Waste biomass-derived biochar in adsorption-photocatalytic conversion of CO2 for sustainable energy and environment: Evaluation, mechanism, and life cycle assessment

Biochar is an environmentally friendly material with great potential for carbon capture and storage. As the first of its kind, waste biomass-derived biochar was utilized to convert CO2 into fuel in solar. Herein, among four representatives herbaceous, woody, sludge, and manure wastes, the pine sawdust-derived biochar produced the highest CO assisted by higher CO2 adsorption, more than 10 times higher than that of graphene and activated carbon. The function groups of carbonyl and carboxyl on biochar controlled the CO2 capture and solar conversion by decreasing adsorption and activation energies of CO2 molecules. The biochar performed even better for 15% CO2/N2 atmosphere, a typical CO2 concentration in the flue gas, demonstrating its promising potential in waste gas resource utilization. The life-cycle assessment indicates that feedstock with more cellulose and lignin provide better environmental and economic benefits. The work highlights a sustainability pathway for waste biomass-derived biochar in CO2-to-fuel under ambient conditions.