ß-Cyclodextrin capped ZnS nanoparticles for CER-assisted colorimetric and spectrophotometric detection of Pb2⁺, Cu2⁺, and Hg2⁺ in an aqueous solution.

Herein, simple, low-cost, and room-temperature synthesis of beta-cyclodextrin (ß-CD) stabilized zinc sulfide nanoparticle (ZnS NP) through the chemical precipitation method has been reported for cation exchange reaction (CER) based colorimetric sensing of Pb2+, Cu2+, and Hg2+. Formation of ß-CD stabilized ZnS NPs (ZnS@ß-CD) was verified by physicochemical characterization techniques such as XRD, XPS, FE-SEM, and TEM. ZnS@ß-CD NPs showed color change selectively for the metal ions Pb2⁺, Cu2⁺, and Hg2⁺ among the various metal ions including Sn2⁺, Cr³âº, Mn2⁺, Fe³âº, Co2⁺, Ni2⁺, and Cd2⁺. The solubility product of reactants and the transformed products are the reason for selective CER of ZnS@ß-CD NPs towards Pb2⁺, Cu2⁺, and Hg2⁺ ions. ZnS@ß-CD NPs dispersion revealed rapid color change from white to orange, black, and bright yellow on the addition of higher concentrations of Pb2⁺, Cu2⁺, and Hg2⁺ respectively. This color change is due to the formation of complete CER-transformed nanostructures such as PbS, CuS, and HgS in higher concentrations (10⁻1- 10⁻³ M) of corresponding metal ions. The partial CER altered products Zn1-x,PbxS, Zn1-xCuxS and Zn1-xHgxS were detected due to the appearance of pale color in the lower metal ions concentrations of 10⁻4 - 10⁻6 M. This CER assisted transformation was also monitored through spectrophotometric methods. Moreover, infrared spectroscopic analysis was used to testify the structure of CER transformed product. The synthesized ZnS@ß-CD NPs act as an efficient CER-based sensor for distinguishing and determining Pb2⁺, Cu2⁺, and Hg2⁺ at different level concentrations in the aqueous solution.

ß-Cyclodextrin-Stabilized CuO/MXene Nanocomposite as an Electrode Material for High-Performance Supercapacitors.

Supercapacitors are the best energy storage systems due to their high power density, quick charge/discharge rate, and long-term reliability. In this study, ß-cyclodextrin-stabilized CuO nanoparticles (CuO@ßCD NPs) were synthesized through a simple reduction method and anchored on the surface of MXene nanosheets in three different proportions (1:1, 4:1, and 1:4) to obtain CuO@ßCD/MXene nanocomposites through the wet-impregnation method. The formation of CuO@ßCD NPs and their physicochemical characteristics were verified by XRD, XPS, FE-SEM, and HR-TEM analysis. The actual focus is on the evaluation of the electrochemical performances of CuO@ßCD, MXene, and CuO@ßCD/MXene nanocomposites for supercapacitor applications. The cyclic voltammetry and galvanostatic charge-discharge analysis revealed the pseudocapacitance and an improved specific capacitance of 1693.43 F g-1 at 0.90 A g-1 for the CuO@ßCD/MXene (1:1) nanocomposite. The electrochemical impedance analysis displays superior electrical conductivity with a low charge transfer resistance value on incorporating CuO@ßCD between the MXene layers. Furthermore, the CuO@ßCD/MXene (1:1) nanocomposite exhibited improved long-term cycling stability by retaining 86% of its initial specific capacitance even after the 10,000th cycle at the current density of 4.54 A g-1. Based on the electrochemical performance, the CuO@ßCD/MXene (1:1) nanocomposite proves its suitability as an electrode material for supercapacitor application with long-term cycling stability and rate capability.