Abstract
In this study, we fabricate bendable solid-state supercapacitors with Au nanoparticle (NP)-embedded graphene hydrogel (GH) electrodes and investigate the influence of the Au NP embedment on the internal resistance and capacitive performance. Embedding the Au NPs into the GH electrodes results in a decrease of the internal resistance from 35 to 21 Ω, and a threefold reduction of the IR drop at a current density of 5 A/g when compared with GH electrodes without Au NPs. The Au NP-embedded GH supercapacitors (NP-GH SCs) exhibit excellent capacitive performances, with large specific capacitance (135 F/g) and high energy density (15.2 W·h/kg). Moreover, the NP-GH SCs exhibit comparable areal capacitance (168 mF/cm2) and operate under tensile/compressive bending.
Highlights
Investigated the existence of Au NPs in the compressed graphene sheets as well as the surface and cross-sectional morphologies by a high-resolution scanning electron microscopy (HR-SEM)
The supercapacitors made of Graphene hydrogel (GH) with and without Au NPs are referred to as NP-GH and GH supercapacitors (SCs), respectively
The physical properties of GH and NP-GH composites were examined by x-ray diffraction (XRD) spectroscopy (Bruker, D8 Focus), Raman spectroscopy (Horiba Jobin Yvon, LabRam ARAMIS IR2) and x-ray photoelectron spectroscopy (XPS; AXIS ULTRADLD spectrophotometer)
Summary
Investigated the existence of Au NPs in the compressed graphene sheets as well as the surface and cross-sectional morphologies by a high-resolution scanning electron microscopy (HR-SEM) (supplementary information). The NP-embedded GH electrodes were dipped into the (1 M) H3PO4-PVA aqueous solution, and air-dried at 50 °C for 2 h, to evaporate the excess water. To investigate the effect of embedding Au NPs in the GH electrode, we prepared a supercapacitor using GH without Au NPs, to be used as a reference sample. Three NP-GH SCs were assembled in series to confirm that the connected NP-GH SCs were able to turn on a red light-emitting diode (LED) with a minimal operating turn-on potential of 2.7 V
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