PUBLICATION: JOURNAL OF MATERIALS SCIENCE

AUTHORS: Huang, Q; Li, RC; Li, C; Huang, HF; Zhou, XT

 

The depth-dependent structural changes in oxidized graphite have not been precisely revealed because of its friable nature. Here, micro-focused X-ray diffraction is used to measure the structural changes of oxidized graphite. An improved polishing method is then applied to observe the friable microstructures via scanning electron microscope. The (002) peak intensity and peak width is found to be very sensitive to local weight loss. The peak width decreases with the increase of weight loss, indicating an oxidation-induced increase of the average coherent length. High-resolution depth profiles of oxidized graphite structures are obtained for the first time. A double-layer oxidation mechanism is revealed. In the inner oxidation layer, oxidation happened preferentially to the binder regions and defective filler particles and leaves complicated paths which greatly increased the active surface area. It is observed that the original pore structures maintained in the inner oxidation layer. The outer oxidation layer showed a depletion of the binder regions and was oxidized in a much slower rate. However, the graphite grains could fall off easily, which causes a rapid drop of (002) peak intensity at the very surface.

 

LINKS: http://dx.doi.org/10.1007/s10853-022-07044-8