Ultralow thermal conductivity of single-atom doped carbon aerogel synthesized with a facile ambient-pressure-drying strategy

Abstract

Carbon aerogel is an attractive material for thermal insulation due to the porous character and high stability at high temperature. However, the wide application of carbon aerogel for thermal insulation is hindered by complicated supercritical-drying technology and high thermal conductivity of the pure carbon skeleton. Herein, a facile ambient-pressure-drying technology is developed for synthesizing Fe–N4 doped carbon aerogel through catalyzing the polymerization reaction of monomers under a Fe sol, with copolymer F127 as enhancement phase for wet-hydrogel. The whole process does not have any solvent exchange or aging procedure. The prepared carbon aerogel has an ultralow thermal conductivity of 0.048 W/(m ∙ K) at room temperature, with negligible 2% shrinkage during ambient-pressure-drying process and excellent mechanical behavior with stress of 0.58 MPa at 10% strain. The thermal conductivity of carbon-fiber reinforcement carbon aerogel is 0.158 W/(m ∙ K) at 1100 °C, and has an elasticity modulus of 108.3 MPa. Based on an ideal model, density functional theory calculations reveal that doping Fe–N4 can significantly enhance the anharmonicity of carbon-based materials and thus reduce the lattice thermal conductivity by more than 10 times. This work presents a facile and low-cost method for synthesizing carbon aerogel with single-atom doping for promising applications in thermal insulation.