Catalyst nature influence on fluoroquinolone adsorption

Abstract

In this work, the Norfloxacin (NFX) adsorption on two types of catalysts: ZnO (Wurtzite) and TiO₂ (Anatase) was studied using the Vienna Ab Initio Simulation Package (VASP) program, which is based on the formalism of Density Functional Theory (DFT). The two ZnO polar surfaces were modeled, one with O exposed (000-1) called “ZnO-O” and the other with Zn exposed (0001) called “ZnO-Zn”. The aim is to evaluate the differences between ZnO surfaces and compare them with the Anatase surface (TiO₂-A). The adsorbate-substrate interaction was analyzed by the atomic charges and the bond order using the DDEC6 method. Density atomic charge differences were also carried out. The adsorption energies (E_ads) obtained were exothermic, being the highest magnitude the situations in which the molecule adsorbs on ZnO. In the case of NFX on ZnO-O, a dissociative adsorption occurs with the loss of one hydrogen from the molecule and one hydroxyl formation on the surface. While, for ZnO-Zn and TiO₂-A surfaces the adsorption is not dissociative.