title: Ultrahigh Thermal Rectification in Pillared Graphene Structure with Carbon Nanotube-Graphene Intramolecular Junctions.
abstract: In this letter, graded pillared graphene structures with carbon nanotube-graphene intramolecular junctions are demonstrated to exhibit ultrahigh thermal rectification. The designed graded two-stage pillared graphene structures are shown to have rectification values of 790.8 and 1173.0% at average temperatures 300 and 200 K, respectively. The ultrahigh thermal rectification is found to be a result of the obvious phonon spectra mismatch before and after reversing the applied thermal bias. This outcome is attributed to both the device shape asymmetry and the size asymmetric boundary thermal contacts. We also find that the significant and stable standing waves that exist in graded two-stage pillared graphene structures play an important role in this kind of thermal rectifier, and are responsible for the ultrahigh thermal rectification of the two-stage ones as well. Our work demonstrates that pillared graphene structure with SWCNT-graphene intramolecular junctions is an excellent and promising phononic device.
authors.affiliation: Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics, Tsinghua University , Beijing 100084, China.|Department of Power Engineering, North China Electric Power University , Baoding 071003, China.
authors.forename: Xueming
authors.identifier: 0000-0001-7309-7817
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Power Engineering, North China Electric Power University , Baoding 071003, China.
authors.forename: Dapeng
authors.initials: D
authors.lastname: Yu
authors.affiliation: Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics, Tsinghua University , Beijing 100084, China.
authors.forename: Bingyang
authors.initials: B
authors.lastname: Cao
authors.affiliation: Department of Mechanical Engineering and Materials Science, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States.
authors.forename: Albert C
authors.initials: AC
authors.lastname: To
mesh_terms: D006108:Graphite / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D013696:Temperature; D013814:Thermal Conductivity
chemical_list: D037742:Nanotubes, Carbon; D006108:Graphite
keywords: carbon nanotube-graphene intramolecular junctions; molecular dynamics; phonon density of states; pillared graphene; standing wave; thermal rectification