Engineered biochar as a potential adsorbent for carbon dioxide capture

Increase of atmospheric CO₂ concentration, a key driver of global warming and climate change, has become an increasing environmental and economic concern over the past decades. Biochar has been identified as a promising sorbent for capturing CO₂, owing to its low-cost, eco-friendliness, high porosity, and easiness to modify surface structure. Various strategies are used to upgrade biochars’ surface chemistry to obtain high-quality CO₂ sorbents. Modified biochars typically have higher surface areas and pore volumes, extensively developed pore structures, and more O- and N-containing functional groups than pristine biochars. Therefore engineered biochars exhibit excellent CO₂ uptakes via enhanced physisorption and inner- and outer surface complexations. Moreover, their high regeneration capacity reduces the total CO₂ removal costs. This chapter discusses different strategies for producing engineered biochars, factors affecting CO₂ adsorption capacity of pristine biochar, and challenges and future perspectives of using engineered biochar as an adsorbent for CO₂ capture.