Flower-like ZnO Nanostructures Research Articles

Hydrothermal Synthesis of ZnO Nanoflowers: Exploring the Relationship between Morphology, Defects, and Photocatalytic Activity

Two forms of flower-like ZnO nanostructures were synthesized using hydrothermal methods at various growth times/temperatures and zinc precursors. The morphology, structure, chemical composition, and optical properties of these ZnO nanoflowers were studied using a scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD), X-ray photoelectrons spectroscopy (XPS), Raman spectroscopy, and UV–Vis spectroscopy. The SEM images revealed two forms of flower-like nanostructures, namely lotus- and tulip-like flower ZnO nanostructures. The XPS analysis revealed the oxidation state of the Zn and O elements, as well as the presence of OH groups on the surface of the lotus-like flower ZnO nanostructure. The XRD results revealed less crystallinity of the lotus-like ZnO nanoflowers (NFs) compared with the tulip-like ZnO NFs. The XRD results revealed the presence of Zn (OH)2 in the ZnO NFs. The Raman results confirmed less crystallinity of the lotus-like ZnO NFs. The estimated optical bandgap was 2.92 and 3.0 eV for the tulip- and lotus-like ZnO NFs, respectively. The tulip-like ZnO NFs showed superior photocatalytic degradation of methylene blue dye, verified via UV–Vis radiation, compared with the lotus-like ZnO NFs, which show the impact of the structure defects and OH- impurities on the photocatalytic performance of ZnO nanoflowers.

Doping effect of Europium (Eu3+) on flower-like ZnO nanostructures: shape variations, optical properties and its applicability in electrochemical sensing of heavy metal (Lead) ion detection

Doping effect of Europium (Eu3+) on flower-like ZnO nanostructures: shape variations, optical properties and its applicability in electrochemical sensing of heavy metal (Lead) ion detection

Synthesis and Characterization of Flower-Like Cobalt-Doped ZnO Nanostructures for Ammonia Sensing Applications

Abstract The present study uses the co-precipitation method to explore the synthesis of zinc oxide and cobalt-doped ZnO sensors, encompassing a range of cobalt concentrations from 1 to 4 wt.%. The synthesized samples undergo comprehensive analysis to evaluate their structural, morphological, optical, and gas-sensing properties. X-ray diffraction revealed a hexagonal Wurtzite structure, and the crystallite size decreased from 16.92 to 15.39 nm. Energy-dispersive X-ray spectroscopy and Fourier-transform infrared spectroscopy collectively affirmed the presence of cobalt. Scanning electron microscopy was used to analyze the morphological characteristics. The Tauc-plot was used to determine the optical bandgap via diffuse reflectance spectroscopy. As cobalt doping increased, the band gap increased from 3.18 to 3.23 eV. Further, atomic force microscopy and Brunauer-Emmett-Teller analysis were used to assess the surface topography and pore size distribution. The AFM measurements indicated roughness within 435-700 nm. The BET analysis revealed mesoporous properties, with surface area ranging between 18.657 to 21.962 m2/g. Subsequently, the gas-sensing capabilities of the Co-doped ZnO sensors were examined for various volatile organic compounds at room temperature. The sensor with 4% Cobalt doping exhibited a fast response and recovery time of 21 and 20 seconds for 2 ppm of NH3

Electrochemical Performance of Flower-like ZnO Nanostructure Crystal for Supercapacitor Electrode Applications

straightforward, easy and low-cost process using cetyltrimethylammonium bromide (CTAB) as a templated sonochemical production method was used to prepare ZnO nanostructures with the appearance of flowers. The morphological characteristics of ZnO materials have a more significant impact on variables like the CTAB template and sonochemical reaction time. The advantage of the flower-like ZnO materials is the more active reaction centre, which improves redox processes and results in outstanding electrochemical attributes like greater specific capacitance, excellent rate capability and better cyclic stability. The specific capacitance of the flower-shaped ZnO nanostructures (ZnO-2) from the cyclic voltammetric (CV) analysis was found to be 425 F g–1 at a scan rate of 5 mV s–1 and the charge/discharge study renders the specific capacitance is 426 F g–1 at a current density of 1 Ag–1. After 3000 CV cycles at a scan rate of 100 mV s–1, 89% of the initial capacitance still was retained in the long-term cyclic stability analysis. The distinctive flower-like ZnO nanostructures can be extended more for supercapacitor device applications.

Flower-like ZnO Nanostructures Local Surface Morphology and Chemistry

This work presents the results of comparative studies using complementary methods, such as scanning electron microscopy (SEM), X-ray photoemission spectroscopy (XPS), and thermal desorption spectroscopy (TDS) to investigate the local surface morphology and chemistry of flower-like ZnO nanostructures synthesized by the thermal oxidation technique on native Si/SiO2 substrates. SEM studies showed that our flower-like ZnO nanostructures contained mostly isolated and irregular morphological low-dimensional forms, seen as rolled-up floss flowers, together with local, elongated, complex stalks similar to Liatris flowers, which contained joined short flosses in the form of nanodendrites. Beyond this, XPS studies showed that these nanostructures exhibited a slight surface nonstoichiometry, mostly related to the existence of oxygen-deficient regions, combined with strong undesired C surface contamination. In addition, the TDS studies showed that these undesired surface contaminations (including mainly C species and hydroxyl groups) are only slightly removed from the surface of our flower-like ZnO nanostructures, causing an expected modification of their nonstoichiometry. All of these effects are of great importance when using our flower-like ZnO nanostructures in gas sensor devices for detecting oxidizing gases because surface contamination leads to an undesired barrier for toxic gas adsorption, and it can additionally be responsible for the uncontrolled sensor aging effect.

Optical Properties of Hydrothermally Grown ZnO Nanoflowers

Abstract: A simple hydrothermal method has been successfully employed to synthesize flower-like ZnO nanostructure. X-ray diffraction data confirm the formation of ZnO with a Wurtzite structure. FESEM images show the flower-like morphology of the synthesized nanostructures. The energy dispersive X-ray spectroscopic analysis confirms the stoichiometric composition.. X-ray fluorescence spectrum shows no impurity element in the synthesized ZnO. The synthesized ZnO exhibits low absorption in the visible region of wavelength. Band gap enhancement was also observed owing to the quantum confinement effect. The synthesized ZnO nanoflowers exhibit strong room-temperature photoluminescence with a broad emission peak at 429 nm arising due to the recombination of electrons at zinc interstitials and holes in the valence band. This defect-related photoluminescence is very important in the context of understanding the defect dynamics in ZnO. Background: Zinc oxide (ZnO) is a well-known multifunctional material possessing unique structural, electrical, and optical properties that are very useful in various device applications. Being a high and direct band gap semiconductor, it is potentially being used in various UV light sources and detectors fabrication. However, the emission and absorption properties strongly depend on the size of the ZnO nanoparticles which in turn depends on the morphology of the nanostructure. Therefore, it is very much important to understand the structure-property relationship for a predictable device performance. Objectives: Our objective of this work is to synthesize flower-like ZnO nanostructures using a simple hydrothermal method. The flower-like ZnO morphology offers a large surface area that will be very suitable for designing gas and chemical sensor devices. Another objective of this work is to study the crystallography of ZnO. Next, the optical properties (emission and absorption) have been investigated to understand the defect-related photoluminescence mechanism. Method: A simple hydrothermal method has been deployed to synthesize flower-like ZnO nanostructures. A chloride decomposition scheme has been used to produce zinc hydroxide ions that will produce ZnO nuclide. At the onset of saturation, ZnO nanocrystals start to grow. The entire reaction was performed inside a Teflon cell stainless steel autoclave. The autoclave was placed in a horizontal tube furnace and maintained at 150 °C for 2 hr. resulting in the formation of white powder-like material. Results: The X-ray diffraction data confirm the formation of polycrystalline ZnO having a Wurtzite structure. Flower-like morphology was clearly observed in FESEM images. The EDS data confirm the composition of ZnO with proper stoichiometry. Gibb’s free energy calculation favors the reaction under the experimental condition. The absorption spectrum was used to calculate the band gap of the synthesized ZnO nanoflowers. The Tauc plot revealed the band gap of the synthesized ZnO to be~ 3.69 eV. This enhancement of band gap compared to bulk ZnO occurs due to the quantum confinement effect. The synthesized ZnO nanoflowers exhibit broad photoluminescence peaked at 429 nm owing to the presence of interstitial zinc. Conclusion: A hydrothermal method has been successfully used to synthesize well-crystalline ZnO nanoflowers of proper stoichiometry. The flower-like nanostructure exhibits band gap enhancement due to the quantum confinement effect. Room temperature visible photoluminescence was observed from the ZnO nanoflowers with a board emission peak at 429 nm. This emission arises due to the presence of deep-level zinc interstitial states. This finding will be very useful in understanding the role of defects in the visible emission from ZnO nanostructures.

Atomic layer deposition of Rh/ZnO nanostructures for anti-humidity detection of trimethylamine

The design of metal/semiconductor hybrid nanostructures is an important strategy for the development of efficient chemical gas sensors. In this paper, a highly sensitive gas-sensing material for trimethylamine (TMA) detection was designed by atomic layer deposition (ALD) of Rh onto ZnO flower-like nanostructures. The ZnO nanostructures consisted of porous nanosheets prepared by a hydrothermal method, and then functionalized with Rh catalysts to explore the sensing properties to TMA. The gas sensing investigations show that the loading of Rh has a remarkable influence on the performance of the sensors. The Rh/ZnO sensor with 10 cycles of Rh ALD showed the best response to TMA at 180 °C. A very high response of 11.3 was recorded when exposed to 10 ppm TMA, which is 3-times higher than that of pristine ZnO. Furthermore, the sensor also has a fast response-recovery and an excellent humidity resistance, as well as a low detection limit of 55 ppb, which suggest high potential for reliable detection of sub-ppm TMA.

Microstructural study and crystallite size analysis of chemically grown bougainvillea flower-like zinc oxide nanostructures

A simple wet chemical method has been utilized to synthesize Bougainvillea flower-like ZnO nanostructures. The morphology of the synthesized material was observed in field emission scanning electron microscope revealing the formation of flower-like nanostructures comprising of bunch of leafy patterns. X-ray diffraction (XRD) was used for structural analysis of the synthesized ZnO. The XRD pattern suggests the formation of pure ZnO nanostructures. Peak profile analysis was carried using the Scherrer method, Williamson-Hall method and uniform deformation model to study the effect of microstrain on the crystallite size.

Enhanced hydrogen sensing performances of PdO nanoparticles-decorated ZnO flower-like nanostructures

In this work, PdO nanoparticles-decorated ZnO flower-like nanostructures (PdO/ZnO) were synthesized by a one-step facile hydrothermal route and investigated their performance for hydrogen sensing applications. The structural and morphological characterizations were examined by XRD, FESEM, EDS, TEM, and XPS techniques and confirmed the homogenous decoration of PdO nanoparticles on the surface of ZnO flowers. UV-Vis spectroscopy and photoluminescence (PL) spectroscopy were used to investigate the optical characteristics. The ZnO and PdO/ZnO sensors were explored towards different target gases such as hydrogen (H2), carbon monoxide (CO), nitrogen dioxide (NO2), and ethanol. The concentration range of target gases was 2–100 ppm at an operating temperature range of 200–400 °C. It was concluded that PdO/ZnO flowers sensor showed high sensitivity, a speedy response time (20 s), and recovery time (960 s) towards H2 at 350 °C in comparison to the ZnO sensor. In addition, the PdO decorated ZnO flowers-based sensor showed high selectivity towards H2 against CO, NO2, and ethanol. This enhanced gas-sensing performance of the PdO/ZnO sensor has been attributed to the catalytic effect of PdO nanoparticles, and the formation of the PdO-ZnO p-n heterojunction, and their unique flower-like nanostructures. As a result, our research shows that coating PdO on ZnO flowers is an effective technique to improve hydrogen gas sensing performance and can be employed in various applications. The synergist impact of PdO nanoparticles, the arrangement of the PdO-ZnO p-n heterojunction, and their remarkable blossom-like nanostructures were the significant elements for improved gas-detecting execution of PdO/ZnO sensor.

Synthesis of super-hydrophobic CuO/ZnO layered composite nano-photocatalyst

The introduction of super-hydrophobicity into the field of photocatalysis has attracted the attention of many researchers nowadays. Here, CuO nanowires were synthesized via thermal oxidation method. The flower-like ZnO nanostructures were self-assembled with CuO nanowires by hydrothermal growth method. The functionalized super-hydrophobic CuO/ZnO layered composite nano-photocatalyst was obtained though polydimethylsiloxane (PDMS) grafting. We analyzed the effects of zinc sources, hydrothermal reaction time, solution concentration and surfactant concentration on the properties of the composite nano-photocatalyst. FESEM micrographs revealed CuO/ZnO layered composite nanostructures, which were composed of CuO nanowires with uniform morphology and carnation-like ZnO nanoflowers. XRD spectrum showed CuO/ZnO layered composite nano-photocatalyst possessed pure CuO phase and the wurtzite structure of ZnO. UV–vis spectrum manifested that the composite nanostructures had desired light absorption for ultraviolet light band and the contact angle (CA) results confirmed the successful modification of super-hydrophobic functionalization. After the modification of PDMS, the CuO/ZnO layered composite nano-photocatalyst prepared with the optimal conditions shows desired photocatalytic properties and super-hydrophobicity. The stable super-hydrophobic property after photocatalytic degradation is expected to improve self-cleaning and broaden the application field of photocatalyst.

A new method for synthesis of ZnO flower-like nanostructures and their photocatalytic performance

ZnO flower-like nanostructures have been successfully synthesized by a new and facile hydrothermal method. Their crystal structures and photocatalytic performance were also investigated. The amount of surfactant cetyltrimethyl ammonium bromide (CTAB) added to the precursor had an important effect on the ultimate morphology of the ZnO flower-like nanostructures. As the CTAB amount increased, the petals of the ZnO nanoflowers architecture changed from nanorods to nanosheets. In addition, for the nanoflowers assembled by nanosheets, the thickness of nanosheet can be controlled by adjusting the CTAB amount. The plausible growth mechanisms of the ZnO flower-like nanostructures were proposed. Furthermore, the nanosheets-assembled nanoflowers exhibited better photocatalytic performance than the nanorods-assembled nanoflowers toward Rhodamine B owning to their larger specific area and more OH groups absorbed on the nanosheet surface.

Growth of ZnO Nanoflower Arrays on a Patterned Sapphire Substrate

In this study, we investigated a novel technology to grow the ZnO nanoflower arrays on a patterned sapphire substrate using hydrothermal method. The process to prepare the substrate and grow ZnO nanoflower arrays were that the patterned concave sapphire substrates were cleaned using acetone, isopropyl alcohol, and D.I. water in an ultrasonic cleaner. Al sacrificial layer with the thickness of 600 nm was deposited using a thermal evaporation technology. The sol-gel process was used to deposit the ZnO seed layer on the patterned concave sapphire substrates, and then the ZnO seed layer was annealed at 500°C in Ar ambient for 1 h. The optical grade silicone A-B glue was coated on the ZnO seed layer and then the mixed solution of K3Fe(CN)6 : KOH : H2O = 10 g : 1 g : 100 ml was used to etch the sacrificial Al layer. (f) A lift-off technology was used to move the ZnO seed layer/silicone A-B glue to silicon substrate. Finally, a hydrothermal method was used to grow the ZnO nanorods on the ZnO seed layer/silicone A-B glue/silicon substrate at 90oC with the different durations of 10 to 60 min. Focused ion beam system (FIB) was used to observe the cross sectional morphology of patterned ZnO seed layer. The crystal structural of the flower-like ZnO nanostructures was analyzed using X-ray diffraction (XRD) pattern, the morphological of the flower-like ZnO nanostructures was observed using FIB and field emission scanning electron microscope (FESEM). Also, the optical properties of the flower-like ZnO nanostructures were investigated.

Phyto-reflexive Zinc Oxide Nano-Flowers synthesis: An advanced photocatalytic degradation and infectious therapy

Combating the limitations of chemical approach, a Phyto-reflexive surface decorated ZnO nanoparticles were synthesis for enhanced activity against resistant infectious agent and toxic dyes. Flower-like ZnO nanostructure with average size of 30 nm and 25 nm using chemical method and Phyto-synthesised respectively. Prepared ZnO nano-flowers have been characterised by UV (UV–visible spectrometry), XRD (X-ray Diffraction), TEM (Transmission Electron Microscopy), HRTEM (High Resolution Transmission Electron Microscopy) and EDS (Energy Dispersive X-ray Spectroscopy). Anti-bacterial activity against Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa , exhibited 78%, 88% inhibition for chemical prepared ZnO NFs and Phyto-reflexive surface modified ZnO NFs exhibited 85%, 94% compared to Ciprofloxacin. MIC (Minimum Inhibitory Concentration) values against S. aureus and P. aeruginosa of biological ZnO NFs, were calculated as 62.5 and 125 ug/ml and 125 and 250 ug/ml for chemically synthesized ZnO NFs respectively. Anti-fungal activity against Aspergillus niger and Candida Albicans showed 78%, 80% activity with chemically ZnO NFs and 91%, 100% inhibition with biologically ZnO NFs. Anti-oxidant potential determination revealed 56.5% and 67.8% activity at 50 mg/mL with chemical and biological ZnO NF respectively. Furthermore, Degradation of methylene blue (MB) using ZnO NFs up to 78% using chemically prepared and 90% using Phyto-reflexive ZnO NFs. Thus, the comparative analysis concluded, Phyto-reflexive surface modified synthesis of ZnO NFs improved infections activity against pathogens and photocatalytic activity for hazardous chemicals.

Enhanced Nitrogen Monoxide Gas-Sensing Performance of Ti-Doped ZnO Nanostructures By SILAR

Fig. 1. Schematic illustration of SILAR fabrication process [1].The use of semiconducting metal oxides to develop highly sensitive NO gas sensors remains an important approach in the field of gas sensing applications [2]. In this research, we describe the synthesis, characterization, and application of a very promissing NO gas sensing material ZnO doped with different atomic percentages of Ti and prepared by a simple SILAR [3] method. Synthesized specimens were structurally and morphologically characterized. The NO sensing characteristics of pristine ZnO and Ti-doped ZnO were compared using a gas sensing measurement system. The sensitivity, operating temperature, and response/recovery time were systematically investigated based on the change in electrical resistance of the materials in the presence of NO. Experimental results confirmed that 50 at% Ti-doped ZnO showed a maximum response to NO gas at an operating temperature. The sensing mechanism of the pristine and Ti-doped ZnO nanostructures is discussed in detail. We believe that the Ti-doped, flower-like ZnO nanostructure is a potential material for semiconductor-oxide-based NO gas sensors. Key words: NO gas sensor, SILAR method, flower-like, Ti-doped ZnO. Acknowledgement This research was supported by the research grant 021220FD2201 “Development of highly sensitive MOS based nano-film gas sensors” from Nazarbayev University. Reference [1] B. Soltabayev, M.A. Yıldırım, A. Ateş, S. Acar, The effect of indium doping concentration on structural, morphological and gas sensing properties of IZO thin films deposited SILAR method, Mater. Sci. Semicond. Process. 101 (2019) 28–36. https://doi.org/10.1016/j.mssp.2019.05.026.[2] V.S. Bhati, M. Hojamberdiev, M. Kumar, Enhanced sensing performance of ZnO nanostructures-based gas sensors: A review, Energy Reports. 6 (2020) 46–62. https://doi.org/10.1016/j.egyr.2019.08.070.[3] T. Çorlu, I. Karaduman, M.A. Yildirim, A. Ateş, S. Acar, Effect of Doping Materials on the Low-Level NO Gas Sensing Properties of ZnO Thin Films, J. Electron. Mater. 46 (2017) 3995–4002. https://doi.org/10.1007/s11664-017-5503-z. Figure 1

NO2 sensing properties of 3D flower-like ZnO nanostructure decorated with thin porous petals synthesized using a simple sol–gel drop-casting method

A three-dimensional flower-like ZnO nanostructured film decorated with the thin porous ‘petals’ is synthesized using an inexpensive sol–gel drop-casting method, and the NO2 detection characteristics of the nanostructured film are studied. The gas-sensing study shows higher sensitivity with selectivity toward NO2 gas, exhibiting good reproducibility and stability. The as-synthesized nanostructured 3D flower-like ZnO film shows excellent NO2 sensing performance, with a maximum gas response of 23.3 for 100 ppm NO2 gas at an operating temperature of 180 °C. A detailed gas-sensing study reveals that the enormous porous petals with various inter-connected pores fused on the flower-like ZnO nanostructure improve the adsorption of gas molecules; consequently, the synthesized ZnO nanostructure exhibits a superior level of NO2 gas-sensing activity. This study provides a promising path towards the development of a highly sensitive NO2 gas sensor and an easy way to fabricate the 3D morphology decorated with exceedingly porous ‘petals’.

Microwave assisted facile synthesis of 3D flower-like ZnO nanostructures for enhanced photocatalytic degradation/removal of Eosin Y from water

Three-dimensional ZnO nanoflower has been synthesized via microwave irradiation technique using glycine as complexing/capping agent for the first time. TEM, SAED, XRD, FTIR, UV and PL spectra have been recorded to characterize the synthesized ZnO nanostructures. The TEM image indicates the formation of 3D flower-like ZnO nanostructures having diameter ~0.74-1.60 μm. The spacing between adjacent lattice fringes obtained from the HRTEM image is 0.145 nm which indicated the presence of (103) lattice plane of ZnO. The synthesized ZnO nanoflower show excellent luminescence properties. The photocatalytic properties of synthesized ZnO nanoflower is depicted by the degradation of Eosin Y dye under solar irradiation. It is found that 98.9% of Eosin Y dye is degraded within 50 min under solar irradiation. Henceforth, ZnO nanoflower acts as an effective photocatalyst for the degradation of Eosin Y dye.

Design and construction of hierarchical α-Co(OH)2-coated ultra-thin ZnO flower nanostructures on nickel foam for high performance supercapacitors

Abstract Most pseudocapacitor materials have only near-surface parts participated into the Faradic-reaction, and their low contribution limits the development of pseudocapacitors. In this situation, hierarchical α-Co(OH)2-coated ultra-thin ZnO flower nanostructures on nickel foam (NF@ZnO@Co(OH)2) are designed and constructed to enhance the efficiency of charge and ion-transfer process as well as to improve the low contribution of pseudoactive materials during the Faradic-reaction. The ultra-thin petal ZnO flower-like nanostructures can take the role of the effective backbones for succeeding synthesis of electrochemical active materials. The optimized electrodes exhibited an outstanding pseudocapacitive performance, including an excellent durability, wide working potential window (0.55 V in galvanostatic charge-discharge measurement) and a high specific capacitance of 2396.4 F g−1. Additionally, we have constructed an asymmetric supercapacitor device and it delivers a prominent energy density of 62.57 Wh kg−1 at a power density of 711.28 W kg−1 with a cell voltage of 1.5 V and an excellent durability. Thereby, the NF@ZnO@Co(OH)2 is one promising supercapacitors electrode material for practical application.

Graphene oxide coated flower-shaped ZnO nanorods: Optoelectronic properties

Abstract In this paper, the influence of graphene oxide coating on optical and photoluminescence properties of zinc oxide nanorods (ZnO NRs) has been investigated. ZnO NRs were prepared using a hydrothermal route (from zinc nitrate hexahydrate and hexamethylenetetramine), graphene oxide (GO) was fabricated by Hummer’s method, while for synthesis of ZnO nanorods:graphene oxide nanocomposite (ZnO NRs:GO) on Si (100) substrate, a facile technique (drop coating) was proposed. The structural, morphological, optical and luminescence properties of the films were investigated using X-ray diffraction (XRD) technique, scanning electron microscopy (SEM), together with Fourier transform infrared (FT-IR), Raman, ultraviolet–visible–near-infrared (UV/VIS/NIR) and photoluminescence (PL) spectroscopies. As revealed by XRD analysis, composites display a hexagonal wurtzite type structure with a (101) preferred grain orientation. The average crystallite sizes decrease from 45 to 40 nm after GO coating. The SEM study confirms successful coating of GO layers on flower-like ZnO nanostructures. The FTIR and Raman analyses validated the hybridization of nanocomposite and the strong interaction between ZnO NRs and GO. The band gap of the ZnO NRs:GO nanocomposite is lower (2.95eV) compared to that of ZnO NRs (3.11 eV), as determined from the analysis of UV absorbance spectra. The ZnO NRs:GO nanocomposite exhibits a broad PL band, from ∼450 nm to ∼750 nm, with a nearly white-light integrated emission and a chromaticity coordinate of (0.25, 0.34). Gaussian deconvoluted broad PL band exhibits three distinct sub-bands, associated with radiative recombinations in ZnO and GO.

Synthesis of superhydrophobic flower-like ZnO on nickel foam

Superhydrophobic ZnO flower-like nanostructures with good thermal stability were synthesized on the nickel foam by a combination of hydrothermal and single dip-coating methods.

Ag and Cu2O modified 3D flower-like ZnO nanocomposites and evaluated by photocatalysis oxidation activity regulation

In this study, Ag and Cu2O nanoparticles modified flower-like ZnO nanostructures have been successfully synthesized by stepwise method, and the photocatalytic properties were investigated in detail. High-resolution transmission electron microscopy, X-ray diffractions analysis, X-ray photoelectron spectroscopy and scanning electron microscopy were used to analyze the samples. Meanwhile, the derived nanoparticles’ structured and morphologic characters were analyzed by Brunauer–Emmett–Teller. The results have shown that the 3D flower-like ZnO microspheres were composed of 2D ZnO nanosheets decorated Ag and Cu2O and exhibiting flower-like Ag@Cu2O/ZnO architectures. We studied the optical absorption (UV–vis) as well as emission (PL) characters of the specimen and the outcomes suggested more superior photocatalytic characteristics for cuprous oxide and silver co-doped zinc oxide sample compared to other samples. Electron Paramagnetic Resonance test results show that there are mainly ⋅O2−, h+ and OH• free radicals in the process of CR degradation. A Radical-trapping test indicated that of ⋅O2− and h+ was more effective than OH• in the degradation of CR.