Modified graphene papers with alkaline earth metal ions endowed with high heat transfer properties

Publication date: 31 December 2015
Source:Thin Solid Films, Volume 597
Author(s): Wei Yu, Huaqing Xie, Lifei Chen, Junchang Zhao, Fengxian Li
Graphene papers (GP) modified with alkaline earth metal ions (Mg²⁺, Ca²⁺) were prepared by reduction of graphene oxide papers, which were obtained through a facile vacuum filtration of graphene oxide solution aqueous. The thermal conductive properties of graphene paper and its modified analogues were measured with a laser flash method. The thermal diffusivities of Mg-modified GP and Ca-modified GP are 1003.4mm²/s and 2232.2mm²/s, respectively, which is significantly improved compared with unmodified graphene paper (694.9mm²/s). The corresponding thermal conductivities are 100.4W/mK (GP), 147.7W/mK (Mg-GP) and 331.8W/mK (Ca-GP), respectively, from which a substantial enhancement in thermal conductivity of M-modified GP is also observed. It is found that the ion chelating between carboxyl groups of graphene oxide and alkaline earth metal ions will bridge the small graphene oxide sheets, and it will decrease the thermal resistance of the boundary and increase the contact surface of graphene sheets. The reduction of M-modified graphene oxide can partly recover the structure of graphene, thus can further improve the heat transfer property of graphene paper.