Effect of Sn Doping on Pd Electro-Catalysts for Enhanced Electro-Catalytic Activity towards Methanol and Ethanol Electro-Oxidation in Direct Alcohol Fuel Cells.

Cyril Tlou Selepe,Memory Zikhali,Nobanathi Wendy Maxakato,Ludwe Luther Sikeyi,Tebogo Abigail Mashola,Sandile Surprise Gwebu,Thabo Matthews

doi:10.3390/nano11102725

Cyril Tlou Selepe, Memory Zikhali + Show 5 more

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https://doi.org/10.3390/nano11102725

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Abstract

Carbon nano-onions (CNOs) were successfully synthesized by employing the flame pyrolysis (FP) method, using flaxseed oil as a carbon source. The alcohol reduction method was used to prepare Pd/CNOs and Pd-Sn/CNOs electro-catalysts, with ethylene glycol as the solvent and reduction agent. The metal-nanoparticles were supported on the CNO surface without adjusting the pH of the solution. High-resolution transmission electron microscopy (HRTEM) images reveal CNOs with concentric graphite ring morphology, and also PdSn nanoparticles supported on the CNOs. X-ray diffractometry (XRD) patterns confirm that CNOs are amorphous and show the characteristic diffraction peaks of Pd. There is a shifting of Pd diffraction peaks to lower angles upon the addition of Sn compared to Pd/CNOs. X-ray photoelectron spectroscopy (XPS) results also confirm the doping of Pd with Sn to form a PdSn alloy. Fourier transform infrared spectroscopy (FTIR) displays oxygen, hydroxyl, carboxyl, and carbonyl, which facilitates the dispersion of Pd and Sn nanoparticles. Raman spectrum displays two prominent peaks of carbonaceous materials which correspond to the D and G bands. The Pd-Sn/CNOs electro-catalyst demonstrates improved electro-oxidation of methanol and ethanol performance compared to Pd/CNOs and commercial Pd/C electro-catalysts under alkaline conditions.

Highlights

With the growing energy crisis and environmental pollution over the last few decades, fuel cell technology has gained more attention [1]
Fuel cells are classed based on the type of electrolyte they utilize, which determines the operating temperature and catalyst that is appropriate for those conditions
This study aimed to develop catalyst support material for the enhancement of catalytic activity and stability of the electro-catalyst for alcohol oxidation reactions (AOR) in alkaline media

Summary

Introduction

With the growing energy crisis and environmental pollution over the last few decades, fuel cell technology has gained more attention [1]. Fuel cells exhibit high efficiency of energy conversion and their electro-catalytic reactions produce minimal pollution relative to the polluting nature of combustion engines. Among various types of fuel cells, direct alcohol fuel cells (DAFCs) are the most attractive because they use liquid and renewable alcohol as fuel. They are recognized as green energy producers capable of transforming renewable sources into power by feeding liquid fuels straight to the anode [3]

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