The effect of oxygen containing species on the catalytic activity of ethanol oxidation for PtRuSn/C catalysts

Oxophilic Sn to Promote Glucose Oxidation to Formic Acid in Ni Nanoparticles

The electrochemical glucose oxidation reaction (GOR) presents an opportunity to produce hydrogen and high-value chemical products. Herein, we investigate the effect of Sn in Ni nanoparticles for the GOR to formic acid (FA). Electrochemical results show that the maximum activity is related to the amount of Ni, as Ni sites are responsible for catalyzing the GOR via the NiOOH/Ni(OH)2 pair. However, the GOR kinetics increases with the amount of Sn, associated with an enhancement of the OH- supply to the catalyst surface for Ni(OH)2 reoxidation to NiOOH. NiSn nanoparticles supported on carbon nanotubes (NiSn/CNT) exhibit excellent current densities and direct GOR via C-C cleavage mechanism, obtaining FA with a Faradaic efficiency (FE) of 93 % at 1.45 V vs. reversible hydrogen electrode. GOR selectivity is further studied by varying the applied potential, glucose concentration, reaction time, and temperature. FE toward FA production decreases due to formic overoxidation to carbonates at low glucose concentrations and high applied potentials, while acetic and lactic acids are obtained with high selectivity at high glucose concentrations and 55 °C. Density functional theory calculations show that the SnO2 facilitates the adsorption of glucose on the surface of Ni and promotes the formation of the catalytic active Ni3+ species.

The Ethanol Oxidation Reaction Performance of Carbon-Supported PtRuRh Nanorods

In this study, carbon-supported Pt-based catalysts, including PtRu, PtRh, and PtRuRh nanorods (NRs), were prepared by the formic acid reduction method for ethanol oxidation reaction (EOR) application. The aspect ratio of all experimental NRs is 4.6. The X-ray photoelectron spectroscopy and H2-temperature-programmed reduction results confirm that the ternary PtRuRh has oxygen-containing species (OCS), including PtOx, RuOx and RhOx, on its surface and shows high EOR current density at 0.6 V. The corresponding physical structure results indicate that the surface OCS can enhance the adsorption of ethanol through bi-functional mechanism and thereby promote the EOR activity. On the other hand, the chronoamperometry (CA) results imply that the ternary PtRuRh has the highest mass activity, specific activity, and stability among all catalysts. The aforementioned pieces of evidence reveal that the presence of OCS facilitates the oxidation of adsorbed intermediates, such as CO or CHx, which prevents the Pt active sites from poisoning and thus simultaneously improves the current density and durability of PtRuRh NRs in EOR.

On the Influence of Composition and Structure of Carbon-Supported Pt-SnO2 Hetero-Clusters onto Their Electrocatalytic Activity and Durability in PEMFC

A detailed study of the structure, morphology and electrochemical properties of Pt/C and Pt/x-SnO2/C catalysts synthesized using a polyol method has been provided. A series of catalysts supported on the SnO2-modified carbon was synthesized and studied by various methods including transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electrochemical methods, and fuel cell testing. The SnO2 content varies from 5 to 40 wt %. The TEM images, XRD and XPS analysis suggested the Pt-SnO2 hetero-clusters formation. The SnO2 content of ca. 10% ensures an optimal catalytic layer structure and morphology providing uniform distribution of Pt-SnO2 clusters over the carbon support surface. Pt/10wt %-SnO2/C catalyst demonstrates increased activity and durability toward the oxygen reduction reaction (ORR) in course of accelerated stress testing due to the high stability of SnO2 and its interaction with Pt. The polymer electrolyte membrane fuel cell current–voltage performance of the Pt/10wt %-SnO2/C is comparable with those of Pt/C, however, higher durability is expected.

Effect of the structural characteristics of binary Pt-Ru and ternary Pt-Ru-M fuel cell catalysts on the activity of ethanol electrooxidation in acid medium

In view of their possible use as anode materials in acid direct ethanol fuel cells, the electrocatalytic activity of Pt-Ru and Pt-Ru-M catalysts for ethanol oxidation has been investigated. This minireview examines the effects of the structural characteristics of Pt-Ru, such as the degree of alloying and Ru oxidation state, on the electrocatalytic activity for ethanol oxidation.