Synthesis of biowaste-derived carbon foam for CO₂ capture

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 CO2 capture. Biowaste-derived carbon foam exhibits 5.0-fold and 4.8-fold CO2 uptake at 35 C-o and 50 C-o, respectively, compared to those of pristine biowaste. The recycling of biowaste to carbon foam for CO2 capture contributes to decarbonization efforts worldwide by a synergistic way, including the photosynthesis of atmospheric CO2 to biomass, carbon sequestration in carbon foam and CO2 capture by carbon foam.