Exploring urinary VOC adsorption on Fe- and Co-adsorbed phosphorene via DFT and thermodynamic analysis

Exploring the adsorption of toxic substances on two-dimensional (2D) materials is crucial for developing efficient sensing platforms. Herein, the adsorption of three volatile organic compounds (VOCs), namely anisole, furan, and thiophene, on pristine and Fe- and Co-adsorbed phosphorene was systematically investigated using density functional theory (DFT) calculations, ab initio molecular dynamics (AIMD) simulations, and thermodynamic analysis. Fe and Co atoms exhibit strong interactions with phosphorene, with adsorption energies of −1.96 and − 2.28 eV/atom, respectively. The adsorption of these transition-metal atoms substantially modifies the electronic and magnetic properties of phosphorene, reducing its band gap to 0.20 eV for Fe-adsorbed phosphorene and 0.33 eV for Co-adsorbed phosphorene, while inducing total magnetic moments of 3.26 and − 1.08 μ B , respectively. AIMD simulations further confirm the thermal stability of the Fe- and Co-adsorbed systems. In contrast to the weak physisorption of the three VOCs on pristine phosphorene, strong chemisorption occurs on the transition-metal-adsorbed systems due to enhanced interactions between the Fe/Co centers and the VOC molecules. On Fe-adsorbed phosphorene, the calculated adsorption energies are −1.75, −1.32, and − 1.47 eV for anisole, furan, and thiophene, respectively. The formation of strong Fe O and Fe S interactions is further supported by ICOHP values of 0.159, 0.146, and 0.362 for Fe O in anisole, Fe O in furan, and Fe S in thiophene, respectively. Charge-density redistribution and charge transfer upon VOC adsorption further demonstrate strong adsorbate–substrate interactions. COHP analysis reveals predominantly weak ionic bonding for anisole and furan, whereas thiophene exhibits mixed covalent–ionic character. Thermodynamic analysis indicates that adsorption of these VOCs on Fe-adsorbed phosphorene is spontaneous at elevated temperatures, highlighting the potential of transition-metal-adsorbed phosphorene for VOC sensing applications.