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•Green synthesis of ZnO nano-crystals using Chenopodium album leaf.•Characterization of ZnO nano-crystals by XRD, TEM, FTIR, SEM, Raman, EDEX, UV–Visible.•The broad size distribution ...of nano-crystals and substantial improvement in crystalinity after annealing the sample .•Antibacterial activity test of ZnO nano-crystals on Escherichia coli and Staphylococcus aureus microorganisms.•A novel way of synthesizing functional materials for various applications.
We present an effective, simple and eco-friendly method for the green synthesis of ZnO nano-crystals. An aqueous extract of Chenopodium album leaf was used as a biological reducing agent for the fabrication of ZnO nano-crystals from the zinc sulphate heptahydrate. The as-prepared and annealed powder samples were characterized using advanced techniques. The results confirmed the presence of ZnO crystals with a broad size distribution, whose crystallinity was noticed to improve substantially after the annealing. Further, in antibacterial activity test of ZnO nano-crystals performed on Escherichia coli and Staphylococcus aureus microorganisms, inhibitory effect was found to increase with concentration. Compared to Gram-positive bacteria, ZnO nano-crystals showed more resistance to Gram-negative bacteria. This green synthesis route of ZnO nano-crystals is novel and aims to reduce the use of toxic chemicals in fabricating the nanoparticles of functional oxides, which have a wide range of potential applications in general and biomedical science, in particular.
ZnO crystals are employed in numerous industries, but precisely controlling their morphologies is still challenging. In this work, a continuous flow process for synthesizing ZnO crystals is developed ...based on the co‐precipitation method. ZnO crystals at different morphologies, including needle‐like, rod‐like, flower‐like, spindle‐like, and nanospheres, are successfully prepared at low temperature. The influence of reaction temperature, pH value, ZnCl2 feeding concentration, and reaction time on the morphology, size, and purity of ZnO crystals is systematically investigated. The results of X‐ray diffraction show that the high‐purity ZnO can only be produced when the reaction temperature is above 75 °C. The band gap energies of ZnO evaluated by UV–vis diffuse reflectance spectroscopy increase with the synthesis temperature. According to scanning electron microscope (SEM) findings, the size of ZnO crystals is regulated by controlling the reaction time. Interestingly, the morphology of ZnO crystals is changed from 1D to 3D structure by controlling the feeding concentration of ZnCl2. Moreover, a concentration difference mechanism of ZnO crystal morphology evolution is proposed by monitoring the real‐time concentration of free Zn2+ ions.
This article reports a low‐temperature continuous flow process based on co‐precipitation for synthesizing ZnO crystals, including needle‐like, rod‐like, flower‐like, spindle‐like, and nanosphere ZnO crystals. It is found that the morphology of ZnO changes from a 1D to a 3D structure when the reactant concentration varies, revealing the mechanism of the morphological evolution of ZnO experimentally.
To acquire the direct time response of ZnO crystals to high energy particles, a dual-channels single photon correlation (DCSPC) system based on the measurement of the autocorrelation function of the ...fluoresce temporal profile was employed. The measuring resolution of the DCSPC system calibrated by Cerenkov luminescence is 46 ps. With this DCSPC system, the fast decay time constants of ZnO:Ga, ZnO:In and ZnO:Sc under charged particle alpha and beta excitation were successfully measured, which are 1.56 ns, 0.48 ns, 0.12 ns, and 1.11 ns, 0.40 ns, 0.10 ns, respectively . For all the three samples, it is found that the decay time constants under beta excitation are faster than those under alpha excitation, indicating that ZnO crystal is a fast scintillation material with pulse shape discrimination (PSD) ability. This would be applied in selective detection of mixed radiation field, particularly where high counting rate is required.
ZnO materials with a range of different morphologies have been synthesized via a simple solvothermal method in dimethylacetamide (DMAc) media. DMAc was used as the base source and solvent in such ...solvothermal syntheses for the first time. The effect of the DMAc content in the solvothermal process on nucleation, growth, and the final morphology of the ZnO nanostructures was investigated. XRD results revealed that single-phase ZnO with the wurtzite crystal structure was obtained for different DMAc contents in solution. X-ray photoelectron spectroscopy confirmed high purity of the as-prepared ZnO crystals. SEM imaging showed that ZnO with spherical shapes, dumbbell, and rod-like were synthesized by controlling DMAc content. In addition, vibrational properties of ZnO crystals with different morphologies were investigated by Raman spectroscopy. The optical properties of the as-prepared ZnO materials were investigated by UV–vis absorption and room temperature photoluminescence. The possible mechanism was also proposed to account for the growth of the ZnO crystals in the DMAc solvent.
We report on C-doped ZnO, with different weight percentages of dopant, prepared by a high-energy ball milling method. The annealing conditions with temperature of 800°C and in argon environment ...appear to be the optimal conditions for producing good quality crystals as well as pure UV emission. XRD and FTIR analysis indicate the substitution of C for Zn. In addition, Raman spectroscopy suggests a disordered graphitic layer covering the crystals. Photoluminescence investigation reveals the continuous quenching of visible region upon increasing C concentration and the intensity ratio between defect-related and UV emission can be as negligible as 0.02. The passivation of surface defects and the creation of a non-radiative recombination pathway by carbon integration are proposed as possible origins of the suppression.
•Carbon doping by a ball-milling method to suppress visible emission in ZnO crystals.•The optimal annealing conditions to achieve the suppression.•Investigate the structure of C-doped ZnO by XRD, FTIR, PL, and Raman measurements.
•The low-cost lignin waste was reused.•Calcium lignosulfonate (CLS) and sodium dodecyl sulfonate (SDS) as surfactant were used.•The ZnO samples were synthesized by eco-friendly liquid precipitation ...method.•The obtained ZnO photocatalyst showed high UV and sun light photocatalytic activities for MB.
ZnO crystals with block and net structures were successfully prepared using liquid precipitation method in aqueous solutions with the presence of with calcium lignosulfonate (CLS) and sodium dodecyl sulfonate (SDS). X-ray diffraction, scanning electron microscopy and UV–vis absorption spectroscopy and other modern testing techniques were employed to characterize the structure, morphologies and properties of the as-prepared ZnO samples. The obtained crystals exhibited the crystal structure of wurtzite ZnO, while the morphologies is completely different with the increasement of SDS. The morphologies and performances were infected by the SDS, which were suggested on the basis of analytical results. The as-prepared ZnO nanocomposites with 2g of CLS and different amount of SDS (ZLS) had good adsorption performance, and displayed excellent photocatalytic activity in the degradation of methylene blue (MB). Adsorption efficiency of the ZLS-0.005 is 49.36% after 30min in dark condition to reach the adsorption-desorption equilibrium of dye MB. It can be seen that the degradation efficiency for MB catalyzed by ZLS-0.015 is 98.99% within 60min under UV light and 98.25% within 120min under sunlight.
A novel immobilization platform has been developed for fabricating enzyme-based biosensors of direct electrochemistry by synergistically using ZnO crystals and nano-sized gold particles (Nanogold). ...ZnO crystals were synthesized with flower-like structure to be casted on the electrode mediated by chitosan so as to provide larger surface area for anchoring horseradish peroxidase (HRP)-labeled Nanogold. The resultant enzyme biosensor was tested for the determination of H
2O
2 as a model of test system. Experimental results showed that HRP could be immobilized onto the nanocomposite matrix with high loading amount and well-retained bioactivity. Moreover, rapid and direct electron transferring could be achieved between the enzyme’s active sites and the electrode surface, thus facilitating the direct electroanalysis of H
2O
2. The developed enzyme sensor can directly determine H
2O
2 in the concentration range from 1.5
×
10
−6 to 4.5
×
10
−4
M, with a detection limit of 7.0
×
10
−7
M. High detection reproducibility can be additionally expected. Such an enzyme immobilization platform of ZnO–Chitosan/Nanogold should hold great promise for the development of the enzyme biosensors of direct electrochemistry.
► Lignin used in the synthesis is recovered from the pulping black liquor. ► After modification, lignin was applied to fabricate ZnO. ► ZnO was prepared by direct precipitation without sintering. ► ...The synthesized ZnO nanocrystallites show a hexagonal wurtzite structure. ► There are an abundance of mesopores on prepared ZnO.
The surfactant of lignin-phosphate quaternary ammonium salt (LPQAS) has been synthesized from chemical conversion of the alkali lignin that is a byproduct of the pulp industry. Using this lignin-based LPQAS, the wurtzite-structure ZnO crystals with plenty of mesopores can be prepared through one step reaction in aqueous solution. These fine hexagonal ZnO particles have been confirmed by X-ray diffraction (XRD) and their diameters have been calculated to be within 20 and 40nm using the Debye–Scherrer equation. It is shown from our SEM results that the mole ratio of Zn2+ and OH− ions affects the morphology of ZnO. And at a mole ratio of 1:10 for the Zn2+ and OH− ions, the flower-like ZnO nanomaterials were obtained. Both TEM and Brunauer–Emmett–Teller (BET) determinations reveal that as-prepared ZnO crystallites contain abundant mesoporous structures. A possible formation mechanism of these mesoporous ZnO crystallites has been proposed in this work. Finally, photoluminescent spectra of the synthesized ZnO were measured at room temperature, exhibiting two characteristic bands of typical ZnO materials at 383nm (sharp) and in the range of 480–600nm (broad).
We report on square-shape distribution of ZnO crystals in glass by simultaneous femtosecond laser irradiation at multiple spots with the application of a spatial light modulator. Raman spectra and ...Raman mapping were used to characterize the formation of ZnO crystals and distribution of ZnO crystals, respectively. The shapes of the laser-modified region and the distribution of ZnO crystals were compared between the cases of one spot irradiation and multiple spot irradiation. The elemental distributions of the laser-modified region were investigated by an Electron Probe Microanalyzer.
•Square-shape distribution of ZnO crystals in glass was achieved.•The elemental distributions of Zn2+ agree well with square-shape distribution of ZnO crystals.•This method may provide a new way for spatial control of fs laser induced crystallization.
