RESUMO
The metal chalcogenides (MCs) for sodium-ion batteries (SIBs) have gained increasing attention owing to their low cost and high theoretical capacity. However, the poor electrochemical stability and slow kinetic behaviors hinder its practical application as anodes for SIBs. Hence, various strategies have been used to solve the above problems, such as dimensions reduction, composition formation, doping functionalization, morphology control, coating encapsulation, electrolyte modification, etc. In this work, the recent progress of MCs as electrodes for SIBs has been comprehensively reviewed. Moreover, the summarization of metal chalcogenides contains the synthesis methods, modification strategies and corresponding basic reaction mechanisms of MCs with layered and non-layered structures. Finally, the challenges, potential solutions and future prospects of metal chalcogenides as SIBs anode materials are also proposed.
RESUMO
A novel facile method for on-site determination of sulphite in wine using a gas-diffusion microfluidic paper-based analytical device (µPAD) combined with surface-enhanced Raman spectroscopy (SERS) was explored. The inexpensive and disposable µPAD was realized by sandwiching the ZnO-paper disc and integrating gas-diffusion separation and gas preconcentration on a paper-based platform. Through extensive condition optimization, the SERS signal at a shift of 620 cm(-1) and the concentration of SO2 showed good linearity in the range of 5-300 µg mL(-1). The linear correlation coefficient was 0.995 and the detection limit for sulphite was found to be 2 µg mL(-1). Ultimately, this proposed method was applied to the determination of sulphite in wine, which can be essentially paralleled with the official method. Endowed with portability, minimal reagent consumption, and operational simplicity, this developed device would find broad utilization for on-site monitoring of sulphite.
RESUMO
A novel aqueous two-phase system (ATPS) composed of ß-cyclodextrin (ß-CD) derivative and acetone was developed for enantioselective extraction of racemic phenylsuccinic acid (PSA). Binodal curves, tie-lines, and critical points for the investigated ATPS were determined and the experimental tie-lines data were successfully correlated by Othmer-Tobias, Bancroft, and Setschenow-type equations. ATPS containing sulfobutyl ether-ß-CD (SBE-ß-CD) exhibited better enantioselectivity than that using carboxymethyl-ß-CD (CM-ß-CD). To optimize enantioselective partitioning conditions of PSA in acetone/SBE-ß-CD ATPS, three factors (PSA concentration, pH, and equilibrium temperature) were analyzed by using central composite design in response surface methodology. The calculated equilibrium constants of inclusion complexation are 1638.64M-1 for SBE-ß-CD-(R)-PSA and 835.84M-1 for SBE-ß-CD-(S)-PSA, respectively. Under the optimized conditions, the separation factor of 3.14 and high enrichment efficiency (ER=98.06%, ES=99.25%) were simultaneously achieved in a single step.