Harnessing dimethyl ether and methyl formate fuels for direct electrochemical energy conversion

In this work, the oxidation of a mixture of dimethyl ether (DME) and methyl formate (MF) was studied in both an aqueous electrochemical cell and a vapor-fed polymer electrolyte membrane fuel cell (PEMFC) utilizing a multi-metallic alloy catalyst, Pt3Pd3Sn2/C, discovered earlier by us. The current obtained during the bulk oxidation of a DME-saturated 1 M MF was higher than the summation of the currents provided by the two fuels separately, suggesting the cooperative effect of mixing these fuels. A significant increase in the anodic charge was realized during oxidative stripping of a pre-adsorbed DME+MF mixture as compared to DME or MF individually. This is ascribed to greater utilization of specific catalytic sites leading to lower energy of the dual-fuel than of the sum of the individual molecules as confirmed by the density functional theory (DFT) calculations. Fuel cell polarization was also conducted using a Pt3Pd3Sn2/C (anode) and Pt/C (cathode) catalysts-coated membrane (CCM). The enhanced surface coverage and active site utilization resulted in providing a higher peak power density by the DME+MF mixture-fed fuel cell (123 mW cm−2 at 0. 45 V) than with DME (84 mW cm−2 at 0.35 V) or MF (28 mW cm−2 at 0.2 V) at the same total anode hydrocarbon flow rate, temperature under ambient pressure

Ruthenium Phosphide Synthesis and Electroactivity toward Oxygen Reduction in Acid Solutions

Ruthenium phosphides are known to be highly stable and conductive materials. A new process was developed to prepare ruthenium phosphide catalysts for oxygen reduction in acid solutions. Several synthesis methods have been applied to form pure RuP and Ru₂P as well as mixed phases of Ru and Ru_<i>x</i>P (<i>x</i> ≥ 1). These methods utilize high-temperature solid-state synthesis and reaction under autogenic pressure at elevated temperature (RAPET). On the basis of rotating ring–disk electrode (RRDE) experiments, oxygen reduction activity was observed on all Ru_<i>x</i>P materials. Characteristic kinetic parameters show specific exchange current densities in the range of 0.4–1.4 mA mg^–1, Tafel slopes of 129–135 mV dec^–1, and %H₂O₂ of 3–11% of the total current. Complementary XPS and Raman spectral analysis reveals a highly oxidized surface with significant presence of PO₄^3– and RuO₂ species. To the best of our knowledge, this is the first report identifying oxygen reduction activity on Ru_<i>x</i>P

Sn-based atokite alloy nanocatalyst for high-power dimethyl ether fueled low-temperature polymer electrolyte fuel cell

Next-generation fuels are defined as those produced from non-food resources. A leading member in this group is dimethyl ether− DME (C2H6O), which is a high-energy, non-toxic gas, produced from a wide range of carbon feedstocks and wastes. We explored the oxidation of DME on a highly active catalyst based on Pt3Pd3Sn2 with an atokite structure in comparison to Pt3Sn and Pd3Sn. Following a comprehensive characterization of the new ternary catalyst by electron microscopy, X-ray diffraction, and photoelectron spectroscopy, the DME anodic reaction was analyzed by electrochemical online mass spectrometry of fuel cell gas emission product and supported by density functional theory (DFT) calculations. Pt3Pd3Sn2 catalyst exhibits optimal binding energy (−0.21 eV) and the lowest activation energy for electrochemical oxidation of DME (48.7 kJ mol−1 at 0.80 V). A few preferred oxidation routes were examined at different potentials corroborating with the identified CO2, formic acid, methanol, and methyl-formate by in-operando online mass spectrometry. Fuel-cell constructed using a Pt3Pd3Sn2/C anode catalyst and commercial Pt/C cathode catalyst, delivered an open circuit voltage of 0.9 V, a peak power density of 220 mW cm−2 at 0.40 V, and a gravimetric power density of 135 mW mgpgm−1 at ambient pressure and 80 °C, which exceeded the highest values reported so far for direct DME fuel cells

Volumetric cell-and-portal generation

We present an algorithm to generate a cell-and-portal decomposition of general indoor scenes. The method is an adaptation of the 3D watershed transform, computed on a distance-to-geometry sampled field. The watershed is processed using a flooding analogy in the distance field space. Flooding originates from local minima, each minimum producing a region. Portals are built as needed to avoid the merging of regions during their growth. As a result, the cell-and-portal decomposition is closely linked to the structure of the models. In a building, the algorithm finds all the rooms, doors and windows. To restrict the memory load, a hierarchical implementation of the algorithm is presented. We also explain how to handle possible model degeneracies -such as cracks, holes and interpenetrating geometries- using a pre-voxelisation step. The hierarchical algorithm, preceded when necessary by the pre-voxelisation, was tested on a large range of models. We show that it is able to deal with classical architectural models, as well as cave-like environments and large mixed indoor/outdoor scenes. Thanks to the intermediate distance field representation, the algorithm can be used regardless of the way the model is represented: it deals with parametric curves, implicit surfaces, volumetric data and polygon soups in a unified way.SCOPUS: cp.jFLWINinfo:eu-repo/semantics/publishe