title: Hydrogenation of Penta-Graphene Leads to Unexpected Large Improvement in Thermal Conductivity.
abstract: Penta-graphene (PG) has been identified as a novel two-dimensional (2D) material with an intrinsic bandgap, which makes it especially promising for electronics applications. In this work, we use first-principles lattice dynamics and iterative solution of the phonon Boltzmann transport equation (BTE) to determine the thermal conductivity of PG and its more stable derivative, hydrogenated penta-graphene (HPG). As a comparison, we also studied the effect of hydrogenation on graphene thermal conductivity. In contrast to hydrogenation of graphene, which leads to a dramatic decrease in thermal conductivity, HPG shows a notable increase in thermal conductivity, which is much higher than that of PG. Considering the necessity of using the same thickness when comparing thermal conductivity values of different 2D materials, hydrogenation leads to a 63% reduction in thermal conductivity for graphene, while it results in a 76% increase for PG. The high thermal conductivity of HPG makes it more thermally conductive than most other semiconducting 2D materials, such as the transition metal chalcogenides. Our detailed analyses show that the primary reason for the counterintuitive hydrogenation-induced thermal conductivity enhancement is the weaker bond anharmonicity in HPG than PG. This leads to weaker phonon scattering after hydrogenation, despite the increase in the phonon scattering phase space. The high thermal conductivity of HPG may inspire intensive research around HPG and other derivatives of PG as potential materials for future nanoelectronic devices. The fundamental physics understood from this study may open up a new strategy to engineer thermal transport properties of other 2D materials by controlling bond anharmonicity via functionalization.
authors.affiliation: Aerospace and Mechanical Engineering, University of Notre Dame , Notre Dame, Indiana 46530, United States.
authors.forename: Xufei
authors.initials: X
authors.lastname: Wu
authors.affiliation: Materials and Manufacturing Directorate, Air Force Research Laboratory , Wright-Patterson Air Force Base, Ohio 45433, United States.|Universal Technology Corporation , Dayton, Ohio 45342, United States.
authors.forename: Vikas
authors.initials: V
authors.lastname: Varshney
authors.affiliation: Materials and Manufacturing Directorate, Air Force Research Laboratory , Wright-Patterson Air Force Base, Ohio 45433, United States.|Universal Technology Corporation , Dayton, Ohio 45342, United States.
authors.forename: Jonghoon
authors.initials: J
authors.lastname: Lee
authors.affiliation: Aerospace and Mechanical Engineering, University of Notre Dame , Notre Dame, Indiana 46530, United States.
authors.forename: Teng
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Materials and Manufacturing Directorate, Air Force Research Laboratory , Wright-Patterson Air Force Base, Ohio 45433, United States.|Universal Technology Corporation , Dayton, Ohio 45342, United States.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Wohlwend
authors.affiliation: Materials and Manufacturing Directorate, Air Force Research Laboratory , Wright-Patterson Air Force Base, Ohio 45433, United States.
authors.forename: Ajit K
authors.initials: AK
authors.lastname: Roy
authors.affiliation: Aerospace and Mechanical Engineering, University of Notre Dame , Notre Dame, Indiana 46530, United States.|Center for Sustainable Energy at Notre Dame , Notre Dame, Indiana 46530, United States.
authors.forename: Tengfei
authors.initials: T
authors.lastname: Luo
keywords: Penta-graphene; anharmonicity; first-principles calculation; graphene; hydrogenated penta-graphene; thermal conductivity