Issue 39, 2019

Iodine doped composite with biomass carbon dots and reduced graphene oxide: a versatile bifunctional electrode for energy storage and oxygen reduction reaction

Abstract

We prepared carbon dots (CDs) via a sustainable, low-cost synthetic route employing eggplant biomass. A three-dimensionally porous composite consisting of eggplant-CDs and reduced graphene oxide (RGO) was first synthesized via one-pot hydrothermal process. The as-synthesized RGO/CD hybrid was further deoxygenated with HI acid to enhance ionic conductivity and introduce iodine dopants in the structure. The I-doped graphene/CD composite exhibited specific capacitances of 432 and 460 F g−1 at 2 mV s−1 and 1 A g−1 with excellent capacitance retention of 68.4% and 76.5%, as the scan rate and current density increased from 2 to 1000 mV s−1 and from 1 to 100 A g−1, respectively. Superior cycling stability of 94.6% capacitance retention over 10 000 cycles at 10 A g−1 was measured. As an electrocatalyst for oxygen reduction reaction (ORR) in 0.1 M KOH, the composite demonstrated an onset potential of 0.93 V vs. RHE and a kinetic limiting current density of 19.8 mA cm−2 at 0.1 V vs. RHE with an average electron transfer number of 3.57. The I-doped graphene/CD composite showed excellent ORR stability with current density retention of 97.7% under electrochemical stress (0.65 V vs. RHE) in comparison with 43.4% of the benchmark Pt/C under similar conditions. Thus, a sustainable process was developed to synthesize a multifunctional electrode based on agricultural wastes for energy storage and ORR.

Graphical abstract: Iodine doped composite with biomass carbon dots and reduced graphene oxide: a versatile bifunctional electrode for energy storage and oxygen reduction reaction

Supplementary files

Article information

Article type
Paper
Submitted
25 maj 2019
Accepted
20 sep 2019
First published
21 sep 2019

J. Mater. Chem. A, 2019,7, 22650-22662

Iodine doped composite with biomass carbon dots and reduced graphene oxide: a versatile bifunctional electrode for energy storage and oxygen reduction reaction

V. C. Hoang, K. N. Dinh and V. G. Gomes, J. Mater. Chem. A, 2019, 7, 22650 DOI: 10.1039/C9TA05559B

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