Elsevier

Electrochimica Acta

Volume 107, 30 September 2013, Pages 194-199
Electrochimica Acta

Three-dimensional porous Ni film electrodeposited on Ni foam: High performance and low-cost catalytic electrode for H2O2 electrooxidation in KOH solution

https://doi.org/10.1016/j.electacta.2013.05.152Get rights and content

Highlights

  • A 3D porous Ni film is electrodeposited on Ni foam via electrodeposition.

  • Ni/Ni-foam electrode shows high catalytic activity for H2O2 electrooxidation.

  • DPPFC with Ni/Ni foam anode and Pd/CFC cathode has been demonstrated.

Abstract

A novel three-dimensional carbon- and binder-free porous Ni electrode is successfully prepared by electrodeposition of Ni microparticle assembly on Ni foam substrate using hydrogen bubbles as the template. Scanning electron microscopy and X-ray diffraction analyses are performed to characterize the morphology and structure. Electrochemical methods including cyclic voltammetry and chronoamperometry are used to examine the catalytic performance of electrode for H2O2 electrooxidation in KOH solution. Results reveal that the electrode exhibited high catalytic activity and good stability in the strong oxidizing and corrosive solution of H2O2 and KOH. The catalytic mechanism of H2O2 electrooxidation on the Ni electrode is discussed and Ni(OH)2 is believed to be the catalytic active species. The apparent activation energy of H2O2 electrooxidation on the Ni catalyst is found to be 21.2 kJ mol−1. A direct peroxide–peroxide fuel cell using the Ni/Ni-foam as the anode achieves a peak power density of 19.4 mW cm−2, higher than that reported in literatures. The electrode shows great promise as the anode of direct peroxide–peroxide fuel cell due to its low cost, high activity and stability.

Introduction

Hydrogen peroxide (H2O2) can be used as both a carbon-free energy carrier and a strong oxidant in a novel fuel cell, namely direct peroxide–peroxide fuel cell (DPPFC) [1], [2], [3], [4], [5], [6], [7], [8], [9]. DPPFC exhibits several advantages comparing to other types of liquid-feed direct fuel cells (e.g., direct methanol fuel cell, direct borohydride fuel cell, direct formic acid fuel cell) [10], [11], [12], [13], [14], [15], [16], [17], such as, low cost, compact, easy operation, workable without air, and providing both power and oxygen. So it is a very promising underwater and space power source. Besides, both the anode and the cathode reactions have fast kinetics and involve no poisoning species, which allows the use of non-Pt electrocatalysts.

H2O2 as the fuel of DPPFC is electrooxidated in H2O2-containing KOH solution at the anode catalyst [3], [4], [5], [6], [7], [8] (Eq. (1)).HO2 + OH  O2 + H2O + 2e E0 = 0.146 V

Clearly, the anode works in a strong oxidizing alkaline solution, which requires that the anode must be stable in such a harsh environment. In general, carbon-supported powder electrocatalysts are commonly used in fuel cells. The electrodes using these powder electrocatalysts were usually fabricated by binding the powder electrocatalysts onto carbon paper using organic polymer binders. However, carbon can be slowly oxidized and binders can be gradually degraded in the harsh H2O2 + KOH solution, which will lead to deactivation of electrodes. Therefore, the conventional fuel cell electrodes cannot sustain the working environment of DPPFC. On the other hand, since O2 was continuously produced at the anode of DPPFC, the anode should have a porous structure to allow O2 quickly diffusing away from the electrode to regenerate the catalytic active sites.

Recently, Ni foam has been studied as the anode in a direct borohydride fuel cell due to its three-dimensional (3D) open porous structure and good stability in alkaline electrolyte [18]. However, its low number of active sites limited its catalytic performance even though it shows good mass transport property. Carbon supported nickel has been investigated as the anode electrocatalyst of DPPFCs because of its low-cost and no catalysis to H2O2 decomposition [3]. In this study, we reported a Ni foam supported Ni particle electrode (Ni/Ni-foam) for H2O2 electrooxidation in KOH solution. The electrode was prepared by simple electrodeposition of Ni particles onto Ni foam using hydrogen bubble as the template [19], [20], [21], [22], [23], [24], [25]. In this way, a 3D porous all-metal electrode having larger surface area, excellent mass transport property and long term stability was obtained.

Section snippets

Experimental

The Ni/Ni-foam electrode was prepared by electro-depositing a porous Ni film on Ni foam using hydrogen bubble as template (Scheme 1). The deposition was performed in a three-electrode electrochemical cell with nickel foam working electrode, platinum foil counter electrodes and saturated Ag/AgCl (3 mol L−1 KCl) reference electrode using 2.0 mol L−1 NH4Cl and 0.1 mol L−1 NiCl2 as the deposition solution. The electrode was obtained by applying a constant current of −2.0 A cm−2 (−3.0 V ± 0.2 V) for 100 s via a

Characterization of the Ni/Ni-foam electrode

The 3D porous nano-Ni film is successfully prepared by a facile cathodic electrodeposition accompanying hydrogen evolution template. The Ni film exhibited a 3D porous structure consisting of interconnected micro-particles which attached on the entire surface of Ni foam substrate (Fig. 2A–C). The Ni/Ni-foam electrode has a larger surface area than Ni foam substrate. The Ni particle surfaces are easy accessible to H2O2 and electrolytes due to the existence of voids among particles, which enable a

Conclusions

A novel carbon-free all-metal nickel anode for DPPFC has been successfully prepared by forming a porous 3D Ni microstructure on Ni foam via a simple electrochemical method. The electrode demonstrated higher catalytic activity toward H2O2 electrooxidation than the state-of-the-art Pd/CFC electrode and exhibited excellent stability in harsh alkaline electrolyte. The DPPFC with the Ni/Ni-foam anode displayed a peak power density of 19.4 mW cm−2 at 20 °C. The high catalytic performance and the low

Acknowledgements

We gratefully acknowledge the financial support of this research by National Nature Science Foundation of China and Harbin Science and Technology Innovation Fund for Excellent Academic Leaders (2012RFXXG103).

References (33)

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