Enhancing electrical conductivity of coal-derived graphite by boric acid catalysis: Correlating 2H/3R phase ratio with crystallite structure.

Abstract

Natural graphite scarcity and conventional catalyst-induced defects limit the scalable production of high-performance coal-derived graphite. Herein, we demonstrate boric acid (H3BO3) as a green catalyst for coal graphitization by comparing with Fe2(SO4)3, FeCl3, FeS2, and H3BO3+FeCl3, with a focus on crystallite structure, 2H/3R polytypic graphite, and electrical conductivity. X-ray diffraction (XRD) analysis reveals that H3BO3 catalysis significantly elevates structural order, presenting a narrow and sharp (002) band, and increasing in-plane crystallite size (La), stacking height (Lc), and the proportion of graphite (fɑ) in the bulk sample. High resolution transmission electron microscopy (HR TEM) identifies graphite-like nanostructures and planar graphene nanostructure as the key contributor to electrical conductivity. A linear relationship between La and 2H/3R is established, associated with electrical conductivity, confirming the intrinsic correlation between graphite-like nanostructures and crystalline size. This work clarifies the feasibility of boric acid, providing a low-cost and efficient strategy for fabricating high-performance coal-derived graphite, which holds great potential for applications in energy storage and conductive fields.