Electronic and Optoelectronic Properties of Heavy Metal-Adsorbed h-BAs Monolayer: A DFT-Based Sensor Study

Detection of heavy metals in water and air is imperative for a clean environment and assuring human health. In this study, we explore the potential of a twodimensional (2D) hexagonal boron arsenide (h-BAs) monolayer as a highly effective sensing material for key heavy metals, like lead (Pb), mercury (Hg), cadmium (Cd), chromium (Cr), nickel <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\text{Ni})$</tex>, antimony (Sb), and selenium (Se). Through state-of-theart density functional theory, the study evaluates key sensing properties of these metals: formation and adsorption energies, bandgap, electrical conductivity, and absorption coefficient on the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$h$</tex>-BAs monolayer and its two terminal I-V characteristics. Notably, this study examines, negative differential resistance (NDR) which is observed in the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$I-V$</tex> characteristics of heavy metal-adsorbed h-BAs at higher voltages (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1.75 \mathrm{V}-2 \mathrm{V}$</tex>), marking a significant advancement for sensing applications. For a more realistic simulation, the study also considers the adsorption of heavy metals in the presence of water molecules, which lowers the threshold voltage. The study shows the high potential of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$h$</tex> BAs 2D material for key heavy metal detection.