A highly specific heterostructure composed of N-doped TiO₂ anatase nanoparticles and double layer Au for detection of thiophene molecule: A DFT study

Abstract

The adsorption of thiophene molecule on the pristine, N-doped and Cu/N codoped TiO₂-supported Au overlayers has been studied using density functional theory calculations, taking into consideration the effects of van der Waals interaction. Thiophene molecule can be adsorbed on both the Au and five-fold coordinated titanium sites of TiO₂ supported Au overlayers. Various adsorption configurations of thiophene over the considered TiO₂ supported Au overlayers are discussed. It is found that with Cu/N codoped nanoparticle as an adsorbent, the adsorption configuration is more stable and consequently the adsorption process is more energetically favorable. The adsorption of thiophene molecule on the N-doped TiO₂ supported Au overlayers is more energetically favorable than the adsorption on the undoped ones. On the Cu/N codoped nanoparticle, the adsorption process is more strongly favored. Thus, Cu/N-codoped system can interact with thiophene molecule more efficiently. The considerable overlaps between the PDOSs of the sulfur and titanium atoms indicate chemical bond forms between these two atoms. These chemical bonds confirm chemisorption of thiophene on the TiO₂ supported Au overlayers. After the adsorption process, the HOMOs are mainly distributed over the adsorbed thiophene molecule. The charge analysis based on Mulliken charges reveals that charge is transferred from the thiophene molecule to the TiO₂ supported Au. This study not only suggests a theoretical basis for adsorption behaviors of thiophene on the TiO₂-supported Au overlayers, but also provides an efficient strategy to design and improve highly efficient sensor devices for thiophene detection.