Rapid‐Response and Portable Lead Ion Sensor Using Co/Pt/Si Schottky Heterojunction Without Reference Electrode

Abstract

Lead ions (Pb <sup>2+</sup>) are classified as highly toxic heavy metals that pose substantial threats to both human health and environmental integrity. Consequently, the sensitive detection of Pb <sup>2+</sup>, particularly at low concentrations, is imperative for the purposes of environmental surveillance and safeguarding public health. Here, we introduce a Co/Pt/Si Schottky heterostructure for a rapid, portable Pb <sup>2+</sup> detection sensor. One electrode of the heterojunction serves as a Pb <sup>2+</sup> probe, and sensor processing circuits are integrated. The Co/Pt thin films were deposited via magnetron sputtering on a Si(100) substrate, followed by heterojunction fabrication using semiconductor process technology. The sensor is functionalized with a glutathione‐modified gold electrode, leveraging the sulfur‐donor properties of cysteine in glutathione and the electron‐acceptor behavior of Pb <sup>2+</sup> ions. This interaction modulates the gold electrode's surface potential, altering the current‐voltage rectification of the Co/Pt/Si heterojunction. A two‐terminal configuration enables current signal readout without reference electrodes. The sensor demonstrates a linear response to Pb <sup>2+ </sup>concentrations ranging from 1 × 10 <sup>‐8</sup> to 1 × 10 <sup>‐3</sup> mol/L, with high selectivity attributed to the affinity of glutathione for Pb <sup>2+</sup>. Its key benefits are the simplicity of its fabrication process and its portability, which are enhanced by the integration of measurement circuitry. This makes the sensor a promising candidate for rapid, on‐site detection of heavy metal ions in applications related to health and environmental monitoring.