Mesoporous cobalto-cobaltic oxide modified glassy carbon electrode for simultaneous detection of hydroquinone and catechol

Electrochemical Sensors Based on Transition Metal Materials for Phenolic Compound Detection

Electrochemical sensors have been recognized as crucial tools for monitoring comprehensive chemical information, especially in the detection of a significant class of molecules known as phenolic compounds. These compounds can be present in water as hazardous analytes and trace contaminants, as well as in living organisms where they regulate their metabolism. The sensitive detection of phenolic compounds requires highly efficient and cost-effective electrocatalysts to enable the development of high-performance sensors. Therefore, this review focuses on the development of advanced materials with excellent catalytic activity as alternative electrocatalysts to conventional ones, with a specific emphasis on transition metal-based electrocatalysts for the detection of phenolic compounds. This research is particularly relevant in diverse sectors such as water quality, food safety, and healthcare.

Novel Vanadia/meso-Co3O4 catalysts for the conversion of benzene-toluene-xylene to environmental friendly components via catalytic oxidation

Three - dimensional meso-porous Co₃O₄ was prepared by nanocasting pathway based on the use of mesoporous silica (KIT-6) as hard template with different Cobalt concentrations (0.5-2.5 mol ratio based on mesoporous silica KIT-6). The prepared samples was used as supports for preparing V₂O₅/Co₃O₄ (1, 6 wt% of V₂O₅) catalysts. The prepared samples were characterized by different techniques. The catalytic activity of the prepared samples were evaluated in the complete oxidation reaction of toluene, benzene, and/or p-xylene; (as model reactants of volatile organic compounds) in terms of CO₂. The catalytic reaction was carried out in a fixed-bed micro-reactor operated under atmospheric pressure and within the reaction temperature range of 200-400 °C. The data confirmed that the three dimensional-mesoporous Co₃O₄ (1.0 mole ratio) replicated sample possessed improved different parameters compared to those of the Co₃O₄ sample with other mole ratios. The data reflected the yield of Co2 is decreased upon the increase in reaction temperature to 400°C. 1 wt.% V₂O₅/m-Co₃O₄ catalyst shows a reverse direction, the CO₂ yield slowly increased in the range 150-250 °C, then jumped at 300 °C until maximum yield (100%) is observed at 400 °C. 1 wt.% V₂O₅/m-Co₃O₄ catalyst was found to be the active and selective promised catalyst for the complete oxidation of either individual aromatic volatile organic compounds (benzene, toluene, and/or xylene) and/or their mixtures to 100% CO₂.

A study on the electrochemical behavior of hydroquinone at a nanometer cobalt/l-glutamate-modified electrode

A new electrochemical sensor for hydroquinone (HQ) was prepared. The electrochemical sensor was modified by electrodeposition and electrochemical polymerization to modify nanometer cobalt (nano-Co) and poly-l-glutamic acid (poly-l-glu) on the surface of a glassy carbon electrode (GCE). Then, the electrochemical behavior of hydroquinone on the electrochemical sensor was investigated by cyclic voltammetry (CV). The experimental conditions were optimized from the aspects of electrolyte type, concentration, acidity, enrichment time and scanning speed. The experimental results showed that under optimized conditions the oxidation peak current has a good linear relationship with the concentration of hydroquinone in the range of 3.85 × 10⁻⁶ to 1.30 × 10⁻³ mol L⁻¹ (R² = 0.9998). Moreover, there was a low detection limit of 4.97 × 10⁻⁷ mol L⁻¹. When the sensor was used for the analysis of hydroquinone in water samples, the recoveries with satisfactory results were in the range of 97.2–102.6%.

A new electrochemical sensor for hydroquinone (HQ) was prepared.

Fabrication of ZIF-67@three-dimensional reduced graphene oxide aerogel nanocomposites and their electrochemical applications for rutin detection

Three-dimensional reduced graphene oxide aerogel (3D rGA) was synthesized by hydrothermal method and cobalt imidazolate framework-67 (ZIF-67) was further grown in situ on the 3D rGA matrix directly. The resultant ZIF-67@3D rGA nanocomposite was checked by different techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectrophotometry (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and thermo-gravimetric analysis (TGA). The presence of 3D rGA acted as the backbone for the loading of ZIF-67, and the resultant ZIF-67@3D rGA nanocomposite exhibited an interconnected porous structure with large surface area and high conductivity due to synergistic effects, which was applied to the electrode modification and used for rutin detection. The developed method showed excellent performance with a wider linear range (0.05-200.0 μmol/L) and lower detection limit (0.028 ± 0.0016 μmol/L, S/N=3). Various samples including the compounded rutin tablets and onions were analyzed by this modified electrode with satisfactory results.