ZnO Nanorod Arrays Research Articles

One-Dimensional ZnO Nanorod Array Grown on Ag Nanowire Mesh/ZnO Composite Seed Layer for H2 Gas Sensing and UV Detection Applications.

Photodetectors and gas sensors are vital in modern technology, spanning from environmental monitoring to biomedical diagnostics. This paper explores the UV detection and gas sensing properties of a zinc oxide (ZnO) nanorod array (ZNA) grown on silver nanowire mesh (AgNM) using a hydrothermal method. We examined the impact of different zinc acetate precursor concentrations on their properties. Results show the AgNM forms a network with high transparency (79%) and low sheet resistance (7.23 Ω/□). A sol-gel ZnO thin film was coated on this mesh, providing a seed layer with a hexagonal wurtzite structure. Increasing the precursor concentration alters the diameter, length, and area density of ZNAs, affecting their performance. The ZNA-AgNM-based photodetector shows enhanced dark current and photocurrent with increasing precursor concentration, achieving a maximum photoresponsivity of 114 A/W at 374 nm and a detectivity of 6.37 × 1014 Jones at 0.05 M zinc acetate. For gas sensing, the resistance of ZNA-AgNM-based sensors decreases with temperature, with the best hydrogen response (2.71) at 300 °C and 0.04 M precursor concentration. These findings highlight the potential of ZNA-AgNM for high-performance UV photodetectors and hydrogen gas sensors, offering an alternative way for the development of future sensing devices with enhanced performance and functionality.

Enhanced ultraviolet photodetection with Ag nanoparticle-decorated ZnO nanowires and core-shell electrodes

Our study presents the synthesis and characterization of one-dimensional (1-D) zinc oxide (ZnO) nanorod (NR) arrays via low-temperature hydrothermal synthesis, followed by surface modification with silver nanoparticles (Ag NPs). Silver nanowires (AgNWs) are potential alternatives to indium-tin oxide, but their poor stability in atmospheric conditions poses a challenge. To address this, we developed ultrathin Ag/ZnO core-shell structured nanowire networks for ultraviolet-photodetectors (UV-PDs). This cost-effective solution process yielded high transmission (77 %) and low sheet resistance (8.3 Ω/sq). We comprehensively investigated surface morphology, crystalline nature, elemental composition, optical properties, and electrical performance of both synthesized nanorod arrays and NW networks. The UV photodetector exhibited a rise time of approximately 1.35 s and a decay time of 8.01 s, both faster than pristine AgNW electrodes. Additionally, the dark current decreased from 9 nA to 3.5 nA after incorporating Ag/ZnO, accompanied by a significant improvement in photocurrent. These results highlight a promising approach for high-performance UV photodetectors, leveraging the stability and conductivity of Ag/ZnO core-shell NW networks.

Hybrid zinc oxide nanocoating on titanium implants: Controlled drug release for enhanced antibacterial and osteogenic performance in infectious conditions

Implant-associated bacterial infections are a primary cause of complications in orthopedic implants, and localized drug delivery represents an effective mitigation strategy. Drawing inspiration from the morphology of desiccated soil, our group has developed an advanced drug-delivery system augmented onto titanium (Ti) plates. This system integrates zinc oxide (ZnO) nanorod arrays with a vancomycin drug layer along with a protective Poly(lactic-co-glycolic acid) (PLGA) coating. The binding between the ZnO nanorods and the drug results in attached drug blocks, isolated by desiccation-like cracks, which are then encapsulated by PLGA to enable sustained drug release. Additionally, the release of zinc ions and the generation of reactive oxygen species (ROS) from the ZnO nanorods enhance the antibacterial efficacy. The antibacterial properties of ZnO nanorod-drug-PLGA system have been validated through both in vitro and in vivo studies. Comprehensive investigations were conducted on the impact of bacterial infections on bone defect regeneration and the role of this drug-delivery system in the healing process. Furthermore, the local immune response was analyzed and the immunomodulatory function of the system was demonstrated. Overall, the findings underscore the superior performance of the ZnO nanorod-drug-PLGA system as an efficient and safe approach to combat implant-associated bacterial infections. Statement of significanceImplant-associated bacterial infections pose a significant clinical challenge, particularly in orthopedic procedures. To address this, we developed an innovative ZnO nanorod-drug-PLGA system for local antibiotic delivery on conventional titanium implants. This system is biodegradable and features a unique desiccation-like structure that enables sustained drug release, along with the active substances released from the ZnO nanorods. In a rat calvarial defect model challenged with S. aureus, our system demonstrated remarkable antibacterial efficacy, significantly enhanced bone defect regeneration, and exhibited local immunomodulatory effects that support both infection control and osteogenesis. These breakthrough findings highlight the substantial clinical potential of this novel drug delivery system and introduce a transformative coating strategy to enhance the functionality of traditional metallic biomaterials.

The effect of seed layer cycles on the structural, optical, and morphological properties of ZnO nanorods.

In this study, ZnO seed layers with different cycles were formed on glass substrates by the sol-gel technique, and ZnO nanorods were grown on them by the hydrothermal method. Morphology and the structural characterization of the seed films and the ZnO nanorods are carried out by field emission scanning electron microscopy (FE-SEM) and x-ray diffraction techniques. In addition, to investigate the effect of seed layer deposition cycles on the optical properties of the ZnO nanorod arrays, UV/visible spectrophotometer and photoluminescence (PL) measurements were performed. The changes in structural and optical parameters such as dislocation density, strain, crystallite size, and optical band gap values on each seed layer deposition cycle were examined. The highest optical band gap and crystallite size were obtained for ZnO nanorods with 4 cycles seed layer as 3.22 eV and 63.6 nm, respectively. Also, in the PL spectrum, the largest ratio of UV-emission region to weak-visible emission region was obtained in ZnO nanorods having 4 cycles. In addition, the glucose detection properties of ZnO nanorods having 4 cycles were investigated using the PL measurements and it was found that UV-emission peak intensity of ZnO nanorods decreased as the glucose concentration increased from 8 to 40 mM. The results show that the number of deposition cycles of the seed layer has a strong influence on the orientation, crystal quality, and optical band gap of the growing ZnO nanorods, as well as significantly affecting their morphological properties. RESEARCH HIGHLIGHTS: High quality ZnO nanorods were grown on glass substrates by hydrothermal method. The effect of ZnO seed layer cycles on the structural, optical, and morphological characteristics of ZnO nanorods grown on were examined. It was found that the number of cycles of the seed layer is a critical parameter for growing quality and well-aligned ZnO nanorods.

3D SERS substrate using silver nanoparticles decorated ZnO nanorods on silicon micropyramids hybrid heterostructure

3D hybrid heterostructure have been fabricated using Ag Nanoparticles decorated ZnO nanorods over textured Silicon Micropyramid for Surface Enhanced Raman Scattering (SERS) applications. Silicon texturing was performed using facile Alkaline texturing route followed by the growth of ZnO nanorods (ZnONR) array on the micropyramids over which, the Ag nanoparticles (AgNPs) were decorated. The phase and the surface of the heterostructure was studied by XRD and Field Emission Scanning Electron Microscope (FESEM), respectively. The SERS performance of the 3D heterostructure was evaluated using Rhodamine 6G (R6G) at various concentrations with a detection limit of 0.1 pM. The superior properties of SiMP/ZnONR/AgNP over ZnONR/AgND heterostructure has also been presented to understand the effect of the 3D pyramidal substrate for superior SERS performance. The recovery of the prepared heterostructure has also been demonstrated by photocatalytic degradation of Rhodamine 6G and Methylene Blue. Our work demonstrates a facile synthesis of 3D SERS heterostructure and sheds light on its superior SERS properties paving ways for wide range of applications in bio-sensors, detection of harmful chemicals, food adulterations, narcotic detection and many more.

Three dimensional noble metal-metal organic framework composite as SERS substrate for efficient capture and detection of pesticides

Hybrids of noble metal and metal-organic framework (MOF) are promising substrates for molecule sensing by surface enhanced Raman scattering (SERS) technique. However, most of these composite SERS substrates are zero-dimensional (0D) or two-dimensional (2D) structures, limiting their efficiency in adsorption and Raman enhancement. In this work, a new three-dimensional (3D) SERS substrate CC/ZnO-Ag@ZIF-8 composed of carbon cloth (CC) supported ZnO nanorod array decorated with AgNPs and coated with ZIF-8 layer was prepared for sensitive detection of pesticide. Compared with common 0D/2D substrates, the synergy of ZnO, AgNPs and MOF in 3D space achieved the highly efficient utilization of each component’s advantages, greatly enhancing the adsorption capacity to analyte and significantly amplifying the EM enhancement effect. Consequently, the 3D SERS substrate showed high SERS sensitivity to pesticide intermediate 4-ATP with a detection of limit (LOD) as low as 10−10 M, which is 3 orders of magnitude lower than its 2D counterpart CC/Ag@ZIF-8, or 2 orders of magnitude lower than that of CC/ZnO-Ag without MOF coating. Additionally, ZIF-8 coating also improves the stability, anti-interference ability and signal consistency of the substrate. Finally, the 3D CC/ZnO-Ag@ZIF-8 was successfully applied to the quantitative analysis of pesticide thiram in real lake water sample, which achieved a linear range of 10−5 to 10−9 M and a LOD of 1 nM. Such 3D noble metal-MOF hybrid SERS substrate with multiple merits in adsorption, Raman enhancement, stability and reproducibility holds great promise in environmental analysis.

Buoyancy-Assisted Fabrication of Liquid Diode: Janus Nanofibrous Membrane for Efficient Wastewater Treatment.

The pressing need for effective methods to separate oil and water in oily wastewater has spurred the development of innovative solutions. This work presents the creation and evaluation of a Janus nanofibrous membrane, also known as the Liquid Diode, developed using electrospinning (e-spinning) and buoyancy-assisted hydrothermal techniques. The membrane features a unique structure: one side is composed of PVDF nanofibers embedded with a GO/TiO2 composite, exhibiting in-air superhydrophobic and superoleophilic properties, while the reverse side consists of PVDF nanofibers with a ZnO nanorod array, demonstrating in-air superhydrophilic and underwater (UW) superoleophobic properties. This distinct asymmetric wettability enables the membrane to effectively separate both water-in-oil (w-in-o) and oil-in-water (o-in-w) emulsions, achieving an impressive liquid flux and separation efficiency (SEff). The in-air superhydrophobic side of the Janus nanofibrous membrane achieves a maximum oil flux (Fo) of 3506 ± 250 L m-2 h-1, while the in-air superhydrophilic side achieves a maximum water flux (Fw) of 1837 ± 150 L m-2 h-1, with SEff exceeding 98% for both sides. Furthermore, the Janus nanofibrous membrane maintained reliable mechanical stability after 10 cycles of sandpaper abrasion test and demonstrated excellent chemical stability when subjected to acidic, alkaline, cold water and hot water conditions for 24 h. These properties, combined with its ability in breaking down of organic contaminants (98% ± 2% in 210 min) and pharmaceutical contaminants (97% ± 2% in 210 min) under visible light, highlight its photocatalytic potential. Additionally, the membrane's antifouling and antibacterial properties suggest long-term and sustainable use in wastewater treatment applications. The synergistic combination of these superior properties positions the Janus nanofibrous membrane as a promising solution for addressing complex challenges in wastewater treatment and environmental remediation.

Synthesis and characterizations of zinc oxide nanorods by cost effective aqueous hydrothermal technique for solid state lighting applications

Zinc oxide (ZnO) is recognized as the most promising and often utilized semiconducting material due to its exceptional physical, chemical, optical, and relatively low-cost production features, as well as its ecologically beneficial nature. ZnO is a prominent candidate owing to its wide band gap (3.37 eV at room temperature) as well as its high exciton binding energy (60 meV) for the next generation of ultraviolet and blue optoelectronic devices. This would be achieved through the development of hybrid heterostructured LED devices with low manufacturing costs by blending gallium nitride (GaN) with zinc oxide (ZnO), which serves as the most efficient opto-electronic device. Due to its high electron mobility, high transparency in the visible wavelength spectrum, and low work function, ZnO is also a highly investigated transparent conducting oxide thin film for several applications. Besides, their incredible optical capabilities, ZnO-based optical devices, such as light-emitting diodes (LEDs) and laser diodes (LDs), have drawn a great deal of interest. This reported research work demonstrates the growth of high-density, high-aspect-ratio ZnO nanorod (NR) arrays on p-type gallium nitride substrates employing low-cost facial aqueous hydrothermal syntheses with optimised growing conditions. Additionally, a top-down chemical etching technique is adapted for fabricating zinc oxide nanotubes. High-quality ZnO nanorods with high intensity that were a few microns long were found across the GaN substrate with FESEM analysis. The chemical composition of the grown nanorods is confirmed with EDAX analysis. The wurtzite crystalline structure and c-axis orientation of the grown ZnO NR-arrays were identified in X-ray diffraction studies. A Schimadzu UV–Vis–NIR spectrophotometer was used to record the optical curve, and the energy gap was determined to be 3.24 eV by plotting the Tauc curve. The good optical quality of the harvested nanorods is ensured by the narrow near-band-edge (NBE) emission at 384 nm and defect emission peaks detected through photoluminescence analyses. Grown specimens are also subjected to Raman spectrum analyses, and the obtained results are presented.

Effect of AZO seed layers on the ultraviolet photoresponse of Ag/ZnO NRs Schottky junctions

Al-doped ZnO (AZO) thin films with different layers were prepared by sol-gel method. The SEM, XRD and AFM for three layers thin films demonstrates high crystal quality and low roughness. ZnO nanorods arrays (NRs) with different AZO seed layers were fabricated using hydrothermal process, and the effect of AZO seed layers on the structural, optical, and electrical characteristics was investigated. When there are three AZO seed layers present, ZnO NRs exhibit fewer surface states, smaller interface charge transfer resistance (Rce = 6.1 × 103Ωand Rct = 6.6 × 106Ω), longer carrier lifetimes (τe = 4.0 ms), higher carrier concentration (ND = 4.73 × 1019 cm−3), and narrower depletion region width W = 3.1 nm. Under weak UV light 381 nm (5.68 mW/cm2) at a bias −0.5 V, Ag/ZnO NRs Schottky devices with three AZO seed layers display a comparatively strong responsivity 34.64 mA/W. Appropriate AZO seed layers are favorable for highly efficient ZnO NRs-based photoelectric conversion devices.

Conformal zinc sulfide coating of vertically aligned ZnO nanorods by two-step hydrothermal synthesis on wide bandgap seed layers for lead-free perovskite solar cells

Vertically aligned ZnO nanorods (NRs) were grown hydrothermally on the wide bandgap (∼3.86 – 4.04 eV) seed layers (SLs) of grain size ∼162 ± 35 nm, prepared using ball-milled derived ZnO powder. The synthesized ZnO NRs were further decorated with ZnS nanocrystals to achieve a ZnO NR-ZnS core–shell (CS)-like nano-scaffolds by a subsequent hydrothermal synthesis at 70 °C for 1 h. UV-Vis-NIR spectroscopy, x-ray diffractometry (XRD), Raman spectroscopy and Field emission scanning electron microscopy (FESEM) coupled with Energy dispersive x-ray spectroscopy (EDX) analyses confirmed the formation of ZnS atop the vertically aligned ZnO NR arrays of ∼1.79 ± 0.17 µm length and ∼165 ± 27 nm diameter. Transmission electron microscopy (TEM)/EDX analyses revealed that vertically aligned ZnO NRs (core dia. ∼181 ± 12 nm) arrays are conformally coated by an ultrathin ZnS (∼25 ± 7 nm) shell layer with a preferential ZnS{111}/ZnO{10-10}-like partial epitaxy. The ZnO NRs exhibited a sharp band edge near ∼384 nm having optical bandgap energy (E g) of ∼3.23 eV. However, the ZnO NR-ZnS CS exhibited double absorption bands at E g ∼ 3.20 eV (ZnO-core) and E g ∼ 3.78 eV (ZnS-shell). The ZnS{111}/ZnO{10-10}-nano-scaffolds could be utilized to facilitate the enhanced absorption of UV photons as well as the radial junction formation between the Pb-free perovskite absorber and ZnS/ZnO NRs layers.

Investigation of structural, optical, surface, electrochemical and corrosion properties of ZnO and AZO nanorod arrays for dye absorption applications

In dye-sensitized solar cells (DSSC), photoanodes have special importance in the processes of dye support, photon absorption and electron transport. ZnO nanorod arrays are promising photoanode materials, but their properties need to be improved by innovative fabrication approaches to improve the performance of ZnO-based DSSCs. In this study, pure and Al-doped ZnO (AZO) nanorod arrays were grown by hydrothermal method onto ZnO seed layers produced by sol-gel spin coating. As far as we know, for the first time in the literature, HMTA-HMDA ligand mixture was used instead of HMTA in the preparation of hydrothermal precursor solutions. To investigate the potential use of ZnO and AZO nanostructured films as photoanodes in DSSCs; their surface, structural and optical properties were examined. Additionally, charge transfer kinetics, corrosion resistance and dye loading capacities were determined by advanced analyzes such as electrochemical impedance spectroscopy, potentiodynamic polarization and adsorption-desorption methods. The supporting HMDA ligand and Al impurity used in the preparation of hydrothermal precursor solutions led potential usages as photoanode of ZnO nanorod arrays to increase by improving their structural, optical, surface, and electrochemical properties, corrosion resistance and dye loading capacities.

In Situ Self-Growth of a ZnO Nanorod Array on Nonwoven Fabrics for Empowering Superhydrophobic and Antibacterial Features

ZnO nanorod nonwoven fabrics (ZNRN) were developed through hydrothermal synthesis to facilitate the prevention of the transmission of respiratory pathogens. The superhydrophobicity and antibacterial properties of ZNRN were improved through the response surface methodology. The synthesized material exhibited significant water repellency, indicated by a water contact angle of 163.9°, and thus demonstrated antibacterial rates of 91.8% for Escherichia coli (E. coli) and 79.75% for Staphylococcus aureus (S. aureus). This indicated that E. coli with thinner peptidoglycan may be more easily killed than S. aureus. This study identified significant effects of synthesis conditions on the antibacterial effectiveness, with comprehensive multivariate analyses elucidating the underlying correlations. In addition, the ZnO nanorod structure of ZNRN was characterized through SEM and XRD analyses. It endows the properties of superhydrophobicity (thus preventing bacteria from adhering to the ZNRN surface) and antibacterial capacity (thus damaging cells through the puncturing of these nanorods). Consequently, the alignment of two such features is desired to help support the development of personal protective equipment, which assists in avoiding the spread of respiratory infections.

Controlled growth of 3D CdS-branched ZnO nanorod arrays for efficient solar driven photoelectrochemical water splitting

While world energy consumption is rising every year, the development of clean and renewable energy sources becomes very important for keeping the standard of living and preserving the environment. Solar driven photoelectrochemical (PEC) water splitting to produce hydrogen and oxygen is a promising method to contribute to the energy increasing demand. The development of the photoelectrode is a key factor for improving the PEC performance. A new morphology of 3D CdS-branched ZnO nanorod array nanocomposite has successfully been synthesized via solution routes as a photoanode. The present nanocomposite provides the highest photocurrent density of 2.5 mA/cm2 at a potential 1.23 V vs. RHE, which is about 83.3 times compared to a photocurrent density of about 0.03 mA/cm2 of the bare ZnO nanorod array photoelectrode. The boost of the PEC performance is improved due to the improvement of light absorption capacity, the enhanced energy band alignment (type-II heterostructure) promoting the charge transfer and separation, and the improvement of the electrode-electrolyte interface reaction kinetics. The result will be useful for further research on energy conversion and energy storage devices.

Ag-modified enhance the performances of ZnO@CFs based omnidirectional photoelectrochemical ultraviolet detectors

There are several prospective applications for omnidirectional ultraviolet (UV) detectors and underwater detection detectors in optical systems and optical fields. In this work, ZnO nanorods arrays were grown on carbon fibers (CFs). An appropriate amount of Ag nanoparticles (NPs) was deposited on the surface of ZnO nanorods by photochemical deposition. This improved the performance of photoelectrochemical (PEC) based UV detectors. Under 365 nm and 10 mW cm−2 UV irradiation, the photocurrent density of the 30s-Ag/ZnO@CFs based PEC UV detector can reach 1.28 mA cm−2, which is about 7 times that of the ZnO@CFs based PEC UV detector, and the rising time is shortened from 0.17 to 0.10 s. The reason is that increased absorption of ultraviolet light induced by the localized surface plasmon resonance. In addition, the detector exhibits a good flexibility and remains flexible after hundreds of bends and twists. Moreover, the detector is responsive in the range of rotation angle from 0° to 360°. It provides an insight to improve the photoelectric performance and underwater omnidirectional detection ability of the PEC UV detector.

Biogenic synthesis of hybrid array of ZnO nanoparticles and nanorods for modeling the surface response behavior of Congo red dye in adsorptive studies

ZnO nanostructures are of substantial interest because of having exclusive potential to inculcate in the plethora of applications. Numbers of reports have been reported in literature depicting the synthesis of ZnO nanostructures with variable dimensions using different precursors with complex mechanism. As per our knowledge, no research work discussing the synthesis of hybrid array of ZnO nanoparticles and nanorods based on single precursor in one pot biogenic reaction has been discoursed so far. Herein, ZnO nanostructures (0-D and 1-D) have been biogenically synthesized at room temperature with average crystallite size of 43.05 nm as depicted by XRD results and further utilized to remove Congo Red dye from aqueous solution. The maximum monolayer adsorption capacity has been found to be 16.6670 mg g−1 at 298 K temperature. Isotherm models and thermodynamic study have suggested the feasible monolayer adsorption of Congo Red dye on ZnO with activation energy of 21.616 kJ mol−1.

Investigation of SERS Studies on Periodic Patterned ZnO Nanorod Array Fabricated Using Silica Inverse Opal Nanostructure as a Template

Investigation of SERS Studies on Periodic Patterned ZnO Nanorod Array Fabricated Using Silica Inverse Opal Nanostructure as a Template

Enhancing Methane Gas Sensing through Defect Engineering in Ag-Ru Co-doped ZnO Nanorods.

Detection of leaks of flammable methane (CH4) gas in a timely manner can mitigate health, safety, and environmental risks. Zinc oxide (ZnO), a polar semiconductor with controllable surface defects, is a promising material for gas sensing. In this study, Ag-Ru co-doped into self-assembled ZnO nanorod arrays (ZnO NRs) was prepared by a one-step hydrothermal method. The Ag-Ru co-doped sample shows a good hydrophobic property as a result of its particular microstructure, which results in high humidity resistance. In addition, oxygen vacancy density significantly increased after Ag-Ru co-doping. Density functional theory (DFT) calculations revealed an exceptionally high charge density accumulated at the Ru sites and the formation of a localized strong electric field, which provides additional energy for the CH4 reaction with •O2- at the surface at room temperature. Optimized AgRu0.025-ZnO demonstrated an outstanding CH4 sensing performance, with a limit of detection (LOD) as low as 2.24 ppm under free-heat and free-light conditions. These findings suggest that introducing defects into the ZnO lattice, such as oxygen vacancies and localized ions, offers a promising approach to improving the gas sensing performance.

Plasmon AgNPs/MoS2/ZnO nanorods array ternary heterojunctions enabling high-efficiency solar-light energy utilization for photocatalysis and recyclable SERS detection

BackgroundSurface-enhanced Raman scattering (SERS) has gained widespread use in molecule-level detection benefiting from its high sensitivity, nondestructive data acquisition, and capacity for providing molecular fingerprint information. However, the strong adhesion of target molecules to the substrate (known as the “memory effect”) inherently hinders the reusability of SERS substrates. Research has shown that self-cleaning SERS substrates based on versatile semiconductor materials with SERS enhancement capabilities and solar photocatalytic properties offer an effective platform for the sensitive detection and degradation of harmful molecules. ResultsIn this research, a resuable SERS-active substrate was facilely fabricated by anchoring silver nanoparticles (AgNPs) to the edges of MoS2 nanosheet decorated on ZnO nanorod arrays (NRAs). This innovative design exhibited a remarkable SERS enhancement factor (EF) of 4.6 × 107 and demonstrated significant solar photocatalytic efficiency. Such superior characteristics of ternary plasma heterojunction were ascribable to the synergistic effect of the “Schottky barrier” and “hot spots” between MoS2 and AgNPs, the inherent chemical enhancement proficiency of the MoS2/ZnO NRAs heterojunction, as well as the ultrafast electron transfer within the ternary heterojunction. SignificanceThe developed ternary heterojunction substrate enabled highly sensitive SERS detection of trace amounts of organic molecules. Moreover, this SERS substrate exhibited self-cleaning and recyclability via solar-light-driven photocatalysis. This bifunctional recyclable SERS substrate proved capable of meeting various requirements for routine monitoring of environmental organic pollutants and provided a robust avenue for advancing energy utilization materials that serve as high-performance SERS sensors and catalysts.

Enhanced photoelectrochemical water splitting by a 3D hierarchical sea urchin-like structure: ZnO nanorod arrays on TiO2 hollow hemisphere

A hierarchical sea urchin-like hybrid metal oxide nanostructure of ZnO nanorods deposited on TiO2 porous hollow hemispheres with a thin zinc titanate interface layer is specifically designed and synthesized to form a combined type I straddling and type II staggered junctions. The HHSs, synthesized by electrospinning, facilitate light trapping and scattering. The ZnO nanorods offer a large surface area for improved surface oxidation kinetics. The interface layer of zinc titanate (ZnTiO3) between the TiO2 HHSs and ZnO nanorods regulates the charge separation in a closely coupled hierarchy structure of ZnO/ZnTiO3/TiO2. The synergistic effects of the improved light trapping, charge separation, and fast surface reaction kinetics result in a superior photoconversion efficiency of 1.07% for the photoelectrochemical water splitting with an outstanding photocurrent density of 2.8 mA cm−2 at 1.23 V versus RHE.

Enhanced thermal conductivity in vertically grown ZnO Nanorods/ Poly(3,4-ethylenedioxithiophene): Poly(4-styrenesulfonate) composite thin films

Herein, we have investigated the thermal properties of compact and vertically grown ZnO nanorods (NRs)/poly(3,4-ethylenedioxithiophene):poly(4-styrenesulfonate) (PEDOT:PSS) composite film. The ZnO NR arrays with length 885 ± 5 nm have been grown using the sol–gel method. Furthermore, composite films of compact-ZnO and ZnO NR with PEDOT:PSS have also been grown. The temperature-dependent thermal conductivity for both the composite films has been investigated in the temperature range of 273–353 K. The thermal conductivity of compact-ZnO/PEDOT:PSS is found to be in between 1.43–1.49 W/mK. The thermal conductivity is found to be enhanced significantly in the case of ZnO NR/PEDOT:PSS composite film.