Titanium base material, method for producing titanium base material, electrode for water electrolysis, and water electrolysis device

Abstract

This titanium base material has a base material body formed of titanium or a titanium alloy, in which a Magneli phase titanium oxide film formed of a Magneli phase titanium oxide represented by a chemical formula Ti n O 2n-1 (4≤n≤10) is formed on a surface of the base material body. Here, the Magneli phase titanium oxide film preferably contains at least one or both of Ti 4 O 7 and Ti 5 O 9 .

1 . A titanium base material comprising:
 a base material body formed of titanium or a titanium alloy,   wherein a Magneli phase titanium oxide film formed of a Magneli phase titanium oxide represented by a chemical formula Ti n O 2n-1  (4≤n≤10) is formed on a surface of the base material body.   
     
     
         2 . The titanium base material according to  claim 1 ,
 wherein the Magneli phase titanium oxide film contains at least one or both of Ti 4 O 7  and Ti 5 O 9 .   
     
     
         3 . The titanium base material according to  claim 1 ,
 wherein the Magneli phase titanium oxide film has a film thickness in a range of 0.1 μm or more and 30 μm or less.   
     
     
         4 . The titanium base material according to  claim 1 ,
 wherein the base material body is a porous body having a porosity in a range of 30% or more and 97% or less.   
     
     
         5 . The titanium base material according to  claim 1 ,
 wherein the Magneli phase titanium oxide film has a porous structure.   
     
     
         6 . A method for manufacturing the titanium base material according to  claim 1 , the method comprising:
 a TiO 2  film forming step of forming a TiO 2  film on a surface of a base material body formed of titanium or a titanium alloy; and   a reduction process step of reducing the TiO 2  film formed on the surface of the base material body by a microwave plasma reduction method to obtain a Magneli phase titanium oxide film formed of a Magneli phase titanium oxide represented by a chemical formula Ti n O 2n-1  (4≤n≤10),   wherein the reduction process step is carried out under conditions of a substrate temperature of 400° C. or lower and a process time of 15 minutes or less.   
     
     
         7 . An electrode for water electrolysis, comprising:
 the titanium base material according to  claim 1 .   
     
     
         8 . The electrode for water electrolysis according to  claim 7 ,
 wherein, in a voltammetry test in which one cycle is denoted by a holding time of 1 minute at 2.5 V and 1 minute at 0 V, an electrolysis efficiency after 1,200 cycles is 90% or more of an initial value.   
     
     
         9 . A water electrolysis device comprising:
 the electrode for water electrolysis according to  claim 7 .