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Nitrogen-doped reduced graphene oxide-polyaniline composite materials: hydrothermal treatment, characterisation and supercapacitive properties
New Journal of Chemistry, Volume: 47, Issue: 7, Pages: 3502 - 3515
Swansea University Author: Matthew Davies
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Among other factors, the electrochemical capacitor (EC) properties of graphene oxide (GO) are limited by conductivity issues emanating from high oxygen concentrations. Hence, innovative GO modifications, such as derivatisation and synthesising composites with conducting polymers, are required to boo...
|Published in:||New Journal of Chemistry|
Royal Society of Chemistry (RSC)
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Among other factors, the electrochemical capacitor (EC) properties of graphene oxide (GO) are limited by conductivity issues emanating from high oxygen concentrations. Hence, innovative GO modifications, such as derivatisation and synthesising composites with conducting polymers, are required to boost the EC properties. This allows the exploitation of the low material cost associated with carbonaceous materials. Herein, the effect of temperature (70, 130 and 190 °C) on the hydrothermal treatment of a GO/urea mixture (to form nitrogen-doped reduced GO samples U70, U130 and U190 (N-RGO), respectively) was investigated in order to study the resulting physicochemical and EC properties of N-RGO in a K2SO4 electrolyte. Subsequently, the EC properties of the N-RGO obtained from the optimum temperature were investigated in composites with polyaniline (PANI). The functionality of the composites in the electrolytes, namely, K2SO4 (SO42− radius: 258 pm) versus KOH (OH− radius: 133 pm), was compared. The nitrogen at% in GO and N-RGO (U190) was 0.39 and 6.74%, respectively, with corresponding conductivities of 4.61 × 10−7 and 4.17 × 10−1 S cm−1. Compared with GO, U130 achieved the highest increase in specific capacitance (Cs) of 200 times at 10 mV s−1. The 5 wt% PANI composite displayed the highest enhancement of Cs of 14 032% at 50 mV s−1 and 4749% at 5 mV s−1 relative to N-RGO and PANI in K2SO4, respectively. The highest Cs values for NRGO-PANI composites in KOH were more than double those of K2SO4. This work demonstrates that the hydrothermal treatment temperature tailors the physicochemical properties of the doped GO and, together with the anion size of the electrolyte and PANI wt%, synergistically tunes the EC properties of the ultimate PANI-N-RGO composite.
Faculty of Science and Engineering
This work is based on the research supported mainly by funding through the EPSRC GCRF SUNRISE project (grant number: EP/P032591/1) and partly by the National Research Foundation (NRF) of South Africa. MLD is grateful for the financial support of the EPSRC (EP/S001336/1) and the funding of the SPECIFIC Innovation and Knowledge Centre by the EPSRC [EP/N020863/1], Innovate UK , and the European Regional Development Fund [c80892] through the Welsh Government. The authors wish to thank the University of KwaZulu-Natal (UKZN) and the UKZN Nanotechnology Platform forsupportingthisworkbyproviding the necessary research infrastructure. The authors are also grateful to James Mcgettrick for assistance in X-ray photoelectron spectroscopy analysis.