Doctor Blade Method Research Articles

Effect of cadmium sulphide on poly (ethyl methacrylate) (PEMA) based electrolyte nanocomposite and its application in dye sensitized solar cell (DSSC)

The detail study of structural and ionic conductivity characterization of Poly (ethyl methacrylate) (PEMA) based polymer composite electrolyte were modified by the incorporation of Cadmium sulphide (CdS) nanomaterial. PEMA in addition with 40 % wt. potassium iodide (KI) and ethylene carbonate (EC) having 60 % wt., has the highest ionic conductivity of 4.65 × 10−5 S/cm when employed the solution casting technique. Cadmium Sulphide (CdS) was incorporated with PEMA + KI 40 % wt. + EC 60 % wt. sample to get maximum conductivity sample. The highest ionic conductivity 2.65×10−3S/cm, was attained at 7 % weight percentage of Cadmium sulphide (CdS). The conductive sample's morphology was examined using SEM, its amorphicity and crystalline structure was investigated using Fourier transform infrared (FTIR) technique, and FTIR 'wavenumbers of the maximum conductive sample of PEMA polymer + KI salt + EC plastizer and PEMA polymer + KI salt + EC plastizer + CdS nanoparticles were compared. X-ray diffraction (XRD) was used to identify the amorphous nature of the maximum conductive sample of polymer composite electrolyte. Differential scanning calorimetry (DSC) analysis was used to find out the glass transition (Tg) temperature of maximum conducting sample of polymer composite. The doctor blade method was employed to develop the dye sensitized solar cell (DSSC), and it had been observed that, under one sunlight situation, the energy conversion efficiency was 2.09 %, having parameters fill factor was 79.77 %.

Fabrication and performance assessment of coin cell supercapacitors with multiwalled carbon nanotube-supported mixed metal oxide nanocomposites and redox additive electrolyte

In the realm of supercapacitor applications, the fabrication of coin cell supercapacitors with superior performances played a crucial role. In this work, an asymmetrical type coin supercapacitor was fabricated with multiwalled carbon nanotube supported mixed metal oxide (CuO/CoO@MWCNT - CCM) nanocomposites (NCs) and potassium ferrocyanide incorporated KOH based redox additive electrolyte (RAE). The synergistic effect and the enhanced conductivity by the mixed metal oxides and MWCNT, respectively, were acted as the performance enhancer for electrode performances. On the other hand, RAE with optimized concentration provided additional redox active sites for superior performances. The combined effect of CCM NCs and RAE, were responsible for the superior performances. CCM NCs were prepared by one-pot hydrothermal technique and characterized. Working electrodes with CCM NCs were fabricated by doctor blade method and evaluated in KOH and RAE. It exhibited 1838.55 Fg−1 of specific capacitance (Csp) in RAE. Assembled asymmetrical supercapacitors with CCM NCs modified working electrode and activated carbon based anode, delivered 123.91 Fg−1 of Csp at 2.75 Ag−1 in RAE. The assembled supercapacitors delivered the highest energy density of 27.53 Wh kg−1 and power density of 1875 W kg−1 in RAE with an impressive 82.89 % of cyclic retention after 5000 GCD cycles. Finally, an asymmetric coin cell supercapacitor (CR2302) was fabricated with CCM NCs and RAE. The fabricated coin cell delivered the charge and discharge capacities of 157.72 and 55.99 mAh g−1, respectively in KOH, whereas these values were significantly improved 172.46 and 126.2 mAh g−1 respectively, in RAE. It proved that the fabricated coin cell supercapacitors performed well in terms of maximum charge and discharge performances in RAE compared to conventional KOH.

Mechanochemical synthesis and characterization of poly[(aniline-co-N-(4-sulfophenyl) aniline] nanofibers and its nanocomposite with titanium dioxide nanoparticles and study of their efficiency in hybrid solar cell

The advantages of polyaniline for application in new generation solar cells include its cost-effectiveness, environmentally friendly synthesis, remarkable stability, and the ability to modify the bandgap through the synthesis of its nanocomposites. But a challenge for its nanostructures is the limited solubility in non-toxic solvents, including water, which limits their processability in coating techniques. We overcame this challenge by synthesizing its copolymer with diphenylamine-4-sulfonate and its nanocomposite with titanium dioxide nanoparticles (TiO2NPs). So through a solid-state and template-free technique and using sodium diphenylamine-4-sulfonate, aniline hydrochloride salt, TiO2NPs, and FeCl3∙6 H2O as an oxidant, poly(N-(sulfophenyl)aniline) nanoflowers (PSANFLs), poly [(aniline-co-N-(4-sulfophenyl) aniline] nanofibers (PAPSANFs), poly(N-(sulfophenyl)aniline) nanofibers/titanium dioxide nanoparticles (PSANFs/TiO2NPs), and poly (aniline-co-N-(4-sulfophenyl)aniline nanofibers/titanium dioxide nanoparticles (PAPSANFs/TiO2NPs) were synthesized. Characterization of the synthesized samples was carried out through field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectra, ultraviolet-visible spectra (UV-Vis), cyclic voltammetry (CV), and elemental analysis (CHNS). The FE-SEM images clearly illustrate that the synthesized samples are of nanoscale dimensions. The band gap values of 2.23 eV for PSANFs/TiO2NPs and 1.96 eV for PAPSANFs/TiO2NPs nanocomposites were determined through electrochemical calculations based on cyclic voltammetry curves, showcasing the complementary properties of n and p semiconductors. Using doctor blade method to prepare films from synthesized materials and the architectural pattern of ITO│TiO2NPs│semiconductor sample│Al, all hybrid solar cells are fabricated. The I-V characteristics and power conversion efficiency (PCE) of the samples were examined and discussed. The PCE values for the four samples were found to be in the range of 0.20–0.82 %.

Crystallinity Reconstruction of Squid-Pen Chitosan into Mechanically Robust and Multifunctional Bionanocomposite Food Packaging Film.

First, we explore the effect of bioacids on the film processing of preprocessed, i.e., deacetylated, chitosan (d-chitosan with molecular weight of 1,000,000 kDa), using monocarboxylic acid (acetic acid), dicarboxylic acid (malic acid), and tricarboxylic acid (citric acid) as model weak acidic solvents to destabilize the hydrogen bonding and transform crystal structures into film. Second, we investigate the chemical and physical toughening effect in the bionanocomposite film composed of cross-linkable multicarboxilic acid, i.e., succinic acid (SA). In doing so, the addition of glycerol as a plasticizer can increase polymer chain mobility, making the biocomposite film more ductile and flexible. The addition of CNC also enhances the tensile strength (41.6%), swelling (43.47%), and oxygen barrier properties (38.81%), as well as significantly improves UV light barrier. The excellent antibacterial properties (99.9% efficiency against S. aureus and K. pneumoniae) of the prepared biocomposite films are found to be independent of the presence of glycerol or CNC. Third, the development of film processability under an industrially relevant process is also demonstrated by doctor blade method. It is found that film processability of the squid-pen's chitosan bionanocomposite can straightforwardly be compatible with and improvable in the presence of poly(vinyl alcohol) employed as a model biodegradable processing aid.

A carbon electrode approach for TiO2-write-once-read-many resistive memories

Nanomaterials are a potential alternative to conventional random resistive access memory (ReRAM) in non-volatile memory (NVM) due to their unique electrical and physical properties. Nevertheless, obtaining a specific NVM characteristic [particularly Write-Once-Read-Many (WORM)] using carbon-based electrodes necessitates further assessment. This study proposed a reinvented methodology for TiO2-based devices to produce WORM memory behavior using the doctor blade method. A carbon/graphite counter electrode (Gr/Cb) was fabricated and characterized for TiO2-based resistive switching devices. Consequently, the Gr/Cb electrode device quickly transitioned from a high to low resistance state, suggesting WORM memory behavior. Approximately 66.7 % improvement (∼1.8 V–∼0.6 V) was observed in the required applied voltage when the active area was reduced, indicating lower power consumption. Overall, this study provided evidence of the approach's feasibility in practical applications, demonstrating lower costs and simplicity. The structure also highlighted the importance of understanding the WORM behavior for effectively utilizing carbon-based electrodes in non-volatile memories.

Dual-capable spinel cobalt oxide nanoparticles for electrocatalytic oxygen evolution and water contaminant removal.

This study investigates the synthesis and electrocatalytic performance of cobalt oxide (Co3O4) nanoparticles for the oxygen evolution reaction (OER) and their role in water treatment as contaminant removal agents. Cobalt oxide nanoparticles are recognized as promising materials in electrocatalysis due to their tunable properties and nanoscale engineering potential. Here, fine cobalt oxide nanoparticles are synthesized using the sol-gel method followed by various sintering temperatures to achieve precise control over surface morphology, size, and shape. Characterization via high-resolution scanning electron microscopy (HRSEM) and high-resolution transmission electron microscopy (HRTEM) elucidates the impact of sintering temperature on nanoparticle properties. Thin film electrodes of cobalt oxide are fabricated using the doctor blade method and evaluated using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). Among the tested sintering temperatures, cobalt oxide electrodes sintered at 600°C exhibit superior catalytic activity, demonstrating an overpotential of 258mV (vs RHE) at 10mAcm-2 current density and a Tafel slope of 17.33mV dec-1. Furthermore, these electrodes demonstrate excellent stability, maintaining OER performance for 10h in 1M NaOH electrolyte. Additionally, the role of cobalt oxide nanoparticles in water treatment is explored using inductively coupled plasma atomic emission spectrometry (ICP-AES). Experimental results reveal that lower sintering temperatures enhance the electrocatalytic properties of cobalt oxide nanoparticles, highlighting their potential contribution to sustainable energy and water treatment technologies. This work underscores the significance of cobalt oxide nanoparticles as dual-functional materials for advancing electrocatalysis and water purification applications, thus paving the way for the development of efficient and environmentally friendly technologies.

Electrosynthesis of Metal–Organic Framework Interlayer to Realize Highly Stable and Kinetics‐Enhanced Zn Metal Anode

AbstractTo facilitate the practical application of aqueous Zn metal batteries, numerous artificial interlayers are designed to mitigate rampant parasitic reactions and uncontrollable dendrite growth on the Zn metal anode. Traditionally, these interlayers are prepared through the doctor blade method. However, the introduced insulting binder generally compromises their interfacial performance. In this study, the metal–organic framework (MOF) interlayer is fabricated on the Zn metal anode by a facile and binder‐free electrosynthesis technique. The electrosynthetic Co‐ZIF‐8 interlayer enables the Zn metal anode to sustain cycles of 1280 h with a low voltage hysteresis. Moreover, the full cells coupled with MnO2 and NH4V4O10 cathodes exhibit exceptional cycling performance, maintaining 89% and 72% of their initial capacity after numerous cycles, respectively. Based on SEM measurements and density functional theory calculations, the densely packed morphology, unimpeded Zn2+ ions transport channels, and affinity of the imidazole ring and Co node within the ZIF‐8 structure to Zn atom are demonstrated to inhibit parasitic reactions, promote Zn2+ ions transport, and realize uniform Zn deposition. The proposed electrosynthesis method for constructing the MOF interlayer provides a straightforward and reliable approach to developing a highly stable Zn metal anode.

(Digital Presentation) Integrated Membrane Electrode Assembly in Proton Exchange Membrane Fuel Cells

Proton exchange membrane fuel cells (PEMFCs), an electrical device with high energy conversion efficiency and zero-carbon emission, has attracted more attention. The membrane electrode assembly (MEA) is the core component of PEMFCs, mainly including proton exchange membrane (PEM), catalyst layer (CL), microporous layer (MPL) and carbon fiber gas diffusion layer (GDL), which has different structures and significantly affects its power density and durability [1].Generally, MEA is fabricated by catalyst coated electrodes (CCE) and catalyst coated membrane (CCM) methods, which often results in a huge interface resistance between electrode and membrane, the weak adhesion and poor proton and electron transfer, limiting the electrochemical surface area (ECSA) and the power density of PEMFCs [2].To solve this problem, many approaches have been adopted, such as improving sintering temperature for MEA, incorporating a guided cracked layer between cathode and membrane, double-layered catalyst and direct deposition method. Zhao et al prepared an integrated membrane electrode assembly structure to reduce the contact resistance between proton exchange membrane and catalyst layer, which significantly improves the efficiency and stability of water electrolysis [4]. At the same time, Klingele and Breitwieser developed a direct deposition of proton exchange membrane technology to improve high performance and long-term stability of PEMFCs. However, these methods are complex and almost impossible to industrialize [5].In this study, integrated membrane electrode assembly (I-MEA) was prepared by combining casting and doctor blade method techniques. The results show that the casting method is more suitable for fabricating I-MEALT in low-temperature proton exchange membrane fuel cells. The power density of the I-MEALT cell is increased by 18% compared with that of the conventional MEALT (Fig. 1). The doctor blade method is more suitable for preparing I-MEAHT in high-temperature proton exchange membrane fuel cells. The maximum power density of I-MEAHT is increased by about 57% compared with that of the conventional MEAHT. The electrochemical impedance shows that this is mainly attributed to the reduced interface resistance between the electrode and the membrane, which facilitates the proton transfer.

Synthesis of Bi2S3-sensitized TiO2 photoanodes for enhanced photovoltaic performance in solar cell application

The synthesis of Bi2S3 nanoparticles for sensitizing TiO2 photoanodes were synthesized through a cost-effective and straightforward approach using modified chemical bath deposition (M-CBD) or successive ionic atomic layer adsorption reactions (SILAR) at room temperature. Initially, a TiO2 seed layer was synthesized at room temperature via the chemical bath deposition method, followed by deposition of a mesoporous TiO2 layer using the doctor blade method. This study investigated the influence of the number of SILAR cycles and the choice of counter electrodes on the performance of Bi2S3/TiO2-based photoelectrodes. Characterization of the prepared Bi2S3/TiO2 photoanode involved various techniques, including X-ray diffraction, UV–Vis spectroscopy, scanning electron microscopy, and Raman spectroscopy, enabling the analysis of its structural, optical, and morphological properties. The Bi2S3/TiO2-based cell exhibits a maximum conversion efficiency of 0.8%, demonstrating the potential of this combination for photovoltaic applications. This study contributes to the field of solar cell technology by presenting a novel approach for sensitizing TiO2 photoanodes with Bi2S3 nanoparticles, offering insights into the optimization of fabrication parameters and performance enhancement strategies for future device design and development.

Amplifying Photochromic Response in Tungsten Oxide Films with Titanium Oxide and Polyvinylpyrrolidone.

Tungsten oxide (WO3) is known for its photochromic properties, making it useful for smart windows, displays, and sensors. However, its small bandgap leads to rapid recombination of electron-hole pairs, resulting in poor photochromic performance. This study aims to enhance the photochromic properties of WO3 by synthesizing hexagonal tungsten oxide via hydrothermal synthesis, which increases surface area and internal hydrates. Titanium oxide (TiO2) was adsorbed onto the tungsten oxide to inject additional charges and reduce electron-hole recombination. Additionally, polyvinylpyrrolidone (PVP) was used to improve dispersion in organic solvents, allowing for the fabrication of high-quality films using the doctor blade method. Characterization confirmed the enhanced surface area, crystal structure, and dispersion stability. Reflectance and transmittance measurements demonstrated significant improvements in photochromic properties due to the composite structure. These findings suggest that the introduction of TiO2 and PVP to tungsten oxide effectively enhances its photochromic performance, broadening its applicability in various advanced photochromic applications.

The Effect of Mixed Dye Composition of Anthocyanin-Chlorophyll on DSSC Efficiency on TiO2/ZnO Semiconductors

The effect of mixed dye composition of anthocyanin-chlorophyll on DSSC efficiency on TiO2/ZnO semiconductors aims to determine the effect of using dye containing anthocyanin-chlorophyll on the absorbance value and work efficiency value of Dye Sensitized Solar Cell (DSSC). The TiO2/ZnO was deposited using the doctor blade method and the dye was made using the maceration method. The counter electrode was made on FTO glass coated by calcined battery carbon with temperature in 450°C. The DSSC assembly was arranged in a sandwich shape. Then electrolyte is dripped in the middle of the DSSC layer. Characterization tests were carried out to determine the dye absorbance value and gap energy value using a UV-Vis spectrophotometer. DSSC efficiency testing uses current and voltage (I-V) characterization. DSSC testing was carried out using a multimeter with a light source from sunlight. The results of UV-Vis characterization showed that the highest absorbance value was obtained for the kale-mangosteen peel dye at a wavelength of 530 nm with an absorbance of 5.234%. The TiO2/ZnO gap energy obtained using the touch plot method is 2.42 eV. The highest efficiency value was obtained from the kale-mangosteen peel dye mixture of 0.0286%. There was an increase in the DSSC efficiency value when the dyes were combined.

Synthesis and characterization of copper tin sulfide counter electrode for enhanced performance in third-generation solar cells

This paper presents the fabrication of a copper tin sulfide (CTS) counter electrode for application in third-generation solar cells. The fabrication process involved modified chemical bath deposition (M-CBD) or a successive ionic layer adsorption reaction (SILAR). Initially, a ZnO seed layer was deposited onto a fluorine-doped tin oxide (FTO) substrate via CBD. Subsequently, a mesoporous layer of ZnO was deposited onto the FTO substrate using the doctor-blade method. The mesoporous ZnO layer was sensitized with CdS nanocrystals deposited using the SILAR method. Various characterization techniques, including UV–Vis spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM), were employed to analyze the optical, structural, and morphological properties of the photoanode and CTS counter electrode. The results demonstrate the successful synthesis of a CTS counter electrode with desirable properties for solar-cell applications. The fabricated CTS counter electrode exhibited a conversion efficiency of 0.49%, which was significantly higher than that of carbon-based counter electrodes.

Study of the Optical and Structural Properties of Metal-Doped Titanium Dioxide Electrode Prepared by the Sol-Gel Method for Dye-Sensitized Solar Cells

This study presents a strategy to increase the efficiency of dye-sensitized solar cells (DSSCs) by doping titanium dioxide (TiO2) with different magnesium (Mn) concentrations (1, 3, 5, 7, and 9%) generated by the sol-gel process and effectively employed as a photo-anode (the working electrode) for DSSCs. The Doctor Blade method coated the indium-doped tin oxide (ITO) glass with a thin film layer. X-ray diffraction (XRD) was used to evaluate the characteristics of undoped and manganese-doped TiO2, and the results demonstrate that all of the thin films are anatase. The samples were examined using XRD to assess grain size before and after Mn doping. The spectrum of UV-Vis absorption changes; accordingly, as doping increases, the energy gap decreases. The smallest energy gap's value (2.4 eV) is 7% manganese doping. AFM pictures show the average roughness and root mean square of the weight percentage of films doped with 5%. Field effect scanning electron microscope (FE-SEM) studies show that the particle size of thin films gets smaller as more Mn is added, which happens at least as much as 7% Mn doping. The optimal thickness for TiO2 paste over conductive glass is 15 μm, and the cell's power conversion efficiency increased to 0.604074% with an Imax of 4.965 mA, a Vmax of 0.488 V, and a fill factor (FF) of 68.45954%.

Study of Fabrication Process and Performance Analysis of the CDS/CDTE Based Photovoltaic Cell

Fabrication of CDS/CDTE based heterojunction photovoltaic cell has been undertaken to explore better light conversion efficiency. We have developed a photovoltaic cell using glass coated with Indium doped Tin Oxide (ITO) which works as transparent conducting oxide (TCO). ITO coated glass has promising prospects of enhancing the efficiency of the photovoltaic cell. ITO layers are known to be employed as anode terminal due to the negative polarity they possess compared to the whole PV cell; here, we have employed it for the same function as the front layer. During fabrication of the photovoltaic cell, the deposition of nanoparticles of CDS and CDTE layer is undertaken through doctor-blade method. We have employed pure CDS as window layer for its high band gap of 3.8 eV (particle size: 8 nm) and CDTE as absorber layer due to its high optical absorption coefficient with high mobility, good carrier lifetime and enhanced crystallographic properties. The CDS window layer and CDTE absorber layer together constitute a p-n junction where the CDS window layer captures high intensity photons and transmits the photo-excited electron to CDTE absorber layer, thereby leading to photo-current output, which serves as a base to explore and test its further applications. To obtain band gap of respective CDTE and CDS nanoparticles, optical characterization is used. Silver paste is used as rear contact to form anode terminal having good conductivity and providing better mechanical support to the photovoltaic cell.

Syntheses of diphenolic resin based anti-corrosion coating material and reinforce its performance through MWCNT-Ag and MWCNT-Ag/PANI nanofillers

In the present work, a novel anti-corrosion coating material was developed using diphenolic resin and multiwalled carbon nanotube (MWCNT) based nanofillers. In this concern, phenylmethylene diphenolic resin (PMD) and its 2-(4-methylbenzyl) oxirane derivative (PMDD) were synthesized using phenol and benzaldehyde. Silver-decorated MWCNT (MWCNT-Ag) and polyaniline (PANI) synthesized on MWCNT-Ag (MWCNT-Ag/PANI) were also fabricated and employed as filler materials to enhance the anti-corrosion performance of PMDD. The resins were analyzed by LC-MS and FT-IR, and the nanofillers were characterized using XRD, SAED, EDX, TEM, and XPS techniques. The synthesized PMD and PMDD and different weight percentages of fillers blended PMDD were coated on the mild steel (MS) sample using doctor blade method. The surface morphology and roughness of the coatings were examined by SEM and AFM analyses. The anti-corrosion ability of the coated samples was assessed by electrochemical impedance spectroscopy (EIS) and salt spray testing (SST). All the results showed an excellent anti-corrosion performance of PMDD by the incorporation of 0.2 wt% of MWCNT-Ag/PANI. Withstanding the 5 wt% NaCl salt spray atmosphere for about 144 h and >460 days in 3.5 wt% NaCl solution reflects its strong barrier property and long-term durability. The cross-linking of resins, blockade of defects by nanofiller and an additional protective layer developed by conductive PANI make the coating material efficient and durable in highly corrosion environments.

Carbon gas sensors synthesized using acacia auriculiformis tree branches to detect methanol, ethanol, acetone vapors and ammonia gas

Metal oxides and carbon are the prime candidates of gas sensor devices. For the inaugural instance, carbonaceous particulate matter was meticulously derived from the branches of Acacia auriculiformis tree indigenous to Sri Lanka to detect vapor and gas. It is worth noting that biomass derived carbon had hitherto remain unexplored in the realm of vapor and gas detection. Carbon films were fabricated via the doctor blade method. The resistivity characteristic of these carbon samples exhibited discernible variations upon exposure to methanol, ethanol, acetone vapors, and ammonia gas. Notably, the gas-sensing properties of sample derived from the central core and the outer shell of Acacia auriculiformis tree branches were independently assessed in these vapors and gas at ambient temperature. Various analytical techniques, including X-ray diffraction (XRD), UVvisible absorption spectroscopy, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM), were judiciously employed to scrutinize the structural attribute, optical band gap, chemical composition and surface morphology of the aforementioned carbon film samples, respectively. XRD analyses unequivocally confirmed the successful formation of carbonaceous films. FTIR spectra conspicuously delineated the presence of oxygen within the carbon films. Importantly, the optical band gap of our carbon films manifested within the range characteristic of organic carbon. Furthermore, the resistance of the carbon films demonstrated a significant reduction upon adsorption of each vapor. It is noteworthy that while gas sensitivities and response times were superior for carbon derived from the central core of the Acacia tree branches, the recovery times were notably expedited for carbon synthesized from the outer shell of these branches. The zenith of gas sensitivity, an impressive 187%, was recorded in response to 1000 ppm of methanol vapor, when employing carbon sourced from the central core of the acacia tree branches.

Nymphaea Alba for Resistive Switching Devices: Exploring the Non‐Volatile Memory and Neuromorphic Computing Applications of the Plant Leaves

AbstractBiomaterial‐based resistive switching memory is one promising technology that could significantly impact the current direction of non‐volatile memory and neuromorphic computing. Given this, we report the fabrication of a resistive switching (RS) device based on Nymphaea Alba as an active switching layer and investigate its RS properties for memory and neuromorphic computing applications. The Nymphaea Alba switching layer was deposited by the conventional doctor blade method. Further, this is characterized by various analytical techniques. The fabricated device showed bipolar RS behavior and demonstrated good non‐volatile memory properties. Additionally, the device mimics various synaptic properties of the human brain, such as potentiation‐depression, Excitatory post‐synaptic current (EPSC), and Paired‐pulse facilitation (PPF). The charge‐flux relation reveals the non‐ideal memristor‐type behavior of the device. The Ohmic and Child's square law dominates the conduction of the device and the filamentary process responsible for the RS process of the device. These results show that the Nymphaea Alba is a promising biomaterial for non‐volatile memory applications.

Multi-layer shearing induced high orientation of graphene oxide sheets towards high-performance macrostructures

The orientation of graphene nanosheets in microstructures is directly related to the mechanical properties and thermal conductivity of graphene-based macrostructures. However, efficient and scalable modulation of the orientation of 2D graphene nanosheets remains challenging. Herein, a simple and effective approach was proposed by introducing a multi-layer shearing field in thick graphene oxide (GO) gel coatings to improve the total orientation of GO films. Hydrodynamic simulations were performed via the lattice-Boltzmann method to reveal the microscale mechanism of the flow profile in improving the orientation of GO nanosheets. The result was experimentally verified by fast Fourier transform (FFT) of the cross-section scanning electron microscope (SEM) images of freeze-dried GO films and wide-angle X-ray scattering (WAXS) patterns of 16 various samples under different shearing line distances, velocities, and GO concentrations. The obtained GO films exhibit high orientation (Herman's orientation factor ƒ = 0.922), high strength (419.2 MPa), and high modulus (26.2 GPa), respectively, which are 1.06, 5.57, and 3.49 times higher compared to GO films prepared through the frequently used doctor blade method. The good orientation of GO is remained and further improved to the ultra-high orientation (ƒ = 0.968) after being graphitized at 3150 °C and roll pressing, and the oriented thick graphene films achieved the highest thermal conductivity (1629 W m−1 K−1 for 86 μm and 1593 W m−1 K−1 for 110 μm) compared to other graphene films mentioned in the literature as having a similar thickness. The multi-layered shearing strategy represents a facile technology for assembling two-dimensional (2D) nanoscale building blocks into a macroscopic structure with good orientation and high performance.

Fabrication, characterization and application of W/N co-doped zinc oxide nanoparticles as a promising photoanode for dye-sensitized solar cells

In the present investigation, undoped, W doped, and W/N co-doped ZnO nanoparticles were prepared by sol–gel route. Here, the ZnO layers were fabricated via the doctor blade method. Hexagonal wurtzite structure is determined by XRD studies. The formation of a hexagonal wurtzite structure was observed from X-ray powder diffraction (XRD) resulting in a slight increase in crystallite size with an increase in doping content. The UV observation shows that W/N co-doping shifted the absorption spectra towards a higher wavelength and reduces the band gap energy. The EDS spectra confirms the high purity and triumphant doping of the W(tungsten) and N(nitrogen) into the ZnO lattice. The morphology of undoped and W/N co-doped ZnO nanoparticles was demonstrated by using FESEM and HRTEM. The 2 % W and 1.5 % N co-doped ZnO photoanode based DSSC (dye-sensitized solar cells) gained the highest short circuit current density of 8.44 mAcm−2 having an open-circuit voltage of 0.65 V, and PCE (power conversion efficiency) of 3.60 %.

The fabrication of integrated proton exchange membrane fuel cells: Excellent mechanical strength and electrochemical performance

Traditional membrane electrode assembly, prepared by catalyst coated electrodes (CCE) and catalyst coated membrane (CCM), has a huge interface between electrodes and membranes, which affects the mechanical adhesion, proton/electron transfer and gas/liquid transport in proton exchange membrane fuel cells (PEMFCs). In this study, an integrated membrane electrode assembly (I-MEA) was fabricated by the casting and doctor blade methods for low- and high-temperature PEMFCs, respectively. The results show that the maximum power density of I-MEALT is improved around 18% and its stripping force increased from 6.091 N to 7.387 N. I-MEAHT reached 0.418 W/cm2, which is 1.5 times higher than that of traditional MEAHT. Meanwhile, it achieved the maximum stripping force of 9.374 N.