Interface Effect Modification On The Device Performance Of Two-Dimensional Materials

Interface is very common in two-dimensional(2D)materials based devices and profoundly influences material properties and device performance.In this work,using first-principles calculations,we systematically investigated the electronic,magnetic and catalytic properties of some rising 2D materials(including black phosphorous,CrI3,MgO ultrathin film and g-C3N4),and explored the effects of interlayer rotation,substrate,and surface decoration on their applications of electronics,spintronics and energy conversion.These results not only deepen the understanding of interface properties of 2D materials,but also provide valuable guidance for rationally designing novel 2D materials-based devices and precisely regulating their performance.2D twisted bilayer materials have displayed rich novel physical phenomena,depending on the interlayer interaction mediated by rotation angle.By first-principles calculations,we systematically investigated the geometrical and electronic properties of twisted bilayer black phosphorene(BP),and found that the interlayer cohesive energy relies on the rotation angle with a periodicity of about 36°,which can be understood by the angle-dependent coupling strength of the lone-pair electrons from adjacent P atoms in the upper and lower layers.Interestingly,the electronic and transport anisotropy of the twisted bilayer BP can be continuously tuned by changing the twisted angle from 0° to 90°.In addition,an electronic polarization along the vertical direction exists in the twisted bilayer BP with weak interlayer interaction,which results in band structure and charge density distribution distinct from those of the bilayer systems with strong interlayer coupling.The substrate interaction greatly influences the magnetic properties of 2D materials.We showed that the proximity effect from bulk semiconducting substrates induces electronic doping and significantly increases the ferromagnetic(FM)nearest-neighbor exchange for bilayer CrI3,leading to the transition from antiferromagnetic(AFM)to FM interlayer spin configuration as well as enhanced intralayer FM coupling.Bulk and 2D semiconductors providing different interaction strengths from strong covalent bonding to weak van der Waals(vdW)interaction with Crl3 are compared to thoroughly address the substrate effect on magnetic behavior and Curie temperature of bilayer CrI3.In addition,the interfacial charge transfer between 2D materials and substrates has a key effect on the surface properties of 2D materials.We studied the structures and catalytic behavior of 2D magnesium oxide(MgO)overlayers on transition metal substrates for CO2 reduction.The electronic coupling between metal substrates and MgO overlayers can not only stabilize the structures of monolayer or multilayer MgO,but also induce extra surface electronic states,which rise the Fermi level of MgO overlayers to approach the anti-bonding orbital of CO2 molecule.As a result,the supported MgO sheet is capable of activation and reduction of CO2,with the product selectivity controllable by number of layers and exposed surface of MgO sheet,as well as the type and facets of metal substrates.We further investigated the key parameters controlling the catalytic activity and selectivity,and determined the descriptors including the p-band center of MgO sheets and the work function of 2D MgO/metal heterostructures.These findings provide universal guidance for rationally designing low-price,environmentally friendly,and efficient catalysts for energy conversion.Surface modification of 2D materials by functional groups or small clusters to form heterogeneous structures can also regulate their surface properties.We showed that loading subnanometer p-block metal oxide clusters on the periodic holes of 2D porous carbon-based semiconductors can trigger peculiar synergistic effect and offer an effective route for manipulating the photocatalytic behavior.As a prototype system,g-C3N4 monolayer decorated by tubular MgO clusters for overall water splitting is explored by time-dependent ab initio nonadiabatic molecular dynamic simulations.The basic rules for optimally steering the relaxation pathway and lifetime of excited carriers,enhancing the optical absorbance,and creating bifunctional reaction centers by controlling the concentration and size of oxide clusters are thoroughly unveiled.These results provide a novel strategy to modify 2D porous carbon materials for practical solar energy conversion and shines light on utilizing subnanometer pblock oxide clusters for precisely dictating the performance of hybrid photocatalysts.The above research results help to understand the effects of interfacial effects on the electronic,magnetic and photoelectric properties of 2D materials at the atomic scale,and lay an important theoretical foundation for accurately designing of high-performance 2D devices.