Over the past decades, increasing research in metal-organic frameworks (MOFs) being a large family of highly tunable porous materials with intrinsic physical properties, show propitious results for a wide range of applications in adsorption, separation, electrocatalysis, and electrochemical sensors. MOFs have received substantial attention in electrochemical sensors owing to their large surface area, active metal sites, high chemical and thermal stability, and tunable structure with adjustable pore diameters. Benefiting from the superior properties, MOFs and MOF-derived carbon materials act as promising electrode material for the detection of food contaminants. Although several reviews have been reported based on MOF and its nanocomposites for the detection of food contaminants using various analytical methods such as spectrometric, chromatographic, and capillary electrophoresis. But there no significant review has been devoted to MOF/and its derived carbon-based electrodes using electrochemical detection of food contaminants. Here we review and classify MOF-based electrodes over the period between 2017 and 2022, concerning synthetic procedures, electrode fabrication process, and the possible mechanism for detection of the food contaminants which include: heavy metals, antibiotics, mycotoxins, and pesticide residues. The merits and demerits of MOF as electrode material and the need for the fabrication of MOF and its composites/derivatives for the determination of food contaminants are discussed in detail. At last, the current opportunities, key challenges, and prospects in MOF for the development of smart sensing devices for future research in this field are envisioned.
The subject of water contamination and how it gets defiled to the society and humans is confabulating from the past decades. Phenolic compounds widely exist in the water sources and it is emergent to determine the toxicity in natural and drinking water, because it is hazardous to the humans. Among these compounds, catechol has sought a strong concern because of its rapid occurrence in nature and its potential toxicity to humans. The present work aims to develop an effective electrochemical sensing of catechol using mesoporous structure of Fe3O4-TiO2 decorated on glassy carbon (GC) electrode. The creation of pure TiO2 using the sol-gel technique was the first step in the synthesis protocol for binary nanocomposite, which was then followed by the loading of Fe3O4 nanoparticles on the surface of TiO2 using the thermal decomposition method. The resultant Fe3O4-TiO2 based nanocomposite exhibited mesoporous structure and the cavities were occupied with highly active magnetite nanoparticles (Fe3O4) with high specific surface area (90.63 m2/g). When compared to pure TiO2, catechol showed a more prominent electrochemical response for Fe3O4-TiO2, with a significant increase in anodic peak current at a lower oxidation potential (0.387 V) with a detection limit of 45 μM. Therefore, the prepared magnetite binary nanocomposite can serve as an efficient electroactive material for sensing of catechol, which could also act as a promising electrocatalyst for various electrocatalytic applications.
The present study highlights the treatment of industrial effluent, which is one of the most life-threatening factors. Herein, for the first time, two types of NiO (green and black) photocatalysts were prepared by facile chemical precipitation and thermal decomposition methods separately. The synthesized NiO materials were demonstrated with various instrumental techniques for finding their characteristics. The X-ray diffraction studies (XRD) and X-ray photoelectron spectroscopy (XPS) revealed the presence of Ni2O3 in black NiO material. The transmission electron microscopic (TEM) images engrained the nanospherical shaped green NiO and nanoflower shaped black NiO/Ni2O3 materials. Further, the band gap of black NiO nanoflower was 2.9 eV compared to green NiO having 3.8 eV obtained from UV-vis spectroscopy. Meanwhile, both NiO catalysts were employed for visible light degradation, which yields a 60.3% efficiency of black NiO comparable to a 4.3% efficiency of green NiO within 180 min of exposure. The higher degrading efficiency of black NiO was due to the presence of Ni2O3 and the development of pores, which was evident from the Barrett-Joyner-Halenda (BJH) method. Type IV hysteresis was observed in black NiO nanoflowers with high surface area and pore size measurements. This black NiO/Ni2O3 synthesized from the thermal decomposition method has promoted better photocatalytic degradation of 4-chlorophenol upon exposure to visible light and is applicable for other industrial pollutants.
In this study, the fruit of Terminalia chebula, commonly known as chebulic myrobalan, is used as the precursor for carbon for its application in supercapacitors. The Terminalia chebula biomass-derived sponge-like porous carbon (TC-SPC) is synthesized using a facile and economical method of pyrolysis. TC-SPC thus obtained is subjected to XRD, FESEM, TEM, HRTEM, XPS, Raman spectroscopy, ATR-FTIR, and nitrogen adsorption-desorption analyses for their structural and chemical composition. The examination revealed that TC-SPC has a crystalline nature and a mesoporous and microporous structure accompanied by a disordered carbon framework that is doped with heteroatoms such as nitrogen and sulfur. Electrochemical studies are performed on TC-SPC using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. TC-SPC contributed a maximum specific capacitance of 145 F g-1 obtained at 1 A g-1. The cyclic stability of TC-SPC is significant with 10,000 cycles, maintaining the capacitance retention value of 96%. The results demonstrated that by turning the fruit of Terminalia chebula into an opulent product, a supercapacitor, TC-SPC generated from biomass has proven to be a potential candidate for energy storage application.