Graphene Acetic Acid‐Based Hybrid Supercapacitor and Liquid‐Gated Transistor

Abstract Supercapacitors and transistors are two key devices for future electronics that must combine portability, high performance, easy scalability, etc. Graphene‐related materials (GRMs) are frequently chosen as active materials for these applications given their unique physical properties that are tunable via chemical functionalization. Up to date, among GRMs, only reduced graphene oxide (rGO) showed sufficient versatility and processability in mild media, rendering it suitable for integration in these two types of devices. Here, a sound alternative to rGO is provided, namely graphene acetic acid (GAA), whose physico‐chemical features offer specific advantages. In particular, the use of a GAA‐based cathode in a zinc hybrid supercapacitor (Zn‐HSC) delivers state‐of‐the‐art gravimetric capacitance of ≈400 F g −1 at a current density of 0.05 A g −1 . Conversely, GAA‐based LGT, supported onto Si/SiO 2 , shows an ambipolar behavior in 0.1 m NaCl, featuring a clear p‐doping quantified by Dirac voltage higher than 100 mV. Such a device is successfully implemented in paper fluidics, thereby demonstrating the feasibility of real‐time monitoring.