A calcium ruthenate composition of matter includes a compound of calcium, ruthenium and oxygen with a chemical formula of Ca.sub.aRu.sub.bO.sub.c and with ‘a’ greater than or equal to 2.75 and less than or equal to 3.25, ‘b’ greater than or equal to 0.75 and less than or equal to 1.25, and ‘c’ greater than or equal to 5.75 and less than or equal to 6.25. The Ca.sub.aRu.sub.bO.sub.c is an oxygen evolution reaction catalyst, an oxygen reduction reaction catalyst, and/or a catalyst for the hydrolysis of a hydrogen containing compound.

A solid oxide electrochemical cell includes a solid oxide electrolyte, a fuel-side electrode located on a first side of the solid oxide electrolyte, and an air-side electrode located on a second side of the solid oxide electrolyte. The air-side electrode includes a strontium getter material, a current collector layer and a functional layer located between the current collector layer and the second side of the solid oxide electrolyte.

An electrochemical cell comprises a first electrode, a second electrode, and a proton-conducting membrane between the first electrode and the second electrode. The first electrode comprises a layered perovskite having the general formula: DAB.sub.2O.sub.5+δ, wherein D consists of two or more lanthanide elements; A consists of one or more of Sr and Ba; B consists of one or more of Co, Fe, Ni, Cu, Zn, Mn, Cr, and Nd; and δ is an oxygen deficit. The second electrode comprises a cermet material including at least one metal and at least one perovskite. Related structures, apparatuses, systems, and methods are also described.

A method of a hydrocarbon product and ammonia comprises introducing C.sub.2H.sub.6 to a positive electrode of an electrochemical cell comprising the positive electrode, a negative electrode, and a proton-conducting membrane between the positive electrode and the negative electrode. The proton-conducting membrane comprising an electrolyte material having an ionic conductivity greater than or equal to about 10.sup.−2 S/cm at one or more temperatures within a range of from about 150° C. to about 600° C. N.sub.2 is introduced to the negative electrode of the electrochemical cell. A potential difference is applied between the positive electrode and the negative electrode of the electrochemical cell. A system for co-producing higher hydrocarbons and NH3, and an electrochemical cell are also described.

A perovskite-type oxide catalyst for water-splitting reactions is provided. The catalyst, Ca.sub.2-ySr.sub.yFe.sub.1-xCo.sub.1-xMn.sub.2xO.sub.6-δ where y=0.10-1.90 and x=0.05-0.95, has catalytic activity for both hydrogen- and oxygen-evolution reactions. An exemplary catalyst is CaSrFe.sub.0.75Co.sub.0.75Mn.sub.0.5O.sub.6-δ.

A CaTiO.sub.3—TiO.sub.2 composite electrode and method of making is described. The composite electrode comprises a substrate with an average 2-12 μm thick layer of CaTiO.sub.3—TiO.sub.2 composite particles having average diameters of 0.2-2.2 μm. The method of making the composite electrode involves contacting the substrate with an aerosol comprising a solvent, a calcium complex, and a titanium complex. The CaTiO.sub.3—TiO.sub.2 composite electrode is capable of being used in a photoelectrochemical cell for water splitting.

A method and a composition to stabilize the surface cation chemistry of the perovskite or related oxides, and thus, to minimize or completely avoid the detrimental segregation and phase separation of dopant cations at the surface can include modifying the surface with more oxidizable metal cations and/or more oxidizable metal oxides, thereby reducing the oxygen vacancy concentration at the very surface.

The oxygen evolution reaction (OER) system includes a bismuth strontium cobalt oxide.

According to embodiments of the present disclosure, a method of producing hydrogen in a fuel cell includes passing ammonia under pressure to an anode of the fuel cell, where the ammonia is decomposed into nitrogen gas and protons. The fuel cell comprises a cathode, the anode, and a proton-conducting electrolyte between the anode and the cathode. The anode includes an ammonia decomposition catalyst. The method further includes passing the purging the nitrogen from the anode, passing the protons through the proton-conducting electrolyte to the cathode, and passing the electrons from the anode to the cathode, wherein the protons and the electrons react to produce substantially pure hydrogen gas under pressure.

The present disclosure discloses an ABO.sub.3 type high-entropy perovskite Ba.sub.x(FeCoNiZrY).sub.0.2O.sub.3-δ electrocatalytic material and a preparation method thereof, belonging to the technical field of electrocatalytic materials. The electrocatalytic material is prepared by taking hydrated cobalt nitrate, hydrated ferric nitrate, hydrated nickel nitrate, barium nitrate, hydrated yttrium nitrate, hydrated zirconium nitrate and polyacrylonitrile staple fibers as raw materials through processes of liquid phase chelation, gelation, calcination, etc. The prepared high-entropy perovskite Ba.sub.x(FeCoNiZrY).sub.0.2O.sub.3-δ electrocatalytic material can release more electrochemical active sites due to its special nanostructure, thus showing better electrocatalytic activity. Meanwhile, by adjusting the stoichiometric ratio of A/B-site metals, the electronic structure change of five metals in a catalytic center and the change of an oxygen vacancy content are realized, and the purpose of adjusting and optimizing the nitrogen reduction performance is achieved, so that the electrocatalytic material has excellent electrocatalytic conversion of nitrogen gas into ammonia gas.