Fuel cells

The work reviews the influence of gas impurities in fuel and oxidizing chemical on the alkaline oxyhydrogen fuel cell functioning. It shows that methane impurities act differently on anode and cathode, while other gases (except noble gases), including carbon monoxide, which is a poison for fuel cell with acid solution, influence the operation of alkaline fuel cell through the reaction with potassium hydroxide (KOH). Substitution electrolyte for fresh recovers fuel cell performance.

Using complex models, including the solution percolation problem and electrochemical kinetics calculations are considered the features of a solid polymer fuel cell catalyst layers with a catalyst based on nanoscale carbon materials, including graphene nanowires. These calculations are consistent with the experimental data presented by optimizing the composition of the catalyst layers. It is shown that the addition of 20 wt.\% nanofibres graphene can reduce ohmic losses from the ion current and improve the performance of the fuel cell is 20%

New mechanisms of oxygen reduction on perovskite related oxides LaL_i0.1M_0.1Fe_0.8O_3-d (M = Fe, Co, Ni) and a rock salt type oxide Li_0.1Ni_0.9O have been proposed. Based on these mechanisms, a comparison of catalytic activity of the oxides in the temperature range 820–1000 K has been done. It has been shown that catalytic activity of LaLi0.Co0.1Fe0.8O3-d oxide exceeds the activity of Li0.1Ni0.9O below 970 K

This work considers the application of graphene while forming the electrodes in biofuel cells. Graphene displays a number of important characteristics including first of all good mechanical properties, high thermal conductivity, high specific surface area, biocompatibility, structural peculiarities of a molecule, is available for chemical modification of the structure. Fabrication, properties of graphene and its oxide were considered and the peculiarities of the application of graphene as a basic material for electrodes in biofuel cells are also discussed.

This paper presents polarization characteristics of porous gas diffusion cathodes prepared from LaLi0.1M0.1Fe0.8O3-d (M = Fe, Co, Ni) oxides with a perovskite related structure and Li0.1Ni0.9O oxide with a rock salt structure. The characteristics were measured in the laboratory scale fuel cell in the temperature range 820–1000 K. It has been shown that electrochemical activity of the cathodes with Co and Ni additives exceeds the activity of the Li0.1Ni0.9O cathode below 970 K.

Features of current generation processes in MEA of hydrogen-air (oxygen) fuel cells with proton-conducting (acidic) and anion-conducting (alkaline) solid polymer electrolytes were compared. Certain parameters of electrode reactions and characteristics of electrolytes and interaction effects of MEA’s components in FC operation and also destabilizing factors which deriving direct from current flow as well as from presence of impurities in the fuel and oxidant were discussed.

The synthesis of catalysts 20 Au/C with different degree of dispersion. These systems were investigated for activity in the oxygen electroreduction reaction with methods of the cyclic voltammograms and polarization curves. The increase of rate and depth of process (the number of electrons increases from 2 to 3.5) in the transition from compact to gold nanoparticles.

By the example of tubular oxygen-permeable membrane of mixed-conducting LaGa_0.65Mg_0.15Ni_0.20O_3-Δ operating under oxygen chemical potential gradients in the regime of hydrocarbon oxidation, modeling of chemically induced strains in the dense ceramic material has been carried out. The membranes with various radii in different reactor configurations were simulated. Analysis of the distributions of oxygen chemical activity and chemically induced stresses showed that, for minimization of mechanical stresses, the most advantageous basic configuration involves supplying atmospheric air inside a tubular membrane and opposite directions of the gas flows. The maximum stresses are observed in the region of reducing gas mixture injection, where a zone with an essentially constant oxygen chemical potential on the membrane surface may exist for many reactor configurations. The size of such zones formed due to specific features of the gaseous phase component distribution and/or ceramic reactor configurations, has a significant effect on the mechanical stress distribution.

Composition and structure of proton-exchange membrane (PEM) fuel cell catalytic layers were investigated. The maximum FC efficiency was observed at the polymer content in a layer 25-30 vol.% at work on air and 30-35 vol. % at work on oxygen. At a variation of quantity of catalytic composition the maximum current density have been received at layer load 1.75 mg/sm², thus decrease in it value in 2 times leads to falling of current density only on 10%.

The performance of several redox mediators (methylene blue, neutral red. and gallocyanine) in the bioelectrochemical system glucosc- Escherichia coli cells was estimated by means of the rotating disk electrode technique. The diffusion coefficients of the mediators under study were evaluated. Methylene blue and gallocyanine arc shown to be effective reversible electron carriers for the Escherichia coli-based bioanode.