A novel gas-phase mono and bimetallic clusters decorated Zno nanorods electrochemical sensor for 4-aminophenol detection

4‑aminophenol (pAP) is a typical secondary product obtained in pharmaceuticals preparation that needs to be accurately measured to avoid dangerous collateral effects in drugs. According to European, United States and Chinese Pharmacopoeias authorities the level of pAP in drugs is limited to 50 ppm. Therefore, it is crucial to define suitable methods to fabricate innovative devices for a fast and accurate detection of these molecules. To this purpose, a strategy is presented combining fast detection methods such as Electrochemical Impedance Spectroscopy, Cyclic Voltammetry and Chronoamperometry taking advantage of the nanostructured electrodes' properties. In this work, we propose a simple and novel electrochemical sensor based on nanostructured electrode comprised of ZnO nanorods decorated by bimetallic (AuxPt1−x) Clusters. To finely tune the composition and the size of the metal nanoclusters we used a Laser Ablation Cluster Beam Deposition technique (LACBD) thus obtaining nanoparticle with an average size of 2–3 nm. Different composition in the AuxPt1-x clusters (with x = 0, 0.5, 1) have revealed specific sensing capabilities. In particular, Au/ZnO electrodes did not show a significant improvement respect to the bare ZnO electrode. Conversely, Pt/ZnO electrodes showed a higher sensitivity (12.55 μA/mM cm2) and a limit of detection of 4.1 μM while Au0.5Pt0.5/ZnO electrodes resulted the best combination, exhibiting sensitivity of 14.31 μA/mM cm2 and a limit of detection of 3.6 μM.