Synergetic interplay between metal (Pt) and nonmetal (C) species in codoped TiO2: A DFT+U study

Abstract

The structural, energetic, magnetic and electronic properties of Pt-C-doped and Pt/C-codoped TiO2 have been studied using first-principle calculations to elucidate the effect of the metal-nonmetal interactions. Compared with other non-metals, C-doping induces the formation of complex structures on titania. From the analysis of the electronic structures of the C-doping system, band gap narrowing as well as the formation of localized gap states are observed in it. The calculated results are in agreement with the experimental absorptions observed in the UV-visible diffuse reflectance spectroscopy spectra. Based on our results, the main findings relating to Pt/C codoping are the formation of highly symmetric coordination-like compounds and the formation of impurity states in the band gap that could be propitious for the separation of photoexcited electron-hole pairs. Is especially remarkable the case of Pt/C@Ti-codoped TiO2 which could be the most effective for the redox reaction of H2O to produce H2 and O2 because it presents the greatest narrowing of the band gap, the lower shift of the conduction band and it is the only one that favorably modifies the position of valence band. All are necessary conditions for the reaction mentioned.