Monitoring of food-based products is mandatory in recent days as a result of increasing health-related issues and to produce ready-to-eat foods. Phenolic compounds in foods improve human health owing to their antioxidant properties. In the food industry, antioxidants are coated and added to improve the food’s quality and to alleviate health issues. Among these, gallic acid (GA) is a widely known abundant phenolic acid found in numerous foods because of its health benefits. Here, we propose a zeolitic imidazolate framework (ZIF-8) functionalized with guar gum (GG) for GA sensing. Morphological studies confirm the nanostructured rhombic dodecahedral ZIF-8 particles embellished on the surface of GG microlayers. The proposed sensor shows excellent electrocatalytic activity toward GA sensing with a wide linear range of 200 nM – 2.5 mM with a detection limit of 60 nM. In addition, the composite offers significant selectivity and good stability up to 84% for 100 cycles and shows acceptable repeatability and reproducibility. Finally, the practical utility investigated in unspiked wine, grape juice, and tea samples offers exceptional sensing with remarkable recovery. Hence, the proposed [email protected] composite can be used to fabricate a sensor devices for food product testing.

Single crystalline 4H-SiC is a wide-gap semiconductor with optical properties that are poised to enable new applications in microelectromechanical systems (MEMS) and quantum devices. A number of key hurdles remain with respect to the micro and nano-fabrication of SiC to prepare precise photonic structures with nanometer-scale precision. These challenges include development of a fast, scalable etching process for SiC capable of producing a sub-nanometer roughness semiconductor surface while simultaneously reducing the total thickness variation across a wafer. Our investigation into UV photoelectrochemical processing of SiC reveals high dopant-type selectivity and the advantage of multiple etch stops to reduce layer thickness variation. We demonstrate dopant-type selectivities >20:1 using a single step and a >100x reduction in surface variation by combining two etch stops. Moreover, the etch rate is fast (>4 μm/hr) and the etched surface is smooth (~1 nm RMS). These results demonstrate a scalable path to the fabrication of precise nanoscale SiC structures and electronic devices that will enable the next generation of MEMS and photonic quantum devices.

Due to the large polarization resistance (Rp) of positrodes (namely, air/steam electrodes), it is vital to develop high-performance and cost-effective positrodes to improve the performance of protonic ceramic cells (PCCs). In this work, we report a La1.2Sr0.8NiO4+δ (LS8N) positrode decorated with (La,Sr)CoO3-δ (LSC) nanoparticles by infiltrating Co(NO3)2 solution. Rp of a bare electrode was 4.22 Ωcm2 at 600°C, and reduced by almost ten times to 0.49 Ωcm2 by infiltrating with a 0.2 molL-1 Co(NO3)2 solution. Furthermore, although Rp of the bare electrode increased after a durability test by exposing to Ar – 20% O2 – 3% H2O at 600°C for 100 h, Rp of the infiltrated electrode further decreased after the durability test. For example, Rp of the electrode infiltrated with 0.2 molL-1 Co(NO3)2 solution reduced to 0.37 Ωcm2, which is attributed to the enhancement of the LSC/LS8N interface. The good electrochemical performance and durability of the positrodes with LSC/LS8N heterogeneous interface, which can be optimized by controlling the parameters for the infiltration process, suggest a potential strategy for designing excellent positrodes for PCCs.

The photochemical activation process is a promising way to operate metal oxide gas sensors at room temperature. However, this technique is only used in n-type semiconductors. In this study, we report a highly stable p-type copper gallium oxide (CuGaO2) gas sensor fabricated through the facile sol-gel process. The sensor is capable of detecting O3 gas at room temperature, and its gas response can be further enhanced by ultraviolet (UV) activation. The highest gas response of 7.12 to 5 ppm O3 gas at a UV intensity of 10 mW/cm-2 is achieved at room temperature. In addition, the CuGaO2 sensor shows excellent long-term stability, with a degradation of approximately 3% over 90 days. These results strongly support the solution-processed CuGaO2 as a good candidate for room-temperature gas sensors.

A portable electrochemical platform that detects methylprednisolone in two switchable modes has been developed. Both selected modes, square wave voltammetry and stochastic, provide qualitative and quantitative analysis of the analyte. Under optimal conditions, the platform recorded the following linear concentration ranges, between 1.00 and 1.00 × 10¬3 µmol L‒1 when using the square wave voltammetry mode, and a much wider range between 1.00 × 10¬‒9 and 1.00 × 10¬4 µmol L‒1 when using the stochastic mode. The limits of quantification recorded were: 1.00 fmol L-1 for the stochastic mode, and 1.00 µmol L-1 for the square wave voltammetry mode. The developed platform was successfully applied for the assay of methylprednisolone in real samples (pharmaceutical dosage form and surface water), when recoveries higher than 90.00% were obtained.

The cathodic polarization behavior of UNS S13800 in NaCl solutions, ranging from dilute to saturated, and across a range of temperature values was studied using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and x-ray photoelectron spectroscopy (XPS). Analysis of the data indicated that the concentration of the solutions affected the ability of the oxide to catalyze reduction reactions. Dilute-to-low concentration solutions exhibited different Tafel slopes at low and high cathodic potentials while middle-to-high concentration solutions exhibited a single Tafel slope. The XPS data showed the oxides formed in low chloride solutions had a higher Fe2O3 concentration while the oxides formed in the high chloride solution had a higher Cr2O3 concentration. The EIS data showed the oxides had a similar thickness, but the oxide formed in the low chloride solution had a higher charge-transfer resistance while the oxide formed in the high chloride solution had a higher oxide resistance. A method for analyzing cathodic polarization curves on stainless steels is described and a framework for predicting the cathodic polarization response for UNS S13800 is developed, including a model for the diffusivity of dissolved oxygen as a function of chloride concentration and temperature.

Tin (Sn) films are electrodeposited on Au seed layers for the investigation of superconductivity. The effects of the presence of suppressing additives in electrolyte, the thickness of Sn films, and the room-temperature aging of deposited Sn films on the superconducting transition behavior are systematically studied. In addition, the crystallographic structure of electrodeposited Sn and its evolution along with aging time are characterized and are discussed in conjunction with the superconductivity behavior. The current work represents an important step towards the processing of technologically viable superconducting devices.

Mercury ions (Hg²⁺) pose serious threats to ecological environment and human health, which lead to the increasing demand for rapid and sensitive detection methods. Herein, an electrochemical sensor based on titanium dioxide/nickel nanoparticles-nitrogen doped carbon (TiO₂/Ni-NC) modified glassy carbon electrode (GCE) was developed for the detection of Hg²⁺. A Ti₃C₂T_X/NiMOF composite was synthesized by in-situ growing NiMOF on the multilayered structure of Ti₃C₂T_X. Through a facile pyrolysis treatment, TiO₂/Ni-NC was derived from Ti₃C₂T_X/NiMOF. N element doped carbon with a porous structure provided electron transfer channels for the electrochemical reaction and an ideal matrix for immobilizing catalytic sites. The TiO₂ and Ni nanoparticles were homogeneously distributed on the carbon matrix, and they exhibited good catalytic activity toward the electrochemical reaction of Hg²⁺. The accumulation of Hg²⁺ was promoted due to the chelation with the doped N element. The differential pulse anodic stripping voltammetry method coupled with the TiO₂/Ni-NC/GCE sensor was used to determine the concentration of Hg²⁺. Under optimal conditions, our proposed method presented a wide detection range (1 nM to 10 μM) and a low detection limit (0.79 nM). The sensor provided a satisfactory recovery in real water sample analysis, demonstrating the feasibility for environmental monitoring applications.

Proton exchange membrane fuel cells (PEMFCs) typically use Nafion®, which has many drawbacks, such as high cost, fuel crossover, and strenuous synthesis processes. As such, an alternative Nafion®-ionomer free proton conductor has drawn significant interest. Graphene oxide membrane (GOM) is a promising alternative due to its hydrophilic nature and attractive proton conductivity under humidified conditions. However, pristine GOMs have drawbacks, including fuel crossover, a high reduction rate of negatively oxygenated functional groups during fuel cell operation, and proton conductivity showing excessive orientation dependence. We focused on nanocomposite-GOM (N-GOM) based on PFSAs, hydrocarbon polymers, synthetic polymers, inorganic-organic polymers, biopolymers, metal-organic frameworks, and micro- and nano-engineered surfaces. GO nanosheets have outstanding dispersion rate and compatibility with ionomer matrices that can be functionalized by sulfonation, polymerization, phosphorylation, cross-linking, incorporated inorganic nanoparticles, and blending with matrix, microscale-nanoscale fabrication. The N-GOM exhibits high-performance fuel cells with improved proton conductivity, physicochemical properties, and low fuel crossover compared to Nafion®. For instance, SCSP/SF membranes with 3% functionalized GO (FGO) content displayed the highest conductivity of 26.90 mS/cm and the best selectivity (methanol) of 4.10 × 105 S/cm3 at room temperature. Moreover, a new scalable, efficient chitosan (CA)-based composite membrane (CA/GO) was fabricated. In addition, surface-patterned nanostructures in thin films increased the PEMFC output power to 950 mW/cm2, higher than 590 mW/cm2 for non-patterned Nafion®. Finally, we report on the optimal composition ratio for each material of the N-GOM-based membrane. This review discusses the most crucial developments in proton conductivity and outlines the current progress for the N-GOM as a revolutionary form of PEM. The general objective of this research is to review all possible modifications of N-GOM from the perspective of their practical application as electrolytes in fuel cells

We illustrate a simple and effective electrolyte extraction methodology from commercial 18650 lithium-ion cells. This methodology is based on a liquid-liquid extraction step, which is highlighted for robustness, reproducibility, and reliability. We assess the consumption of electrolyte by tracking compositional changes using liquid-state nuclear magnetic resonance (NMR) spectroscopy, supported by differential thermal analysis before and after cell cycling. An analysis method that monitors compositional dynamics is presented and shows the impact of these changes throughout a cell’s lifetime. Such methodology can be employed in the understanding of electrolyte degradation mechanisms to enhance the understanding of performance fade in commercial cells. Moreover, it will help build robust mathematical models that are able to predict the drive of cell degradation and ultimate failure.