Facile labelling of graphene oxide for superior capacitive energy storage and fluorescence applications

Alex Yong Sheng Eng, Chun Kiang Chua, Martin Pumera

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

The majority of supercapacitor research studies on graphene materials today have been based upon developing electrochemical double-layer capacitors (EDLCs) using reduced graphenes. In contrast, graphene oxide (GO) is often neglected as a supercapacitor candidate due to its low electrical conductivity and surface area. Nonetheless, we present herein a fast (1 h) labelling of GO with o-phenylenediamine (PD) to produce PD-GO, exploiting inherent oxygen groups in creating new functionalities that exhibit capacitive enhancement from pseudo-capacitance. A high specific capacitance of 191 F g-1 was obtained (at 0.2 A g-1), comparable to recent binder-free graphene supercapacitors. The large surface-normalized capacitance of up to 628 μF cm-2 is also many times greater than the intrinsic capacitance of single-layer graphene (21 μF cm-2) as a result of additional pseudo-capacitance. A high capacity retention of ∼85% with each 10-fold increase in current density further indicates excellent rate performance. Hence, this approach in enhancing GO pseudo-capacitance may be similarly feasible as graphene EDLCs. Additionally, PD-GO was also found to exhibit a bright green fluorescence with a 540 nm maximum. The strongest fluorescence intensities arose from the smallest PD-GO fragments, and we attribute the origin to localised sp2 domains and newly formed phenazine edge groups. The dual enhancement of dissimilar properties such as capacitance and fluorescence emphasizes the continued significance of covalent functionalisation towards tuning of properties in graphene-type materials.

Original languageEnglish
Pages (from-to)9673-9681
Number of pages9
JournalPhysical Chemistry Chemical Physics
Volume18
Issue number14
DOIs
Publication statusPublished - 2016 Apr 14

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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