Controllable synthesis of a robust sucrose-derived bio-carbon foam with 3D hierarchical porous structure for thermal insulation, flame retardancy and oil absorption

The fast exhaustion of the fossil fuels has led to an imperious need for more energy-efficient and environmentally friendly strategies to develop the carbon materials with high structural efficiency and multi-functional integration. Sucrose represents a promising biomass source for obtaining the carbon foams. However, the uncontrolled foaming restricts the preparation and performance of the efficient sucrose-based carbon foams. Herein, a novel route of template-free mechanical foaming-gel has been reported to fabricate the robust and multifunctional sucrose-derived carbon foams with the hierarchical porous structure. The pore structure and porosity could be flexibly controlled by tuning the sucrose concentration during the mechanical stirring process. The synergy between sucrose and epoxy hydrogel as a network skeleton endowed the carbon foams with a high carbon yield (44.7%) and optimal specific mechanical properties. The carbon foams after heat treatment at 1200 °C displayed a low density (0.089–0.195 g/cm³) and a high compression strength (1.02–4.93 MPa). The foams also exhibited excellent heat insulation performance and flame retardancy. The thermal conductivity of the carbon foam with a density of 0.089 g/cm³ was as low as 0.092 W/m·K at room temperature and 0.269 W/m·K at 1200 °C under argon atmosphere. Furthermore, the carbon foams revealed a high oil absorption capacity, together with an optimal recyclability on combustion. Meanwhile, the foams also maintained superhydrophobicity after immersion in acidic, alkaline and salty media for 120 days. The developed strategy could not only realize the preparation of the energy-efficient and environmentally-friendly bio-carbon foams with a reliable self-adaptability to the extreme environments, but also exhibited promising universality and flexibility in designing the carbon materials for applications in aerospace and oil spill cleanup.