Highly sensitive and selective electrochemical detection of Pb(II) in serum via an α-Fe2O3/NiO heterostructure: Evidence from theoretical calculations and adsorption investigation

Abstract The construction of an effective electrochemical sensing interface to achieve highly sensitive and selective determination of heavy metal ions (HMIs) is urgently required, and elucidation of a sensitive mechanism has important guiding significance for developing novel sensing interfaces. In this study, α-Fe2O3/NiO heterostructure nanocomposites are synthesized and used to modify glassy carbon electrodes (GCEs) to construct an electrochemical sensing interface to detect HMIs with high sensitivity and selectivity for Pb(II) detection. Density functional theory (DFT) calculations describe the diffusion energy barrier of Pb atoms at the interface of the α-Fe2O3/NiO heterojunction, which was relatively small compared to other HMIs. This characteristic is conducive to the diffusion of Pb(II) adsorbed on the α-Fe2O3/NiO surface to the surface of the electrode to cause redox reactions, thereby obtaining an increased stripping signal. Considering both experiments and theoretical calculations, the essential reason for the highly sensitive and selective Pb(II) electroanalysis is demonstrated. Additionally, the proposed electrochemical sensor exhibits satisfactory anti-interference performance. Efficacious detection of heavy metals in water and serum shows that this analytical method has strong potential in the analysis of environmental and biological samples.