Theoretical study on photocatalytic performance of ZnO/CN heterostructure towards high efficiency water splitting.

The construction of van der Waals heterostructures offers effective boosting of the photocatalytic performance of two-dimensional materials. In this study, which uses the first-principles method, the electronic and absorptive properties of an emerging ZnO/CN heterostructure are systematically explored to determine the structure's photocatalytic potential. The results demonstrate that ZnO and CN form a type-II band alignment heterostructure with a reduced band gap, and hence superior absorption in the visible region. Furthermore, the band edge positions of a ZnO/CN heterostructure meet the requirements for spontaneous water splitting. The ZnO/CN heterostructure is known to possess considerably improved carrier mobility, which is advantageous in the separation and migration of carriers. The Gibbs free energy calculation confirms the high catalytic activity of the ZnO/CN heterostructure for water-splitting reactions. All the aforementioned properties, including band gap, band edge positions, and optical absorption, can be directly tuned using biaxial lateral strain. A suitable band gap, decent band edge positions, high catalytic activity, and superior carrier mobility thus identify a ZnO/CN heterostructure as a prominent potential photocatalyst for water splitting.