First-principles Density Functional Study of Iodine Molecule Adsorption on Stable CuS Surfaces

The present work investigated the adsorption of gaseous iodine molecules (I2) on stable CuS surface, which has demonstrated excellent performance as an adsorbent for I2 removal, with first-principles density functional theory (DFT). In this work, a pair of asymmetric surfaces (marked as slab1 and slab2) formed by breaking the weakest bond along (0 0 1) direction are chosen to present CuS surfaces. The findings indicate that the adsorption of I2 molecules on the pristine CuS(0 0 1) surface is relatively weak, while surface defects significantly enhance the binding strength of I2. In particular, S-vacancy CuS(0 0 1) surfaces exhibit considerably higher adsorption energy for I2 compared to Cu-vacancy surfaces. We found that the hollow and Cu-top sites are typically the dominant adsorption sites, and the initial orientation of I2 relative to the surface also influences the adsorption performance.