New insights in graphene oxide dielectric constant

Extensive research on the investigation of properties of graphene-based materials exhibit a large dispersion of values for the dielectric constant ε; for graphene oxide (GO), reported ε values range from 2 to 10⁶. In this regard, we aim to study in detail GO's ε by in situ temperature XRD, FTIR, impedance measurements and TGA in wet and dry samples. Our findings reveal that ε's GO strongly depends upon the frequency range and moisture content; here, we report 3 frequency regimes: (1) 10⁴ < ε < 10⁶; 1 < f < 600 Hz dominated by Wartburg pseudocapacitance; (2) 10⁴ < ε < 10²; 5 × 10² < f < 2 × 10⁵ Hz dominated by GO groups-water interface layer ; and (3) 30 < ε < 50; 5 × 10⁵ < f < 5 × 10⁷ Hz dominated by bulk GO properties. In summary, our findings reveal a more complex phenomena that dominates the dielectric constant in GO which can be advantageously used in the design of advanced materials. (paper)