Electrodeposition of dendritic gold/silver nanaoparticles on disposable screen-printed carbon electrode and its application of 4-mercaptopyridine in in situ electrochemical surface-enhanced Raman scattering

Selective Detection of Paraquat in Adulterated and Complex Environmental Samples Using Raman Spectroelectrochemistry

Growing demand for pesticides has created an environment prone to deceptive activities, where counterfeit or adulterated pesticide products infiltrate the market, often escaping rapid detection. This situation presents a significant challenge for sensor technology, crucial in identifying authentic pesticides and ensuring agricultural safety practices. Raman spectroscopy emerges as a powerful technique for detecting adulterants. Coupling the electrochemical techniques allows a more specific and selective detection and compound identification. In this study, we evaluate the efficacy of spectroelectrochemical measurements by coupling a potentiostat and Raman spectrograph to identify paraquat, a nonselective herbicide banned in several countries. Our findings demonstrate that applying -0.70 V during measurements yields highly selective Raman spectra, highlighting the primary vibrational bands of paraquat. Moreover, the selective Raman signal of paraquat was discernible in complex samples, including tap water, apple, and green cabbage, even in the presence of other pesticides such as diquat, acephate, and glyphosate. These results underscore the potential of this technique for reliable pesticide detection in diverse and complex matrices.

1-(Pyridin-4-yl)-4-thiopyridine (PTP) in the crystalline state - pure PTP and a cocrystal and salt

The first in situ preparation and single-crystal structure identification of pure 1-(pyridin-4-yl)-4-thiopyridine (PTP), C10H8N2S, a simple and basic derivative of mercaptopyridine, from a crystallization mixture is described. The same PTP was found in two multicomponent crystal forms with 3,5-dinitrobenzoic acid as a classic two-component cocrystal, namely, 1-(pyridin-4-yl)-4-thiopyridine-3,5-dinitrobenzoic acid (1/1), C7H4N2O6·C10H8N2S, and with 2-hydroxy-3,5-dinitrobenzoic acid as a salt formed via proton transfer from the hydroxy group of the acid to the pyridyl N atom of PTP, namely, 4-(4-sulfanylidene-1,4-dihydropyridin-1-yl)pyridin-1-ium 1-carboxy-3,5-dinitrophenolate, C10H9N2S+·C7H3N2O7-. The protonation energy of PTP is 944.64 kJ mol-1, indicating slightly greater N-basicity compared to pyridine, a well characterized and very basic chemical reference. A variety of molecular interactions can be observed in the three new crystal structures of PTP, which are all discussed in detail. Our findings confirm those of previous studies, indicating that PTP and 4-mercaptopyridine may, under suitable conditions, be chemically converted to one another, and that this process can be stimulated by light (UV-Vis).

Screen-Printed Electrodes Modified with Metal Nanoparticles for Small Molecule Sensing

Recent progress in the field of electroanalysis with metal nanoparticle (NP)-based screen-printed electrodes (SPEs) is discussed, focusing on the methods employed to perform the electrode surface functionalization, and the final application achieved with different types of metallic NPs. The ink mixing approach, electrochemical deposition, and drop casting are the usual methodologies used for SPEs' modification purposes to obtain nanoparticulated sensing phases with suitable tailor-made functionalities. Among these, applications on inorganic and organic molecule sensing with several NPs of transition metals, bimetallic alloys, and metal oxides should be highlighted.

Fabrication of liquid–liquid self-assembled Ag arrays on disposable screen-printed electrodes and their application in the identification and analysis of the adsorption behavior of organic carboxylates through in situ electrochemical surface-enhanced Raman scattering

A disposable Ag array@screen-printed electrode (SPE) was fabricated for the identification and analysis of the adsorption behavior of organic carboxylates in in situ electrochemical surface-enhanced Raman scattering (EC-SERS).

Flexible plasmonic graphene oxide/heterostructures for dual-channel detection

Schematic representation of the flexible plasmonic graphene oxide (GO)/heterostructure-based device with dual functionality for electrochemical and SERS detection.

Monitoring surface transformations of metal carbodiimide water oxidation catalysts by operando XAS and Raman spectroscopy

Chemical and structural transformations at the electrode surface of metal carbodiimides MNCN (M = Co, Ni, Mn, Cu), were studied by operando Raman and XAS spectroscopy during electrocatalytic water oxidation