Preadsorbed SO₃ Inhibits Oxygen Atom Activity for Mercury Adsorption on Cu/Mn Doped CeO₂(110) Surface

Abstract

The coadsorption of Hg0 and SO3 on pure and Cu/Mn doped CeO2(110) surfaces were investigated using the Density Functional Theory (DFT) method. A p (2 × 2) supercell periodic slab model with seven atomic layers was constructed to represent the CeO2(110) surface. The results indicated that Hg0 physically adsorbed on the CeO2(110) surface, while Hg0 chemically adsorbed on the Cu/Mn doped CeO2(110) surface, which agree well with the experimental results that Cu and Mn doped CeO2 greatly improved the Hg0 adsorption capacity of the adsorbent. The calculated results suggested that SO3 more easily adsorbs on the above three surfaces than Hg0 due to the higher adsorption energy. The adsorption configurations and electronic structures indicated SO3 reacted with O atoms of the surface to form SO42– species. Hence, SO3 inhibits Hg0 adsorption on the CeO2(110) surface by competing with Hg0 for surface lattice oxygen. In addition, SO3 decreased the activity of the surface O atoms, which directly caused the negative effect on Hg0 adsorption.