MXenes are a family of two-dimensional (2D) materials that have drawn a lot of interest recently because of their distinctive characteristics and possible uses in a variety of electronic devices.

In this study, magnetite nanoparticles (Fe₃O₄ NPs) were synthesized using Baccaurea ramiflora leaf extracts and characterized by visual observation, UV–Vis, FTIR, XRD, FESEM, and EDS. The UV−Vis spectrum showed continuous absorption at 300–500 nm, confirming the formation of Fe₃O₄ NPs. FTIR revealed that compounds containing the O-H group act as reducing agents during Fe₃O₄ NPs formation. Agglomerated spherical NPs were observed in the FESEM image. The prominent peak at ~6.4 keV in the EDS spectrum ascertained the existence of Fe, while the sharp peak at ~0.53 keV confirmed the presence of elemental oxygen. XRD patterns affirmed the crystalline nature. The size of as-synthesized NPs was observed to be 8.83 nm. The catalytic activity of Fe₃O₄ NPs for the reduction of methylene blue (MB) dye was monitored by UV–Vis. The maximum absorption peak of MB dye at 664 nm was almost diminished within 20 min, which revealed Fe₃O₄ NPs could be an excellent catalyst for wastewater treatment.

A novel organic polyazo dye is synthesized by the diazotization of aromatic aniline, followed by coupling it with sulfanilic acid and N,N-dimethylaniline. Characterization was done by ¹H-NMR, ¹³C-NMR, and FTIR spectroscopy. Differential scanning calorimetry (DSC) reveals that phase transition for this molecule is exothermic. The optical band gap is estimated from the absorption cutoff point using UV-Visible spectroscopy. Thermal gravimetric analysis (TGA) addresses the thermal stability of the molecule and is found to be at ∼250 °C. The structure of the synthesized molecule is analogous to that of methyl orange and contains three azo groups. These three azo groups help accept more than two protons and provide two pK_a values when diprotic acid or a mixture of acids is used in different titrations. Specifically, when a polybasic acid is in strong base titration, the pK_a values were found to be 3.5 and 9.1. Moreover, for strong base and (strong + weak) acid mixture titration, the pK_a values are found to be 9.2 and 3.3. Furthermore, the pK_a values are found to be 8.6 and 2.8 for (strong and weak) base mixture and (strong and weak) acid mixture titration, respectively. Owing to its increased proton accepting capacity, it can be found in the two pH ranges of 2.1–3.8 for orange color and 8.2–9.8 for yellow color, thus indicating a unique property as a universal indicator for acid–base titration. The dissociation constant of this dye is found to be 3.4 × 10⁻⁶, determined in a mixed aqueous solution of 10 wt% ethanol, and a linear relationship between pK_a and pH is observed in this solvent system.

The reversible reaction of the photoisomerization and thermal reset of photochromic spiropyrans and merocyanine deposited on the MoS₂FET channel.

Light irradiation, ambient gas, and temperature all significantly increase hysteresis. Our observations show distinctive hysteretic behavior in MoS ₂ -FET in an oxygen environment at 1 atm.

Emerging contaminants (ECs), including pharmaceuticals, endocrine disruptors, heavy metals, and per- and polyfluoroalkyl substances (PFAS), are becoming increasingly crucial to identify because of their toxicity, persistence, and resistance to traditional water treatment techniques. Even if they are accurate, traditional analytical methods are frequently costly, time-consuming, and instrumentally complex. With its ease of use, quick visual reaction, high sensitivity, and affordability, colorimetric sensing based on gold nanoparticles (AuNPs) has become a viable substitute in this regard for on-site EC monitoring. The synthesis, functionalization, and use of AuNPs for the colorimetric detection of new pollutants have advanced recently, as this review illustrates. Because of their special localized surface plasmon resonance (LSPR) characteristics, AuNPs can interact with target analytes to produce noticeable color changes. We talk about different synthesis techniques, such as the reduction of citrate and borohydride, and how they affect the optical characteristics and particle shape. Additionally, we investigate functionalization techniques that provide selectivity toward ECs using thiol ligands, DNA aptamers, polymers, and chelating agents. A thorough analysis is conducted of colorimetric detection techniques, encompassing both aggregation-based and non-aggregation-based systems. Detecting ions (cation, anion), pesticides, metals (heavy metals, alkali and alkaline earth metals, coinage metals, rare-earth metals), food (formalin, melamine, rhodamine dye, etc.), pathogens, mycotoxins, oligonucleotides (DNA, nucleic acids, protein, etc.), glucose, and drugs (antibiotics, allergens, etc.) has been examined in this review. Lastly, we discuss present issues such as probe stability and matrix interference and suggest future paths for the development of portable and field-deployable sensors.