Coherency between thermal and electrical transport of partly reduced graphene paper

Abstract

By continuously varying the structure of graphene oxide paper (PRGP) using Joule heating annealing, we are able to tune its electrical conductivity (σ) and thermal diffusivity (α) in a very wide range: more than three orders of magnitude for σ (186–503009 S/m) and 10-fold for α (8.31 × 10−7 m2/s to 9.31 × 10−6 m2/s). Excellent coherency-linear relationship between σ and α is discovered although they are sustained by different carriers: electrons and phonons. Such coherency exists over two sections: σ > 2 × 104 S/m, and 103<σ < 2 × 104 S/m. A two-component parallel structure is proposed to interpret the observed discovery. The slope of α∼σ relation reflects the ratio of difference in α between the two components over σ of the ordered structure. The intercept of α∼σ relation reflects the α of the disordered structure. It is found the α of disordered structure in our PRGP agrees well with that of amorphous carbon. Past work on carbon nanocoil, graphene paper, graphene oxide film, and graphene fiber also reveals linear coherency between α and σ. However, there are no uniform slope and intercept while they are close for similar materials. The parameters of the linear coherency strongly depend on the two structures in the material.