Enhancement of oxidation of dimethyl ether through application of zirconia matrix for immobilization of noble metal catalytic nanoparticles

Abstract

Electrocatalytic activity of Pt and bimetallic PtRu nanoparticles (both Vulcan supported and unsupported) toward electrooxidation of dimethyl ether (DME), a potential small organic molecule fuel, in an acid medium (0.5 mol dm−3 H2SO4) has been significantly enhanced by dispersing them over a thin film of zirconia (ZrO2). The enhancement effects concern increases of the DME electrocatalytic current densities recorded under both cyclic voltammetric and chronoamperometric conditions. Similar effects have been observed for the oxidation of methanol. Regarding the dissimilar DME electrooxidation mechanisms at Pt and PtRu catalytic centers, the activating capabilities of zirconia seem to originate from the high population of reactive –OH groups favoring mobility of protons and the capability of inducing the oxidative removal of poisoning (CO-type) intermediates both at platinum and ruthenium catalytic sites. In the presence of the zirconia matrix, the onset potential for the oxidation of DME (particularly at PtRu) is shifted more than 50 mV toward less positive potentials. Mutual metal-support interactions are also postulated.

Enhancement of Oxidation of Dimethyl Ether Through Utilization of SnO2 for Immobilization of Pt Catalytic Nanoparticles

“…Pt-(CO)ads + OH -→ Pt + CO2 + H2O + e - (11) However, the excessive increase of SnO2 leads to a decrease in catalyst performance, because the decrease of the carrier conductivity and the obstruction of the active sites on the Pt surface, which obstructs the further dimethyl ether electrooxidation and gives rise to the current density decay on it [46].…”

Hybrid Electrocatalysts Composed of PtSn, Ru or PtRu Nanoparticles for Low-Temperature Oxidation of Dimethyl Ether Fuel

“…3, dashed line). No oxidation current has been observed above 0.8 V, where the PtRu surface becomes gradually covered with oxides and, therefore, is becoming less active during the DME oxidation (13,17,(42)(43)(44)(45). The net oxidation current of DME equals about 55 μA cm -2 at potential 0.62 V, and the starting potential for electooxidation of DME is 0.38 V. Careful examination of the oxidation of DME in 0.5 mol dm -3 H2SO4 at PtRu nanoparticles (Fig.…”

“…The main constraints related to application of common Pt-based catalysts (e.g. Pt and bimetallic PtRu, PtSn) (10)(11)(12)(13)(14)(15)(16)(17) in direct DME fuel cells concern the system's low practical electrooxidation efficiency.…”

“…Theoretical analyses suggest that alloy formation that alters the electronic structure of Pt can alter COads and OH − ads bonding to the catalyst surface while minimizing surface dilution of the active Pt sites (19). In comparison to simple Pt, the catalytic activity of bimetallic systems, PtRu and PtSn, have lower onset potentials for the DME electrooxidation (20,21), particularly, when the Vulcan supported catalytic nanoparticles have been considered (13,17,22).…”

Enhancement of Activity of Copper Sites Toward Electroreduction of Carbon Dioxide through Hierarchical Deposition of Metal Oxide Cocatalysts

“…But in many electrocatalytic applications., there is a need to improve charge distribution and to assure better utilization of metallic (e.g. Pt) sites dispersed over the semiconducting ZrO2 matrices (37,(43)(44)(45)(46)(47).…”