Lightweight Carbon From Lightweight Biomass: A Nature-Inspired Carbon Nexus for Smart Applications.

Carbon materials with low density often exhibit such a low mass that they surpass many of the lightest natural substances. This exceptionally low density is typically achieved when the carbon material possesses specific structural properties, such as high porosity, a 3D surface morphology, and a large surface area. Additionally, these materials often take on forms like foam, spongy, or tubular shapes, which leads significantly to their reduced density. The lightweight properties associated with these structural characteristics also confer several other important traits, including high chemical stability, low thermal conductivity, and high electrical conductivity, etc., which make them suitable for a large variety of applications, including those in environmental remediation, energy storage and conversion, and the production of lightweight compressible materials, thermal insulating materials, and also electromagnetic shielding material. Biomass-derived carbon materials offer several intrinsic advantages, including sustainability, porous structures, high conductivity, hydrophobicity, ease of modification, and diverse chemical composition. Many biomass precursors, whether plant- or animal-based, are naturally lightweight and contribute significantly to the development of carbon materials with tailored architectures and properties. Thus, nature inspires materials scientists to adopt strategic approaches in designing lightweight carbon materials. Lightweight biomass enables the efficient synthesis of lightweight carbon materials, making it an ideal choice for reducing density while maintaining excellent structural performance. This article presents a comprehensive review covering biomass precursors for carbon preparation, key properties that reduce carbon density and make it exceptionally lightweight, and the various synthesis routes used to produce such carbon materials. Recent progress in the versatile applications of biomass-derived lightweight carbon materials, based on their morphologies and physicochemical properties, is also reviewed. The perspectives on future challenges and research opportunities in lightweight carbon materials are outlined.