Hexagonal Wurtzite Structure Of ZnO Research Articles

Enhanced detection of low concentration volatile organic compounds using advanced doped zinc oxide sensors.

Pure zinc oxide nanoparticles, as well as those doped with 3% calcium, aluminum, and gallium, were synthesized using a sol-gel method and then deposited onto an alumina substrate for sensing tests. The resulting nanoparticles were characterized using a variety of techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), UV-VIS-NIR absorption spectroscopy, and photoluminescence (PL) measurements, to examine their structural, morphological, and optical properties. The prepared nanoparticles were found to have the hexagonal wurtzite structure of ZnO with a P63mC space group. The UV-Vis-IR spectra showed that the samples are highly absorbent in the UV range, while the PL spectra confirmed the presence of many defects in the ZnO structure, such as oxygen vacancies and zinc interstitials. The doped samples exhibited more defects than the pure sample. SEM images of the deposited film surface showed agglomerates with a spherical shape and confirmed the nanometer scale size of our prepared samples, as corroborated by the TEM images. The EDX spectra indicated the high purity of the ZnO deposited films, with a high presence of Zn and O and the presence of the doped elements (Ca, Al, and Ga) in each doped sample. Sensing tests were performed on ZnO, Ca3%-doped ZnO (C3ZO), Al3%-doped ZnO (A3ZO), and Ga3%-doped ZnO (G3ZO) sensors in the presence of volatile organic compounds (VOCs) gases such as ethanol, formaldehyde, methanol, and acetone at low concentrations. The sensors exhibited high responses to low ppm level concentrations of the VOCs gases. At a low operational temperature of 250 °C, the C3ZO sensor had the highest response to 5 ppm of ethanol, methanol, and formaldehyde gases compared to the pure and other doped sensors. Additionally, the A3ZO sensor exhibited the highest response to acetone gas. In conclusion, our findings suggest that the doping of zinc oxide can enhance the low concentration detection of VOCs gases, with the C3ZO and A3ZO sensors showing the highest response to specific gases.

Development of Eco-Friendly TiO2 Doped ZnO Nanorods Based Dual Functional Sensor for the Sewage System Monitoring

Pertaining to the drainage of urban runoff and the expulsion of sewage, sewer systems are a vital component of urban engineering. Owing to this, a dual functional sensor to detect the toxic gases and pipeline leakages was developed with TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> doped (1, 3 and 5Wt. %) ZnO nanorods using a wet chemical approach. The morphological and structural analysis depicts the formation of nanorods morphology and characteristic ZnO hexagonal wurtzite structure (dominant (002) peak plane) despite doping. A decrease in bandgap (optical analysis −3.03 eV) and internal resistance (Nyquist plot–74 Ω) was observed when doped with 5Wt.% of TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . A distinguishing p-n junction curve was observed in all the doped samples during the photoconductivity (J-V) study. A systematic experimental exploratory of the developed sensors at room temperature unfolds the improved dual functional property of the developed sensors when exposed to target gases (10 ppm) (CH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> –0.60 and CO–0.64) and acceleration (2.45 V at 1 g).

Synthesis and antibacterial activity of nanoenhanced conjugate of Ag-doped ZnO nanorods with graphene oxide

In this paper, we report a successful synthesis of ZnO nanorods using the microwave-assisted technique, solid-state reaction method was utilized for the preparation of Zn1-xAgxO (x = 0.05, 0.1), Hummer’s modified method for graphene oxide (GO) along with the sonication method to prepare GO-based Ag-doped ZnO (Zn1-xAgxO/GO: x = 0.05, 0.1) nanocomposites. These nanorods and nanocomposites were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy for structural properties, scanning electron microscopy (SEM) along with energy dispersive X-ray (EDX) spectroscopy for morphological analysis, and UV–Vis spectroscopy for optical properties. XRD, FTIR, and Raman measurements substantiated that each sample is well crystallized in the single-phase polycrystalline wurtzite hexagonal structure of ZnO. The average crystallite size is found to be in decreasing order ranges 40 nm to 29 nm, respectively, along with a significant reduction in the optical bandgap. The SEM images showed a clear evidence of nanorods of ZnO, while the EDX spectra verified the presence of Zn, Ag, O, and C elements in the synthesized samples with their nominal percentage. Furthermore, the prepared nanocomposites effectively inhibited the growth ofStaphylococcus aureus and Escherichia coli. In comparison to pure ZnO nanorods, GO-based Ag-doped ZnO nanorods showed improved antibacterial activity against both S. aureus and E. coli.

Hydrothermal growth of ZnO nanostructures with dopants Co2+, Ni2+ and Cu2+ - Structural and luminous characteristics

Transition metal doped ZnO: (Co/Ni/Cu) nanostructures grown using hydrothermal technique at an optimized growth temperature of 200 °C and a growth time of 3 hours exhibit violet photoluminescence emission. The scanning electron micrographs recorded from the as synthesized samples (ZnO:Co, ZnO:Ni and ZnO:Cu) display nanorods, nanosheet and nanoflower morphology depending upon the dopant/doping percentage. The X-ray diffraction and Raman analysis confirm that hexagonal wurtzite structure of ZnO is retained even after nominal doping of Co, Ni and Cu ions. Optical properties of hydrothermally grown ZnO crystals were analysed with respect to doping concentration (3, 4 and 5 wt%) of Co, Ni and Cu. The optical band gap of ZnO:Co decreases with increasing doping concentration, where as in the case of ZnO:Ni and ZnO:Cu, the band gap increases with increasing the doping concetration. Intense violet deep level emission was observed from ZnO:Co, ZnO:Ni and ZnO:Cu samples at room temperature and the intensity of violet luminescence decreased with increasing the doping concentration of Co2+, Ni2+ and Cu2+ ions into ZnO.

Bio-fabrication of Ni doped ZnO nanoparticles using Annona Muricata leaf extract and investigations of their antimicrobial, antioxidant and photocatalytic activities

The present work aims to investigate the structural, optical, antimicrobial, antioxidant and photocatalytic activities of Zn1−xNixO (x = 0, 0.03, 0.05 & 0.07) nanoparticles prepared by the green method using Annona Muricata leaf extract. The synthesised nanoparticles were analysed by XRD, FTIR, XPS, HRTEM- SAED, SEM- EDX and UV-Visible spectroscopy. The XRD pattern confirms Ni has been successfully incorporated into the hexagonal wurtzite structure of ZnO. XPS results demonstrate the binding energies of ZnO and Ni. The presence of Zn-O vibrational modes was identified by FTIR spectra. The morphology of prepared samples was investigated through SEM and TEM analysis. The presence of Zn, O and Ni elements in EDX spectra indicates the purity of the sample. The optical bandgap energy of ZnO nanoparticles decreases with an increase in Ni concentration. Antimicrobial activity of nanoparticles were carried out against s.aureus, B.subtilis and P.aeruginosa bacterial strains as well as the fungal strain of A.niger and C.albicans. ZnO nanoparticles have significant antioxidant activity against DPPH free radicals. Under solar irradiation, Zn0.93Ni0.07O nanoparticles exhibit excellent photocatalytic degradation against malachite green (98.4 %) and methylene blue (94.9 %) dye solutions. Finally, these findings suggest an effective utilization of phytochemicals present in the A.muricata leaf extract as a suitable source for biosynthesis of pure and Ni-doped ZnO nanoparticles utilised for biomedical and industrial waste water treatment applications.

Enhancement in the Transport and Optoelectrical Properties of Spray Coated ZnO Thin Films by Nd Dopant

This research work focuses on the influence of Neodymium (Nd) doping (0–10 at.%) on the structural, optical, electrical, and photo-response properties of Zinc Oxide thin films deposited on glass substrates by cost-effective spray pyrolysis technique. For all the deposited films, the X-ray diffraction peaks matched the hexagonal wurtzite structure of ZnO with the maximum intensity along the (1 0 1) plane. Using XRD data, the crystallite size, dislocation density, and micro-strain of the films were estimated. Compared to other films, Zn0.96Nd0.04O film exhibited higher crystallinity ~ 18 nm. At higher doping concentrations, a fibrous-granular mixed structure was observed. Above 80 percentage of transparency in the visible region and bandgap of 3.42 eV was observed for the Zn0.96Nd0.04O film. The decrease in Urbach energy with increase in the doping concentration indicated the improvement in crystallinity. The peaks related to band edge emission, zinc, and oxygen-related defects were observed in the photoluminescence analysis also increased band edge emission and lesser defects were observed in the Zn0.96Nd0.04O film. The highest charge carrier concentration ~ 1.7 × 1017 cm−3 and mobility ~ 62.8 cm2/Vs were noticed in of Zn0.96Nd0.04O film. When exposed to UV light, Zn0.96Nd0.04O film exhibited the maximum photocurrent ~ 10−4 A. Hence the Zn0.96Nd0.04O film can be used as a UV photodetector.Graphical

Studies on photocatalytic performance and supercapacitor applications of undoped and Cu-doped ZnO nanoparticles

The structural, morphology and optical properties were characterised using XRD, FTIR, SEM, TEM, and UV-DRS for the undoped and Cu-doped ZnO NPs with varying Cu doping molar concentrations from 0 wt% to 6 wt% through the co-precipitation method. The presence of a ZnO hexagonal wurtzite structure for all samples was confirmed by the structural study of the Cu-doped ZnO NPs, indicating the incorporation of Cu2+ ions into the ZnO lattice by substitution and average crystallite sizes of 25–22 nm. The surface morphology analysis of undoped and Cu-doped ZnO NPs indicated the growth of spherical nanocrystallites with fine particles. Optical studies of Cu-doped ZnO nanostructured particles revealed that increasing the Cu doping agent from 0 wt% to 6 wt% resulted in a blue shift of the absorption band with increasing band gap energy from 3.27 eV to 3.44 eV. The degradation efficiency of MB is 89.2% for Cu-doped ZnO photocatalyst, which performs much better than undoped ZnO under natural sunlight irradiation. The electrochemical analysis determined the specific capacitance of 10 to 100 mV/s scan rate for all the samples. Amongst the various concentrations, 6 wt% Cu-doped ZnO had the most excellent specific capacitance of 539.87 F/g at 10 mV/s. Compared with undoped ZnO NPs, Cu-doped into the ZnO matrix enhanced photocatalytic activities and electrochemical performance for wastewater treatment and supercapacitor applications.

Influence of K/Mg co-doping in tuning room temperature d0 ferromagnetism, optical and transport properties of ZnO compounds for spintronics applications

Researchers have been making persistent efforts in recent years to find novel and suitable oxide materials with room temperature d0 ferromagnetic characteristics to be utilized in spintronics devices. The fundamental goal of this work is to investigate the effect of K/Mg co-doping on the structural, magnetic, optical, and transport (dielectric and Hall Effect) properties of Zn0.94−yK0.06MgyO compounds produced via solid-state process (y = 0, 0.02, 0.04, 0.06, 0.08). The X-ray diffraction pattern examination of these compounds revealed their hexagonal wurtzite structure. The Raman spectrum also displays the hexagonal wurtzite structure of ZnO without any lattice disorder. The elemental colour mapping demonstrates that all of the elements are dispersed uniformly throughout the compound. The concentration of K/Mg co-doping was increased, and this resulted in an improvement in the dielectric value and ac conductivity. Moreover, low dielectric loss in these compounds is observed and thus projecting it as a potential material to be utilized in high-frequency optoelectronic devices. The analyses of Nyquist plots show that higher Mg co-doping results in an increase of non-Debye kind relaxation and it led to a decrease in the grains and grain boundaries resistance. According to the analysis of dielectric data using the Maxwell-Wagner model, hopping of charge carriers are likely to be responsible for the electrical transport. As revealed from optical property measurement, the band gap was found to be slightly altered and the transmittance value increased from 82% for Zn0.94K0.06O to 86% for K/Mg co-doped ZnO compounds. The Hall Effect investigation clearly indicated p-type conductivity and enhanced carrier density concentration. Furthermore, it has been discovered that these substances exhibit ferromagnetism at room temperature.

Photocatalytic Activity and Mechanism of Cu2+ Doped ZnO Nanomaterials

The photocatalytic activity and mechanism of photocatalysts made of ZnO nanoparticles before and after doping with different Cu2+ concentrations were studied by electron paramagnetic resonance and X-ray diffraction. The nanoparticles were prepared using sol–gel method. UV-vis spectrometers characterized the photocatalytic degradation effect of the composite samples on methyl orange solution. The results of X-ray diffraction showed that the hexagonal wurtzite structure of ZnO changed little by Cu2+ doping. With the increase in doping concentration, the CuO and Cu2O diffraction peaks were detected successively in the crystal. The results of the electron paramagnetic resonance test for all samples indicated three kinds of unpaired electrons with g factors of 2.07, 1.997, and 1.954. Further analysis confirmed them to be Cu2+, V+O, and Zn–H complexes. Photocatalytic degradation results of methyl orange showed that proper doping (c(Cu2+) = 2%) could improve the photocatalytic activity of ZnO. The main reason for the increase was that the substitution of Cu2+ for Zn2+ in the crystal lattice produced Zni, and the Zn atom could act as the donor to release electrons, so that the number of electrons in the material increased, which indirectly increased the superoxide radical content in the solution and improves the photocatalytic activity of ZnO.

Electronic, optical and magnetic properties of Cu-doped ZnO, a possible system for eco-friendly and energy-efficient spintronic applications.

Polycrystalline Zn1-xCuxO (x = 0.0, 0.02, and 0.05) samples have been prepared using the solid-state reaction procedure. The X-ray diffraction (XRD) patterns of the samples confirm that Cu ions are successfully included in the ZnO hexagonal wurtzite structure. Rietveld analysis of the XRD patterns confirms the phase purity of the synthesized samples and a slight variation in their lattice parameter upon Cu doping. The morphology study by scanning electron microscopy (SEM) depicts transfiguration with Cu doping. The existence of oxygen vacancies (Vo) in the Cu-doped samples is indicated by X-ray photoelectron spectroscopy (XPS). The magnetization measurements reveal the diamagnetic nature of pure ZnO while the Cu-doped samples depict a room-temperature ferromagnetic (RTFM) behavior. The 2% Cu-doped sample shows higher values of both the saturation magnetization and the Vo as compared to the 5% Cu-doped sample. The observed magnetization seems to show a direct relationship with the Vo. The photoluminescence (PL) and ultraviolet (UV) spectroscopic measurements were performed for their optical analysis. The presence of Vo in the Cu-doped samples is revealed by the PL findings also that is in agreement with the XPS results. The UV analysis shows that Cu doping in the ZnO influences the band gap. The observed RTFM induced by Cu doping in ZnO renders it a potential system for spintronic devices useful for energy-efficient data storage devices and energy harvesting eco-friendly applications.

Nanocomposites based on doped ZnO nanoparticles for antibacterial applications

Drug-resistant bacteria have become a worldwide health issue, and metal oxide nanoparticles could represent a viable alternative to pharmaceuticals for the treatment and prevention of bacterial infections. In this work, cerium (Ce), neodymium (Nd), samarium (Sm) and erbium (Er) doped ZnO nanoparticles were developed to fabricate 3D-printed composite scaffolds for bactericidal applications. The nanoparticles were prepared by a combustion-assisted method at low temperatures. The hexagonal wurtzite structure of ZnO was confirmed by X-ray diffraction (XRD), and the average crystallite size was ~10 nm. The bioactivity of these nanoparticles was evaluated by culturing them with Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The resulting bacterial kinetic growth curves showed superior antimicrobial activity against S. aureus, killing almost 92% of the bacteria, and intermediate activity against E. coli. The antibacterial activity of the scaffolds was studied to assess their potential for biomedical applications. The bacterial kinetic growth results were utilized as data in an artificial neural network (ANN), which resulted in a model capable of forecasting bacterial growth with high precision (90%).

Zn0.97-xCu0.03VxO (x = 0, 0.02, 0.04) hexagonal tube and microrods structures: Optical, refractive index, electrical and solar photocatalytic properties

The optical, refractive index, electrical, dielectric and solar photocatalytic properties of pure and Zn0.97-xCu0.03VxO (x = 0, 0.02, 0.04) compositions synthesized by coprecipitation method have been studied. Pure single phase of hexagonal wurtzite structure of ZnO was confirmed by XRD and Rietveld refinement analysis. The SEM obviously illustrated that Cu doping and Cu/V codoping have great impacts on morphology of ZnO particles. Remarkably, incorporation of Cu ions converts the spherical shape of the pure ZnO particles to open hexagonal tube and microrods structures while Cu/V ions lead to formation of mixed particles possess microrods and very fine spherical shapes. Optically, lowering in the optical band gap energy of ZnO with formation of long tails extend to visible light wavelengths (460 nm) were detected due to insertion of Cu and Cu/V ions. Based on Ravindra, Moss, Hervé, Reddy, and Kumar models, hexagonal Zn0.97Cu0.03O exhibits the highest refractive index values of 2.1558, 2.3509, 2.2961, 2.7368 and 2.3355, respectively. At different frequencies, 3 wt% Cu doping enhanced the room temperature electrical conductivity values of ZnO and further improvements were seen due to insertion of V3+/4+ ions plus Cu2+ dopant. Zn0.95Cu0.03V0.02O composition revealed a colossal dielectric constant of 1947 at 50 Hz and at nearly all frequency it possesses the highest values. The low cost solar photocatalytic test showed that both Zn0.97Cu·03O and Zn0.93Cu0.03V0.04O catalysts have high efficiencies of 81% and 82% to degrade the organic Congo red pollutant in 90 min.

Synthesis and Characterization of Ag/ZnO Nanoparticles for Bacteria Disinfection in Water.

In this study, two green synthesis routes were used for the synthesis of Ag/ZnO nanoparticles, using cassava starch as a simple and low-cost effective fuel and Aloe vera as a reducing and stabilizing agent. The Ag/ZnO nanoparticles were characterized and used for bacterial disinfection of lake water contaminated with Escherichia coli (E. coli). Characterization indicated the formation of a face-centered cubic structure of metallic silver nanoparticles with no insertion of Ag into the ZnO hexagonal wurtzite structure. Physicochemical and bacteriological analyses described in “Standard Methods for the Examination of Water and Wastewater” were used to evaluate the efficiency of the treatment. In comparison to pure ZnO, the synthesized Ag/ZnO nanoparticles showed high efficiencies against Escherichia coli (E. coli) and general coliforms present in the lake water. These pathogens were absent after treatment using Ag/ZnO nanoparticles. The results indicate that Ag/ZnO nanoparticles synthesized via green chemistry are a promising candidate for the treatment of wastewaters contaminated by bacteria, due to their facile preparation, low-cost synthesis, and disinfection efficiency.

The Effect of Silver Oxide on the Structural and Optical Properties of ZnO: AgO Thin Films

Compounds from ZnO doped with AgO in different ratio (0,3,5,7, and 9)wt.% were prepared.Thin films from the prepared compounds were deposited on a glass substrate using the pulsed laser deposition method. The XRD pattern confirmed the presence of a single-phase hexagonal wurtzite ZnO structure, without the presence of a secondary phase. AFM measurements showed an increase in both average grain size and average surface roughness with increasing concentration content of (AgO).The crystallite size of ZnO of the main peak corresponding to the preferred plane of crystal growth named (100) increases from 17.8 to 22.5nm by increasing of AgO doping ratio from 0 to 9%. The absorbance and transmittance in the wavelength range (350-1100 nm) were used to determine the optical properties. The results showed that the optical energy gap for direct allowed transition (r =0.5 )are (3.21, 3.2,3.15, 3.15, 2.95 ) Ev, respectively. The optical constants were also measured as a function of wavelength. This optical measurements showed the prepared thin film have many applications for solar cell fabrication and sensing devices.

Studies of visible-light-driven Sm-doped ZnO nanoparticles synthesized by combustion method

ZnO nanoparticles with different Sm doping contents were prepared by tartaric acid solution combustion method and followed by calcination at 600 oC for 2 h. The XRD patterns of ZnO and Sm-doped ZnO samples were indexed to the pure phase of hexagonal wurtzite ZnO structure. TEM images of ZnO and Sm-doped ZnO samples show that the samples contained nanoparticles with different particle sizes. Their particle sizes were decreased with increasing in the weight contents of Sm dopant. Their photocatalytic properties were also investigated through the photodegradation of methylene blue (MB) under visible light irradiation. The 3% Sm-doped ZnO nanoparticles have the highest photodegradation of MB under visible light irradiation because Sm3+ as an electron accepter played the role in inhibiting the recombination of charge carrier pa

Enhanced dielectric and optical performance of (Cu, Ag) co-doped ZnO nanostructures for electronic applications

ABSTRACT Pure and Cu/Ag co-doped ZnO nanoparticles were synthesised by the co-precipitation method. The phase and structural analysis of ZnO nanoparticles were examined by using XRD and Williamson-Hall plots. XRD spectra revealed that prepared samples exhibit hexagonal wurtzite structure of ZnO. The change in lattice parameters, bond length, dislocation density and strain indicates that Cu and Ag were successfully incorporated. UV vis studies indicated the red shift in the absorption band attributed to defects induced after dopant additions. The dielectric measurements showed that the dielectric constant was found to increase and the dielectric loss decreases with increase in dopant percentage. Additions of Cu and Ag in ZnO lattice may lead to supplement grain boundary defects which can increase polarisation. The relatively higher values of ac conductivity were also found due to modulation of charge carrier density after dopant additions which suggest that the diffusion controlled charge carrier hopping mechanism is involved.

Structural and Optical Properties of ZnO-TiO&lt;sub&gt;2 &lt;/sub&gt;Nanocomposite Synthesized with Various Molar Ratios by Hydrothermal Technique

Zinc oxide-titanium dioxide (ZnO-TiO2) have been successfully synthesized by hydrothermal method. ZnO-TiO2 nanocomposite were prepared at different molar ratio 100:0, 100:0, 30:70, 50:50 and 70:30. The objective of this research is to determine the effect of molar ratios on the structural and optical properties of ZnO-TiO2 nanocomposite. The samples were analyzed using X-ray diffraction (XRD) analysis, Field-emission scanning electron microscopy (FESEM) and UV-Vis spectroscopy. Based on the XRD results, it is revealed that ZnO-TiO2 nanocomposite consists of hexagonal wurtzite structure of ZnO and mixed of anatase/ rutile phase of TiO2. FESEM images showed ZnO in rod-like structure while TiO2 is formed in nanoparticle. ZnO-TiO2 composite is formed combination of rod-like and nanoparticles. UV-Vis spectra showed that all samples exhibited good absorption towards UV region. The calculated energy band gaps of ZnO-TiO2 composite are 2.92 eV which is slightly smaller compared to bulk ZnO and TiO2. The tuning energy band gaps of ZnO-TiO2 composite samples is a good indicator for use in catalytic activities.

Erbium-doped ZnO nanoparticles for anode materials: A comparative study using anthocyanin and curcumin dyes in DSSC

Nanomaterials doped with rare earth ions have attracted increasing interest in the renewable energy harvesting field. Erbium-doped ZnO nanoparticles were prepared by the solution polymerization method. The hexagonal wurtzite structure of ZnO was preserved, according to X-ray diffraction (XRD) studies, and the average crystallite size is less than 20 nm. The UV–Vis spectroscopy revealed that the optical band gap was 3.1 eV, with peaks associated with erbium-specific electronic transitions appearing when the doping concentration was raised (Er). Anthocyanin and curcumin dyes were employed to build dye-sensitized solar cells devices (DSSCs) employing nanoparticles as photoanodes. When compared to undoped ZnO, Er-doped ZnO at 1.25 at. percent improves power conversion efficiency (PCE) by 200% for anthocyanin dye and 10% for curcumin dye.

Green synthesis of RGO-ZnO mediated Ocimum basilicum leaves extract nanocomposite for antioxidant, antibacterial, antidiabetic and photocatalytic activity

Green chemistry of nanomaterials from synthesis to diverse biomedical applications is a discussion of town in the current scientific scenario. In this work, Ocimum basilicum leaves extract was utilized as the reducing agent in the synthesis of ZnO nanoparticles. Green synthesized ZnO NPs mediated via Ocimum basilicum extract were decorated on the reduced graphene oxide (RGO) sheet by the simple one-step method. The prepared green synthesized RGO-ZnO nanocomposites (NCs) were characterized via the X-ray diffractometer. The average crystallite size of ZnO was 25 nm which confirmed the wurtzite hexagonal structure of ZnO. The scanning Electron Microscopy technique confirmed the spherical morphology of particle size of 31 nm. Further, Fourier Transform Infrared Spectroscopy confirms the Zn-O bond stretching in the RGO-ZnO NCs. Antioxidant activity of the green synthesized Ocimum basilicum ZnO NPs and RGO-ZnO NCs were performed by DPPH scavenging activities and found the dose-dependent. RGO-ZnO effectively inhibited the α-amylase and α-glucosidase for in vitro antidiabetic activities. Moreover, RGO-ZnO NCs showed the antibacterial potential with increasing concentration against the gram-positive (Cocci) and gram-negative (E. coli) bacterial strains. In Photocatalytic activity, the ZnO NPs and RGO-ZnO NCs were utilized as the catalyst and degraded the Rh-B dye 91.4% and 96.7% under UV–visible light. Overall, RGO-ZnO NCs showed better results in antibacterial, antidiabetic activity as well as photocatalytic activity against the pure ZnO NPs. Hence, RGO-ZnO nanocomposites have demonstrated the opportunity to be an entrancing material for photocatalysis and biological studies.

Defect emission photoluminescence peak tuning by encapsulation of Au-NPs on ZnO mesoporous nanosponges

We synthesized Au nanoparticles (Au-NPs) encapsulated zinc oxide (ZnO:Au) nanosponges by the fraternization of ZnO nanoflowers with HCl (0–30 mM) concentrated colloidal Au-NPs at room temperature. The crystallite size (D) of mesoporous ZnO:Au decreased from 44 nm to 22 nm and the strain (τ) increased from 2.5 × 10−3 to 4.7 × 10−3 as the HCl concentration of colloidal Au-NPs increased from 0 mM to 30 mM. For elemental composition of ZnO:Au nanosponges, the STM-mapping confirmed the Au-NPs encapsulation on nanostructured ZnO. The bandgap, Eg, and the Urbach energy, Eu, of ZnO:Au decreased from 3.26 to 2.96 eV, and from 0.335 to 0.318 eV, as the colloidal Au-NPs increased from 0 mM to 30 mM, respectively. The structural and microstructure analysis showed the sponge like morphology along with wurtzite hexagonal structure of ZnO, which tuned the PL emission for the sensor selectivity. The visible emission of ZnO:Au nanosponges was greatly tuned from 600 nm to 500 nm with respect to the HCl diluted colloidal Au-NPs. The excellent photoluminescence (PL) performance of nanostructured ZnO:Au was attributed to the surface-plasmon-mediated sequential transfer of defect energy from ZnO to Au and electron transfer from excited Au to ZnO.