Disclosed herein are doped perovskite oxides. The doped perovskite oxides may be used as a cathode material in an electrochemical cell to electrochemically generate ammonia from N.sub.2. The doped perovskite oxides may be combined with nitride compounds, for instance iron nitride, to further increase the efficiency of the ammonia production.

The present invention provides an alkaline water electrolysis anode such that even when electric power having a large output fluctuation, such as renewable energy, is used as a power source, the electrolysis performance is unlikely to be deteriorated and excellent catalytic activity is retained stably over a long period of time. The alkaline water electrolysis anode is an alkaline water electrolysis anode 10 provided with an electrically conductive substrate 2 at least a surface of which contains nickel or a nickel base alloy and a catalyst layer 6 disposed on the surface of the electrically conductive substrate 2, the catalyst layer 6 containing a metal composite oxide having a quadruple perovskite oxide structure, wherein the metal composite oxide contains calcium (Ca), manganese (Mn), and nickel (Ni), and has an atom ratio of Ca/Mn/Ni/O of (1.0)/(6.6 to 7.0)/(0.1 to 0.4)/12.0.

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 of carbon dioxide hydrogenation comprises introducing gaseous water to a positive electrode of an electrolysis 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 comprises an electrolyte material having an ionic conductivity greater than or equal to about 10-2 S/cm at one or more temperatures within a range of from about 150° C. to about 650° C. Carbon dioxide is introduced to the negative electrode of the electrolysis cell. A potential difference is applied between the positive electrode and the negative electrode of the electrolysis cell to generate hydrogen ions from the gaseous water that diffuses through the proton-conducting membrane and hydrogenates the carbon dioxide at the negative electrode. A carbon dioxide hydrogenation system is 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 NH.sub.3, and an electrochemical cell are also described.

Provided are: an oxygen catalyst that uses an alkaline aqueous solution as an electrolyte and has high catalytic activity; and an electrode. The oxygen catalyst according to the present invention is an oxygen catalyst in which an alkaline aqueous solution is used as an electrolyte, the oxygen catalyst being characterized by having a pyrochlore oxide structure including bismuth on an A-site and ruthenium on a B-site, and containing manganese as well as bismuth and ruthenium. The electrode according to the present invention is characterized by using the oxygen catalyst according to the present invention.

A method for producing ammonia comprises introducing a first feed stream to a positive electrode of an electrochemical cell. The electrochemical cell comprises the positive electrode, a negative electrode, and an electrolyte between the positive electrode and the negative electrode. A second feed stream comprising a nitrogen source is introduced to the negative electrode and a potential difference is applied between the positive electrode and the negative electrode to produce hydrogen ions, a first product stream comprising carbon monoxide, and a second product stream comprising ammonia. Additional methods and systems are disclosed.

A catalyst material for enhancing hydrogen and oxygen production includes algae-derived carbon scaffolds; and catalyst components coupled to the algae-derived carbon scaffolds. The catalyst material has excellent oxygen evolution reaction (OER) performance superior to that of a benchmark OER catalyst Ir/C.

Disclosed is a biphasic electrically conductive perovskite-based mixed oxide of the structure ABO.sub.3 with A=Ba, and B=Co, comprising additionally 5-45 at %, preferably 15 to 30 at %, particularly preferably 25 at % Co.sub.3O.sub.4 (at % Co based on the total number of Co atoms in the perovskite ABO.sub.3 and 0.5 to 0.3 at %, preferably 1 to 2.5 at %, particularly preferably 2 at % (wherein the at % are referred to the total number of B cations in the perovskite ABO.sub.3) Ti as dopant. Preferably, the mixed oxide has the stoichiometric formula BaCo.sub.1−xTi.sub.xO.sub.3−δ:Co.sub.3O.sub.4 with x=0.005 to 0.03, preferably x=0.01 to 0.025, particularly preferably x=0.02, wherein δ defines the vacancies in the perovskite structure and is in the range of about 0.1 to 0.8, preferably 0.3 to 0.7, particularly preferably about 0.5 to 0.6. Further disclosed are a catalyst and an anode comprising the mixed oxide, the use of the catalyst in alkaline water electrolysis or in metal-air batteries, the use of the mixed oxide for the preparation of an anode for alkaline water electrolysis or metal-air batteries. Further, manufacturing processes for a precursor solution for the mixed oxide and for the inventive anode are disclosed, as well as an amorphous mixed oxide having a Co:Ba ratio of about 2:1 and a TTB (Tetragonal Tungsten-Bronze)-like near structure obtainable by using the mixed oxide according to the invention as catalyst in the oxygen evolution reaction of alkaline water electrolysis, whereby said amorphous product is formed by leaching out Ba.

An oxygen generation electrode includes, a conductive layer including a salt of stannic acid, the salt of stannic acid having a perovskite structure, a light absorption layer disposed on the conductive layer, and a catalyst layer disposed on the light absorption layer, the catalyst layer including an oxide having a perovskite structure and being responsible for an oxygen evolution reaction, the conductive layer being doped to degeneracy with impurities, the light absorption layer forming a Type-II heterojunction with the conductive layer, the catalyst layer being doped to degeneracy with impurities, the upper end of the valence band of the catalyst layer being higher than the upper end of the valence band of the light absorption layer.