JPH0327635B2 - - Google Patents
Info
- Publication number
- JPH0327635B2 JPH0327635B2 JP62068084A JP6808487A JPH0327635B2 JP H0327635 B2 JPH0327635 B2 JP H0327635B2 JP 62068084 A JP62068084 A JP 62068084A JP 6808487 A JP6808487 A JP 6808487A JP H0327635 B2 JPH0327635 B2 JP H0327635B2
- Authority
- JP
- Japan
- Prior art keywords
- iridium
- electrode
- oxide
- tantalum
- mol
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- HTXDPTMKBJXEOW-UHFFFAOYSA-N dioxoiridium Chemical compound O=[Ir]=O HTXDPTMKBJXEOW-UHFFFAOYSA-N 0.000 claims description 31
- 229910000457 iridium oxide Inorganic materials 0.000 claims description 31
- 239000000758 substrate Substances 0.000 claims description 22
- 229910052760 oxygen Inorganic materials 0.000 claims description 21
- 239000001301 oxygen Substances 0.000 claims description 21
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 19
- 229910052741 iridium Inorganic materials 0.000 claims description 17
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 claims description 17
- 229910052715 tantalum Inorganic materials 0.000 claims description 11
- BPUBBGLMJRNUCC-UHFFFAOYSA-N oxygen(2-);tantalum(5+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ta+5].[Ta+5] BPUBBGLMJRNUCC-UHFFFAOYSA-N 0.000 claims description 9
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 claims description 9
- 229910001936 tantalum oxide Inorganic materials 0.000 claims description 9
- 150000002504 iridium compounds Chemical class 0.000 claims description 8
- 230000001590 oxidative effect Effects 0.000 claims description 8
- 238000010438 heat treatment Methods 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 150000003482 tantalum compounds Chemical class 0.000 claims description 4
- 239000010410 layer Substances 0.000 description 37
- 238000005868 electrolysis reaction Methods 0.000 description 21
- 239000011248 coating agent Substances 0.000 description 19
- 238000000576 coating method Methods 0.000 description 19
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 12
- 229910052719 titanium Inorganic materials 0.000 description 12
- 239000010936 titanium Substances 0.000 description 12
- 229910052751 metal Inorganic materials 0.000 description 11
- 239000002184 metal Substances 0.000 description 11
- 239000000243 solution Substances 0.000 description 11
- 230000000694 effects Effects 0.000 description 7
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical group [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 7
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 6
- 239000011247 coating layer Substances 0.000 description 6
- 238000001035 drying Methods 0.000 description 6
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 6
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 5
- 239000002253 acid Substances 0.000 description 5
- -1 alkalis Chemical class 0.000 description 5
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- YADSGOSSYOOKMP-UHFFFAOYSA-N dioxolead Chemical compound O=[Pb]=O YADSGOSSYOOKMP-UHFFFAOYSA-N 0.000 description 4
- 150000002739 metals Chemical class 0.000 description 4
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 3
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000007664 blowing Methods 0.000 description 3
- 239000000460 chlorine Substances 0.000 description 3
- 229910052801 chlorine Inorganic materials 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 230000007797 corrosion Effects 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 238000011068 loading method Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229910052697 platinum Inorganic materials 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 238000005979 thermal decomposition reaction Methods 0.000 description 3
- 229910052725 zinc Inorganic materials 0.000 description 3
- 239000011701 zinc Substances 0.000 description 3
- 238000005246 galvanizing Methods 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- 150000002926 oxygen Chemical class 0.000 description 2
- 238000007747 plating Methods 0.000 description 2
- 229910052707 ruthenium Inorganic materials 0.000 description 2
- 229910001925 ruthenium oxide Inorganic materials 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- DJCDXWHFUVBGLR-UHFFFAOYSA-N CCO[Ta] Chemical compound CCO[Ta] DJCDXWHFUVBGLR-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- BWPVWIXXVIZIJM-UHFFFAOYSA-N [Sn]=O.[Ir]=O Chemical compound [Sn]=O.[Ir]=O BWPVWIXXVIZIJM-UHFFFAOYSA-N 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- PVZMSIQWTGPSHJ-UHFFFAOYSA-N butan-1-ol;tantalum Chemical compound [Ta].CCCCO.CCCCO.CCCCO.CCCCO.CCCCO PVZMSIQWTGPSHJ-UHFFFAOYSA-N 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 238000004210 cathodic protection Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000003631 expected effect Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- DYXZHJQUDGKPDJ-UHFFFAOYSA-N iridium;oxoplatinum Chemical compound [Ir].[Pt]=O DYXZHJQUDGKPDJ-UHFFFAOYSA-N 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 239000010955 niobium Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- SOQBVABWOPYFQZ-UHFFFAOYSA-N oxygen(2-);titanium(4+) Chemical class [O-2].[O-2].[Ti+4] SOQBVABWOPYFQZ-UHFFFAOYSA-N 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- OEIMLTQPLAGXMX-UHFFFAOYSA-I tantalum(v) chloride Chemical compound Cl[Ta](Cl)(Cl)(Cl)Cl OEIMLTQPLAGXMX-UHFFFAOYSA-I 0.000 description 1
- 229910001887 tin oxide Inorganic materials 0.000 description 1
- QHGNHLZPVBIIPX-UHFFFAOYSA-N tin(ii) oxide Chemical class [Sn]=O QHGNHLZPVBIIPX-UHFFFAOYSA-N 0.000 description 1
- DANYXEHCMQHDNX-UHFFFAOYSA-K trichloroiridium Chemical compound Cl[Ir](Cl)Cl DANYXEHCMQHDNX-UHFFFAOYSA-K 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
- C25C7/02—Electrodes; Connections thereof
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
- C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
- C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
- C25B11/091—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds
- C25B11/093—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds at least one noble metal or noble metal oxide and at least one non-noble metal oxide
Description
産業上の利用分野
本発明は新規な酸素発生用電極及びその製造方
法に関するものである。さらに詳しくいえば、本
発明は、所望の水溶液を電解して、陽極で酸素を
発生させる反応に好適に用いられる、優れた耐久
性及び低い酸素過電圧を有する酸素発生用電極及
びこれを製造するための方法に関するものであ
る。
従来の技術
従来、金属チタンを導電性基体とし、その上に
白金族金属やその酸化物の被覆層を設けた金属電
極は、種々の電解工業の分野において使用されて
いる。
例えばチタン基板上に、ルテニウムとチタンの
酸化物や、ルテニウムとスズの酸化物の被覆を施
した電極が食塩電解による塩素発生用陽極として
知られている（特公昭46−21884号公報、特公昭
48−3954号公報、特公昭50−11330号公報）。
ところで、電解工業においては、前記の食塩電
解の場合のように塩素発生を伴う電解のほかに、
酸、アルカリ又は塩の回収、銅、亜鉛などの金属
の採取、めつき、陰極防食など酸素発生を伴う場
合がある。
そして、このような酸素発生を伴う電解に、塩
素発生用として慣用されている電極、例えば前記
したチタン基板上に、ルテニウムとチタンの酸化
物やルテニウムとスズの酸化物の被覆を施した電
極を用いると、短期間で腐食し、電解が不能にな
るため、特に酸素発生用として構成された電極が
用いられている。このような電極としては、酸化
イリジウム−白金系電極、酸化イリジウム−酸化
スズ系電極、白金めつきチタン電極などが知られ
ているが、最も一般的に使用されているのは鉛系
電極や可溶性亜鉛陽極である。
しかしながら、これらの公知の電極は、その使
用目的によつては、種々のトラブルを生じ、必ず
しも適当なものとはいえない。例えば亜鉛めつき
用の陽極として可溶性亜鉛陽極を用いると、陽極
の溶解が著しいので、極間距離の調節を頻繁に行
わなければならないし、また鉛系の不溶性陽極を
用いると、電解液中に混入した鉛の影響によりめ
つき不良を生じる。また、白金めつきチタン電極
は、100A／ｄm2以上の高電流密度で、いわゆる
高速亜鉛めつきを行う場合には、消耗が激しく使
用することができない。
したがつて、酸素発生を伴う電解用として、な
んら障害を伴わずに、広い分野に普遍的に適用で
きる電極の開発が、電極製造技術における重要な
課題の１つになつている。
他方、一般に被覆層を有するチタン基板電極を
陽極として、酸素発生を伴う電解を行うと、基板
と被覆層との間に酸化チタン層を生じ、次第に陽
極電位が高くなり遂には被覆層が剥離して陽極が
不働態化することがしばしばみられ、このような
中間に形成される酸化チタンを抑制し、陽極の不
働態化を防止するために、適当な中間層を設ける
ことが行われている（特公昭60−21232号公報、
特公昭60−22074号公報、特開昭57−116786号公
報、特開昭60−184690号公報）。
しかしながら、このようにして設けられた中間
層は、一般に被覆層よりも導電性が低いため、高
電流密度で電解を行う場合には、期待するほどの
効果が得られないのが実情である。また、卑金層
酸化物に白金を分散させた中間層を設けること
（特開昭60−184691号公報）や、バルブ金属酸化
物と貴金属から成る中間層を設けること（特開昭
57−73193号公報）も提案されているが、白金は
それ自体耐食性が低いため、中間層としての効果
が不十分であるし、またバルブ金属酸化物を混合
する場合には、その種類や配合量におのずから制
約があり、所期の効果を奏することが困難であ
る。
そのほか、導電性金属基体の上に酸化イリジウ
ムと酸化タンタルを含む中間層を介して二酸化鉛
被覆を施した電極も知られているが（特開昭56−
123388号公報、特開昭56−123389号公報）、この
中間層は単に金属基体と二酸化鉛被覆との間の密
着性を改善し、ピンホールなどに起因する腐食を
防止する効果があるだけで、これを酸素発生を伴
う電解に用いた場合、酸化チタンの生成抑制の効
果が不十分な上に、電解液中に鉛が混入するのを
避けられないという欠点がある。
発明が解決しようとする問題点
本発明の目的は、チタン基板上に酸化イリジウ
ム被覆を有する電極において、中間に酸化チタン
が生成するのを効果的に抑制し、酸素発生を伴う
電解に用いた場合にも、長期間にわたつて、なん
の支障もなく使用することができ、しかも高電流
密度での電解においても低い陽極電位を示す電極
を提供することである。
問題点を解決するための手段
本発明は、優れた耐久性を有し、長期間にわた
つて使用可能な酸素発生用電極を開発するために
鋭意研究を重ねた結果、チタンのような導電性基
体と酸化イリジウム被覆層の間に、特定割合の酸
化イリジウムと酸化タンタルから成る中間層を設
けることにより、電気抵抗の増大を伴うことな
く、中間部における酸化物の生成に起因する劣化
を抑制しうることを見出し、この知見に基づいて
本発明をなすに至つた。
すなわち、本発明は、導電性基体上に、イリジ
ウム50〜90モル％及びタンタル50〜10モル％を含
有する酸化イリジウムと酸化タンタルから成る下
地層を介して、イリジウム換算で0.05〜３mg／cm2
の割合の酸化イリジウム層を設けたことを特徴と
する酸素発生用電極を提供するものである。
この酸素発生用電極は、例えば導電性基体上
に、まずイリジウム化合物とタンタル化合物とを
含有する溶液を塗布したのち、酸化性雰囲気中で
熱処理して、イリジウム50〜90モル％及びタンタ
ル50〜10モル％を含有する酸化イリジウムと酸化
タンタルとから成る下地層を形成し、次いで、こ
の上にイリジウム化合物を含有する溶液を塗布し
たのち、酸化性雰囲気中で熱処理して、0.05〜３
mg／cm2のイリジウムを含む酸化イリジウム層を施
すことによつて、製造することができる。
以下、本発明を詳細に説明する。
本発明の電極に用いられる導電性基体として
は、例えばチタン、タンタル、ジルコニウム、ニ
オブなどのバルブ金属又はこれらのバルブ金属の
中から選ばれた２種以上の金属の合金が挙げられ
る。
本発明の電極においては、これらの導電性基体
上に、下地層として酸化イリジウム及び酸化タン
タルから成る層が設けられており、この下地層中
のイリジウムとタンタルの割合は、イリジウムが
50〜90モル％及びタンタルが50〜10モル％の範囲
にあることが必要である。この範囲内において
は、酸化イリジウムの割合が少ない方が良好な電
極が得られる傾向にあるが、酸化タンタルが多す
ぎると導電性基体を保護する効果や酸化イリジウ
ム外部被覆層と導電性基体との密着強度を高める
効果が十分に発揮されない上、下地層自体の導電
性も低下する。したがつて、好ましい割合は、イ
リジウムが50〜70モル％及びタンタルが50〜30モ
ル％の範囲で選ばれる。また、該下地層は、イリ
ジウム換算で0.2mg／cm2以上の割合で施されるの
が好ましい。この量が0.2mg／cm2より少ないと下
地層としての効果が十分に発揮されない。
本発明の電極においては、前記下地層の上に、
酸化イリジウム層が設けられるが、この酸化イリ
ジウム層は、イリジウム換算0.05〜３mg／cm2の割
合で施すことが必要である。この酸化イリジウム
の担持量が、イリジウム換算0.05mg／cm2未満では
電解時の電極消耗量が多く、耐久性が低下する
し、また３mg／cm2を超えると電極活性膜の密着強
度が低下し、かつ短時間で電解時の陽極電位が上
昇する。
次に、この酸素発生用電極を製造するための好
適な実施態様を説明すると、まず導電性基体上
に、イリジウム化合物とタンタル化合物とを含有
する溶液を塗布したのち、酸化性雰囲気中で熱処
理して、イリジウム50〜90モル％及びタンタル50
〜10モル％を含有する下地層を設ける。この際使
用する塗布液は、熱分解によつて酸化イリジウム
になる化合物、例えば塩化イリジウム酸
（H2IrCl6・6H2O）などのイリジウム化合物と、
熱分解によつて酸化タンタルになる化合物、例え
ば塩化タンタルのようなハロゲン化タンタルやエ
トキシタンタルのようなタンタルアルコキシドな
どのタンタル化合物とを、所定の割合で適当な溶
媒に溶解することによつて調製することができ
る。また、酸化性雰囲気中での熱処理は、前記塗
布液を導電性基体上に塗布し、乾燥したのち、酸
素の存在下に、好ましくは400〜550℃の範囲の温
度において焼成することによつて行われる。この
操作は、必要な担持量になるまで複数回繰り返さ
れる。
このようにして、所望の担持量の下地層が得ら
れるが、本発明においては、さらに、この上に、
イリジウム化合物を含有する溶液を塗布したの
ち、酸化性雰囲気中で熱処理することにより、
0.05〜３mg／cm2のイリジウム量に相当する量の酸
化イリジウム層が施される。この際用いられるイ
リジウム化合物を含有する溶液は、熱分解によつ
て酸化イリジウムになる化合物、例えば塩化イリ
ジウム酸（H2IrCl6・6H2O）などのイリジウム化
合物を、適当な溶媒に溶解することによつて調製
することができる。また、酸化性雰囲気中での熱
処理は、この塗布液を該下地層の上に塗布し、乾
燥したのち、酸素の存在下、好ましくは450〜550
℃の範囲の温度において、焼成することによつて
行われる。この操作は必要な担持量に達するまで
複数回繰り返される。このようにして、該下地層
の上に、所望の担持量を有する酸化イリジウム層
が施され、本発明の電極が得られる。下地層及び
酸化イリジウム層を形成するための熱処理を酸化
雰囲気中で行わない場合には、酸化が不十分にな
り、金属が遊離状態で存在するので得られる電極
の耐久性が低下する。
発明の効果
本発明の電極は、酸素発生を伴う電解において
陽極として使用する場合、低い槽電圧で長期間の
使用に耐える上、100A／ｄm2以上の高電流密度
で電解を行つても、耐食性に優れ、長期間の使用
が可能である。
このように、本発明の電極は、素発生用電極と
して、好適である。
実施例
次に実施例により本発明をさらに詳細に説明す
るが、本発明はこれらの例によつてなんら限定さ
れるものではない。
実施例 １
イリジウム60モル％、タンタル40モル％の組成
になるように、塩化イリジウム酸（H2IrCl6・
6H2O）およびタンタルブトキシド（Ta
（OC4H9）5）をブタノールに溶解して、金属換算
濃度80ｇ／の下地用塗布液を調製した。
酸化イリジウム上層被覆用の塗布液として、イ
リジウム金属60ｇ／の濃度になるように、塩化
イリジウム酸をブタノールに溶解し調製した。
別に、熱シユウ酸でエツチングしたチタン基体
上に、前記下地用塗布液をフデで塗布し、乾燥し
た後、電気炉に入れて空気を吹き込みながら450
℃で焼付けた。この塗布、乾燥、焼付けの操作を
適当な回数繰り返して、下地層の担持量を変化さ
せた試料を作製した。
次に、該下地層を設けた試料の上に、前記酸化
イリジウム上層被覆用の塗布液をフデで塗布し、
乾燥した後、電気炉に入れて空気を吹き込みなが
ら450℃で焼付けた。この塗布、乾燥、焼付けの
操作を繰り返して、下地層の上に酸化イリジウム
上層を被覆した本発明の電極を作製した。
この際の各試料についての塗布、焼付け回数を
第１表に示す。なお、比較のために酸化イリジウ
ム層のみを被覆した試料（No.１）及び下地層のみ
を被覆した試料（No.６）も同様にして作製した。
INDUSTRIAL APPLICATION FIELD The present invention relates to a novel oxygen generating electrode and its manufacturing method. More specifically, the present invention provides an electrode for oxygen generation having excellent durability and low oxygen overvoltage, which is suitably used in a reaction in which a desired aqueous solution is electrolyzed to generate oxygen at an anode, and a method for producing the same. This relates to the method of BACKGROUND ART Conventionally, metal electrodes having a conductive substrate made of titanium and a coating layer of a platinum group metal or its oxide have been used in various fields of electrolysis industry. For example, an electrode made of a titanium substrate coated with oxides of ruthenium and titanium or oxides of ruthenium and tin is known as an anode for chlorine generation by salt electrolysis (Japanese Patent Publication No. 46-21884,
48-3954, Special Publication No. 11330/1983). By the way, in the electrolysis industry, in addition to electrolysis that involves chlorine generation, as in the case of salt electrolysis,
Oxygen generation may be involved in recovery of acids, alkalis, or salts, extraction of metals such as copper and zinc, plating, and cathodic protection. For such electrolysis involving oxygen generation, an electrode commonly used for chlorine generation, such as an electrode coated with ruthenium and titanium oxides or ruthenium and tin oxides on the titanium substrate described above, is used. If used, it will corrode in a short period of time, making electrolysis impossible, so electrodes specifically designed for oxygen generation are used. Known examples of such electrodes include iridium oxide-platinum electrodes, iridium oxide-tin oxide electrodes, and platinum-plated titanium electrodes, but the most commonly used electrodes are lead-based electrodes and soluble Zinc anode. However, these known electrodes cause various problems and are not necessarily suitable depending on the purpose of use. For example, if a soluble zinc anode is used as an anode for galvanizing, the anode will dissolve significantly, so the distance between the electrodes must be adjusted frequently, and if a lead-based insoluble anode is used, Plating defects occur due to the influence of mixed lead. Further, platinum-plated titanium electrodes are severely worn out and cannot be used when performing so-called high-speed galvanizing at a high current density of 100 A/dm 2 or more. Therefore, one of the important issues in electrode manufacturing technology is the development of electrodes that can be universally applied to a wide range of fields without any problems for electrolysis involving oxygen generation. On the other hand, when electrolysis accompanied by oxygen generation is generally performed using a titanium substrate electrode with a coating layer as an anode, a titanium oxide layer is generated between the substrate and the coating layer, and the anode potential gradually increases, eventually causing the coating layer to peel off. It is often seen that the anode becomes passivated during the process, and in order to suppress the titanium oxide formed in the intermediate layer and prevent the anode from becoming passivated, an appropriate intermediate layer is provided. (Special Publication No. 60-21232,
Japanese Patent Publication No. 60-22074, Japanese Patent Application Publication No. 57-116786, Japanese Patent Application Publication No. 60-184690). However, since the intermediate layer provided in this manner generally has lower conductivity than the covering layer, the actual situation is that when electrolysis is performed at a high current density, the expected effect cannot be obtained. Furthermore, it is also possible to provide an intermediate layer in which platinum is dispersed in a base gold layer oxide (Japanese Patent Application Laid-Open No. 60-184691), or to provide an intermediate layer made of a valve metal oxide and a noble metal (Japanese Patent Application Laid-Open No. 184691).
57-73193) has also been proposed, but since platinum itself has low corrosion resistance, it is insufficiently effective as an intermediate layer, and when a valve metal oxide is mixed, its type and composition must be adjusted. There are natural restrictions on the amount, making it difficult to achieve the desired effect. In addition, an electrode is known in which a conductive metal substrate is coated with lead dioxide through an intermediate layer containing iridium oxide and tantalum oxide (Japanese Patent Laid-Open Publication No. 1983-1999).
(No. 123388, Japanese Unexamined Patent Publication No. 123389/1983), this intermediate layer merely improves the adhesion between the metal substrate and the lead dioxide coating, and has the effect of preventing corrosion caused by pinholes, etc. When this is used in electrolysis involving oxygen generation, there are disadvantages in that not only the effect of suppressing the production of titanium oxide is insufficient, but also lead cannot be avoided from being mixed into the electrolyte. Problems to be Solved by the Invention The purpose of the present invention is to effectively suppress the formation of titanium oxide in the middle of an electrode having an iridium oxide coating on a titanium substrate, and to effectively suppress the formation of titanium oxide in an electrode having an iridium oxide coating on a titanium substrate. Another object of the present invention is to provide an electrode that can be used for a long period of time without any problems and exhibits a low anodic potential even in electrolysis at high current density. Means for Solving the Problems The present invention was developed as a result of intensive research to develop an electrode for oxygen generation that has excellent durability and can be used for a long period of time. By providing an intermediate layer consisting of a specific proportion of iridium oxide and tantalum oxide between the substrate and the iridium oxide coating layer, deterioration caused by the formation of oxides in the intermediate region can be suppressed without increasing electrical resistance. Based on this knowledge, the present invention was completed. That is, in the present invention, 0.05 to 3 mg/cm 2 in terms of iridium is formed on a conductive substrate through an underlayer consisting of iridium oxide and tantalum oxide containing 50 to 90 mol% of iridium and 50 to 10 mol% of tantalum.
The present invention provides an electrode for oxygen generation characterized by providing an iridium oxide layer with a ratio of . This oxygen generating electrode can be made by first applying a solution containing an iridium compound and a tantalum compound onto a conductive substrate, and then heat-treating it in an oxidizing atmosphere to produce a solution containing 50 to 90 mol% iridium and 50 to 10 mol% tantalum. A base layer made of iridium oxide and tantalum oxide containing mol% of
It can be produced by applying an iridium oxide layer containing mg/cm 2 of iridium. The present invention will be explained in detail below. Examples of the conductive substrate used in the electrode of the present invention include valve metals such as titanium, tantalum, zirconium, and niobium, or alloys of two or more metals selected from these valve metals. In the electrode of the present invention, a layer consisting of iridium oxide and tantalum oxide is provided as a base layer on these conductive substrates, and the ratio of iridium to tantalum in this base layer is such that iridium is
50-90 mol% and tantalum in the range 50-10 mol%. Within this range, the smaller the proportion of iridium oxide, the better the electrode tends to be obtained, but if the proportion of tantalum oxide is too large, the effect of protecting the conductive substrate and the interference between the iridium oxide outer coating layer and the conductive substrate Not only is the effect of increasing adhesion strength not sufficiently exhibited, but also the conductivity of the underlayer itself is reduced. Therefore, preferred proportions are selected in the range of 50-70 mol% iridium and 50-30 mol% tantalum. Further, the underlayer is preferably applied at a rate of 0.2 mg/cm 2 or more in terms of iridium. If this amount is less than 0.2 mg/cm 2 , the effect as a base layer will not be sufficiently exhibited. In the electrode of the present invention, on the base layer,
An iridium oxide layer is provided, and this iridium oxide layer needs to be applied at a rate of 0.05 to 3 mg/cm 2 in terms of iridium. If the amount of iridium oxide supported is less than 0.05 mg/cm 2 in terms of iridium, the amount of electrode consumption during electrolysis will be large and the durability will decrease, and if it exceeds 3 mg/cm 2 , the adhesion strength of the electrode active film will decrease. , and the anode potential during electrolysis increases in a short time. Next, to explain a preferred embodiment for manufacturing this oxygen generating electrode, first, a solution containing an iridium compound and a tantalum compound is applied onto a conductive substrate, and then heat-treated in an oxidizing atmosphere. 50-90 mol% iridium and 50% tantalum
Provide an underlayer containing ~10 mol%. The coating liquid used at this time is a compound that becomes iridium oxide through thermal decomposition, such as an iridium compound such as chloroiridic acid (H 2 IrCl 6 6H 2 O),
Prepared by dissolving a compound that becomes tantalum oxide through thermal decomposition, such as a tantalum compound such as a tantalum halide such as tantalum chloride or a tantalum alkoxide such as ethoxytantalum, in an appropriate solvent in a predetermined ratio. can do. The heat treatment in an oxidizing atmosphere can be carried out by applying the coating solution onto the conductive substrate, drying it, and then baking it in the presence of oxygen, preferably at a temperature in the range of 400 to 550°C. It will be done. This operation is repeated multiple times until the required amount of loading is achieved. In this way, a desired supporting amount of the underlayer is obtained, but in the present invention, on top of this,
After applying a solution containing an iridium compound, heat treatment is performed in an oxidizing atmosphere.
An iridium oxide layer is applied in an amount corresponding to an iridium amount of 0.05 to 3 mg/cm 2 . The solution containing the iridium compound used at this time is a compound that becomes iridium oxide through thermal decomposition, such as an iridium compound such as chloroiridic acid (H 2 IrCl 6 6H 2 O), which is dissolved in an appropriate solvent. It can be prepared by In addition, heat treatment in an oxidizing atmosphere is performed by coating this coating solution on the base layer, drying it, and then applying heat treatment at a temperature of preferably 450 to 550 in the presence of oxygen.
This is done by calcination at a temperature in the range of °C. This operation is repeated multiple times until the required amount of loading is reached. In this way, an iridium oxide layer having a desired loading amount is applied on the underlayer to obtain the electrode of the present invention. If the heat treatment for forming the underlayer and iridium oxide layer is not performed in an oxidizing atmosphere, the oxidation will be insufficient and the metal will exist in a free state, resulting in reduced durability of the resulting electrode. Effects of the Invention When the electrode of the present invention is used as an anode in electrolysis involving oxygen generation, it can withstand long-term use at a low cell voltage and is corrosion resistant even when electrolyzed at a high current density of 100 A/dm 2 or more. It has excellent properties and can be used for a long period of time. Thus, the electrode of the present invention is suitable as an electrode for element generation. Examples Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way. Example 1 Iridium chloride (H 2 IrCl 6 .
6H 2 O) and tantalum butoxide (Ta
(OC 4 H 9 ) 5 ) was dissolved in butanol to prepare a base coating solution with a concentration of 80 g/metal equivalent. A coating solution for coating the iridium oxide upper layer was prepared by dissolving chloroiridic acid in butanol to give a concentration of 60 g/iridium metal. Separately, on a titanium substrate etched with hot oxalic acid, the base coating solution was applied with a spade, dried, and then placed in an electric furnace and heated for 450 minutes while blowing air.
Baked at ℃. These coating, drying, and baking operations were repeated an appropriate number of times to prepare samples with varying amounts of the underlying layer supported. Next, on the sample provided with the base layer, apply the coating liquid for coating the iridium oxide upper layer with a spade,
After drying, it was placed in an electric furnace and baked at 450°C while blowing air. The coating, drying, and baking operations were repeated to produce an electrode of the present invention in which the underlayer was coated with an iridium oxide upper layer. Table 1 shows the number of times of coating and baking for each sample. For comparison, a sample coated with only the iridium oxide layer (No. 1) and a sample coated with only the base layer (No. 6) were also prepared in the same manner.
【表】
次に、60℃、１モル／硫酸水溶液中で、陰極
に白金を用い、電流密度150A／ｄm2で、前記No.
１〜No.６の６点の電極を陽極として電解を行つ
た。この際の経時的な槽電圧の変化をグラフとし
て図面に示す。
この図から明らかなように、下地層のみを被覆
した電極（No.６）と、酸化イリジウムのみを被覆
した電極（No.１）は、約1500時間の電解で槽電圧
が10Vに達し、電解不能となつたにもかかわら
ず、本発明の電極（No.２〜No.５）は、約3000時間
以上も、低い槽電圧を維持したまま電解可能であ
つた。
実施例 ２
Ir／Ta組成比を変化させた下地用塗布液を調
製してエツチング処理済のチタン基体上に塗布
し、乾燥した後、電気炉に入れて空気を吹き込み
ながら500℃で焼き付けた。この塗布、乾燥、焼
付けの操作を５回繰返し、Ir／Ta組成比を変化
させた下地層を持つ試料を作製した。
該下地層を設けた試料の上に、塩化イリジウム
酸をブタノールに溶解した酸化イリジウム上層被
覆用の塗布液を塗布し、乾燥した後、500℃で焼
き付けた。この操作を５回繰り返し、No.７〜No.11
の電極を作製した。
次に、60℃、１モル／硫酸水溶液中で、陰極
に白金を用い、電流密度200A／ｄm2で、前記No.
７〜No.11の５点の電極を陽極として電解を行い、
電解が使用不能となるまでの電解時間（電極寿命
と表現する）を求めた。その結果を第２表に示
す。
なお、No.７及びNo.８は比較例である。[Table] Next, the above - mentioned No.
Electrolysis was performed using six electrodes No. 1 to No. 6 as anodes. The change in cell voltage over time at this time is shown in the drawing as a graph. As is clear from this figure, the electrode covered only with the base layer (No. 6) and the electrode covered only with iridium oxide (No. 1) reached a cell voltage of 10 V after about 1500 hours of electrolysis, and Despite this failure, the electrodes of the present invention (No. 2 to No. 5) were able to perform electrolysis while maintaining a low cell voltage for about 3000 hours or more. Example 2 Base coating liquids with varying Ir/Ta composition ratios were prepared and applied onto etched titanium substrates, dried, and then placed in an electric furnace and baked at 500°C while blowing air. These coating, drying, and baking operations were repeated five times to produce samples with base layers with varying Ir/Ta composition ratios. On top of the sample provided with the base layer, a coating solution for covering the iridium oxide upper layer, which was prepared by dissolving chloroiridic acid in butanol, was applied, dried, and then baked at 500°C. Repeat this operation 5 times, No. 7 to No. 11
An electrode was fabricated. Next, at 60°C, in a 1 mol/sulfuric acid aqueous solution, using platinum as the cathode, and at a current density of 200 A/dm 2 , the above No.
Electrolysis is performed using the five electrodes No. 7 to No. 11 as anodes,
The electrolysis time (expressed as electrode life) until electrolysis became unusable was determined. The results are shown in Table 2. Note that No. 7 and No. 8 are comparative examples.
【表】
この表から明らかなように、本発明の電極は比
較例のものに比べ電極寿命が著しく長くなつてい
る。
参考例
実施例１で作製したNo.１〜No.５の電極につい
て、その酸素過電圧を測定した。測定は、電位走
査法により、30℃、１モル／硫酸水溶液中で電
流密度20A／ｄm2における値を求めた。その結果
を第３表に示す。[Table] As is clear from this table, the electrode of the present invention has a significantly longer electrode life than that of the comparative example. Reference Example The oxygen overvoltage of electrodes No. 1 to No. 5 produced in Example 1 was measured. The measurement was carried out by a potential scanning method, at 30° C., in a 1 mol/sulfuric acid aqueous solution at a current density of 20 A/dm 2 . The results are shown in Table 3.
【表】
この表から明らかなように、本発明の電極（No.
２〜No.５）は、酸化イリジウムのみを被覆した電
極（No.１）よりも低い酸素過電圧を有する。[Table] As is clear from this table, the electrode of the present invention (No.
2 to No. 5) have a lower oxygen overpotential than the electrode coated only with iridium oxide (No. 1).
図面は、本発明の実施例及び比較例の電極の経
時的な槽電圧の変化を示すグラフである。
The drawing is a graph showing changes in cell voltage over time of electrodes of Examples of the present invention and Comparative Examples.
Claims (1)
びタンタル50〜10モル％を含有する酸化イリジウ
ムと酸化タンタルとから成る下地層を介して、イ
リジウム換算で0.05〜３mg／cm2の割合の酸化イリ
ジウム層を設けたことを特徴とする酸素発生用電
極。 ２ 導電性基体上に、まずイリジウム化合物とタ
ンタル化合物とを含有する溶液を塗布後、酸化性
雰囲気中で熱処理して、イリジウム50〜90モル％
及びタンタル50〜10モル％を含有する酸化イリジ
ウムと酸化タンタルとから成る下地層を形成さ
せ、次いで、この上にイリジウム化合物を含有す
る溶液を塗布後酸化性雰囲気中で熱処理して、
0.05〜３mg／cm2のイリジウムを含む酸化イリジウ
ム層を形成させることを特徴とする酸素発生用電
極の製造方法。[Scope of Claims] 1. 0.05 to 3 mg/in terms of iridium is applied on a conductive substrate via a base layer consisting of iridium oxide and tantalum oxide containing 50 to 90 mol% of iridium and 50 to 10 mol% of tantalum. An electrode for oxygen generation characterized by providing an iridium oxide layer with a ratio of cm2 . 2. First, a solution containing an iridium compound and a tantalum compound is applied onto a conductive substrate, and then heat-treated in an oxidizing atmosphere to add 50 to 90 mol% of iridium.
A base layer made of iridium oxide and tantalum oxide containing 50 to 10 mol% of tantalum is formed, and then a solution containing an iridium compound is applied thereon, followed by heat treatment in an oxidizing atmosphere.
A method for producing an electrode for oxygen generation, comprising forming an iridium oxide layer containing 0.05 to 3 mg/cm 2 of iridium.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62068084A JPS63235493A (en) | 1987-03-24 | 1987-03-24 | Electrode for generating oxygen and production thereof |
| CA000576559A CA1327339C (en) | 1987-03-24 | 1988-09-06 | Oxygen-generating electrode and method for the preparation thereof |
| EP88308703A EP0359876B1 (en) | 1987-03-24 | 1988-09-20 | Oxygen-generating electrode and method for the preparation thereof |
| US07/581,417 US5156726A (en) | 1987-03-24 | 1990-09-12 | Oxygen-generating electrode and method for the preparation thereof |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62068084A JPS63235493A (en) | 1987-03-24 | 1987-03-24 | Electrode for generating oxygen and production thereof |
| CA000576559A CA1327339C (en) | 1987-03-24 | 1988-09-06 | Oxygen-generating electrode and method for the preparation thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63235493A JPS63235493A (en) | 1988-09-30 |
| JPH0327635B2 true JPH0327635B2 (en) | 1991-04-16 |
Family
ID=27426573
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62068084A Granted JPS63235493A (en) | 1987-03-24 | 1987-03-24 | Electrode for generating oxygen and production thereof |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0359876B1 (en) |
| JP (1) | JPS63235493A (en) |
| CA (1) | CA1327339C (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2616024B2 (en) * | 1989-07-14 | 1997-06-04 | 日本鋼管株式会社 | Manufacturing method of electro-galvanized steel sheet with low degree of electrode damage |
| JP2713788B2 (en) * | 1989-12-22 | 1998-02-16 | ティーディーケイ株式会社 | Oxygen generating electrode and method for producing the same |
| JPH0499294A (en) * | 1990-08-09 | 1992-03-31 | Daiso Co Ltd | Oxygen generating anode and its production |
| KR100196094B1 (en) * | 1992-03-11 | 1999-06-15 | 사토 히로시 | Oxygen generating electrode |
| EP0867527B1 (en) * | 1997-02-27 | 2001-03-21 | Aragonesas Industrias Y Energia, S.A. | Electrode with catalytic coating for electrochemical processes and manufacture thereof |
| US6217729B1 (en) * | 1999-04-08 | 2001-04-17 | United States Filter Corporation | Anode formulation and methods of manufacture |
| KR102305334B1 (en) * | 2019-10-04 | 2021-09-28 | 주식회사 웨스코일렉트로드 | A method for manufacturing anode plate |
| CN114272920B (en) * | 2021-11-22 | 2023-10-03 | 广东省科学院资源利用与稀土开发研究所 | Composite oxide coating electrode for degrading organic pollutants and preparation method thereof |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6021232B2 (en) * | 1981-05-19 | 1985-05-25 | ペルメレツク電極株式会社 | Durable electrolytic electrode and its manufacturing method |
| JPS6022075B2 (en) * | 1983-01-31 | 1985-05-30 | ペルメレック電極株式会社 | Durable electrolytic electrode and its manufacturing method |
| EP0243302B1 (en) * | 1986-04-17 | 1992-01-22 | Eltech Systems Corporation | An electrode with a platinum metal catalyst in surface film and its use |
-
1987
- 1987-03-24 JP JP62068084A patent/JPS63235493A/en active Granted
-
1988
- 1988-09-06 CA CA000576559A patent/CA1327339C/en not_active Expired - Fee Related
- 1988-09-20 EP EP88308703A patent/EP0359876B1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CA1327339C (en) | 1994-03-01 |
| EP0359876B1 (en) | 1992-06-17 |
| EP0359876A1 (en) | 1990-03-28 |
| JPS63235493A (en) | 1988-09-30 |
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