Hexagonal Nanorods Research Articles

An effect of hydrophobicity of cosurfactant on the growth of cerium tetrafluoride hexagonal nanorods in water-in-oil microemulsion template

This study involves the effect of hydrophobicity of cosurfactants on the formation of cerium tetrafluoride nanoparticles inside the core of water-in-oil microemulsion. To produce the microemulsions, two distinct chain length cosurfactants, 1-butanol (4 carbon atoms) and 1-hexanol (6 carbon atoms) are employed. Dynamic light scattering (DLS) study reveals that, for both types of microemulsion, the synthesis of nanostructures typically occurs in three stages: nucleation phase (around first 15 min), transition phase (30–60 min) and growth phase (60–120 min). Microstructural analysis of Field Emission Scanning Electron Microscopy (FESEM) supports the evolution of hexagonal nanorods. In comparison to reverse micellar media based on 1-hexanol, 1-butanol based reverse micellar media participates in faster reaction. Longer hydrophobic chain length of 1-hexanol enhances the surface film rigidity and produces a well-defined phase boundary, which reduces intermicellar exchange and leads to the evolution of smaller hexagonal nanorods. Therefore, this study may assist the researcher to better understand how cosurfactants influence the growth of nanostructures of lanthanide series metal nanoparticles, using a microemulsion template.

Waste rice noodle-based CQDs/ZnO composite nanorod array on steel wire mesh: Preparation and photocatalytic capability

In order to develop cost-effective photocatalytic devices, a nanorod array-structured carbon quantum dot/zinc oxide (CQDs/ZnO) composite was synthesized on a steel wire mesh substrate using waste rice noodle (WRN) as the raw material. The incorporation of CQDs derived from WRN played a crucial role in controlling the morphology of the ZnO-based array. By optimizing the loading of CQDs, the CQDs/ZnO composite achieved a regular hexagonal prism nanorod array distribution and exhibited highly efficient photocatalytic degradation of various organic pollutants. For instance, in the case of methylene blue, the CQDs/ZnO composite demonstrated a remarkable degradation rate of 99.4% within 90 min, with a high degradation rate constant of 0.033 min−1. Moreover, the composite material could be recycled and reused for five photocatalytic cycles without a significant decrease in its degradation performance, surpassing the performance of the pure ZnO array. Furthermore, the resulting CQDs/ZnO composite array exhibited effective photocatalytic degradation for other organic dyes such as malachite green, methyl violet, basic fuchsin, and rhodamine B. Additionally, this composite material was successfully applied to real water purification, achieving a high mineralization efficiency of 48% and a low leaching rate of Zn of 1.2% in a river water sample after a 90-minute photocatalytic process. The introduction of CQDs derived from WRN into the ZnO array led to efficient electron-hole pair separation, enabling more photogenerated electrons to reduce O2 and more photogenerated holes to oxidize H2O. This resulted in enhanced radical generation and improved photocatalytic degradation of organic pollutants, showcasing the superior performance of the CQDs/ZnO composite array.

Temperature impact on the morphological evolution of nitrogen-doped carbon quantum dot-decorated zinc oxide and its influence on highly efficient visible-light photocatalyst

Nitrogen-doped carbon quantum dot-decorated zinc oxide (ZnO/NCQD) was synthesized using a hydrothermal process under various thermal conditions. XRD (X-Ray Diffractometer) and field emission-scanning electron microscopy (FE-SEM) confirmed the crystal structure of wurtzite, and there was a morphological evolution from a hexagonal nanorod to a nanoflower. Simultaneously, the optical properties and photocatalytic activity were investigated using UV–visible diffuse reflectance, photoluminescence, and UV–vis spectrophotometers. The presence of NCQD on the ZnO surface lowers the bandgap energy and shifts the absorbance toward visible light. As a result, it enhanced the photocatalytic activity and efficiency of ZnO/NCQD, achieving approximately 80% methylene blue (MB) degradation in 15 min under visible light. It was concluded that the hydrothermal temperature played a role in the particle growth of the ZnO/NCQD and affected the optical and photocatalytic properties. Therefore, the fabricated ZnO/NCQD has excellent potential for photocatalytic dye degradation.

Ultrahigh-power all binder-free hybrid supercapacitors based on single-crystal hexagonal nanorods of molecular sieve VSB-5 hierarchical electrodes

BackgroundMolecular sieve Versailles Santa Barbara-5 (VSB-5) is a highly porous nanomaterial for electrochemical supercapacitor. MethodsA facile hydrothermal method is used to directly synthesize VSB-5 nanorods onto the Nickel Foam (NF). Significant findingsIn this work, one-dimensional single-crystal hydrogen nickel phosphate hydroxide hydrate (Ni20[(OH)12(H2O)6][(HPO4)8(PO4)4]·12H2O, also denotes as VSB-5, hexagonal nanorods arrays are successfully synthesized on NF via a hydrothermal method, and applied them as positive electrodes for hybrid supercapacitor (HSC). The resultant open framework of VSB-5 with unique nanochannels provides the synchronous advantages of a large surface area with numerous active sites for enhancing faradic redox reactions and abundant pathways for promoting electrolyte ions diffusion, thus leading to excellent energy storage behavior. Furthermore, the HSC is fabricated by paring the direct growth of carbon nanotubes (CNTs) on NF as the electrical-double-layer-capacitor negative electrode. Both the VSB-5/NF and CNTs/NF electrodes are binder-free hierarchical structures, owning the lowest interfacial resistivities between active materials and current collects, avoiding the aggregation issues to allow the facile diffusion of electrolyte for maximally utilizing the surface area. The resultant all binder-free VSB-5/NF//CNTs/NF HSC shows remarkable electrochemical performance, which delivers a maximum energy density of 46.9 W h kg−1 at a power density of 1225 W kg−1 with excellent capacity retention of 98.18% after 10,000 cycles.

Designing a perfect surface plasmon resonance absorber based on graphene and hexagonal boron nitride photonic crystal nanorods

In this work, absorbers in the terahertz region based on one-dimensional photonic crystal nanorods coated with phosphorene, phosphorene-graphene, and phosphorene–hexagonal boron nitride layers were designed. On addition of a graphene layer to the structure, strong localized surface plasmon resonance was observed in two different plasmonic modes via two significant peaks at wavelengths of 10.09 μm and 12.47 μm. The absorption of the structure was affected by the presence of an antireflection layer, and the two modes showed an absorption rate of 99% at wavelengths of 9.72 μm and 9.86 μm, increasing the absorption band to 0.54 μm full width at half maximum. By our changing the dielectric environment with a higher refractive index, better localization and greater absorption occurred. Furthermore, a perfect absorber with two absorption peaks at wavelengths of 11.39 μm and 14.02 μm with 99% and 97% absorption and full width at half maximum of 0.35 μm and 1.1 μm, respectively, was created. Finally, a perfect absorber with an absorption bandwidth of 2.1 μm was obtained in the structure in which hexagonal boron nitride had been placed as a spacer between the monolayers of phosphorene.

Surface-dependent CO oxidation over Au/ZnO nanopyramids and nanorods

The catalytic activity of metals is very sensitive to the surface orientation of supporting oxides but rather little is known about ZnO in this regard. Nanostructured support morphologies present an attractive research strategy there because they allow probing the catalytic impact of well-defined surfaces at ambient pressure. The predominant {101̅0} side planes of hexagonal ZnO nanorods (NR) are terminated with the same number of O and Zn atoms while both the (0001) basal and {101̅1̅} side planes of hexagonal ZnO nanopyramids (NPy) are Zn-terminated. STEM analyses reveal two Au//ZnO interfacial configurations for each system after deposition of ∼3 nm Au nanoparticles. CO oxidation proceeds 15 times faster over the Au/ZnO NR than the Au/ZnO NPy catalyst at room temperature. The difference in catalytic activity can be traced to facilitated CO activation at the interfacial sites of Au/ZnO NR while it is retarded due to co-adsorption of CO with CO32- at undercoordinated Zn2+ ions of the interfacial perimeter of Au/ZnO NPy according to CO DRIFTS analyses. These results demonstrate that the catalytic behavior of metal/ZnO systems are very sensitive to ZnO surface terminations and the associated metal//ZnO interface configurations.

Preparation of ultrafast ammonia sensor based on cross-linked ZnO nanorods coated with poly(3-hexylthiophene)

A gas sensing device was fabricated using poly(3-hexylthiophene) (P3HT)-coated ZnO nanorods, and the ammonia (NH3) gas-sensing properties of the heterojunction device were analyzed. Hexagonal ZnO nanorods were prepared using the hydrothermal method on a ZnO seed layer. The ZnO seed layer was deposited using the sputtering method on a Ti–Pt bilayer interdigital electrode. X-ray diffraction and field emission scanning electron microscopy characterized the crystal structure and morphology of the ZnO–P3HT nanorods heterojunction devices. The gas-sensing properties of the P3HT–ZnO nanorods heterojunction sensor were examined and compared with different concentrations of NH3 gas. The response and recovery times were less than 1.5 s with a NH3 gas concentration of 1 ppm. Comparison with sensors of other materials indicated that P3HT was the reason for the short response and recovery times. Plausible mechanisms explaining the enhanced NH3 selectivity of the P3HT–ZnO nanorods heterojunction structure are discussed.

A manganese dioxide nanoparticle-bimetallic metal organic framework composite for selective and sensitive detection of vitamin D3 in human plasma.

For the first time a metal organic framework nanomaterial has been developedcomprising manganese dioxide nanoparticle and iron and zinc metal ions interlinked with each other via terephthalic acid. The framework shape was identified as an elongated hexagonal nanorod (TEM) with varying functional groups (FT-IR) and diffraction patterns (XRD). The framework nanocomposite as such in aqueous acidic electrolyte solution has displayed an excellent conductivity (redox behavior) and surface excess (3.08 × 10-8 cm-2). Under the optimized conditions (0.1 M H2SO4 as electrolyte, 50 mV/s scan rate, +1.26 V (vs Ag/AgCl)), the metal organic framework coated electrode has selectively identified vitamin D3 (VD3) in the presence of various other interfering molecules and displayed excellent limit of detection (1.9 ng mL-1). The developed sensor has been applied to the determination of VD3 in extracted human plasma samples (RSD of 0.3-2.6 % and recovery of 96-102 %), and the obtained VD3 values are similar to HPLC-UV method.

Novel ZnO/BiOI nanorod photoanode with interface p-n heterojunction and excellent photoelectric conversion efficiency for photocathodic protection of stainless steel

Bismuth oxyhalide nanoheterojunctions with high photovoltaic conversion efficiency by constructing internal electric field have received extensive attention for photocathode protection (PCP) applications. In this work, BiOI/ZnO nanorod composites (BiOI/ZnO NRs) were synthesized by spin coating and hydrothermal method. The BiOI nanoparticles were found uniformly anchored on the surface of hexagonal wurtzite ZnO nanorods. Morphology and Mott Schottky plots analysis confirm the structure of the p-n heterojunctions at the interface of BiOI and ZnO. Loading of BiOI on the ZnO surface results in the negative shift of the Fermi level of ZnO. The BiOI/ZnO NRs expanded the absorption region of solar light and constructed an internal electric field in p-n heterojunction, which more efficiently accelerated the migration of electrons, inhibited the carrier’s recombination and improved the photoelectric conversion efficiency of BiOI/ZnO. The Open circuit potential (OCP) of BiOI/ZnO NRs photoanode coupled with the 304 stainless steel negatively shifted to −0.757 mV (vs.SCE), and it could protect stainless steel steadily in 4000 s intermittent illumination, showing the high stability of BiOI/ZnO photoanode. The synergistic effects of p-n heterojunction enable BiOI/ZnO NRs photoanode to exhibit an excellent photocathode protection performance.

The intriguing bifunctional effect of strong metal support interaction (SMSI) and hydrogen spillover effect (HSPE) for effective hydrogen evolution reaction

The mechanistic insights behind the kinetics of Hydrogen evolution reaction are unraveled through the bifunctional effect - Strong Metal Support Interaction (SMSI) and Hydrogen Spillover Effect (HSPE) on the WO3 hexagonal nanorods decorated with gold clusters and supported on the reduced graphene layers. The investigation is extended to scaling the electrocatalyst in a flexible electrode-carbon fiber for robust hydrogen evolution reaction in broad pH spectra. The research found that the proposed electrocatalyst demonstrated a reduced overpotential of 20 mV at a current density of 10 mA cm2 in acidic conditions and the stability of the ternary catalyst was verified through the Pourbaix profile. The Tafel slope was also comparable to that of the noble metal electrocatalyst Pt/C, with values of 35 mV dec–1 in 0.5 M H2SO4. The study demonstrated the potential for large-scale application of the proposed catalyst with stable operation observed for 24 h.

Oxygen defect rich Bi2S3/SnS2/Bi-self doped Bi2W2O9 multijunction photocatalyst for enhanced degradation of methyl parathion and H2 evolution

In this study, a facile in situ co-assembly technique is developed for one pot fabrication of Bi2S3/SnS2/Bi2W2O9 multijunction photocatalyst. Initially, Aurivillius phase Bi2W2O9 with nanoplate morphology is prepared by combustion synthesis route. The hydrothermal co-deposition of SnS2 and Bi2S3 phase led to the formation of the ternary composite photocatalyst. During hydrothermal treatment, substantial microstructural reorganization of the BWO phase occurred resulting in exfoliation of the nanoplates to high aspect ratio nanosheets followed by substitution of Bi5+ ions in the [W2O7]2- bilayer of the BWO structure. The Bi-self doping phenomena also resulted in creation of oxygen vacancy in the BWO lattice. Morphological investigations revealed intimate interfacial contact among hexagonal SnS2 nanoplates, Bi2S3 nanorods and Bi-doped Bi2W2O9 nanosheets. The oxygen vacancy (OV) and Bi self-doping endow improved photoelectrochemical properties and enhanced photocatalytic activity towards methyl parathion photodegradation (kapp = 0.013 min−1) and hydrogen evolution (0.92 mmolg-1h−1). The optimal BS15BWO photocatalyst exhibited nearly 13 and 32 times higher photocatalytic activity for methyl parathion photodegradation and H2 evolution reaction in comparison to the pure components. The robust generation of •OH and •O2− radicals and improved charge channelization through a type-I conjugated dual S-scheme electron migration mechanism accounted for the improved photocatalytic activity of the ternary composite.

Heterostructured CdS Buffer Layer for Sb2Se3 Thin Film Solar Cell

The antimony selenide thin film solar cells technology becomes promising due to its excellent anisotropic charge transport and brilliant light absorption capability. Especially, the device performance heavily relies on the vertically oriented Sb2Se3 grain to promote photoexcited carrier transport. However, crystalline orientation control has been a major issue in Sb2Se3 thin film solar cells. Herein, a new strategy has been developed to tailor the crystal growth of Sb2Se3 ribbons perpendicular to the substrate by using the structural heterostructured CdS buffer layer. The heterostructured CdS buffer layer is formed by a dual layer of CdS nanorods and nanoparticles. The hexagonal CdS nanorods passivated by a thin cubic CdS nanoparticle layer can promote [211] and [221] directional growth of Sb2Se3 ribbons using a close space sublimation approach. The improved buffer/absorber interface, reduced interface defects, and recombination loss contribute to the improved device efficiency of 7.16%. This new structural heterostructured CdS buffer layer can regulate Sb2Se3 nanoribbons crystal growth and pave the way to further improve the low‐dimensional chalcogenide thin film solar cell efficiency.

Effect of yttrium doping on the crystal structure, optical, and photocatalytic properties of hydrothermally synthesized ZnO nanorods

The hydrothermal technique was utilized to fabricate yttrium doped ZnO nanorods (Y-doped ZnO). Various spectroscopic approaches were used to examine the effect of yttrium doping on the crystal structure, shape, energy bandgap, and photocatalytic performance of ZnO nanorods. The fact that Y-doped ZnO nanocatalysts had the same hexagonal wurtzite crystal structure and nanorod shape as like undoped ZnO, signifying that doped yttrium ions have no effect on the structural as well as morphological features of ZnO nanorods. By doping yttrium into the ZnO sites, the bandgap energy of the ZnO nanorods was significantly altered, and the photodegradation activity was improved. The absorption edge of the Y-doped ZnO nanorods was shifted towards the higher wavelengths and blue shift in bandgap was observed. It has been confirmed that yttrium doping increases the light sensitivity of ZnO in the visible region while providing several active charge transporters on the nanorods surface as well. The photocatalytic activity of Y-doped ZnO nanocatalysts was significantly increased by generated charge carriers. For doping concentrations of 1 %, 3 % and 5 %, the photodegradation activity of Y-doped ZnO nanorods is 71 %, 97 %, and 82 %, respectively, whereas the photodegradation efficiency of pure ZnO nanorods is 22 %. The photodegradation efficiency of ZnO:Y3 was found to be 4.4 times higher than the pristine ZnO nanorods. In addition to the photodegradation, the Y-doped ZnO nanorods are anticipated to offer a valued platform to the widespread applications in the field of photocatalysis like electrochemical water splitting, hydrogen production and supercapacitors.

Degradation of methylene blue and rhodamine B by hollow ZnO microspheres formed of radially oriented nanorods

It is crucial to find effective solutions to environmental contamination that are also ecologically friendly. Zinc oxide (ZnO) is well-known as a good photocatalyst. In this work, ZnO microspheres were synthesized using the solvothermal technique. X-ray diffraction (XRD), UV-Vis, and scanning electron microscopy(SEM) were used to evaluate the structural, optical, and morphological features of ZnO microspheres . The hexagonal structure of ZnO was determined using XRD analysis. The crystal size of ZnO was calculated using XRD patterns and was found to be 44.27 nm by the Debye-Scherrer equation, 32.39 nm using the Williamson Hall model, and 9.92 nm by the Modified Scherrer formula. The SEM pictures of the manufactured ZnO revealed that it has a shape in the form of microspheres formed by the conjunction of hexagonal nanorods. The average diameter of these microspheres is 5.16 μm. ZnO has a band gap energy of 3.1 eV. The photocatalytic activities of ZnO microspheres against methylene blue and Rhodamine B dyes were examined. Under sunlight, photocatalytic removal rates for methylene blue after 90 minutes and Rhodamine B after 120 minutes were 98.95% and 98.62%, respectively.

Structure-dependent room-temperature hydrogen sensing of Nb2O5 nanorods prepared by topological transformation process

The development of reliable low-power-consumption hydrogen gas sensors is of great significance for the accurate detection of hydrogen leakage in the hydrogen-related industries. Nb2O5 nanomaterials have exhibited great potential for building highly selective hydrogen sensors owing to its outstanding hydrogen catalytic capability, but still suffer from relatively low hydrogen sensitivity at room temperature. Herein, the orthorhombic and hexagonal Nb2O5 nanorods with different defect states are prepared through a combined topological transformation process. The Nb2O5 nanorods with polycrystalline orthorhombic structures exhibit much higher room-temperature hydrogen response comparing with the single-crystalline hexagonal Nb2O5 nanorods. Moreover, both phases of the Nb2O5 nanorods exhibit certain amounts of oxygen vacancies, as well as the interstitial Nb4+ and related oxygen defects. The elimination of the Nb4+ and related oxygen defects can significantly enhance the surface reactivity of the Nb2O5 nanorods and improve the sensor response of the chemiresistor devices. The sensor based on the defect-modified orthorhombic Nb2O5 nanorods shows sensitive and highly selective room-temperature hydrogen sensing performance with the detection limit of 160 ppm. The structure-dependent hydrogen sensing behavior of the Nb2O5 nanorods can be attributed to the redox reaction between hydrogen and pre-adsorbed oxygens, which can be promoted by the superior gas adsorption and pathway effect of the orthorhombic Nb2O5 lattice.

RGO‐Wrapped Hexagonal WO3 Nanorod as Advanced Electrode Material for Asymmetric Electrochemical Supercapacitors

The multiple oxidation states of redox‐active materials enable them to store high‐energy better than the commonly used carbon‐based electrode materials. Accounting for these advantages, designing asymmetric supercapacitors by coupling redox‐active materials as positive electrodes with carbon‐based negative electrodes becomes a very attractive strategy. Herein, reduced graphene oxide‐wrapped hexagonal WO3 nanorod (rGO‐WO3 NR) by simple hydrothermal synthesis method is synthesized. Because of improved reaction kinetics resulting from the close contact between rGO and WO3 NRs, rGO‐WO3 NR demonstrates superior electrochemical properties than pure WO3. Motivated by the very high areal capacitance (2.5 F cm−3 at the applied current of 30 mA cm−2), an asymmetric SC device by combining rGO‐WO3 NR with activated carbon is assembled. The as‐assembled rGO‐WO3 NR//activated carbon asymmetric supercapacitor device demonstrates outstanding electrochemical performance in an operating voltage window of 1.2 V, admirable cycling stability of ≈95% (even after 14 000 cycles), with an energy density of 24.1 Wh Kg−1 at a power density of 1532.6 W Kg−1. These demonstrate the combination of redox‐active materials with high energy density can importantly boost the energy storage capacity of a supercapacitor.

Synthesis, Characterization, and Properties of Sulfonated CNT‐Doped Poly(aniline‐co‐carbazole)‐PVA Conductive Films

AbstractConductive flexible films are successfully synthesized from polyvinyl alcohol matrix and poly(aniline‐co‐carbazole) charge carrier. To improve the mechanical properties of polyvinyl alcohol and promote charge transition in the conductive copolymer, dual purpose sulfonated multiwall carbon nanotube is added. Conductivity is enhanced via sulfonic acid protonic dopant and mechanical property is increased by its hexagonal nanorods. Nanocomposites are prepared by adding 0.025, 0.050, and 0.075 g of carbon nanotube which is added at 1%, 3%, and 5% loads to the polymer matrix. Films are characterized by infrared, UV–vis, X‐ray diffraction, scanning electron microscopy, and thermogravimetric analysis. Conductivity is measured by the four‐probe technique and mechanical property is assessed through tensile tests and dynamic mechanic thermal analysis. A 5 × 10−6 S cm−1 conductivity and 116 MPa tensile strength are recorded for the conductive film with optimum dopant/nanocomposite loads. The electrochemical property and corrosion resistance are studied by cyclic voltammetry and Tafel curves, respectively. The conductive films show an increase in corrosion potential and a decrease in corrosion current referring to a reliable corrosion protection film. The water uptake and contact angle of the films are measured to be 157% and 80.1° respectively to confirm its required hydrophilic property.

WO3 Nanorods Decorated with Very Small Amount of Pt for Effective Hydrogen Evolution Reaction

The electrochemical hydrogen evolution reaction (HER) is one of the most promising green methods for the efficient production of renewable and sustainable H2, for which platinum possesses the highest catalytic activity. Cost-effective alternatives can be obtained by reducing the Pt amount and still preserving its activity. The Pt nanoparticle decoration of suitable current collectors can be effectively realized by using transition metal oxide (TMO) nanostructures. Among them, WO3 nanorods are the most eligible option, thanks to their high stability in acidic environments, and large availability. Herein, a simple and affordable hydrothermal route is used for the synthesis of hexagonal WO3 nanorods (average length and diameter of 400 and 50 nm, respectively), whose crystal structure is modified after annealing at 400 °C for 60 min, to obtain a mixed hexagonal/monoclinic crystal structure. These nanostructures were investigated as support for the ultra-low-Pt nanoparticles (0.2-1.13 μg/cm2): decoration occurs by drop casting some drops of a Pt nanoparticle aqueous solution and the electrodes were tested for the HER in acidic environment. Pt-decorated WO3 nanorods were characterized by performing scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), Rutherford backscattering spectrometry (RBS), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and chronopotentiometry. HER catalytic activity is studied as a function of the total Pt nanoparticle loading, thus obtaining an outstanding overpotential of 32 mV at 10 mA/cm2, a Tafel slope of 31 mV/dec, a turn-over frequency of 5 Hz at -15 mV, and a mass activity of 9 A/mg at 10 mA/cm2 for the sample decorated with the highest Pt amount (1.13 μg/cm2). These data show that WO3 nanorods act as excellent supports for the development of an ultra-low-Pt-amount-based cathode for efficient and low-cost electrochemical HER.

Superhydrophobic cellulose paper with sustained antibacterial activity prepared by in-situ growth of carvacrol-loaded zinc-based metal organic framework nanorods for food packaging application

Cellulose paper packaging materials have gained considerable attention as substitutes for petroleum-based plastics owing to their biodegradability, renewability, flexibility, and good mechanical strength. However, high hydrophilicity and the absence of essential antibacterial activity limit their application in food packaging. In this study, a facile and energy-saving method was developed to improve the hydrophobicity of cellulose paper and endow it with a long-acting antibacterial effect by integrating cellulose paper substrate with metal–organic frameworks (MOFs). A dense and homogenous coating of regular hexagonal ZnMOF-74 nanorods was in-situ formed on a paper surface by layer-by-layer assembly followed by low-surface-energy polydimethylsiloxane (PDMS) modification to prepare a superhydrophobic PDMS@(ZnMOF-74)5@paper. Excellent anti-fouling, self-cleaning, and antibacterial adhesion performances were obtained for this superhydrophobic paper. In addition, active carvacrol was loaded into the pores of ZnMOF-74 nanorods on PDMS@(ZnMOF-74)5@paper to combine antibacterial adhesion together with bactericidal ability, ultimately resulting in a completely “bacteria-free” surface and sustained antibacterial performance. The resultant superhydrophobic papers not only showed overall migration values within the limit of 10 mg/dm2 but also good stability against various harsh mechanical, environmental, and chemical treatments. This work gave insights into the potential of in-situ-developed MOFs-dopped coating as a functionally modified platform for preparing active superhydrophobic paper-based packaging.

A study on morphology dependent nanostructured ZnO thin films: An efficient gas sensing response for acetaldehyde

In this work, kinematically grown highly oriented hexagonal ZnO nanorods and nanograined films were fabricated on silicon substrates via pulsed laser deposition method. The structural, morphological, optical properties and the gas sensing studies of ZnO nanostructured thin film were systematically studied. Structural study shows high crystalline films with preferred c-axis orientated nanorods, which are grown over (002) plane nanograined films. Morphological study shows spherical-shaped nanograins and hexagonal vertical rod like structures due to kinematic growth parameters. The optical band gaps of ZnO-NR film at Eg ∼ 3.18 eV and 3.46 eV, depicts greater grain boundary resistance to nanorod resistance. The artificial olfaction effect of ZnO nanorods in detecting acetaldehyde (CH3CHO) is found to be 40% more sensitive than ZnO nanograined films. The ZnO nanorods displays a greater sensitivity response for CH3CHO than other target gases. Transient gas Responsive Resistance (TRR) of ZnO nanorods and nanograined films shows increased sensitivity with higher concentration CH3CHO (10 to 100 ppm) at ambient temperature. The study indicates that ZnO nanorods could be a potential material for the detection of CH3CHO gas at room temperature.