The mechanism of carcinogenic heavy metal adsorption on a new monolayer AlP₅

A new monolayer AlP₅ is proposed for the detection of carcinogenic heavy metals such as As, Hg and Cd in water. Based on the first-principles calculations, AlP₅ is predicted to be dynamically, mechanically, and thermodynamically stable. AlP₅ is a quasi-direct semiconductor with an indirect/direct band gap of 0.92/0.95 eV, and strain and layer stacking order can be used to tune its band gap. The electronic properties of AlP₅ adsorbed by heavy metals in vacuum and water environments are analyzed to investigate the sensing behaviors. The results indicate that the presence of H₂O molecules increases the adsorption energy of As, Hg and Cd on the surface of AlP₅. The adsorption capacity of AlP₅ for heavy metals in vacuum and water environments is As > Cd > Hg. The significant changes in band structure, charge transfer and density of states (DOS) indicate that AlP₅ exhibits strong interactions for As, Cd and Hg. Therefore, the monolayer AlP₅ is suitable for detecting and adsorbing heavy metals As, Cd and Hg.