文摘
In this work, we reported the highly ordered NiCo2O4 nanoneedle@polypyrrole arrays anchored on three-dimensional graphene (NiCo2O4@PPy/3D graphene) for high-sensitivity detection of trace lead ions (Pb2+). The 3D graphene was prepared by a hydrothermal process and then decorated with NiCo2O4 nanoneedle arrays by another hydrothermal process. This two-step hydrothermal method is simple and mild. Furthermore, the highly conductive PPy was coated on NiCo2O4 via a chemical vapor-phase polymerization to prepare NiCo2O4@PPy/3D graphene. The free-standing NiCo2O4@PPy/3D graphene can be directly utilized as 3D electrochemical working electrode without being decorated onto working electrode like Au and glassy carbon electrode. High conductivity, large specific surface area, short ion diffusion path and excellent adsorption capacity of NiCo2O4@PPy/3D graphene efficiently improved electrochemical property for the detection of Pb2+. Using square-wave anodic stripping voltammetry (SWASV), a linear range between the currents and the concentrations of Pb2+ of 0.0125–0.709 μM with a high sensitivity of 115.621 μA μM−1 was obtained. The limit of detection can reach to 0.2 nM. In addition, the fabricated sensor of Pb2+ also had good selectivity, reproducibility and long-term stability. Finally, NiCo2O4@PPy/3D graphene electrode was utilized for determining Pb2+ in tap water sample using the standard addition method, revealing a promising application for the quantitative detection of certain concentration ranges of Pb2+ in real sample.
