Synthesis of biowaste-derived carbon foam for CO2 capture

• Carbon foam was obtained from biowaste by a self-foaming approach. • The aromatic segments identified by 2D NMR enhance the foaming process. • Hydrothermal and pyrolysis processes increase graphitic carbon in carbon foam. • Carbon foam shows significantly improved CO 2 uptake. • The favorable CO 2 uptake is attributed to the hierarchical 3D porous carbon. Thermal transformation of biowaste to carbon foam provides an economically attractive and eco-friendly strategy for biowaste recycling. Herein, we report a novel self-foaming approach involving modified hydrothermal carbonization (HTC) and pyrolysis to produce carbon foam from biowaste. Notably, biowaste-derived carbon foam consists of foam structure and multi-porous structure, originated from the self-forming process of aromatic segments during modified HTC and pyrolysis processes. Based on characterization results, biowaste-derived carbon foam possesses hierarchical micropore , mesopore and macropore with increasing sp 2 hybridized carbon atoms. We demonstrate the potential applications of this material for CO 2 capture. Biowaste-derived carbon foam exhibits 5.0-fold and 4.8-fold CO 2 uptake at 35 °C and 50 °C, respectively, compared to those of pristine biowaste. The recycling of biowaste to carbon foam for CO 2 capture contributes to decarbonization efforts worldwide by a synergistic way, including the photosynthesis of atmospheric CO 2 to biomass, carbon sequestration in carbon foam and CO 2 capture by carbon foam.