Synthesis of nitrogen-doped reduced graphene oxide with enhanced electrical conductivity for RF antenna applications

초록

A low-frequency radio frequency (RF) antenna electrode based on nitrogen-doped reduced graphene oxide (NrGO) was developed, exhibiting enhanced electrical conductivity and long-term operational stability. The NrGO material was synthesized through a three-step process: solvent exchange of graphene oxide (GO), hydrothermal doping with a donor-acceptor complex, and hydrazine vapor-phase reduction. To improve doping efficiency, 4-nitroaniline reacted with maleic anhydride to form a nitrogen-containing donor-acceptor complex with an imide linkage, which was subsequently grafted onto GO via a Diels-Alder reaction. The resulting NrGO was processed into antenna electrodes using a screen printing technique. Surface resistance remained within the range of 50-60 Omega/sq regardless of electrode dimensions, with the lowest value (similar to 50 Omega/sq) achieved at 9 wt% NrGO. This composition also demonstrated excellent long-term stability over six months. The printed electrodes enabled precise frequency tuning, with the optimized antenna operating at a mean frequency of 1.23 GHz, return loss of -21.2 dB, a bandwidth of 200 MHz, and a radiation efficiency of 40.4 %. These results indicate that NrGO based RF antenna electrodes offer strong potential for integration into next-generation Internet of Things (IoT) systems and emerging low-frequency wireless communication technologies.

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