Dip-coating Technique Research Articles

Implementation of an Automated Film Deposition Equipment under the sol/gel Dip-Coating Technique

We present the design, construction, and implementation of thin film deposition equipment based on the Sol/Gel dip-coating technique for the fabrication of coatings under controlled deposition conditions and working environment at ambient temperature and pressure. The deposition system includes a 304 stainless steel structure and a moving platform that holds the substrate and is transported along vertical axes at a deposition distance of up to 30 cm in height. The mechanical and electronic design was considered, using computer-aided development and dimensional validation (for the structure and the motion transmission system) and the programming of the system using the Arduino platform. The design focused on the deposition speed control for the functional equipment operations, whose operating principle is based on a PWM scheme, achieving an immersion/extraction speed parameter in ranges between 1.5 cm/s and 3.5 cm/s (with a resolution of ± 0.2 cm/s). The operation of the equipment and the reproducibility of the deposits were tested by studying the optical properties of CuCoMn coatings on glass. A substrate immersion/extraction speed of 1.5 cm/s and precursor agitation time (0.83 h - 0.98 h) were used, obtaining absorbances higher than 90%. In conclusion, the implemented prototype will allow the research group to produce reproducible thin films of better quality than those made manually, which can be produced at a low cost and offer the possibility of sustainable maintenance of the equipment.

Durable and covalently attached antibacterial coating based on post-crosslinked maleic anhydride copolymer with long-lasting performance

Clinical application of silicone rubber often encounters challenges. Here a strategy of free radical polymerization with 2-ethylhexyl acrylate (2-EHA) and maleic anhydride (MAh) to introduce durable crosslinked antimicrobial coating that covalently attached on silicone rubber substrate. The 2-EHA and MAh component endow the copolymer with good flexibility and further functionalization respectively. The copolymer coating is covalently bonded to the amine functionalized silicone rubber surface using a simple dip-coating technique and the thickness is adjustable. Poly (hexamethylene biguanide) (PHMB) is covalently coupled on the coating under mild conditions, and the immobilization density of PHMB is up to 3 mg cm−2. The coating layer crosslinked by 1,4-butanediamine gas to enhance the durability of the coating and inhibit undesired swelling and remains intact after 500 bending cycles. The modified substrate exhibits excellent antibacterial activity, with 99.9 % and 95.1 % inhibition rate towards S. aureus and E. coli, respectively. It still maintained 96.2 % of inhibition activity even after 12-day-long culturing with bacteria in simulated urine environment, exhibiting excellent long-term antibacterial stability. The results show that a simple, universal and scalable method to introduce antibacterial properties on polymer substrates, which also provides a new idea for the preparation of flexible cross-linking layers.

Structural characteristics and opto-electrical properties of in-situ synthesized polyaniline films

In the present study, polyaniline (PAni) thin films have been deposited on glass substrates by in-situ chemical polymerization method using simple dip-coating technique and their opto-electrical properties have been studied. The structure of deposited films have been analysed with Fourier transform infrared (FTIR) and Raman spectroscopic techniques to investigate the effect of deposition times on the conjugation length, polaron/bipolaron concentrations and other molecular structure conformations. FTIR and Raman spectroscopy studies reveal increase in both the conjugation length and the polaron/bipolaron carrier concentration with increasing deposition time of the prepared PAni films. The optical properties and optical band-gap of the deposited films have been estimated through UV–visible spectroscopy. The optical band-gap of the deposited films has been found to decrease from 3.31 eV to 3.13 eV with increase in deposition time from 1.5 h to 2.5 h, and further it has been increased slightly to 3.19 eV for the PAni film deposited for 3 h. The electrical conductivity of the deposited films has been found to increase with decrease in optical band gap. The parameters estimated from FTIR, Raman, UV–visible spectroscopy and electrical measurements are in good agreement with each other. It has been observed that the optical and electrical properties of the deposited films depend on the conjugation length of PAni. The polymerization time of 2.5 h has been found to be optimum for obtaining PAni thin films with good electrical conductivity and low optical band gap.

Corrosion resistance improvement of the Ti6Al4V/UHMWPE systems by the assembly of ODPA molecules by dip coating technique

Living with degenerative diseases, such as arthritis and osteoporosis, is challenging if orthopedic devices manifest adverse effects caused by corrosion processes. Ti6Al4V alloy is used to manufacture orthopedic implants due to its excellent mechanical and osseointegration properties. Nonetheless, it has poor resistance to wear and corrosion by biological fluids and mechanical activity. This degradation process generates the need to improve the corrosion resistance of metallic biomaterials used as biomedical implants. Dip-coating technique is a wet coating method used to lessen wear damage on the metal surface and can produce coatings using a wide variety of molecules at a low cost. In this work, Ti6Al4V alloys were coated with ultra-high molecular weight polyethylene (UHMWPE) and Octadecylphosphonic Acid (ODPA) films forming a UHMWPE/ODPA bilayer coating by dip-coating method to improve protection efficiency against corrosion in phosphate-buffered isotonic saline solutions and proposed it as alternative coatings to delay the failure of medical implants. The optimization of individual coated systems were obtained with an immersion time of 40 s (Ti6Al4V/UHMWPE) and 30 h (Ti6Al4V/ODPA) with corrosion current densities of 1.51 × 10−9 A cm−2 and 6.8 × 10−8 A cm−2, respectively. The formation of bilayer coatings reduces the average roughness from 19.34 nm (Ti6Al4V/UHMWPE) to 12.67 nm (Ti6Al4V/UHMWPE/ODPA). ODPA deposition on UHMWPE films changes the corrosion rate by interfering with the anodic and cathodic reactions, reducing the corrosion rate to 7.46 × 10−4 μm y−1 and an estimated corrosion protection efficiency of about 99.99 %. The results show a superior performance as a protective barrier over the individual films (1.19 μm y−1 with 97.2 %, and 0.026 μm y−1 with 99.9 %, ODPA, and UHMWPE, respectively), improving the corrosion resistance of the Ti6Al4V alloys.

Study on the role of rGO in enhancing the electrochromic performance of WO3 film

In the present work, an improved electrochromic thin film has been developed with faster color switching time on incorporation of rGO in WO3 film. Here, pristine WO3 and rGO-WO3 (rGO concentration varying from 1–7wt%) based nanocomposite electrochromic films were fabricated on ITO coated glass substrate, by utilizing a facile sol-gel dip-coating technique. Detailed structural and morphological analyses of the films were carried out using XRD, FESEM, TEM and Raman Spectroscopy. Assimilating the electrochromic properties of all the films showed that, 5wt% rGO incorporated WO3 film gave a maximized electrochemical performance with minimum degradation in optical transmittance. The film also exhibited an optical modulation of ∼ 50% and a better switching response having coloration time (tc) ~ 5.3 s and bleaching time (tb) ~ 6.2 s as compared to the pristine film (tc~ 9.6 s, tb ~ 10.4 s). Incorporation of rGO also resulted in an enhancement of coloration efficiency from ∼ 81 to ∼ 386 cm2/C. The Electrochemical Impedance Spectroscopy (EIS) analysis of pristine and rGO loaded film clearly revealed better charge transfer on incorporation of rGO. The cyclic stability study exhibited ∼ 25% deterioration in optical transparency of the bare WO3 film which was < 10% for the rGO impregnated film. An ex-situ XRD analysis demonstrated that a crystal dislocation occurring in pristine WO3 sample was responsible for the same.

Al2O3-Based Hollow Fiber Membranes Functionalized by Nitrogen-Doped Titanium Dioxide for Photocatalytic Degradation of Ammonia Gas.

In recent years, reactive ammonia (NH3) has emerged as a major source of indoor air pollution. In this study, Al2O3-based hollow fiber membranes functionalized with nitrogen-doped titanium dioxide were produced and successfully applied for efficient heterogeneous photocatalytic NH3 gas degradation. Al2O3 hollow fiber membranes were prepared using the phase inversion process. A dip-coating technique was used to deposit titanium dioxide (TiO2) and nitrogen-doped titanium dioxide (N-TiO2) thin films on well-cleaned Al2O3-based hollow fiber membranes. All heterogeneous photocatalytic degradation tests of NH3 gas were performed with both UV and visible light irradiation at room temperature. The nitrogen doping effects on the NH3 heterogeneous photocatalytic degradation capacity of TiO2 were investigated, and the effect of the number of membranes (30, 36, 42, and 48 membranes) of the prototype lab-scale photocatalytic membrane reactor, with a modular design, on the performances in different light conditions was also elucidated. Moreover, under ultraviolet and visible light, the initial concentration of gaseous NH3 was reduced to zero after only fifteen minutes in a prototype lab-scale stage with a photocatalytic membrane reactor based on an N-TiO2 photocatalyst. The number of Al2O3-based hollow fiber membranes functionalized with N-TiO2 photocatalysts increases the capacity for NH3 heterogeneous photocatalytic degradation.

Facile Construction of Nanofilms from a Dip-Coating Process to Enable High-Performance Solid-State Batteries.

The use of solid-state electrolytes (SSEs) instead of those liquid ones has found promising potential to achieve both high energy density and high safety for their applications in the next-generation energy storage devices. Unfortunately, SSEs also bring forth challenges related to solid-to-solid contact, making the stability of the electrode/electrolyte interface a formidable concern. Herein, using a garnet-type Li6.5La3Zr1.5Ta0.5O12 (LLZT) electrolyte as an example, we demonstrated a facile treatment based on the dip-coating technique, which is highly efficient in modifying the LLZT/Li interface by forming a MgO interlayer. Using polyvinyl pyrrolidone (PVP) as a coordination polymer, uniform and crack-free nanofilms are fabricated on the LLZT pellet with good control of the morphological parameters. We found that the MgO interlayer was highly effective to reduce the interfacial resistance to 6 Ω cm2 as compared to 1652 Ω cm2 of the unmodified interface. The assembled Li symmetrical cell was able to achieve a high critical current density of 1.2 mA cm-2 at room temperature, and it has a long cycling capability for over 4000 h. Using the commercialized materials of LiFePO4 and LiNi0.83Co0.07Mn0.1O2 as the cathode materials, the full cells based on the LLZT@MgO electrolyte showed excellent cyclability and high rate performance at 25 °C. Our study shows the feasibility of precise and controllable surface modification based on a simple liquid phase method and highlights the essential importance of interface control for the future application of high-performance solid-state batteries.

Controlled-Alignment Patterns of Dipeptide Micro- and Nanofibers.

Ordered assemblies of the peptide diphenylalanine (FF) are produced and deposited on planar substrates. The FF aggregate growth is achieved through precipitation from aqueous ammonia solutions induced by solvent evaporation. The applied dip-coating technique confines the FF assembly growth to a narrow zone near the three-phase contact. The growth was observed online by optical microscopy and was investigated systematically as a function of the process parameters. Depending on the external gas flow (to influence solvent evaporation), the withdrawal speed, the initial FF, and the initial ammonia concentrations, FF forms long, straight, and rigid microfibers and/or shorter, curved nanofibers. Under certain process conditions, the FF fibers can also aggregate into stripes. These can be deposited as large arrays of uniform stripes with regular widths and spacings. Scenarios leading to the various types of fibers and the stripe formation are presented and discussed in view of the experimental findings.

Super Broadband at Telecom Wavelengths From RE3+-Doped SiO2-Ta2O5 Glass Ceramics Planar Waveguides.

This paper reports on the preparation of Er3+/Yb3+/Tm3+, Er3+/Yb3+/Nd3+, and Er3+/Tm3+/Nd3+ triply doped and Er3+-doped SiO2-Ta2O5 glass ceramic nanocomposites and active planar waveguides by the sol–gel process using the dip-coating technique as deposition method. The investigation of their structural, morphological, and luminescent properties using XRD, AFM, and photoluminescence analysis, are reported here. The XRD results showed the presence of L-Ta2O5 nanocrystals dispersed in the SiO2-based amorphous host for all the nanocomposites and films. The rare earth ion (RE3+) doping concentration affected both the crystallinity, and the crystallite sizes of the Ta2O5 dispersed into SiO2-Ta2O5 nanocomposites and waveguides. AFM characterization revealed crack free and smooth surface roughness and differences in viscoelasticity on the Er3+-doped SiO2-Ta2O5 films surface, which allows the identification of Ta2O5 nanocrystals on the SiO2 amorphous host. The Er3+ doped and triply doped SiO2-Ta2O5 nanocomposites displayed broad- and super broadband NIR emissions with a FWHM up to 173 nm achieved in the telecom wavelengths. The lifetime of the 4I13/2 emitting level of the Er3+-doped SiO2-Ta2O5 waveguides is strongly dependent on Er3+ concentration and an emission quenching was negligible up to 0.81 mol%. The structural and luminescent investigations indicated that RE3+-doped SiO2-Ta2O5 glass ceramics are promising candidates for photonic applications in optical devices operating in wide wavelengths at the telecom bands.

Biomimetic and osteogenic natural HAP coated three dimensional implant for orthopaedic application

The excellent biocompatible and osteogenesis ability of multifunctional three-dimensional (3D) polymeric scaffolds have a vital role in bone regeneration application. Our prime focus of the investigation is the synthesis of snail shell-derived hydroxyapatite coated poly[bis(carboxyphenoxy)phosphazene] (PCPP)/poly(ε-caprolactone) (PCL) 3D scaffold. Snail shells are utilized for hydroxyapatite (HAP) synthesis via a modified chemical precipitation method. The interconnected PCPP/PCL polymeric scaffold was fabricated by the conventional solvent-casting/particulate-leaching method. Bioceramic HAP was further coated on the scaffold by the dip-coating technique. The obtained natural HAP from Turritella duplicata has minerals and organic substituents which are essential for biomedical application. HAP reinforcement significantly increases the mechanical property, compressive strength, and porosity of the scaffolds. The SEM image depicted the homogenous dispersion of HAP over the scaffold surface. Mechanical studies of the 3D polymeric scaffold at the 2% TSS-HAP content demonstrated a significant increase in compressive strength with desired porous structure. It showed increasing compressive strength from 1.52 MPa to 2.18 MPa and porosity of 82.26% to 76.18%. Snail shell HAP grafted polymeric scaffold shows mineralization with the formation of bone-like apatite. The HAP grafted bioceramic/polymeric scaffold surface helps in the attachment and proliferation of MG-63 cells. It also explored the biocompatible property and antibacterial against gram-positive/gram-negative bacteria. Overall, the fabricated 3D implant has improved mechanical strength, optimum pore size, and interconnected structure, which helps in mineralization and cancellous bone tissue engineering applications.

Zirconium oxide film deposition properties to build transparent electronic devices in conjunction with tin dioxide

ZrO2 thin films are deposited by the sol–gel dip-coating technique where the thermal annealing temperature and the number of deposited layers determine the properties of this material concerning the application in field-effect transistor (FET) devices in conjunction with SnO2 layer, also produced by sol–gel dip-coating. The best annealing temperature for the ZrO2 film was found as 400°C, along with a small number of layers and the position of the layer inside the oven, which determines the dominant heat transport mechanism of conduction or convection phenomena. The electrical insulating property of ZrO2 layers was confirmed with the current in the order of pA, even for layers about 100 nm thick. The temperature of 400°C also leads to a lower leak current through the gate in the device, which is three orders of magnitude lower than the source-drain current (in the order of a tenth of [Formula: see text]A).

Spin state bistability in (Mn, Zn) doped Fe(phen)2(NCS)2 molecular thin film nanocrystals on quartz

Spin state bistability within high spin (HS) and low spin (LS) state is investigated in undoped and (Zn, Mn) doped spin crossover (SCO) complex Fe(phen)2(NCS)2 thin films (thickness ∼ 300 nm) deposited by dip-coating technique at room temperature on the quartz substrate. The X-ray diffraction studies clearly show the formation of crystalline structure of SCO complexes. The growth of the thin films was indisputably confirmed by electron microscopy and optical studies. The optical absorption peak between 535-557 nm was clearly observed, and that corresponds to 1A1g → 1T1g ligand field absorption in undoped and metal-doped (Zn, Mn) SCO thin films. The high spin (HS) state of the SCO films at room temperature was confirmed by Raman spectra. The bistability of spin states is clearly revealed by the well pronounced thermal hysteresis loop in magnetization measurements. The spin transition temperature (T1/2) and loop width are found to be critically dependent on metal doping and suggested the possibility of tuning these parameters in spin-crossover thin films to design future spin-based devices.

Drug Delivery from PCL/Chitosan Multilayer Coatings for Metallic Implants.

Implant-related infections, mainly caused by Staphylococcus aureus, are a major health concern. Treatment is challenging due to multi-resistant strains and the ability of S. aureus to adhere and form biofilms on bone and implant surfaces. The present work involved the preparation and evaluation of a novel dual polymeric film coating on stainless steel. Chitosan and polycaprolactone (PCL) multilayers, loaded with poly(methyl methacrylate) (PMMA) microspheres encapsulating vancomycin or daptomycin, produced by the dip-coating technique, allowed local antibiotic-controlled delivery for the treatment of implant-related infections. Enhanced adhesion of the film to the metal substrate surface was achieved by mechanical abrasion of its surface. Studies have shown that for both drugs the release occurs by diffusion, but the release profile depends on the type of drug (daptomycin or vancomycin), the pH of the solution, and whether the drug is freestanding (directly incorporated into the films) or encapsulated in PMMA microspheres. Daptomycin freestanding films reached 90% release after 1 day at pH 7.4 and 4 days at pH 5.5. In comparison, films with daptomycin encapsulated microspheres reached 90% release after 2 h at pH 5.5 and 2 days at pH 7.4. Vancomycin encapsulated and freestanding films showed a similar behavior reaching 90% release after 20 h of release at pH 5.5 and 2 and 3 days, respectively, at pH 7.4. Furthermore, daptomycin-loaded films showed activity (assessed by agar diffusion assays) against sensitive (ATCC 25923) and clinically isolated (MRSA) S. aureus strains.

Towards facile fabrication of photonics components from inorganic and hybrid sol-gel films. Preparation and optical properties characterization

New trends towards development of integrated optics and miniaturization of photonic devices require fabrication of miniaturized photonic components. Fabrication of waveguiding films with designed optical properties is a fundamental process for production of planar integrated devices.We report here preparation of thin layers based on TiO2 precursor (TET – titanium(IV) ethoxide) and SiO2 precursors, namely inorganic (TEOS – tetraethyl orthosilicate) or organically modified (GLYMO − 3-glycidoxypropyltrimethoxysilane) as candidates for potential application in the planar integrated circuits.The thin layers were deposited on soda-lime glass substrates using the sol-gel method and dip-coating technique and processed at relatively low temperature (up to 300 °C). Several parameters e.g. a) the type of SiO2 precursor, b) the presence of complexing agent for TET and c) heat treatment temperature were tested for their influence on thickness and refractive index of the obtained films.Furthermore, a few series of sol-gel films activated with luminescent dye (Rhodamine B) was fabricated. The influence of the above-listed parameters on luminescent properties of the films was characterized because of lack of systematic study in the literature in this aspect. Moreover, a spectrum of the light at the output of a chosen luminescent dye-doped waveguiding film excited by laser source was investigated.In addition, the subject of our investigations were films prepared at 200 °C with various amounts of TET and organically modified SiO2 precursor in concentration range not presented before. Their optical properties such as homogeneity and values of optical band gap of TiO2 clusters were explored. For selected samples the waveguide properties including the optical losses were evaluated. For the first time, hybrid films with presented composition and refractive index in range of 1.59–1.71 were used for patterning by nanoimprint technique allowing for reproduction of periodic structures, which may serve for example as grating couplers or DFB (distributed feedback) resonators.

Fluoropolymer-based hybrid superhydrophobic nanocomposite coating with antifouling and self-cleaning properties for efficient oil/water separation

The production of industrial and domestic effluents possessing oily contaminated water has become a global concern as a result of environmental contamination and pollution. Newly synthesized organic-inorganic hybrid nanocomposites with special wetting and anti-wetting properties have been adopted in recent times to address this problem. However, this method has faced a few setbacks in curbing the situation, which leaves the problem persistent. In order to realize the full potential of hybrid composites in combating oil/water contamination, we synthesize a robust organic-inorganic superhydrophobic hybrid nanocomposite containing Polyvinylidene fluoride (PVDF) and silicon hydroxide (SiO2) to coat cellulose filter paper for effective and efficient separation of oil/water mixtures. With a simple dip-coating technique, the superhydrophobic hybrid composite obtain a superhydrophobicity with a water contact angle as high as 161˚ on the filter paper. The coated membrane possessed a robust mechanical property as well as chemical stability which withstands a sandpaper abrasion test of up to 80 cycles and could retain its superhydrophobicity in acidic, neutral and alkaline media after 24hrs of immersion respectively. Moreover, the coated surface possessed nanopores which allows it to be used in oil water separation applications both under pressure and gravity with a separation efficiency of up to 99.7 % and can also be recycled many times for use. The excellent antifouling and self-cleaning ability of the coated membrane also prevents the adhesion of contaminants from the surface. The outstanding performance of the facilely and cost-effective fabricated superhydrophobic hybrid composite reveals a great potential for curbing the problems of oil contamination while addressing some existing barriers to the full potential realization of hybrid composites.

Engineering multi-functionalized molecular skeleton layer for dendrite-free and durable zinc batteries

Aqueous Zn batteries are subject to uncontrollable dendrite growth and water-induced parasitic side reactions, resulting in poor Zn2+ kinetics and limited lifespan. Herein, a self-consistent ultrathin multifunctional layer by integrating hydrophobic siloxane-based block and zincophilic diphosphate-building block into molecular skeletons on Zn foils (MTSi-Hedp-Zn) is proposed by a scalable and low-cost dip-coating technique. Experimental results combined with theoretical calculation (DFT) and COMSOL Simulations reveal that abundant O-Si-CH3 groups as hydrophobic block in the top of molecular skeletons is the contributing factor in precluding solvated H2O corrosion. Zincophilic PO bonds on organic phosphate block in the backbone work as attraction area for fast Zn2+ adsorption and transport kinetics. Simultaneously, such a combination enables surface-preferred (002) crystal planes on Zn metal, synergistically homogenizing the electric field at the interface and achieving preferentially flat growth without dendrites and side reactions. Accordingly, the MTSi-Hedp-Zn electrode exhibits an extended lifespan of over 2000 h and a much low voltage polarization of ~24.3 and 67.5 mV at 1 and 10 mA cm−2, respectively. Practical full cells coupled with commercial cathodes (CNT/MnO2 and V2O5) both perform much better capacity retention than the bare Zn case. The proposed hydrophobic-zincophilic interface by silane-organic phosphoric acid provides a significant construction tactic for designing dendrite-free and corrosion-free Zn electrodes and beyond.

Preparation and Characterization of Supported Molybdenum Doped TiO2 on α-Al2O3 Ceramic Substrate for the Photocatalytic Degradation of Ibuprofen (IBU) under UV Irradiation

TiO2-based photocatalyst materials have been widely studied for the abatement of contaminants of emerging concerns (CECs) in water sources. In this study, 1.5 wt% Mo-doped HRTiO2 was obtained by the sonochemical method. The material was analyzed and characterized for thermal, structural/textural, morphological, and optical properties using TGA-DSC, XRD, TEM, FTIR, XPS, SEM-EDS, BET (N2 adsorption-desorption measurement and BJH application method), and UV-Vis/DRS measurement. By the dip-coating technique, ~5 mg of Mo/HRTiO2 as an active topcoat was deposited on ceramic. In suspension and for photocatalyst activity performance evaluation, 1 g/L of 1.5 wt% (Mo)/HRTiO2 degraded ~98% of initial 50 mg/L IBU concentration after 80 min of 365 nm UV light irradiation and under natural (unmodified) pH conditions. Effects of initial pH condition, catalyst dosage, and initial pollutant concentration were also investigated in the photocatalyst activity performance in suspension. The photocatalyst test on the supported catalyst removed ~60% of initial 5mg/L IBU concentration, while showing an improved performance with ~90% IBU removal employing double and triple numbers of coated disk tablets. After three successive cycle test runs, XRD phase reflections of base TiO2 component of the active photocatalyst supported layer remained unchanged: An indication of surface coat stability after 360 min of exposure under 365 nm UV irradiation.

Advancement of stannite Cu2CoSnS4 thin films deposited by sol gel dip-coating route

In this research effort, we synthesized copper-cobalt-tin-sulphur Cu2CoSnS4 (CCoTS) absorbers by sol–gel process associated with the dip-coating deposition technique on the ordinary glass substrates. We synthesized the impact of annealing temperature without utilization sulfurization on the structural, compositional, morphological, optical and electrical characteristics of layers annealed at 280 °C, 300 °C, 320 °C and 340 °C. CCoTS absorbers have been controlled by different control techniques included x-ray diffraction (XRD), Raman spectroscopic, Energy dispersive x-ray spectroscopy (EDS), Scanning electron microscopy (SEM), UV–vis spectroscopy and four-point probe technique (FPP). XRD patterns exhibited a polycrystalline structure with peaks agreeing to the (112), (204) and (312) directions and matching well with those of the pure stannite phase of CCoTS. The size of crystallites was found in the variety of 8.23–11.27 nm. Raman spectroscopic presented a peak at 332 cm−1 which is the signature of the pure stannite phase of CCoTS. EDS analysis measurements presented a close stoichiometric CCoTS thin films composition. SEM micrographs demonstrated an enhancement in films density and uniformity with annealing temperature rises. It was found that the band gap decreased from 1.72 to 1.5 eV with rising of annealing temperature. The sheet resistance was observed between 27.83 and 56.23 Ω sq−1. These properties are quite interesting and can make the dip-coater CCoTS films as suitable novel absorbers for photovoltaic devices.

Fabrication and Performance of Micro-Tubular Solid Oxide Cells

Solid Oxide Cells (SOC) are the kind of electrochemical devices that provide reversible, dual mode operation, where electricity is generated in a fuel cell mode and fuel is produced in an electrolysis mode. Our current work encompasses the design, fabrication, and performance analysis of a micro-tubular reversible SOC that is prepared through a single dip-coating technique with multiple dips using conventional materials. Electrochemical impedance and current-voltage responses were monitored from 700 to 800 °C. Maximum power densities of the cell achieved at 800, 750, and 700 °C, was 690, 546, and 418 mW cm−2, respectively. The reversible, dual mode operation of the SOC was evaluated by operating the cell using 50% H2O/H2 and ambient air. Accordingly, when the SOC was operated in the electrolysis mode at 1.3 V (the thermo-neutral voltage for steam electrolysis), current densities of −311, −487 and −684 mA cm−2 at 700, 750 and 800 °C, respectively, were observed. Hydrogen production rate was determined based on the current developed in the cell during the electrolysis operation. The stability of the cell was further evaluated by performing multiple transitions between fuel cell mode and electrolysis mode at 700 °C for a period of 500 h. In the stability test, the cell current decreased from 353 mA cm−2 to 243 mA cm−2 in the fuel cell mode operation at 0.7 V, while the same decreased from −250 mA cm−2 to −115 mA cm−2 in the electrolysis operation at 1.3 V.

Preparation of α-alumina/γ-alumina/γ-alumina-titania ceramic composite membrane for chloride ion removal

It is a universally acknowledged truth that ceramic membranes with high heat and chemical resistance play a crucial role in the nanofiltration (NF) process under harsh conditions. Although the ceramic membranes are challenging to use for salt filtration due to pore size and surface charge constraints. In this study, sol-gel and dip-coating techniques are used to make alumina–titania composite ceramic membranes with an γ-alumina interlayer for salt rejection. Then, particle size distribution was determined using dynamic light scattering (DLS), and membrane surface quality and morphology were examined using scanning electron microscopy (SEM). The microstructural properties of the membrane have been investigated using X-Ray Diffraction (XRD). A dead-end module is used to measure water permeability and salt rejection. After calcination at 450 °C, SEM shows the crack-free membrane surfaces. The interlayer and top layer membrane thicknesses were estimated to be 1.5 and 0.5 μm, respectively. In addition, XRD measurements show an alumina crystal structure for the interlayer and anatase, rutile, and alumina phases for the composite membranes. Finally, it was shown that the amount of chlorine rejection was pH-dependent, with the rejection rate increasing from 12.7% to 67% as the pH climbed from 4 to 12. Overall, this research provides a composite ceramic nanofiltration for high-pressure desalination, and it is shown that the membrane's surface does not alter after five cycles, which allows for a long-term chemical process and it could be a promising candidate in the wastewater treatment field.