First-principles Studies Of Structural, Electronic And Hydrogen Storage Properties Of Layered C_xN Compounds

In this disseration, experimental and computational works for the layered C_xN materials in the recent literatures were reviewed. The structural and electronic properties of graphite-like C_xN materials were studied by a first-principles method. And the hydrogen storage properties of the layered C_xN materials were also explored and predicted.Possible layered C₃N, C₅N, C₇N configurations were constructed based on hexagonal BN and graphite structure. The atomic arrangement within the monolayer and stacking sequence along c axis for the constructed C_xN models were studied using ab initio pseudopotential density functional method within the local density approximation as implemented in CASTEP code. The band structure and density of state (DOS) were also computed to predicting the electronic structure. The calculated results show that the C₃N-IV, C₅N-I and C₇N-I configurations are the most stable in the three kind of C₃N, C₅N and C₇N compounds respectively. The calculated results of formation energy indicate that all of the C₃N, C₅N and C₇N compounds are stable.The adorption of hydrogen atoms on the surface of C₃N monolayer was also studied by CASTEP program. When only one hydrogen atom was adsorbed on the surface of C₃N monolayer, this hydrogen atom preferred to adsorb on the top of C-N bonds. And the adsorption energy for hydrogen atom on the surface of C₃N monolayer. This results show that the graphene-like C₃N compound may be a material with better hydrogen storage performance.The calculated research on the full hydrogenation of three layer C₃N compounds indicated that the full hydrogenation is not feasible, but a partial hydrogenation is feasible.