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Poly(3,4-ethylenedioxythiophene)-(PEDOT)-functionalized reduced graphene oxide (rGO) with MnO2 nanoparticles (MnO2/PEDOT/rGO) was prepared using electrochemical methods. The MnO2/PEDOT/rGO was obtained through the electrochemical reduction of PEDOT/GO and under electrochemical treatment in KMnO4. The PEDOT/rGO and MnO2/PEDOT/rGO were characterized by several instrumental and electrochemical methods. The electrocatalytic O2 reduction for both electrodes was investigated via cyclic and hydrodynamic voltammetry in 0.1 M KOH aqueous solutions. The kinetic analysis in comparison to PEDOT/rGO a significant enhancement was found for the MnO2/PEDOT/rGO. The proposed main path in the oxygen reduction reaction (ORR) mechanism on the MnO2/PEDOT/rGO was the direct four-electron transfer process with faster transfer kinetic rate. The better ORR kinetics were obtained due to the excellent composite formation and well attachment of MnO2 NPs within oxide form. The PEDOT/rGO was less stable for long term use than MnO2/PEDOT/rGO. Copyright © 2015 American Scientific Publishers All rights reserved.

Poly(3,4-ethylenedioxythiophene) functionalized graphene with palladium nanoparticles (denoted as Pd/PEDOT/rGO) has been synthesized for electrochemical oxygen reduction reaction (ORR) in alkaline solution. The structural features of catalyst are characterized by scanning electron microscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The TEM images suggest a well dispersed PdNPs onto PEDOT/rGO film. The ORR activity of Pd/PEDOT/rGO has been investigated via cyclic voltammetry (CV), rotating disk electrode (RDE) and rotating ring disk electrode (RRDE) techniques in 0.1 M KOH aqueous solution. Comparative CV analysis suggests a general approach of intermolecular charge-transfer in between graphene sheet and PdNPs via PEDOT which leads to the better PdNPs dispersion and subsequently superior ORR kinetics. The results from ORR measurements show that Pd/PEDOT/rGO has remarkable electrocatalytic activity and stability compared to Pd/rGO and state-of-the-art Pt/C. The Koutecky–Levich and Tafel analysis suggest that the proposed main path in the ORR mechanism has direct four-electron transfer process with faster transfer kinetic rate on the Pd/PEDOT/rGO.

Orange II, an azo dye, is sometimes illegally used as a red dye in food products despite its adverse health effects if consumed. Therefore, the determination of low concentrations of Orange II is an important target. An Orange II sensor was prepared using electrochemically reduced graphene oxide grafted with 5-amino-1,3,4-thiadiazole-2-thiol-Pt nanoparticles (denoted as ERGO-ATDT-Pt) onto a glassy carbon electrode (GCE) and investigated for Orange II detection in 0.1 M acetate buffer solution (ABS at pH 4.5) with prominent reversible redox peaks. A wide linear range of 1 × 10- 8-6 × 10-7 M with a low detection limit of 3.4 × 10-10 M (s/n = 3) was found for Orange II detection. This developed ERGO-ATDT-Pt/GCE sensor showed good selectivity, excellent stability and better response to the real sample analysis with excellent recovery. © 2014 Elsevier Ltd. All rights reserved.

We have been prepared a series of heteroatoms (N and/or S) doped graphene in different ratios from various doping precursors (pyridine, thiophene and bithiophene combined separately with dipyrrolemethane and used as single N and/or S precursor) by thermal reaction. The as synthesized heteroatoms-doped graphene materials have also been characterized via transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The XPS and Raman investigations suggest a better dual-doping with higher conversion rate of graphitic-N and thermal reduction of oxygen into the graphene sheets. The electrochemical investigation reveals that the both N and S-doped graphene (S1N2-GN800 and S2N2-GN800) have better catalytic activity on oxygen reduction reaction (ORR) than only N-doped graphene (N3-GN800) with the assistance of synergistic effect of dual-doping. Particularly, the high thermal treated final product, N and S dual-doped graphene (S2N2-GN1000) shows remarkable electrocatalytic activity towards the ORR which not only establishes a pathway of four-electron transfer reaction but also exhibits a better fuel selectivity and stability than that of commercially available 20wt% Pt/C electrode. © 2014 Elsevier B.V. All rights reserved., National Research Foundation of Korea Ministry of Education, Science and Technology: 2010-0007864, This research has supported by the Basic Science Research Program through a National Research Foundation of Korea (NRF) grant funded by the Ministry of Education, Science, and Technology ( 2010-0007864 ). Appendix A