Macroscopic 3D graphene has gained significant attention for advanced applications, including wearable electronics, thin-film batteries, soft robotics, and bioinspired surfaces. While laser-induced graphene (LIG) offers advantages such as design flexibility and scalability over traditional methods (e.g., liquid assembly or catalytic templating), its geometric complexity and size remain limited by conventional lay-up or template-based approaches. Additive manufacturing (AM) has emerged as a powerful strategy for fabricating graphene structures with arbitrary shapes and enhanced functionalities. By integrating LIG with AM (LIG-AM), we present a novel approach to fabricating 3D LIG macrostructures with high efficiency, scalable freedom, and multifunctional capabilities for diverse applications. In this work, we develop two LIG-AM strategies that overcome existing limitations and enable versatile 3D graphene architectures.

The first LIG-AM protocol utilizes laminated object manufacturing (LOM) technology to construct 3D LIG macrostructures through layer-by-layer stacking of LIG papers (LIGPs) combined with resin infiltration and hot pressing. Unlike conventional template-induced or on-site lay-up approaches, this method uniquely enables the preparation of freestanding LIGP layers with efficient AG80 resin infiltration, facilitating the fabrication of 3D LIG structures with scalable dimensions and customizable geometries. The resulting LIGP/epoxy laminated composites (LIGP-C) demonstrate exceptional manufacturability, achieving large areas (~400 cm²), substantial thickness (~3.5 mm), and adaptable flat/curved configurations. Systematic optimization of the manufacturing process has yielded composites with outstanding multifunctionality, including remarkable piezoresistive performance evidenced by a 3900% enhancement in gauge factor (from 0.39 to 15.7) while maintaining excellent mechanical strength (24.7 MPa) and electrical conductivity (143 S/m). These superior properties, attributed to the hot-press induced fusion layers, enable effective strain distribution monitoring in structural applications.

Furthermore, we developed innovative LIG-based smart honeycombs (LIG-HC) using LOM technology by alternately stacking LIG layers with thermoplastic polyurethane adhesives. This approach provides unprecedented control over structural design parameters, including overall dimensions, cell sizes/shapes, and graphene cluster patterning. The optimized LIG-HC exhibits exceptional multifunctional characteristics: anisotropic mechanical properties (e.g. 6.51±0.43 MPa of T-directional compressive strength), electrical conductivity (e.g. 1.34±0.08 S m^-1 of T-directional conductivity), piezoresistive sensitivity (e.g. 13.5 of T-directional gauge factor), electromagnetic performance (e.g. 37.6 dB of SE_Total and -20.01 dB of RL), and ultralight density (0.058±0.002 g/cm³). To demonstrate practical utility, we fabricated an intelligent aircraft-wing model incorporating these honeycombs that simultaneously achieves anti/de-icing, high-temperature warning, flame retardancy, pressure/vibration detection, and electromagnetic shielding/stealth capabilities.

The second LIG-AM protocol employs selective laser sintering (SLS) technology to fabricate complex 3D graphene structures through simultaneous particle sintering and graphene conversion of polyimide (PI) powder layers. This binder-free, template-independent approach enables the creation of diverse freeform structures, including uniform-section, variable-section, and unique graphene/PI hybrid configurations with arbitrary geometric complexity. Through systematic investigation of the coupled graphitization and fusion mechanisms, we optimized processing parameters (laser power and powder thickness) to balance manufacturing efficiency with structural resolution. The resulting 3D graphene structures exhibit tunable electrical, mechanical, and functional properties, including piezoresistance, liquid sensing, and Joule heating capabilities. To demonstrate these multifunctional characteristics, we fabricated an aircraft-wing section model showcasing directional force sensing, anti/de-icing, and microwave shielding/absorption - all enabled by the material's adaptable printing strategy and hybridizable structure.

Building upon this foundation, we developed an innovative hybrid powder-based manufacturing method for producing 3D biomass-derived LIG (B-LIG) structures from sustainable waste materials: sodium lignosulfonate (black liquor) and polypropylene (white pollution). This computer-guided laser process creates customizable macrostructures with controlled microporosity, achieving specific surface areas up to 485.3 m²/g. By optimizing laser parameters and feedstock ratios, we established precise control over structural formability and processing efficiency. The resulting B-LIG demonstrates exceptional environmental and energy applications, including pollutant adsorption (with a maximum adsorption capacity of 283.3 mg g^-1 for MB) and energy storage (with a gravimetric specific capacitance value of 194.9 F g^-1). This green, scalable production method represents a significant advancement in sustainable graphene manufacturing with both scientific and commercial potential.
 

Additive manufacturing,3D graphene macrostructures,laser-induced graphene,multifunctional structures,smart composites