Sensitively tuning the thermal conductivity of diamane via engineering the mass of functional groups

Sensitively tuned thermal conductivity is highly desired for many practical applications, e.g. thermoelectricity and thermal metamaterials. Our theoretical calculations reveal that the thermal conductivities of functionalized two-dimensional (2D) materials show a rapid response to the increasing mass of functional groups, in which we take the newly synthesized diamane as an example and artificially tune the mass of hydrogen atoms to mimic the surface ligands of different masses. Our results indicate the sensitive influence of the mass of functional groups on the vibration and phonon transport properties of 2D materials. As the mass increases, the phonons are appreciably softened which results in reduced group velocities and the squeezed distribution of phonons in the frequency domain. The latter factor leads to an enlarged phonon-scattering phase space. Consequently, the intensified phonon-phonon scattering combined with the reduced group velocities could make the thermal conductivities decrease by similar to 80%. Our findings suggest an intriguing strategy to sensitively tune the thermal conductivities of 2D materials via tailoring the mass of functional groups.