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.