Polaron modulation mechanism of H2O and CO2 adsorption on PuO2(111) surface

Abstract

The polarons induced by interactions between excess charges and lattice distortions play an important role in surface chemical reactivity of actual oxides. The impacts of electron and hole polarons on H2O and CO2 adsorptions on PuO2(111) surface are investigated by first-principles DFT+U-D3 calculations. Our study reveals that surface and subsurface electron/hole polarons play different roles to H2O and CO2 adsorption. Surface polarons can promote H2O and CO2 adsorption, specifically, electron polarons tend to promote H2O adsorption much more, and hole polarons tend to facilitate CO2 adsorption. We find it interesting that the subsurface electron polaron can promote H2O but depress CO2 adsorption, whereas the subsurface hole polaron play quite an opposite role. Based on a careful study on the electronic and atomic structures of the defective PuO2(111) surfaces, we put forward the inverse modulation mechanism by subsurface electron and hole polarons on H2O and CO2 adsorption, which could shed some light on how to manipulate the molecular adsorption on oxide surfaces.