Acta Phys. -Chim. Sin. ›› 2014, Vol. 30 ›› Issue (2): 297-304.doi: 10.3866/PKU.WHXB201312233

• ELECTROCHEMISTRY AND NEW ENERGY • Previous Articles     Next Articles

Influence of Graphene with Different Oxidation Degrees on Nickel Hydroxide Pseudocapacitor Characterization

HE Yuan-Yuan, ZHANG Jin-Jiang, ZHAO Jian-Wei   

  1. State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210008, P. R. China
  • Received:2013-10-21 Revised:2013-12-23 Published:2014-01-23
  • Contact: ZHAO Jian-Wei E-mail:zhaojw@nju.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (51071084, 21273113, 21121091, 11204120) and National Key Technology R&DProgramof China (2012BAF03B05).

Abstract:

We designed a series of models of reduced graphene oxide sheets (rGNOs) with different oxidation degrees and then studied the interactions between oxidation defects on rGNOs and nickel hydroxide (Ni(OH)2) using density functional theory (DFT). The adsorption energy between the oxygen-containing groups on rGNOs and Ni(OH)2 is dependent on the oxidation degree of rGNOs. The variations of atomic distances and charge distribution of the oxide-defected graphene after absorbing Ni(OH)2 suggested that the oxygen-containing groups on rGNOs improve the characteristics of Ni(OH)2 as a pseudocapacitor. These theoretical results agree well with available experimental observations and give an explanation for some experimental results. We also introduce a simple potentiostatic electrodeposition method, with which Ni(OH)2 nanoparticles about 5 nm in diameter were effectively dispersed on the substrate via induction of oxidation defects on rGNOs. In the fabrication of Ni(OH)2/rGNOs, electrochemical reduction of graphene oxide is the key process. The stronger adsorption results in Ni(OH)2/rGNOs have higher rate pseudocapacitance (1591 F·g-1 at 5 mV·s-1) compared with that of Ni(OH)2 on bare nickel (656 F·g-1 at 5 mV·s-1). The variations of the geometries and charge distributions of the rGNOs after absorbing Ni(OH)2 lead to the lower equivalent series resistance and better frequency response of Ni(OH)2/rGNOs than Ni(OH)2/Ni. The high capacitance of Ni(OH)2/rGNOs indicates that Ni(OH)2/rGNOs have the potential of being used as the electrode material of pseudocapacitors.

Key words: Nickel hydroxide, Oxidation defect, Atomic distance, Charge distribution, Adsorption energy, Pseudocapacitance

MSC2000: 

  • O646