Robust and multifunctional sucrose-derived biocarbon aerogel reinforced by CNTs for integrated mechanical property, thermal insulation and oil adsorption

Driven by the "dual carbon" goal and demand for fossil carbon alternatives, biocarbon aerogels have become a research focus for their renewability and environmentally friendly. However, most biocarbon aerogels suffer from uncontrollable pore structure, huge high-temperature volume shrinkage and poor performance synergy. Herein, chitosan (CS) and sucrose were used as the carbon skeleton to fabricate green sucrose/CS/carbon nanotube (CNTs) composite biocarbon aerogels via freeze-drying and high-heat treatment. CS’s 3D cross-linked network effectively suppressed the uncontrolled foaming of sucrose, thus enabling precise microstructure regulation of the composite biocarbon aerogel. By utilizing the structural support of CNTs, the composite biocarbon aerogel achieved simultaneous optimization of the mechanical and thermal insulation performance. After heat-treated at 1200 °C, the composite biocarbon aerogel exhibited low density (0.0773–0.1226 g/cm³), high porosity (87.66%–91.88%), excellent compressive strength (0.77–12.09 MPa) and a maximum specific compressive strength of 17.79 MPa·cm³·g⁻¹. Besides, the thermal conductivity reached as low as 0.0648 W/m·K at 25 °C, and only raised to 0.1644 W/m·K at 900 °C. Moreover, the material also showed high oil absorption capacity and ideal combustion recyclability. The synergistically multifunctional composite carbon aerogels exhibit application potential in aerospace thermal insulation and oil spill remediation, offering insights for designing multifunctional biomass carbon aerogels.