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We apply the non-equilibrium molecular dynamics approach (NEMD) to study thermal rectification in a hybrid graphene-carbon nitride system (G − C 3 N) under a series of positive and negative temperature gradients. In this study, the effects of temperature difference, between two baths (∆T), and sample size on thermal rectification are investigated. Our simulation results indicate positive correlation between thermal rectification and temperature difference for ∆T > 60 K, and high thermal rectification values, up to around 50% for ∆T = 100 K. Furthermore, this behavior remains practically consistent among different sample lengths. The underlying mechanism leading to a preferable direction for phonons is calculated using phonon density of states (DOS) on both sides of the G − C 3 N interface, and the contributions of in-plane and out-of-plane phonon modes in total thermal rectification are also explored.

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Optimization of thermal conductivity of nanomaterials enables the fabrication of tailor-made nanodevices for thermoelectric applications. Superlattice nanostructures are correspondingly introduced to minimize the thermal conductivity of nanomaterials. Herein we computationally estimate the effect of total length and superlattice period ($$l_{p}$$ l p ) on the thermal conductivity of graphene/graphane superlattice nanoribbons using molecular dynamics simulation. The intrinsic thermal conductivity ($$\kappa_{\infty }$$ κ ∞ ) is demonstrated to be dependent on $$l_{p}$$ l p . The $$\kappa_{\infty }$$ κ ∞ of the superlattice, nanoribbons decreased by approximately 96% and 88% compared to that of pristine graphene and graphane, respectively. By modifying the overall length of the developed structure, we identified the ballistic-diffusive transition regime at 120 nm. Further study of the superlattice periods yielded a minimal thermal conductivity value of 144 W m−1 k−1 at $$l_{p}$$ l p  = 3.4 nm. This superlattice characteristic is connected to the phonon coherent length, specifically, the length of the turning point at which the wave-like behavior of phonons starts to dominate the particle-like behavior. Our results highlight a roadmap for thermal conductivity value control via appropriate adjustments of the superlattice period.