First-principles studies on facet-dependent photocatalytic properties of BiOI {001} surface

The photocatalytic properties are compared for {001}-1I, {001}-BiO and {001}-2I facets of bismuth oxyiodide with oxygen vacancy and iodine self-doping through density functional theory computations. The first-principle calculations results indicate that the utilization of visible light region is broadened; thus, the photocatalytic performance is improved via introducing oxygen vacancy or I dopant. In pure state, the {001}-1I facet exhibits the smallest surface energy and the best structural stability, making it easy to expose in the crystal formation process, but its photocatalytic performance is not very well compared to the {001}-BiO facet. When the oxygen vacancy and iodine doping defects are introduced, the photocatalytic performance of {001}-1I facet is improved obviously, while the {001}-BiO facet is changed slightly. Further analysis indicates that the {001}-1I with oxygen vacancy may be the preferred one due to its extremely high structure stability and the best utilization of visible light. So, introducing oxygen vacancy for {001}-1I facet is a potential technology in photocatalytic field that should be considered for degrading organic pollutants and environmental purification.