Catalytic potential of highly defective (211) surfaces of zinc blende ZnO.

Zinc blende (ZB) ZnO has gained increasing research interest due to its favorable properties and its stabilization on the nanoscale. While surface properties are important on the nanoscale, the studies on ZB ZnO surface properties are rare. Here we have performed first principles calculations of the energies and structures of ZB and wurtzite (WZ) ZnO surfaces. Our results indicate that, among the four surfaces parallel to the polar axes, such as (101̄0) and (112̄0) of the WZ phase and (110) and (211) of the ZB phase, the polar (211) surface has substantially lower surface vacancy formation energies than the others, which makes ZB ZnO promising for catalytic applications. Our results also imply that the stabilization of ZB ZnO on the nanoscale is due to some mechanisms other than surface energies.