Surface Properties of ZnS Nanoparticles: A Combined DFT and Experimental Study

Carbon monoxide adsorption on nanosize ZnS has been investigated by FTIR spectroscopy and periodic DFT calculations. FTIR experiments show that CO adsorption on the zinc sulfide nanoparticles gives rise to a single main ν(CO) band indicating that the majority of the exposed sites are on the same surface. Computed adsorption energies (−0.244/–0.207 eV for the low and high coverage, respectively) and stretching frequencies (2182/2172 cm–1) of CO adsorbed at the most stable (110) ZnS surface are in excellent agreement with observations (ν(CO) = 2190/2168 cm–1). CO is weakly bound to the Zn2+ Lewis acid surface site mainly through electrostatic interaction and a small contribution from σ donation. The strength of surface Lewis sites in ZnS is lower with respect to ZnO.