Mixed Ni²⁺Co²⁺ Transition Metal Nitroprusside: Determination of Its Electrochemical Behavior and Electrocatalytic Activity towards the Oxidation of Phenylhydrazine

Abstract

Coordination polymers have received considerable attention in recent years as electrocatalytic materials for the construction of electrochemical sensors. This is due to their high sensitivity and selectivity towards the electrochemical detection of various molecules, particularly pollutants and metabolites, which commonly appear in low concentrations and in complex matrices. In this work, the construction of an electrochemical sensor was performed for the detection of phenylhydrazine, which is a strong pollutant, based on a mixed Ni 2 + Co 2 + transition metal nitroprusside (NiCoNP). NiCoNP was synthesized by chemical coprecipitation, and characterized using Xray diffraction, TGA, and IR and XPS spectroscopies. Its structural characterization indicates that the material was a solid solution, with a cubic Fm � 3m structure and a stoichiometry of Ni 0.59 Co 0.41 [Fe(CN) 5 NO] ⋅ 5H 2 O. The material showed quasireversible electron transfer behavior associated to the charge transfer between the metallic centers of the nitroprusside and the concomitant intercalation of K + ions within the crystal lattice. The sensor based on NiCoNP exhibited a high electrocatalytic activity for the electrooxidation of phenylhydrazine without kinetic limitations, and a wide large linear range (0.5-12 mM), high sensitivity (86.87 μA ⋅ cm À 2 /mM), and LOD of 266 μM. Such device showed a rapid and selective response towards phenylhydrazine. In conclusion, the NiCoNP under study showed a promising electrocatalytic activity for the development of electrochemical sensors.