvothermal method and its composites with reduced graphene oxide namely FG1, FG2, and FG3 (changing magnetite precursor loading 0.1, 0.5, and 1 respectively) were used as adsorbents for the removal of methyl violet (MV) dye. The structural and morphological results confirm that rGO sheets were decorated with Fe₃O₄ and it ensures the variation of active sites toward dye removal property. The maximum adsorption capacity obtained for FG2 was 196 mg/g. The adsorption isotherms and kinetics better fit Langmuir and pseudo-second-order kinetic model for FG1 and FG2. Increasing of Fe₃O₄ loading on rGO reduces the dye adsorption sites and too low Fe₃O₄ loading affects the magnetic separation. The optimal loading of Fe₃O₄ on rGO is important parameter for the adsorption process and fast separation of adsorbent.     

Fe3O4-intercalated reduced graphene oxide nanocomposites with enhanced microwave absorption properties

Fe₃O₄-intercalated reduced graphene oxide (Fe₃O₄-rGO) nanocomposites were synthesized by an in situ reduction process. The results of XRD and XPS analyses suggested the successful formation of a Fe₃O₄ crystal phase within the rGO sheets. The SEM and TEM images demonstrated that Fe₃O₄ was flaky and was inserted stably within the rGO layers to form a typical sandwich-like structure. The hysteresis loops revealed the superparamagnetic behavior of the Fe₃O₄-rGO nanocomposites at room temperature. The electromagnetic parameters revealed that Fe₃O₄-rGO nanocomposites exhibited multiple dielectric relaxation and magnetic resonance. The reflection loss revealed that the maximum loss was −49.53 dB at 6.32 GHz for a thickness of 3.4 mm while the highest effective absorption bandwidth was 2.96 GHz.     

Preparation of pod-like 3D Ni0.33Co0.67Fe2O4@rGO composites and their microwave absorbing properties

The ferrite/reduced graphene oxide (rGO) composites have attracted increasing attention due to the combination of the dielectric loss of rGO and the magnetic loss of ferrites. In this paper, pod-like 3D Ni_0.33Co_0.67Fe₂O₄@rGO composites were prepared using a solvothermal reaction followed by cold quenching. The structures and morphologies of as obtained composites were characterized using X-ray diffractometer, Raman microscope, photoelectron spectroscopy, scanning electron microscope and transmission electron microscope. The Ni_0.33Co_0.67Fe₂O₄ microspheres with a diameter of 100–150?nm were wrapped in rGO rolls due to the shrinkage of rGO in liquid nitrogen. The rGO sheets with ferrite microspheres wrapped in form the pod-like 3D network morphology. The minimum reflection loss of as-prepared composites reaches ?47.5?dB and the absorption bandwidth (RL<?10?dB) is 5.02?GHz. The composites show much better absorbing performances than pure Ni_0.33Co_0.67Fe₂O₄ microspheres and Ni_0.33Co_0.67Fe₂O₄-rGO mixture formed by mechanically blending of cold quenched pure rGO and ferrite microspheres.     

Hybrid organic-inorganic Cu(II) iminoisonicotine@TiO2@Fe3O4 heterostructure as efficient catalyst for cross-couplings

Two novel mononuclear copper (II) complex catalysts were synthesized from a new tridentate iminoisonicotine ligand (HL) by coordination with Cu(II) ion, with (CuL@TiO₂@Fe₃O₄) and without (CuL) immobilization on TiO₂-coated nanoparticles of Fe₃O₄. The ester moiety on the back of the ligand was utilized for immobilization on nanoparticles of Fe₃O₄. Both ligand and CuL complex were fully characterized by using alternative spectral techniques (nuclear magnetic resonance, infrared, ultraviolet-visible and mass spectroscopy, and elemental analyses). Different analytical techniques were used to identify the structural feature and morphology of the immobilized copper catalyst (CuL@TiO₂@Fe₃O₄) shell-shell-core system. The structural analysis revealed that the catalyst system is composed of both agglomerated nanospheres and deformed nanorods. Both copper catalysts, immobilized CuL@TiO₂@Fe₃O₄ and un-immobilized CuL were studied in heterogeneous and homogeneous catalysis, respectively, for Suzuki-Miyaura (C–C) and Buchwald-Hartwig (C–N) cross-coupling reactions of various heteroaryl halides. Both catalysts showed good catalytic potential under the controlled optimal reaction conditions. In contrast to the homogeneous catalyst (CuL), the heterogeneous catalyst (CuL@TiO₂@Fe₃O₄) showed slightly better catalytic performance. The characteristic obtains supported the catalytic potential of the current samples. Reusability/recycling of both catalysts was also investigated in C–C cross-coupling reactions. It was found that the homogeneous catalyst (CuL) could be only recycled up to three times, whereas the heterogeneous one (CuL@TiO₂@Fe₃O₄) could be reused up to seven times with good efficiency.     

Fe3O4/ZnO/CoWO4 nanocomposites: Novel magnetically separable visible-light-driven photocatalysts with enhanced activity in degradation of different dye pollutants

A series of novel magnetically separable Fe₃O₄/ZnO/CoWO₄ nanocomposites with different contents of CoWO₄ were fabricated using a facile refluxing method at 96 °C followed by a calcination step. The structure, purity, morphology, spectroscopic, and magnetic properties of the prepared samples were characterized by XRD, EDX, SEM, TEM, UV–vis DRS, FT-IR, PL, and VSM techniques. Photocatalytic activity of the nanocomposites was investigated by degradation of rhodamine B, methylene blue, methyl orange, and fuchsine under visible-light irradiation. The results showed remarkably enhanced activity for the Fe₃O₄/ZnO/CoWO₄ (30%) nanocomposite relative to the Fe₃O₄/ZnO and Fe₃O₄/CoWO₄ samples. The degradation rate constant of RhB over the optimal nanocomposite is nearly 24 and 5 times higher than those of the Fe₃O₄/ZnO and Fe₃O₄/CoWO₄ samples, respectively. The intensive absorption of visible light and separation efficiency of the photogenerated electron–hole pairs in the ternary nanocomposites were confirmed by UV–vis DRS and PL techniques, respectively. In addition, a plausible mechanism for separation of the electron–hole pairs based on p–n heterojunction was proposed.     

Heterogeneous Fenton degradation of Orange II by immobilization of Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles onto Al-Fe pillared bentonite

A novel catalyst, Fe₃O₄ nanoparticle decorated Al-Fe pillared bentonite (Fe₃O₄/Al-Fe-P-B), was prepared by in situ precipitation oxidization method. The catalyst was characterized by SEM, XRD and Raman spectroscopy. The Fe₃O₄ nanoparticles mainly exist on the surface or enter into the pore of bentonite, with better dispersing and less coaggregation. The catalytic activity of Fe₃O₄/Al-Fe-P-B was investigated in the degradation of Orange II (OII) by heterogeneous Fenton-like process. The effects of initial concentration of hydrogen peroxide, catalyst loading, temperature and initial pH on the degradation of OII were investigated. The Fe₃O₄/Al-Fe-P-B showed higher degradation efficiency of OII than bare Fe₃O₄ or Al-Fe-P-B in the degradation experiment. The enhanced catalytic activity of Fe₃O₄/Al-Fe-P-B in heterogeneous Fenton system was due to the synergistic effect between Al-Fe-P-B and Fe₃O₄. The novel catalyst can achieve solid-liquid separation easily by sample magnetic separation and has a good reusability and stability.     

Efficiency and Mechanism of Ciprofloxacin Hydrochloride Degradation in Wastewater by Fe3o4/Na2S2O8

ABSTRACT

The nanosized Fe₃O₄ catalyst was synthesized via a modified reverse coprecipitation method and characterized by means of a scanning electron microscope (SEM) and an X-ray diffraction (XRD) analysis instrument. The degradation efficiency and reaction rate of Fe₃O₄ in activating sodium persulfate used to degrade ciprofloxacin were determined from the catalyst dosage, oxidant concentration, and initial pH. The results showed that under the optimum conditions of a catalyst dosage of 2.0 g·L^?1, a sodium persulfate concentration of 1.0 g·L^?1, and an initial pH of 7, the degradation rate of ciprofloxacin was 93.73%, the removal rate of total organic carbon was 78%, and the first-order reaction constant was 0.06907 min^?1 within 40 min. It was also demonstrated that the reactive oxygen species in the Fe₃O₄/sodium persulfate catalytic system were mainly composed of SO₄^– and supplemented by OH· and HO₂· using probe compounds such as ethanol, tertiary butanol, and benzoquinone.     

Synthesis of ultrathin carbon dots-coated iron oxide nanocubes decorated with silver nanoparticles and their excellent catalytic properties

A facile ultrasonic method has been successfully developed for the fabrication of multifunctional Fe₃O₄@carbon dot/Ag (Fe₃O₄@C-dot/Ag) nanocubes (NCs), and the resulting materials are well characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), Vibrating sample magnetometer (VSM) and fluorescence measurements. The Ag nanoparticles (NPs) are uniform and well dispersed on the surface of Fe₃O₄@C-dot, while maintaining the shape and the size of the core-shell Fe₃O₄@C-dot NCs. In addition, its catalytic activities are evaluated by measuring the reduction of p-nitroaniline (p-NA) and crystal violet (CV), and the composite materials exhibit excellent catalytic activity towards reduction of p-NA and CV dye, which is superior to most reported catalysts. The good catalytic performance of Fe₃O₄@C-dot/Ag NCs may be attributed to the specific characteristics of its nanostructure and the synergistic effect on the delivery of electrons between Ag NPs and Fe₃O₄@C-dot NCs. Furthermore, the as-prepared catalysts also show good activity for the reduction of other nitrobenzene analogs. The effect of solvent and reducing agent was also studied on the catalytic activity of Fe₃O₄@C-dot/Ag NCs. Most importantly, the Fe₃O₄@C-dot/Ag catalyst shows excellent recycling stabilities, which can be potentially applied in the fields of catalysis and green chemistry.     

Glass formation and properties of sodium zinc phosphate glasses doped with ferric oxide

ABSTRACT

Approximate glass-forming region of a P₂O₅–ZnO–Na₂O (PZN) ternary system was investigated and determined. The properties of the glasses with ZnO contents between 35 and 50?mol-% were further investigated. When ZnO of 40P₂O₅–40ZnO–20Na₂O glasses is replaced by 1–5?mol-% Fe₂O₃, respectively, the density, T_g and T_f increase first and then decrease, and they showed the maximum value of about 4?mol-% Fe₂O₃ replacement, while CTE and weight loss vary in opposite ways and showed the minimum value at about 4?mol-% Fe₂O₃ replacement. Structural studies were carried out by X-ray diffraction, infrared spectroscopy and Raman spectroscopy. With the increase in Fe₂O₃, the reduction of P=O bond is the main reason for the increase in water resistance of PZNF glass.     

Targeted Heating of Enzyme Systems Based on Photothermal Materials

This study demonstrates that the enzymatic reaction rate can be increased significantly by targeted heating of the microenvironment around the enzyme, while maintaining the reaction system at environmental temperature. Enzyme molecules are covalently attached to the surface of Fe₃O₄@reduced graphite oxide (rGO). Under visible-light irradiation, the reaction rate catalyzed by the enzyme–Fe₃O₄@rGO system is clearly enhanced relative to that of the free enzyme and a mixture of free enzyme and Fe₃O₄@rGO. This local heating mechanism contributes to promotion of the enzymatic reactions of the targeted heating of the enzyme (THE) system, which has been validated by using different enzymes, including lipase, glucose oxidase, and organophosphorus hydrolase. These results indicate that targeted heating of the catalytic centers has the same effect on speeding up reactions as that of traditional heating methods, which treat the whole reaction system. As an example, it is shown that the THE system promotes the sensitivity of an enzyme screen-printed electrode by 14 times at room temperature, which implies that the THE system can be advantageous in improving enzyme efficiency, especially if heating the entire system is impossible or could lead to degradation of substrates or damage of components, such as in vitro bioanalysis of frangible molecules or in vivo diagnosis.     

Iron oxide supercapacitor of high volumetric energy and power density using binder-free supersonic spraying and self-healing rGO

Iron oxide (Fe₂O₃) nanoparticles and reduced graphene oxide (rGO) sheets were supersonically sprayed onto a nickel substrate to fabricate flexible supercapacitors. The supersonic impact velocity was adjusted by varying the air chamber pressure from 2 to 6 bar, which facilitated the self-healing of Stone-Wall defects in rGO sheets. Supersonic spraying caused exfoliation of the rGO sheets, which in turn increased the surface area and adherence of the Fe₂O₃ nanoparticles. The optimal case exhibited a specific capacitance of 1.44 F?cm^-2 at a current rate of 1.5 mA?cm^-2 and the energy density was 14.23 mWh?cm^-3 at 250 mW?cm^-3. The width of the potential window increased to 1.4 V, implying a significant increase in the energy storage capability. The energy density of the supersonically sprayed Fe₂O₃/rGO electrode also showed no signs of deterioration even when the increased current density interfered with the electrode performance.     

Degradation Effect and Mechanism of Dinitrotoluene Wastewater by Magnetic Nano-Fe3O4/H2O2 Fenton-like

The characteristics and influencing factors for dinitrotoluene degradation by nano-Fe₃O₄-H₂O₂ were studied, and the nano-scale Fe₃O₄ catalyst was prepared by the coprecipitation method, with dinitrotoluene wastewater as the degradation object. The results showed that the catalytic reaction system within the pH value range of 1 to 9 could effectively degrade dinitrotoluene, and the optimal pH value was 3; with the increase of catalyst dosage, the degradation efficiency and the catalytic reaction rate of dinitrotoluene grew as well. The optimal catalyst dosage was 1.0 g/L when the H₂O₂ dosage was within the range of 0 to 0.8 mL/L; the degradation efficiency and reaction rate grew with the increase of H₂O₂ dosage. With further increase of H₂O₂ dosage, degradation efficiency and reaction rate decreased; under the best conditions with the H₂O₂ dosage of 0.8 mL/L, the catalyst concentration of 1 g/L and the pH value of 3 at room temperature (25 °C), the degradation rate of the 100-mg/L dinitrotoluene in 120 min reached 97.6%. Through the use of the probe compounds n-butyl alcohol and benzoquinone, it was proved that the oxidation activity species in the nano-Fe₃O₄-H₂O₂ catalytic system were mainly hydroxyl radical (?OH) and superoxide radicals (HO2 ?), based on which, the reaction mechanism was hypothesized.     

Fe3O4@poly(2-hydroxyethyl methacrylate)-graft-poly(?-caprolactone) magnetic nanoparticles with branched brush polymeric shell

Well-defined monodisperse Fe₃O₄@poly (2-hydroxyethyl methacrylate)-graft- poly(ε-caprolactone) (Fe₃O₄@PHEMA-g-PCL) magnetic nanoparticles with novel topological structure, i.e., with branched brush polymeric shell, were successfully prepared by the combination of atom transfer radical polymerization (ATRP) and ring-opening polymerization (ROP). Oleic acid stabilized monodisperse Fe₃O₄ nanoparticles were prepared by a convenient organic phase process and underwent a ligand exchange process with 2-bromo-2-methylpropionic acid (Br-MPA) to generate macroinitiator (Fe₃O₄@Br-MPA) for ATRP of 2-hydroxyethyl methacrylate (HEMA) to produce Fe₃O₄@poly(2-hydroxyethyl methacrylate) (Fe₃O₄@PHEMA). PCL segments were grafted from the side of PHEMA by the ROP of ε-caprolactone (CL) with the hydroxyl groups of PHEMA segments used as initiation centers, and then Fe₃O₄@PHEMA-g-PCL magnetic nanoparticles were obtained. PCL segments of Fe₃O₄@PHEMA-g-PCL possessed lower degree of crystallinity than that of linear PCL. Meanwhile, Fe₃O₄@PHEMA-g-PCL nanoparticles showed superparamagnetism and comparatively strong magnetization. In vitro degradation investigation indicated that the degradation rate of PCL segments in Fe₃O₄@PHEMA-g-PCL increased with the decrease of the length of PCL chains. The release behavior of model drug chlorambucil from the nanoparticles indicated that the rate of drug release could be adjusted by altering the chain-length of PCL segments.     

Rhombic Fe2O3 lumps doping hollow ZnFe2O4 spheres through oxidative decomposition process implanted into graphene conductive network with superior electromagnetic wave absorption properties

Conductor-dielectric-magnetic multicomponent coordination composites with rhombic Fe₂O₃ lumps doping hollow ZnFe₂O₄ spheres through oxidative decomposition process implanted into graphene conductive network (hollow ZnFe₂O₄ spheres/rhombic Fe₂O₃ lumps/rGO composites) were successfully constructed by a facile method. The countless hollow ZnFe₂O₄ spheres were compactly attached to the curled-paper rGO and larger sized-rhombic Fe₂O₃ lumps were relatively dispersed. Among, the hollow structure of ZnFe₂O₄ spheres could attenuate the electromagnetic wave by multiple reflections and scatterings. Intriguingly, hollow ZnFe₂O₄ spheres reacted with GO to form intermediate rhombic Fe₂O₃ lump products, which ameliorated the hetero-interfaces structure and helped to improve impedance matching by weakening the strong magnetic ZnFe₂O₄ (M_s = 91.2 emu/g) and high conductive rGO after the introduction of weakly magnetic Fe₂O₃ semiconductor. Moreover, all three components could induce dielectric polarization losses, such as multilayer or dipole polarization. Therefore, the maximum absorption of ternary composites was up to ?64.3 dB at 7 GHz and 3.4 mm, simultaneously, and a bandwidth exceeding ?10 dB was 4.2 GHz at 1.7 mm. Meanwhile, with a thin thickness range of 1.5–5 mm, the absorption bandwidth below ?10 dB was from 2 to 18 GHz which occupied for 91.5% of whole study frequency range. These results provided a new approach and reference for the design and property regulation of electromagnetic materials at electronic communications, aerospace and military radar flied.     

Surface tuning of the photoelectrochemical properties of oblique angle co-sputtered ZnxFeyO films by Fe concentration

Complex three-dimensional nanosheet structure of Zn_xFe_yO was prepared by highly stable co-sputtering oblique angle deposition. Scanning electron microscopy was employed to observe surface morphology evolution of Zn_xFe_yO with different Fe concentrations. X-ray diffraction was employed to analyze compositions of ZnO, ZnFe₂O₄, and ZnFe₂O₄/Fe₂O₃ with Fe doping. Furthermore, specific nanostructures of Zn_xFe_yO decreased band gap and increased visible-light absorption ability. The ZnFe₂O₄/Fe₂O₃ sample exhibited higher photocatalytic efficiency than those of other films for the degradation of methylene blue. Addition of Fe led to the enhancement of photoelectrochemical properties of ZnFe₂O₄/Fe₂O₃ compared to pure ZnO and Fe₂O₃, and photocurrent response of ZnFe₂O₄/Fe₂O₃ was ~10 times than that of pure ZnO at constant potential of −0.2 V (vs. Ag/AgCl).