A comprehensive review of biomass torrefaction as a versatile platform for the synthesis of functional carbon materials

Biomass torrefaction, a mild pyrolysis process at 200–300 °C under an inert atmosphere, has emerged as a pivotal pretreatment technology for solid biowaste conversion and functional carbon materials production. This process fundamentally transforms raw biomass through deoxygenation and aromatization, with improved material properties. The chemical composition and structural heterogeneity of the biomass feedstock significantly influences the deoxygenation and aromatization pathways during torrefaction, thereby tuning the pore structure, surface chemistry, and electrochemical performance of the resulting carbon materials. This engineered intermediate is highly amenable to subsequent activation and functionalization, enabling the synthesis of high-value carbon materials. Torrefaction-derived porous biochar exhibits exceptional performance as electrodes in supercapacitors, delivering high specific capacitance and cycling stability due to its hierarchical pore structure and tunable surface chemistry. Furthermore, these materials serve as highly efficient adsorbents for pollutants and, when doped with heteroatoms or metals, as potent catalysts for degrading organic contaminants via advanced oxidation processes. In the biomedical field, controlled carbonization yields biocompatible carbon quantum dots for bio-imaging and drug delivery. The current research frontier is shifting toward multifunctional composites, such as magnetically separable catalysts and 3D-printable conductive inks. By providing a versatile and sustainable platform for precursor engineering, biomass torrefaction effectively bridges the gap between abundant renewable resources and the pressing demand for high-performance, sustainable materials across energy, environmental, and biomedical sectors. This review comprehensively summarizes the current research progress and forecasts the future trend to contribute a potential solution with great practical significance.