Theoretical Study On The CO Oxidation And Hydrogen Storage Properties Of Non-noble Metal Decorated Graphdiyne

Since its successful preparation in 2010,the two-dimensional graphdiyne has become the research hotspot due to its rich chemical bonds,large conjugated structure,high specific surface area,excellent semiconducting properties and unique physicochemical properties,which is expected to be widely used in the fields of environment and energy.The current studies show that the strain will not only affect the geometrical structure of the materials,but also change the electronic structure.Therefore,it is of great significance to study the strain effect of graphdiyne.Graphdiyne has large specific surface area and porous structure,which is an ideal support for single metal atom.The embedding of single metal atom on graphdiyne can maximize the utilization of single metal atom,which will have potential applications in CO oxidation and hydrogen storage.In this dissertation,the external strain and non-noble metal decoration on the electronic structure,CO oxidation and hydrogen storage properties of graphdiyne have been investigated using density functional theory.The detailed results and main conclusions are summarized as follows.(1)The effects of external tensile and compressive strains on the geometrical structure and electronic structure of graphdiyne are studied.The results show that graphdiyne can withstand the strain in the range from-13% compressive strain to 15%tensile strain.In this range of strain,the C-C bond length of graphdiyne changes approximately linearly with strain.With the increase of the external strain,the strain energy presents a monotonous increasing trend.The band gap of graphdiyne decreases slowly with the increase of the compressive strain and increases slowly with the increase of the tensile strain.(2)The CO oxidation of graphdiyne embedded with Ni and Cu atoms have been detailedly investigated.The results of the adsorption energy and the diffusion barrier show that Ni and Cu atoms can be stably adsorbed on the surface of graphdiyne.Furthermore,several CO oxidation reaction paths are established,and the optimal reaction path and the reaction mechanism of CO oxidation are determined through transition state search.The results show that the CO oxidation on the surface of graphdiyne embedded with Ni and Cu atoms is completed through the Langmuir-Hinshelwood mechanism and the subsequent Eley-Rideal mechanism.The reaction barrier of the rate-limiting step for the CO oxidation on Ni embedded graphdiyne is 0.81 e V,and the reaction barrier of the rate-limiting step for the CO oxidation on Cu embedded graphdiyne is 0.75 e V.The above studies show that low-cost and high active Ni and Cu embedded graphdiyne are excellent catalysts for CO oxidation.(3)The hydrogen storage performance of graphdiyne embedded with Ca and Li atoms have been detailedly studied.The stable adsorption positions of Ca and Li atoms on the surface of graphdiyne are determined by the geometrical optimization.In the investigation of the hydrogen storage performance,10 and 20 hydrogen molecules can be stably adsorbed on the surface of the single and double Ca atoms embedded graphdiyne,respectively,and the corresponding hydrogen storage gravimetric density are 7.31 wt% and 12.00 wt%,respectively.At the same time,10 and 16 hydrogen molecules can be stably adsorbed on the surface of the single and double Li atoms embedded graphdiyne,respectively,and the corresponding hydrogen storage gravimetric density are 8.30 wt% and 12.32 wt%,respectively.The above studies show that the Ca and Li embedded graphdiyne exhibit excellent hydrogen storage performance.