Theoretical study on the electronic structure properties of a PbS quantum dot adsorbed on TiO2 substrates and their role on solid-state devices

• Published in: Computational and theoretical chemistry 2017-01, Vol.1100, p.83-90
• Main Authors: Díaz Rodríguez, T.G., Reyes-Nava, J.A., Pacio, M., Juárez, H., Muñiz, Jesús
• Format: Article
• Language: English
• Subjects: DFT; Energy storage; Molecular Dynamics; PbS@TiO2; Quantum dot; Renewable energy
• ISSN: 2210-271X
• DOI: 10.1016/j.comptc.2016.12.013

[Display omitted] •A combined DFT and MD study was performed on a series of PbS@TiO2 nanocomposites.•A TiO2 amorphous phase was identified from the quenching performed with MD.•The calculated band gap of PbS@TiO2 appears in the range of visible light.•The PbS QD is adsorbed on the TiO2 substrate with an electrostatic-type attraction. A theoretical study was carried out for the first time in a series of two nanocomposite semiconducting systems (PbS)4@(TiO2)38. We stabilized two structures of TiO2 using a simulated annealing procedure with Molecular Dynamics as a first approach and the second model was optimized at the PBE level of theory, as benchmarking. An amorphous and anatase structures were found for both methodologies, respectively. We adopted the cubic structure of the (PbS)4 quantum dot as suggested by experimental data. The DOS of the isolated systems were assessed and also those of the composites (PbS)4@(TiO2)38. Adsorption energies on both systems were estimated and an attraction with a certain degree of covalency was found for the (PbS)4 at the TiO2 anatase model system. A weaker interaction of the electrostatic-type was found with the TiO2 amorphous configuration. In both systems, the attraction is favored in STi bond pairs. The DOS for the composite systems presents a different nature for the amorphous and anatase cases that is evidenced in the size of the band gaps. The (PbS)4@(TiO2)38 anatase composite systems results in a more favorable electronic structure that may readily provide fundamental data to develop and design photocatalytic devices for hydrogen production, energy storage and photovoltaic applications.