Effective NiMn Nanoparticles-Functionalized Carbon Felt as an Effective Anode for Direct Urea Fuel Cells.

Nasser Barakat,Mohannad Alajami,Saeed Al-Meer,Zafar Ghouri

doi:10.3390/nano8050338

Nasser Barakat, Mohannad Alajami + Show 2 more

Open Access

https://doi.org/10.3390/nano8050338

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Abstract

The internal resistances of fuel cells strongly affect the generated power. Basically, in the fuel cell, the anode can be prepared by deposition of a film from the functional electrocatalyst on a proper gas diffusion layer. Accordingly, an interfacial resistance for the electron transport is created between the two layers. Electrocatalyst-functionalized gas diffusion layer (GDL) can distinctly reduce the interfacial resistance between the catalyst layer and the GDL. In this study, NiMn nanoparticles-decorated carbon felt is introduced as functionalized GDL to be exploited as a ready-made anode in a direct urea fuel cell. The proposed treated GDL was prepared by calcination of nickel acetate/manganese acetate-loaded carbon felt under an argon atmosphere at 850 °C. The physiochemical characterizations confirmed complete reduction for the utilized precursors and deposition of pristine NiMn nanoparticles on the carbon felt fiber. In passive direct urea fuel cells, investigation the performance of the functionalized GDLs indicated that the composition of the metal nanoparticles has to be optimized as the GDL obtained from 40 wt % manganese acetate reveals the maximum generated power density; 36 mW/m2 at room temperature and 0.5 M urea solution. Moreover, the electrochemical measurements proved that low urea solution concentration is preferred as utilizing 0.5 M solution resulted into generating higher power compared to 1.0 and 2.0 M solution. Overall, this study opens a new avenue toward functionalization of the GDL as a novel strategy to overcome the interfacial resistance between the electrocatalyst and the GDL.

Highlights

Urea-contaminated water represents a big environmental challenge due to the inevitable treatment
Hydrogen can be obtained through electrochemical oxidation according to the following reactions [5,6,7]: Anode: CO(NH2)2 + 6OH− → N2 + 5H2O + CO2 + 6e−, E0 = −0.746 V
The electrochemical measurements of the assembled fuel cells indicated that the nanoparticles composition and urea solution concentration should be optimized to maximize the obtained power; 40 wt % Mn content and 0.5 M urea solution exhibit the highest power density

Summary

Introduction

Urea-contaminated water represents a big environmental challenge due to the inevitable treatment. Developing a suitable anode material to shift the process to be thermodynamically passable (i.e., positive cell potential) can lead to establish a direct urea fuel cell to generate power during electro-oxidation of the urea. Precious metals (e.g., Pt) are widely used as excellent performance anode materials for direct alcohol fuel cells, these metals show poor activity toward urea electro-oxidation [10]. If the electrocatalyst could be chemically deposited on the surface of the GDL to prepare a readymade anode without using a binder and filler, this can distinctly decreases the interfacial resistance that would result in enhancing the generated power. The carbon felt which have very good characteristics as GDL (excellent porosity, high electrical conductivity, distinguished chemical stability, and very acceptable mechanical properties) was decorated by NiMn nanoparticles and utilized as a ready made anode in a direct urea fuel cell. The electrochemical measurements of the assembled fuel cells indicated that the nanoparticles composition and urea solution concentration should be optimized to maximize the obtained power; 40 wt % Mn content and 0.5 M urea solution exhibit the highest power density

Preparation of the Functionalized GDL

Direct Urea Fuel Cell Structure

Characterizations

Results and Discussion