Study and control of the crystalline orientations in MoS2/TiO2 and MoS2/TiO2:H heterojunctions and their effects on its physicochemical properties

• Grant number: 19/00757-0
• Support type: Scholarships in Brazil - Post-Doctorate
• Effective date (Start): July 01, 2019
• Effective date (End): June 30, 2021
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Fernando Alvarez
• Grantee: Fernando Graniero Echeverrigaray
• Home Institution: Instituto de Física Gleb Wataghin (IFGW). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 12/10127-5 - Research and development of nanostructured materials for electronic and surface physics applications, AP.TEM

Abstract

The performance of electronic and mechanical devices that work continuously or intermittent is impaired by inherent process of energy losses associated with the system. This energy dissipation can be minimized by mastering the atomic-molecular interactions (due to chemical bonds and van der Waals forces) that form the crystalline structure in devices such as nanostructured heterojunctions. These dissipative processes basically depend on the crystalline structure of the materials and mastering its atomic bonding forming is a fundamental step for developing nanostructures heterojunctions for several applications.The project proposes to study the nanoscopic aspects intervening in the formation of atomic interfacial interactions in heterojunctions constituted by MoS2/TiO2 and MoS2/TiO2 nano-layers obtained by Ion Beam Deposition (IBAD) and sputtering techniques. The aims of the project focus on the control of the morphology of heterojunctions (stacking structure), nanofriction and absorption optical gap optical transmission in the ultraviolet-visible UV-VIS ranges for different crystallographic orientations of the multilayer systems. The project contemplates incorporating of the study of the friction properties due to the fact that the electronic structure of the material surface influences the properties related to dissipative forces at the nanoscopic level. As an innovative exploration and based on the importance of the electronic optical gap of TiO2 and passivation surface properties of the material, the project contemplates studies of hydrogen doping. The effect of hydrogen is the modification of the absorption coefficient (optical gap), influencing the Nano friction and photocatalytic properties of these materials. Combining the doping with H of the TiO2 and the control of the interface properties of the crystalline orientation and atomic bonds, the research focus to obtain a family of new materials with potential applications in optoelectronics devices (e.g., solar energy and catalysis) and mechanical devices (e.g., nanoscopic gadgets where low friction is fundamental). (AU)