Drop-casting Method Research Articles

Anticorrosive effect of green sulfonated PANI-Zn with epoxy for the corrosion protection of aluminum alloy 6061-T651

The synergistic effect of epoxy resin and PANI-metal composites in anti-corrosion coatings is well known. However, the conventional chemical synthesis of PANI and its composites generates environmentally hazardous waste on an industrial scale. Given this, the study proposes synthesis of PANI-Zn composites by a “green” method to protect the AA6061-T651 alloy against corrosion. For the synthesis, hydrogen peroxide and sulphuric acid were used to promote polymerization and doping. PANI-Zn were characterized by FTIR, UV–Vis, XPS, XRF, ICP-OES and SEM. To prepare the coatings, 10 mg of composites were dissolved in 500 μL of ethanol/NMP solution (1:1) and mixed with 500 mg of epoxy resin and 250 mg of hardener. These were applied to AA6061-T651 alloys by the drop-casting method and allowed to stand at room temperature for 7 days, followed by heating at 70 °C for 1 h. After curing, the coatings were subjected to morphological (SEM and AFM), adhesion tests and electrochemical (EIS and linear polarization) characterizations. FTIR and UV–Vis spectra confirmed the structure of PANI in the materials. They also show that the composites are sulfonated and partially oxidized. XPS analysis demonstrated that the composites are in the protoemeraldine state (0 < y < 1; y ≠ 0.5) and that the presence of Zn in the synthesis influences the oxidation and doping state of the PANI. Furthermore, the XPS spectrum showed a weak ZnO signal only in PZn4, probably due to the amount of Zn used in the synthesis. However, XRF and ICP-OES confirmed the presence and content of zinc oxide in samples. Indeed, the anticorrosion performance of the composites varied according to their composition. The E-PZn2 (Epoxy-PANI-2 % Zn) was the best-performing coated electrode due to the morphology and distribution of the composites in the epoxy resin as well as good adhesion. This resulted in a better barrier effect against the penetration of corrosive ions, as well as providing anodic and cathodic protection by PANI, hydrogen sulfate ions, and ZnO.

Ternary Holey Carbon Nanohorn/Potassium Chloride/Polyvinylpyrrolidone Nanohybrid as Sensing Film for Resistive Humidity Sensor

The study presents findings on the relative humidity (R.H.) sensing capabilities of a resistive sensor. This sensor utilizes sensing layers composed of a ternary nanohybrid, consisting of holey carbon nanohorn (CNHox), potassium chloride (KCl), and polyvinylpyrrolidone (PVP), with mass ratios of 7/1/2, 6.5/1.5/2, and 6/2/2 (w/w/w). The sensing structure comprises a silicon substrate, a SiO2 layer, and interdigitated transducer (IDT) electrodes. The sensing film is deposited on the sensing structure via the drop-casting method. The sensing layers’ morphology and composition are investigated through Scanning Electron Microscopy (SEM) and RAMAN spectroscopy. The resistance of thin-film sensors based on ternary hybrids increased with exposure to a range of relative humidity (R.H.) levels, from 0% to 100%. The newly designed devices demonstrated a comparable response at room temperature to that of commercial capacitive R.H. sensors, boasting excellent linearity, swift response times, and heightened sensitivity. Notably, the studied sensors outperform others employing CNHox-based sensing layers in terms of sensitivity, as observed through manufacturing and testing processes. It elucidates the sensing mechanisms of each constituent within the ternary hybrid nanocomposites, delving into their chemical and physical properties, electronic characteristics, and affinity for water molecules. Various alternative sensing mechanisms are considered and discussed, including the reduction in holes within CNHox upon interaction with water molecules, proton conduction, and PVP swelling.

Calcium hydroxide nanoparticles synthesized with medicinal plants extract as surface coating for titanium alloy bone implants using a simple method: Characterization and biomechanical evaluation

Advanced techniques have been developed to enhance the bioactivity and efficacy of biomedical titanium implants by modifying their surfaces. One such approach involves coating the titanium surface with biomaterials at the nanoscale level. In recent times, medicinal plant extracts have generated attention for nanoparticle synthesis due to their advantageous biomedical properties. Greenly synthesized carob-mediated calcium hydroxide nanoparticles exhibited promising results concerning both anti-inflammatory and osteogenic potentials during in vitro investigations. This study aimed to deposit these nanoparticles onto titanium-alloy bone implants through modifications to the established eco-friendly drop-casting method, characterize the surface, and biomechanically test it on rabbit tibias using torque removal analysis. Surface characterization utilizing scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction analysis successfully coated titanium implants with this material. A biomechanical study conducted on New Zealand rabbits revealed significantly higher peak torque removal values of the coated implants compared to uncoated implants (p < 0.01), suggesting enhanced osseointegration. The drop-casting method employed in this study is a straightforward, cost-efficient, and simple technique for coating various biomaterials onto titanium surfaces. This research lays the groundwork for further exploration of the potential benefits of using calcium hydroxide nanoparticles as titanium bone implant coatings, including their impact on bone healing, bactericidal capabilities, hemostatic potentials, and cellular activities.

CARBON NANOHORNS – BASED NANOCOMPOSITES AS SENSING LAYERS FOR ROOM TEMPERATURE RESISTIVE OXYGEN SENSING: PRELIMINARY RESULTS

This paper presents the oxygen sensing response of a resistive sensor employing sensing layers based on a binary matrix nanocomposite such as carbon nanohorns/polyvinylpyrrolidone and oxidized carbon nanohorns/polyvinylpyrrolidone, both at 9/1 w/w/ mass ratio. The sensing structure comprises a silicon substrate, a SiO2 layer, and interdigitated transducers (IDT) electrodes, on which the sensing layer is deposited via the drop-casting method. The thin film's morphology and composition are examined through scanning electron microscopy (SEM) and RAMAN spectroscopy. The oxygen sensing capability of each carbon nanohorns composite-based sensing layer was analyzed by applying a current between the two electrodes and measuring the voltage difference when varying the O2 from 0% to 100% in dry nitrogen. Experiments reveal that in the case of pristine carbon nanohorns / PVP matrix nanocomposite, the resistance increases. In contrast, in the case of oxidized carbon nanohorns, the resistance of the sensitive layer decreases with increasing oxygen concentration. The results are explained by considering the differences from structural and electrical points of view between the two types of nanocarbonic materials. Moreover, previous resistive RH sensing measurements in humid air and humid nitrogen using oxidized carbon nanohorns as sensing elements proved helpful in better understanding and discriminating between the chemisorption/physisorption of oxygen molecules at carboxyl functional sites and graphitic carbon sites.

Enzyme Immobilization by Inkjet Printing on Reagentless Biosensors for Electrochemical Phosphate Detection.

Enzyme-based biosensors commonly utilize the drop-casting method for their surface modification. However, the drawbacks of this technique, such as low reproducibility, coffee ring effects, and challenges in mass production, hinder its application. To overcome these limitations, we propose a novel surface functionalization strategy of enzyme crosslinking via inkjet printing for reagentless enzyme-based biosensors. This method includes printing three functional layers onto a screen-printed electrode: the enzyme layer, crosslinking layer, and protective layer. Nanomaterials and substrates are preloaded together during our inkjet printing. Inkjet-printed electrodes feature a uniform enzyme deposition, ensuring high reproducibility and superior electrochemical performance compared to traditional drop-casted ones. The resultant biosensors display high sensitivity, as well as a broad linear response in the physiological range of the serum phosphate. This enzyme crosslinking method has the potential to extend into various enzyme-based biosensors through altering functional layer components.

Development of Anti-TNT@Cu-BTC MOF thin film using drop caste method for trinitrotoluene (TNT) sensing

Antibody functionalised Cu-BTC MOF thin film was prepared using drop-casting method on indium tin oxide (ITO) coated glass substrate for trinitrotoluene (TNT) sensing under certain experimental conditions. Initially, APTES functionalization on ITO substrate using EDC-NHS chemistry was carried out, after which biofunctionalization of Anti-TNT on Cu-BTC MOF (1,3,5-tricarboxylic acid as an organic linker and copper ions as metal) thin film was carried out. Each step of sensor fabrication was characterised by the X-ray diffraction, microscopic and spectroscopic techniques. The interaction of one layer with another is confirmed with the help of FTIR and EDX. ITO substrate modification increases resistance at each stage from 1.29 to 3.3 KΩ. This modified substrate used as a working electrode during the sensing experiment. Afterward, response cum detection of 2,4,6-trinitrotoluene (TNT) in the 0.1 ppm to 0.6 ppm range has been noted by impedance method using three electrode systems of an electrochemical workstation. Host-guest interaction cum mechanism between TNT antibody functionalised APTES@Cu-BTC and TNT analyte has been observed which origins change in their resistance/impedance. The variation in resistance is directly proportional to the concentrations, exhibiting a strong linear relationship with 0.9702 value for R2. We find out that the presence of TNT antibody increases the specificity of TNT sensing and minimizes cross-reactivity with unknown/other interfering compounds. The concentration–response graph shows a 0.04 ppm limit of detection at room temperature.

Improvement in stability and exploring the photovoltaic properties of CsPbI2Br thin films for perovskite solar cells

The phase stability and quality of CsPbI2Br perovskite film directly determines the performance of perovskite solar cells (PSCs). However, there is a lack of research on phase stability of perovskite films of PSCs. Here, by simply controlling precursors with specified ratios and solvents, the phase stability, charge transfer resistance and electron lifetime improve significantly which is useful for high performance in perovskite solar cells. Besides this, the information about trap centres by a novel technique Charge Deep Level Transient Spectroscopy (Q-DLTS) also helps to improve efficiency of perovskite solar cells. In this work, CsPbI2Br perovskite thin films have been synthesized using simple solution processing method, by varying CsBr and PbI2 precursors with specified ratios of 1.05 M:1 M and 1.10 M:1 M in Dimethysulfoxide (DMSO) and Dimethyl formamide (DMF). The CsPbI2Br film with ratio of 1.05:1 has more phase stability in ambient air at room temperature than that of 1.10:1. Drop casting method was adopted for thin films preparation and structurally cubic phase of perovskite films obtained by X-ray diffraction (XRD). Scanning electron microscope (SEM) showed more homogeneity on the surface of the sample with ratio 1.05:1 and energy dispersive x-ray spectroscopy (EDX) confirmed the presence of same amounts in chemical composition. Fourier transform infrared spectroscopy (FTIR) transmittance spectra showed that main peak is generally observed because of stretching vibrations of lead-iodide ions. In UV–visible (UV-Vis) little effect was observed on the energy band gaps i.e. 1.93 eV for 1.05 M:1 M and 1.96 eV for 1.10 M:1 M. The electrochemical impedance spectroscopy (EIS) measurements were performed for electronic charges accumulation on the surface of the films which showed semi-circles Nyquist plots and frequency dependent Bode plots were used to find electron lifetime. The charge transfer resistance (Rct) decreased from 52Ω to 45Ω and electron life time were approximately equal to 0.10 s and 0.09 s for the ratio of 1.10:1 and 1.05:1. I-V measurements showed an Ohmic contact formation providing insights into defect concentrations with a linear response to applied bias. Recombination lifetimes were investigated using transient photovoltage (TPV) at various biases, no correlation between the applied bias and recombination lifetime was found. Q-DLTS indicated presence of 3 trap centers for the charge carriers which were actively responsible for degradation of the perovskite material, these traps serve as recombination centres that reduce the overall power conversion efficiency (PCE) of solar cells. Photoluminescence spectroscopy (PL) analysis was done to verify the energy bandgap value which was found similar in comparison to UV–VIS.

Use of Ball Drop Casting and Surface Modification for the Development of Amine-Functionalized Silica Aerogel Globules for Dynamic and Efficient Direct Air Capture.

Amine-functionalized silica aerogel globules (AFSAGs) were first synthesized via a simple ball drop casting method followed by amine grafting. The effect of grafting time on the structure and CO2 adsorption performance of the AFSAGs was investigated. The CO2 adsorption performance was comprehensively studied by breakthrough curves, adsorption capacity and rates, surface amine loading and density, amine efficiency, adsorption halftime, and cyclic stability. The results demonstrate that prolonging the grafting time does not lead to a significant increase in surface amine content owing to pore space blockage by superabundant amine groups. The CO2 adsorption performance shows obvious dependence on surface amine density, determined by both the surface amine content and specific surface area, and working temperature. AFSAGs with a grafting time of 24 h (AFSAG24) with a moderate surface amine density have optimal CO2 adsorption capacities, which are 1.78 and 2.14 mmol/g at 25 °C with dry and humid 400 ppm CO2, respectively. The amine efficiency of AFSAG24 with low CO2 concentrations, 0.38-0.63 with dry 400 ppm-1% CO2, is the highest among the reported amine-functionalized adsorbents. After estimation with different diffusion models, the CO2 adsorption process of AFSAG24 is governed by film diffusion and intraparticle diffusion. In the range of 1-4 mm, the ball size does not affect the CO2 adsorption capacity of AFSAG24 obviously. AFSAG24 offers significant advantages for practical direct air capture compared with its state-of-the-art counterparts, such as high dynamic adsorption capacity and amine efficiency, excellent stability, and outstanding adaptation to the environment.

Fabrication and Characterization of an Electrochemical Platform for Formaldehyde Oxidation, Based on Glassy Carbon Modified with Multi-Walled Carbon Nanotubes and Electrochemically Generated Palladium Nanoparticles.

This study outlines the fabrication process of an electrochemical platform utilizing glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes (MWCNTs) and palladium nanoparticles (PdNPs). The MWCNTs were applied on the GCE surface using the drop-casting method and PdNPs were produced electrochemically by a potentiostatic method employing various programmed charges from an ammonium tetrachloropalladate(II) solution. The resulting GCEs modified with MWCNTs and PdNPs underwent comprehensive characterization for topographical and morphological attributes, utilizing atomic force microscopy and scanning electron microscopy along with energy-dispersive X-ray spectrometry. Electrochemical assessment of the GCE/MWCNTs/PdNPs involved cyclic voltammetry (CV) and electrochemical impedance spectroscopy conducted in perchloric acid solution. The findings revealed even dispersion of PdNPs, and depending on the electrodeposition parameters, PdNPs were produced within four size ranges, i.e., 10-30 nm, 20-40 nm, 50-60 nm, and 70-90 nm. Additionally, the electrocatalytic activity toward formaldehyde oxidation was assessed through CV. It was observed that an increase in the size of the PdNPs corresponded to enhanced catalytic activity in the formaldehyde oxidation reaction on the GCE/MWCNTs/PdNPs. Furthermore, satisfactory long-term stability over a period of 42 days was noticed for the GCE/MWCNTs/PDNPs(100) material which demonstrated the best electrocatalytic properties in the electrooxidation reaction of formaldehyde.

PRODUCTION OF CuO/ZrO2 NANOCOMPOSITES IN POWDER AND FIBER FORMS

CuO/ZrO2 composite systems were synthesized in two different ways and comprehensively characterized with X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR), scanning electron microscopy(SEM), transmission electron microscopy(TEM), and energy dispersive X-ray spectroscopy(EDX). These metal oxide samples were prepared by hydrothermal synthesis and electrospinning process. In these methods, the same metal salts were used as precursors. Separately produced ZrO2 nanoparticles(NPs) and CuO particles have spherical and cube-like shapes, and both morphologies have monoclinic structures. However, ZrO2 and CuO particles do not have uniform diameters, and the average size of these particles ranges between 6–17 and 215–847 nm, respectively. Moreover, CuO/ZrO2 nanocomposite particles(NCPs) were synthesized using a facile and one-pot hydrothermal technique. They have uniform, spherical, and monoclinic structures with a 15nm average diameter. Furthermore, ZrO2 fibers were produced with the electrospinning process as highly crystalline structures after annealing, with a 230 nm average fiber diameter. In addition, ZrO2 fibers were doped with hydrothermally synthesized CuO particles with a drop-casting method for the first time. This study clearly shows that particle-fiber structure allows the development of the efficiency of p-type counterparts by using only 0.5-1.5wt.% n-type. With these results, two methods can be used to produce heterostructure CuO/ZrO2 composite particles/fibers and as potential for photocatalytic degradation.

Semiconducting 2D Copper(I) Iodide Coordination Polymer as a Potential Chemiresistive Sensor for Methanol.

The development of a cost-effective, ultra-selective, and room temperature gas sensor is theneed of an hour, owing to the rapid industrialization. Here, a new 2D semiconducting Cu(I) coordination polymer (CP) with 1,4-di(1H-1,2,4-triazol-1-yl)benzene (1,4-TzB) ligand is reported. The CP1 consists of a Cu2I2 secondary building unit bridged by 1,4-TzB, and has high stability as well as semiconducting properties. The chemiresistive sensor, developed by a facile drop-casting method derived from CP1, demonstrates a response value of 66.7 at 100ppm on methanol exposure, accompanied by swift transient (response and recovery time 17.5 and 34.2s, respectively) behavior. In addition, the developed sensor displays ultra-high selectivity toward methanol over other volatile organic compounds , boasting LOD and LOQ values of 1.22 and 4.02 ppb, respectively. The CP is found to be a state-of-the-art chemiresistive sensor with ultra-high sensitivity and selectivity toward methanol at room temperature.

Tailoring Silicon Composite Anodes with Li+-Containing Organic Ionic Plastic Crystals for Solid-State Batteries

Silicon is one of the highest-capacity anode active materials and, therefore, its use in solid-state batteries (SSBs) is expected to provide both high energy density and safety. Although the creation of solid-state Si electrodes via a scalable method is important from the perspective of battery production, the effect of electrode-preparation methods on electrochemical performance of electrodes with Li+-containing organic ionic plastic crystals (OIPCs) as solid electrolytes has yet to be investigated. Here, we prepared various Si−OIPC composite electrodes using four different methods and measured their electrochemical performance to decipher the method−structure−property relationship for high-performing SSBs. Si−OIPC composite electrodes containing 50 mol% LiFSI in N-ethyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide ([C2mpyr][FSI]) showed the highest initial Coulombic efficiency and cyclability. Three out of the four methods provided the Si−Li0.50[C2mpyr]0.50[FSI] electrodes with relatively large capacity retentions that were close to that of the Si electrode in a liquid electrolyte solution. Elemental analysis of electrode cross-sections showed homogeneous distribution of Li0.50[C2mpyr]0.50[FSI], except for those prepared by the drop-cast method, suggesting that well-designed methods can establish the long-range ion-conduction network in the electrode necessary to improve the electrochemical stability of Si during cycling. This study clarifies the importance of the OIPC-incorporation method in fabricating highly functional OIPC-based electrodes for SSBs.

Comparative Study of Electrochromic Properties of Polyaniline–Polyacid Layers Prepared by Spray-Coating and Drop-Casting Methods with Adding Carbon Nanotubes

Comparative Study of Electrochromic Properties of Polyaniline–Polyacid Layers Prepared by Spray-Coating and Drop-Casting Methods with Adding Carbon Nanotubes

The synergistic impact of multi walled carbon nanotubes on microstructural, morphological, and optical properties of polyaniline films

AbstractNanocomposite of polyaniline (PANI) and multi walled carbon nanotube (MWCNT) was synthesised by ex‐situ solution mixing process in the N‐Methyl‐2‐Pyrrolidinone (NMP) solvent medium by varying the concentration of MWCNT in the PANI matrix. PANI‐MWCNT composite films were prepared by the drop casting method. The morphology, structure and chemical composition of PANI and PANI‐MWCNT nanocomposites were characterised by scanning electron microscopy (SEM), transmission electron microscopy (TEM), x‐ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT‐IR) spectra. The experimental findings suggested a favourable synergy between PANI and MWCNTs. PANI‐MWCNT nanocomposite formed as randomly oriented nanofibrous clusters was confirmed, and the bandgap of the composites was found to be gradually decreased with the increase in concentration of MWCNT in the PANI matrix. The calculation of crystallinity index, crystallite size, average d‐spacing, dislocation density, lattice strain, and inter chain separation of the samples were conducted by XRD analysis. When the MWCNT concentration increased from 0.05 % w/v to 0.5 % w/v, a rise in the degree of crystallinity from 3.39 % to 52.46 %, dislocation density from 0.03315×10−3(nm−2)to 0.07133×10−3 (nm−2) and lattice strain from 8.6821×10−3 to 12.9843×10−3, accompanied by a reduction in both crystallite size and inter‐chain separation were observed .The microcrystalline behaviour and crystalline orientation of the PANI‐MWCNT composites were correlated with the bandgap studies. The composite formation improved the thermal stability of PANI. The co‐relation between the crystallinity parameters and fine tuning of optical bandgap and the control over the defect levels were done in this study. This synergy suggests that these composites are suitable candidates for linear and nonlinear optical (NLO) applications.

Development of sensitive electrochemical sensor Ni@CuO/rGO/PtE for the determination of 4-Nitrophenol: An electroanalytical approach for pollution control

Para nitrophenol, generally known as 4-nitrophenol (4-NP), is a well-known organic pollutant that is being broadly discharged into the environment and poses several health threats to humans. For the sensitive and selective screening of 4-NP, a new electrochemical sensor based on Ni@CuO/rGO/PtE has been developed. The XRD analysis revealed excellent crystalline structure with an average size of 47.3 nm for Ni@CuO/rGO nanocomposite. SEM and HR-TEM characterization evaluated the successful incorporation of Ni and CuO into the GO sheets. The EDX analysis confirmed the prepared nanocomposite's exceptional purity and percent elemental composition. The prepared material was casted on the surface of bare PtE via the drop-casting method, which resulted in the uniform deposition of Ni@CuO/rGO over the PtE's surface. The fabricated sensor Ni@CuO/rGO/PtE manifested excellent response for 4-NP under optimized conditions, e.g., scan rate 110 mV/s, PBS electrolyte acidic pH -5, and under potential window between (−0.3 to −1.2 V). A broad linear concentration range was optimized from 0.09 to 105 μM to get a linear calibration curve of 4-NP. The LOD and LOQ of the proposed method were calculated as 0.0054 μM and 0.018 μM, which is almost lower than the reported sensor for 4-NP. The analytical applicability of Ni@CuO/rGO/PtE was tested in tap water and river water samples. The fabricated sensor exhibited acceptable recoveries for 4-NP in water samples, highlighting the proposed sensor's good reliability in real samples.

A NiO-nanostructure-based electrochemical sensor functionalized with supramolecular structures for the ultra-sensitive detection of the endocrine disruptor bisphenol S in an aquatic environment.

Herein, NiO nanoparticles (NPs) functionalized with a para-hexanitrocalix[6]arene derivative (p-HNC6/NiO) were synthesized by using a facile method and applied as a selective electrochemical sensor for the determination of bisphenol S (BPS) in real samples. Moreover, the functional interactions, phase purities, surface morphologies and elemental compositions of the synthesized p-HNC6/NiO NPs were investigated via advanced analytical tools, such as Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). Additionally, the synthesized p-HNC6/NiO NPs were cast on the surface of a bare glassy carbon electrode (GCE) via a drop casting method, which resulted in uniform deposition of p-HNC6/NiO/GCE over the surface of the GCE. Additionally, the developed p-HNC6/NiO/GCE sensor demonstrated an outstanding electrochemical response to BPS under optimized conditions, including a supporting electrolyte, a Briton-Robinson buffer electrolyte at pH 4, a scan rate of 110 mV s-1 and a potential window of between -0.2 and 1.0 V. The wide linear dynamic range was optimized to 0.8-70 μM to obtain a brilliant linear calibration curve for BPS. The limit of detection (LOD) and limit of quantification (LOQ) of the developed sensor were estimated to be 0.0059 and 0.019 μM, respectively, which are lower than those of reported sensors for BPS. The feasibility of the developed method was successfully assessed by analyzing the content of BPS in waste water samples, and good recoveries were achieved.

A high-performance flexible humidity sensor based on a TiO2-MWCNT nanocomposite for human healthcare applications.

The present work shows the improved humidity sensing characteristics of TiO2 nanoparticles in the form of a nanocomposite with multiwalled carbon nanotubes (MWCNTs) prepared by a hydration-dehydration method. The structural and morphological characterizations of TiO2-MWCNTs confirm the nanocomposite formation without any other impurities and with an improved surface area. The pure TiO2 and nanocomposite films are deposited on IDE coated flexible poly-ethylene terephthalate (PET) substrates by a drop casting method. The nanocomposite shows improved sensitivity (1246.2 MΩ/%RH) and an ultrafast response/recovery time (2 s/1 s) with a minimal hysteresis of 0.27%RH. Further, the flexible nanocomposite sensor is tested for human healthcare applications including respiratory monitoring, apnea like situations, and skin moisture detection. The sensor can distinguish different breath patterns like normal, fast, deep and apnea like situations significantly. Skin moisture detection can also be performed using the nanocomposite sensor in a non-invasive manner. Overall, this study represents an environmentally friendly, easy to fabricate, flexible TiO2-MWCNT nanocomposite based improved humidity sensor for application in human healthcare and wearable devices.

Influence of various solvents in extraction of natural pigments from Annona atemoya and Physalis peruviana as photosensitizers for dye-sensitized solar cells

Herein, we investigate the effect of various solvents on the extraction of natural dyes from two different fruit skins, namely Annona atemoya (Atemoya) and Physalis peruviana (Physalis), as photosensitizers for dye-sensitized solar cells (DSSCs). The functional groups of the extracted dye pigmentation were confirmed using Fourier-transform infrared spectroscopy (FTIR) to verify the presence of anthocyanin radicals. To fabricate the DSSCs, semiconducting TiO2 nanoparticles were deposited on FTO glass as a photoanode (using the spin-coating method), and platinum was also deposited on FTO glass as a photocathode (using the drop-casting method). Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were performed to verify the surface roughness and morphologies of the TiO2 photoanode and Pt photocathode. The photoelectric performance results of the fabricated DSSCs were examined and revealed the influence of various solvents on the extraction of Annona atemoya and Physalis peruviana dyes. The extraction of Annona atemoya and Physalis peruviana dyes in methanol solvent showed higher energy conversion efficiency of 2.02 % and 0.31 %, respectively, compared to other solvent extractions. In general, this work demonstrates that constructing solar cells from natural dyes at a reduced cost is a viable and sustainable alternative to traditional silicon cells.

Surface modification of medical grade biomaterials by using a low-temperature-processed dual functional Ag-TiO2 coating for preventing biofilm formation.

Biofilm development in medical devices is considered the major virulence component that leads to increased mortality and morbidity among patients. Removing a biofilm once formed is challenging and frequently results in persistent infections. Many current antibiofilm coating strategies involve harsh conditions causing damage to the surface of the medical devices. To address the issue of bacterial attachment in medical devices, we propose a novel antibacterial surface modification approach. In this paper, we developed a novel low-temperature based solution-processed approach to deposit silver nanoparticles (Ag NPs) inside a titanium oxide (TiO2) matrix to obtain a Ag-TiO2 nanoparticle coating. The low temperature (120 °C)-based UV annealed drop cast method is novel and ensures no surface damage to the medical devices. Various medical-grade biomaterials were then coated using Ag-TiO2 to modify the surface of the materials. Several studies were performed to observe the antibacterial and antibiofilm properties of Ag-TiO2-coated medical devices and biomaterials. Moreover, the Ag-TiO2 NPs did not show any skin irritation in rats and showed biocompatibility in the chicken egg model. This study indicates that Ag-TiO2 coating has promising potential for healthcare applications to combat microbial infection and biofilm formation.

Enhancing saturable absorption in a Au-decorated MoS2/PEDOT:PSS nanocomposite through plasmon resonance and Pauli blocking.

We have effectively demonstrated a technique for substantial alteration of the nonlinear saturable absorption (SA) properties in nanocomposite films (NCF) composed of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT:PSS) and molybdenum disulfide (MoS2) decorated with gold nanoparticles (AuNPs). This control is achieved by adjusting the AuNP concentration on the MoS2 surface and varying the input pulse energy of the laser. The simple drop-casting method is used to create the nanocomposite films (NCFs) on a glass substrate with different amounts of Au-decorated MoS2. The Kramers-Kronig equations are employed for determining the refractive index and extinction coefficient values of the resulting NCFs. Nonlinear investigations reveal that adding Au-decorated MoS2 to pure PEDOT:PSS alters its optical nonlinearity. Surface plasmon resonance and Pauli blocking have been observed in Au-decorated MoS2/PEDOT:PSS NCFs. This increases NCF's saturable absorption. An open aperture Z-scan method is utilized to study nonlinear optics, with excitation achieved using a nanosecond (ns) pulsed laser operating at a 532 nm wavelength. The findings reveal the noteworthy saturable absorption characteristics of the NCFs.