Ab initio calculation of magnetic properties in B, Al, C, Si, N, P and As-doped rutile TiO2

The ferromagnetic (FM) ordering in rutile TiO2 has been theoretically studied by substituting different [Formula: see text]-block elements (B, Al, C, Si, N, P and As) doped at oxygen site (B[Formula: see text], Al[Formula: see text], C[Formula: see text], Si[Formula: see text], N[Formula: see text], P[Formula: see text] and As[Formula: see text]) as well as at titanium site. Ab initio calculations in the frame work of density functional theory indicates that the [Formula: see text]-block elements (B, C, Al, Si, N, P and As) when substituting the oxygen site give significant amount of magnetic moment, but induce zero magnetic moment in case of substitution at Ti site. Spin–spin interaction for (Ti[Formula: see text]O[Formula: see text]X)2 with X = B, Al, C, Si, N, P and As system has also been studied with two different doping distances. Among all the possibilities, carbon substitution at oxygen site (C[Formula: see text]) results the most stable FM ordering in rutile TiO2.

Theoretical investigation of the adsorption behaviors of CO and CO2 molecules on the nitrogen-doped TiO2 anatase nanoparticles: Insights from DFT computations

Over the past years, an interest has arisen in resolving the problems of the increased carbon monoxide and carbon dioxide emissions, leading to the serious air pollution and many detrimental effects. A convenient solution would be a process that could utilize metal oxide nanoparticles such as TiO2 to control the concentration of atmospheric pollutants. The chemisorption of CO and CO2 molecules over the semiconductor titanium dioxide (TiO[Formula: see text] is such a process. In this way, density functional theory (DFT) calculations were performed to investigate CO and CO2 adsorptions on undoped and N-doped TiO2 anatase nanoparticles. The supercell approach is conducted to construct the considered nanoparticles and the adsorption of COx molecule was simulated by use of these chosen nanoparticles. By including van der Waals (vdW) interactions between COx molecule and TiO2 nanoparticle, we found that both CO and CO2 molecules can bind strongly to the N-doped nanoparticles. The adsorption on the five-fold coordinated titanium site of TiO2 nanoparticles including the bond lengths, bond angles, adsorption energies, density of states (DOSs), Mulliken population analysis and molecular orbitals has been broadly studied in this work. Based on the obtained results, it can be concluded that the adsorption on the N-doped nanoparticle is more energetically favorable than the adsorption on the pristine one, representing the higher tendency of N-doped nanoparticles for COx detention, compared to the undoped ones. Therefore, the results indicate that the N-doped TiO2 would be an ideal COx gas sensor in the environment.