Metallic 1T Phase Tungsten Disulfide Microflowers for Trace Level Detection of Hg²⁺ Ions

Electrochemical sensors for mercury ion detection would ideally demonstrate wide linear detection ranges (LDRs), ultratrace sensitivity, and high selectivity. This work presents an electrochemical sensor based on metallic 1T phase tungsten disulfide (WS₂) microflowers for the detection of trace levels of Hg²⁺ ions with wide LDRs, ultratrace sensitivity, and high selectivity. Under optimized conditions, the sensor shows excellent sensitivities for Hg²⁺ with LDRs of 1 nm–1 µm and 0.1–1 mm. In addition to this, the limit of detection of the sensor toward Hg²⁺ is 0.0798 nm or 79.8 pm, which is well below the guideline value recommended by the World Health Organization. The sensor exhibits excellent selectivity for Hg²⁺ against other heavy metal ions including Cu²⁺, Fe³⁺, Ni²⁺, Pb²⁺, Cr³⁺, K⁺, Na⁺, Ag⁺, Sn²⁺, and Cd²⁺. The thus-obtained excellent sensitivity and selectivity with wide LDRs can be attributed to the high conductivity, large surface area microflower structured 1T-WS₂, and the complexation of Hg²⁺ ions with S²⁻. In addition to good repeatability, reproducibility, and stability, this sensor shows the practical feasibility of Hg²⁺ detection in tap water suggesting a promising device for real applications.