Self-supported Co3O4 nanoneedle arrays decorated with PPy via chemical vapor phase polymerization for high-performance detection of trace Pb2+

Abstract

Highly ordered three-dimensional (3D) polypyrrole (PPy) coated cobalt oxide (Co₃O₄) nanoneedle arrays (NAs) anchored on Cu foams (Co₃O₄ NAs@PPy) are fabricated for electrochemical sensors to detect trace lead ions (Pb²⁺). The 3D hybrid Co₃O₄ NAs@PPy is synthesized via a hydrothermal method followed by a chemical vapor phase polymerization process. Free-standing Co₃O₄ NAs@PPy can be directly utilized as a 3D electrochemical working electrode without being decorated onto a working electrode like Au and glassy carbon electrodes. In the mean time, the simultaneous incorporation of PPy, Co₃O₄ and Cu foams creates a platform with significantly improved electrochemical properties and excellent sensitivity for a large specific surface area, eminent adsorption capacity and high conductivity. Square wave anodic stripping voltammetry (SWASV) is carried out to observe the electrochemical behavior of the Co₃O₄ NAs@PPy electrode. Under the optimum conditions, a linear range between the currents and the concentrations of Pb²⁺ from 0.024 to 0.48 μM with a high sensitivity of 85.5 μA μM⁻¹ was obtained. The limit of detection can reach 0.58 nM. The results confirmed that the modified electrode is a good candidate for Pb²⁺ detection sensors with excellent reproducibility, stability and lower detection limit. In addition, the developed method was successfully applied to determine Pb²⁺ in real water samples with satisfactory results.