Stable N-doped & FeNi-decorated graphene non-precious electrocatalyst for Oxygen Reduction Reaction in Acid Medium

Nasser A M Barakat,Zafar Khan Ghouri,Saeed Al-Meer,Ahmed G El-Deen

doi:10.1038/s41598-018-22114-1

Nasser A M Barakat, Zafar Khan Ghouri + Show 2 more

Open Access

https://doi.org/10.1038/s41598-018-22114-1

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Abstract

NiFe nanoparticles-decorated & N-doped graphene is introduced as an effective and stable non-precious electrocatalyst for ORR in the acid medium. Compared to conventional Pt/C electrodes under the same conditions, the proposed nanocatalyst shows closer onset potential and current density. Typically, the observed onset potentials and current densities for the synthesized and Pt/C electrodes are 825 and 910 mV (vs. NHE) and −3.65 and −4.31 mA.cm−2 (at 5 mV.s−1), respectively. However, the most important advantage of the introduced metallic alloy-decorated graphene is its distinct stability in acid medium; the retention in the electrocatalytic performance after 1,000 successive cycles is approximately 98%. This finding is attributed to the high corrosion resistance of the NiFe alloy. The kinetic study indicates that the number of the transferred electrons is 3.46 and 3.89 for the introduced and Pt/C (20 wt%) electrodes, respectively which concludes a high activity for the proposed nanocomposite. The suggested decorated graphene can be synthesized using a multi-thermal method. Typically, nickel acetate, iron acetate, graphene oxide and urea are subjected to MW heating. Then, sintering with melamine in an Argon atmosphere at 750 °C is required to produce the final electrocatalyst. Overall, the introduced NiFe@ N-doped Gr nanocomposite shows remarkable electrochemical activity in the acid medium with long-term stability.

Highlights

The confirmed near depletion of fossil oils is forcing the researchers to find effective, low cost, and environmentally safe energy devices
Due to the reduction process, the reduced graphene oxide shows a broad peak that can be fitted using a Lorentzian function into three peaks, which are centered at 2θ = 20.17°, 23,78° and 25.88°, which correspond to the interlayer distances of 4.47, 3.82 and 3.53 Å, respectively
Graphene sheets were decorated with FeNi nanoparticles by hydrothermal treatment of graphene oxide in the presence of nickel acetate and iron acetate

Summary

Introduction

The confirmed near depletion of fossil oils is forcing the researchers to find effective, low cost, and environmentally safe energy devices. In addition to this dilemma, the serious negative impact to the climate promotes the elimination of the fossil fuels utilization. Considering that the most effective non-precious ORR catalysts are primarily nitrogen-doped nanocarbons (e.g. N-doped carbon nanotubes (CNT)[11] and CNT/graphene mixture12), supporting of effective bimetallic nanoparticles on a proper N-doped carbonaceous material can distinctly enhance the ORR electrocatalytic activity[13]. Besides enhancing the electrocatalytic activity, N-doped carbon nanostructural supports showed more stability than nitrogen-free ones due to the high number of surface nucleation sites, which allows for anchorage and high dispersion of the catalyst nanoparticles on surface of the support material[14,15,16]. Compared to other carbon nanostructures, the chemical route for graphene synthesis provides a good chance for functionalization by active groups which aids in decoration surface by metallic nanoparticles[9]

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