Theoretical Chemistry Study On The Removal Of VOCs On Two-dimensional Materials

In recent decades,with the rapid development of society,people’s high consumption of energy and large number of emissions of pollutants rapidly increases,making environmental pollution increasingly serious.Volatile organic pollutants（VOCs）are one of the important components of air pollutants,which have attracted people’s attention because of their great harm to human health and the environment.Among many methods and technologies for VOCs treatment,adsorption and thermal catalysis are the most commonly used because of their advantages of convenient operation,high efficiency and economic.Suitable adsorption materials and catalytic materials are the key for these two methods.Due to the large specific surface area,two-dimensional nanomaterials have obvious advantages in adsorption and catalysis.Especially,the two-dimensional material borophene has great potential for gas adsorption,and the two-dimensional material C₂N has good performance in the catalytic field after doping metal atoms.In this paper,with the aid of Dmol3 module in Materials Studio software,the DFT are used to（1）calculated the adsorption of a series of VOCs molecules onχ₃ borophene andβ₁₂borophene to confirm the potential of borophenes as the adsorption material,and（2）calculated the degradation process of HCHO on the materials of single Al doping into C₂N to verify the potential of Al₁/C₂N as the catalyst of HCHO,and（3）calculated the process and mechanism of HCHO degradation on difference transition metals doped C₂N to verify the potential of doped C₂N as the HCHO catalyst and search the most suitable doping transition metals.After the above two calculation processes,we obtain the following two results:（1）The adsorption configurations and the adsorption energy for a series of VOCs molecules（including C₂H₆,C₂H₄,HCHO,CH₃OH,HCOOH,CH₃Cl,C₆H₆,and C₇H₈）adsorption onχ₃ borophene andβ₁₂ borophene revels the relatively strong interaction between VOCs and borophenes.Then the analysis of deformation of electronic density and the partial density of states further confirms that C₂H₄ and HCHO are able to chemical adsorption on the boropehen while the others VOCs molecules physical adsorb on the borophene.（2）The adsorption of common atmospheric molecules O₂,CO₂,H₂O,N₂ and pollutant HCHO on Al₁/C₂N reveals that Al₁/C₂N exists in the form of hydrated in the natural environment.However,hydrous Al₁/C₂N can still adsorb HCHO molecules and degrade HCHO into CO₂ and H₂O with the action O₂ in the environment and the largest energy barrier for the whole process is 0.87 e V.Therefore,it is confirmed that Al₁/C₂N can be used as a catalyst for the degradation of HCHO at room temperature.（3）A series of transition metal（including Cr,Mn,Fe,Co and Ni）dope into C₂N with the form of single atom and dimer atoms to form TM₁/C₂N and TM₂/C₂N.Then,the process of HCHO degradation on these TM₁/C₂N and TM₂/C₂N are calculated and the analysis of each elementary reaction in the degradation reaction reveals that the degradation of HCHO is more likely to occur on Co₁/C₂N,Co₂/C₂N和Ni₂/C₂N with the maximum energy barriers of 0.83e V,0.62 e V和0.70 e V,respectively.Therefore,Co₁/C₂N,Co₂/C₂N and Ni₂/C₂N are suitable for HCHO degradation at room temperature and atmospheric pressure,and CO₂/C₂N is the best.