Enhancement of Ethanol Oxidation Reaction on Pt (PtSn)-Activated Nickel Foam Through In situ Formation of Nickel Oxy-Hydroxide Layer

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

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.

Recent Developments for the Application of 3D Structured Material Nickel Foam and Graphene Foam in Direct Liquid Fuel Cells and Electrolyzers

Platinum and platinum-based catalysts are some of the most effective catalysts used in fuel cells. However, electrocatalysts used for direct liquid fuel cells (DLFCs) and electrolyzers are high cost and suffer from several other problems, thus hindering their commercialization as power sources to produce clean energy. Common issues in electrocatalysts are low stability and durability, slow kinetics, catalyst poisoning, high catalyst loading, high cost of the catalytic materials, poisoning of the electrocatalysts, and formation of intermediate products during electrochemical reactions. The use of catalyst supports can enhance the catalytic activity and stability of the power sources. Thus, nickel foam and graphene foam with 3D structures have advantages over other catalyst supports. This paper presents the application of nickel foam and graphene foam as catalyst supports that enhance the activities, selectivity, efficiency, specific surface area, and exposure of the active sites of DLFCs. Selected recent studies on the use of foam in electrolyzers are also presented.

The fabrication composite material of bimetallic micro/nanostructured palladium–platinum alloy and graphene on nickel foam for the enhancement of electrocatalytic activity

A composite of micro/nanostructured palladium–platinum alloy, reduced graphene oxide and polydopamine on nickel foam was obtained by a chemical immersion method and anneal method with high catalytic efficiency for the ethanol oxidation.

Galvanic replacement of liquid metal galinstan with Pt for the synthesis of electrocatalytically active nanomaterials

The galvanic replacement reaction is a verstile method for the fabrication of bimetallic nanomaterials which is usually limited to solid precursors. Here we report on the galvanic replacement of liquid metal galinstan with Pt which predominantly results in the formation of a Pt5Ga1 material. During the galvanic replacement process an interesting phenomenon was observed whereby a plume of nanomaterial is ejected upwards from the centre of the liquid metal droplet into solution which is due to surface tension gradients on the liquid metal surface that induces surface convection. It was also found that hydrogen gas was liberated during the process facilitated by the formation of the Pt rich nanomaterial which is a highly effective catalyst for the hydrogen evolution reaction (HER). The material was characterised by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction and dynamic light scattering measurements. It was found that Pt5Ga1 was highly effective for the electrochemical oxidation of methanol and ethanol and outperformed a commercial Pt/C catalyst. Density functional theory calculations confirmed that the increased activity is due to the anti poisoning properties of the surface towards CO upon the incorporation of Ga atoms into a Pt catalyst. The use of liquid metals and galvanic replacement offers a simple approach to fabricating Ga based alloy nanomaterials that may have use in many other types of applications.

Electrooxidation of phenol on carbon fibre-based anodes through continuous electrolysis of synthetic wastewater

This work reports on the process of phenol electrooxidation, which is carried-out through continuous electrolysis of synthetic, sodium sulphate-based wastewater. Phenol electrodegradation is examined by means of a laboratory size (ca. 700 cm3 of working volume), poly (methyl methacrylate)-made electrolyser unit for various, carbon fibre and graphite-based anode configurations, and stainless steel cathodes, two different current-densities and concentrations of phenol in synthetically prepared wastewater solution. Proper monitoring of phenol degradation (including quantitative identification of reaction products and calculation of specific energy consumption) in wastewater is performed by means of instrumental, combined HPLC and MS technique in function of electrolysis time.