Mesoporous ZnFe2O4 Research Articles

A room-temperature operable and stretchable NO2 gas sensor composed of reduced graphene oxide anchored with MOF-derived ZnFe2O4 hollow octahedron

Stretchable and highly sensitive gas sensors are currently receiving great attention due to their pertinence in wearable technology for detecting environmental conditions as well as for human safety. Herein, room-temperature operable, stretchable, highly selective, and stable gas sensors were engineered by decorating networked reduced graphene oxide (rGO) with metal-organic framework-derived zinc ferrite (ZnFe2O4) microparticles on a three-dimensionally micropatterned stretchable polydimethylsiloxane substrate which is mountable on human skin for possible e-skin applications. The effect of mesoporous ZnFe2O4 microparticles concentration on gas sensing performance was investigated. Due to the existence of high-density defect sites in the mesoporous microparticles, the introduction of ZnFe2O4 in the rGO-based chemiresistive sensor demonstrated fast detection performance for nitrogen dioxide (NO2) across a wide range from 50 to 4,000 ppb with improved sensitivity (219.44 % ppm−1) and lower limit of detection (1.49 × 10-4 ppm) compared to the pristine rGO-based sensor. The rGO-ZnFe2O4-based gas sensor showed good reproducibility and stable dynamic responses under application of static and dynamic stretching as well as workability in high humidity (up to 80 %) conditions even in the low concentration range (from 50 to 250 ppb) of NO2. These beneficial features of the stretchable gas sensors demonstrate their excellent potential for wearable gas sensing technology applications.

Construction of mesoporous ZnFe2O4-g-C3N4 nanocomposites for enhanced photocatalytic degradation of acridine orange dye under visible light illumination adopting soft- and hard-template-assisted routines

In this investigation, triblock copolymer surfactant (F-108) as a soft template and mesoporous silica (MCM-41) as a hard template were endorsed to establish mesoporous ZnFe2O4-g-C3N4 nanocomposites of improved features. Photocatalytic remediation of acridine orange dye was endorsed to test the efficiency of the established nanocomposites when exposed to visible light. It has been affirmed by the surface characterization investigation that established nanocomposites acquired improved specific surface areas when correlated with the surface areas of both pure ZnFe2O4 nanoparticles (NPs) and pure g-C3N4 nanosheets. In addition, TEM analysis depicted that ZnFe2O4 nanoparticles (NPs) are homogenously spread on the g-C3N4 surface. Besides, synthesized ZnFe2O4-g-C3N4 nanocomposite accommodating 3 wt.% ZnFe2O4 NPs exhibited reinforced efficacy against photocatalytic decomposition of acridine orange dye when related to that of neat mesoporous ZnFe2O4 NPs as well as that of g-C3N4 nanosheets. Evidently, the photocatalytic remediation achievement of acridine orange acquired by 3 wt.% ZnFe2O4@g-C3N4 nanocomposites was found to be 4.4 times the achievement acquired by neat mesoporous ZnFe2O4 NPs. At the same time, it was 6.3 times the achievement acquired by neat g-C3N4 nanosheets. The fast transference of the reactant molecules through the mesoporous texture, the suppressed rate of the photoinduced charges' recombination, the boosted separation between charges, the diminished band gap energy besides the extended surface area of the synthesized nanocomposites could be considered the most important considerations that contribute strongly to the superior photocatalytic achievement of the synthesized ZnFe2O4-g-C3N4 nanocomposite towards photocatalytic remediation of acridine orange dye. Furthermore, the homogenous distribution of the small-sized ZnFe2O4 NPs onto the nanosheets’ surface participated also the photocatalytic progression of the synthesized nanocomposites. The regenerated ZnFe2O4-g-C3N4 nanocomposite exhibited extensive stability and durability even after recycling up to five runs.

A highly sensitive sensor based on ordered mesoporous ZnFe2O4 for electrochemical detection of dopamine

Accurate and sensitive detection of dopamine (DA) is fundamental to monitor and diagnose certain neurological diseases. Herein, highly ordered mesoporous ZnFe2O4 (OM-ZnFe2O4) is prepared via a facile nanocasting method and shows the highly sensitive in the electrochemical detection of DA. The optimized OM-ZnFe2O4-40 shows the most excellent activity for DA oxidation in a wide linear range from 2 to 600 nM with a quick response time of 5 s, high sensitivity of 0.094 nA nM−1 and a lower detection limit of 0.4 nM (S/N = 3). The electrode modified with OM-ZnFe2O4 is further successfully used to monitor the increase of DA concentration induced by K+-stimulation of living PC12 cells in a neurological environment. This work offers a simple and powerful strategy for designing electrodes for detecting DA in biological systems.

Zinc Ferrite Nanorod‐Assembled Mesoporous Microspheres as Advanced Anode Materials for Sodium‐Ion Batteries

Mesoporous zinc ferrite (ZnFe2O4) microspheres assembled by nanorods are fabricated through a facile hydrothermal approach, followed by a calcination strategy. The fabricated mesoporous ZnFe2O4 has a diameter of approximately 500–800 nm with a high surface area of 91.6 m2 g−1. The utilization of the microspheres that serve as anode materials for sodium‐ion batteries is studied for the first time. The electrochemical results demonstrate that the ZnFe2O4 anode experiences a series of conversion and alloying reactions for reversible sodium storage and exhibits high sodium storage capacity and excellent stability. It exhibits a reversible capacity as high as 350 mAh g−1 after 300 cycles at 100 mA g−1, which is superior to other reported ZnO and ZnMxOy (M = Co, Sn, Ge) electrodes. The existence of the mesoporous structure is responsible for the excellent electrochemical properties of the microspheres, which not only enhances the electrochemical kinetics but also offers additional space to alleviate the strain associated with sodiation/desodiation.

Nanoparticles-assembled ZnFe2O4 mesoporous nanorods for physicochemical and magnetic properties

Hierarchically one dimensional (1-D) mesoporous ZnFe2O4 rods with nanoparticles as their building blocks have been synthesized by the solvothermal approach. The influence of annealing temperature on structural, morphological, optical and magnetic properties was intensively investigated. X-ray diffraction was used to ascertain the phase purity of synthesized samples. To perceive the information on morphological and structural features, field emission scanning electron microscopy and high resolution transmission electron microscopy with energy dispersive spectroscopy was probed. It was observed that nanorods with high aspect ratio were obtained when treated at 600 °C (ZF600) annealing temperature as compared to 400 °C (ZF400). Fourier transform infra-red spectroscopy was resorted to gain the insight of bonding mechanism associated with ZF400 and ZF600. To enrich the study on material chemistry and defects, Raman spectroscopy and X-ray photoelectron spectroscopy was performed. Brunauer–Emmett–Teller envisioned the surface area of ZF400 and ZF600. It was found that surface area decreases with increase in annealing temperature. UV–Vis spectroscopy expounds that the optical band gap increases with annealing temperature from 3.0 to 3.3 eV for ZF400 to ZF600 respectively. Magnetic measurements were performed on vibrating sample magnetometer at room temperature and the results decipher the superparamagnetic nature of the synthesized material. Additionally, saturation magnetization was found to increase with annealing temperature.

Ethanol electrooxidation on high-performance mesoporous ZnFe2O4-supported palladium nanoparticles

As a catalyst for the electrooxidation of ethanol, a well-dispersed mesoporous ZnFe2O4 powder (ZnFe2O4MP) as a support for Pd nanoparticles (PdNPs) was fabricated using solution combustion synthesis, which is an easy and environmentally friendly method.

Upconversion-mediated ZnFe2O4 nanoplatform for NIR-enhanced chemodynamic and photodynamic therapy.

ZnFe2O4, a semiconductor catalyst with high photocatalytic activity, is ultrasensitive to ultraviolet (UV) light and tumor H2O2 for producing reactive oxygen species (ROS). Thereby, ZnFe2O4 can be used for photodynamic therapy (PDT) from direct electron transfer and the newly defined chemodynamic therapy (CDT) from the Fenton reaction. However, UV light has confined applicability because of its high phototoxicity, low penetration, and speedy attenuation in the biotissue. Herein, an upconversion-mediated nanoplatform with a mesoporous ZnFe2O4 shell was developed for near-infrared (NIR) light enhanced CDT and PDT. The nanoplatform (denoted as Y-UCSZ) was comprised of upconversion nanoparticles (UCNPs), silica shell, and mesoporous ZnFe2O4 shell and was synthesized through a facile hydrothermal method. The UCNPs can efficiently transfer penetrable NIR photons to UV light, which can activate ZnFe2O4 for producing singlet oxygen thus promoting the Fenton reaction for ROS generation. Besides, Y-UCSZ possesses enormous internal space, which is highly beneficial for housing DOX (doxorubicin, a chemotherapeutic agent) to realize chemotherapy. Moreover, the T 2-weighted magnetic resonance imaging (MRI) effect from Fe3+ and Gd3+ ions in combination with the inherent upconversion luminescence (UCL) imaging and computed tomography (CT) from the UCNPs makes an all-in-one diagnosis and treatment system. Importantly, in vitro and in vivo assays authenticated excellent biocompatibility of the PEGylated Y-UCSZ (PEG/Y-UCSZ) and high anticancer effectiveness of the DOX loaded PEG/Y-UCSZ (PEG/Y-UCSZ&DOX), indicating its potential application in the cancer treatment field.

A facile and green method of preparation of mesoporous ZnFe2O4 with enhanced adsorption activity

A facile and green method of preparation of mesoporous ZnFe2O4 with enhanced adsorption activity

Mesoporous ZnFe2O4 Photoanodes with Template‐Tailored Mesopores and Temperature‐Dependent Photocurrents

Mesoporous ZnFe2 O4 photoanodes have been prepared via dip-coating utilizing the evaporation-induced self-assembly of two different block-copolymer templates to investigate the influence of pore geometry on the photoelectrochemcial performance of those earth-abundant photoelectrodes. The use of commercial block copolymers, triblock copolymer Pluronic® F127 and the diblock copolymer PIB3000 as templates, leads to different pore morphologies under identical preparation conditions due to different polymer stabilities. Interestingly, pore morphology in mesoporous ZnFe2 O4 turned out to be less important for the photoelectrochemical performance. Contrary, sufficiently developed crystalline domains gained through optimized temperature treatment resulted in maximum photoelectrochemical performance among the investigated samples. This disproves the necessity of expensive, tailor-made polymer soft templates to synthesize high-performing mesoporous ZnFe2 O4 photoanodes.

Insight into the catalytic mechanism of γ-Fe2O3/ZnFe2O4 for hydrogen peroxide activation under visible light

Magnetic γ-Fe2O3 supported on mesoporous ZnFe2O4 was synthesized by impregnation and deposition–precipitation methods. The obtained γ-Fe2O3/ZnFe2O4 was found to be an effective catalyst for the degradation and mineralization of Orange II with H2O2 under visible light irradiation, which can be attributed to the enhanced production of OH and particularly O2−. The catalytic mechanism of γ-Fe2O3/ZnFe2O4 for H2O2 activation and the degradation pathway of Orange II were investigated. The result indicates that the loaded γ-Fe2O3 could capture the electrons in the conductive band of ZnFe2O4, thus promoting the formation of O2− from the reaction between H2O2 and holes. Meanwhile, the formed Fe2+ and electrons could react with H2O2 to produce OH. According to the results of liquid chromatography-mass spectrometry, electron paramagnetic resonance and scavenger experiments, Orange II should be mainly degraded by O2− but not OH due to the destruction of azo bond, while its intermediates were further mineralized by O2− and OH.

Hierarchical hybrid ZnFe2O4 nanoparticles/reduced graphene oxide composite with long-term and high-rate performance for lithium ion batteries

Hierarchical hybrid nanostructure of mesoporous ZnFe2O4 nanoparticles anchored on reduced graphene oxide (ZnFe2O4 NPs/rGO) has been successfully developed in this research via a fast low-temperature refluxing method and a subsequent-annealing treatment in N2. The unique mesoporous network structures of ZnFe2O4 NPs supported by flexible rGO sheets offer sufficient electrode-electrolyte contact, shorten Li+ ions diffusion distance, and thus greatly facilitate the electrochemical reactions via accommodating the volume change efficiently during cycling. Meanwhile, the conductive rGO matrix in the hybrid composite also ensures rapid electron transport to avoid the serve pulverization. Just based on such beneficial synergistic effect, the well-designed hierarchical hybrid ZnFe2O4 NPs/rGO composites present excellent lithium storage performance with high reversible discharge capacity, long-term cycle stability and superb high-rate capability when used as an anode for LIBs. A stable discharge capacity of as high as about 1106.7 mAh g−1 is well maintained even after 400 cycles at the current density of 200 mA g−1. We think this facile strategy could be further extended to the fabrication of other graphene-based electrodes for advanced energy applications.

High efficiency removal of methylene blue using SDS surface-modified ZnFe2O4 nanoparticles

Recent studies have shown that hazardous organic dye substances can be removed from aqueous solutions by spinel ferrite nanomaterials. We found that Sodium Dodecyl Sulfonate (SDS) surface-modified mesoporous ZnFe2O4 nanoparticles (10–50nm) have a remarkably high maximum adsorptive capacity (∼699.30mg/g) for aqueous Methylene Blue (MB) removal at T of 288K and pH of 12. Unmodified ZnFe2O4 nanoparticles suffer from particle agglomeration, which reduces surface area, thus reducing their adsorptive capacity. Here it is shown that when modified with SDS, the specific surface area increased by ∼34%. It is also shown that the anionic SDS surfactant significantly increased the electrostatic attraction to the cationic MB compound. Moreover, it was found that adsorption of MB positively correlated with the aqueous solution’s pH, which is attributed to a stronger negative charge on the SDS modified ZnFe2O4 surface at high pHs. The SDS-modified ZnFe2O4 adsorption of MB fitted well with the Langmuir adsorption isotherm model, and kinetic data fitted into a pseudo-second-order model. Thermodynamic parameters indicated that the adsorption was spontaneous and exothermic in nature, and physisorption dominated the adsorption of MB. The findings of this study demonstrate the potential for enhanced removal of MB contamination from aqueous solutions by SDS-modified ZnFe2O4 nanoparticles and, therefore, the potential for them to remove cationic organic dye from wastewater.

Enhanced photocatalytic activity of mesoporous ZnFe2O4 nanoparticles towards gaseous benzene under visible light irradiation

Mesoporous ZnFe2O4 nanoparticles prepared as a visible light responsive catalyst, the morphology, structure and optical properties of the spinel oxide are characterised, diligently. Photocatalytic activity of ZnFe2O4 nanoparticles assessed towards the oxidation of gaseous benzene. A comparative study conducted, between ZnFe2O4 and Fe2O3, in terms of water and benzene adsorption using microcalorimetry as well as photocatalytic benzene oxidation. In this context, ZnFe2O4 showed greater activity than Fe2O3. The heats of water adsorption for the spinel and hematite are −270kJ/mol and −190kJ/mol, respectively; revealing the dissociative mode of the adsorption, which is crucial for the generation of hydroxyl radicals. Moreover, the heat of benzene adsorption for ZnFe2O4 and Fe2O3 are −167kJ/mol and −139kJ/mol, respectively. Finally, the intermediate (phenol) and products (H2 & CO2) of the oxidation reaction is monitored by GC (FID/TCD) and DRIFT: a mechanism is proposed accordingly for the photocatalytic oxidation of the benzene.

Synthesis of ZnFe2O4 nanoparticles for photocatalytic removal of toluene from gas phase in the annular reactor

Abstract Spinel type mesoporous ZnFe2O4 nanoparticles were synthesized by sol-gel auto combustion method and characterized by XRD, FE-SEM, DRS and BET. XRD pattern of prepared nanocrystals showed that ZnFe2O4 spinel formed in cubic structure and the mean crystallite size was 25 nm. FE-SEM image showed that prepared particles were in nanoscale with low aggregation and porous structure. From DRS results, the optical band gap was calculated about 1.87 eV. From BET analysis, specific surface area of prepared nanoparticles was obtained 39 m2/g. The prepared nanoparticles application was studied on the removal of toluene from gas phase by photocatalytic process under UV and visible irradiation in the annular photoreactor. The prepared nanoparticles were capable to remove about 60% of toluene with 900 ppmv concentration. The prepared nanoparticles had more efficiency than commercial ZnO and TiO2 nanoparticles in the photocatalytic removal of toluene. The operational parameters such as initial concentration of pollutant, catalyst loading, photoreactor humidity and light intensity were studied.

Mesoporous ZnFe2O4 prepared through hard template and its acetone sensing properties

Mesoporous ZnFe2O4 with ordered tunnel and large specific surface area has been successfully prepared through hard template (mesoporous silica KIT-6). The necessary characterizations such as X-ray diffraction (XRD), Brunauer-Emmet-Teller (BET), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) have been carried out to investigate the obtained material. ZnFe2O4 with mesoporous structure presents excellent crystallinity and periodic mesostructure. The sensing properties of gas sensor based on ZnFe2O4 mesoporous material towards acetone has been investigated. The sensor presents outstanding sensitivity, selectivity and longtime stability. This indicates that the obtained mesostructured ZnFe2O4 through hard template method is a potential acetone gas sensor material.

Hierarchical growth of ZnFe2O4 for sensing applications

Selective sensing of toxic heavy metals Hg(ii) and environmentally hazardous acetone vapour using mesoporous ZnFe2O4 NFs, synthesized from our laboratory developed modified hydrothermal technique.

Stable mesoporous ZnFe2O4 as an efficient electrocatalyst for hydrogen evolution reaction

Stable mesoporous spinel ZnFe2O4 with large surface area, and small particle size was successfully prepared via a surface binding strategy as an efficient catalyst for electrochemical hydrogen generation in acidic water. Experimental results show that the mesoporous structure could be maintained up to 700°C after stabilizing treatment of the sample. The prepared mesoporous ZnFe2O4 exhibited better electrocatalytic activity and excellent electrochemical durability than the corresponding sample prepared without surface binding treatment.

A novel approach to facilely synthesize mesoporous ZnFe2O4 nanorods for lithium ion batteries

Despite the fact that ZnFe2O4 has various advantages as promising anode materials for lithium ion batteries (LIBs), ZnFe2O4 chronically suffers from limited cycle life, originating from poor electronic conductivity and huge volume changes. In this study, we address these traditional issues of ZnFe2O4 by fabricating a mesoporous nanorod structure through a novel, facile and scalable co-precipitation approach followed by thermal decomposition. The unique nanostructure not only effectively shortens the pathway for Li+ diffusion, but also provides a high porosity to effectively tolerate volume variation during charge/discharge processes. The reversible capacity of ZnFe2O4 can still reach 983 mAh g−1 at a specific current of 100 mA g−1 after 50 cycles. Mesoporous ZnFe2O4 nanorod could be demonstrated as a promising anode material for lithium-ion batteries.

Green Template-Free Synthesis of Hierarchical Shuttle-Shaped Mesoporous ZnFe2 O4 Microrods with Enhanced Lithium Storage for Advanced Li-Ion Batteries.

Invited for the cover of this issue is Changzhou Yuan and co-workers at the Anhui University of Technology. The image depicts hierarchical shuttle-shaped mesoporous ZnFe2 O4 micro-rods, as a low-cost yet high-performance anode, for advanced next-generation Li-ion batteries. Read the full text of the article at 10.1002/chem.201501876.

Green Template-Free Synthesis of Hierarchical Shuttle-Shaped Mesoporous ZnFe2 O4 Microrods with Enhanced Lithium Storage for Advanced Li-Ion Batteries.

In the work, a facile and green two-step synthetic strategy was purposefully developed to efficiently fabricate hierarchical shuttle-shaped mesoporous ZnFe2 O4 microrods (MRs) with a high tap density of ∼0.85 g cm(3) , which were assembled by 1D nanofiber (NF) subunits, and further utilized as a long-life anode for advanced Li-ion batteries. The significant role of the mixed solvent of glycerin and water in the formation of such hierarchical mesoporous MRs was systematically investigated. After 488 cycles at a large current rate of 1000 mA g(-1) , the resulting ZnFe2 O4 MRs with high loading of ∼1.4 mg per electrode still preserved a reversible capacity as large as ∼542 mAh g(-1) . Furthermore, an initial charge capacity of ∼1150 mAh g(-1) is delivered by the ZnFe2 O4 anode at 100 mA g(-1) , resulting in a high Coulombic efficiency of ∼76 % for the first cycle. The superior Li-storage properties of the as-obtained ZnFe2 O4 were rationally associated with its mesoprous micro-/nanostructures and 1D nanoscaled building blocks, which accelerated the electron transportation, facilitated Li(+) transfer rate, buffered the large volume variations during repeated discharge/charge processes, and provided rich electrode-electrolyte sur-/interfaces for efficient lithium storage, particularly at high rates.