Chromium(VI) sensor based on catalytic reduction using the nanoporous layer of poly(aminopyrimidyl- terthiophene) and AuNi composite

Abstract

Nanoporous layer of Ni-dealloyed AuNi composited with a functionalized conductive polymer (poly[3′-(2-aminopyrimidyl)-2,2′:5′,2′′-terthiophene] (pPAT)) was electrochemically synthesized, characterized, and applied for a Cr(VI) sensor. At first, we examined the voltammetric response of different kinds of Au alloys (AuCu, AuCo, and AuNi) for the Cr(VI) reduction reaction, where porous AuNi alloy reveals the best performance to the catalytic reduction. Hence, the final sensor was prepared through composition of AuNi and pPAT followed by Ni dealloying, which enhances the catalytic performance through increasing the electrochemical active area by about 12.6 times. The sensor revealed a well-behavioural catalytic Cr(VI) reduction at around +0.5 V. The surface analysis and electrochemical characterization were performed for each sensor layer to elucidate morphology and surface composition. Experimental parameters affecting the Cr(VI) analysis were optimized and the interference effects were also investigated. The dynamic range of square wave voltammetry was between 1.0 ppb and 10.0 ppm Cr(VI) with the detection limit of 0.25 ± 0.05 ppb (n = 3). The reliability of proposed sensor was evaluated by analysing real water samples and standard reference material.