First Principles Study Of Structural,Electronic,Optical And Electrochemical Properties Of BlackP/BlueP Heterostructure And Ultra-Wide Bandgap NaYO₂

Electrochemical energy storage is an effective strategy to achieve the strong demand of green en-ergy.Rechargeable lithium-ion batteries(LIBs)are one of the famous electrochemical maneuvers that have been used in various applications.LIBs current research challenge is to increase the energy density to meet the demands of emerging markets,especially in electric vehicles,and port-able smart electronics.The available commercial anode material cannot satisfy the requirement for the long drive.Considerable efforts are being put into either explore new carbon morphologies or looking for new nanomaterials with high potential lithium-ion storage capacities.Black Phos-phorene(BLK-P),Blue Phosphorene(BLE-P),and their composite heterostructure have attracted enormous attention.This master’s research focused on two topics:(1)developing a BLK-P/BLEP free-standing surface heterostructure used as anodes for LIBs,for potential applications as anode for LIBs;(2)Structural,electronic and optical investigation of ultra-wide bandgap NaYO2 for possible solar blind detector and harsh environment application.Based on first-principles approaches,we propose that the BLK-P/BLE-P vdW heterostructure can be a capable anode material for power-driving LIBs,which exhibits a large theoretical capacity,together with relatively strong binding strength compared to BLK-P and BLE-P monolayers.The theoretical specific capacity is found to be as high as 552.8 mAhg-1,which can be attributed to the much higher storage capacity of Li adatoms in BLK-P/BLE-P vdW heterostructure.Furthermore,the electronic structure calculations reveal that a large amount of charge transfer assists in semi-conductor to metallic transition upon lithiation,ensuring good electrical conductivity.We also systematically studied the electronic and optical properties of NaYO2 in two different phases.The underestimated bandgap calculated from the standard density-functional theory(DFT)in the generalized gradient approximation(GGA)cannot predict the material properties accurately’close to the experiment.Herein,going beyond the DFT,we employ the more advance and accurate screened-hybrid functional DFT approach to evaluate the electronic and optical properties of NaYO2.Our calculated bandgap 5.4 eV with HSE06 functional matches the experimental value and depicts that the previously theoretical value was underestimated.Further,we calculate the optical response with the correct HSE06 functional.