Study On The Stability And Electrocatalytic Properties Of Hexagonal Borophene Based On Heterojunction Engineering

In recent years,two-dimensional（2D）boron materials have been widely studied due to their unique structural diversity and excellent mechanical,electrical and thermal properties.Among the various allotropes,δ₃borophene,with a special hexagonal honeycomb lattice,exhibits poor performance in thermodynamics and kinetic stability due to the lack of electrons in its structure,which limits further research on its properties and applications.Usually,the stability ofδ₃borophene can be improved by metal decoration,chemical functionalization,or the design of heterostructure.Notably,the combination of borophene and different 2D materials to construct a heterostructure can not only alleviate the electron deficiency of boron element with the electron transfer in the interface and improve the thermodynamic stability of the structure,but also make some new properties of the system owing to the interface synergistic effect,which is conducive to further promoting the functionalization of borophene.The main work and innovation points of this thesis are as follows:Firstly,considering the electron deficiency and low stability ofδ₃borophene,2D materials with good stability were selected from the C2DB database as substrates to build heterostructures by high-throughput screening,and eight 2Dδ₃borophene based heterostructures with excellent performance were finally screened through thermodynamic stability tests.Then,in view of the good stability performance of the eight heterostructures,the mechanism of stability enhancement was analyzed from the perspectives of binding energy,charge redistribution,interfacial neighbor atomic bonding tendency and band structure.The results show that the stability of the eight heterostructures mainly comes from two aspects:electron transfers between the two components and strong covalent bonding between neighboring atoms at the interface.Furthermore,the adsorption and diffusion behavior of boron atoms on the surface of Ti₃N₂substrate showed that the adsorption and diffusion of boron atoms were mainly carried out at the hollow sites on the substrate surface,and the boron atoms reaching the substrate surface were more inclined to aggregate with the existing boron atoms to form a stable six-membered boron ring.The nearby boron atoms could diffuse to the adjacent sites of the six-membered boron ring to form a more stable adsorption after overcoming the 0.26 e V barrier.Finally,the performance of hc-B/Ti₃N₂as a HER catalyst was analyzed.The adsorption of single H atom at the optimal site on the surface of hc-B/Ti₃N₂heterojunction showed a free energy of-0.33 e V,and after increasing H coverage,the corresponding Gibbs free energyΔG_Hreached-0.30 e V,indicating that hc-B/Ti₃N₂had good HER catalytic activity.In conclusion,eightδ₃borophene based heterostructures were obtained by high-throughput screening.The research and analysis of their thermodynamic stability,electronic properties and catalytic performance showed that the construction of 2D heterostructure could effectively improve the poor stability ofδ₃borophene.In addition,the hc-B/Ti₃N₂heterostructure exhibits promising potential as HER reaction catalyst.