Zn Ratio Research Articles

Comparative Study of Atomic Layer Deposition Supercycle Design Effects on Reliability in Heterogeneous IGZO Channel TFTs

Oxide semiconductor thin-film transistors (TFTs) are promising candidates for application in display backplanes and memory devices. To ensure both high performance and stable electrical properties of oxide TFTs over long-term use, superior mobility and device stability need to be obtained. In this regard, atomic layer deposition (ALD) has gained attention as a facile method for obtaining conformal oxide films under defect-free conditions and adjusting the composition or distribution for targeted TFT performance. Here, we propose that, even with the same bulk composition, variations in the local composition using an ALD supercycle design can significantly affect the TFT performance, particularly the bias-temperature stability. To ascertain the influence of the local cation distribution on the performance, we compared two supercycle designs by reversing the sub-cycles of indium, gallium, and zinc with identical bulk In–Ga–Zn ratios. Despite minimal changes in the electrical characteristics, such as the mobility and threshold voltage, of the two TFTs designed with ALD supercycles, there was a significant difference in their reliability. Devices with an indium-rich IGZO active layer on the back channel exhibited a hump phenomenon and approximately five times greater Vth degradation (ΔVth: -0.67 V to -3.36 V). By conducting an additional case study of IGZO TFTs and film analysis, we confirmed that mobility is largely governed by the bulk composition, whereas the local surface composition, serving as the back channel, is the key to reliability. The device performance results could be confirmed through the surface and bulk analyses of heterogeneous films engineered through the ALD supercycle design. Furthermore, it has been proposed that optimizing the ALD supercycle design is the key to obtaining high-performance oxide semiconductor TFTs.

Structural, Morphological, and Optical Properties of Nano- and Micro-Structures of ZnO Obtained by the Vapor–Solid Method at Atmospheric Pressure and Photocatalytic Activity

Micro- and nano-structures of ZnO were synthesized by the vapor–solid method at 600, 700, and 800 °C in atmospheres of Ar and air, at atmospheric pressure. The structural characterization XRD shows that the nano-structures synthesized in air atmosphere at 600 °C, while diffraction peaks were found due to Zn because the presence of metallic Zn remains on the surface of the pellet. SEM images show that the morphologies range from nano-wires to micro-tubes. When cathodoluminescence is measured in micro-tubes, there is a shift of the near-band edge of the ZnO toward red; this is due to structural defects in the ZnO network. This result is corroborated with panchromatic CL measurements, which exhibit a difference in brightness between the micro-tubes. Furthermore, EDS measurements show an atomic quantity ratio of Zn:O that differs from the stoichiometric composition in the micro-tubes. The photocatalytic activity of three types of structures—nano-wires, micro-tubes, and micro-rods under UV irradiation using methylene blue as a model pollutant—were evaluated. The best response was obtained for nanowires, not only because they have a larger surface area but also because of the present defects.

Sonophotopythochemical Functionalization of Graphene Oxide - Al - Zn Bimetal Nanocomposite for Corrosion Inhibition

The corrosion performance of steel in the marine environment has been a primary concern of engineers and garnered significant interest due to its industrial significance. To address this concern, the incorporation of green corrosion inhibitors as coating materials in mild steel has been extensively studied recently. This paper explores the synthesis of graphene doped with bimetal aluminum-zinc (GO-Al-Zn) nanocomposites via sonophoto-phytochemical functionalization using Chayote (Sechium edule) leaf extract as the doping agent to produce a corrosion inhibitor. The synthesized nanocomposites were characterized using FTIR, SEM-EDS, XRD, and TEM. The optimal nanocomposite, with a 55% Al - 45% Zn ratio, demonstrated successful bio-reduction, good dispersion, reduced particle size, and a rhombohedral crystal structure. When incorporated into an epoxy coating and applied to mild steel, the GO - 55% Al - 45% Zn coating achieved a high corrosion inhibition efficiency of 98.06% (gravimetric method) and 98.45% (electrochemical method) in 3.5 wt% NaCl solution. This study highlights the promising potential of GO - 55% Al - 45% Zn nanocomposite as an eco-friendly corrosion inhibitor. Future research should explore optimizing the functionalization process and exploring long-term environmental stability.

Algorithm-Driven Robotic Discovery of Polyoxometalate-Scaffolding Metal-Organic Frameworks.

The experimental exploration of the chemical space of crystalline materials, especially metal-organic frameworks (MOFs), requires multiparameter control of a large set of reactions, which is unavoidably time-consuming and labor-intensive when performed manually. To accelerate the rate of material discovery while maintaining high reproducibility, we developed a machine learning algorithm integrated with a robotic synthesis platform for closed-loop exploration of the chemical space for polyoxometalate-scaffolding metal-organic frameworks (POMOFs). The eXtreme Gradient Boosting (XGBoost) model was optimized by using updating data obtained from the uncertainty feedback experiments and a multiclass classification extension based on the POMOF classification from their chemical constitution. The digital signatures for the robotic synthesis of POMOFs were represented by the universal chemical description language (χDL) to precisely record the synthetic steps and enhance the reproducibility. Nine novel POMOFs including one with mixed ligands derived from individual ligands through the imidization reaction of POM amine derivatives with various aldehydes have been discovered with a good repeatability. In addition, chemical space maps were plotted based on the XGBoost models whose F1 scores are above 0.8. Furthermore, the electrochemical properties of the synthesized POMOFs indicate superior electron transfer compared to the molecular POMs and the direct effect of the ratio of Zn, the type of ligands used, and the topology structures in POMOFs for modulating electron transfer abilities.

On the secondary promotion effect of Al and Ga on Cu/ZnO methanol synthesis catalysts

The structural and electronic effect of Al and Ga as ternary metals in Cu/ZnO catalysts for the methanol synthesis was examined. For this purpose, three zincian malachite-derived catalysts with the nominal Cu:Zn ratio of 70:30 were synthesized: an unpromoted binary catalyst (CZ) and two ternary catalysts with either 3 mol% Al (CZA) or Ga (CZG). Both Al and Ga showed a strong impact on the catalyst’s structure. Alongside the catalyst’s evolution from the co-precipitated precursors phase to the activated and reduced state, an improved microstructure and an increased BET surface area were found for the secondary promotor (Al or Ga) containing catalysts. Moreover, a sequence of chemisorption experiments allowed us to quantify and differentiate between Cusurf and Znred surface species in the activated catalysts. Considering the specific copper surface areas, DRIFTS data and catalytic results, an additional electronic promotion of Al and Ga is proposed. As demonstrated by Ga K-edge XANES, this promotion effect is related to doping of the ZnO support and enhances the reducibility of ZnO to form more Znred sites. This effect is stronger for Al leading to a more pronounced Znred overlayer on the Cu surface due to SMSI. In methanol synthesis, this results in a performance order CZA > CZG > CZ.

Bimetallic MnZn-MOF-74 with enhanced percentage of MnIII: Efficiently catalytic activity for direct oxidative carboxylation of olefins to cyclic carbonates under mild and solvent-free condition

Multi-functional MOF catalyst with oxidative- and acid- centers showed potential in olefins oxidative carboxylation to cyclic carbonates directly. In this work, a series of bimetallic MnZn-MOF-74 with different molar ratios of Mn and Zn were synthesized successfully through a one-pot facile method. Thoroughly characterization indicated that the existence of Zn regulated the valance state distribution of Mn in the obtained MnZn-MOF-74. Mn99.3Zn0.7-MOF-74 with the highest ratio of MnIII (61.3 %) performed the most efficient activity for olefin direct tandem oxidative carboxylation reaction using aqueous tert-butyl hydroperoxide oxidant under solvent-free condition of 90 °C, 1.0 MPa CO2 and 4 h. Mn99.3Zn0.7-MOF-74 also showed satisfactory versatility and recyclability. Based on the experiments, a feasible mechanism was presented. Thanks to the high ratio of active MnIII as main oxidative center, the coordination unsaturated bimetal Mn and Zn as Lewis-acid sites, O2– of metal − O as Lewis-base sites and combined effect with Bu4NBr cocatalyst, Mn99.3Zn0.7-MOF-74 presented efficient performance for the direct synthesis of cyclic carbonates from olefins. The metal Zn in MOF can regulate the valance state distribution of Mn and result in efficient catalytic property, presenting a potential avenue for direct oxidative carboxylation reaction of olefins to cyclic carbonates synthesis.

Realization of grain growth and suppressed bulk defects for efficient solution-processed Cu2ZnSn (S, Se)4 solar cells via co-doping strategy

Environmentally benign and earth-abundant constituent’s kieserite Cu2ZnSn (S, Se)4 (Cotises) is considered as a hopeful photovoltaic material. Unfortunately, the severe tail state caused by various harmful deep defects in CZTSSe absorber prevents further development of its device efficiency. Here, we report firstly that the Co was incorporated into CZTSSe films to form the Cu2CoxZn1-xSn (S, Se)4 (CCZTSSe) films using a two-step annealing and solution-processing technique method. Through optimized the Co/(Co+Zn) ratio, the CCZTSSe film has excellent good surface morphology and single-phase composition. Appropriate amount of Co elements replacing Zn elements in CZTSSe films can effectively reduce the degree of Cu-Zn disorder, thus inhibiting [2CuZn+SnZn] defect clusters and CuZn defects. The detrimental deep defects located in the film were effectively passivated to reduce electrostatic potential fluctuations, resulting in relief of the trailing state. Therefore, a champion device having an efficiency of 7.50 % with a fill factor (FF) of 61.00 % was achieved from CCZTSSe with 3 % Co content. This work provides new insights into the impacts of Co doping in CZTSSe by a solution processed method and offers a deeper comprehension of the origin of the efficiency enhancement of CCZTSSe devices.

Hydrogen production via steam reforming of methanol using Cu/ZnO/Al2O3: Effect of catalyst synthesis method and Cu to Zn molar ratio on physico-chemical properties and catalytic performance

This research investigates the steam reforming of methanol (SRM) using Cu/ZnO/Al2O3 catalysts synthesized via three distinct methods: coprecipitation, hydrothermal, and sol-gel methods. A comprehensive analysis of the catalysts' physicochemical, morphological, and thermal properties was conducted, and their catalytic performances were compared. The coprecipitation method yielded catalysts with desirable catalytic properties, including high specific surface area, increased Cu0 area, increased Cu dispersion, and improved reducibility, leading to the highest catalytic performance compared to the other methods tested. These catalysts exhibited the highest methanol conversions of 91.5% and H2 yield of 90.9%, with a low CO selectivity of 0.61% at 280 °C. In contrast, catalysts synthesized via hydrothermal and sol-gel methods showed lower methanol conversions of 39.2% and 73.5%, H2 yields of 39.0% and 72.7%, and CO selectivity of 1.46% and 0.91%, respectively, at the same temperature. Further investigation of the coprecipitated catalysts involved varying the Cu/Zn molar ratios. The results revealed a noteworthy influence Cu/Zn ratio on the characterization results and catalytic performance. Notably, a Cu/ZnO/Al2O3 catalyst with a Cu to Zn ratio of 1 emerged as the optimal catalyst composition, demonstrating the highest catalytic performance for SRM.

Preferred crystal surface exposure and near-crystal surface desolvation construct efficient Zn plating/stripping reversibility

The Zn/electrolyte interface stability is related to HER, passivation, dendrites, corrosion and Zn2+ deposition orientation. Reducing the occupation of H2O dipoles in the inner layer of electrical double layer (EDL) is conducive to the inhibition of interfacial side reactions and directing the deposition of Zn2+ along the (002) crystalline surface, which are beneficial to the reduction of dendrites and the improvement of plating/stripping reversibility. A mechanism is elucidated by which Acetyl-L-carnitine Hydrochloride (A-L-CN) reconfigures the EDL structure and guides the selective deposition of Zn2+ in this paper. Theoretical calculations show that A-L-CN can cover the high-energy active sites on the Zn (101) crystal plane and control the specific crystal orientation of the deposits along the (002) crystal plane to produce faceted epitaxial growth. The electrochemical test results show that the Zn anode has excellent plating/stripping reversibility as well as good cumulative capacity (10 mA cm−2, 1 mA h cm−2, ACE of 99.80 %, CPC of 7,753 mA h cm−2). The assembled Zn2+ hybrid supercapacitor (ZHS) and Zn//PANI full cell show excellent performance (ZHS up to 60,000 cycles; the capacity retention ratio of Zn//PANI full cell is 76.7 % after 1,000 cycles). The work offers the possibility of achieving stabilized Zn/electrolyte interface performance.

Effect of Zn amount on AlZn-based composite material produced by high speed mechanical alloying method

Purpose The purpose of this study is AlZn-based produced by high speed mechanical alloying method to investigate the effect of Zn amount on the composite material, Al-Zn-Mg-Cu-SiC composite material billets are obtained by sintering. Design/methodology/approach Mechanical alloying, X-ray diffraction analysis (XRD) graphics, sintering, polishing, scanning electron microscopy and energy dispersive X-ray analyzer (EDX) images and micro hardness tests were applied, respectively. Findings In the XRD analysis results, it was observed that the Al peak height decreased as the alloying time increased. When the samples sintered for 90 min are examined, it can be clearly seen that the hardness increases as the Zn ratio increases. EDX analysis results also support XRD results. Originality/value Increase in strength will require the use of thinner sheet metal and smaller rivets to achieve the same strength. This will reduce the weight of the aircraft. Weight reduction also means less fuel consumption and more economical flight. This increase in strength is a very important scientific achievement.

Fe, Zn, and Mg stable isotope systematics of acapulcoite lodranite clan meteorites

AbstractThe processes of planetary accretion and differentiation, whereby an unsorted mass of primitive solar system material evolves into a body composed of a silicate mantle and metallic core, remain poorly understood. Mass‐dependent variations of the isotope ratios of non‐traditional stable isotope systems in meteorites are known to record events in the nebula and planetary evolution processes. Partial melting and melt separation, evaporation and condensation, diffusion, and thermal equilibration between minerals at the parent body (PB) scale can be recorded in the isotopic signatures of meteorites. In this context, the acapulcoite–lodranite meteorite clan (ALC), which represents the products of thermal metamorphism and low‐degree partial melting of a primitive asteroid, is an attractive target to study the processes of early planetary differentiation. Here, we present a comprehensive data set of mass‐dependent Fe, Zn, and Mg isotope ratio variations in bulk ALC species, their separated silicate and metal phases, and in handpicked mineral fractions. These non‐traditional stable isotope ratios are governed by mass‐dependent isotope fractionation and provide a state‐of‐the‐art perspective on the evolution of the ALC PB, which is complementary to interpretations based on the petrology, trace element composition, and isotope geochemistry of the ALC. None of the isotopic signatures of ALC species show convincing co‐variation with the oxygen isotope ratios, which are considered to record nebular processes occurring prior to the PB formation. Iron isotopic compositions of ALC metal and silicate phases broadly fall on the isotherms within the temperature ranges predicted by pyroxene thermometry. The isotope ratios of Mg in ALC meteorites and their silicate minerals are within the range of chondritic meteorites, with only accessory spinel group minerals having significantly different compositions. Overall, the Mg and Fe isotopic signatures of the ALC species analyzed are in line with their formation as products of high‐degree thermal metamorphism and low‐degree partial melting of primitive precursors. The δ66/64Zn values of the ALC meteorites demonstrate a range of ~3.5‰ and the Zn is overall isotopically heavier than in chondrites. The superchondritic Zn isotopic signatures have possibly resulted from evaporative Zn losses, as observed for other meteorite parent bodies. This is unlikely to be the result of PB differentiation processes, as the Zn isotope ratio data show no covariation with the proxies of partial melting, such as the mass fractions of the platinum group and rare earth elements.

Enhancing Optical Properties of Zn-Mn Solid Solution Hybrid Halides for Wide Color Gamut Backlight Displays.

Hybrid metal halides display a range of optical properties and hold promise for various applications such as solid-state lighting, anti-counterfeiting measures, backlight displays, and X-ray detection. The incorporation of zinc into (C13H26N)2MnBr4 aims to enhance its structural rigidity and improve its narrow band green light emission properties. The resulting (C13H26N)2ZnBr4 compound exhibits an identical crystal structure to (C13H26N)2MnBr4, indicating the potential for a solid solution of varying Zn and Mn ratios within this structural framework. (C13H26N)2Zn0.2Mn0.8Br4 exhibits significantly enhanced properties, including a photoluminescence quantum yield of 92%, a minimum full width at half maximum of 43nm, and 85% retention of room temperature emission at 420K. Additionally, crystals of (C13H26N)2ZnCl4 and (C7H18N)2ZnX4 (X = Br, I) are synthesized, with (C7H18N)2ZnBr4 displaying luminescent color changes dependent on excitation. (C7H18N)2Zn0.2Mn0.8Br4 demonstrates reversible phase transitions and alterations in optical properties. A white light-emitting diode utilizing (C13H26N)2Zn0.2Mn0.8Br4 and commercial phosphors exhibited a color gamut of 112.2% of the National Television Standards Committee 1931 Standard. This investigation introduces a stable and highly efficient narrow-band green phosphor suitable for displays.

Immobilization of heavy metals with chlorine and liquid phase formation during thermal treatment of MSWI fly ash

Due to effective detoxification, thermal treatment is a preferred treatment technology of municipal solid waste incineration (MSWI) fly ash. However, immobilization behavior of heavy metals during thermal treatment is unclear. In this work, a circulated fluidized bed fly ash with SiO2 addition and a grate furnace fly ash with high silica-aluminum coal ash addition were used to investigate combined effect of active chlorine content, liquid polymerization degree, temperature of initial liquid phase formation and liquid phase formation rate on the immobilization ratios of Zn, Pb and Cd by principle component analysis (PCA). The results show that the decrease in active chlorine content favors the immobilization of Zn, Pb and Cd because chlorination volatilization is reduced. Both the increase in liquid polymerization degree and the formation of initial liquid phase at low temperature promote the immobilization of Zn, Pb and Cd for physical encapsulation. However, a rapid formation of liquid phase is not favorable for the immobilization of Zn, Pb and Cd, because transfer of heavy metals between crystals and liquid phase is impeded by high viscosity of liquid phase during fusion. The results can provide a reference for how to achieve the immobilization of heavy metals by adjusting the chemical composition of MSWI fly ash during thermal treatment.

Synthesis, characterization, and performance evaluation of unsupported tetrametallic CoMoMnAl and CoMoZnAl catalysts for selective hydrodesulfurization (HDS)

New formulations of unsupported tetrametallic catalysts derived from layered double hydroxides (LDH) compounds were synthesized by a constant pH coprecipitation method, characterized, and evaluated in the selective hydrodesulfurization (HDS) of thiophene in the presence of cyclohexene. The layered double hydroxides were prepared using terephthalate (C8H8O2)2- as the interlayer anion with nominal aluminum molar fraction of 0.5, and nominal cobalt to MII (M = Zn or Mn) ratios of 0.2, 0.4 and 0.6. Molybdenum introduction in the LDH precursor was accomplished by an ion exchange process using the heptamolybdate anion. The calcined Mn samples showed a higher surface area than those obtained from Zn. The sulfidation was carried out in situ with a heating ramp up to 673 K and the catalysts were evaluated in a tubular flow reactor. The catalytic evaluation of Zn and Mn-based materials for simultaneous thiophene HDS and cyclohexene hydrogenation (HYD) was conducted at 573 K and 20 bar. The results show that the Zn-based unsupported catalysts synthesized here exhibited higher selectivity for the HDS reaction than an industrial one.

Synthesis and characterization of Zn-In-S composites for photocatalytic benzyl alcohol oxidation and nitrobenzene reduction

Photocatalytic transformation of organics is a promising alternative to conventional synthetic methodologies. ZnIn2S4 is active in photocatalytic redox reactions, but its performance is hindered by fast charge carrier recombination, and optimizing its properties through synthesis or modification is complicated. Herein, Zn-In-S based composites were prepared via a facile solvothermal method by varying the ratio of sulfide precursor (TAA) with a fixed Zn/ In molar ratio of 1: 2. The phase composition of the obtained materials depends on the amount of TAA. At lower ratios, composites consisting of crystalline In(OH)3 and unknown ZnxInySz phase were formed. Pure-phase ZnIn2S4 was obtained when the feed molar ratio of zinc and TAA was 1: 6 or higher. The photocatalytic oxidation of benzyl alcohol (BA) and reduction of nitrobenzene (NB) in a coupled system were applied to evaluate the activity of Zn-In-S-based composites. Under visible light irradiation, the ZnxInySz/ In(OH)3 composite (ZIS14) synthesized with a molar ratio of Zn to TAA of 1: 4 exhibited boosted and optimal performance compared to the bare ZnIn2S4 and other samples. After 5 hours of irradiation, the BA conversion and benzaldehyde (BAD) yield were 57 % and 55 %, respectively, and the NB conversion and aniline (AN) yield were 70 % and 35 %, individually, outperforming previous studies under similar experimental conditions. This work not only elucidates the photoredox process of BA and NB in one system, but also has significant implications for understanding the complex hydro/solvothermal processes involved in the fabrication of multicomponent sulfides.

Effect of Al doping on structural and optical properties of atomic layer deposited ZnO thin films

In this work, zinc oxide (ZnO) and aluminum-doped ZnO (AZO) thin films with varying Al contents were grown via atomic layer deposition on Si and glass substrates. The structural and optical properties of ZnO and AZO thin films were investigated using X-ray diffraction, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), photoluminescence (PL), and ultraviolet-visible spectroscopy. While undoped ZnO had a wurtzite crystal structure, Al2O3 layers altered the crystal structure depending on the Al content. With the increasing number of Al2O3 monolayers, the γ- Al2O3 structure became more prominent, and ZnO peaks were completely suppressed when the Zn ratio reached 10:1 and beyond. SEM images revealed that the thin films homogeneously covered the entire substrate surface. EDS mapping showed a uniform distribution of Zn, Al, and O in the structure. According to the XPS results, the thin films displayed significant peak intensities corresponding to the main components Zn, O, and Al. Zinc atoms were present only in their oxidized state, not as interstitial atoms. The O 1 s peak could be deconvoluted into three components: the oxygen-zinc bond, the oxygen-aluminum bond, and chemisorbed or OH species. In the AZO samples, a direct correlation was observed between the intensity of the Al 2p peak and the number of Al2O3 layers. Additionally, the calculated elemental ratio of Al increased from 2.582 to 23.955 at.% with more Al2O3 layers. Optical measurements revealed that ZnO and AZO thin films exhibit high transmittance in the visible region. Moreover, introducing Al2O3 layers into the supercycle led to an increasing trend in transmittance. Another improvement in the optical properties was observed as a blue shift in the absorption edge with Al doping, indicating band gap widening. The optical band gap of the ZnO thin films increased from 3.2 to 3.5 eV with Al doping. The origin and concentration of defects were evaluated by deconvoluting the PL spectra. A comparative investigation of the PL spectrum and XPS results revealed variations in defect concentration with deposition parameters and defect formation mechanism was discussed.

Modulating N doping in cobalt-derived catalyst from zeolitic imidazolate frameworks for high performance zinc-air batteries

In this work, the N-content was varied using ammonium hydroxide (A), urea (U), and melamine (M) impregnated in a zeolitic imidazolate framework (ZIF-67) with a Co to Zn ratio of 7:93. The N-doped ZIF-derived carbon materials and the reference ZIF Co 7:93 underwent pyrolysis under identical conditions, yielding C-ZIF, CA-ZIF, CU-ZIF, and CM-ZIF. Different nitrogen sources mainly affected the surface area and graphitic-N content, yielding up to three times the N-content of the reference. All materials presented ORR onset potentials near 0.9 V and E10mA cm−2 near 1.6 V for the OER. However, CM-ZIF enabled rechargeability at different current densities, with a round-trip efficiency of 68.8 % at 5 mA cm−2, decreasing only to 54 % at 15 mA cm−2.

Crystallinity-Driven Formation of Highly Arrayed ZnO Nanorods Via Low-Temperature Chemical Bath Deposition on Transparent Conductive Oxide Substrates

The wide-band gap semiconductor zinc oxide (ZnO) nanostructures have attracted much interest in extensive applications such as gas sensors, photoelectrodes in dye sensitized solar cells and catalysts, etc. Among the various synthesis methods of ZnO nanostructures, chemical bath deposition (CBD) method is a low cost and simple technique to synthesize nanostructures. However, there are still remaining issues on growth of well- arrayed ZnO nanostructures with high uniformity and high crystallinity. In this research, we conducted a comprehensive investigation into various parameters, including seed layers, seed-layer thickness, precursor concentration, and reaction time during CBD process. Three kinds of transparent conductive oxide (TCO) films, specifically AZO, GZO, and ITO films, each with a thickness of 300nm, were individually deposited on glass substrates using radio frequency magnetron sputtering and DC magnetron sputtering. These obtained TCO films served as seed layers for the fabrication of ZnO nanorods in CBD process. The solution was prepared with Zn(NO3)2•6H2O and hexathylenetetramine (HMTA) diluted into deionized water, which was heated to 95 °C during CBD process. As the results: 1) Effect of different seed layers: ZnO nanorods exhibited vertically aligned hexagonal structures with uniform morphology when grown on AZO and GZO thin films. The alignment was found to depend on the crystal growth direction of the underlying TCO seed layers. Higher crystallinity of the seed layer contributed to superior alignment, with the crystal mismatch ratio between ZnO nanorods and GZO/AZO films being significantly lower than that with ITO film. 2) The thickness effect investigation was using AZO films varied from 100nm to 300nm. It was found that the thickness influenced the morphology of ZnO nanorods, correlating with the grain sizes of the seed layer thin films. Increasing film thickness led to larger average grain sizes, contributing to the diameter increase of ZnO nanorods in the CBD process, resulting in the improvement of crystallinity of ZnO nanorods. 3) The precursor ratio between concentration ratio of Zn(NO3)2•6H2O and HMTA was set as 2:0.25, 2:0.5, 2:1 and 2:2 individually for ZnO nanorods growth on AZO film. Increasing HMTA concentration initially led to an increase in diameter and length of ZnO nanorods, followed by a decrease at higher ratio of 2:2. The highest crystallinity of ZnO nanorods was obtained at the optimized ratio at 2:1. 4) The growth reaction time was investigated on ZnO nanorods grown on AZO film with concentration ratio of Zn(NO3)2•6H2O and HMTA at 2:1 with varied reacting time from 1 to 5 hours in CBD process. It was found that the reaction time significantly influenced on the growth and crystallinity of well-aligned ZnO nanorods on the as-deposited AZO seed layer. The crystallinity of ZnO nanorods in (0001) growth orientation was improved when the reaction time was increased from 1 hour to 5 hours during the CBD growth. The highest crystallinity was obtained from the ZnO nanorods grown with 5 hours reaction time. When the growth reaction time was increased, more Zn2+ ions were generated and strongly bonded with oxygen. The formed ZnO could be stacked along the c-axis (0001) growth direction and resulted in the length increasing during the CBD process. All fabricated ZnO nanorods showed a high transmittance of over 70% in the visible region. The ZnO nanorods synthesized on AZO substrates with optimized fabrication conditions will be in high potential for optoelectronic applications.

Unlocking Co3O4–ZnO p-n heterojunction for superior acetone gas sensing detection

In this study, we synthesized pure ZnO and Co3O4–ZnO precursors with varied Co, Zn ratios via solvothermal method, and then the precursors were calcined at 400 ​°C for 2 ​h in a muffle furnace under air to obtain composites for acetone detection. The structure, morphology, elemental composition, microstructure and chemical state of these materials were systematically studied by various characterization techniques. Additionally, we also evaluated the gas sensing performance of the composites-based sensors, focusing on optimal operating temperature, baseline resistance, repeatability, stability, selectivity, response/recovery time, and resistance under varying relative humidity. The findings reveal that 3 ​% Co3O4–ZnO-based sensor exhibit the highest response value to 100 ​ppm acetone (74), showing an enhancement of approximately 9.3 times compared to the pure ZnO-based sensor (8). Furthermore, the 3 ​% Co3O4–ZnO-based sensor demonstrate the advantages of rapid response/recovery times (15 ​s/2 ​s), outstanding selectivity, and remarkable stability. The gas sensing mechanism of the composite material is also discussed in detail, which provides insights into the observed enhancement of gas sensing performance. It provides an idea for the follow-up study on gas sensing performance of acetone sensors.

ZnO/TiO2 photocatalytic nanocomposite for dye and bacteria removal in wastewater

This study investigates ZnO/TiO2 nanocomposites synthesized by the sol–gel method for their potential application in textile wastewater treatment. The physicochemical properties of these materials were comprehensively characterized using various analytical techniques, including transmission electron microscopy (TEM), x-ray diffraction (XRD) analysis, x-ray fluorescence (XRF) spectroscopy, Brunauer–Emmett–Teller (BET) surface area analysis, and UV–visible (UV-Vis) spectroscopy. XRD and XRF analyses confirmed the formation of a ZnO/TiO2 heterostructure. TEM images revealed a quasi-spherical morphology with slight agglomeration. The ZnO/TiO2 nanocomposite with a 1:5 molar ratio of Zn(II):Ti(IV) showed the highest BET surface area (91.345 m2 g−1) and the narrowest band gap (Eg = 3.06 eV). This composite demonstrated efficient degradation of methylene blue dye under sunlight irradiation and exhibited 100% antibacterial activity against S. typhi and S. aureus at concentrations ≥5 mg ml−1, indicating its potential for treating textile wastewater.