Enhanced electrochemical performances of polypyrrole/carboxyl graphene/carbon nanotubes ternary composite for supercapacitors

A novel strategy is proposed to obviously enhance the electrochemical capacitive properties of polypyrrole/graphene oxide/carbon nanotubes (PPy/GO/CNT) ternary composite. Here GO is treated by carboxylation reaction to obtain carboxyl graphene (CG). For comparison, PPy/GO/CNT and PPy/CG/CNT composites are synthesized with the same one-pot electro-co-deposition. Fourier transform infrared spectrometry, energy-dispersive X-ray spectroscopy, X-ray diffraction, scanning and transmission electron microscopy are carried out to characterize the composition and morphology of both composites. Unlike only utilizing the edged carboxyl groups on GO to combine with PPy coating, the current PPy/CG/CNT composite makes use of carboxyl groups distributed on basal planes and edges of CG nanosheets to combine with PPy. Accordingly, electrochemical measurements indicate that the PPy/CG/CNT electrodes markedly improve the supercapacitive properties compared to PPy/GO/CNT electrodes. The as-prepared PPy/CG/CNT composite electrodes show a high areal specific capacitance of 196.7 mF cm−2 at the current density of 0.5 mA cm−2 and superior rate capability, as well as achieve 98.1% of capacitance retention after 5000 CV cycles. The PPy/CG/CNT ternary composite we have developed holds promise for high-efficiency supercapacitor applications. •PPy/CG/CNT ternary composite is synthesized by one-step electro-co-deposition.•CG provides more carboxyl as active sites for PPy polymerization compared with GO.•PPy/CG/CNT exhibits obviously boosted capacitive properties relative to PPy/GO/CNT.•PPy/CG/CNT shows high specific capacitance and excellent cycling stability.