Theoretical investigation of the electronic spectrum of polyoxometalates: assessment and optimization of their photocatalytic properties

• Grant number: 24/07905-3
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: October 01, 2024
• End date: February 29, 2028
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
• Principal Investigator: Roberto Luiz Andrade Haiduke
• Grantee: Eduardo Orlando Bartaquim
• Host Institution: Instituto de Química de São Carlos (IQSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

Polyoxometalates (POMs) are a class of materials with a wide structural diversity and unique properties, such as the ability to act as both a Lewis acid and a Lewis base. POMs have a variety of applications, including electro- and photocatalysis for CO2 reduction and organic pollutant degradation. However, currently available POMs absorb mostly in the ultraviolet region, which accounts for only 5 % of solar energy. As a result, it is very important to develop POMs that absorb efficiently in the visible region of the solar spectrum. In this scenario, time-dependent density functional theory (TD-DFT) could be useful. TD-DFT is a computational modeling approach used to describe, among other characteristics, the electronic transition spectrum of quantum systems. Nevertheless, due to the usage of approximate terms for exchange and correlation (XC), TD-DFT has shortcomings, including an inaccurate description of charge transfer processes and Rydberg excited states. An alternative to dealing with the problem is the use of range-separated hybrids (RSHs) functionals, especially QTP functionals. Although quite important, there are currently very few studies in the literature that describe the electronic structure of polyoxometalates. The goal of this research is to describe the electronic structure of polyoxometalates in general, such as polyoxoniobates, polyoxovanadates, polyoxomolybdates, polyoxotantalates, and polyoxotungstates, among others. Furthermore, this study aims to investigate the effect of changing the heteroatom and dopants on the electronic structure of POMs. Hence, the usage of QTP functionals will be an important aspect of this research.