Palladium-Nickel Electrocatalysts on Nitrogen-Doped Reduced Graphene Oxide Nanosheets for Direct Hydrazine/Hydrogen Peroxide Fuel Cells

Mir Ghasem Hosseini,Sigrid Wolf,Vahid Daneshvari-Esfahlan,Viktor Hacker,Hossein Aghajani

doi:10.3390/catal11111372

Abstract

In the present work, nitrogen-doped reduced graphene oxide-supported (NrGO) bimetallic Pd–Ni nanoparticles (NPs), fabricated by means of the electrochemical reduction method, are investigated as an anode electrocatalyst in direct hydrazine–hydrogen peroxide fuel cells (DHzHPFCs). The surface and structural characterization of the synthesized catalyst affirm the uniform deposition of NPs on the distorted NrGO. The electrochemical studies indicate that the hydrazine oxidation current density on Pd–Ni/NrGO is 1.81 times higher than that of Pd/NrGO. The onset potential of hydrazine oxidation on the bimetallic catalyst is also slightly more negative, i.e., the catalyst activity and stability are improved by Ni incorporation into the Pd network. Moreover, the Pd–Ni/NrGO catalyst has a large electrochemical surface area, a low activation energy value and a low resistance of charge transfer. Finally, a systematic investigation of DHzHPFC with Pd–Ni/NrGO as an anode and Pt/C as a cathode is performed; the open circuit voltage of 1.80 V and a supreme power density of 216.71 mW cm−2 is obtained for the synthesized catalyst at 60 °C. These results show that the Pd–Ni/NrGO nanocatalyst has great potential to serve as an effective and stable catalyst with low Pd content for application in DHzHPFCs.

Highlights

Direct hydrazine–hydrogen peroxide fuel cells (DHzHPFCs) are known as unique power sources for air-independent applications in space and underwater
N2H4 is considered a promising liquid fuel for the following reasons: (1) its handling is safer; (2) its electrooxidation occurs without the generation of carbon dioxide, which leads to a reduction of greenhouse gas emissions; (3) catalysts are not poisoned during the N2H4 oxidation reaction due to lack of the carbonaceous intermediates production, as reported by Mohammed et al, who investigated the sensitive electrochemical detection of hydrazine based on SnO2/CeO2 nanostructured oxide and reported the high stability, sensitivity and repeatability of hydrazine oxidation on the synthesized nanomaterial [6]; and (4) because of the high theoretical electromotive force of 1.56 V [7] and power density (PD) of 5.4 KWh L−1 observed for DHzHPFCs
The electrochemical properties of the Pd–Ni/nitrogen-doped reduced graphene oxide-supported (NrGO) and Pd/NrGO catalysts were investigated by employing Cyclic voltammetry (CV), CA, CP, and electrochemical impedance spectroscopy (EIS) techniques, and the results proved that Pd– Ni/NrGO has a higher catalytic activity and a longer lifetime in comparison with Pd/NrGO

Summary

Introduction

Direct hydrazine–hydrogen peroxide fuel cells (DHzHPFCs) are known as unique power sources for air-independent applications in space and underwater. The use of hydrazine (N2H4) as a high-energy fuel in FCs has been investigated since the 1970s [1,2], as an alternative fuel in portable power sources [3,4,5]. N2H4 is considered a promising liquid fuel for the following reasons: (1) its handling is safer; (2) its electrooxidation occurs without the generation of carbon dioxide, which leads to a reduction of greenhouse gas emissions; (3) catalysts are not poisoned during the N2H4 oxidation reaction due to lack of the carbonaceous intermediates production, as reported by Mohammed et al, who investigated the sensitive electrochemical detection of hydrazine based on SnO2/CeO2 nanostructured oxide and reported the high stability, sensitivity and repeatability of hydrazine oxidation on the synthesized nanomaterial [6]; and (4) because of the high theoretical electromotive force of 1.56 V [7] and power density (PD) of 5.4 KWh L−1 observed for DHzHPFCs. On the other hand, a simple internal structure of fuel cells is obtained with an oxidant of hydrogen peroxide (H2O2) [8,9,10].

Methods

Results

Conclusion