Nanocomposites based on quasi-networked AuPtCo ternary alloy nanoparticles and decorated with poly-L-cysteine film for the electrocatalytic application of hydroquinone sensing.

A mildly one-pot method is developed for the synthesis of quasi-networked AuPtCo ternary alloy nanoparticles (TANPs) at room temperature through the co-reduction of AuCl, PtCl and Co with hydrazine hydrate. Characterizations of XRD, XPS, HRTEM, EDS and SAED successfully reveal the crystal structure, composition, valence and morphology of AuPtCo TANPs, respectively. The glassy carbon electrode (GCE) modified by AuPtCo TANPs with good dispersion and multi-density surface defects occupies the optimal electrochemical active surface area (ECSA). After the coated poly-L-cysteine (P-L-Cys) film on the AuPtCo/GCE surface, the morphology, element mapping and surface roughness of the P-L-Cys/AuPtCo/GCE are investigated via FESEM and AFM to verify continuous electrode modification processes. The electrochemical behaviors of the composite electrode for hydroquinone (HQ) are evaluated by cyclic voltammetry (CV) with interfacial properties of adsorption and diffusion. Differential pulse voltammetry (DPV) for HQ electrochemical sensing at 0.10 V (vs. SCE) exhibits two linear response ranges from 0.1 to 30 and 30-200 μM, respectively. A low detection limit (S/N = 3) of 0.045 μM is obtained with a sensitivity of 4.247 μA μM·cm. The resulting P-L-Cys/AuPtCo/GCE also presents ascendant selectivity, repeatability, reproducibility and stability. In addition, the established method is applied to the assessment of the HQ level in real water samples (mineral water, tap water and lake water) with the satisfactory results of spiked recoveries. The sensor may become a promising tool for the trace analysis of the electroactive substance in food or environmental samples.