This method for producing a vanadium compound has an alkaline leaching step for immersing incineration ash in an alkaline solution to cause vanadium to leach from the incineration ash into the alkaline solution and obtain a leachate slurry, a solid-liquid separation step for separating the leachate slurry obtained in the alkaline leaching step into a solid and liquid followed by removing insoluble matter to obtain a leachate, a pH adjustment step for adding acid to the leachate following solid-liquid separation to make the leachate acidic, an aging step for aging the leachate following pH adjustment until a precipitate forms in the leachate, and a separation step for separating the precipitate from the leachate following the aging step.

Methods and systems for removing impurities from electrolyte solutions having three or more valence states. In some embodiments, a method includes electrochemically reducing an electrolyte solution to lower its valence state to a level that causes impurities to precipitate out of the electrolyte solution and then filtering the precipitate(s) out of the electrolyte solution. In embodiments in which the electrolyte solution is desired to be at a valence state higher than the precipitation valence state, a method of the disclosure includes oxidizing the purified electrolyte solution to the target valence.

Methods and systems for removing impurities from electrolyte solutions having three or more valence states. In some embodiments, a method includes electrochemically reducing an electrolyte solution to lower its valence state to a level that causes impurities to precipitate out of the electrolyte solution and then filtering the precipitate(s) out of the electrolyte solution. In embodiments in which the electrolyte solution is desired to be at a valence state higher than the precipitation valence state, a method of the disclosure includes oxidizing the purified electrolyte solution to the target valence.

A technique for exfoliating a transition metal dichalcogenide material to produce separated nano-scale platelets includes combining the transition metal dichalcogenide material with a liquid to form a slurry, wherein the transition metal dichalcogenide material includes layers of nano-scale platelets and has a general chemical formula MX.sub.2, and wherein M is a transition metal and X is sulfur, selenium, or tellurium. The slurry of the transition metal dichalcogenide material is treated with an oxidant to form peroxo-metalate intermediates on an edge region of the layers of nano-scale platelets of the transition metal dichalcogenide material. The peroxo-metalate intermediates is treated with a reducing agent to form negatively charged poly-oxo-metalates to induce separation of the transition metal dichalcogenide material into the separated nano-scale platelets of the transition metal dichalcogenide material.

Provided is the positive electrode active material for a potassium ion battery according to the embodiment comprises a compound represented by Formula (1), in which M represents at least one element selected from the group consisting of V, Fe, Co, Ni, and Mn, and x represents a number from 0 to 1; and is a positive electrode for a potassium ion battery comprising the positive electrode active material for a potassium ion battery according to the embodiment, or a potassium ion battery comprising the positive electrode for a potassium ion battery.

KMO.sub.xPO.sub.4F.sub.1-x[Formula (1)]

The present disclosure relates generally to electrocatalytic process for conversion of a hydrocarbon reactant, comprising: introducing the hydrocarbon reactant into an acidic solution in a presence of a catalyst, wherein the catalyst includes a d? transition metal-oxo moiety; and applying an electrical input to the catalyst to convert the hydrocarbon reactant into a product. The present disclosure also relates to a catalyst for conversion of a hydrocarbon reactant, comprising a d? transition metal-oxo moiety and a sulfonic moiety bonded to the d? transition metal.

A CoVO.sub.x composite electrode and method of making is described. The composite electrode comprises a substrate with an average 0.5-5 ?m thick layer of CoVO.sub.x having pores with average diameters of 2-200 nm. The method of making the composite electrode involves contacting the substrate with an aerosol comprising a solvent, a cobalt complex, and a vanadium complex. The CoVO.sub.x composite electrode is capable of being used in an electrochemical cell for water oxidation.

An electro-active material, including a mixture of a first component including at least a first compound of formula (I) Li.sub.xMnO.sub.y and a second component including at least a second compound of formula (II) Li.sub.xH.sub.yV.sub.3O.sub.8, wherein in formula (I): 0x2, 1y3, and 22yx5, and wherein in formula (II): 0x4.5, 0.01y2, and 0.01x+y6.5. The first compound is in the form of particles having a certain particle size and the second compound is in the form of nanoparticles having a certain particle size or nanofibers having certain dimensions. The first and second components are present in amounts of 1:99% to 99:1% by weight, and the mixture, upon being mechanically pressed in a range of 20 to 70 KN with a die, has a synergic effect of pressed density (SEPD) greater than 100%.

An electro-active material, including a mixture of a first component including at least a first compound of formula (I) Li.sub.xMnO.sub.y and a second component including at least a second compound of formula (II) Li.sub.xH.sub.yV.sub.3O.sub.8, wherein in formula (I): 0x2, 1y3, and 22yx5, and wherein in formula (II): 0x4.5, 0.01y2, and 0.01x+y6.5. The first compound is in the form of particles having a certain particle size and the second compound is in the form of nanoparticles having a certain particle size or nanofibers having certain dimensions. The first and second components are present in amounts of 1:99% to 99:1% by weight, and the mixture, upon being mechanically pressed in a range of 20 to 70 KN with a die, has a synergic effect of pressed density (SEPD) greater than 100%.

Provided are the following: a mixture of visible light-responsive photocatalytic titanium oxide fine particles which can conveniently produce a photocatalyst thin film that exhibits photocatalyst activity even with only visible light (400-800 nm) and that exhibits high transparency; a dispersion liquid of the fine particles; a method for producing the dispersion liquid; a photocatalyst thin film; and a member having the photocatalyst thin film on a surface thereof. The mixture of visible light-responsive photocatalytic titanium oxide fine particles is characterized by containing two kinds of titanium dioxide fine particles: first titanium oxide fine particles, in which a tin component and a transition metal component (excluding an iron group element component) that increases visible light response properties form a solid solution, and second titanium oxide fine particles, in which an iron group element component and a chromium group element component form a solid solution.