Bismuth metal oxide pyrochlores as electrode materials for electrolytic ozone and perchlorate generation

Abstract

Novel bismuth based mixed metal oxide materials with pyrochlore structure are disclosed as anodes for electrolytic generation of ozone and perchlorate salts. These materials have high electrical conductivity and excellent stability in acidic electrolytes. These materials are more environmentally friendly than lead dioxide and less expensive than platinum.

1 . An electrolytic method of generating ozone comprising:
 providing an electrolytic cell having an anode comprising a bismuth mixed metal oxide pyrochlore material having the general formula A 2 B 2 O 7-x , where A is Bi and B is Ru, Ir, Rh, Sn, Ti, or Pt, and 0≦x≦1; and   operating the electrolytic cell anode at a current density sufficient to generate ozone.   
     
     
         2 . The method of  claim 1 , wherein the generation of ozone is accomplished according to the reaction: 3H 2 O→O 3 +6H + +6e − . 
     
     
         3 . The method of  claim 1 , wherein the electrolytic cell anode is operated at a current density greater than about 1 A/cm 2 . 
     
     
         4 . The method of  claim 1 , wherein the electrolytic cell anode is operated at a current density greater than about 1.2 A/cm 2 . 
     
     
         5 . The method of  claim 1 , wherein the electrolytic cell anode is operated at a current density greater than about 1.4 A/cm 2 . 
     
     
         6 . The method of  claim 1 , wherein the electrolytic cell anode is operated at a current density of approximately 1.5 A/cm 2 . 
     
     
         7 . The method of  claim 1 , wherein B is Ru. 
     
     
         8 . The method of  claim 1 , wherein the electrolytic cell has a cathode comprising the bismuth mixed metal oxide pyrochlore material. 
     
     
         9 . The method of  claim 1 , wherein the anode comprises a composite of the bismuth mixed metal oxide pyrochlore material and one or more noble metals selected from Pt, Ag, Au, Ru, Re, and Pd. 
     
     
         10 . An electrolytic cell for generating ozone comprising:
 an anode comprising a bismuth mixed metal oxide pyrochlore material having the general formula A 2 B 2 O 7-x , where A is Bi and B is Ru, Ir, Rh, Sn, Ti, or Pt, and 0≦x≦1;   a cathode;   electrolyzable water in contact with the anode and the cathode; and   a source of electric potential and current electrically coupled to the anode and the cathode to produce an operating current density sufficient to generate ozone at the anode.   
     
     
         11 . The method of  claim 1 , wherein the generation of ozone is accomplished according to the reaction: 3H 2 O→O 3 +6H + +6e − . 
     
     
         12 . The electrolytic cell of  claim 10 , wherein the electrolytic cell anode is operated at a current density greater than about 1 A/cm 2 . 
     
     
         13 . The electrolytic cell of  claim 10 , wherein the electrolytic cell anode is operated at a current density greater than about 1.2 A/cm 2 . 
     
     
         14 . The electrolytic cell of  claim 10 , wherein the electrolytic cell anode is operated at a current density greater than about 1.4 A/cm 2 . 
     
     
         15 . The electrolytic cell of  claim 10 , wherein the electrolytic cell anode is operated at a current density of approximately 1.5 A/cm 2 . 
     
     
         16 . The electrolytic cell of  claim 10 , wherein B is Ru. 
     
     
         17 . The electrolytic cell of  claim 10 , wherein the electrolytic cell has a cathode comprising the bismuth mixed metal oxide pyrochlore material. 
     
     
         18 . The electrolytic cell of  claim 10 , wherein the anode comprises a composite of the bismuth mixed metal oxide pyrochlore material and one or more noble metals selected from Pt, Ag, Au, Ru, Re, and Pd. 
     
     
         19 . An electrolytic method of generating a perchlorate salt comprising:
 providing an electrolytic cell having an anode comprising a bismuth mixed metal oxide pyrochlore material having the general formula A 2 B 2 O 7-x , where A is Bi and B is Ru, Ir, Rh, Sn, Ti, or Pt, and 0≦x≦1; and   operating the electrolytic cell anode at a current density sufficient to oxidize a chlorate salt in aqueous solution to form a perchlorate salt in aqueous solution.   
     
     
         20 . The method of  claim 19 , wherein the electrolytic cell anode is operated at a current density greater than about 1 A/cm 2 . 
     
     
         21 . The method of  claim 19 , wherein B is Ru. 
     
     
         22 . The method of  claim 19 , wherein the electrolytic cell has a cathode comprising the bismuth mixed metal oxide pyrochlore material. 
     
     
         23 . The method of  claim 19 , wherein the anode comprises a composite of the bismuth mixed metal oxide pyrochlore material and one or more noble metals selected from Pt, Ag, Au, Ru, Re, and Pd. 
     
     
         24 . An electrolytic cell for generating a perchlorate salt comprising:
 an anode comprising a bismuth mixed metal oxide pyrochlore material having the general formula A 2 B 2 O 7-x , where A is Bi and B is Ru, Ir, Rh, Sn, Ti, or Pt, and 0≦x≦1;   a cathode;   a chlorate salt in aqueous solution in contact with the anode; and   a source of electric potential and current electrically coupled to the anode and the cathode to produce an operating current density sufficient to oxidize a chlorate salt in aqueous solution to form a perchlorate salt in aqueous solution at the anode.   
     
     
         25 . The electrolytic cell of  claim 24 , wherein B is Ru. 
     
     
         26 . The electrolytic cell of  claim 24 , wherein the electrolytic cell has a cathode comprising the bismuth mixed metal oxide pyrochlore material. 
     
     
         27 . The electrolytic cell of  claim 24 , wherein the anode comprises a composite of the bismuth mixed metal oxide pyrochlore material and one or more noble metals selected from Pt, Ag, Au, Ru, Re, and Pd.