Remarkable Effects of an Electrodeposited Copper Skin on the Strength and the Electrical and Thermal Conductivities of Reduced Graphene Oxide-Printed Scaffolds.

Architected Cu/reduced graphene oxide (rGO) heterostructures are achieved by electrodepositing copper on filament-printed rGO scaffolds. The Cu coating perfectly contours the printed rGO structure, but isolated Cu particles also permeate inside the filaments. Although the Cu deposition conveys a certain mass augment, the three-dimensional (3D) structures remain reasonably light (bulk density ≅ 0.42 g·cm). The electrical conductivity (σ) of the Cu/rGO structure (∼8 × 10 S·m) shows a notable increment compared to σ of the rGO structure (∼2 × 10 S·m). The effect on the scaffold robustness is also notable with an increase of the compressive strength by nearly 10 times (from 20 kPa of the rGO scaffold to 150 kPa of the Cu/rGO structure) and cyclability as well. The improved thermal conductivity of the Cu-coated scaffolds (∼4 times higher), in addition to the σ and strength improvements, suggests that 3D Cu/rGO structures could be suitable assemblies for integration into thermal dissipation systems, particularly as thermal interface materials, for compact electronic devices.