| Summary: | 碩士 === 元智大學 === 化學工程與材料科學學系 === 104 === An electrochemical route to functionalize graphene nanosheets (GNs) directly from a natural graphite electrode is described herein in the presence of sulfate ions under constant-voltage (CV) and constant-current (CC) models at temperature range of 303‒333 K. This electrochemical exfoliation process is more effective than chemical exfoliation processes and also provides a means of producing low-defect and high-yield GN products. The influence of exfoliation temperature on the quality of as-prepared GN products is systematically investigated. To clarify this effect, one mechanism, consisted of (i) ionic intercalation, (ii) anion insertion and polarization, (iii) water electrolysis and SO2 evolution, and (iv) bubble expansion, is proposed. The interlayer distance, defect concentration, and growth rate of GNs as an increasing function of exfoliation temperature can be obtained. By using only 250 ml reactor, more than 1.8 g of GNs is obtained in less than 1 h through the CC operation. The growth rate of GNs under CC model is approximately five times higher than that under CV one at the fixed temperature. Based on the analysis of Arrhenius plots, the apparent activation energies through the CV and CC models are 20.6 and 23.1 kJ/mol, respectively. As a result, this exfoliation method using the CC model displays a potentially scalable approach for generating high-quality GN products.
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