Novel nitrite sensing using a palladium-polyphenosafranine nano-composite.

A novel palladium-polyphenosafranine nano-composite (PPS-Pd) was synthesized by electrochemical co-deposition at a glassy carbon electrode (GCE) for fabrication of a nitrite sensor, PPS-Pd/GCE. This PPS-Pd film was characterized by X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microanalysis (SEM). It was found that the PPS-Pd nano-composite consisted of Pd nanoparticles smaller than 10 nm in diameter which stick together due to the polymer, forming a Pd-embedded PPS layer structure. The sensing ability was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and differential pulse amperometry (DPA). The PPS-Pd/GCE had excellent catalytic activity toward the oxidation of nitrite: high current sensitivity of 0.365 A/M cm(-2), good reproducibility, good stability and fast response. In neutral solutions, a linear concentration range of 1.0 x 10(-6) to 1.1 x 10(-3) M (R(2) = 0.999) with the detection limit (s/n = 3) of 3 x 10(-7) M nitrite was obtained for DPV determination.