Wide-angle X-ray scattering combined with pair distribution function analysis of pyrolyzed wood

A combination of wide-angle X-ray scattering (WAXS) and pair distribution function analysis was used to investigate the structural changes occurring in beech wood and apricot tree pruning samples during slow and fast pyrolysis up to 1400 degrees C (1673K). WAXS curve modeling with the program CarbX provides unique information about the arrangement of graphene layers described by intralayer, interlayer, disorder and dispersion structural parameters. Pair distribution function modeling in PDFgui revealed imperfections in single graphene sheets, such as bond shortening and curvature, when refinement is performed in different r ranges. The concentration of inorganic species, along with heating rate, influences the final structure of pyrolysis products. The heating rate was more important than sample composition for an increase in extent of the single graphene layer and average chord length, while the average graphene coherent stack height depended on both composition and heating rate. Higher fractions of inorganic material increased the average interlayer spacing and the number of graphene layers per stack.