Theoretical Study Of The Gas Adsorption Characteristics Of Fullerene C₆₉Si For Gas Sensor

Based on the intersection of gas sensing technology and nanomaterials,this paper studied the gas sensitive characteristics of heterofullerene C69Si by theoretical calculation,in order to expand the selection range of gas sensor materials.As a typical nanomaterial,fullerene have many excellent physical and chemical properties due to their unique geometric and electronic structures,and have important applications in the fields of organic electronics,energy,environment,catalysis,and medicine.Among them,one of the important developments in recent years is the potential application of heterofullerene in the field of gas sensors.Studies have shown that C60-based heterofullerene are a class of high sensitivity,good stability and strong selectivity.Researchers have conducted in-depth research on the sensitive mechanisms of their typical gases.At present,there are few studies on the preparation of C70 with the same high yield.Due to the decrease in the symmetry of C70,the heterofullerene based on C70 is more abundant in electron properties.In view of this,this paper studies the gas adsorption characteristics and sensitive mechanism of heterofullerene C69Si based on the calculation method of density functional theory,which provides technical reference and theoretical basis for the development of new gas sensors in the future.Based on the first-principles calculation method of density functional theory,the geometrical structures and electronic stuctures of heterofullerene C69Si composites adsorbed by gas molecules(CO/NO/HCN)are systematically studied.The research contents include adsorption energy Eads,charge transfer ET,HOMO,LUMO and the band gap Eg,and the distribution of electron cloud and density of states were analyzed to investigate the physicochemical properties of heterofullerene C69Si adsorbed by gas molecules.The main contents and conclusions are as follows:First,a single silicon atom was constructed to replace the different stable structures of the heterofullerene C70.Density functional theory was used to optimize the doping structure of silicon atom replacing one carbon atom of fullerene C70 to form five isomers.The effects of silicon atoms' different substitution positions on the stability of fullerene C70 were studied,and it was found that isomer-1 had the highest reactivity,and isomer-5 had the most stable molecular structure.Secondly,the adsorption properties and molecular orientation of CO,NO and HCN molecules on the surface of heterofullerene C69Si were studied.From the optimized structure,it can be seen that molecules preferentially adsorb near silicon atoms and Si-C bonds of heterofullerene,forming molecular-heterofullerene cluster structure.The adsorption depends on the molecular-heterofullerene interaction and different molecular orientations.Compared with vertical adsorption heterofullerene,CO,NO and HCN molecules prefer parallel adsorption heterofullerene.Moreover,CO-heterofullerene complex only forms C-Si bond,while NO and HCN molecules adsorbed with heterofullerene can form N-Si bond,O-Si bond and C-Si bond.The adsorption energy,HOMO-LUMO band gap and charge number of gas molecules adsorbed with heterofullerene C69Si changed,indicating that the adsorption of gas molecules on the heterofullerene C69Si had an effect on the electronic structure of the corresponding isomers.Finally,the structure,stability and charge distribution of heterofullerene C69Si interacting with gas molecules were analyzed.Studies have shown that toxic gas molecules(CO/NO)are chemisorbed on five isomers with moderate adsorption energy and charge transfer,so the gas sensor based on heterofullerene C69Si has rapid reactivity and short recovery time for gas molecules at room temperature.As the adsorption energy of HCN on C69Si is larger than 1 eV,the recovery time will be longer.Therefore,the heterofullerene C69Si gas sensor is an excellent sensor for detecting CO and NO gas molecules.