# US 12,758,956 B2 · Semiconductor particles used in water decomposition photocatalyst, photocatalyst using the same, and methods of synthesizing them > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,758,956 B2 - Document ID: US12758956B2 - Status: Granted - Kind: B2 - Application number: 18/464,267 - Filed: 2023-09-11 - Published: 2024-03-21 - Granted: 2026-10-13 - Earliest claimed: 2022-09-15 - Assignees: Toyota Jidosha Kabushiki Kaisha; Konan Gakuen; Toyoda Gosei Co., Ltd. - Applicants: Toyota Jidosha Kabushiki Kaisha; Konan Gakuen; Toyoda Gosei Co., Ltd. - Inventors: Taizo Masuda; Ryota Tomizawa; Kenichi Okumura; Tatsuya Hasegawa; Shigeru Ikeda - Web page: https://patentgrep.com/patent/US12758956B2 ## CPC - B01J 35/39: Photocatalytic properties - B01J 23/02: of the alkali- or alkaline earth metals or beryllium - B01J 23/6522: {Chromium} - B01J 23/75: Cobalt - B01J 37/0221: {of particles} - B01J 37/04: Mixing {(B01J37/0009, B01J37/0018 take precedence)} - B01J 37/08: Heat treatment {(B01J37/0009, B01J37/0018 take precedence)} - C01B 3/042: Decomposition of water (by electrolysis of water C25B1/04) - C01B 13/0207: {Water} - B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS - C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C} ## Abstract In a photocatalyst which is obtained by adding a co-catalyst to semiconductor particles containing strontium titanate and which causes a water decomposition reaction in which water molecules are decomposed into oxygen molecules and hydrogen molecules according to light emission, the semiconductor particles are doped with barium or additionally with scandium. A method of synthesizing a semiconductor for the photocatalyst includes a process of synthesizing semiconductor particles containing strontium titanate doped with barium by mixing barium titanate or additionally with scandium oxide into strontium chloride or mixing strontium titanate or additionally scandium oxide into strontium chloride and barium chloride and performing firing. ## Claims ### Claim 1 Semiconductor particles containing strontium titanate used as a photocatalyst that causes a water decomposition reaction in which water molecules are decomposed into oxygen molecules and hydrogen molecules according to light emission, and in which strontium titanate is doped with barium, wherein the strontium titanate is additionally doped with scandium. ### Claim 2 (depends on 1) The semiconductor particles according to claim 1, wherein the content of barium is 0.04 parts by weight to 5 parts by weight, and the content of scandium is 0.1 parts by weight to 1 part by weight with respect to 100 parts by weight of strontium titanate. ### Claim 3 (depends on 2) The semiconductor particles according to claim 2, wherein the content of barium is 0.1 parts by weight to 2 parts by weight. ### Claim 4 (depends on 1) The semiconductor particles according to claim 1, which are substantially free of aluminum. ### Claim 5 (depends on 4) The semiconductor particles according to claim 4, wherein the content of aluminum with respect to 100 parts by weight of strontium titanate is 1 part by weight or less. ### Claim 6 (depends on 5) A photocatalyst obtained by adding a co-catalyst to the semiconductor particles according to claim 5, wherein the co-catalyst is rhodium-chromium oxide (Rh/Cr2O3) or cobalt hydroxide oxide (CoOOH). ### Claim 7 (depends on 4) A photocatalyst obtained by adding a co-catalyst to the semiconductor particles according to claim 4, wherein the co-catalyst is rhodium-chromium oxide (Rh/Cr2O3) or cobalt hydroxide oxide (CoOOH). ### Claim 8 (depends on 1) A photocatalyst obtained by adding a co-catalyst to the semiconductor particles according to claim 1, wherein the co-catalyst is rhodium-chromium oxide (Rh/Cr2O3) or cobalt hydroxide oxide (CoOOH). ### Claim 9 (depends on 8) The photocatalyst according to claim 8, wherein the co-catalyst is added to the surface of the semiconductor particles dispersed in water by photoelectrodepositing. ### Claim 10 A method of synthesizing semiconductor particles used in a photocatalyst which is obtained by adding a co-catalyst to semiconductor particles containing strontium titanate and which causes a water decomposition reaction in which water molecules are decomposed into oxygen molecules and hydrogen molecules according to light emission, the method comprising a process of synthesizing the semiconductor particles containing strontium titanate doped with barium by mixing barium titanate (BaTiO3) into strontium chloride (SrCl2) and performing firing. ### Claim 11 (depends on 10) The method according to claim 10, wherein, in the process of synthesizing the semiconductor particles, the semiconductor particles are doped with barium and scandium by additionally mixing scandium oxide (Sc2O3) into the strontium chloride and performing firing. ### Claim 12 (depends on 11) The method according to claim 11, wherein, in the process of synthesizing the semiconductor particles, 500 parts by mole to 2,000 parts by mole of strontium chloride and 0.1 parts by mole to 5 parts by mole of scandium oxide with respect to 100 parts by mole of barium titanate are mixed in and fired to synthesize the semiconductor particles. ### Claim 13 (depends on 10) The method according to claim 10, wherein, in the process of synthesizing semiconductor particles, a firing temperature is 1,000° C. to 1,200° C., and a firing time is 10 hours to 30 hours. ### Claim 14 (depends on 10) A method of synthesizing a photocatalyst that causes a water decomposition reaction in which water molecules are decomposed into oxygen molecules and hydrogen molecules according to light emission using the semiconductor particles synthesized by the method according to claim 10, the method comprising a process of adding the co-catalyst to the surface of the semiconductor particles dispersed in water. ### Claim 15 (depends on 14) The method according to claim 14, wherein the co-catalyst is rhodium-chromium oxide (Rh/Cr2O3) or cobalt hydroxide oxide (CoOOH). ### Claim 16 (depends on 15) The method according to claim 15, wherein, in the process of adding the co-catalyst, the co-catalyst is added to the surface of the semiconductor particles dispersed in water by photoelectrodepositing. ### Claim 17 A method of synthesizing semiconductor particles used in a photocatalyst which is obtained by adding a co-catalyst to semiconductor particles containing strontium titanate and which causes a water decomposition reaction in which water molecules are decomposed into oxygen molecules and hydrogen molecules according to light emission, the method comprising a process of synthesizing the semiconductor particles containing strontium titanate doped with barium and scandium by mixing strontium titanate (SrTiO3) and scandium oxide (Sc2O3) into a mixture containing strontium chloride (SrCl2) and barium chloride (BaCl2) and performing firing. ### Claim 18 (depends on 17) The method according to claim 17, wherein, in the process of synthesizing the semiconductor particles, the semiconductor particles are additionally doped with aluminum by additionally mixing aluminum oxide (Al2O3) into the mixture containing strontium chloride and barium chloride and performing firing. ### Claim 19 (depends on 17) The method according to claim 17, wherein, in the process of synthesizing the semiconductor particles, the semiconductor particles are synthesized by mixing a mixture containing strontium chloride and barium chloride at a molar ratio of 1:9 to 9:1 as a mixture of 1,000 parts by mole of strontium chloride and barium chloride with respect to 100 parts by mole of strontium titanate, 0.1 parts by mole to 5 parts by mole of scandium oxide (Sc2O3) and 0 parts by mole to 5 parts by mole of aluminum oxide and performing firing.