Interfacial ion regulation on 2D layered double hydroxide nanosheets for enhanced thermal insulation

Exploring new strategies to broaden the upper/lower limit of thermal conductivity is of great interest to develop thermal management materials that can adapt to extreme environments. In this work, we employ an interfacial ion regulation to enhance the thermal insulation performance of 2D layered double hydroxide nanosheets. The introduction of interfacial ion enlarges the interplanar spacing of Co(OH)2 nanosheets from 4.64 to 8.05 Å, which reduces phonon scattering length perpendicular to the two-dimensional plane and leads to enhanced interlayer thermal insulation. The interfacial ion-regulated Co(OH)2 (named as Co(OH)2-Mx−) exhibits 3-fold enhancement of thermal insulation through decreasing the thermal conductivity to as low as 0.15 W m−1 K−1, which is among the top values in 2D solid materials. We anticipate that interfacial ion regulation for 2D nanosheets paves a new avenue to break through the thermal insulation limit.