WS₂ Nanosheet-Based Sensors for Efficient Detection and Removal of Potentially Toxic Elements: A DFT Investigation

Abstract

This study presents a computational approach for designing nanosensors based on two-dimensional tungsten disulfide (WS2) monolayers for detecting potentially toxic elements (PTEs), including silver (Ag), arsenic (As), chromium (Cr), cadmium (Cd), mercury (Hg), and lead (Pb). Using first-principles density functional theory (DFT) calculations, the sensing performance of WS2-based materials was assessed in both atmospheric and aqueous conditions. To enhance the inherently weak adsorption and limited electronic interaction of pristine WS2 with PTEs, its carrier concentration was modulated by introducing sulfur vacancies (WS2–Sv) and doping with low concentrations (1.33%) of carbon (WS2–C), phosphorus (WS2–P), oxygen (WS2–O), and silicon (WS2–Si). These modifications significantly improved the material’s sensitivity and selectivity toward the targeted PTEs. Beyond atmospheric detection, the doped WS2 sensor systems demonstrated strong potential for application in aqueous environments, indicating their suitability for water purification. The sensing capabilities of WS2 were further substantiated by measurable alterations in electronic and charge transfer characteristics, as revealed through analyses of the density of states, work function, electrostatic potential profiles, and Bader charge analysis. To enable quantitative detection of PTEs under varying pressure, temperature, and surface coverage conditions, a statistical thermodynamics framework based on the Langmuir adsorption model was applied. Additionally, selective detection of PTEs was evaluated using nonequilibrium Green’s Functions (NEGF) formalism. Collectively, these findings highlight WS2-based nanosensors as a promising platform for the sensitive and selective adsorption and detection of toxic elements in diverse environmental settings.