An electrochemical sensor for nitrobenzene using π-conjugated polymer-embedded nanosilver

Abstract

A novel electrochemical sensing platform for nitrobenzene has been developed using silver nanoparticles (AgNPs) embedded in the poly(amic) acid (PAA) polymer matrix (PAA–AgNPs). PAA was synthesized via the polycondensation reaction of para-phenylenediamine and benzene-1,2,4,5-tetracarboxylic dianhydride. PAA–AgNP nanocomposites were synthesized by the in situ reduction of a silver precursor by the polymer at room temperature in a one-step approach without using an extraneous reducing or capping agent. The composite was subsequently characterized in solution and as a thin film. The X-ray diffraction technique revealed the crystalline nature of the PAA films with the embedded AgNPs. Unlike conventional polymers, the synthesized PAA membrane exhibits significant UV/Vis spectroscopic response. The sequestered nanoparticles also show the characteristic surface plasmon resonance (SPR) peaks confirming the presence of AgNPs. Integrated charge areas were 4.826 mC and 2.176 C for PAA/GC and PAA–AgNPs/GC respectively. The charge at the PAA–AgNP/GC electrode is 451 times greater than that at the PAA/GC electrode suggesting that the AgNP composite exhibits higher electroactivity. When tested as a sensor for nitrobenzene, the PAA–AgNP modified GC electrode showed promising potential as an electrochemical sensor. The electrochemical sensors exhibit a wide linear dynamic range (10–600 μM) with a correlation coefficient of 0.9735, a detection limit of 1.68 μM and a sensitivity of 7.88 μA μM⁻¹. The sensor also exhibited minimal interference effects on structurally-similar nitroaromatic compounds and metal species such as 4-nitroaniline (4-NA), 2-nitrophenol (2-NP), dinitrobenzene (DNB), Pb²⁺ and Cd²⁺.