First‐principles study on the methane adsorption properties by Ti‐modified graphyne. Issue 24 (24th August 2021)

• Record Type: Journal Article
• Authors: Xu, Wenhui; Chen, Yuhong; Zhao, Yingjie; Zhang, Meiling; Tian, Ranran; Zhang, Cairong
• Is Part Of: International journal of quantum chemistry. Volume 121:Issue 24(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-08-24
• Subjects: a first‐principles -- adsorption properties -- graphyne -- methane; Quantum chemistry -- Periodicals; 541.28
• DOI: 10.1002/qua.26811
• Languages: English
• ISSNs: 0020-7608

Abstract

Abstract: Graphyne (GY) is an allotrope composed of sp and sp 2 hybridized carbon atoms. In this paper, the adsorption performance of Ti‐modified GY (Ti‐GY) system on the adsorption of CH4 molecules is studied based on first principles. The study found that the most stable adsorption site for Ti atoms is the six‐membered carbon ring pore site. There is a strong ionic interaction between the two, and the Ti‐GY system structure remains stable during the adsorption of CH4 molecules. A single Ti‐modified GY can adsorb 7 CH4 molecules on one side, and the adsorption structure is stratified, with average adsorption energy of −0.298 eV, and an adsorption capacity of 0.369 g g −1 ; two Ti‐modified GY adsorbs 14 CH4 molecules on double‐sided, the average adsorption energy is about −0.300 eV, and the adsorption capacity reaches 0.484 g g −1 . The first layer of CH4 molecules is adsorbed, which is mainly affected by the Ti atoms. There is a strong Coulomb interaction between it and Ti. With the increase of CH4 molecules, the adsorption energy decreases; While the second layer of CH4 molecules is due to the distance Ti atoms are far away, At this time, the interaction between the CH4 molecules and the substrate is mainly the electrostatic interaction between the positively charged CH4 molecules and the negatively charged GY and the van der Waals interaction between the CH4 molecules. The adsorption performance of CH4 molecules is closely related to the pore size of the two‐dimensional adsorbent. When the pore size is small, the interaction between molecules is enhanced and the average adsorption energy is larger. On the contrary, the larger the pore size, the higher the adsorption capacity. Abstract : DFT predicts that Ti atom can significantly improve the adsorption performance of CH4 on graphyne (GY). GY system adsorbs is 14 CH4 molecules, the storage capacity reaches 0.484 g g −1, which is close to the US DOE energy storage target. It was also found that the adsorption performance for CH4 molecules is closely related to the pore size of the adsorbent.