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The purpose of this work is activity evaluation of optimized Pd–Cu/rGO as an anode catalyst for electrooxidation of low ethanol concentrations (5–50 mM) in order to use in fuel cell-based breath alcohol analyzer. Accordingly, a simple and one-step synthesis of Pd/rGO and Pd–Cu/rGO with an optimized Pd/Cu ratio was performed via the chemical reduction method and evaluated for ethanol oxidation reaction (EOR). According to the transmission electron microscopy (TEM) and cyclic voltammetry (CV), the particle size and electrochemical active surface area (ECSA) of Pd0.9–Cu0.1/rGO were 4.5 nm and 181.5 m2 g−1, respectively. The ratio of If/Ib was measured to be 0.7 and 2.6 for Pd/rGO and Pd0.9–Cu0.1/rGO in the 0.5 M KOH solution containing 50 mM ethanol, thus indicating that the presence of Cu in the alloyed catalyst structure improved the catalytic activity by removing carbonaceous intermediates from the catalyst surface. Obtained results revealed that the onset potential (Eonset) of Pd0.9–Cu0.1/rGO was negatively shifted to 240 mV, as compared to Pd/rGO and no carbonate blockage of Pd–Cu/rGO sites happened in the presence of K2CO3. Therefore, Pd0.9–Cu0.1/rGO could be regarded as a superior anode catalyst for use in the anion exchange membrane fuel cell-based breath alcohol analyzer. [ABSTRACT FROM AUTHOR]

The oxygen reduction activity and methanol tolerance of Pt–Bi/C electrocatalysts were studied using electrochemical voltammetric techniques including rotating ring-disk electrode. The Pt–Bi/C catalyst was prepared via a polyol method and subjected to heat treatment to increase the degree of alloying. X-ray diffraction studies revealed the unalloyed character of the as-prepared catalyst and alloy formation upon heat treatment. The electrochemical behaviour of both catalysts showed different behaviour in dilute acid electrolytes, namely sulphuric and perchloric acids. In both electrolytes, the oxygen reduction reaction was found to occur via the four-electron process revealing that the mechanism of oxygen reduction is unaltered even in the presence of excess of methanol. Pt–Bi/C catalyst material showed dramatically different properties and reactivity with respect to oxygen reduction activity and methanol tolerance in perchloric and sulphuric acids. The onset potential for oxygen reduction reaction (ORR) significantly shifted by about 100 mV to more negative values and at the same time the current density was significantly enhanced. This type of non-ideal methanol-tolerant behaviour among Pt bimetallics and a “trade off” is common with all the known so-called methanol tolerant combinations of Pt. In general, the Pt–Bi surface appeared to have a negligibly lesser sensitivity towards methanol activity compared to pure platinum. [ABSTRACT FROM AUTHOR]

This study is concerned with the development of non-platinum electrocatalysts for the efficient 4-electron reduction of molecular oxygen to water in acidic media. A binary catalyst composed of electrodeposited manganese oxide nanoparticles (nano-MnO x ) and cobalt porphyrin macro complex (CoP) has been proposed in. The modification of glassy carbon (GC) electrode with CoP alone resulted in a significant positive shift of the oxygen reduction reaction (ORR) compared to the unmodified GC electrode while maintining a 2-electron reduction. That is a positive shift of the onset potential of the ORR of ca. 450 mV was achieved at the former electrode. The modification of the GC electrode with nano-MnO x alone did not affect the ORR peak potential, but caused a remarkable increase in the reduction peak current due to the catalytic disproportionation of the electrogenerated hydrogen peroxide into water and oxygen. The modification of a GC electrode with CoP and nano-MnO x (utilizing the advantages of the individual catalysts) resulted in the occurrence of the ORR at a significantly positive potential with almost double peak current compared to the unmodified GC electrode, suggesting a promising procedure for developing electrocatalysts for oxygen reduction in replacement of costly Pt. XPS and SEM techniques were employed to probe the structural and morphological characterization of the proposed binary catalysts. [ABSTRACT FROM AUTHOR]

Reductive annealing was chosen as a method for the syntheses of Se modified Ru/C catalysts. Initial preparation of a 20 wt% Ru/C was performed by impregnating RuCl3·2H2O on Vulcan XC72 with subsequent conditioning using H2 at 250 °C for 4 h. Surface treatment of Ru/C by SeO2 followed by reductive annealing produced Se modified Ru/C catalysts with a pre-determined Ru:Se = 1:0.15 and 1:1 a/o. Structural characterization was carried out using HRTEM while electrochemical characterization was performed using RDE measurements. It is concluded that the presence of Se on Ru has a positive effect on the oxygen reduction reaction of RuSe/C catalyst systems with an optimal loading of Se close to a Ru:Se ratio of 1:0.15 a/o. Overloading of selenium led to neutralization of its promoting effect. [ABSTRACT FROM AUTHOR]