Visible light photocatalysis of single-walled (Zn4/6Cu2/6O)3/(Zn5/6Cu1/6O)3 superlattice nanotube for redox reaction of water calculated by generalized gradient approximations with the Hubbard U model

Abstract

To use ZnO for visible light water photoelectrolysis, the bandgap Eg of ZnO should be dropped into the visible light region. This is realized by establishing a novel single-walled (Zn4/6Cu2/6O)3/(Zn5/6Cu1/6O)3 superlattice nanotube of (6,0) type, whose Eg is determined using the density functional theory of generalized gradient approximations with the Hubbard U model (GGA + U). The results show that the Eg value of the superlattice is 2.16 eV. The absorption ability of the incident solar spectrum reaches 42% in comparison with 5% of ZnO. The physical mechanism of this band structure variation is the existence of the concentration gradient of Cu at the interface within the superlattice. The corresponding location of the superlattice of the bandgap also satisfies the redox reaction of water. Thus, the superlattice can be an exciting candidate for water photoelectrolysis materials using visible light.