Low-dimensional Functional Nanomaterials Based On The Quantum Confinement Effect:Computational Study And Theoretical Design

In the past few years,low-dimensional functional nanomaterials have become the forefront and hotspots in the research of nanomaterials nowadays for their novel properties,as well as a number of potential applications.We can have a better understanding of the low-dimensional functional nanomaterials by the computational study,theoretical design and further analyze of their physical and chemical properties.In addition,by the theoretical study,we can also have a better use of low-dimensional functional nanomaterials for nanoscale devices,new energy,nano-catalysis etc.Although the scientists have made a lot of breakthroughs in the application of low-dimensional functional nanomaterials,however,there remain a series of problems to be solved.For example,the instability of nanowires and the challenge in building effective nanowire-electrode contacts which significantly impedes the practical application of nano devices.The notorious inherent instability of perovskite remains an unavoidable technical barrier for industrial applications of perovskite solar cells.The practical fabrication of stable single-atom catalysts remains a significant challenge and the noble metals are high-cost etc.In this thesis,using first-principles density functional theory(DFT)combine with electronic transport calculations and Scanning Tunneling Microscope(STM)simulations,we systematically studied the above mentioned three systems(borophene nanoribbon,CH3NH3PbBr3 surface defect and single atoms catalyst based on VS2 monolayer).The details of this dissertation are summarized briefly as follows:1.We employed DFT and electronic transport calculations to investigate the stabilities,electronic structures,electrical conductivity of borophene nanoribbons and their interaction with Ag(111)surface.The results indicated that the line-edge borophene nanoribbons are promising for applications as one-dimensional electrical connections in compact nanoscale circuits.2.We have investigated the chemical identities of the CH3NH3PbBr3 surface defects and their effects on the stability of perovskite materials by DFT calculations and STM simulations,which can provide important information for the development of stable perovskite materials.3.We have designed a kind of single atom catalyst,which the transition metal atoms atomically disperse on VS2 monolayer.And we have successfully selected the non-noble single atoms catalyst of Fei/VS2 and Cu1/VS2.We believe this kind of non-noble single atom catalyst can not only improve the atom utilization and catalysis activity of catalyst,but also can greatly reduce the production cost.Based on the theoretical calculation and simulation above,it was successfully indicated that(1)the line-edge borophene nanoribbons are promising for applications as one-dimensional electrical connections in compact nanoscale circuits.(2)The investigation of CH3NH3PbBr3 surface defects may provide important information for understanding the poor stability of perovskite.(3)We have successfully screened the non-noble metal single atom of Fe and Cu on single-layer VS2 surface.Thus,our results can provides reliable theoretical foundations for these challenges in its experimental study.