1562 results about "Composite oxide" patented technology

The invention discloses a multi-component composite oxide dispersion strengthening molybdenum alloy and a preparation method thereof, and relates to the technical field of refractory metal powder metallurgy preparation. The molybdenum alloy comprises a molybdenum matrix and a Y-X-O composite oxide nano precipitated phase dispersed and distributed in the molybdenum matrix. The molybdenum alloy comprises the following components in percentage by mass: 1%-2% of Y2O3, 0.3%-1.2% of an active element X, 96.5%-98.7% of molybdenum and inevitable impurities, wherein X is selected from one of Ti, Zr and Hf; the Y-X-O composite oxide nano precipitated phase and the molybdenum matrix form a coherent or semi-coherent interface, and the interface mismatch degree is less than or equal to 5%. The molybdenum alloy has excellent high-temperature strength and creep resistance, and can be applied to the high-temperature fields of nuclear industry, aerospace and the like.

The invention provides a low-cost high-specific-surface-area cerium-aluminum composite oxide, a preparation method and application thereof, and relates to the technical field of catalysts, the preparation method comprises the following steps: step S1, adding 10-40% of cerium salt, 50-90% of aluminum salt and 0-10% of lanthanum source or zirconium source into deionized water, stirring and mixing, filtering, and washing to be neutral to obtain a cerium-containing solution; step S2, impregnating an alumina carrier in the cerium-containing solution prepared in the step S1, and standing to enable the cerium-containing solution to be impregnated on the alumina carrier, so as to obtain impregnated slurry; and S3, drying the dipping slurry, and then roasting in an inert atmosphere to obtain the cerium-aluminum composite oxide. The stable cerium-aluminum composite material is formed by doping one of lanthanum and zirconium with different masses into aluminum oxide or cerium oxide, the problem that the adsorption capacity of a traditional ammonia trapping method is limited is effectively solved, and the adsorption capacity of the material to ammonia is remarkably improved.

The invention discloses an annular furnace heat-resistant supporting forged chassis and an additive manufacturing process and a fixing device thereof, and belongs to the technical field of plating of metal materials, and the annular furnace heat-resistant supporting forged chassis comprises the steps that heat-resistant alloy steel base metal with specific components is prepared; carrying out laser texturing and nickel-based alloy bottom layer pretreatment on the surface of the steel plate; performing laser cladding on high-silicon high-temperature alloy powder containing niobium and rare earth elements to form a functional cladding layer, and performing gradient cladding on the edge of the atmosphere guide hole; and finally, carrying out heat treatment and assembling with a fan-shaped refractory brick fixing device. A composite oxide film and a multi-scale strengthening system are constructed, hydrogen resistance and brittleness resistance are effectively achieved, interface thermal stress is relieved, cracking and stripping of a cladding layer are avoided, a fixing device adapts to thermal expansion, the atmosphere is dredged, and the annealing uniformity of a steel coil is improved; the problems of creep deformation, hydrogen embrittlement, cladding layer stripping and thermal stress cracking of a traditional supporting component under the conditions of high temperature, heavy load and nitrogen and hydrogen atmosphere are solved.

The invention relates to the technical field of coating materials, and discloses a pure titanium micro-arc oxidation coating for a vacuum cup and a preparation method thereof.The preparation method comprises the following steps that surface pretreatment is conducted, specifically, a pure titanium vacuum cup inner container workpiece is sequentially subjected to degreasing, acid pickling and ultrasonic cleaning; preparing an electrolyte, namely adding 15-25 parts by weight of a silicon-containing compound, 5-12 parts by weight of metal salt, 3-8 parts by weight of an antibacterial agent and 1-5 parts by weight of a stabilizer into deionized water, and controlling the pH value to be 8.5-10.5; and performing micro-arc oxidation treatment. According to the invention, a silane compound in the micro-arc oxidation electrolyte contains a high-activity silanol group which is subjected to condensation reaction with titanium hydroxyl on the surface of a pure titanium substrate under the action of an electric field to form stable covalent bonding, so that the bonding strength of the coating and the substrate is enhanced; metal ions generated by metal salt electrolysis are co-deposited with titanium ions through plasma discharge, a composite oxide structure is constructed, and micro defects on the surface of a titanium substrate are sealed.

The invention relates to a preparation method of a pectin-derived carbon-coated amorphous tin-zinc composite oxide lithium ion battery negative electrode material. The method comprises the following steps: dropwise adding a tin tetrachloride solution and an acidified zinc oxide solution into a pectin solution to obtain a metal ion-pectin dispersion liquid; adding ammonia water to obtain a pectin precursor solution; freezing and solidifying with liquid nitrogen; and after freeze-drying, roasting for 3-5 hours to obtain the pectin derived carbon coated amorphous tin-zinc composite oxide lithium ion battery negative electrode material. The reversible specific capacity of the obtained composite material reaches 1339 mA h g <-1 > after 100 cycles under the current density of 0.2 A g <-1 >.

The invention discloses modified biogas residue-based hydrothermal carbon, a preparation method thereof and a dry digestion method for kitchen waste, and belongs to the technical field of waste organic matter recycling. The preparation method comprises the following steps: soaking biogas residues in a phosphoric acid solution to obtain pretreated biogas residues; mixing the pretreated biogas residues, transition metal salt, biochar loaded with vitamin B12 and water with the mass being 8-15 times that of the pretreated biogas residues, and performing hydrothermal reaction for 1-4 hours under the conditions that the temperature is 180-250 DEG C and the pressure is 1.5-4 MPa to obtain a hydrothermal product; and activating the hydrothermal product for 1-2 hours under the protective atmosphere of 300-400 DEG C to obtain the modified biogas residue-based hydrothermal carbon. The surface Fe-Cu composite oxide sequentially catalyzes and oxidizes H2S into elemental sulfur and sulfate ions, the vitamin B12-loaded biochar can promote MA directional proliferation, the sulfate ions can competitively inhibit SRB substrate uptake, the quantity ratio of MA to SRB is increased, and the methane production efficiency is effectively improved.

The invention discloses a method for preparing glyceric acid by catalytically oxidizing glycerol with a non-noble metal catalyst, which comprises the following steps of: catalytically oxidizing glycerol under the action of oxygen by taking a CuZrOx composite oxide as a catalyst to obtain glyceric acid; wherein the CuZrOx composite oxide is prepared by a deposition-precipitation method through high-temperature calcination. The internal structure of the catalyst is changed due to introduction of Cu, two metal components are combined more tightly and have strong interaction due to doping of Cu, and meanwhile, compared with a single-metal catalyst, the number of oxygen vacancies of the composite oxide catalyst is increased, the number of strongly acidic sites and strongly basic sites on the surface is increased, and the catalytic activity of the catalyst is improved. According to the present invention, the catalyst has a certain acid-base property so as to produce the good catalysis effect, such that the high glycerol conversion rate and the high glyceric acid selectivity are achieved while the production cost is reduced, and the catalyst can be repeatedly used.

This positive electrode active material for nonaqueous electrolyte secondary batteries contains a lithium transition metal composite oxide that is represented by composition formula LixMnyNizPaMbO2-cFc(wherein M represents at least one element that is selected from among Ti, Co, Si, Sr, Nb, W, Mo, Ca, Mg, Sb, Na, B, V, Cr, Fe, Cu, Zn, Ge, Zr, Ru, K and Bi; 1.0<x≤1.2; 0.4≤y≤0.8; 0≤z≤0.4; 0<a<0.01; 0<b<0.05; 0<c<0.1; and (x+y+z+a+b)≤2).

The invention relates to the technical field of batteries, in particular to a high-temperature-resistant lithium cobalt oxide positive electrode material and a preparation method and application thereof.The high-temperature-resistant lithium cobalt oxide positive electrode material comprises a lithium cobalt oxide matrix and a coating layer coating the surface of the lithium cobalt oxide matrix, the lithium cobalt oxide matrix is doped with Mg, Ti and La, and the coating layer is a fast ion coating layer of a Li-Gd-Ti-O4 spinel phase. Bulk phase doping is carried out through a high-temperature solid-phase method, Mg, Ti and La are doped in a lithium cobalt oxide matrix, and the lattice structure thermal stability of lithium cobalt oxide under high voltage (4.4 V) is improved; a fast ion coating layer of a Li-Gd-Ti-O4 spinel phase is formed on the surface of a lithium cobalt oxide matrix by adopting a solid phase method, and the comprehensive performance of the lithium cobalt oxide positive electrode material is improved through multiple mechanisms such as the lattice stabilization effect of rare earth ions, the interface barrier effect of composite oxide and lithium ion conductivity regulation and control; particularly, the capacity, the cycling stability, the thermal stability, the high-voltage tolerance and the like are realized.

The present invention provides a hydrogenation catalyst, and a preparation method therefor and a use thereof. The catalyst of the present invention comprises an active component and a carrier, wherein the active component is composed of Ni, Mo, and P, and the carrier is a composite oxide comprising magnesium oxide, aluminum oxide, and silicon oxide; and on the basis of the weight of the catalyst, the mass ratio of Ni to Mo in the active component is 1.1-5, preferably 1.9-2.3, and Ni is calculated as NiO and Mo is calculated as MoO3. The active component of the catalyst of the present invention contains a high content of nickel. When used for the second-stage hydrogenation of cracked gasoline, the catalyst can be suitable for treating a raw material having a higher diene content, shows relatively strong monoolefin saturation performance and desulfurization and denitrification activity, can effectively inhibit carbon deposition, and has high stability. Therefore, the catalyst of the present invention is particularly suitable for use in industrial production of the second-stage hydrogenation of cracked gasoline or a fraction thereof.

The invention discloses a preparation method and application of a carbon dioxide hydrogenation catalyst, and belongs to the field of hydrogenation catalysis. The vanadium slag is used as a raw material, a leaching solution containing silicon, chromium and vanadium is obtained through sodium salt roasting, an aluminum source is added to remove the silicon element, meanwhile, an ordered mesoporous carbon material is added, and silicon and aluminum elements are converted into an ordered mesoporous composite oxide which is used as a hydrogenation catalyst carrier; an indium salt, a cerium salt and a nickel salt are dissolved in ethanol and mixed with the carrier for isopyknic impregnation to obtain the hydrogenation catalyst; and carrying out chromium and vanadium separation on the silicon-removed leaching solution to obtain chromium sesquioxide and the all-vanadium redox flow battery electrolyte. The catalyst has a regular pore structure, ordered mesopores provide a confinement effect, dispersion and anchoring of active components are facilitated, and the activity of the catalyst is remarkably improved.

The invention provides a multi-component composite metal oxide nanosheet gradient coating polypropylene diaphragm and a preparation method and application thereof, and the multi-component composite metal oxide nanosheet gradient coating polypropylene diaphragm comprises a polypropylene substrate and a Ti-Fe-Zr ternary composite oxide nanosheet gradient coating coated on the surface of the substrate, the thickness of the coating is 1-2.5 [mu] m, a gradient structure in which the concentration of nanosheets decreases progressively is formed from the surface to a substrate, the thickness of a surface compact layer accounts for 30-40%, and the interlayer spacing is 1.0-2.0 nm. The diaphragm disclosed by the invention has excellent electrolyte affinity, ionic conductivity and thermal stability, and can effectively inhibit the growth of lithium dendrites and prolong the cycle life of the battery.

The invention discloses a method for generating 1234yf through one-step fluorination of 240db. The method comprises the following step: reacting 240db and hydrogen fluoride under the action of a fluorinated catalyst to generate 1234yf, the catalyst comprises a Ce-Zr composite oxide carrier and one or more than two of Ni, La, Cr, Co, Fe, Sb, Mo and Cu loaded on the carrier. The method disclosed by the invention has the characteristics of stable and controllable process and long service life of the catalyst while ensuring high selectivity and high yield, effectively reduces material consumption and equipment maintenance cost in industrial production, and overcomes the problems of economy and stability in large-scale production in the prior art.

The invention relates to an aerogel-derived ultralow-temperature water-sulfur poisoning-resistant flue gas denitration catalyst and a preparation method thereof, and belongs to the technical field of air pollution control and environment catalytic material frontier. CeMnNiOx composite oxide is used as an active component of the catalyst, a catalyst precursor gel with a three-dimensional network structure is formed through a sol-gel method, and then the hydrophobic aerogel derivative denitration catalyst with a high specific surface area, low density and a three-dimensional porous structure is obtained through aging, freeze drying and high-temperature heat treatment. The denitration efficiency of the catalyst can reach 90% or above at the temperature of 80-270 DEG C in a complex atmosphere containing 5-10% of water vapor and 50-100 ppm of SO2. The method is suitable for deep purification of NOx in ultralow-temperature and high-humidity SO2-containing complex flue gas after industrial desulfurization and dust removal.

The invention relates to the technical field of zinc-based material powder additive manufacturing, in particular to a zinc-based material powder additive manufacturing system and a manufacturing method thereof.The zinc-based material powder additive manufacturing method comprises the following steps that zinc-based alloy powder is obtained and subjected to surface activating treatment through plasma jet; determining cold spraying process parameters based on the oxygen content of the activated powder; cold spraying-laser composite deposition is executed, and compact green bodies are formed on the substrate layer by layer; and the metallurgical bonding state between deposits is determined, and selective laser remelting is triggered to eliminate interface defects. According to the method, a composite oxide layer is generated on the surface of the powder through Ar-mixed gas and plasma jet treatment with the power of 8-12 kW, excessive oxidation can be prevented, the powder activity can be improved, and a good foundation is laid for subsequent spraying deposition.

The invention relates to the technical field of organic synthetic chemistry, in particular to a preparation method of ethyl 2-n-butyl acetoacetate, which comprises the following specific steps: S1, preparation of a composite solid base catalyst, S2, synthesis of ethyl 2-n-butyl acetoacetate, S3, post-treatment of a reaction solution, and S4, separation and purification of a product. The preparation method has the following beneficial effects that the magnesium-aluminum composite oxide is used as a carrier, and the composite solid base catalyst loaded with potassium and lanthanum has relatively high catalytic activity and selectivity; the magnesium-aluminum composite oxide carrier has a relatively large specific surface area and rich alkaline sites, so that a good catalytic environment is provided for the reaction; as a main active component, potassium ions can effectively activate alpha-active methylene of ethyl acetoacetate and promote formation of negative ion intermediates; the introduction of lanthanum ions can adjust the electronic structure of the catalyst, enhance the stability of the active center and inhibit the occurrence of side reactions.

The invention discloses application of a supported heterogeneous catalyst of oxide and copper-manganese spinel in preparation of acetaldehyde by anaerobic dehydrogenation of ethanol, and belongs to the technical field of heterogeneous catalysis for preparation of acetaldehyde and hydrogen by anaerobic dehydrogenation of ethanol. The reaction is carried out in a fixed bed reactor, under the conditions that the reaction atmosphere is nitrogen, the reaction temperature is 280 DEG C and the mass space velocity is 66.1 h <-1 >, the ethanol conversion rate is 72.5%, the acetaldehyde selectivity is 95.0%, and the space time yield of acetaldehyde based on the copper-manganese composite oxide is 43.5 h <-1 >, so that high-selectivity preparation of acetaldehyde and hydrogen under relatively mild conditions is realized; the system has the remarkable advantages of simple catalyst preparation, high catalytic activity under the condition of high mass airspeed, high space-time yield of acetaldehyde, high atom utilization rate of the system, good stability and the like. The CuMnTi-1 catalyst can be stabilized for more than 70 hours, the CuMnTi-1 improves the utilization rate of copper and manganese, improves the catalytic performance, reduces the demand quantity of copper-manganese spinel in the reaction, and reduces the overall cost of catalyst preparation.

The invention discloses an industrial flue gas denitration filter bag and a preparation method thereof, and relates to the technical field of flue gas denitration. The industrial flue gas denitration filter bag comprises PTFE (Polytetrafluoroethylene) fibers, PPS (Polyphenylene Sulfide) fibers, PI (Polyimide) fibers and PTFE loaded fibers. Wherein the PTFE loaded fiber is a PTFE fiber layer loaded with a modified molecular sieve catalyst; the modified molecular sieve catalyst takes a molecular sieve coated with modified nanorods as a carrier, a vanadium-titanium composite oxide as an active catalytic component and a cerium-titanium composite oxide as a co-catalytic component; the modified nanorod is a molybdenum-tungsten composite oxide modified cerium dioxide nanorod. By introducing the modified molecular sieve catalyst prepared from cerium dioxide nanorods, lanthanum nitrate, molybdenum trioxide and other raw materials, the denitration capacity, the ammonia escape prevention capacity, the sulfur poisoning resistance, the hydrothermal stability and the working life are further improved, and an active temperature window is widened. Therefore, the method has a wider application prospect.

The invention discloses a rare-earth-based soil remediation catalyst as well as a preparation method and application thereof. The catalyst takes a composite oxide of micron-sized aluminum oxide and titanium dioxide as a carrier, a nano-fiber composite oxide of cerium oxide and copper oxide as an active component and a nano-particle composite oxide of iron oxide and manganese dioxide as a cocatalyst; on the basis of the mass of the carrier, the mass percentage of the active component is 5-10%, and the mass percentage of the cocatalyst is 3-6%. The catalyst synthesized through the method has the advantages of being good in soil compatibility, high in catalytic efficiency and the like, and the target of low-energy-consumption remediation of organic pollutant soil can be achieved.

The application belongs to the technical field of porous adsorption membrane materials, and discloses a titanium lithium ion porous adsorption membrane material and a self-assembly preparation method and application thereof. The preparation method comprises the following steps: dissolving a film-forming polymer in a dispersion liquid containing MXene nanosheets to form a uniform precursor liquid; the MXene nanosheet is a carbide, nitride or carbonitride of a transition metal with a single-layer structure; dispersing a titanium lithium composite oxide in the precursor liquid to form a casting solution; coating the casting solution on a support, and then performing phase inversion by using pure water to obtain a matrix film; placing the matrix film in a lithium elution liquid for immersion washing, replacing lithium ions in the matrix film, and causing a self-assembly reaction of the titanium lithium composite oxide in the matrix film, so that the titanium lithium ion porous adsorption membrane material is obtained. The application innovatively introduces MXene nanosheets and a polysulfone matrix film, fixes the MXene nanosheets on the polysulfone matrix film as an in-situ growth substrate of the titanium lithium composite oxide, and the obtained membrane material has a high adsorption capacity.

The invention belongs to the technical field of desulfurization gas purification, and particularly relates to a desulfurizing agent and a preparation method thereof. The desulfurizing agent is an iron-zinc-calcium composite oxide material with a hierarchical porous structure, and the preparation method of the desulfurizing agent comprises the following steps: performing amination modification on xanthan gum, then mixing the modified xanthan gum with nano cellulose, and then preparing slurry with a metal salt solution containing Fe, Zn and Ca; performing two-way temperature gradient freezing casting and freeze drying to obtain a precursor; and finally, roasting and activating under programmed temperature control. According to the preparation method, nano-scale dispersion of active components is realized by virtue of strong coordination of aminated xanthan gum and metal ions, and a high-strength and through hierarchical pore framework is constructed by virtue of nanocellulose enhancement and freezing casting. The obtained desulfurizer has ultrahigh one-time sulfur capacity, high mechanical strength and excellent structural stability, is complete in form after being used, is convenient for resource recovery, and is suitable for efficient removal of hydrogen sulfide in industrial gases such as refinery gas.

The invention provides a micron-scale high-melting-point oxide sheet layer enhanced ultra-high-temperature ceramic-based anti-ablation composite coating and a preparation method thereof.The preparation method comprises the steps that ultra-high-temperature carbide / boride ceramic powder, silicide powder and high-melting-point metal oxide powder are mechanically mixed, and spraying mixed powder with uniform components is obtained; the mixed powder is sprayed on the surface of a base body in a plasma spraying mode, and the ultra-high-temperature ceramic-based anti-ablation composite coating containing a micron-scale oxide lamellar structure is obtained; the lamellar high-melting-point oxide phase is introduced into the ultrahigh-temperature ceramic-based composite silicide coating, so that the problem that the silicon-containing glass phase is easy to lose and splash under high-heat-flow scouring is effectively solved. The high-melting-point oxide sheet layer serves as a physical barrier, can effectively limit flowing of a silicon-containing glass liquid phase in the ablation process and allows gaseous oxidation products to escape at the same time, so that a firmly-attached composite oxide layer is formed, and the oxidation resistance and the anti-scouring and anti-stripping capacity of the coating are greatly improved.

Provided is a cathode material and a preparation method therefor, and a secondary battery. The cathode material is a lithium nickel cobalt oxide composite oxide. In an XRD pattern of the cathode material, a characteristic peak of a crystal face (104) includes a (104)−Kα1 diffraction peak and a (104)−Kα2 diffraction peak after peak splitting, a separation value between the (104)−Kα1 diffraction peak and the (104)−Kα2 diffraction peak is a, and 0.7≤α≤2.0. The cathode material has suitable particle size, good particle strength and sufficient internal defects, which are conducive to reducing the phenomenon of polarization of the cathode material, such that the secondary battery based on the cathode material has both better cycle stability and rate performance.

To provide a novel positive electrode active material, a positive electrode, and a lithium ion secondary battery.SOLUTION: A lithium ion secondary battery includes a positive electrode, a negative electrode, and an electrolyte. The positive electrode includes a positive electrode active material including a complex oxide containing lithium and cobalt. The positive electrode active material contains barium, magnesium, and aluminum in a surface layer part. In the analysis of the surface layer part, it is preferable to include a region where a first point at which the concentration of barium is the maximum and a second point at which the concentration of magnesium is the maximum exist on a surface side of the positive electrode active material relative to a third point at which the concentration of aluminum is the maximum.SELECTED DRAWING: Figure 3

The invention provides iron-manganese composite oxide modified biochar (FM-SBC) as well as a preparation method and application thereof, and relates to the technical field of modified biochar. The method comprises the following steps: drying, grinding, modifying, drying and pyrolyzing excess sludge of a secondary sedimentation tank of an urban sewage treatment plant, and modifying the excess sludge by using an iron-manganese composite oxide to obtain the iron-manganese composite oxide modified biochar. The iron-manganese composite oxide modified biochar can be used as an efficient catalyst of persulfate (PS), provides technical support for treatment of refractory organic wastewater by enhancing the catalytic effect and enhancing efficient degradation of refractory organic pollutants such as azo dyes, and is of great significance to sustainable development of the environment.

The invention discloses a coal mine return air corner CO purification method based on catalytic oxidation, and relates to the technical field of coal mine return air corner CO purification, the coal mine return air corner CO purification method comprises the following steps: mixing manganese salt, cerium salt and a complexing agent by adopting a sol-gel coprecipitation method, stirring to form sol, and sequentially drying and calcining at high temperature to prepare a Mn-Ce-O composite oxide catalyst precursor; loading the Mn-Ce-O composite oxide catalyst precursor on a mesoporous carbon carrier subjected to hydrophobic modification treatment through an impregnation method, and carrying out drying and inert atmosphere heat treatment to obtain the low-temperature adaptive composite catalyst with an oxygen vacancy structure and moisture resistance, forming the low-temperature adaptive composite catalyst into a regular structure unit, filling the regular structure unit into a front end area of a reactor to form a first catalyst layer, filling a downstream area of the reactor with a thermal stability catalyst to form a second catalyst layer, and forming a catalytic reaction structure with an activity gradient along an airflow direction; the catalytic reaction structure with the activity gradient is integrated in a modular shell.

The invention relates to the technical field of catalysts, and particularly discloses a Ni-Cu-CeO2 / ZrO catalyst for improving oxidation stability of biodiesel and a preparation method of the Ni-Cu-CeO2 / ZrO catalyst. The invention discloses a Ni-Cu-CeO2 / ZrO catalyst for improving oxidation stability of biodiesel. The Ni-Cu-CeO2 / ZrO catalyst comprises a carrier, an active component and an auxiliary agent, the carrier is a CeO2-ZrO2 composite oxide; the active components are Ni and Cu; ni accounts for 3-5 wt% of the mass of the catalyst, and Cu accounts for 1-3 wt% of the mass of the catalyst; the auxiliary agent is La2O3; the preparation method comprises the following steps: firstly preparing the CeO2-ZrO2 carrier by adopting a coprecipitation method, then impregnating nickel nitrate, copper nitrate and lanthanum nitrate in an isopyknic manner, and then carrying out stepped roasting to obtain the catalyst. The catalyst has high catalytic activity and stability, unsaturated fatty acid ester in biodiesel can be removed, the oxidation stability of the biodiesel is improved, and the cost of the catalyst is lower than that of a noble metal catalyst.

This invention discloses a silver-cobalt composite oxide catalyst, its preparation method, and its application in the electrocatalytic reduction of nitrate to ammonia, relating to the field of electrochemical catalyst technology. The invention involves dissolving silver nitrate and cobalt nitrate hexahydrate in deionized water, stirring until completely dissolved, adding citric acid as a complexing agent, and continuing stirring to form a homogeneous and stable metal complex solution. The metal complex solution is continuously stirred under heating conditions to allow the solvent in the system to gradually evaporate, forming a viscous gel, which is then dried to obtain a catalyst precursor. The catalyst precursor is ground and placed in a high-temperature furnace for programmed temperature calcination in air, followed by cooling to room temperature to obtain the target catalyst. The preparation method of this invention is simple and controllable, with abundant and inexpensive raw materials, requiring no complex equipment or harsh reaction conditions, and is easy to scale up for industrial production. The obtained catalyst exhibits extremely high catalytic activity and selectivity for the electrocatalytic reduction of nitrate to ammonia, with a high ammonia yield.

Provided is a method for producing a cathode active material for a secondary battery which enables configuring a battery with improved battery resistance. The method includes providing a lithium transition metal composite powder in which a ratio of the number of moles of nickel atoms to the total number of moles of metal atoms other than lithium is 0.5 or more and less than 1 and a ratio of the number of moles of cobalt atoms to the total number of moles of metal atoms other than lithium is 0 or more and less than 0.5, the lithium transition metal composite powder having a layered structure; contacting the lithium transition metal composite powder with a cobalt raw material to obtain a cobalt-adhered composite oxide; subjecting the cobalt-adhered composite oxide to a first heat treatment performed at a temperature higher than 600° C. and lower than 800° C. to obtain a first heat-treated product; contacting the first heat-treated product with a niobium raw material to obtain a niobium-adhered composite oxide; and subjecting the niobium-adhered composite oxide to a second heat treatment performed at a temperature higher than 300° C. and lower than 500° C. to obtain a second heat-treated product.