Simulation Study on the Adsorption Effect of Modified Black Phosphorus on Volatile Organic Compounds

Context As an emerging two-dimensional material, black phosphorus (BP) shows unique advantages in air purification and gas adsorption due to its special structure and high surface area. To improve pristine BP's limited adsorption, this study uses density functional theory (DFT) to simulate adsorption effects and structural changes of BP doped with ten elements (such as N and As) on volatile organic compounds (VOCs). Results show that during formaldehyde adsorption on bilayer BP, the R-site with larger contact area has the smallest adsorption energy, indicating chemical adsorption and best performance, with structural changes in both BP and formaldehyde. Doping greatly improves BP's adsorption, with Al-doped BP at the R-site showing nearly three times better formaldehyde adsorption than intrinsic BP. Analysis of electronic properties and charge transfer shows that electron state reconstruction in doped bilayer BP strengthens interaction with polar molecules, enhancing adsorption ability. The doped BP system adsorbs oxygen-containing VOCs (e.g., acetone, acetaldehyde) better than non-polar molecules (e.g., methane, benzene). These findings help screen and develop high-performance 2D adsorption materials. Methods All calculations used DFT with GGA-PBE and LDA. A plane-wave basis set (480 eV cutoff) and ultrasoft pseudopotentials were used. The Brillouin zone was sampled with a 2×2×2 k-point grid. Adsorption energies were calculated, and electronic properties like charge density and Mulliken charge transfer were analyzed. All simulations used the CASTEP module in Materials Studio.