Comparison of secondary hydrothermal and pyrolysis in biomass carbon-based materials: activation methods and surface properties

Functional carbon-based materials play an important role in the field of energy and environmental protection, and how to prepare high-performance sustainable carbon-based materials is a current research hot spot. In this paper, the hydrothermal products of corn stover were used as precursors, and the carbon materials prepared in different ways were tested for their properties, and the synergistic effects of the two activation methods of secondary hydrothermal and pyrolysis with the catalysts were discussed. The results show that secondary hydrothermal can enrich the surface functional groups of the materials with higher product yields, but the effect on the specific surface area is weak. During pyrolysis, the content of functional groups decreases and the surface porosity increases due to the overflow of volatile matter; ZnCl₂ enhances the aromatization reaction during secondary hydrothermal process, and the specific surface area of the material is greatly increased by the etching effect during pyrolysis; both activation modes are able to realize the heterocyclic N doping through the addition of urea, and the pyrolysis process is able to produce more nitrogen-containing functional groups.