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A series of flexible and self-standing coal-derived carbon fibers (CCFs) were fabricated through electrospinning coupled with carbonization using bituminous coal and polyacrylonitrile (PAN) as the carbon precursors. These CCFs were utilized as free-standing lithium-ion battery (LIB) anodes. Optimizing carbonization temperature reveals that the CCFs exhibit a one-dimensional solid linear structure with a uniform distribution of graphite-like microcrystals. These fibers possess a dense structure and smooth surface, with averaging diameter from approximately 125.0 to 210.0 nm at carbonization temperatures ranging from 600 to 900 °C. During electrospinning and carbonization, the aromatic rings enriched in bituminous coal crosslink with PAN chains, forming a robust three-dimensional (3D) framework. This 3D microstructure significantly enhances the flexibility and tensile strength of CCFs, while increasing the graphite-like sp2 microcrystalline carbon content, thus improving electrical conductivity. The CCFs carbonized at 700 °C demonstrate an optimal balance of sp3 amorphous and sp2 graphite-like carbons. The average diameter of CCFs-700 is 177 nm and the specific surface area (SSA) is 7.2 m2·g−1. Additionally, the fibers contain oxygen-containing functional groups, as well as nitrogen-containing functional groups, including pyridinic nitrogen and pyrrolic nitrogen. Owing to its characteristics, the CCFs-700 showcases remarkable electrochemical performance, delivering a high reversible capacity of 631.4 mAh·g−1. CCFs-700 also exhibit outstanding cycle stability, which retains approximately all of their first capacity (400.1 mAh·g−1) after 120 cycles. This research offers an economical yet scalable approach for producing flexible and self-supporting anodes for LIBs that do not require current collectors, binders and conductive additives, thereby simplifying the electrode fabrication process.

The natural flake graphite (GO) with an initial fixed carbon content of 6.23% is purified using flotation combined with alkali-melting acid leaching to obtain the high purity graphite (PG3) for energy storage. The graphite concentrate (PG1) with fixed carbon content of 85.62% is obtained by the selective enrichment of GO particles based on the multi-stage flotation. The alkali-melting acid leaching purification method is used to further purify the PG1 to obtain the PG3 with the fixed carbon content of 99.93%. The fixed carbon content is increased by 93.7% through flotation combined with alkali solution and acid leaching. The purification process of GO is systematically evaluated and analyzed by the several characterization techniques. The impurities removal mechanisms are also analyzed, which indicates that silicate and quartz in GO react with sodium hydroxide to form soluble substances, resulted in impurities removal. Oxide in GO and hydroxide formed in the alkali-melting process are subsequently removed in acid leaching process. The obtained PG3 could be used in lithium ion battery with a higher reversible capacity of 387 mAh g−1 compared to the 345 mAh g−1 of commercial layered graphite, which has promising potential application in energy storage. The above analysis indicates that the low purity GO is converted into high purify PG3 for energy storage, realizing high quality utilization of GO.

Wood waste is employed as the feedstock for production of high-quality pyrolysis products such as bio-oil, bio-gas and biochar by microwave pyrolysis using ZnCl2 and Fe(NO3)3 as additive at 400–800 °C. Pyrolysis temperature influences the yield of the pyrolysis products, which indicates that the yield of bio-gas increases and the yield of biochar decreases as pyrolysis temperature increases. The yield of the bio-oil is little influenced by pyrolysis temperature, which is restrained in the existence of ZnCl2 and Fe(NO3)3. ZnCl2 increases the furfural content in bio-oil. While Fe(NO3)3 promotes H2 production during pyrolysis process. The maximum heating value of bio-gas produced at 800 °C is 12.26 MJ/Nm3. The added ZnCl2 and Fe(NO3)3 increase the yield of the biochar, which also promote the formation of pore structure of biochar. The ZnCl2 and Fe(NO3)3 are converted into ZnO and Fe3O4 onto biochar after pyrolysis, which could be used as the absorbent and photocatalyst for methyl orange removal.

Camellia oleifera shell is used as the feedstock to prepare the valuable products by pyrolysis using microwave heating at 400-800 °C. The yield of pyrolysis product is influenced by pyrolysis temperature, which indicates that high pyrolysis temperature promotes to generate bio-gas and restrains the production of biochar. However, pyrolysis temperature little influences the yield of bio-oil. The main compound of bio-oil is phenols, hydrocarbons, ketones, aldehydes and furans, respectively. While, bio-oil produced at 600 °C has as high as 78 % of phenols, which has potential application in chemical industries. The pyrolysis temperature has significantly influenced the composition and heating value of bio-gas. The maximum heating value of bio-gas is 12.44 MJ/Nm3, which is achieved at 600 °C. The physiochemical properties of biochar are also influenced by pyrolysis temperature. Biochar could be used as an adsorbent to adsorb Ag+ from aqueous solution, which is formed the value-added ABiochar composite by reduction. The adsorption and reduction process of Ag+ are investigated. While, ABiochar composite can be used as the catalyst for methylene blue degradation. ABiochar composite can be also used in the lithium ion battery cathode material for energy storage.