A first-principles study of hydrogen adsorption on Ni-decorated defective GaN monolayer

Abstract

We systematically study the geometric stability and hydrogen storage capacity of Ni atom decorated GaN monolayer (GaN-ML) with three types defects (VN, VGa and SW defect) using the first-principles calculations based on density functional theory (DFT-D2 method). For Ni-decorated defective GaN-ML, Ni atom can be stably combined on substrates due to higher binding energy, and the Ni atom can accommodate up to three H2 molecules. The H2 molecules adsorbed on Ni-decorated VGa substrate undergo a weak physical interaction. However, the Ni-decorated VN and SW defect substrates show sensitive to H2 molecules, which can satisfy the requirement for hydrogen storage. The molecular dynamics (MD) simulations show that the maximum of eight H2 molecules are stably adsorbed on the Ni atoms at room temperature with the hydrogen storage capacity of 5.36 wt%, and there is no structural deformation of the VN substrate plane. Therefore, these results indicate that the Ni-decorated defective GaN-ML can be potential candidates for better storage of H2 molecules. Our work can supply some guidance to explore promising novel hydrogen storage materials in energy storage field using group III-V nitrides.