National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, ‡Collaborative Innovation Center of Nano Functional Materials and Applications of Henan Province, and §College of Chemistry and Chemical Engineering, Henan University , Kaifeng 475004, China.
ACS Appl Mater Interfaces. 2017 Oct 4;9(39):34456-34466. doi: 10.1021/acsami.7b09891. Epub 2017 Sep 22.
A novel electrochemical exfoliation mode was established to prepare graphene sheets efficiently with potential applications in transparent conductive films. The graphite electrode was coated with paraffin to keep the electrochemical exfoliation in confined space in the presence of concentrated sodium hydroxide as the electrolyte, yielding ∼100% low-defect (the D band to G band intensity ratio, I/I = 0.26) graphene sheets. Furthermore, ozone was first detected with ozone test strips, and the effect of ozone on the exfoliation of graphite foil and the microstructure of the as-prepared graphene sheets was investigated. Findings indicate that upon applying a low voltage (3 V) on the graphite foil partially coated with paraffin wax that the coating can prevent the insufficiently intercalated graphite sheets from prematurely peeling off from the graphite electrode thereby affording few-layer (<5 layers) holey graphene sheets in a yield of as much as 60%. Besides, the ozone generated during the electrochemical exfoliation process plays a crucial role in the exfoliation of graphite, and the amount of defect in the as-prepared graphene sheets is dependent on electrolytic potential and electrode distance. Moreover, the graphene-based transparent conductive films prepared by simple modified vacuum filtration exhibit an excellent transparency and a low sheet resistance after being treated with NHNO and annealing (∼1.21 kΩ/□ at ∼72.4% transmittance).
建立了一种新颖的电化学剥离模式，可高效制备石墨烯片，有望应用于透明导电薄膜。在浓氢氧化钠作为电解质的存在下，石墨电极被石蜡覆盖，以保持电化学剥离在有限的空间内进行，得到了约 100%低缺陷（D 带与 G 带强度比，I/I = 0.26）的石墨烯片。此外，首次使用臭氧测试条检测到臭氧，并研究了臭氧对石墨箔剥离和所制备石墨烯片微观结构的影响。结果表明，在部分涂有石蜡的石墨箔上施加 3 V 低电压时，涂层可以防止插层不足的石墨片过早地从石墨电极剥落，从而以高达 60%的产率获得少层（<5 层）多孔石墨烯片。此外，电化学剥离过程中产生的臭氧在石墨的剥离中起着至关重要的作用，并且所制备的石墨烯片中的缺陷数量取决于电解电位和电极距离。此外，通过简单的改进真空过滤制备的基于石墨烯的透明导电薄膜在经过 NHNO 处理和退火后（在约 72.4%的透光率下，电阻约为 1.21 kΩ/□）表现出优异的透明度和低面电阻。
