Pd-modified PEDOT layers obtained through electroless metal deposition—electrooxidation of glycerol

Lignosulfonate-Assisted In Situ Deposition of Palladium Nanoparticles on Carbon Nanotubes for the Electrocatalytic Sensing of Hydrazine

This paper presents a novel modified electrode for an amperometric hydrazine sensor based on multi-walled carbon nanotubes (MWCNTs) modified with lignosulfonate (LS) and decorated with palladium nanoparticles (NPds). The MWCNT/LS/NPd hybrid was characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The electrochemical properties of the electrode material were evaluated using cyclic voltammetry and chronoamperometry. The results showed that GC/MWCNT/LS/NPd possesses potent electrocatalytic properties towards the electro-oxidation of hydrazine. The electrode demonstrated exceptional electrocatalytic activity coupled with a considerable sensitivity of 0.166 μA μM-1 cm-2. The response was linear from 3.0 to 100 µM L-1 and 100 to 10,000 µM L-1, and the LOD was quantified to 0.80 µM L-1. The efficacy of the modified electrode as an electrochemical sensor was corroborated in a study of hydrazine determination in water samples.

Porous palladium-poly(3,4-ethylenedioxythiophene)-coated carbon microspheres/graphene nanoplatelet-modified electrode for flow-based-amperometric hydrazine sensor

A highly stable flow-injection amperometric hydrazine sensor was developed based on a glassy carbon electrode modified with palladium-poly(3,4-ethylene dioxythiophene) coated on carbon microspheres/graphene nanoplatelets (Pd-PEDOT@CM/GNP/GCE). The Pd-PEDOT@CM/GNP composite was characterized by scanning electron microscopy and energy-dispersive x-ray analysis (SEM/EDX). The modified GCE was electrochemically characterized using cyclic voltammetry and chronoamperometry. The electrocatalytic activity of the Pd-PEDOT@CM/GNP/GCE toward hydrazine oxidation was significantly better than the activity of a bare GCE, a CM/GCE, a GNP/GCE, a Pd-PEDOT/GCE, and a Pd-PEDOT@CM/GCE. The sensor operated best at a low working potential of + 0.10 V (vs. Ag/AgCl). Under optimal conditions, sensitivity toward hydrazine detection and operational stability (601 injections/one electrode preparation) were excellent. The response was linear from 1.0 to 100 μmol L^-1 and from 100 to 5000 μmol L^-1 with a detection limit of 0.28 ± 0.02 μmol L^-1 and high sensitivity of 0.200 μA μM^-1 cm^-2. The sensor showed good repeatability (relative standard deviation (RSD) < 1.4%, n = 15), reproducibility (RSD < 2.7%, n = 6), and anti-interference characteristics toward hydrazine detection. The feasibility of the electrochemical sensor was proved by the successful determination of hydrazine in water samples, and the results were in good agreement with those obtained from spectrophotometric analysis. Graphical abstract.