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Varied graphene sheets were prepared from the graphite oxide (GO) with different degrees of oxidation and furthermore their structural characteristics and electrochemical properties as anode materials for Li-ion batteries were investigated. From the expandable graphite with a low oxidation level, the obtained graphene sheets had a thick and intact sheet structure with good crystallinity. Its specific surface area was quite low and no porous structure was detected. The graphene sheets prepared from the GO precursor with a high degree of oxidation were quite thin and disordered, along with high specific surface area and plenty of pores. These ultrathin graphene sheets demonstrated high reversible capacity mainly in the way of lithium absorption, where the specific surface area was the key structural parameter. The thick graphene sheets prepared from the expandable graphite had good crystallinity with few defects and pores, and had a similar lithium storage mechanism to graphite, whereby lithium storage is carried out by intercalation reactions.

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Carbon dioxide sequestration on coal with enhanced coalbed methane recovery (CO 2 -ECBM) is acknowledged as a promising way to mitigate CO 2 emissions. For successfully understanding and implementing CO 2 -ECBM process, the potential interactions of CO 2 with coal during CO 2 sequestration in coal seams were investigated. Research methods consisting of lowtemperature nitrogen adsorption−desorption and chromatographic analysis were used to address the transformation of coal pore morphology and the capability of supercritical CO 2 extraction when coal contacts with high pressure CO 2 . According to the test results, interaction of coal with high pressure CO 2 does not create a significant influence on pore shape and mesoporous volume distribution of any rank of coal. However, this causes the coal surface fractal dimension and specific surface area to be changed, which implies that the coal's pore morphology change due to CO 2 sorption is irreversible. The results also indicate that the injection of high-pressure CO 2 does not only change the pore morphology of coal but also has the ability to extract the hydrocarbons present in the coal matrix. The extracted hydrocarbons are of biological toxicity and can be mobilized with gas or water to other geologic structures and aquifers. Thus, the potential environmental safety and health issues (ES&H issues) related to CO 2 sequestration in deep coal seams require thorough assessment.

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