Nanosized ZnIn₂S₄ supported on facet-engineered CeO₂ nanorods for efficient gaseous elemental mercury immobilization

Nanosized ZnIn₂S₄ supported on facet-engineered CeO₂ nanorods were prepared by solvothermal method to effectively capture gaseous elemental mercury from flue gas. The CeO₂/ZnIn₂S₄ sorbent exhibited excellent mercury removal performance (>90%) in a wide temperature range from 60 to 240 ℃ and showed much higher mercury adsorption capacity than pure CeO₂ due to the enlarged specific surface area and abundant active oxygen and sulfur sites on the surface. It was found that CeO₂/ZnIn₂S₄ has good resistance to SO₂, NO and H₂O. At the optimal 120 ℃, the equilibrium Hg⁰ adsorption capacity of CeO₂/ZnIn₂S₄ can reach 19.172 mg/g, which is superior to the reported series of benchmark materials. X-ray photoelectron spectroscopy and temperature programmed desorption of mercury confirmed that the adsorbed mercury existed on the surface as HgO and HgS, indicating that catalytic oxidation and chemisorption occurred on the surface of the adsorbent. The adsorption energy of Hg⁰ on the CeO₂ (110) and ZnIn₂S₄ (110) surfaces calculated with density functional theory (DFT), further confirms that the surface activated oxygen and sulfur sites are the most stable adsorption sites. Furthermore, the good regeneration capability of CeO₂/ZnIn₂S₄ makes it more promising for Hg⁰ capture in practical applications.