采用基于密度泛函理论的第一性原理方法研究了单个CO和O2气体分子在金属原子修饰石墨烯表面的吸附和反应过程.结果表明:空位缺陷结构的石墨烯能够提高金属原子的稳定性,金属原子掺杂的石墨烯体系能够调控气体分子的吸附特性.通入混合的C...采用基于密度泛函理论的第一性原理方法研究了单个CO和O2气体分子在金属原子修饰石墨烯表面的吸附和反应过程.结果表明:空位缺陷结构的石墨烯能够提高金属原子的稳定性,金属原子掺杂的石墨烯体系能够调控气体分子的吸附特性.通入混合的CO和O2作为反应气体,石墨烯表面容易被吸附性更强的O2分子占据,进而防止催化剂的CO中毒.此外,对比分析两种催化机理(Langmuir-Hinshelwood和Eley-Rideal)对CO氧化反应的影响.与其它金属原子相比,Al原子掺杂的石墨烯体系具有极低的反应势垒(<0.4 e V),更有助于CO氧化反应的迅速进行.展开更多
The geometries and electronic properties of SnSe/metal contact have been investigated using first-principles calcula- tion. It is found that the geometries of monolayer SnSe were affected slightly when SnSe adsorbs on...The geometries and electronic properties of SnSe/metal contact have been investigated using first-principles calcula- tion. It is found that the geometries of monolayer SnSe were affected slightly when SnSe adsorbs on M （M = Ag,Au,Ta） substrate. Compared with the corresponding free-standing monolayer SnSe, the adsorbed SnSe undergoes a semiconductor- to-metal transition. The potential difference AV indicates that SnSefra contact is the best candidate for the Schottky contact of the three SnSe/M contacts. Two types of current-in-plane （CIP） structure, where a freestanding monolayer SnSe is con- nected to SnSe/M, are identified as the n-type CIP structure in SnSe/Ag contact and p-type CIP structure in SnSe/Au and SnSe/Ta contact. The results can stimulate further investigation for the multifunctional SnSe/metal contact.展开更多
The structures of Pt clusters on nitrogen-, boron-,silicon- doped graphenes are theoretically studied using densityfunctional theory. These dopants （nitrogen, boron and silicon） each do not induce a local curvature ...The structures of Pt clusters on nitrogen-, boron-,silicon- doped graphenes are theoretically studied using densityfunctional theory. These dopants （nitrogen, boron and silicon） each do not induce a local curvature in the graphene and the doped graphenes all retain their planar form. The formation energy of the silicon-graphene system is lower than those of the nitrogen-, boron-doped graphenes, indicating that the silicon atom is easier to incorporate into the graphene. All the substitutional impurities enhance the interaction between the Pt atom and the graphene. The adsorption energy of a Pt adsorbed on the silicon-doped graphene is much higher than those on the nitrogen-and boron-doped graphenes. The doped silicon atom can provide more charges to enhance the Pt-graphene interaction and the formation of Pt clusters each with a large size. The stable structures of Pt clusters on the doped-graphenes are dimeric, triangle and tetrahedron with the increase of the Pt coverage. Of all the studied structures, the tetrahedron is the most stable cluster which has the least influence on the olanar surface of doned-graohene.展开更多
文摘采用基于密度泛函理论的第一性原理方法研究了单个CO和O2气体分子在金属原子修饰石墨烯表面的吸附和反应过程.结果表明:空位缺陷结构的石墨烯能够提高金属原子的稳定性,金属原子掺杂的石墨烯体系能够调控气体分子的吸附特性.通入混合的CO和O2作为反应气体,石墨烯表面容易被吸附性更强的O2分子占据,进而防止催化剂的CO中毒.此外,对比分析两种催化机理(Langmuir-Hinshelwood和Eley-Rideal)对CO氧化反应的影响.与其它金属原子相比,Al原子掺杂的石墨烯体系具有极低的反应势垒(<0.4 e V),更有助于CO氧化反应的迅速进行.
基金supported by the National Natural Science Foundation of China(Grant Nos.U1304518 and U1404109)
文摘The geometries and electronic properties of SnSe/metal contact have been investigated using first-principles calcula- tion. It is found that the geometries of monolayer SnSe were affected slightly when SnSe adsorbs on M （M = Ag,Au,Ta） substrate. Compared with the corresponding free-standing monolayer SnSe, the adsorbed SnSe undergoes a semiconductor- to-metal transition. The potential difference AV indicates that SnSefra contact is the best candidate for the Schottky contact of the three SnSe/M contacts. Two types of current-in-plane （CIP） structure, where a freestanding monolayer SnSe is con- nected to SnSe/M, are identified as the n-type CIP structure in SnSe/Ag contact and p-type CIP structure in SnSe/Au and SnSe/Ta contact. The results can stimulate further investigation for the multifunctional SnSe/metal contact.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60476047)the Henan Science and Technology Innovation Talent Support Program,China (Grant No. 2008HASTIT030)the Innovation Scientists and Technicians Troop Construction Projects of Henan Province,China (Grant No. 104200510014)
文摘The structures of Pt clusters on nitrogen-, boron-,silicon- doped graphenes are theoretically studied using densityfunctional theory. These dopants （nitrogen, boron and silicon） each do not induce a local curvature in the graphene and the doped graphenes all retain their planar form. The formation energy of the silicon-graphene system is lower than those of the nitrogen-, boron-doped graphenes, indicating that the silicon atom is easier to incorporate into the graphene. All the substitutional impurities enhance the interaction between the Pt atom and the graphene. The adsorption energy of a Pt adsorbed on the silicon-doped graphene is much higher than those on the nitrogen-and boron-doped graphenes. The doped silicon atom can provide more charges to enhance the Pt-graphene interaction and the formation of Pt clusters each with a large size. The stable structures of Pt clusters on the doped-graphenes are dimeric, triangle and tetrahedron with the increase of the Pt coverage. Of all the studied structures, the tetrahedron is the most stable cluster which has the least influence on the olanar surface of doned-graohene.
