Ag-Loaded WS₂-Based Pb²⁺ Ion Detection in Water

Abstract

The prompt detection of aqueous pollutants, with both high speed and precision, holds great significance due to the substantial threats they impose on human well-being and the environment. Lead and its derivatives exhibit a high level of toxicity, capable of inducing various ailments. Nevertheless, existing lead detection systems are suffered from several drawbacks, including sluggish response times, elevated cost, and a lack of mobility. Here, a sensor for highly sensitive, selective, and rapid detection of the trace amount of toxic lead (Pb <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{{2}+}{)}$ </tex-math></inline-formula> ions was successfully developed using tungsten disulfide (WS <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{2}}{)}$ </tex-math></inline-formula> functionalized interdigitated electrodes (IDEs). Pristine and silver (Ag)-loaded WS2 were synthesized via the facile hydrothermal method. A series of characterizations are performed to investigate the crystal structure, surface morphology, and elemental composition of the synthesized materials. When exposed to 10 parts per billion (ppb) of Pb <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{{2}+}$ </tex-math></inline-formula> ion solution, pristine WS2 nanorods exhibited a 1.31-mA change in current, while at the loading of 1% and 2% Ag, further enhancements in Pb <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{{2}+}$ </tex-math></inline-formula> ion sensitivity were observed. However, further increasing the Ag (4 wt%) loading on WS2 nanorods reduced the sensing response. The developed sensor was characterized by an excellent sensitivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$819 \mu \text{A}$ </tex-math></inline-formula> /ppb and an impressive detection limit of 75 ppt. Additionally, the sensor showed a rapid response time of less than 5 s, rendering its suitability for real-time heavy metal ion detection applications. The outstanding performance of WS2-based sensors makes them a compelling choice for practical application in monitoring environmental quality and detecting toxic metals.