Simple Wet Process Research Articles

The significant role of Z-scheme band alignment at the heterojunction for the enhanced photocatalytic H2 production in TiO2/BiNbO4/rGO nanocomposite

An efficient ternary TiO2/BiNbO4/rGO nanocomposite was prepared by a simple wet impregnation process. PXRD confirmed the tetragonal and orthorhombic crystalline natures of titanium dioxide (TiO2) and bismuth niobate (BiNbO4) respectively. The loading of BiNbO4 and reduced graphene oxide (rGO) shifted the light absorption of TiO2 to a longer wavelength from 400 to 430 nm. The suitable conduction band position of BiNbO4 facilitated a favourable band alignment to suppress the electron/hole (e−/h+) recombination in TiO2 via the Z scheme mechanism at the heterojunction. The excited electrons at the CB of TiO2 were easily transported via the fast electron accepting and conducting rGO matrix for the surface redox reactions with the improved charge transfer efficiency, which was confirmed by EIS and PL studies respectively. BiNbO4 and rGO synergistically improved the specific surface area and solar light absorption. EPR analysis confirmed the presence of increased oxygen vacancies at the heterojunction. Hence, the ternary TiO2/BiNbO4/rGO nanocomposite demonstrated an enhanced hydrogen evolution (8910 μ mol h−1 gcat−1) than bare TiO2 (4820 μ mol h−1 gcat−1), bare BiNbO4 (950 μ mol h−1 gcat−1) and TiO2/BiNbO4 (6730 μ mol h−1 gcat−1) under direct solar light. The optimum of 1 wt % BiNbO4 and rGO loaded TiO2 nanocomposite produced twice the H2 production than the bare TiO2. This also further confirms that rGO played a major role during the photocatalytic process by highlighting the potential of metal oxides combined with carbon material as an efficient photocatalyst which prominently enhances the H2 evolution.

Cellulose Fiber with Enhanced Mechanical Properties: The Role of Co-Solvents in Gel-like NMMO System.

Cellulose has garnered attention in the textile industry, but it exhibits limitations in applications that require high strength and modulus. In this study, regenerated cellulose fiber with enhanced mechanical properties was fabricated from a gel-like N-methylmorpholine N-oxide (NMMO)-cellulose solution by modulating the intermolecular interaction and conformation of the cellulose chains. To control the interaction, two types of co-solvents (dimethyl acetamide (DMAc) and dimethyl formamide (DMF)) were added to the cellulose solutions at varying concentrations (10, 20, and 30 wt%). Rheological analysis showed that the co-solvents reduced the solution viscosity by weakening intermolecular interactions. The calculated distance parameter (Ra) in Hansen space confirmed that the co-solvent disrupted intermolecular hydrogen bonding within cellulose chains. The solutions were spun into fiber via a simple wet spinning process and were characterized by X-ray diffraction (XRD) and universal testing machine (UTM). The addition of co-solvent led to an increased crystallinity index (C.I.) owing to the extended cellulose chains. The modulus of the resulting fiber was increased when the co-solvent concentration was 10 wt%, regardless of the co-solvent type. This study demonstrates the potential for enhancing the mechanical properties of cellulose-based products by modulating the conformation and interaction of cellulose chains through the addition of co-solvent.

3D cellulose network confining MXene/MnO2 enables flexible wet spinning microfibers for high-performance fiber-shaped Zn-ion capacitors

Fiber-shaped Zn-ion capacitors (FSZICs) have shown great potential in wearable electronics due to their long cycle life, high energy density, and good flexibility. Nevertheless, it is still a critical challenge to develop a conductive fiber with long size and high mechanical properties as the FSZIC cathode using sustainable and low-cost materials. Herein, regenerated cellulose (RC) -based conductive microfibers are prepared by a simple, continuous, and scalable wet spinning process. The 3D nanoporous networks of RC caused by physical self-cross-linking allow MXene and MnO2 to be uniformly and firmly embedded. The rapid extrusion and limited drying result in the highly aligned structure of the fibers, endowing the hybrid fiber with an ultra-high tensile strength (145.83 Mpa) and Young's modulus (1672.11 Mpa). MXene/MnO2-RC-based FSZIC demonstrates a high specific capacitance of 110.01 mF cm−3, an energy density of 22.0 mWh cm−3 at 0.57 A cm−3 and excellent cycling stability with 90.5 % capacity retention after 5000 cycles. This work would lead to a great potential of cellulose for application in next-generation green and wearable electronics.

Novel Fe2O3/Bi2O3/CeO2 heterojunction photocatalyst for wastewater treatment: Characterization, photocatalytic performance and mechanism study

A novel ternary Fe2O3/Bi2O3/CeO2 (FeB/CeO2) heterojunction nanocomposite with different Fe2O3/Bi2O3 amounts on CeO2 (5, 10, 20, 30 and 40 wt%) was synthesized through a simple wet impregnation process. The properties of the synthesized nanocomposite were validated thorough XPS, XRD, FE-SEM, TEM, and EDS-Mapping analyses. This photocatalyst exhibited exceptional efficiency in the of Tetracycline’s (TC) photodegradation in comparison to individual Fe2O3, Bi2O3, and CeO2. The effect of Fe2O3/Bi2O3 loading on CeO2 and the influence of operational factors on TC decomposition including photocatalyst dosage (0.05–0.2 g/L), TC concentration (10–40 mg/L), and pH (1–11) were examined with the optimal conditions yielding an experimental degradation efficiency of 99.35 %. Moreover, scavenger tests showed that O2− and OH radicals served as the main oxidative radical species. The study further delved into proposing potential degradation pathways of TC in accordance with liquid chromatography tandem-mass spectrometry analysis. Notably, the stability of the synthesized photocatalyst was assessed through five degradation cycles, affirming its sustained effectiveness.

Thermo-Compression Sinter-Bonding in Air Using Cu Formate/Cu Particles Mixed During Reduction of Cu<sub>2</sub>O

A Cu-based paste containing Cu formate and Cu particles was prepared for the compressionassisted sinter-bonding of Cu-finished wide-bandgap power devices onto a Cu-finished substrate at a relatively low bonding temperature of 250 oC in air. A mixture of Cu formate and Cu particles was designed to mitigate the tremendous volume shrinkage during reduction of Cu formate, which approaches approximately 90%, and could be a significant obstacle in the formation of a high-density bond-line. The mixture was spontaneously formed during the 15-min reduction of the initial Cu<sub>2</sub>O particles by a simple wet process using formic acid. In the bonding, pure Cu generated in situ from the Cu formate at a temperature exceeding 200 °C exhibited significant sinterability, and the generated hydrogen reduced oxide layers on the Cu finishes. Furthermore, the mixed particles resulted in low volume shrinkage in the bond-line during bonding, compared to the use of Cu formate particles alone. Consequently, a robust die shear strength of 22.2 MPa was achieved by sinterbonding for even 10 min at low temperature and the compression of 10 MPa, even though Cu oxide shells were formed in the bond-line because of the long sintering in air. The simple wet process provided an efficient preparation of an effective filler system before the paste formulation for the sinter-bonding.

Off-Grid Electrogenerated Chemiluminescence with Customized p-i-n Photodiodes.

Electrochemiluminescence (ECL) is the generation of light induced by an electrochemical reaction, driven by electricity. Here, an all-optical ECL (AO-ECL) system is developped, which triggers ECL by the illumination of electrically autonomous "integrated" photoelectrochemical devices immersed in the electrolyte. Because these systems are made using small and cheap devices, they can be easily prepared and readily used by any laboratories. They are based on commercially available p-i-n Si photodiodes (≈1€unit-1), coupled with well-established ECL-active and catalytic materials, directly coated onto the component leads by simple and fast wet processes. Here, a Pt coating (known for its high activity for reduction reactions) and carbon paint (known for its optimal ECL emission properties) are deposited at cathode and anode leads, respectively. In addition to its optimized light absorption properties, using the commercial p-i-n Si photodiode eliminates the need for a complicated manufacturing process. It is shown that the device can emit AO-ECL by illumination with polychromatic (simulated sunlight) or monochromatic (near IR) light sources to produce visible photons (425nm) that can be easily observed by the naked eye or recorded with a smartphone camera. These low-cost off-grid AO-ECL devices open broad opportunities for remote photodetection and portable bioanalytical tools.

Electrochemically exfoliated graphene oxide enhanced hybrid fibers with high rate performance for fibrous supercapacitors

In this study, a composite graphene fiber was created using electrochemically exfoliated graphene oxide (EGO) and chemically oxidized graphene oxide (GO) through a simple wet spinning process. The incorporation of EGO sheets in the fiber forms a highly conductive network, significantly enhancing its conductivity. The optimized EGO/GO fiber exhibits both high areal capacitance (532 mF cm−2) and volumetric capacitance (103 F cm−3). Moreover, the EGO/GO composite fiber demonstrates superior capacitance retention and increased fiber length compared to the GO fiber. A solid-state device was also constructed by the optimized EGO/GO fiber using PVA/H2SO4 gel electrolyte which demonstrates excellent flexibility. And the as prepared solid-state fiber shaped supercapacitor demonstrates an areal capacitance of 246 mF cm−2 at a current density of 0.69 mA cm−2, while maintains 185 mF cm−2 at a current density of 34.7 mA cm−2 showcasing excellent rate performance.

G-C3N4/WO3(H2O)0.33 nanostructured electrode for hybrid asymmetric-supercapacitor

The demand for high-energy storage supercapacitors with appropriate designs has been emerging in recent times. Aimed at enhancing the electrochemical storage performance of supercapacitors, g-C3N4/WO3(H2O)0.33 (GCN/WO) nanostructures have been prepared in a simple wet impregnation process by mixing the synthesized g-C3N4, and WO3(H2O)0.33 materials and their performances were compared systematically with their individual components. The successful formation of C3N4/WO3(H2O)0.33 nanostructure has been confirmed by the XRD, SEM, EDS, HR-TEM, HAADF and XPS spectroscopy analyses. The prepared GCN/WO nanostructures showed greater specific capacitance of 466.88C g−1 at 1.5 A g−1 than their counterparts (GCN 87.87C g−1 and WO 140.64C g−1) with remarkable cyclic stability of 98.6% over 10000 cycles. Notably, the fabricated hybrid asymmetric supercapacitor devices (HASDs) exhibited ultrahigh power density of 255.23 W kg−1 at energy density of 10.07 Wh kg−1. The enhanced electrochemical capacitor characteristics of GCN/WO nanostructures could be attributed to the positive synergistic effect of GCN and WO. Thus, the strategy utilizing this synergistic effect between GCN and WO in a simple impregnation process is a viable alternative to fabricate the high capacitance electrodes for application in supercapacitors.

Next-generation ecofriendly MR fluid: Hybrid GO/ Fe2O3 encapsulated carbonyl iron microparticles with improved magnetorheological, tribological, and corrosion resistance properties

In this study, magnetorheological fluid (MRF) was developed using hybrid core-shell particles. The core of these particles consists of carbonyl iron (CI), while the shell is composed of graphene oxide (GO) and iron oxide (Fe2O3) nanocomposite particles. The hybrid nanocomposite and core-shell particles were synthesized through a simple wet stirring process. A blended biocompatible oil comprising 90% rice bran oil and 10% silicone oil was employed as the continuous phase to ensure environmental and economic feasibility. Various characterization techniques were employed to examine the surface, structural, and magnetic properties of the hybrid core-shell particles. Magnetorheological (MR) measurements demonstrated that the incorporation of GO/Fe2O3 nanocomposite particles onto the CI particles (CIPs) significantly enhanced the shear stress and yield stress properties of the resulting MRF. This improvement can be ascribed to an increase in the magnetic saturation resulting from the encapsulation of GO-decorated Fe2O3 nanocomposite particles. The corrosion resistance and sedimentation properties were evaluated in this study, and the hybrid core-shell particles exhibited superior results compared to the bare CIPs. In terms of tribological performance, the hybrid core-shell particles exhibited significant improvement in friction and wear properties in comparison to the bare CIPs-based MRF and dry sliding condition. The significant reduction in coefficient of friction (COF) and wear might be attributed to the development of a lubricating protective layer consisting of bare CIPs and hybrid core-shell particles-based MR fluids (MRFs) at the contact interface. Consequently, this study offers an economical and effective approach for formulating MRFs with desirable rheological and tribological characteristics and corrosion inhibition properties, making them suitable for various environmental and industrial applications.

Ultrathin Al-doped SiO x passivating hole-selective contacts formed by a simple wet process

Ultrathin Al-doped Si oxide (SiO x ) layers were formed by a simple wet chemical treatment, and their hole-selective passivating contact and electrical properties were investigated. From the evaluated contact resistivity (ρ c) and saturation current density (J 0), carrier selectivity (S 10) was estimated to be 13.3. Moreover, in Si nitride (SiN y )/Al-doped SiO x stacks, negative values of fixed charge density (Q f) were obtained, despite a high positive Q f existing in the single SiN y layer. This result implies that Al-doped SiO x has high negative fixed charges and overcompensates the charge polarity in the stacks, which forms an inversion layer and accumulates holes on the Si surface. Furthermore, the negative fixed charges realize excellent carrier separation by the induced upward band bending. In addition, we proposed a novel device architecture named Al-induced charged oxide inversion layer solar cells and confirmed device operation in a simple device configuration.

Green synthesis of carbon dots from spent coffee grounds via ball-milling: Application in fluorescent chemosensors

Carbon dots (CDs) are nanoparticles that have gained widespread attention due to their unique properties including multicolored fluorescence, photochemical stability, and biocompatibility. However, the conventional approaches for the preparation of CDs typically require high energy input and toxic reagents. Herein, a sustainable, high throughput approach is reported for producing uniform CDs. Specifically, spent coffee grounds (SCGs) are used to produce coffee ground-derived carbon dots (CFCDs) via a simple wet ball-milling process. The versatility of our approach can be extended to the synthesis of heteroatom-doped CDs and the preparation of CDs from various SCG sources. Also, the functional groups of the CFCDs are manipulated by the addition of citric acids during the ball-milling process to produce carboxylic acid-functionalized carbon dots (CA-CFCDs). CA-CFCDs exhibit highly selective and sensitive detection of Fe3+ ions in aqueous solution via fluorescence quenching, and the relevant quenching mechanism is investigated. Finally, we demonstrate the fluorescent microgel sensor exhibiting a rapid, ratiometric fluorescence change upon the addition of Fe3+ ion by encapsulating the CA-CFCDs within the microgel matrix.

Silicon Photoelectrodes Prepared by Low-Cost Wet Methods for Solar Photoelectrocatalysis

ConspectusThe electrochemical conversion of sunlight by photoelectrochemical cells (PECs) is based on semiconductor electrodes that are interfaced with a liquid electrolyte. This approach is highly promising, first, because it can be employed for the generation of a chemical fuel (e.g., H2) to store solar energy that can be used on-demand to generate electricity when the sun is not available. Second, it can be seen as a concept reminiscent of photosynthesis, where CO2 is converted into a valuable feedstock by solar energy. Thus, photoelectrochemical cells are sometimes referred to as “artificial leaves”. Silicon, being the main semiconductor in the electronics and photovoltaic sector, is a prime candidate to be used as the light absorber and the substrate for building photoelectrochemical cells. However, Si alone has “poor-to-no photoelectrochemical performance”. This is caused by its weak electrocatalytic activity for cathodic reactions (namely, the hydrogen evolution reaction (HER), the CO2 reduction reaction (CDRR), and the N2 reduction reaction) and by its deactivation in the anodic regime, prohibiting its use for the oxygen evolution reaction (OER). This latter reaction is essential for supplying electrons to generate a solar fuel. Due to these problems, layers that both protect and are catalytically active are typically employed on Si photoelectrodes but require rather sophisticated manufacturing processes (e.g., atomic layer or electron beam deposition), which hinders research and innovation in this field. Nevertheless, our group and others have demonstrated that these layers are not always required and that highly active and stable Si-based photoelectrodes can be manufactured using simple wet processes, such as drop casting, electroless deposition, or aqueous electrodeposition. In this Account, we first introduce the topic and the possible structures that can be easily obtained starting from commercial Si wafers. Then, we discuss strategies that have been employed to manufacture photocathodes based on p-type Si. Among these, we describe Si photocathodes coated with metal, inorganic compounds such as metal sulfides, and more original constructs, such as those based on macromolecules composed of a catalytic Mo3S4 core and a polyoxometallate macrocycle. Also, we discuss the elaboration and the advantages of Si photocathodes obtained by grafting organometallic catalysts which are promising candidates for reaching excellent selectivity for the CDRR. Then, the manufacturing of photoanodes based on n-Si is reviewed with an emphasis on those prepared by electrodeposition of a transition metal such as Ni and Fe. The effect of the catalyst morphology, density, and Si structuration is discussed, and future developments are proposed.

Friction and wear properties of core-shell (CI is a core & GO is a shell) particles based magnetorheological fluid under steel on steel point contacts

This work is concerned with the experimental investigation of tribological and rheological properties of core–shell (carbonyl iron is the core and graphene oxide is the shell) particle-based MR fluid. Carbonyl iron (CI) particles were encapsulated with graphene oxide (GO) by a simple wet stirring process. The surface morphology, structural properties, and magnetic properties of graphene oxide encapsulated CI particles were analyzed by Field Emission Spectroscopy (FE-SEM), Raman Spectroscopy, and Vibrational Sample Magnetometer (VSM). The rheological properties of prepared samples were examined on a modular compact rheometer. The CI@GO particle-based MR fluid exhibited lower yield stress compared to bare CI particle-based MR fluid. Tribological tests of developed MR fluid were conducted on a universal tribometer with and without the presence of a magnetic field to ascertain the friction and wear behaviour. Experimental results revealed that the tribological properties are significantly improved by using CI@GO-based MR fluid in comparison to bare CI-based MR fluid and dry sliding conditions. Further, the wear analysis of worn surfaces was observed on FE-SEM, Energy-Dispersive X-ray Spectroscopy (EDS), and 3D-profilometer before and after each test. Three body abrasion wear mechanism was observed with some ploughing and groove formation.

Vacuum wetting of Ag/TA2 to develop a novel micron porous Ti with significant biocompatibility and antibacterial activity

· A simple approach to fabricate micron-scale porous Ti was developed. · A surface-layered porous structure dispersing with AgNPs was obtained on TA2. · Volatilization/sublimation of Ag in TA2 promotes forming the pores and AgNPs. · The porous Ti has excellent biocompatibility and bio-corrosion resistance. · The porous Ti has an excellent antibacterial activity. Porous Ti with low modulus, excellent bio-corrosion resistance, biocompatibility, and antibacterial activity is highly pursued as advanced implant materials. In this work, a new approach to prepare micron porous structures on the surface layer of a grade 2 commercially-pure Ti (TA2) was proposed, which utilized a simple vacuum wetting process of pure Ag on the surface of TA2. The microstructure, corrosion resistance, biocompatibility, mechanical properties, antibacterial ability, and formation mechanism of the as-fabricated porous Ti were studied. The results show that the pores (with average pore sizes of 0.5–5 μm) are distributed on the surface layer of the TA2 with a depth of ∼10 μm. In particular, a large number of silver nanoparticles (AgNPs) form which are dispersed on the porous structures. The formation mechanisms of the porous structures and AgNPs were elucidated, suggesting that the volatilization/sublimation of Ag in TA2 is crucial. The porous Ti possesses excellent bio-corrosion resistance, surface wettability, biocompatibility, antibacterial activity, and a relatively low elastic modulus of 40–55 GPa, which may have a promising future in the field of orthopedic implants. This work also provides a novel idea for the development of advanced porous Ti materials for orthopedic-related basic research and biomedical applications.

A surface plasmon resonance temperature sensor using TiO2 nanoparticles on hetero-core fiber optic structure with Au thin film

Abstract A surface plasmon resonance (SPR)-based temperature sensor was developed based on hetero-core structured fiber optics with multilayer films of titanium dioxide (TiO2) nanoparticles (NPs) and poly-L-lysine (PLL) formed by electrostatic interaction as a simple wet process on gold (Au) film onto a cylindrical cladding surface. We experimentally observed that the resonant wavelength shifted 135.6 nm toward a shorter wavelength for a temperature change from 100 °C to 300 °C. In light intensity-based measurement, the sensitivity of the transmitted loss change was 1.8 × 10−2 dB °C−1 at a wavelength of 700 nm when 19 layers of TiO2 NPs and PLL was annealed onto a 40 nm thick Au film, which improved by over 12 times higher sensitivity than in the conventional radiofrequency (RF) sputtering fabrication method. The proposed sensor successfully detected temperature changes with high sensitivity and linearity as well as simplified the fabrication process compared with the conventional RF sputtering fabrication method.

Effect of autoclaving as a pre-treatment in the wet reduction process for extracting fish oil from yellowfin tuna heads

Various studies have focused on extracting fish oil using a variety of methods, yet, the wet reduction process is the common industrial method as it is environmentally friendly. However, the use of autoclaving in extracting oils from fish or fish by-products are comparatively less. Therefore, this study was conducted to extract crude oils from the yellowfin tuna (Thunnus albacares) head, the lipids richest body part compared to processing offcuts like skin, viscera etc., by a simple wet reduction process using an autoclave at 121°C as the pre-treatment with different holding times (15, 30, and 45 min). The maximum extraction yield of 5.37±0.22 % was recorded at 30 min holding time of autoclave. No significant changes in peroxide value, moisture content and colour values were observed for the different autoclaving durations (P > 0.05). Conversely, acid value, p-anisidine value and total oxidation value (TOTOX) were increased significantly with a longer autoclaving duration of 45 min (P < 0.05). However, all peroxide values, p-anisidine value, TOTOX value were below the standard values stated by the World Health Organization (WHO) except the acid values which shows the need for refinery before any applications. Based on the spectra of Attenuated total reflectance - Fourier transform infrared (ATR-FTIR), autoclaving for a longer time resulted in lower intensity at wavenumbers around 3,012 - 3,013 and 1,741 - 1,744 cm−1 and shifting of bands to lower wavenumbers showing its effect on the structural changes of molecules in the oil. All extracted oils resulted in a high PUFA content than MUFA and SFA contents based on the fatty acid composition. The DHA (C22:6, n3) was the most prominent fatty acid in all the oil samples. However, PUFA content was reduced slightly by increasing the autoclaving duration at 45 min. Therefore, this study concludes autoclaving at 121°C for 30 minutes as the optimum pre-treatment conditions to extract fish oil from yellowfin tuna heads using the wet reduction process.

Construction of magnetically recoverable novel Z-scheme La(OH)3/α-MnO2/MnFe2O4 photocatalyst for organic dye degradation under UV–visible light illumination

Researchers have been fascinated to the field of photocatalysis by the creation of innovative composite photocatalysts to enhance the performance of the catalyst. The novel magnetically recoverable La(OH)3/α-MnO2/MnFe2O4 nanocomposite have been successfully prepared via a simple wet impregnation process. The as-synthesized photocatalysts were characterized by multiple analytical techniques. The photocatalytic performance of the as-prepared materials was examined based on Rhodamine B (Rh B) dye under UV–visible light illumination. The obtained Z-scheme magnetically recoverable La(OH)3/α-MnO2/MnFe2O4 nanocomposite exhibited remarkably photocatalytic activity (94.69%), 4.04 and 2.33 times higher than the La(OH)3 and α-MnO2/MnFe2O4 nanocomposite, respectively. The ferromagnetic behavior of MnFe2O4 nanoparticles (NPs) and the high light absorption capacity of α-MnO2 nanorods improve the photocatalytic performance of La(OH)3/α-MnO2/MnFe2O4 nanocomposite. La(OH)3/α-MnO2/MnFe2O4 nanocomposite was able to help ease the recovery by its ferromagnetic behavior. This enriched photocatalytic performance could be caused by the formation of Z-scheme junctions between La(OH)3 and α-MnO2/MnFe2O4 nanocomposite, which helps effectual charge separation and keeps a high redox potential. Magnetically recoverable La(OH)3/α-MnO2/MnFe2O4 nanocomposite offers potential for photocatalysis and has probable applications in the energy and environmental sectors.

Ultra-sensitive and fast optical detection of the spike protein of the SARS-CoV-2 using AgNPs/SiNWs nanohybrid based sensors

Severe acute respiratory syndrome SARS-CoV-2 virus led to notable challenges amongst researchers in view of development of new and fast detecting techniques. In this regard, surface-enhanced Raman spectroscopy (SERS) technique, providing a fingerprint characteristic for each material, would be an interesting approach. The current study encompasses the fabrication of a SERS sensor to study the SARS-CoV-2 S1 (RBD) spike protein of the SARS-CoV-2 virus family. The SERS sensor consists of a silicon nanowires (SiNWs) substrate decorated with plasmonic silver nanoparticles (AgNPs). Both SiNWs fabrication and AgNPs decoration were achieved by a relatively simple wet chemical processing method. The study deliberately projects the factors that influence the growth of silicon nanowires, uniform decoration of AgNPs onto the SiNWs matrix along with detection of Rhodamine-6G (R6G) to optimize the best conditions for enhanced sensing of the spike protein. Increasing the time period of etching process resulted in enhanced SiNWs’ length from 0.55 to 7.34 µm. Furthermore, the variation of the immersion time in the decoration process of AgNPs onto SiNWs ensued the optimum time period for the enhancement in the sensitivity of detection. Tremendous increase in sensitivity of R6G detection was perceived on SiNWs etched for 2 min (length=0.90 µm), followed by 30s of immersion time for their optimal decoration by AgNPs. These SiNWs/AgNPs SERS-based sensors were able to detect the spike protein at a concentration down to 9.3 × 10−12 M. Strong and dominant peaks at 1280, 1404, 1495, 1541 and 1609 cm−1 were spotted at a fraction of a minute. Moreover, direct, ultra-fast, facile, and affordable optoelectronic SiNWs/AgNPs sensors tuned to function as a biosensor for detecting the spike protein even at a trace level (pico molar concentration). The current findings hold great promise for the utilization of SERS as an innovative approach in the diagnosis domain of infections at very early stages.

A simple and green approach to the preparation of super tough IIR/SWCNTs nanocomposites with tunable and strain responsive electrical conductivity

Abstract Nanocomposites of single-wall carbon nanotubes in isobutylene isoprene rubber (IIR/SWCNTs) were successfully prepared by a simple and green wet process. The traditional melt mixing process and organic solvent dissolution suffered from unable to effectively disperse the SWCNTs of tangled structure, and degradation of polymer molecules, respectively. Our process very well avoided these two problems. The SWCNTs aqueous solutions emulsified by polyoxyethylene octyl phenol ether (OP-10) were firstly mixed and compounded with IIR rubber at a relatively high temperature, followed by the second step of melt compounding process with the addition of cross-linking agent and accelerators. The SWCNTs were dispersed uniformly, and a fine network was constructed in the matrix of the obtained IIR/SWCNTs nanocomposite with a low percolation threshold. With the concentration of SWCNTs as low as 2 phr, the IIR/SWCNTs nanocomposite received an electrical conductivity of 10−6∼10−3 S/cm, and a 71% improvement of tensile strength. By varying the loadings of SWCNTs in a certain range, the tensile strength, electrical conductivity, and dielectric property were found tunable. Besides, the nanocomposites also presented strain responsive specific resistance, excellent elongation (600–740%), and better heat resistance.

Efficiency improvement of P3CT-Na based MAPbI3 solar cells with a simple wetting process

The averaged power conversion efficiency of polyelectrolytes (P3CT-Na) based MAPbI3 solar cells can be increased from 14.94% to 17.46% with a wetting method before the spin-coating process of MAPbI3 precursor solutions. The effects of the wetting process on the surface, structural, optical and excitonic properties of MAPbI3 thin films are investigated by using the atomic-force microscopic images, x-ray diffraction patterns, transmittance spectra, photoluminescence spectra and Raman scattering spectra. The experimental results show that the wetting process of MAPbI3 precursor solution on top of the P3CT-Na/ITO/glass substrate can be used to manipulate the molecular packing structure of the P3CT-Na thin film, which determines the formation of MAPbI3 thin films.