First Principles Calculation of Hydroxyl and Sulfur Ions Adsorbed on Te (001) Surface

This study employed first−principles calculations based on density functional theory (DFT) to systematically investigate the adsorption mechanisms and synergistic leaching effects of hydroxyl ions (OH⁻) and sulfide ions (S²⁻) on the tellurium (Te) (001) surface. A Te(001) surface model was constructed, and adsorption energies, density of states (DOS), and Mulliken charges were analyzed to elucidate the adsorption behaviors and interaction mechanisms. The result sreveal that both OH⁻ and S²⁻ exhibit stable chemisorption on the Te(001) surface, with the top site showing the most stable configurations (adsorption energies: −1.386 eV for OH⁻ and −1.838 eV for S²⁻). The introduction of S²⁻ significantly enhances the adsorption stability of OH⁻, as evidenced by a further decreased adsorption energy (−2.126 eV) in the mixed system, confirming their synergistic interaction. DOS analysis demonstrates resonance peaks near the Fermi level between the p orbitals of O/S and Te, indicating the formation of O–Te and S–Te chemical bonds. Mulliken charge analysis shows that S²⁻ promotes charge transfer on the Te surface, increasing the bond populations of O–Te (from 0.12 to 0.16) and S–Te (from 0.36 to 0.48), which validates the electronic synergy. The experimental results show that the addition of S²⁻ significantly enhances the adsorption capacity of OH⁻ on the surface of tellurium. After the addition of S²⁻, the leaching rate of tellurium increases from 43.97% to 66.13%, which confirms the practical application value of the synergistic effect. The theoretical calculation explains that the increase of tellurium leaching rate is due to the synergistic leaching action of S²⁻ at the microscopic level. This study reveals the surface adsorption mechanism and the synergistic leaching effect of the systems of NaOH, Na₂S, and the mixture of NaOH and Na₂S during the leaching process of tellurium through density functional theory. It clarifies the mechanism of the promoting effect of S²⁻ on the adsorption of OH⁻, providing a theoretical basis for the optimization of the high−efficiency leaching and extraction process of tellurium.