Nitrogen, Sulfur Co-doped Carbon Materials Derived from the Leaf, Stem and Root of Amaranth as Metal-free Catalysts for Selective Oxidation of Aromatic Hydrocarbons

Development of porous heteroatom-doped carbon materials from plant biomass is of great significance for various applications in environment, energy conversion and catalysis process. However, the different natures of carbon materials derived from the leaf, stem and root of the same plant biomass are rarely reported. Herein, we synthesized porous carbon materials from the leaf, stem and root of amaranth respectively by pyrolysis without any activation treatment. Detailed characterizations indicated that these three carbon materials all had nitrogen, sulfur doped atoms and similar degree of graphitization, but showed distinct differences in the pore structures and surface compositions. We suggested these differences were contributed by the different contents of ashes, vascular bundles and proteins in different parts. When used as metal-free carbocatalysts for the oxidation of aromatic hydrocarbons, stem-derived carbon (SDC-A) exhibited the highest catalytic performance due to its high surface area, profitable pore volume and rich doped heteroatoms. Moreover, the carbocatalysts derived from the leaf, stem and root of pumpkin vine and coriander showed similar activity differences in oxidation of aromatic alkanes, implying the present results have a certain extent generality, and provide a new guidance for preparing carbon materials from plant biomass.