First-principles study on the strain-mediated g-CN/blue phosphorene heterostructures for promising photocatalytic performance.

Well-designed two-dimensional heterogeneous photocatalysts have attracted significant attention due to the enhancement in visible-light absorption and effective charge separation. In this paper, the electronic and optical properties of g-CN/BlueP (blue phosphorene) heterojunction under varying strains were investigated systematically by first-principles calculations. The results showed that the type transformation of g-CN/BlueP heterojunction can be achieved by suitable biaxial strain. The CBM was found to be composed of g-CNas electron acceptor, while the VBM was contributed by BlueP as electron donor which solved the problem of high electron-hole recombination of type-I heterostructures. The band gap and band edge alignment under -6% to -8% compressive biaxial strain could satisfy the REDOX (reduction-oxidation) potential of photolysis water. A wide optical response range and good absorbance were also observed for the heterostructure under strain, which improved the solar utilization rate compared with individual g-CNand BlueP.