A first-principles investigation of Cr adsorption on C8 and B4N4 nanocages in aqueous mediums

Abstract

Heavy metal removal from polluted environments is one of the vital research areas for better and healthier living. In this research, C₈ and B₄N₄ nanocage-like quantum dots are investigated for heavy metal (Cr) removal applications via density functional theory calculations. The adsorption of up to two Cr atoms has been studied in both air and a water medium. The adsorption of Cr atoms results in significant structural deformation of the adsorbents with a high adsorption energy of −8.74 and −5.77 eV for C₈ and B₄N₄ nanostructures, respectively, which is further increased with an increasing number of Cr atoms. All adsorbents and complex structures showed real vibrational frequencies. Mulliken charge and electrostatic potential analysis reveal a significant charge transfer between adsorbate–adsorbent. The adsorption process causes a decrease in the energy gap of the adsorbents. All the reactions in this study were spontaneous and thermodynamically ordered. QTAIM analysis verifies that the interactions of the adsorbents with Cr atoms are strong partial covalent. The study's findings make C₈ and B₄N₄ nanostructures potential candidates for Cr-detection and removal applications.