First-principles Study Of The Adsorption Properties Of Formaldehyde Molecules On The Surface Of Borophene

With the continuous improvement of the quality of human life,people pay more and more attention to the indoor environment.Formaldehyde?HCHO?is the most well-known indoor air pollution gas.Two-dimensional nanomaterials such as graphene have excellent characteristics such as large specific surface area,high carrier rate,low adsorption heat,low activation energy,and good cycleability.It brings new opportunities for the adsorption of HCHO molecules.In recent years,a variety of graphene-like two-dimensional materials have been experimentally prepared.As a graphene-like material,boronene has successfully prepared three structures of?₆-borophene,?₁₂-borophene and?₃-borophene with a single atom thickness.The structures of?₁₂-borophene and?₃-borophene are relatively stable.Borophene has a smaller mass and more active properties than graphene,so it has great potential as a gas molecule gas detection and adsorbent.In this paper,first-principles density functional theory calculations were used to first study the adsorption properties of HCHO molecules in the?₃-borophene and Li-?₃-borophene systems.Li atom modification can improve the adsorption performance of?₃-borophene to HCHO.The results show that HCHO molecules cannot be stably adsorbed on the surface of?₃-borophene.When HCHO molecules are adsorbed on the surface of Li-?₃-borophene,the adsorption energy is significantly increased,and the adsorption energy of the most stable structure is-0.665 eV.By calculating the adsorption amount of HCHO molecules by Li-?₃-borophene,it was found that the Li-?₃-borophene system can adsorb 11 HCHO molecules on one side,the adsorption amount reached 45.47 wt.%,the average adsorption energy is-0.293 eV,and stratified from the 6th HCHO molecules;The 2Li-?₃-borophene system can adsorb 22 HCHO molecules on both sides,with an adsorption amount of 62.11wt.%,and an average adsorption energy of-0.283 eV.Analysis of the geometric structure and electronic properties of the system revealed that after Li-?₃-borophene adsorbed HCHO molecule,the conductivity of the system was enhanced and the structure was stable.It is a potential gas-sensitive material for detecting HCHO molecules.As the number of HCHO molecules continues to increase,the interaction between HCHO molecules and Li atom weakens,and the adsorption energy decreases.The distance between Li atom and the?₃-borophene substrate increases,the interaction is weakened,and the stability of the system is reduced.In the case of rapid release of gas molecules,Li atom are likely to fall off,which is not conducive to the recycling of materials.Using first-principles density functional theory calculations,this paper also studies the adsorption properties of HCHO molecules in?₁₂-borophene and Li-?₁₂-borophene systems.The results showed that?₁₂-borophene had weak adsorption effect on HCHO molecule,and the adsorption energy of the most stable structure was only-0.313 eV.Li atom modification can improve the adsorption performance of?₁₂-borophene to HCHO.The most stable structure of Li-?₁₂-borophene for HCHO has an adsorption energy of-0.983 eV,which is much higher than the?₁₂-borophene and Li-?₃-borophene for HCHO.By studying the adsorption amount of HCHO by Li-?₁₂-borophene,it was found that 5 HCHO molecules can be adsorbed on one side of the system,and the 4th HCHO molecule is adsorbed in the second layer;It can adsorb 10 HCHO molecules on both sides,with an adsorption capacity of 56.61wt.%,and an average adsorption energy of-0.673 eV.The mild adsorption energy is conducive to desorption of adsorbed molecules and the reuse of materials.By analyzing the geometric structure and electronic properties of the system,it was found that Li-?₁₂-borophene has a higher adsorption energy for HCHO molecules,and the conductivity of the system after adsorption is enhanced.As the number of adsorbed HCHO molecules increases,the interaction between Li atom and HCHO molecules decreases,and the adsorption energy decreases.The distance between Li atom and B atom changes little,and the stability of the system is high.It is an ideal choice for HCHO molecular detection and adsorption materials.