Methods are provided for tailoring multi-step chemical reactions having competing elementary steps using a strained catalyst. In various aspects, a layered piezo-catalytic system is provided, and may include a metal catalyst overlayer disposed on a piezo-electric substrate. The methods include applying a voltage bias to the piezo-electric substrate of the piezo-catalytic system resulting in a strained catalyst having an altered catalytic activity as a result of one or both of a compressive stress and tensile stress. The methods include exposing reagents for at least one step of the multi-step chemical reaction to the strained catalyst, and catalyzing the at least one step of the multi-step chemical reaction. In various aspects, the methods may include using an oscillating voltage bias applied to the piezo-electric substrate.

Methods are provided for tailoring multi-step chemical reactions having competing elementary steps using a strained catalyst. In various aspects, a layered piezo-catalytic system is provided, and may include a metal catalyst overlayer disposed on a piezo-electric substrate. The methods include applying a voltage bias to the piezo-electric substrate of the piezo-catalytic system resulting in a strained catalyst having an altered catalytic activity as a result of one or both of a compressive stress and tensile stress. The methods include exposing reagents for at least one step of the multi-step chemical reaction to the strained catalyst, and catalyzing the at least one step of the multi-step chemical reaction. In various aspects, the methods may include using an oscillating voltage bias applied to the piezo-electric substrate.

Catalyst comprising a first layer having an outer layer with a layer comprising Pt directly thereon, wherein the first layer has an average thickness in a range from 0.04 to 30 nanometers, and wherein the layer. Catalysts described herein are useful, for example, in fuel cell membrane electrode assemblies.

Catalyst comprising a first layer having an outer layer with a layer comprising Pt directly thereon, wherein the first layer has an average thickness in a range from 0.04 to 30 nanometers, and wherein the layer. Catalysts described herein are useful, for example, in fuel cell membrane electrode assemblies.

Apparatuses and methods of measuring a hydrogen diffusivity of a metal structure including during operation of the metal structure, are provided. A hydrogen charging surface is provided at a first location on an external surface of the structure. In addition, a hydrogen oxidation surface is provided at a second location adjacent to the first location on the external surface of the structure. Hydrogen flux is generated and directed into the metal surface at the charging surface. At least a portion of the hydrogen flux generated by the charging surface is diverted back toward the surface. A transient of the diverted hydrogen fluxes measured, and this measurement is used to determine the hydrogen diffusivity of the metal structure in service.

A separator for a fuel cell includes a plurality of channels; and an inlet hole and an outlet hole formed in a first side and a second side of the plurality of channels, respectively, such that a reaction gas flows into and out from the separator to be exposed to a reaction surface including a membrane electrode assembly. The inlet hole is larger in size than the outlet hole.

A separator for a fuel cell includes a plurality of channels; and an inlet hole and an outlet hole formed in a first side and a second side of the plurality of channels, respectively, such that a reaction gas flows into and out from the separator to be exposed to a reaction surface including a membrane electrode assembly. The inlet hole is larger in size than the outlet hole.

An active layer for a proton-exchange membrane fuel cell (PEMFC) including at least two perfluorosulfonate ionomers.

An active layer for a proton-exchange membrane fuel cell (PEMFC) including at least two perfluorosulfonate ionomers.

Various embodiments may comprise an ion exchange membrane (IEM) redox flow cell comprising a IEM, a negative electrode in contact with a reactive fluid, a liquid electrolyte comprising reactants, a positive electrode in contact with the liquid electrolyte, and a diffusion barrier layer disposed between the IEM and the positive electrode, and wherein the negative electrode is isolated from the positive electrode by the IEM.