1D ZnO Nanorods Research Articles

Low-Intensity Light Detection with a High Detectivity Using 2D-Sb2Se3 Nanoflakes on 1D-ZnO Nanorods as Heterojunction Photodetectors.

Multifunctional photodetectors (PDs) with broadband responsivity (R) and specific detectivity (D*) at low light intensities are gaining significant attention. Thus, we report a bilayer PD creatively fabricated by layering two-dimensional (2D) Sb2Se3 nanoflakes (NFs) on one-dimensional (1D) ZnO nanorods (NRs) using simple thermal transfer and hydrothermal processes. The unique coupling of these two layers of materials in a nanostructured form, such as 2D-Sb2Se3 NFs/1D-ZnO NRs, provides an effective large surface area, robust charge transport paths, and light-trapping effects that enhance light harvesting. Furthermore, the combination of both layers can effectively facilitate photoactivity owing to proper band alignment. The as-fabricated device demonstrated superior overall performance in terms of a suitable bandwidth, good R, and high D* under low-intensity light, unlike the single-layered 1D-ZnO NRs and 2D-Sb2Se3 NF structures alone, which had poor detectivity or response in the measured spectral range. The PD demonstrated a spectral photoresponse ranging from ultraviolet (UV) to visible (220-628 nm) light at intensities as low as 0.15 mW·cm-2. The PD yielded a D* value of 3.15 × 1013 Jones (220 nm), which reached up to 5.95 × 1013 Jones in the visible light region (628 nm) at a 3 V bias. This study demonstrated that the 2D-Sb2Se3 NFs/1D-ZnO NRs PD has excellent potential for low-intensity light detection with a broad bandwidth, which is useful for signal communications and optoelectronic systems.

Significant transformation in the point defects evidenced via theoretical simulations supported by Raman and photoluminescence studies in vertically grown 1D ZnO nanorods triggered by titanium ion implantation

One-dimensional ZnO exhibits fascinating electrical and optical properties enabling remarkable performance in photonics, sensors, optics and photovoltaic devices. Stopping and Range of Ions in Matter (SRIM) simulations for Ti ion implantation into ZnO nanorods (NRs) at varying fluences (1 × 1014 to 5 × 1015 ions/cm2) at 100 keV results in an electron to nuclear energy loss ratio (Se/Sn) of 0.22, with maximum Ti ion occurrence and point defects within 100 nm along the NRs. Theoretical predictions align with experimental results especially of Raman scattering, X-ray photoelectron spectroscopy, and photoluminescence confirming an increase in the structural point defects with escalating Ti fluence. The pristine ZnO NRs initially exhibit yellow-orange photoluminescence emission. Following implantation, this emission transforms into green, which is due to zinc vacancies. The agreement between theoretical simulations and experimental results affirms the validity of our investigation into the formation and progression of point defects in Ti-implanted ZnO NRs.

Two Significant Factors Affecting the Dimensions of the ZnO Nanorods During Chemical Bath Deposition: Precursor Solution Concentration and HMTA Content

The effects of zinc ion concentration and hexamethylene tetramine (HMTA) content of the aqueous precursor solution on the aspect ratios of the one-dimensional (1D) ZnO nanorods during chemical bath deposition (CBD) were investigated. The ZnO nanorods were grown on these seeded substrates by the low-temperature CBD method at 95 °C for 5 h. In the first part of this investigation the zinc nitrate hexahydrate (ZNH) to HMTA molar ratio was kept constant at a ratio of 1:1 for each of the CBD solutions prepared with different Zn^(+2) ion concentrations of 0.025, 0.035, 0.050, and 0.075 M. The number densities of the nanorods (i.e., number of nanorods per unit area) were increased with the increasing concentration. In the second part, the ZNH to HMTA molar ratio was varied to differ from the 1:1 value and, in turn, to obtain the precursor solutions relatively rich in Zn^(+2) or OH^-ions. Here, the concentration of the precursor solution was kept constant at 0.05 M. The lateral growth perpendicular to the c-axis of the ZnO nanorods was found to be suppressed with the increasing HMTA content (e.g., for the ZNH to HMTA molar ratio of 0.4: 1) due to its capping effect. However, the precursor solution containing an excessive amount of HMTA led to a decrease in the probability of crystal growth, which has been attributed to the OH^- ion enrichment.

Efficient 1D ZnO/Cu2S heterostructure photocatalyst on topological Ag molded PVDF polymer fiber matrix for photoelectrochemical hydrogen evolution applications

A heterostructure semiconductor photo-electrocatalyst ZnO/Cu2S-loaded PVDF polymer matrix is used for solar water splitting. Herein, Ag nanoparticle-casted electrospun PVDF polymer matrix fibers have been used as a platform to fabricate the 1D ZnO nanorods as a photo-electrocatalyst. The Cu2S nanoparticles passivated on the 1D ZnO nanoarray show a two-fold enhancement of the photoelectrochemical hydrogen evolution. The conducting Ag nanoparticles sensitized PVDF, enhancing the conductance, and synergistically contributed to the water splitting under white light illumination. The PVDF/Ag/ZnO/Cu2S photoanode demonstrated photoelectrochemical water splitting. Ag nanoparticles (Ag NP), 1D nanostructures, and Cu2S narrowband gap semiconductors integrated into the photoanode accelerate the oxidation of the water through more visible absorption and high charge carrier transport. The PVDF/Ag/ZnO/Cu2S photoanode generates a stable saturated photocurrent density of 0.62 mA/cm2 in the −0.2 to 0.4 V vs. Ag/AgCl potential window. The chemically inert PVDF fibers with an Ag metal surface show a low onset potential and a charge transfer resistance of 844 Ohm/cm2 with a 0.42% photon to electron conversion efficiency for solar water splitting. Solar water oxidation has been demonstrated under unbiased conditions.

The improvement of polymer photodetector based on 1D-ZnO nanorod arrays/0D-ZnO quantum dots composite film

Polymer photodetectors have been paid much attention in the field of wearable sensing devices and solar cells, due to their excellent performance. In this work, self-powered n-Zinc Oxide/p-Poly(3-hexylthiophene) (n-ZnO/p-P3HT) inorganic-organic hybrid heterojunction photodetectors were successfully fabricated. The polymer P3HT as active layer can efficiently response for visible light. The n-ZnO as light scattering and electron transport layer was composited by 1D-ZnO nanorod arrays (NRAs) and 0D-ZnO quantum dots (QDs) hybridization structure. Compared with the reference device of ZnO NRAs/P3HT, the ZnO NRAs/6 Layers ZnO QDs/P3HT device achieves the best performance, and it shows a photo-to-dark current ratio of 9058, a responsivity of 15 mA/W and a normalized detection of 2.08 × 1011 Jones under 440 nm light illumination and zero-voltage bias. The present work provides a new way to optimize the performance of polymer photodetectors.

Facile synthesis of 2D acid-etched g-C3N4 nanosheets with 1D ZnO nanorods as a promising electrode material for supercapacitor

A low-cost, non-toxic nanocomposite of two-dimensional (2D) nanosheets of acid-etched graphitic carbon nitride (TGCN) and one-dimensional (1D) nanorods of zinc oxide (ZnO NRs) is prepared using one-step calcination method. The average size and diameter of ZnO nanorods in TGCN/ZnO (T-ZnO) nanocomposite is reduced to 0.5 and 0.73 times than pristine ZnO NRs, respectively. After the acid-etching process, the size of the T-ZnO nanocomposite is further reduced which enhanced its specific surface area to 16.82 m2/g as compared to pristine ZnO NRs (3.56 m2/g). T-ZnO NRs shows a specific capacitance of 398.47 F/g using 0.5 M H2SO4 which is higher as compared to T-ZnO NRs using 0.5 M Na2SO4 (278.16 F/g) and 6 M KOH (106.10 F/g). Using Electrochemical impedance spectroscopy, diffusion coefficient (D) value 1.85 × 10−11 is obtained for T-ZnO NRs (0.5 M H2SO4). T-ZnO NRs also exhibits a higher specific capacitance of 311.80 F/g at 1 A/g using 0.5 M H2SO4. The nanocomposite shows superior energy density of 97.43 Wh/kg at 750 W/kg of power density. The superior capacitance retention (>95 %) and stable coulombic efficiency (>80 %) of T-ZnO NRs enables the nanocomposite for practical applications in energy storage devices. The electric double layer (EDL) and pseudocapacitive (PC) contribution of 6.04 % and 93.96 % to the total specific capacitance of T-ZnO NRs is evaluated using Trasatti method. The capacitive and diffusion-controlled contribution is also investigated for T-ZnO NRs using Dunn's method. The practical aspect of a supercapacitor using leakage current and self-discharge is also tested for the T-ZnO NRs. T-ZnO NRs is a promising energy storage material to fill the gap in the ongoing energy crisis.

Growth of highly aligned ZnO nanorod arrays on zinc plates: Morphological and structural characterization

In this work, uniform and highly aligned ZnO nanorod arrays were simply synthesized on zinc plates by hydrothermal method using zinc–ammonia complex solution. Effects of ZnO seed layer formation, Zn(NO3)2 concentration and NH3/Zn(NO3)2 mole ratio (R) in the reaction medium on the morphology and crystal structure of nanorods were investigated in detail. ZnO nanorods grown on zinc surfaces were highly crystalline and had a hexagonal wurtzite structure, as revealed by XRD analysis. In addition, the dominant crystal growth direction was in c-axis, indicating the verticality of the nanorods. SEM images showed that one-dimensional (1D) ZnO nanorods with high verticality and number density were synthesized on seeded plates whereas randomly oriented arrays were grown on non-seeded surfaces. Increase in the Zn2+ concentration changed the top ends of the rods from tapering to hexagonal ends; and also led to an increase in the average size and verticality of the nanorods. The increase in R value (or i.e., amount of NH3) caused the rods to misalign on the surface and decrease in size. The size of well-aligned nanorods can be adjusted from 50 to 260 nm in diameter and 0.11 to 6 m in length by changing the reaction parameters, implying their large potential to be used in photocatalytic and also in electronic applications.

Effects of Hydrothermal Reaction Time on the Structure and Optical Properties of ZnO/Graphene Oxide Nanocomposites

In this research, ZnO/GO nanocomposites were successfully synthesized by a simple hydrothermal method using graphene oxide (GO) and zinc acetate dihydrate (Zn(CH3COO)2.2H2O) as the reactants. The effect of the hydrothermal reaction time on the structure and optical property of the ZnO/GO was systematically investigated. The structure, morphology and chemical composition of the samples were measured by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and Raman and Fourier transform infrared (FTIR) spectroscopy, while the optical properties were measured using photoluminescence spectroscopy. The synthesized products consisted of large quantities of one-dimensional (1D) ZnO nanorods (NRs), which were dispersed uniformly on the GO surface. The XRD and Raman results reveal that the ZnO NRs in the fabricated samples had a hexagonal wurtzite structure with high crystalline quality. The FESEM and TEM images reveal that ZnO NRs with an average diameter in the range of ~85–270 nm and length in the range of ~0.3–6 μm were covered with GO sheets. Additionally, it was found that the crystallographic orientation of ZnO NRs was dependent not only on the hydrothermal reaction time but also on the presence of GO in the nanocomposites. However, the addition of GO did not affect the stoichiometric ratio and the crystal structure of ZnO NRs. The room-temperature PL results indicated that, compared to those of pure ZnO, the luminescence of the GO/ZnO nanocomposites was suppressed and shifted towards a higher wavelength (red shift), which was attributed to the incorporation of ZnO NRs within the GO matrix and the formation of a C-O-Zn chemical bond in the nanocomposites. The hydrothermal technique is considered one of the best routes due to its low cost, high growth rates, low-temperature synthesis, controllable crystallographic orientation, particle size, as well as morphology.

Intimate coupling of 3D MnFe2O4 cubes on 1D ZnO nanorods for sustainable photocatalysis under visible light: Computational analysis of reactive sites and degradation pathway

BackgroundIn recent times, the discharge of wastewater containing aromatic compounds has serious effects on human health and the environment. Thus the fabrication of an efficient and visible light-active nano photocatalyst offers an optimum and sustainable solution. MethodIn this study, ZnO/MnFe2O4 nanocatalyst was fabricated by the ultrasonication mediated reflux method. The fabricated nanomaterials were characterized with SEM, TEM, XRD, XPS, UV-visible DRS, BET, EIS, PL, ESR analysis. The ensued nanocomposite (NCs) was employed for the photocatalytic removal of methylene blue (MB) dye. Significant findingsThe photocatalytic efficiency of ZnO/MnFe2O4 NCs for the removal of MB was 85% which was higher than the efficiency of both the individual semiconductors ZnO (63%) and MnFe2O4 (69%). The rate constant for the photocatalytic removal of MB by ZnO/MnFe2O4 NCs (0.07 min−1) was 12 times higher than the ZnO (0.006 min−1) and 1.75 times higher than MnFe2O4 (0.04 min−1). The boosted photocatalytic performance of ZnO/MnFe2O4 was attributed to the higher surface area (204.559 m2/g) with more active sites compared to ZnO (188.212 m2/g) and MnFe2O4 (106.893 m2/g). The as-fabricated ZnO/MnFe2O4 NCs possess excellent stability as affirmed by recycle test and the analysis of reused XRD. The major part of the degradation of MB was performed by •OH− radicals which was confirmed by scavenging test. The overall results suggest that the fabricated ZnO/MnFe2O4 is an active material for photocatalytic applications.

Synergism induced sensitive SERS sensing to detect 2,6-Di-t-butyl-p-hydroxytoluene (BHT) with silver nanotriangles sensitized ZnO nanorod arrays for food security applications

By the over exploitation of synthetic phenolic antioxidants [2,6-Di-t-butyl-p-hydroxytoluene (BHT)] alarm the society with greater health risk urge for careful monitoring and assessment. To accomplish the objective, surface enhanced Raman scattering (SERS) is explored as prominent technique for direct detection of food additives with the development of semiconductor/metallic junction (1D ZnO nanorods/ silver nanotriangles) sensor on stainless steel substrate. Stainless steel substrate offers cost-effective, highly thermal resistant, improves Raman signal strength and suppresses background signal fluorescence. The influence of growth parameters with respect to length of the nanorods (ZNR) are optimized. Silver nanotriangles (AgT) are sensitized upon the surface of ZnO nanorods (ZNR/AgT). The hybrid nanostructures structural, morphology and optical property are discussed in detail. Highly sensitive sensor was identified with ZnO nanorod length 0.49 µm attained at growth interval of 3 h (Z3/AgT). The underlying mechanisms responsible for ultra-sensitivity is highlighted with the point of synergism. With synergistic mechanism, ∼5.2-fold increment in sensitivity is attained. The fabricated Z3/AgT sensor portrays high stability, vastly reusable, extreme uniformity (RSD values -8.3%) as well ultrasensitive in sensing the food additive BHT at very low concentration (0.1 ng/mL). The developed sensor is highly suitable for onsite monitoring of foodstuffs to conserve the food safety.

Determining the structure-antibacterial properties relationship and bacterial inactivation kinetics in different morphological-controlled ZnO nanoarchitectures for wastewater applications

This study aimed to systematically evaluate and determine the specific roles of reactive oxygen species (ROS) and Zn2+ ions in governing the antibacterial properties of different ZnO nanoarchitectures. This could differ greatly on model bacteria under different irradiation conditions and affects on the design and scale-up of ZnO-based photocatalytic system for wastewater applications. Various ZnO nanostructures were synthesized, characterised and systematically evaluated for their antibacterial properties on both Gram-positive and Gram-negative bacteria under dark, UV-light, and simulated solar irradiation conditions. Results showed that the 1D-ZnO nanorods possessed the highest photo-deactivation ability with a 3.5-log reduction for B. subtilis and a 4.2-log reduction for E. coli under UV light conditions. This is precisely linked to the 1D rod-like ZnO nanostructures with a higher exposed polar surface that favours the dissolution kinetics of Zn2+ ions. Besides, the surface oxygen vacancies were found to be strongly correlated to the intracellular ROS concentration that imparts bactericidal effect at different extents depending on the ZnO nanostructures used. The photo-deactivation kinetics were found to be best-fitted using the empirical Hom model, as it could represent the non-linear bacterial inactivation kinetics profile with a prolonged tailing characteristic. Finally, the Friedman non-parametric test showed that all experimental datasets for B. subtilis and E. coli surviving cases were significantly different (p-value < 0.05). The post-hoc approach indicated that the Zn2+ ions dissolution was the fundamental factor in dictating the antibacterial properties in different ZnO nanostructures.

Novel 0D/1D ZnBi2O4/ZnO S-scheme photocatalyst for hydrogen production and BPA removal

Developing interfacial connections is one of the breakthrough strategies to improve the photocatalytic activity. Herein, ZnBi2O4 nanoparticles-ZnO nanorods heterojunction was successfully synthesized and used, as a dual-function photocatalyst, for photocatalytic degradation of Bisphenol A and hydrogen production with improved photocatalytic activity under simulated sunlight irradiation. The highest H2 production (3.44 mmol g−1 h−1) was obtained for ZnO-20 wt% ZnBi2O4 sample, which is around 12.7 times higher than pure ZnO. According to the HRTEM result, the intimate interfacial connections are formed between ZnO and ZnBi2O4 which could act as trapping centers for charge carriers and results in the boosted photocatalytic activity. Further, a high aspect ratio of 1D ZnO nanorods and small size of 0D ZnBi2O4 nanoparticles (~10 nm) increases the number of interfacial contacts and thus the charge carriers’ recombination was suppressed more efficiently. Based on the trapping experiments, ESR and Mott-Schottky analysis, ZnBi2O4–ZnO hybrid photocatalyst followed the S-scheme charge transfer mechanism.

Performance Investigation of a Perovskite Solar Cell with TiO2 and One Dimensional ZnO Nanorods as Electron Transport Layers

Organic-inorganic halide perovskite thin film perovskite solar cells are gaining much attention, in recent years. Designing proper electron transport layer (ETL) and hole transport layer (HTL) with high quality to achieve devices with higher efficiency are fundamental. One dimensional (1D) nanostructures are newly introduced materials with high mobility and low recombination rate, which may improve the device performance. In this paper, 1D ZnO nanorods (ZnO-NRs) as well as planar TiO2 are considered as the ETL of the device and their electrical performance are compared with different HTL materials in Sn- and Pb- perovskite. In addition, impact of critical design parameters including absorber thickness, interface defect density, back contact electrode materials on the performance of the device are comprehensively assessed. In this work, the simulations have been carries out using a 1D Solar Cell Capacitance Simulator (SCAPS-1D). The results show that in Sn- perovskite, ZnO-NRs has superior performance in comparison with TiO2 with maximum photon conversion efficiency (PCE) of 16.7 % and short circuit current density of 30.21(mA/cm2). However, in terms of Pb-perovskite planar TiO2 has given the best performance with PCE of 19.6%. The results in this paper pave the way for introducing inexpensive high performance solar cell.

Engineering paper-based visible light-responsive Sn-self doped domed SnO2 nanotubes for ultrasensitive photoelectrochemical sensor

Exploring novel photoactive materials with high photoelectric conversion efficiency plays a crucial role in enhancing the analytical performance of paper-based photoelectrochemical (PEC) biosensor. SnO2, which possesses higher photostability and electron mobility, can be regarded as a promising photoactive material. Herein, paper-based one dimensional (1D) domed SnO2 nanotubes (NTs) have been developed with the template-consumption strategy. What’s more, their growth mechanism has also been proposed based on the controllable experiments. At first, the paper-based 1D ZnO nanorods (NRs) as the typical amphoteric oxide are prepared and serve as the sacrifice templates which can be etched by the generated alkaline environment during the formation of SnO2. At a certain stage, all the ZnO NRs can be completely etched by controlling the experimental conditions, resulting in the forming of vertically distributed hollow SnO2 NTs. Furthermore, the Sn self-doping strategy is also proposed to suppress the recombination of charge carriers and broaden the light response range by introducing the impurity energy levels. Profiting from such doping strategy, the prominent photocurrent signal is obtained compared with pure paper-based SnO2 NTs. Ultimately, an innovative visible light responsive paper-based Sn-doping SnO2-x NTs are developed and employed as the photoelectrode for the PEC biosensor using the alpha fetoprotein (AFP) as the model analyte. Under the optimal conditions, the ultrasensitive AFP sensing is realized with the linear range and detection limitation of 10 pg mL-1 to 200 ng mL-1 and 3.84 pg mL-1, respectively. This work provides a judiciously strategy for developing novel photoactive materials for paper-based PEC bioanalysis.

Preparation of novel ternary g-C3N4/WO3/ZnO nanocomposite adsorbent with highly effective imidacloprid removal: optimization design and a controllable systematic study

In this study, a novel g-C3N4/WO3/ZnO nanocomposite was successfully synthesized from two-dimensional (2D) g-C3N4 and WO3 nanosheets and one-dimensional (1D) ZnO nanorods. These nanostructures were characterized by the related analyses of field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, mapping, X-ray diffraction, and Fourier transform infrared spectroscopy. The obtained results further demonstrated the successful synthesis of the ternary heterostructure. The final productions were used as an effective adsorbent for imidacloprid pesticide removal from aqueous solution. Also, 2k−1 factorial design was applied to systematic study the effects of various experimental parameters such as the amount of adsorbent, imidacloprid concentration, contact time, and pH on the adsorption behaviors. According to the results obtained from the analysis of variance, these experimental parameters have significant effects on the imidacloprid adsorption efficiency. Also, response surface methodology was used to attain the best optimization procedure of imidacloprid adsorption. The results showed that g-C3N4/WO3/ZnO nanocomposite has a significant potential for imidacloprid removal with an efficiency of 99.9%. The appropriate kinetic model for imidacloprid adsorption on the g-C3N4/WO3/ZnO nanocomposite was pseudo-second-order kinetic models. Also, Freundlich isotherm was fitted for performing the adsorption process. The nanocomposite developed in this study and also the optimization procedure can be used as a novel strategy in the green future.

Engineering of mono-dispersed mesoporous TiO2 over 1-D nanorods for water purification under visible light irradiation.

Herein we synthesized a novel structure of mesoporous TiO2 decorated on 1D ZnO nanorods for environmental remediation. The effect of mesoporous TiO2 over 1D nanorods were investigated. The phase transitions of nanocomposite were confirmed by powder diffraction analysis. The morphological investigation of synthesized TiO2/ZnO catalyst revealed that the TiO2 are in porous in nature which covered the surface of 1D nanorods. The size of mesoporous TiO2 nanoparticles was about 10-15 nm. The chemical composition and elemental mapping results clearly evident that the presence of ZnO and TiO2 is distributed uniformly on ZnO nanorods. TiO2/ZnO nanocomposite shows enhanced activity which degrades in 14 min under visible light irradiation. TiO2/ZnO catalyst with 5 wt % exhibited the high photocatalytic activity (0.1882 min-1). It is proposed that a synergistic interaction between ZnO and TiO2 leads to a charge separation which leads to the enhanced activity.

Photoelectrochemical Bioanalyte Sensor Based on Engineered One-Dimensional Nanostructured Oxide

Photoelectrochemical (PEC) non-enzymatic sensing systems are beneficial for the detection of low concentrations of biological molecules. Among different potential nanostructured materials, one dimensional TiO2 and ZnO nanorods are promising semi-conductor which can be successfully applied in many photoelectrochemical applications, mainly due to their photoactive properties, and long-term stability. In spite of their advantages, the wide band gap of 1D TiO2 and ZnO along with their high recombination rate confine their applications dramatically. These properties, prevent 1D TiO2 and ZnO from absorbing visible light; therefore, the semiconductor is only photoactive in the UV range. Here, we describe novel non-enzymatic sunlight-driven PEC sensors based on a modified 1D TiO2 nanorod array with cocatalyst and 1D ZnO core-shell structure for the aim of improved PEC non-enzymatic detection of glucose and H2O2, respectively. The 1D TiO2 and ZnO nanorods array were prepared through facile hydrothermal at and electrodeposition methods, respectively. The modified electrodes were characterized through FESEM, HRTEM, XRD, and UV-vis spectroscopy. The novel 1D TiO2 and 1D ZnO@TiO2 core shell electrodes exhibited enhanced PEC sensing properties with a low limit of detection and a high sensitivity, over a linear range of 0.1 – 1000 nM of glucose and 1 pM-100 mM of H2O2 in PBS. Additionally, the sensor displayed high selectivity, high stability, and high reproducibility. Overall, our engineered PEC sensor demonstrated ultrasensitive detection of glucose and H2O2 and a capable platform for continued development into the field of PEC non-enzymatic sensors.

Vertically Coupling ZnO Nanorods onto MoS2 Flakes for Optical Gas Sensing

Hybrid structures composed of layered one-dimensional (1D) and two-dimensional (2D) materials opened new perspectives and opportunities through the build-up of hetero-junctions with versatile layered structures and led to fascinating fundamental phenomena and advanced devices. We succeeded in depositing by magnetron sputtering vertically aligned 1D ZnO nanorods on 2D MoS2 flakes obtained by exfoliation, preserving the structure of the 2D materials. The photoluminescence (PL) optical properties of the hybrid structure were assessed towards developing a contactless optical chemical sensor.

Wet chemical epitaxial growth of a cactus-like CuFeO2/ZnO heterojunction for improved photocatalysis.

Herein, a wet chemical epitaxial growth method was employed to fabricate a cactus-like CuFeO2/ZnO heterojunction for the photocatalytic reduction of benzaldehyde to benzyl alcohol. The 1D ZnO nanorods in the heterojunction make contact with the 2D CuFeO2 nanoflakes at the atomic level, therefore providing a fast charge transfer channel along the direction parallel to the CuFeO2c-axis, leading to efficient charge separation and improved photocatalytic performance.

Simplified patterning process for the selective 1D ZnO nanorods growth

A novel patterning method for the selective growth of ZnO nanorods has been developed, which can avoid any etching steps and longtime lift-off processes. In the simplified process, the deposition of a titanium buffer layer is omitted, and a 50 nm ZnO thin-film seed layer is deposited by e-beam evaporation directly onto the silicon patterned with the photoresist. The omitted titanium buffer layer has been observed to result in the absence of the ZnO seed layer on the photoresist. Then, the ZnO nanorods with diameters ranging from 50 to 500 nm have been found to grow hydrothermally only on the regions without the photoresist. The photoresist remains on the substrate after the hydrothermal growth, which can protect areas from the polluted solution and unwanted nanorods. After all processes, the photoresist can be removed easily by the solvent without any unwanted damage of nanorods. With this simplified method, ZnO nanorods can be synthesized and patterned with only one step of lithography, which can be used for novel ZnO based devices.