Molecular dynamics study of electric-field-assisted boiling heat transfer of copper nanofluids on Cu–graphene nanostructured surfaces

Phase-change thermal management at nanoscale interfaces is strongly influenced by interfacial energy transport, bubble nucleation, and fluid–surface interactions. The combined use of nanofluids, nanostructured surfaces, and external electric fields provides a promising strategy for boiling heat transfer enhancement, but the underlying atomic-scale coupling mechanism remains insufficiently understood. In this study, molecular dynamics simulations were performed to investigate electric-field-regulated boiling of copper nanofluids on a nanostructured Cu–graphene hybrid surface. Two nanoparticle radii, 1.985 and 2.708 nm, were considered under a fixed particle-number configuration, corresponding to different nanoparticle volume fractions. The results show that the smaller-particle system exhibits earlier nucleation and a stronger later-stage thermal response than the larger-particle system, which may be associated with enhanced particle mobility, more uniform energy redistribution, and easier activation of preferential nucleation regions at the heterogeneous interface. The electric-field effect is strongly dependent on the nanoparticle configuration. For the larger-particle system, the sinusoidal field provides the most evident enhancement, whereas the DC fields show limited or slightly adverse effects. For the smaller-particle system, electric fields do not necessarily advance nucleation onset, but they improve later-stage energy uptake, fluid temperature, and evaporation intensity. Increasing the frequency of the sinusoidal field from 0.05 to 0.3 THz progressively advances nucleation and promotes bubble growth within the investigated range. Local energy mapping and nanoparticle trajectory analysis suggest that the observed enhancement arises from electric-field-induced modulation of interfacial water structure, energy redistribution, and particle–fluid interactions near the heterogeneous Cu–graphene interface. These findings provide atomistic insights into the coupled regulation of nanofluid boiling heat transfer by surface nanostructures and external electric fields.