Chemical exfoliation and microwave absorption of reduced graphene oxide synthesized from old coconut shells

In this study, chemical exfoliation with the addition of hydrochloric acid (HCl) solution of old coconut shell reduced graphene oxide (rGO) was carried out. The purpose of this study was to confirm the formation of the rGO phase and to investigate the effect of heating temperature variations and chemical exfoliation processes with the addition of HCl solution on the reflection loss value of old coconut shell rGO. The heating temperature variation is at 400°C and 700°C. Three variations of 1: 1, 1: 5, and 1:10 mole ratios are used in the mixing process of HCl with rGO. Based on the results of XRD testing, the old coconut shell charcoal has formed an rGO phase. Furthermore, VNA testing shows that the biggest reflection loss value is -8.42 dB at a frequency of 10.52 GHz achieved by the sample with the lowest electrical conductivity.