Energy-efficient, eco-friendly, and scalable line-laser reduction process for graphene oxide in thermally conductive polymer composites

Abstract

Reducing graphene oxide (GO) for large-scale graphene production is a promising approach; however, the costeffective mass production of high-quality graphene that is suitable for industrial applications remains a challenge. This study presents an energy-efficient, eco-friendly, and scalable strategy for producing reduced GO (rGO) with superior dispersibility using a straightforward line-laser reduction process (L-rGO). This method eliminates the need for hazardous chemicals typically used in chemical reduction and is more cost-effective and time-efficient than traditional thermal reduction (H-rGO); moreover, it significantly enhances the thermal and electrical properties of GO. By modulating the laser power to 10-70% of the maximum output (16 kW), the O atomic percentage decreased significantly to 4.93% (L-rGO-70), which is comparable to that of thermally reduced GO at 1500 degrees C (H-rGO-1500; 5.40%) and 1750 degrees C (H-rGO-1750; 3.05%), resulting in partial restoration of the graphene structure and marked improvement in conductivity. Compared to the stacked multilayer H-rGO with up to 38 layers, the L-rGO powders comprised approximately two to three layers, leading to superior dispersibility in the polymer matrix. The in-plane thermal conductivity of the epoxy composite with 10 wt% L-rGO-70 (2.53 W/mK) was 11-fold higher than that of neat epoxy (0.23 W/mK) and comparable to that of the H-rGO-1500-reinforced epoxy composite (2.58 W/mK). These findings suggest that the fabrication of L-rGO is an energy-efficient, eco-friendly, and cost-effective solution for fabricating thermally conductive polymer composites. This scalable and straightforward line-laser reduction process holds significant promise for the production of high-performance graphene for advanced thermal management applications.