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.

Materials for electrochemical cells are provided. BaZr.sub.0.4Ce.sub.0.4M.sub.0.2O.sub.3 compounds, where M represents one or more rare earth elements, are provided for use as electrolytes. PrBa.sub.0.5Sr.sub.0.5Co.sub.2−xFe.sub.xO.sub.5+δ is provided for use as a cathode. Also provided are electrochemical cells, such as protonic ceramic fuel cells, incorporating the compounds as electrolytes and cathodes.

A composition consisting essentially of a perovskite crystalline structure includes ions of a first metal M1 which occupies an A-site of the perovskite crystalline structure and ions of a second metal M2 which occupies a B-site of the perovskite crystalline structure. M2 has two oxidation states capable of forming a redox couple suitable for reversibly catalyzing an oxygen reduction reaction (ORR) and an oxygen evolution reaction (OER). The composition also includes ions of a third metal M3 at least a portion of which substitutes for M1 in the A-site of the perovskite crystalline structure, and at least a portion of which optionally also substitutes for M2 in the B-site of the perovskite crystalline structure. At least some of the ions of M3 have a different oxidation state to the ions of M1. The composition also includes atoms of an element X, which is a chalcogen.

An electrochemical cell includes a fuel electrode, an air electrode containing a perovskite type oxide as a main component, the perovskite type oxide being represented by a general formula ABO.sub.3 and containing La and Sr at an A site, and a solid electrolyte layer arranged between the fuel electrode and the air electrode. The air electrode includes a first portion and a second portion, the first portion being located on a side opposite to the solid electrolyte layer, the second portion being located on the solid electrolyte layer side. A first ratio of an La concentration to an Sr concentration detected at the first portion through Auger electron spectroscopy is at least 1.1 times a second ratio of an La concentration to an Sr concentration detected at the second portion through Auger electron spectroscopy.

The perovskite compound according to the invention has a cubic perovskite structure, has high catalytic activity in oxygen reduction and evolution reactions, and has excellent durability, and thus, can be used as a catalyst of electrochemical devices, particularly as a fuel cell catalyst.

Described herein are solid oxide fuel cells comprising conductive layers and methods of fabricating such cells. Specifically, a solid oxide fuel cell comprises cathode and anode layers, each comprising a porous base, catalyst sites disposed within the base, and a conductive layer. The conductive layer provides electrical conduction between the corresponding current collector and the catalyst sites. The conductive layer may at least partially extend into the porous base. For example, at least a portion of the conductive layer may be formed by infiltration of the porous base, e.g., before catalyst infiltration. In some examples, at least a portion of the conductive layer forms an interface between the corresponding porous base and the current collector. In these examples, the conductive layer is formed from an initial (green) conductive layer that is stacked between layers used to form the porous base and current collector and sintered the stack.

A cathode in a solid oxide fuel cell containing AgPrCoO.sub.3. The operating temperature range of the cathode is from about 400° C. to about 850° C.

This electrode comprises: an electrode component containing a columnar structure; and a porous collector layer that is prepared on the electrode component. The columnar structure comprises a multiple columnar sections, the lateral surfaces of which are at least partially in contact with each other. Each columnar part section is provided with a multilayer part wherein different inorganic compound layers are stacked. In addition, the columnar structure comprises two or more adjacent columnar sections, which are different from each other in the stacking direction of the multilayer part. For example, each columnar section has a width of 10 nm to 100 nm, and each inorganic compound layer has a thickness of 1 nm to 10 nm.

A solid oxide electrochemical cell includes a solid oxide electrolyte, an anode located on a first side of the solid oxide electrolyte, and a cathode located on a second side of the solid oxide electrolyte. The cathode includes lanthanum nickel ferrite.

A solid oxide fuel cell comprising an anode layer, an electrolyte layer, and a two phased cathode layer. The two phased cathode layer comprises praseodymium and gadolinium-doped ceria. Additionally, the solid oxide fuel cell does not contain a barrier layer.