In Silico Study of Interactions between the Methylene Blue Molecule and the (TiO₂)₂₀ Cluster by Means of DFT Calculations

In this work, the (TiO2)(20) cluster is proposed to adsorb the methylene blue (BM) dye; thus, the quantum parameters to explain the adsorption process are calculated by means of density functional theory calculations. Eight possible configurations are obtained and labeled from M1 to M8. According to the adsorption energy values, they reveal physisorption for at least two cases, and for the rest of the systems, they exhibit chemisorption. The preferential positions that lead to good adsorption for the BM dye are parallel to the semiconductor cluster; however, when one end of the BM dye formed by hydrogen atoms is interacting with the cluster, a weak chemical interaction is reached. The chemical interactions for M4 and M5 systems generate considerable increases of their electronic gap values (E-g) with respect to the rest, and this effect is explained based on iso-surfaces of frontier orbitals and electronic charge transference. The chemical interactions between these chemical species are stable under vibrational and thermal criteria. This semiconductor cluster arises as a good candidate to adsorb some dyes like BM.