Comment on "Spontaneous heat current and ultra-high thermal rectification in asymmetric graphene: a molecular dynamics simulation"

Recently, Yousefi et al (2025 Nanotechnology 36, 135401) report simulations of a graphene thermal rectifier which apparently predict ultra-high thermal rectification and a spontaneous heat current. We show that these results originate from an off-set in the predicted dependence of heat current on temperature difference which contravenes accepted laws of thermodynamics and so is presumably an artefact of the modelling procedure employed in the study.