First-principles study of CO gas adsorption on pristine and Fe-doped H<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="d1e1723" altimg="si98.svg"><mml:msub><mml:mrow /><mml:mrow><mml:mn>4</mml:mn><mml:mo>,</mml:mo><mml:mn>4</mml:mn><mml:mo>,</mml:mo><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:math>-graphyne

Due to the advantages of high surface volume ratio, stable structure and easy modification, two-dimensional carbon materials have received extensive attention in recent years. In order to find suitable materials for detecting or storing toxic carbon monoxide (CO) gas, first-principles calculations are used to systematically investigate the adsorption performance of pristine H 4 , 4 , 4 -graphyne (H 4 , 4 , 4 -G) and Fe-doped H 4 , 4 , 4 -graphyne (Fe-H 4 , 4 , 4 -G) for CO. The calculation results show that only weak physical adsorption occurs between CO and H 4 , 4 , 4 -G. On the contrary, in the Fe-H 4 , 4 , 4 -G system, the substrate interacts strongly with CO and chemical adsorption occurs. Fe-H 4 , 4 , 4 -G has excellent adsorption performance for CO and the charge transfer is more obvious. Its adsorption energy and charge transfer are -1.601 eV and -0.167 e, respectively. Therefore, Fe-H 4 , 4 , 4 -G can be used as a candidate material for storage or detection of CO. In addition, the applied electric field can effectively control the gas sensitivity of Fe-H 4 , 4 , 4 -G, and further enhance the adsorption performance of CO on the substrate. It is expected that CO can be captured or released by Fe-H 4 , 4 , 4 -G. The results of this research will help advance the study of the adsorption characteristics of H 4 , 4 , 4 -G, and the Fe-doped H 4 , 4 , 4 -G will provide a new idea for the application of gas sensors. • Adsorption behaviors of CO gas on pristine H 4 , 4 , 4 -graphyne (H 4 , 4 , 4 -G) and Fe-doped H 4 , 4 , 4 -graphyne (Fe-H 4 , 4 , 4 -G) were studied by DFT. • Week physisorption occurs between CO gas and the surface of H 4 , 4 , 4 -G. • The doping of a Fe atom in the Fe-H 4 , 4 , 4 -G system makes it interact strongly with CO gas and chemisorption occurs. • The adsorption properties of Fe-H 4 , 4 , 4 -G can be effectively controlled by applied electric field, so as to achieve the capture and release of CO gas.