Simple Co-precipitation Method Research Articles

Graphitic Carbon Nitride Incorporated Europium Molybdate Composite as an Enhanced Sensing Platform for Electrochemical Detection of Carbendazim in Agricultural Products

The widespread use of carbendazim insecticides has caused substantial concerns to human health due to their coexistence, high toxicity, and persistence. Therefore, it is crucial to develop a carbendazim detection more important for the protection of both humans and the environment safety. A graphitic carbon nitride/europium molybdate (g-C3N4/EuMoO4) composite was fabricated using a simple coprecipitation method and utilized for the selective detection of carbendazim. The glassy carbon electrode (GCE) was fabricated with g-C3N4/EuMoO4 composite electrode (GCE/g-C3N4/EuMoO4) was simple, affordable, and offers an excellent platform for the detection of carbendazim. The structure formation was validated by suitable microscopic and spectroscopic techniques. Under optimal conditions, the GCE/g-C3N4/EuMoO4 electrode showed excellent electrochemical properties for the detection of carbendazim with a low detection limit (0.04 μM) (S/N = 3), a large linear response range of 50–400 μM, and high sensitivity (1.41 μAμM−1cm−2). The findings demonstrated that the developed method can be used to analyze food samples. The g-C3N4/EuMoO4 demonstrates greater sensitivity toward the electrochemical detection of carbendazim compared with the previous sensors. The GCE/g-C3N4/EuMoO4 electrode was utilized to detect carbendazim in real samples, and the results were satisfactory. Furthermore, the GCE/g-C3N4/EuMoO4 modified electrode offers several interesting properties, stability, reproducibility, repeatability, low cost, and practical applications.

Investigation on the synthesis of Mn3O4 nanoparticles embedded on nano rods as an electrode material for supercapacitor application

. • Facile synthesis of Mn 3 O 4 (Hausmannite) was performed via simple Co-precipitation method. • Fabricated Electrode reveals excellent specific capacitance of 499 F/g at 1mV/s in 1M Na 2 SO 4. • 75% of specific capacitance is retained even after 5000 cycles. Many studies are being conducted in the field of energy storage devices to improve the performance of electrode materials for future application. In recent years, numerous research have been published that fully define Nano level synthesis techniques, dopant and composite-based work for improving the charge storing capability and long cycle life of energy storage devices, particularly in supercapacitors. In this current era, researchers prefer eco-friendly synthesis techniques to rectify unnecessary hazardous issues. Since, environmental friendly technic along with good cyclic stability was one of the major focuses in scientific society. Here, the present paper concentrates on the synthesis of Trimanganese Tetroxide / Mn 3 O 4 (Hausmannite) under a facile co-precipitation technique. Upon Co-precipitation based technique the formations of nanoparticles cramped on nanorods occur simultaneously. The three electrode supercapacitor cell system composed of Mn3O4 shows high capacitance and capacity retention. The highest specific capacitance of 499 F/g is achieved at a scanning rate of 1 mV/s, with 75% of retention after 5000 cycles in 1M Na 2 SO 4 aqueous electrolyte.

Nanoflower-like BiOBr/TiO2 p-n heterojunction composites for enhanced photodegradation of formaldehyde and dyes

A nanoflower-like BiOBr/TiO 2 p-n heterojunction photocatalyst was constructed and the possible photocatalytic mechanism was proposed. The construction of BiOBr/TiO 2 p-n heterojunction can significantly enhance the degradation of methyl orange (MO) and gaseous formaldehyde (HCHO) by photocatalysts. • A efficient nanoflower-like p-n heterojunction photocatalyst BiOBr/TiO 2 was prepared by simple solution coprecipitation. • This catalyst has enhanced photocatalytic degradation of dyes and formaldehyde. • P-n heterojunction effectively separates photogenerated carriers of BiOBr, hindering recombination of electrons and holes. The fabrication of p-n heterojunction is a smart strategy to improve the photocatalytic activity, because p-n junction can effectively promote the separation of photogenerated charges and improve the photocatalytic performance. Herein, a low cost nanoflower-like p-n heterojunction photocatalyst BiOBr/TiO 2 (abbreviated as BT-x) was prepared by simple solution coprecipitation method. Under visible light, BiOBr/TiO 2 p-n heterojunction photocatalyst showed enhanced photocatalytic activity in the degradation of Methyl Orange (MO) and gaseous formaldehyde (HCHO). The degradation rates of MO and HCHO by optimized composite BT-0.6 were 97% and 60% respectively. The p-type BiOBr with narrow band gap can effectively improve the visible light absorption, and its p-n heterojunction with TiO 2 can significantly improve the separation efficiency and transfer rate of photogenerated electron hole pairs. Meanwhile, multi-dimensional nanoflower structure is not only conducive to light reflection and improve light utilization, but also can expose more catalytic active sites. This p-n heterojunction composite material can be used as a new and promising catalyst for environmental applications.

Retraction Note: Experimental and theoretical investigations on the spinel structure of Co2O3 nanoparticles synthesized via simple co-precipitation method

Retraction Note: Experimental and theoretical investigations on the spinel structure of Co2O3 nanoparticles synthesized via simple co-precipitation method

Maleic Anhydride-β-Cyclodextrin Functionalized Magnetic Nanoparticles for the Removal of Uranium (VI) from Wastewater

New maleic anhydride-β-cyclodextrin functionalized magnetic iron oxide nanoparticles (IONPs@MAH-β-CD) were prepared through the simple chemical coprecipitation method. Macroscopic batch experiments were carried out to study its absorption behavior for uranium (VI) under different environmental conditions. Using the magnetic separation technique, it was possible to easily separate IONPs@MAH-β-CD from uranium-containing wastewater. The equilibrium for uranium (VI) adsorption was reached for 180 min. The results showed that the kinetics and isotherm of the adsorption process were consistent with the pseudo-second-order kinetic model and Langmuir model, respectively, indicating that it was a chemisorption process. Compared with pure IONPs, the maximum adsorption quantity of maleic anhydride-β-cyclodextrin-coated iron oxide nanoparticles for uranium (VI) was significantly improved, which could reach 163.93 mg g−1. The recyclability of the IONPs@MAH-β-CD was investigated, and FTIR and XPS characterization were used to explore the possible mechanism of U(VI) adsorption.

Tuning the Fe/Co ratio towards a bimetallic Prussian blue analogue for the ultrasensitive electrochemical sensing of 5-hydroxytryptamine

Lack of highly efficient, inexpensive, and easily available catalysts severely limits the practical applicability of electrochemically sensing assay towards 5-hydroxytryptamine (5-HT). Herein, four kinds of Fe–Co bimetallic Prussian blue analogues (FeCo–PBAs) with different molar ratios of Fe to Co were prepared using a simple coprecipitation method. Interestingly, Fe(III) in K3 [Fe(CN)6] can be reduced to Fe(II) by adding trisodium citrate dehydrate, which could offer a new clue to synthesize PBAs with Fe(II) core ions. With the optimizational FeCo-PBA synthesized at a 0.5/1 M ratio of Fe to Co as an electrocatalyst, the constructed sensor shows excellent comprehensive performance for the 5-HT assay with a high sensitivity of 0.856 μA μM−1 and an ultralow detection limit of 8.4 nM. Under the optimum conditions, linearity was obtained in the ranges of 0.1–10.0 μM and 10.0–200.0 μM and preferable recoveries ranged from 97.8% to 103.0% with relative standard deviation (RSD) < 4.0%. The integrated properties of FeCo-PBA can be comparable to previously reported electrocatalysts for the 5-HT assay including noble metal-based and expensive carbon (graphene and carbon nanotubes)-based electrocatalysts. The proposed sensor also exhibits outstanding selectivity, reproducibility, and practicality for real sample analyses. This work is the first report on the PBA-based sensor for the 5-HT assay, verifying the practicability of this high-performance sensor for the 5-HT assay.

Enhanced silicate remediation in cadmium-contaminated alkaline soil: Amorphous structure improves adsorption performance

Silicates have been used as soil heavy metal passivators, but low remediation efficiency limited their development. In order to solve this problem, in this paper, an economical and environmentally friendly amorphous iron silicate was prepared by a simple co-precipitation method. It could be proved from the passivation experiments that the remediation efficiency of amorphous iron silicate (AIS) on Cd-contaminated soil was better than that of natural silicates (montmorillonite and diatomite), which reflected the superiority of amorphous materials. Plant experiments showed that AIS could effectively inhibit the absorption and accumulation of Cd2+ in the edible parts of garlic. In addition, it may effectively reduce the potential ecological risk assessment of soil, and its immobilization mechanism of Cd2+ includes electrostatic adsorption, co-precipitation, ion exchange, and complexation of surface functional groups. This study demonstrates the advantages of amorphous iron silicate as a new functional material in the remediation of Cd-contaminated soil and provides a reference for the development and application of environment-friendly passivators.

Synthesis of efficient, reusable, biomorphic hierarchical MgAlLa mixed metal oxides for removal of fluoride ions

AbstractAs an easily available layered double hydroxides (LDHs), hydrotalcites show significant effect in the adsorption of various ions in wastewater. It is worth noting that the calcined products (LDOs) of LDHs as adsorbents have the advantages of large specific surface area, low cost, renewable and non‐toxic to the environment. Herein, sustainable, efficient, biological, and hierarchical structure MgAlLa mixed metal oxides using catkins as a template (BC‐LDOs) are reported. A facile synthetic approach was presented for hierarchical MgAlLa layered double hydroxides via the simple coprecipitation method followed by a subsequent calcination at 550°C for 3 h. BC‐LDOs were characterized with IR, XRD, SEM, TEM, and BET and were studied for their adsorption performance of fluoride. The results showed that high‐specific surface area of BC‐LDOs is 118.02 m2/g, which is 10 times higher than that of MgAlLa mixed metal oxides without template (MgAlLa‐LDOs). BC‐LDOs had the best adsorption effect at pH 4–5 and the removal efficiency could reach more than 98%. In the experimental results involved in the study, the maximum adsorption capacity is 33.15 mg/g. In addition, the adsorption process of fluoride ions conformed to the pseudo‐second‐order model and the Freundlich model. Furthermore, the synthesized BC‐LDOs were recyclable and still exhibited good adsorption effect after 5 times of regeneration. The innovation of this study lies in the introduction of multi‐fiber catkins. There is no report on the introduction of catkins into LDHs in relevant studies. Hence, BC‐LDOs have a broad application prospect in the treatment and adsorption of fluoride‐containing wastewater.

Enhanced Photo-Fenton Activity Using Magnetic Cu0.5Mn0.5Fe2O4 Nanoparticles as a Recoverable Catalyst for Degrading Organic Contaminants

Interest in using various nanoparticle catalysts to activate H2O2 with light for organic contaminant and wastewater treatment is steadily increasing. We successfully synthesized magnetically recoverable Cu0.5Mn0.5Fe2O4 nanoparticles using a simple co-precipitation method followed by melamine-assisted calcination. Material characterization revealed that melamine acted as a coordinating agent during the calcination process that promoted a ferrite structure. Copper (Cu)-substitution effectively decreased material aggregation and promoted catalytic activities. Cu0.5Mn0.5Fe2O4 nanoparticles showed outstanding catalytic performance on several organic contaminants (87.6–100.0% removal within 2 h). Using oxytetracycline (OTC) as a surrogate wastewater constituent, we found that the hydroxyl radical (•OH) and superoxide anions (•O2−) were the active radical species involved in OTC degradation. Cu0.5Mn0.5Fe2O4 nanoparticles exhibited excellent photo-Fenton catalytic ability in real wastewater and demonstrated high material stability, even after four consecutive uses (i.e., fourth cycle). In a pilot-scale experiment (10 L), we provide proof that our rigorous treatment system was able to remove remnant OTC, TOC, and also any available colloidal particles to only 1 NTU. Ecotoxicity studies using an aquatic plant (Hydrilla verticillata) and zooplankton revealed that treated water could be reused in various ratios. Furthermore, at 5% of treated water, rapid leaf recovery and a significant increase in rotifer numbers were reported. These observations support the use of Cu0.5Mn0.5Fe2O4/H2O2/light as an efficient and environmentally friendly catalytic system for treatment of organic contaminants, and a radical generating mechanism is proposed.

Synchronously constructing the optimal redox-acidity of sulfate and RuOx Co-modified CeO2 for catalytic combustion of chlorinated VOCs

CeO2-based catalysts are highly active but easily deactivated for the catalytic combustion of chlorinated VOCs (CVOCs), and enhanced redox and acidity are also considered to be effective strategies. However, the screening of practicable modifiers and their preparation method to achieve the promotion and balancing of redox-acidity is still desired. In this work, sulfate and RuOx were simultaneously introduced into CeO2 by a simple co-precipitation method, and the optimal redox-acidity was constructed. The catalytic combustion of 1,2-dichloroethane (DCE) indicated that 2.5Ru-CeO2-S0.05 presented an outstanding oxidation activity and selectivity of chlorinated byproducts and superior cycle and long-term stability (at least 60 h at 280 °C), even in the presence of 5 % H2O. A series of control experiments, such as the introduction methods, the precursors and contents of Ru and sulfate, and their property characterization revealed that the bulk doping of Ru mainly contributed to the promoted activity and durability through more exposed Ce3+/4+ and oxygen vacancies and the rapid removal ability of the inorganic chlorine species via a semi-Deacon reaction pathway, as well as to the formation of chlorinated byproducts. Meanwhile, the synchronous introduction of sulfate as Brønsted acid sites efficiently inhibited these chlorinated byproducts, while its retained redox ability and the enhanced Lewis acid sites owing to the strong electron withdrawing of the sulfate also further promoted DCE oxidation. Moreover, 2.5Ru-CeO2-S0.05 showed a high activity and excellent durability for the catalytic oxidation of ethylene, vinyl chloride and their mixtures with 1,2-DCE. This work provided a demonstration for balancing the oxidation performance and acidity of CeO2-based catalysts, which contributed to the development of applicable catalysts for catalytic oxidation of CVOCs under actual working conditions.

Effect of Chelating Agents on the Structural, Optical, and Dye-Degradation Properties of Tungsten Oxide Nanoparticles

A simple co-precipitation method was used to create pure tungsten oxide (WO3) nanoparticles using phthalic acid, citric acid, and oxalic acid as chelating agents. The influences of chelating agents on the structural, morphological, and optical properties were investigated. X-ray diffraction (XRD) patterns of WO3 nanoparticles showed the existence of combined phase of anorthic-monoclinic for all the samples, and the crystalline size was found to be reduced while using oxalic acid. The vibrational band observed in the region around (500–800 cm−1) in the FTIR spectra indicates the formation of WO3 nanoparticles. SEM images revealed the formation of WO3 agglomerates. The energy-dispersive X-ray (EDX) spectra of the WO3 nanoparticles confirmed the purity of synthesized nanoparticles. The enhanced light-absorption ability of oxalic-acid-assisted WO3 nanoparticles are inferred from the decreased band gap energy in UV–vis absorption spectra. The PL spectra showed emission in both the UV and visible regions. The optimized reaction parameters for obtaining high catalytic efficiency are identified by varying the concentrations of oxidant, catalyst, and dye during the catalytic reaction. The synthesized WO3 nanoparticles exhibited better catalytic degradation of CV than MB and RB dyes even with the lesser quantity of catalyst material.

Green and facile synthesis of strontium doped Nb2O5/RGO photocatalyst: Efficacy towards H2 evolution, benzophenone-3 degradation and Cr(VI) reduction

A simple co-precipitation method has been developed to synthesize Nb2O5/reduced graphene oxide nanocomposite (NbO/RGO). The effect of various % of strontium doping on NbO/RGO was studied. The characterization results for its structure; morphology confirms the decoration of NbO with RGO followed by Sr doping resulting in Sr@N/R-wt% nanocomposite. Various % of Sr has been doped to NbO/RGO and evaluated for photocatalytic H2 evolution, degradation benzophenone-3, and Cr(VI). Enhanced H2 evolution was observed in Sr@N/R-0.75% nanocomposite (1925 μmol) and found three and two times greater than pristine NbO and NbO/RGO, respectively. Sr@N/R-0.75% nanocomposite was able to degrade 94.6 and 87.7% of BP and Cr(VI) respectively.

Highly efficient photocatalytic degradation of malachite green dye over copper oxide and copper cobaltite photocatalysts under solar or microwave irradiation

• Copper oxide and Copper Cobaltite have been successfully synthesized using Co-precipitation method. • Both prepared oxides show efficient photocatalytic activity in the degradation of malachite green dye under solar or microwave irradiation. • Photocatalyst amount and dye concentration significantly affected the rate of MG photodegradation. Advanced Oxidation Processes (AOPs) have been developed in the field of environmental technologies. The aim of this study was to verify the efficiency of heterogeneous photocatalysis in the AOPs for the degradation of organic pollutants. The photocatalytic degradation processes were carried out under sunlight and microwave irradiation in remediation of malachite green (MG) dye taken as model organic pollutant. The copper oxide and copper-cobalt bimetallic oxide (Cu-500 and CuCo-500) were prepared by a simple coprecipitation method and calcined at 500 °C. The synthesized photocatalysts were characterized by X-ray diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy coupled with Energy Dispersive X-ray spectroscopy (SEM-EDX), and Diffuse Reflectance Spectroscopy (DRS) analysis for optical properties (band gap of 1.49 and 1.44 eV for Cu-500 and CuCo-500, respectively). Thereafter, the catalytic activities of the prepared photocatalysts for MG photodegradation were investigated. The influence of different parameters on the photocatalytic reactions, such as photocatalyst mass, initial dye concentration, and irradiation source, was studied. The results reveal the efficiency of the synthesized photocatalysts in the photodegradation of MG with higher rate and good reusability. Hence, the monometallic Cu-500 photocatalyst exhibited better catalytic performance compared to bimetallic CuCo-500.

Construction of the composites of nitrogen and sulfur-doped porous carbon and layered double hydroxides and the synergistic removal of heavy metal pollutants

• High dispersion and stable attachment of LDH on nitrogen and sulfur doped porous carbon (NSPC). • The synergistic effect of LDH and NSPC enhances the adsorption of heavy metal ions. • The adsorption mechanism was attributed to surface complexation. Layered double hydroxides (LDHs) composites (NSPC@LDH) were successfully prepared on nitrogen and sulfur-doped porous carbon (NSPC) by a simple co-precipitation method. The synergistic effect between the modified porous carbon and LDH enhanced its adsorption performance. Compared with pure LDH, the composite had a larger specific surface area (188.78 m 2 /g) and pore structure with a smaller crystallite size (4.56 nm). The porous carbon carrier effectively mitigated the aggregation effect of LDH. The maximum adsorption capacities of NSPC@LDH for Zn 2+ (100 ppm) and Cu 2+ (100 ppm) were 125.7 mg/g and 137.5 mg/g, respectively, which were 2.85 and 2.39 times the original LDH. The XRD and XPS studies of the adsorbent after adsorption revealed that surface complexation and physical adsorption played a dominant role in the removal of Zn 2+ and Cu 2+ , and the introduction of N, S heteroatoms provided more active centers for heavy metal ions. Moreover, after five desorption cycles, NSPC@LDH still exhibited high removal efficiency. The results indicated that the synthesized NSPC@LDH composites have great potential for removing Zn 2+ and Cu 2+ from aqueous solutions.

Effect of Ni content, temperature on the electrical and colorimetric properties of nano NixZn(1-x)O blue pigments

Nanosized Ni doped ZnO (NixZn1-xO, with 20 ≤ × ≤ 70) were synthesized by simple coprecipitation method at different calcinations temperature (400, 600, 800 and 1000 o C). All synthesized oxides well characterized by XRD, scanning electron microscopy (SEM). The electrical properties and the colorimetric parameters (CIEL L* a* b*) were measured. The results obviously show that Ni2+ ions incorporated into the ZnO structure without difficulty. For the highest concentration of Ni2+ for x = 0.40 and 0.70 of Ni2+ doping, the XRD revealed an extra diffraction peak characteristic to NiO, indicating an upper limit of Ni concentration. The crystallite size was discovered to be between 13 and 109 nm. With the addition of Ni to the ZnO, the temperature dependency of electrical conductivity of samples increases. The temperature dependence of dielectric constant of samples is found to decrease with incorporation of Ni in the solution. The samples show very good blue color with load 20% of Ni.

Synthesizing Ag2Ox(3 wt%)-loaded ZnFe2O4 photocatalysts for efficiently saving polluted aquatic ecosystems

Herein, we report an Ag2Ox (3 wt%)-loaded ZnFe2O4 photocatalysts synthesized by co-precipitation and incipient wet impregnation approach for acetamiprid degradation, antibacterial, antioxidant, and toxicity assay. Initially, bare ZnFe2O4 nanostructures were made through a simple co-precipitation method. In the second step, 3 wt% of various transition metal oxides (CuOx, ZrOx, and Ag2Ox) were embedded on the surface of ZnFe2O4 photocatalysts via a wet impregnation method. Further, the prepared photocatalysts were systematically characterized using XRD, FTIR, FE-SEM, BET, HRTEM, and XPS analysis. The optimum Ag2Ox (3 wt%)-loaded ZnFe2O4 photocatalysts revealed higher degradation efficiencies for acetamiprid under sunlight irradiation. Additionally, the Ag2Ox (3 wt%)-loaded ZnFe2O4 photocatalysts showed more effective antioxidant and antibacterial activity than blank and bare ZnFe2O4 nanomaterials. The enriched catalytic efficiency can be accredited to the 3 wt% of Ag2Ox NPs loaded on ZnFe2O4 nanomaterials, possibly due to the boosted transport properties of the electron-hole pairs. This study will provide a new avenue for the development of simple and effective photocatalysts for efficiently saving polluted aquatic ecosystems.

Formation of CuO nanostructures via chemical route for biomedical applications

In this report, we have successfully prepared the CuO nanostructure by simple and cost-effective co-precipitation method by varying the concentration of precursor’s solution. The variation of concentration and its effect on the physico-chemical properties of the CuO nanostructure was investigated and discussed in detail. The structural, surface morphological, elemental composition, particle size with zeta potential, optical properties and surface area of the CuO nanostructures were characterized by X-ray diffraction (XRD), Fourier transform infrared analysis (FT-IR), Scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDAX), Dynamic light scattering (DLS), UV–Visible spectroscopy and BET analysis respectively. The XRD confirms the phase formation of the pure CuO and observed the monoclinic crystal structure of CuO nanostructure. Also, the surface morphology was studied by using SEM and it showed the petals like morphology and change in the aspect ratio of the nanostructure was observed when the concentration of precursors solution was altered. The surface area and porosity of the CuO nanostructures have been carried out and it reveals a more porous structure. Furthermore, the nanostructures are utilized for study of the antimicrobial properties. It is observed that CuO nanostructures shows enhanced antimicrobial properties towards B. subtilis, E.coli and E. faecalis and S. aureus bacteria. Also, we have studied the antifungal activity tested against C. albicans. Therefore, CuO nanostructures can be used as an ingredient for dermatological applications in creams, lotions, ointments, or other biomedical applications for human beings.

Effect of doping cation on the adsorption properties of hydroxyapatite to uranium

Hydroxyapatite samples doped with different metal ions (HAP-M, M ​= ​Cu, Sr, Al, Ce, and Ti) were successfully prepared by a simple co-precipitation method for effective U(VI) uptake. The applications of HAP-M in capturing U(VI) were investigated. Besides, numerous characterizations were taken to study the chemical and physical properties of HAP-M. The critical factors affecting U(VI) adsorption were examined, such as pH, contact time, initial concentration of U(VI) and solution temperature. The present study revealed that the adsorption effect of HAP for U(VI) can be affected by doping metal cations with different ionic radii, and HAP doping with Ti4+ ions increased its adsorption selectivity to U(VI). With the increase of the molar ratio of doped Ti4+ ions (5%–20%), the adsorption selection of U(VI) on HAP-Ti is also gradually increasing. HAP-Ti is a potentially efficient adsorbent in removing U(VI) from radioactive solutions.

Development of zinc ferrite nanoparticles with enhanced photocatalytic performance for remediation of environmentally toxic pharmaceutical waste diclofenac sodium from wastewater

Diclofenac sodium is an anti-inflammatory drug commonly used to cure pain in various treatments. The remarkable potential of this pain-killer leads to its excessive use and, therefore, a persistent water contaminant. Its presence in aqueous bodies is hazardous for both humans and the environment because it causes the growth of harmful drug-resistant bacteria in water. Herein, we present a comparative study of the ZnO and ZnFe2O4 as photocatalysts for the degradation of diclofenac sodium, along with their structural and morphological studies. A simple co-precipitation method was used for the synthesis of ZnO and ZnFe2O4 and characterized by various analytical techniques. For instance, the UV–Vis study revealed the absorption maxima of ZnO at 320 nm, which was shifted to a longer wavelength region at 365 nm for zinc ferrite. The optical band gaps obtained from the Tauc plot indicated that the incorporation of iron has led to a decreased band gap of zinc ferrite (2.89 eV) than pure ZnO (3.14 eV). The metal-oxygen linkages shown by FTIR indicated the formation of desired ZnO and ZnFe2O4, which was further confirmed by XRD. It elucidated the typical hexagonal structure for ZnO and spinel cubic structure for ZnFe2O4 with an average crystallite of 31 nm and 44 nm for ZnO and ZnFe2O4, respectively. The micrographs obtained by SEM showed rough spherical particles of ZnO, whereas for ZnFe2O4 flower-like clustered particles were observed. The photocatalytic investigation against diclofenac sodium revealed the higher degradation efficiency of ZnFe2O4 (61.4%) in only 120 min, whereas ZnO degraded only 48.9% of the drug. Moreover, zinc ferrite has shown good recyclability and was stable up to five runs of photodegradation with a small loss (3.9%) of photocatalytic activity. The comparison of two catalysts has suggested the promising role of zinc ferrite in wastewater remediation to eliminate hazardous pharmaceuticals.

High-valence metal doped Co2FeAl alloy as efficient noble-metal-free electrocatalyst for alkaline hydrogen evolution reaction

Most efficient electrochemical hydrogen evolution reaction (HER) catalysts in alkaline solutions are based on precious metals, whose rarity and high cost are severely limiting their large-scale applications. In this work, we synthesized Mo-doped and W-doped Co2FeAl alloys by a simple coprecipitation method. The HER in alkaline solution is promoted through the synergistic effect of thermal annealing and doping of high-valence metal atoms. Thermal annealing could optimize the surface morphology and improve the crystallinity. In the meantime, the doping of high-valence metal atoms could further regulate the crystal structure and electronic structure of alloys. Therefore, annealing temperatures and doping concentrations have a marked impact on the catalytic performance. In particular, when the Mo doping concentration is 27 at% and the annealing temperature is 750 ℃, the synthesized Co2FeAlMo1.5 (750 ℃) alloy electrocatalyst exhibits the superior HER performance in alkaline media. It displays a low overpotential of only 71 mV at 10 mA cm−2 and a Tafel slope of 110 mV dec−1. An excellent stability is also demonstrated that the electrocatalyst can work stably for 20 h and the overpotential is only shifted by 2 mV after 1000 cycles. A series of characterization tests indicate that the crystal structure and electronic structure of Co2FeAlMo1.5 (750 ℃) are optimized, which can improve the catalytic activity and promote alkaline HER. This work provides a new strategy for improving the catalytic performance of non-noble metal electrocatalysts for alkaline HER.