The effects of subsurface Ov and Tiint of anatase (1 0 1) surface on CO2 conversion: A first-principles study

Abstract

Using the first-principles calculations, we explored the effects of intrinsic subsurface oxygen vacancy and Ti interstitial defects on the adsorption and reduction reaction of CO2 at anatase (1 0 1) surface. Both PBE + U and HSE06 results show that such intrinsic defects have strong selectivity for the CO2 binding to sites near the defects. For the most favorable site, the CO2 adsorption energy can be greatly increased by 0.06 – 0.2 eV relative to the perfect surface. This enhancement is greatly affected by the local structure distortion and the location of the excess electrons. Furthermore, the reduction reactions of CO2 into useful fuels such as HCOOH have also been explored. It is revealed that the energy barrier for the rate-limiting step of CO2 activation can be greatly lowered by the intrinsic defects. These results show the important effects of the defects on the CO2 adsorption and reduction processes.