Methanol is so far the most commonly considered fuel as an alternative to hydrogen. However, the practical performance is limited by several factors, which include the slow kinetics of methanol oxidation and crossover of methanol from the anode to the cathode side of the cell. More recently, there has been growing interest in dimethyl ether (CH₃OCH₃), a gas commonly used in aerosol propellants, solvents and coolants, as a possible alternative fuel for low temperature fuel cells. Dimethyl ether (DME) is non-toxic, non-teratogenic, non-mutagenic and non-carcinogenic gas. When oxidized to CO₂, a CH₃OCH₃ molecule releases 12 electrons. The fuel has several advantages over typical organic fuels. Unlike ethanol (CH₃CH₂OH), the CH₃OCH₃ ether does not require breaking of the C-C bond. A fairly low CH₃OCH₃ dipole moment results in the lower ether crossover (through the membrane) in comparison to methanol. Dimethyl ether is much less toxic than methanol and can be readily stored and transported using existing technologies. In addition, the CH₃OCH₃ ether has potentially higher energy density relative to methanol (namely, 8.2 vs. 6.1 kWh kg^-1).

Platinum is one of the typical catalysts for the oxidation of organic molecules. It is quite active toward the dehydrogenation step, but suffers from the CO oxidation step. The bimetalic catalysts (e.g. PtRu, PtSn) can lower the onset potential of DME oxidation peak from 0.5 V for Pt/C to 0.4 V vs. Normal Hydrogen Electrode (NHE), but the maximum current densities are obtained on Pt/C.

We propose here to study the electrooxidation of DME at Pt and PtRu nanoparticles that have been deposited onto nanostructured zirconium(IV) oxide matrix (thin film on electrode surface). Zirconia is known to act as a catalytic component capable of enhancing the reactivity of the electrocatalytic system by increasing the overall acidity at the reaction interface. When combined (as a support) with Pt or PtRu centers, the existence of large population of hydroxyl groups on ZrO₂ surface is believed to facilitate desorption of CO adsorbates from Pt and to induce their oxidation to CO₂. In the presence of nanostructured zirconia (existing in the vicinity of the catalytic metal), the transport of protons at the electrocatalytic interface is also favored. Synergistic interactions between ruthenium and zirconia components are also feasible. In the present report, we will not limit our results to DME, but similar effects have been observed during oxidation of methanol. We are also going to consider combination of Pt or PtRu with the other metal (Pd) or metal (W, Mo) oxo nanostructures.    

The support from National Research Center (NCN), Poland under the MAESTRO Project No 2012/04/A/ST4/00287 is highly appreciated.