金属Sc修饰Ti_(2)CO_(2)吸附气体分子的第一性原理研究

First-principles study on adsorption of gas molecules by metal Sc modified Ti_(2)CO_(2)

基于第一性原理计算研究了Ti_(2)CO_(2)和金属Sc修饰的Ti_(2)CO_(2)的几何结构和电子性质,分析了不同有害气体(CO,NH_(3),NO,SO_(2),CH_(4),H_(2)S)在这两种材料表面的吸附过程,讨论了金属修饰对Ti_(2)CO_(2)二维过渡金属碳化物(MXene)电子性能和气体吸附性能的影响.计算结果表明,Sc原子位于空心位C原子上方的结构具有较大的结合能,但小于固体Sc的内聚能实验值(3.90 e V),Sc原子可以有效避免成簇.表面Sc金属为气体吸附提供了活性位点.通过分析不同气体的最佳吸附点位、吸附能等参数,分析金属Sc修饰的Ti_(2)CO_(2)对这些气体的吸附效果.其中对SO_(2)的吸附效果更好,吸附能从–0.314 eV提升到–2.043 eV,其他气体的吸附效果均有改善.通过电荷转移、态密度和功函数等参数解释了其吸附能增加的原因.由于在表面引入了新的原子,增大了材料的载流子密度和载流子迁移率,从而提高了材料表面的电荷转移,为金属Sc修饰的Ti_(2)CO_(2)材料的气敏性能提供理论参考.

MXene materials have received increasing attention due to their unique properties and potential applications.Ti_(2)CO_(2),as a typical MXene material that has been prepared,has been widely studied.The adsorption characteristics of two-dimensional materials for gas molecules can be significantly improved through transition metal modification.However,there are few studies on the use of transition metals to modify Ti_(2)CO_(2).In this work,the adsorption processes of different harmful gases(CO,NH_(3),NO,SO_(2),CH_(4),H_(2)S)on the surfaces of these two materials,i.e.Ti_(2)CO_(2)and metal Sc modified Ti_(2)CO_(2),are studied and analyzed based on firstprinciples density functional theory and generalized gradient method.The geometric optimization calculation of the metal-modified adsorption harmful gas structure is carried out,and the kinetic energy cutoff energy of the plane wave basis set is taken as 450 eV.The calculation results show that the structure in which Sc atoms are located above the C atoms in the hollow position has a large binding energy,but it is smaller than the experimental value of the cohesive energy of solid Sc(3.90 eV).Sc atoms can effectively avoid clustering.Surface Sc metal provides active sites for gas adsorption.By analyzing the optimal adsorption points,adsorption energy and other parameters of different gases,the adsorption effects of metal Sc-modified Ti_(2)CO_(2)on these gases are analyzed.Among them,the adsorption effect of SO2 is better,the adsorption energy is increased from–0.314 eV to–2.043 eV,and the adsorption effects of other gases are improved.Due to the introduction of new atoms on the surface of Ti_(2)CO_(2),the carrier density and carrier mobility of the material are increased,thereby improving the charge transfer on the surface of the material,which is beneficial to its sensitivity to gas molecules.The results of density of states and work function further verify that the carrier density and carrier mobility of Sc-Ti_(2)CO_(2)are increased,which is beneficial to gas adsorption.It is expected that the metal Sc-modified Ti_(2)CO_(2)becomes an excellent gas-sensing material for the detection of CO,NH_(3),NO,SO_(2),CH_(4)and H_(2)S,and the present work can provide a reference for theoretically studying the gas-sensing performance of metal Sc-modified Ti_(2)CO_(2)materials.