Biochar-based carbon nanomaterials: precursor variability and structure-property heterogeneity for energy-environmental applications

Biomass-derived carbon nanomaterials offer potential renewable alternatives to fossil-based carbon materials. It is, however, difficult to predict their performance since biomass composition, inorganic constituents, moisture, particle characteristics, and processing conditions all have strong influences on carbonization and structural evolution. The purpose of this review is to critically examine how precursor properties, carbonization/activation strategies, pore architecture, graphitic domains, defects, surface functionalities, and heteroatom configurations collectively affect the performance of materials. The paper discusses microwave-assisted pyrolysis as a rapid conversion route with distinct energy transfer and structural regulation characteristics, while also highlighting the challenges associated with energy absorption, temperature distribution, reactor design, and dielectric property reporting. The present study establishes an integrated precursor-process-structure-performance framework for biomass-derived carbon nanomaterials, in contrast to previous reviews that were primarily concerned with synthesis or applications. A standardized reporting approach and data-driven approaches are further recommended to improve reproducibility, enable reliable comparisons, and support scalable and application-oriented biochar research. Highlights Biomass can be converted into useful carbon materials for cleaner technologies There is a strong relationship between the quality and performance of materials and the raw materials used. Materials such as these are used for energy storage, carbon capture, and environmental cleanup applications.