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[Display omitted] • The hierarchical ZnO nanostructures and various metal (Cu, Ni, and Fe) oxide decorations on the hierarchical ZnO were synthesized by the one step cyclic-microwave method. • The photocatalytic activity of the ZnO, CuO/ZnO, Fe 2 O 3 /ZnO and NiO/ZnO were investigated by Methylene blue degradation under UV light irradiation. • The photocatalytic performance of ZnO is an increase by decorated NiO and CuO. • The performance of the Ni(5)-ZnO photocatalyst for Rhodamine B and Methyl Orange dyes were also examined. In this work, the role of the p-n junction in the photocatalytic degradation of various dyes in contaminated wastewater was studied. The n-type ZnO was synthesized by the cyclic-microwave method and was enhanced by various metal oxides, e.g., CuO, NiO, and Fe 2 O 3. The materials were characterized by various methods. The degradation of Methylene blue (MB), Methyl orange (MO), and Rhodamine B (RhB) under the photocatalysts and UV light irradiation was examined. From the results, the performance of the dye degradation by the p-n CuO/ZnO and NiO/ZnO materials was better than that of the pure ZnO. On the other hand, the n-n heterostructure Fe 2 O 3 /ZnO showed a decrease in photocatalytic performance. The photocatalyst with the highest performance was Ni(5)-ZnO, which can degrade dyes contaminating water by greater than 99.71%. The physical principle behind the increase in the photocatalytic performance is due to the formation of the p-n junction by CuO and NiO to the n-type ZnO, resulting in the efficient generation of electron-hole pairs. [ABSTRACT FROM AUTHOR]

Abstract: Metal oxide semiconductor nanostructures offer potential advantages in sensing applications due to their large surface to volume ratio, lower electron recombination rate, and high stability. However, most methods produce nanostructures with random sizes, distribution and orientations, which are not reliable for practical applications because of poor reproducibility. In this work, homogeneous carbon-doped WO3 nanorods are developed based on the glancing angle deposition (GLAD) technique using radio-frequency magnetron sputtering and investigated for NO2 gas sensing application. The carbon doping is achieved by using acetylene gas as a carbon source. Characterization based on scanning electron microscopy, Auger electron spectroscopy and X-ray diffraction confirm the formation of uniform carbon-doped crystalline WO3 nanorods. The gas-sensing results reveal that carbon-doped WO3 nanorods sensor exhibits not only high response and selectivity to NO2 (0.5–5ppm) but also at low operating temperature (150°C) compared with the undoped ones. The observed gas-sensing enhancement may be attributed to the increase of specific surface area and the decrease of activation energy by carbon doping. [Copyright &y& Elsevier]

Abstract: In this work, a new paper-based electrochemical sensor is developed as a low-cost and disposable point-of-care device for pre-screening purpose. Electrodes of this new sensor are fabricated using two printing techniques, i.e. screen-printing for base material and inkjet-printing for modifying functional material, and the performance of fabricated sensors for Ascorbic acid detection is demonstrated. The paper-based device consists of three electrodes including Polyaniline (PANI) modified Screen-Printed Carbon Electrode (SPCE) as working electrode and two bare SPCEs as reference and counter electrodes. Three SPCEs are initially screen-printed on a filter paper, and PANI is consecutively inkjet-printed on the designated working SPCE. Its electrochemical performances are systematically investigated towards Ascorbic acid using Cyclic Voltammetry (CV) with different Acetate buffer pHs and numbers of printed-PANI layers. The CV results show that the optimal buffer pH and number of PANI layers are 4.0–5.0 and 5, respectively. Consequently, real-time detection of Ascorbic acid concentration is performed using Chronoamperometry technique under the optimal conditions from previous CV studies. From the results, the sensor exhibits a good sensitivity of 17.7μA/mM and a moderately low limit-of-detection of 30±3μM in a concentration range of 30–270μM. According to cost versus performance, the utilization of paper-based sensor with inkjet-printed PANI modified SCPE is an alternative choice for low-cost and disposable point-of-care applications. [Copyright &y& Elsevier]

Abstract: In this work, unloaded WO3 and 0.25–1.0wt% Pt-loaded WO3 powders were produced by flame spray pyrolysis (FSP) and structurally characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM). The BET surface area (SSA BET) of the nanoparticles was measured by nitrogen adsorption. Thick WO3 films (30μm) on alumina substrates interdigitated with gold electrodes were prepared by spin-coating technique and tested for gas sensing towards H2, CO, C2H4 and C2H5OH gases at concentrations ranging from 0.01 to 1vol% in dry air with operating temperatures ranging from 150 to 300°C. The sensing films exhibited excellent H2 sensing performances with a very high response, short response time and high selectivity towards CO, C2H4 and C2H5OH gases. The response (within seconds) and recovery (within minutes) times were very fast. It was found that 1.0wt% Pt-loaded WO3 sensing films showed extremely excellent H2 sensing performances at 150°C with the highest sensor response (S ∼1.34×105) and the highest selectivity compared to the other gases. [Copyright &y& Elsevier]

[Display omitted] • Carbon paste with IL and graphene was used to screen-print electrochemical electrodes. • Optimal design had 15.70 mm2 WE and 12.57 mm2 CE active area, and 25 mm overall length. • PMPlm ionic liquid gave the highest CV response at an optimal PMPlm content of 1.0 w%. • SPIL-GE provided enhanced CV responses to (Fe(CN) 6)3-/4-, dopamine and hydroquinone. In this work, a highly sensitive and disposable screen-printed ionic liquid-graphene electrode (SPIL-GE) was developed for electrochemical sensing. The paste for screen printing was facilely prepared by mixing IL with electrolytically exfoliated graphene in poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (GP/PEDOT/PSS) and carbon paste (CP) via ball milling. The IL-GP paste was then screen printed to form working and counter electrodes (WE & CE) followed by screen printing of Ag/AgCl reference electrode and insulator layer on a polyethylene substrate. Electrode geometries were optimized for electrochemical sensing, arriving at an optimal design with an overall electrode length of 25 mm, and CE and WE active areas of 15.70 and 12.57 mm2, respectively. SPIL-GEs employing six ILs with imidazolium and pyridinium cations were assessed for electrochemical sensing of K 3 Fe(CN) 6. The pyridinium-type IL, namely 3-methyl-1-propylpyridinium bis(trifluoromethyl sulfonyl)imide (PMPlm), was found to exhibit the highest CV peak currents compared with other ILs at an optimal PMPlm content of 1.0% (w/w). Characterization with scanning electron microscopy and Fourier-transform infrared spectroscopy confirmed the presence of PMPlm, GP/PEDOT/PSS and CP in SPIL-GEs. The electrochemical performance of the optimal SPIL-GE towards the three common analytes including ferri/ferro cyanide (Fe(CN) 6)3-/4- redox couple, dopamine and hydroquinone were compared with the screen-printed carbon and graphene electrodes (SPCE & SPGE). From the results, the SPIL-GE demonstrated larger anodic currents with lower oxidation potentials for the three analytes than SPGE and SPCE, respectively. Therefore, the SPIL-GE could be a potential candidate for advanced electrochemical sensing applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • WO 3 /WC hybrid is designed and synthesized by facile annealing method. • WO 3 /WC hybrid with low Zn2+ intercalated potential is demonstrated. • The strong interaction and electronic coupling between WO 3 and WC are determined. • Significant rate and cycling stability can be achieved for WO 3 /WC hybrid. • The WO 3 /WC||MnO 2 /graphite rocking‐chair ZIBs achieve excellent performance. Aqueous Zinc-ion batteries (ZIBs) are recognized as the most pivotal competitor of lithium-ion batteries due to their abundant reserves, remarkable safety and affordable cost. However, the uncontrollable dendritic growth and extremely low utilization (<5%) of zinc metal anode severely limit the practicality and energy density of ZIBs. Herein, a novel rocking-chair ZIBs with excellent cycling stability and high energy density is developed via employing tungsten oxide/carbide (WO 3 /WC) layered heterogeneous hybrid with strong-coupling effect as the intercalated anode and MnO 2 /graphite cathode. Benefiting from the favorable interface energy and electronic coupling with prominent charge-transfer between WO 3 and WC, the WO 3 /WC//Zn batteries deliver admirable capacity of 164 mAh g−1 under 0.1 A g−1 with suitable Zn2+ intercalated potential of 0.43 V (vs. Zn2+/Zn), long-term cyclability with 90.2% after 1000 cycles under 1 A g−1, and reversible Zn2+ intercalation behavior. Consequently, the assembled WO 3 /WC||MnO 2 /graphite rocking-chair ZIBs offer excellent capacity of 69 mAh g−1 at 0.1 A g−1, impressive cyclic stability (100% after 10,000 cycles) and exceptional energy density of 85 Wh kg−1, suppressing most of reported rocking‐chair ZIBs. Therefore, this research provides a novel insight for designing safe and high-efficient ZIBs. [ABSTRACT FROM AUTHOR]

This work demonstrated that the performance improvement of nitrogen-doped reduced graphene oxide (N-rGO) electrodes over reduced graphene oxide (rGO) electrodes for supercapacitors could be further enhanced by violet laser treatment (VLT). A specific capacitance of 30 and 145 F g−1 was obtained for rGO and N-rGO electrodes, respectively. When using N-rGO with proper VLT, a high specific capacitance of 214 F g−1 could be achieved. In addition, the percentage of capacitive retention of the N-rGO with VLT remaining 94% after 10,000 cycles with a slower self-discharge rate at 0.55 V h−1, comparing to 0.91 V h−1 for N-rGO. Systematic investigations of N-rGO with VLT were carried out by using different film characterization techniques. The surfaces of N-rGO with VLT exhibit an increase in the number of exfoliated graphene oxide sheets with more roughness when increasing the fluence of laser. It was also found that there are the decrease in oxygen/nitrogen-containing functional groups contents and the increases in graphitic carbon phase with C C sp2-hybridization with the influence of laser. These may explain the improvements of the reported charge storage ability, electrode stability, and self-discharge rate. • Nitrogen doped reduced graphene oxide (N-rGO) is prepared via hydrothermal method. • Violet laser treatment (VLT) is simple, fast, not expensive, and effective. • VLT on N-rGO (N-rGO-V5) can enhance the C sp around 48%, compared with N-rGO. • VLT can improve self-discharge or leakage current. • N-rGO-V5 shows long cycle life at least 94% after 10,000 charge-discharge cycles. [ABSTRACT FROM AUTHOR]

A novel composite CuAl 2 O 4 /TiO 2 /CuO films were successfully deposited on quartz substrate using a simple and low-cost sparking process. The as-deposited films were then annealed at 300, 700 and 1100 °C for 1 h under atmospheric pressure. Morphology, structural and optical properties were characterized by SEM, TEM, XRD, XPS and UV/vis spectroscopy. The results show the nanoparticles with size of 20-50 nm deposited and aligned as a network on the substrate. The number of particles decreased with increased annealing temperature. Meanwhile, SAED and XRD patterns of the annealed films at 700 °C consisted of CuO, CuAl 2 O 4 and rutile TiO 2 phases. Interestingly, double band gap of 3.50 eV and 2.56 eV were obtained in the annealed films at 700 °C. The photocatalytic activity of CuAl 2 O 4 /TiO 2 /CuO films annealed at 700 °C was optimized condition. This is because the double band gap composite films can reduce the e−/h+ pair recombination. Therefore, novel composite films after annealing at 700 °C can improve the photocatalytic efficiency under visible light. [ABSTRACT FROM AUTHOR]

This study reports on the application of an extreme learning machine (ELM) in near-real-time kidney monitoring via urine neutrophil gelatinase-associated lipocalin (NGAL) detection with a 3D graphene electrode. This integration marks the first instance of combining a graphene-based electrode with machine learning to enhance the NGAL detection accuracy, building on our group's 2020 research. The methodology involves two key components: a graphene electrode functionalized with a lipocalin-2 antibody for NGAL detection and the ELM application for improved prediction accuracy by using urine analysis data. The results show a significant 15% increase in the area under the curve (AUC) for NGAL determination, with error reduction from ±6 to 0.54 ng/mL within a linear range of 2.7-140 ng/mL. The ELM also lowered the detection limit from 14.8 to 0.89 ng/mL and increased accuracy, precision, sensitivity, specificity, and F1 score for AKI prediction by 8.89, 30.69, 6.78, 9.94, and 19.07%, respectively. These findings underscore the efficacy of simple neural networks in enhancing graphene-based electrochemical sensors for AKI biomarkers. ELM was chosen for its optimal performance-resource balance, with a comparative analysis of ELM, support vector machines, multilayer perceptron, and random forest algorithms also included. This research suggests the potential for miniaturizing AI-enhanced sensors for practical applications., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

In this work, we report a new phenomenon in electrochemical systems whereby uniform current steps of 1 mA per 0.5 × 0.5 × 0.1 cm 3 (width × width × depth) of electrode volume occurred during the electrodeposition of gold and silver nanoparticles onto 3D microporous graphene on nickel layers (GF/Ni) at room temperature. The effect was exhibited only at specific applied electrical potentials. The experiments (magnetic interference, temperature dependence, and surface area dependence) were repeated, and the results were reproducible. Finally, we proposed classical electrochemical theory using the Butler-Volmer equation and quantum theory using the Landauer formalism to describe this new effect. Both theories could be used to explain the experimental results: temperature dependence, surface area dependence, blocking effects, and external magnetic field dependence. In addition, the stepwise current presented in this work facilitates the trapping and supplying of a large amount of electric charge via an inherent magnetic field in a sharp time step (∼1 s). A video clip of the recorded effect can be found at https://youtu.be/pPJh45w1sUQ., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

In this work, the formic acid (CH 2 O 2 )-sensing properties of flame-made inverse spinel Zn 2 SnO 4 nanostructures were systematically studied by comparing with its parent oxides, namely ZnO and SnO 2 . All nanoparticles were synthesized via single nozzle flame spray pyrolysis (FSP) in one step and verified by electron microscopy, X-ray analysis, and nitrogen adsorption to exhibit high phase purity and high specific surface area. From gas-sensing measurements, the flame-made Zn 2 SnO 4 sensor displayed the highest response of 1829 towards 1000 ppm CH 2 O 2 at the optimal working temperature of 300 °C compared with ZnO and SnO 2 . In addition, the Zn 2 SnO 4 sensor presented a moderately low humidity sensitivity and high formic acid selectivity against several volatile organic acids, volatile organic compounds, and environmental gases. The enhanced CH 2 O 2 -sensing of Zn 2 SnO 4 was attributed to very fine FSP-derived nanoparticles with a high surface area and unique crystal structure, which could induce the creation of a large number of oxygen vacancies useful for CH 2 O 2 sensing. Moreover, the CH 2 O 2 -sensing mechanism with an atomic model was proposed to describe the surface reaction of the inverse spinel Zn 2 SnO 4 structure to CH 2 O 2 adsorption in comparison with that of the parent oxides. The results suggest that Zn 2 SnO 4 nanoparticles derived from the FSP process could be a promising alternative material for CH 2 O 2 sensing.

The efficiency of nerve guide conduits (NGCs) in repairing peripheral nerve injury is not high enough yet to be a substitute for autografts and is still insufficient for clinical use. To improve this efficiency, 3D electrospun scaffolds (3D/E) of poly(l-lactide- co -ε-caprolactone) (PLCL) and poly(l-lactide- co -glycolide) (PLGA) were designed and fabricated by the combination of 3D printing and electrospinning techniques, resulting in an ideal porous architecture for NGCs. Polypyrrole (PPy) was deposited on PLCL and PLGA scaffolds to enhance biocompatibility for nerve recovery. The designed pore architecture of these "PLCL-3D/E" and "PLGA-3D/E" scaffolds exhibited a combination of nano- and microscale structures. The mean pore size of PLCL-3D/E and PLGA-3D/E scaffolds were 289 ± 79 and 287 ± 95 nm, respectively, which meets the required pore size for NGCs. Furthermore, the addition of PPy on the surfaces of both PLCL-3D/E (PLCL-3D/E/PPy) and PLGA-3D/E (PLGA-3D/E/PPy) led to an increase in their hydrophilicity, conductivity, and noncytotoxicity compared to noncoated PPy scaffolds. Both PLCL-3D/E/PPy and PLGA-3D/E/PPy showed conductivity maintained at 12.40 ± 0.12 and 10.50 ± 0.08 Scm -1 for up to 15 and 9 weeks, respectively, which are adequate for the electroconduction of neuron cells. Notably, the PLGA-3D/E/PPy scaffold showed superior cytocompatibility when compared with PLCL-3D/E/PPy, as evident via the viability assay, proliferation, and attachment of L929 and SC cells. Furthermore, analysis of cell health through membrane leakage and apoptotic indices showed that the 3D/E/PPy scaffolds displayed significant decreases in membrane leakage and reductions in necrotic tissue. Our finding suggests that these 3D/E/PPy scaffolds have a favorable design architecture and biocompatibility with potential for use in peripheral nerve regeneration applications.

We report a new ready-to-use sensor for simultaneous determination of paraquat (PQ) and glyphosate (GLY) based on a graphite screen-printed electrode modified with a dual-molecularly imprinted polymer coated on a mesoporous silica-platinum core. Amino-mesoporous silica nanoparticles (MSN-NH 2 ) were first synthesized by a simple co-condensation method using tetraethyl orthosilicate and 3-aminopropyltrimethoxysilane. PtNPs were then decorated on the surface of MSN-NH 2 by chemical reduction. Finally, the dual-MIP was successfully coated on the MSN-PtNP core. This 3D-surface-imprinting strategy enhances the conductivity and monodispersity of the MSN-PtNPs@d-MIP. Quantitative analysis was performed by differential pulse voltammetry with an oxidation current appearing at -0.95 V for PQ and +0.97 V for GLY. The dual-MIP sensor shows good linear calibration curves in the range of 0.025-500 μM for both analytes with detection limits of 3.1 nM and 4.0 nM for PQ and GLY, respectively. The dual-MIP sensor shows high selectivity and specificity, attributed to the increased affinity of the imprinted cavities formed on the polymer film for the target PQ and GLY molecules. The proposed dual-MIP sensor was successfully applied to detect PQ and GLY concentrations simultaneously in water samples. The ready-to-use dual-MIP sensor is well suited for water-quality control and on-site applications without sophisticated instrumentation.

Aqueous zinc-ion batteries (ZIBs) with exceptional safety and cost-effective features have captured researchers' attention, but the cathode materials available still need to be further explored. Herein, a flower-like W/WO 3 hybrid is developed as a cathode of ZIBs. Impressively, the W/WO 3 -ZIBs exhibit extraordinary rate performance (158 mA h g -1 under 0.1 A g -1 ) and remarkable cycling performance (96% over 1000 cycles). Additionally, an electrochemical mechanism based on reversible Zn 2+ insertion/extraction in W/WO 3 is firstly demonstrated, and the impressive flexibility and excellent capabilities of the soft-packaged batteries are also realized. Therefore, this research will pave a novel consideration of metal/metal oxide hybrids in designing cathodes of ZIBs with high electrochemical performance.

In this work, CuO-loaded tetragonal SnO 2 nanoparticles (CuO/SnO 2 NPs) were synthesized using precipitation/impregnation methods with varying Cu contents of 0-25 wt% and characterized for H 2 S detection. The material phase, morphology, chemical composition, and specific surface area of NPs were evaluated using X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller analysis. From gas-sensing data, the H 2 S responses of SnO 2 NPs were greatly enhanced by CuO loading particularly at the optimal Cu content of 20 wt%. The 20 wt% CuO/SnO 2 sensor showed an excellent response of 1.36 × 10 5 toward 10 ppm H 2 S and high H 2 S selectivity against H 2 , SO 2 , CH 4 , and C 2 H 2 at a low optimum working temperature of 200 °C. In addition, the sensor provided fast response and a low detection limit of less than 0.15 ppm. The CuO-SnO 2 sensor could therefore be a potential candidate for H 2 S detection in environmental applications.

Sb2O3-loaded NaWO4-doped WO3 nanorods were fabricated with varying Sb contents from 0 to 2 wt% by precipitation/impregnation methods and their p-type acetylene (C2H2) gas-sensing mechanisms were rigorously analyzed. Material characterization by X-ray diffraction, X-ray photoelectron spectroscopy, scanning transmission electron microscopy and nitrogen adsorption indicated the construction of short NaWO4-doped monoclinic WO3 nanorods loaded with very fine Sb2O3 nanoparticles. The sensors were fabricated by powder pasting and spin coating and their gas-sensing characteristics were evaluated towards 0.08-1.77 vol% C2H2 at 200-350 °C in dry air. The gas-sensing properties of the NaWO4-doped WO3 sensor with the optimum Sb content of 1 wt% showed the highest p-type response of ∼250.2 to 1.77 vol% C2H2, which was more than 20 times as high as that of the unloaded one at the best working temperature of 250 °C. Furthermore, the Sb2O3-loaded sensor offered high C2H2 selectivity against CH4, H2, C3H6O, C2H5OH, HCHO, CH3OH, C8H10, C7H8, C2H4 and NO2. Mechanisms responsible for the observed p-type sensing and response enhancement behaviors were proposed based on the NaWO4-doped WO3-Sb2O3 (p-n) heterointerfaces and catalytic spillover effects. Consequently, the Sb2O3-loaded NaWO4-doped WO3 nanorods have potential as alternative p-type gas sensors for selective and sensitive C2H2 detection in various industrial applications.

Due to their cost effectiveness, high safety, and eco-friendliness, zinc-ion batteries (ZIBs) are receiving much attention nowadays. In the production of rechargeable ZIBs, the cathode plays an important role. Manganese oxide (MnO 2 ) is considered the most promising and widely investigated intercalation cathode material. Nonetheless, MnO 2 cathodes are subjected to challenging issues viz. limited capacity, low rate capability and poor cycling stability. It is seen that the MnO 2 heterostructure can enable long-term cycling stability in different types of energy devices. Herein, a versatile chemical method for the preparation of MnO 2 heterostructure on multi-walled carbon nanotubes (MNH-CNT) is reported. Besides, the synthesized MNH-CNT is composed of δ-MnO 2 and γ-MnO 2 . A ZIB using the MNH-CNT cathode delivers a high initial discharge capacity of 236 mAh g -1 at 400 mA g -1 , 108 mAh g -1 at 1600 mA g -1 and excellent cycling stability. A pseudocapacitive behavior investigation demonstrates fast zinc ion diffusion via a diffusion-controlled process with low capacitive contribution. Overall, the MNH-CNT cathode is seen to exhibit superior electrochemical performance. This work presents new opportunities for improving the discharge capacity and cycling stability of aqueous ZIBs.

The affordable surface-enhanced Raman scattering (SERS) substrates, with a structure consisting of densely distributed round-shape silver nanoclusters on anodic aluminum oxide (AAO) template, is fabricated by magnetron sputtering and anodization processes. The physical investigations show that the silver nanoclusters with size distribution ranging from 10 to 30 nm uniformly distributed on the top and in the bottom of the AAO nanochannels. The SERS activities from adsorbed probe molecules, i.e., methylene blue, on the SERS substrate surface indicate a high Raman enhancement factor for trace organic analysis. The SERS substrate is successfully utilized in the detection of a trace amount of three different proteins, bovin serum albumin, immunoglobulin G, and cardiac troponin T, also adsorbed on the substrate surface. Several spectral bands containing important molecular structures of these proteins are clearly observed and identified. The obtained results indicated a step forward to label-free biomolecular detections in chip-based biosensors.

Cardiac troponin T (cTnT) detection has been the focus of increased interest due to its role in myocardial infarction diagnosis. In this study, we report a relatively low coat technique to detect cTnT using a quartz crystal microbalance (QCM) sensor. A sensitive detection is achieved by introducing a QCM surface with a carboxylic polyvinyl chloride immobilization layer. The surface morphologies of this polymer film under varied deposition thickness have been investigated by field emission scanning electron microscopy and atomic force microscopy. A cTnT detection result from a modified QCM surface can be obtained within a short response time by a direct detection of the immunoreaction and a direct conversion of mass accumulation into a frequency shift, representing a measurable electrical signal. The relationship between the cTnT concentration and the response current from a QCM sensor shows detectability at the concentration of cTnT as low as 5 ng/ml.