【摘要】 采用基于密度泛函理论的第一性原理计算方法,研究了AA堆叠型双层石墨烯掺杂Pd原子(Pd/BG)后对气体分子CO和NO的气敏特性和吸附机理。结果表明,Pd原子的掺杂改变了双层石墨烯的电子性质和局部几何结构。Pd原子替代双层石墨烯的一个碳原子后,杂质原子突出层外区域(Po)和突入层间区域(Pi)都可以形成稳定结构,但是突出(Po)构型更有利于气体分子的吸附。对于Po构型,CO和NO吸附在Pd/BG上的最稳定结构是不同的,CO分子与石墨烯表面呈一定夹角,而NO分子近似垂直于石墨烯表面。Pd/BG对NO分子的吸附强于CO分子。气体分子在Po构型上属于化学吸附,而在Pi构型上属于物理吸附。Pd/BG吸附CO和NO气体分子后具有不同的电子性质。Pd/BG体系为半导体性质,在吸附CO气体分子后,转变为金属性,系统无磁性;而在吸附NO气体分子后变为金属性且具有较大磁矩。这种电子性质的变化能够阐明气体分子吸附的敏感程度。研究结果能够为石墨烯基的气体传感器或者探测器提供理论基础和实验指导。更多还原

【Abstract】 The mechanism and sensing properties of gas molecules CO and NO adsorption on the Pd doped AA-stacked bilayer graphene(Pd/BG) were investigated by using first-principles calculations based on density functional theory. After Pd atom replaces one carbon atom in the bilayer graphene, the stable Pd/BG systems can be formed for both the heteroatoms Pd protruding into(Pi) and protruding out(Po) of the interlayer region. The doped layer of bilayer graphene facilitates this region to react with approaching CO and NO molecules because of the higher chemical reactivity of doped Pd atom protrude out of the interlayer region. The doping of Pd atom changes the electronic properties of bilayer graphene. The most stable geometry structure of CO molecule is different from that of the NO molecule adsorption on the Pd/BG system with Po configuration. The CO molecule is at an angle to the graphene surface, while the NO molecules is almost completely perpendicular to the graphene surface. For the most stable structure, the adsorption of NO molecule is more stable than CO molecule on Pd/BG, and the adsorption energy indicate the chemical adsorption for the Po configuration but physical adsorption for the Pi configuration. The CO adsorbed Pd/BG system has dif-ferent electronic structure from that of the NO adsorbed Pd/BG system. After the adsorbing of CO molecule, the Pd/BG system changes from semi-conductive to metallic property, and the Pd/BG-CO system is nonmagnetic, while the Pd/BG-NO system has metallic property with larger magnetic moment. The variational electronic properties can be used to clarify the sensitivity of gas molecule adsorption onto Pd/BG system. Our researching results can provide theoretical basis and experimental guidance for the graphene-based gas sensors or detectors.更多还原