**3. Results and Discussion**

*3.1. Solid-State Impedance Spectroscopy*

3.1.1. Capacitance and Impedance/Resistance

The degree of (*Cp*) and (*Z*) of the GRGC specimens can be perceived in Figure 2a,b. At a lower frequency (10<sup>1</sup> Hz), higher capacitance values ranging from 9.26 × <sup>10</sup>−<sup>10</sup> to

4.5 × <sup>10</sup>−<sup>9</sup> were obtained, but the (*Cp*) values tend to drop and become constant (almost zero) at higher frequencies (i.e., specifically after 103 Hz). The incorporation of GO in the geopolymer composites results in higher (*Cp*) values, whereas in an opposite trend, lower (*Z*) was observed with a higher dosage of GO (4.36 × 105 <sup>Ω</sup>). The impedance of all geopolymer composites became almost constant at higher frequencies, but higher impedance values were observed at lower frequencies for GRGC0 specimens with no addition of GO (5.32 × 106 <sup>Ω</sup>). This could suggest that GRGC4 specimens offer minimal resistance and accelerate the movement of ions in the GRGC matrix in contrast with the GRGC0 specimen. This could also be signified by the acceleration effect of GO on the polycondensation reaction of the geopolymer composites [7]. The reduction in functional groups from GO may have enhanced the electrical conductivity properties of reduced GO (i.e., rGO), as similarly noted in the study by Saffi et al. [20].
