Sol-gel Deposition Research Articles

Polarization Reduction of a Novel Cell Configuration Based on Thin-Film Electrolyte on Porous Oxide Framework for Solid State Batteries Application

In early 1990s, rechargeable Li batteries using inorganic ionic conductors as solid electrolytes have been proposed. Because of their improved safety features, solid state batteries have received great attention recently. Although using Li metal as an ideal high-capacity anode has been a long-term goal, the critical issues remaining to be solved are the polarization contributed from the solid electrolyte and the electrode/electrolyte interface. Thus, to form a Li-conducting thin film with good adhesion with an adequate conducting and porous oxide framework in between Li anode and thin electrolyte may be a solution for the reduction of above-mentioned polarization observed in the solid state batteries. Thus, the main objective of this study is to (i) calculate/estimate the polarization reduction in a solid state cell using thin-film inorganic electrolyte and metallic Li as anode, (ii) to complete the experimental design for in-situ formation of thin electrolyte based on sol-gel deposition of an oxides precursor on a porous and conducting oxide framework followed by heat-treatment at temperatures > 700°C. The verification of polarization reduction contributed from the proposed thin-film electrolyte as well as the porous/conducting framework will be carried out in the near future.

Sol–Gel Synthesis of ZnO:Li Thin Films: Impact of Annealing on Structural and Optical Properties

A sol–gel deposition approach was applied for obtaining nanostructured Li-doped ZnO thin films. ZnO:Li films were successfully spin-coated on quartz and silicon substrates. The evolution of their structural, vibrational, and optical properties with annealing temperature (300–600 °C) was studied by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), UV-VIS spectroscopic, and field emission scanning electron microscopic (FESEM) characterization techniques. It was found that lithium doping maintains the wurtzite arrangement of ZnO, with increasing crystallite sizes when increasing the annealing temperature. Analysis of the FTIR spectra revealed a broad main absorption band (around 404 cm−1) for Li-doped films, implying the inclusion of Li into the ZnO lattice. The ZnO:Li films were transparent, with slightly decreased transmittance after the use of higher annealing temperatures. The porous network of undoped ZnO films was transformed to a denser, grained, packed structure, induced by lithium doping.

Facile fabrication of Au/SiO2 nanostructures from 1D to 3D nanotubes networks using templating methods

We report a facile fabrication method for free-standing gold (Au) or silica (SiO2) nanotubes with highly controlled geometry and ordered porosity (pNTs) and their nanostructuration from 1D to 3D interconnected networks. A dual nano-templating method was employed using polycarbonate membranes as first mold for the nanotubes, together with stacked polystyrene (PS) nanospheres to induce porosity. The pore size in the final nanotube walls can be controlled by adjusting the ratio x (where x = internal diameter of the nanotube divided by the diameter of the nanospheres), which determines the packing order of the spheres in the tubes. Then, gold electroless or silica sol-gel deposition were performed in the dual-templated structure to obtain Au or SiO2 pNTs, respectively. The templates removal was performed in one step using dichloromethane. A further functionalization of the silica pNTs with Au NPs using the electroless deposition method was successfully implemented as well, leading to a homogeneous dispersion of Au NPs with a size of 11 ± 2.8 nm. Chemical compositions and optical properties of the so-obtained materials were determined by XPS and UV–visible analyses, respectively.

Silane-modified bentonite clay-coated membrane development on ceramic support for oil/water emulsion separation using tuning of hydrophobicity

Bentonite clay-coated and silane-modified hydrophobic composite membranes were prepared on the ceramic support by facile sol-gel deposition route to effectively separate various oil-water colloidal solutions. This study explores the correlation of silane content involved in optimizing and modifying surface hydrophobicity, membrane pore characteristics, and the solvent permeation properties in terms of oil permeation rate and water rejection (%) in oil-water emulsion solutions. Membrane surface modifications with relatively higher silane content (∼15%) reduced the membrane pores extensively, increasing the water rejection properties but the oil flux was reduced modestly. The oil flux increases with the introduction of reduced silane content (∼2%) but the water rejection properties were compromised. Silane: solvent ratio of 1:100 (silane loading ∼10%) proved to be efficient for the separation (94–99%) of various hydrocarbons such as hexane, toluene, cyclohexane, and heptane from emulsified solutions with permeate flux of 25–40 Lm−2h−1. Cake filtration model was found suitable to explain the membrane fouling. The optimized membrane also recorded a minimal loss of hydrophobicity and mechanical strength enduring oil atmosphere and corrosive environments. The overall study supported by suitable physicochemical material characterizing techniques reveals that optimizing silane concentration in bentonite-based clay composite membrane surface modification can be an effective oil/water separation strategy.

Modern Smart Street Light Monitoring Systems

Abstract: This study highlights the importance of Modern Street light control systems over traditional ones, with LED lamps emerging as the most suitable choice due to their advantagessuch as reduced heat production, lower electricity consumption, and extended lifespan. The main goal is to enhance system efficiency by minimizing unnecessary electricity loss during daylight and when lighting is not required. Automating street lights using LDR and PIR sensorsin conjunction with Arduino Uno offers a costeffective and secure solution, eliminating the drawbacks of manual switching and simplifying cost reduction and maintenance. Additionally,applying a ZnO coating to the street light casings provides effective protection against dust and moisture, resulting in efficient lighting. The process involves sol-gel deposition of ZnO nanoparticles on silica glass substrates, followed by preannealing and repeated dip coating. Annealing at temperatures between 450°C and 600°C further improves the results. The uniformand defect-free coatings are confirmed by SEM images, while transmission spectra reveal over80% penetration of visible light (400 nm to 900 nm). Lower precursor concentrations lead to better penetration of light below 300 nm wavelength.

Tailoring of the Structural, Optical, and Electrical Characteristics of Sol-Gel-Derived Magnesium-Zinc-Oxide Wide-Bandgap Semiconductor Thin Films via Gallium Doping.

The Ga-doped Mg0.2Zn0.8O (GMZO) transparent semiconductor thin films were prepared using the sol-gel and spin-coating deposition technique. Changes in the microstructural features, optical parameters, and electrical characteristics of sol-gel-synthesized Mg0.2Zn0.8O (MZO) thin films affected by the amount of Ga dopants (0-5 at%) were studied. The results of grazing incidence X-ray diffraction (GIXRD) examination showed that all as-prepared MZO-based thin films had a wurtzite-type structure and hexagonal phase, and the incorporation of Ga ions into the MZO nanocrystals refined the microstructure and reduced the average crystallite size and flatness of surface roughness. Each glass/oxide thin film sample exhibited a higher average transmittance than 91.5% and a lower average reflectance than 9.1% in the visible range spectrum. Experimental results revealed that the optical bandgap energy of the GMZO thin films was slightly higher than that of the MZO thin film; the Urbach energy became wider with increasing Ga doping level. It was found that the 2 at% and 3 at% Ga-doped MZO thin films had better electrical properties than the undoped and 5 at% Ga-doped MZO thin films.

Rational fabrication of Ti0.69Zr0.31O2 modified Au-loaded halloysite core-shell catalyst for highly efficient reduction of 4-nitrophenol and dye pollutants

Catalytic reduction method can reductively degrade some highly toxic and harmful pollutants and transform them into useful chemical resources with low toxicity and easy biodegradability, owning the advantages of environmental friendliness, economic effectiveness and mild conditions. This study reported the rational fabrication of the HNTs-Au@Ti0.69Zr0.31O2 hollow tubular core-shell catalyst for facile reductive degradation of aqueous 4-nitrophenol and azo dye pollutants. The catalyst employed the interfacial reaction strategy for aminopropyl-functionalization of halloysite nanotubes as core, amino electrostatic adsorption and in situ redction of ultrasmall Au nanoparticles with good dispersibility, and sol-gel deposition of Ti0.69Zr0.31O2 shell. The obtained HNTs-Au@Ti0.69Zr0.31O2 catalyst manifested superior catalytic performance and atom utilization efficiency of Au active sites for reduction of 4-nitrophenol, methylene blue and methyl orange in comparison to those control samples. The integration of TiO2 and ZrO2 within Ti0.69Zr0.31O2 shell enriched the porosity of the catalyst, and generated the extraordinary interfacial chemical effect on Au NPs with improved surface electronic state. The interlayer-embedded Au nanoparticles were effectively solidified and avoided from agglomeration and loss, where the reactive electron migration rate from BH4- to target pollutants upon Au surfaces was elevated for prominent catalytic reaction rate. The unique structural characteristics and synergistic enhancement effect of catalyst components created excess catalytic active sites at the hybrid interface surrounded Au nanoparticles due to the strong metal-carrier chemical effect, and contributed to the construction of the high-performance catalytic system, which endowed the HNTs-Au@Ti0.69Zr0.31O2 catalyst with remarkable catalytic capability, reusability and structural stability. The reaction mechanism and structure-property relationship were finally proposed.

Layered Sol-Gel Deposition of a Sn, Ti, Zn, and Pr Mixed Oxide Thin Film with Electrical Properties for Gas Sensing.

This article presents a layered mixed oxide thin film composed of Sn, Ti, Zn, and Pr obtained by sol-gel deposition for gas sensing applications. The film was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV-Vis spectroscopy, Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), and Electrochemical impedance spectroscopy (EIS). X-ray diffraction results showed the presence of a single crystalline phase with a cassiterite-like structure. Raman spectroscopy revealed characteristic bands of oxygen-deficient SnO2-based nanocrystallites. The band gap energy calculated from UV-Vis spectroscopy is Eg = 3.83 eV. The XPS proved the presence on the surface of all elements introduced by the inorganic precursors as well as their oxidation states. Thus, Sn4+, Ti4+, Zn2+, and Pr3+ were detected on the surface. Moreover, by XPS, we highlighted the presence of OH groups and water adsorbed on the surface. SEM showed the five-layer morphology of the film after five successive depositions. Electrochemical properties were determined by EIS-impedance spectroscopy. The selectivity for gas sensing was also investigated for methane, propane, and formaldehyde and the gas sensing mechanism was explained. The results indicated that the mixed oxide thin film exhibited high sensitivity and selectivity towards specific gases.

High Quality Factor in Solution-Processed Inorganic Microcavities Embedding CsPbBr3 Perovskite Nanocrystals.

Optical microcavities grant manipulation over light-matter interactions and light propagation, enabling the fabrication of foundational optical and optoelectronic components. However, the materials used for high-performing systems, mostly bulk inorganics, are typically costly, and their processing is hardly scalable. In this work, we present an alternative way to fabricate planar optical resonators via solely solution processing while approaching the performances of conventional systems. Here, we couple fully solution-processed high dielectric contrast inorganic Bragg mirrors obtained by sol-gel deposition with the remarkable photoluminescence properties of CsPbBr3 perovskite nanocrystals. The approach yields microcavities with a quality factor of ∼220, which is a record value for solution-processed inorganic structures, and a strong emission redistribution resulting in a 3-fold directional intensity enhancement.

Sol–gel deposition of Al-doped ZnO thin films: effect of additional zinc supply

Sol–gel deposition of Al-doped ZnO thin films: effect of additional zinc supply

UV–Vis activated CuO/CuS/WO3@PANI heterostructure for photocatalytic removal of pharmaceutical active compounds

The sol-gel and spray deposition were employed to develop a complex heterostructure based on CuO/CuS/WO3@PANI able to use both UV and Vis light in order to generate charge carriers required in the photocatalytic applications. The sol-gel was used to develop the CuO/CuS/WO3 heterostructure in a three-step method where the components act as nucleation sites. The samples crystallinity and morphology were characterized indicating that all components exhibit crystalline structure and the morphology change with the addition of each component. Adding PANI during the film development have doubled the sample specific surface (51.8 m2/g for CuO/CuS/WO3 vs 94.3 m2/g for CuO/CuS/WO3@PANI) and have increased the layer density (3.43 g/cm3 vs. 4.26 g/cm3). Photocatalytic activity was evaluated for pharmaceutical active compounds removal in the presence of both UV and Vis light. The results indicate that CuO/CuS/WO3@PANI exhibit highest mineralization efficiencies of 75.5% toward penicillin G and 78% toward amoxicillin (50 ppm initial concentration). The mechanism of charge generation indicates that the heterostructure components have a synergic action contributing to the redox potential required to form the (super)oxidative species.

Coating materials and processes for cathodes in sulfide-based all solid-state batteries

This short review focuses on critical issues of cathode–solid electrolyte (SE) interface, including chemical instability, space-charge layer, and mechanical failure for all solid-state batteries (SSBs). Moreover, we reviewed recent R&D efforts to solve the issues by passivating the cathode interfaces using various materials (e.g. metallic oxides, carbonates, phosphates, halides, and polymers) and coating processes (e.g. sol-gel, dry coating, and atomic layer deposition). Finally, future perspectives have been outlined to understand fundamental electro-chemo-mechanical reactions occurring through coating layers to improve the performances of SSBs in the future.

Processing and Weathering of Sol-Gel Clearcoats for Coil-Coated Steel

Clearcoats provide long-term aesthetics and protection for underlying coating systems, increasing product lifetimes. However, organic clearcoats are predominantly produced using fossil-fuel feedstocks. In search of a sustainable alternative, an experimental investigation was conducted on the development of glass-like clearcoats produced using the sol-gel process. The processing of sol-gel clearcoats over a pigmented polyurethane coating was studied by modifying the sol-gel solution pH, ageing, curing, precursor chemistry and deposition techniques. Under optimal formulation and processing conditions, defect-free sol-gel clearcoats were produced that have the potential to be scaled up to a coil-coating line using existing technologies. Mechanical testing demonstrated the coatings had excellent adhesion, hardness, and flexibility. Furthermore, accelerated laboratory weathering tests revealed the sol-gel coatings had superior degradation resistance compared to the organic coatings tested, resulting in negligible colour changes and higher gloss retention after 4000 h of exposure. The durability and environmental benefits of sol-gel clearcoats highlight their potential as a replacement for traditional organic clearcoats in a variety of applications.

Designing Highly Photoactive Hybrid Aerogels for In-Flow Photocatalytic Contaminant Removal Using Silica-Coated Bacterial Nanocellulose Supports.

This study explores the use of silica-coated bacterial nanocellulose (BC) scaffolds with bulk macroscopic yet nanometric internal pores/structures as functional supports for high surface area titania aerogel photocatalysts to design flexible, self-standing, porous, and recyclable BC@SiO2-TiO2 hybrid organic-inorganic aerogel membranes for effective in-flow photo-assisted removal of organic pollutants. The hybrid aerogels were prepared by sequential sol-gel deposition of the SiO2 layer over BC, followed by coating of the resulting BC@SiO2 membranes with a porous titania aerogel overlayer of high surface area using epoxide-driven gelation, hydrothermal crystallization, and subsequent supercritical drying. The silica interlayer between the nanocellulose biopolymer scaffold and the titania photocatalyst was found to greatly influence the structure and composition, particularly the TiO2 loading, of the prepared hybrid aerogel membranes, allowing the development of photochemically stable aerogel materials with increased surface area/pore volume and higher photocatalytic activity. The optimized BC@SiO2-TiO2 hybrid aerogel showed up to 12 times faster in-flow photocatalytic removal of methylene blue dye from aqueous solution in comparison with bare BC/TiO2 aerogels and outperformed most of the supported-titania materials reported earlier. Moreover, the developed hybrid aerogels were successfully employed to remove sertraline drug, a model emergent contaminant, from aqueous solution, thus further demonstrating their potential for water purification.

Resistive switching performance and synaptic behavior of La-doped HfO2 thin film

Resistive random-access memory has great application prospects in developing nonvolatile memory and artificial synapse devices. In this work, lanthanum (La) doped hafnium dioxide (HfO2) (La: HfO2) thin film is fabricated by sol-gel deposition. Using gold (Au) and lanthanum nickelate (LaNiO3) as electrodes, the resistive switching performance and synaptic behavior of memristor based on La: HfO2 thin films with different doping concentrations as resistive switching layers are investigated. Current-voltage characteristics show that La-doped devices all exhibit bipolar resistive switching performance. When La doping concentration is 10%, the device shows reliable switching ratio (∼103) under 110 consecutive cycles. And the conduction mechanism of the device in high resistance state and low resistance state is analyzed by ohmic conduction and space charge limited conduction. In addition, the analog resistive switching can be obtained by increasing the voltage scanning and the result reveals that the device can be used to mimic the potentiation and depression behavior of biological synapses. Au/10% La: HfO2/LaNiO3/Si memristor effectively simulates the synaptic properties, such as long-term potentiation/depression, short-term potentiation/depression, paired-pulse facilitation and spike-time-dependent-plasticity learning rule. Furthermore, the information is classified and processed in an 8×8 pixel array. These findings will open up a unique way for the future development of nonvolatile memory and neural morphology computation.

A Hybrid Approach to Surface Engineering Based on Laser Texturing and Coating

A hybrid approach based on laser texturing and surface coating for the combined modification of surface topography and chemistry has been proposed to provide a versatile approach for the development of functional surfaces. The experimental procedure comprised nanosecond pulsed laser texturing of AISI 304 stainless steel substrates followed by the deposition of thin (<1 µm) coatings with two different technologies, sol–gel deposition and PE-CVD, with the aim of independently modifying the surface topography and chemical composition. Laser texturing with different scanning strategies achieved a variety of surface morphologies with an arithmetic mean height (Sa) in the range 0.2–6.4 µm. Coatings were then deposited on laser-textured substrates to quantify the deposition effectiveness and the influence of the coating type and parameters on the resulting surface topography and chemistry. Sol–gel deposition was found to be more effective with a polymeric interlayer, improving adhesion between the coating and the textured surface; however, this also led to an increase in Sa of approximately 0.5 µm. Conversely, PE-CVD was effective in modifying the surface chemistry while inducing no measurable differences in surface morphology, effectively decoupling the texturing and coating processes. Analysis of the surface chemistry showed a higher concentration of silicon for PE-CVD than sol–gel deposition and therefore a more pronounced effect on the surface chemical composition.

Enhanced resistive switching performance of spinel MnCo2O4 resistive random access memory devices: Effects of annealing temperatures and annealing atmospheres

The spinel MnCo2O4 (MCO) thin films were fabricated on Pt/Ti/SiO2/Si substrates for resistive memories via sol-gel spin-coating deposition method under different annealing temperatures and annealing atmospheres. The 650oC-annealing Pt/MCO/Pt device shows better bipolar resistance switching parameters than the devices annealed at 600 °C and 700 °C. The nitrogen-annealing Pt/MCO/Pt device exhibits optimum resistance switching parameters due to increasing of the oxygen-vacancies proportion, formation of confined and stable conductive filaments, and suppressing of the randomness of oxygen vacancies. The carrier transportation mechanisms of the devices with numerous oxygen-vacancies content in low resistance state (LRS) and high resistance state (HRS) are dominated by Ohmic conduction and Schottky emission, respectively. For the devices with fewer oxygen-vacancies content, the conduction mechanisms at LRS and HRS can be described by nearest-neighboring hopping conduction and space-charge-limited current model, respectively. This work indicates that the spinel MCO films have good potential application in resistive random access memory.

The effect of temperature and distance of hot airflow on the quality of MAPbCl3 thin films grown by sol–gel deposition

The effect of temperature and distance of hot airflow on the quality of MAPbCl3 thin films grown by sol–gel deposition

Polymeric solar cell with 18.06% efficiency based on poly(para-nitroaniline)/TiO2 composites

In this paper, the poly para-nitro aniline [PPNN]/titanium (IV) oxide [TiO2]NPs composite was synthesized and investigated followed by the fabrication of thin film. The sol gel and physical vapor deposition (PVD) techniques have been successfully used to deposit [PPNN/TiO2]MNC thin film with good adhesion and film thickness ≅ 100 ± 3 nm. The structural and morphological properties of [PPNN/TiO2]MNC thin films were studied by X-ray diffraction (XRD) and scanning electron microscope (SEM). The measured optical properties of [PPNN/TiO2]MNC thin films as Reflectance (R) in the UV–vis–NIR spectrum, Absorbance (Abs), and Transmittance (T) have been employed to probe the optical characteristics at room temperatures. As well as the calculations of TD-DFT (time-dependent density functional theory) and the optimization through TD-DFT/Mol3 and Cambridge Serial Total Energy Bundle (TD-FDT/CASTEP) were employed to study the geometrical characteristics. The rectifier ration (RR), indeality factor (n) and barrier potential ΦB (eV) values are 0.74 × 105, 2.98 and 1.05 at 375 K, respectively. The Au/[PPNN/TiO2]MNC/p-Si/Al heterojunction device's power conversion efficiency are 18.06 at 200 W. cm−2. The obtained results candidates [PPNN/TiO2]MNC thin film as a good material for solar cells and optoelectronic devices.

Tuning Au/SiO2 nanostructures from 1D to 3D interconnected nanotube networks using polycarbonate porous templates.

We report a simple process, based on the combination of sol-gel deposition and nano-templating with polycarbonate membranes, for the synthesis of 1D to 3D free-standing silica (SiO2) interconnected nanotube (NT) networks. The thickness and porosity of the SiO2 nanotube walls can be, respectively, controlled by adjusting the ethanol amount in the sol-gel reaction mixture and by the addition or not of a porogen agent during the synthesis. Internal functionalization of 1D and 3D porous and non-porous SiO2 NTs by Au nanoparticles (NPs) was then performed using electroless deposition leading to particle sizes ranging from 15 to 20 nm. Characterization of all these systems by SEM-EDX, TEM, ICP and XPS clearly demonstrated the impact of the porosity of SiO2 on the amount and localization of Au NPs. Selective functionalization of the inner or the inner + outer surfaces of SiO2 NTs was achieved by keeping or freeing the SiO2 NTs from the template prior to electroless deposition, respectively. Moreover, UV-visible analysis confirmed plasmon resonance associated with Au NPs in all functionalized systems, paving the way to applications in many fields such as nano-medicine or (photo-)catalysis. In particular, the free-standing interconnected silica-based nanotube systems provide unique features of great interest for use in nanoscale fluidic bioseparation, sensing, and flow (photo)-catalytic chemistry, as demonstrated herein for the photodegradation of methylene blue.