Electrode
An electrode ( 10 ) is disclosed in which a first layer ( 30 ) of TiO x with a porosity in the range 0-3% is present on at least one surface of an electrode substrate ( 20 ), a second layer ( 40 ) of TiO x with a porosity of greater than 3 and up to 20% is present on the first layer ( 30 ) of TiO x . An electro-catalytic layer ( 50 ) is present on the second layer ( 40 ) of TiO x . x is in the range 1-2 for the first ( 30 ) and second layer ( 40 ) of TiO x . A process for the manufacture of the electrode ( 10 ) is disclosed as are uses thereof.
1. A cathode comprising:
a cathode substrate comprising titanium and/or an alloy thereof and having at least one surface;
a first layer of TiO x with a porosity of from 0.1% to 3% disposed on the at least one surface of the cathode substrate;
a second layer of TiO x with a porosity of greater than 3% and up to 20% disposed on the first layer of TiO x ; and
an electro-catalytic layer disposed on the second layer of TiO x and comprising RuO 2 ,
wherein x is from 1 to 1.99 for the first and second layers of TiO x , and
wherein a thickness of the first layer of TiO x is at least 20 μm and a thickness of the second layer of TiO x is at least 20 μm.
2. The cathode according to claim 1 , wherein a total thickness of the first layer of TiO x and the second layer of TiO x is from 40 to 190 μm.
3. The cathode according to claim 1 , wherein x is from 1.6 to 1.9 for the first layer of TiO x or the second layer of TiO x .
4. The cathode according to claim 1 , wherein the electro-catalytic layer further comprises Ru x Ti 1-x O y , wherein x of the Ru x Ti 1-x O y is from 0.5 to 1 and y of the Ru x Ti 1-x O y is up to 2.
5. The cathode according to claim 1 , wherein the electro-catalytic layer has a metals and/or oxides content of from 1 to 40 g/m 2 .
6. A method comprising using the cathode of claim 1 as a cathode in an electrolytic process.
7. The method according to claim 6 , wherein the electrolytic process comprises manufacture of alkali metal chlorate.
8. A process of manufacturing a cathode, the process comprising the steps of:
(i) providing a cathode substrate comprising titanium and/or an alloy thereof;
(ii) coating at least one surface of the cathode substrate by plasma spraying to form a first layer of TiO x with a porosity of from 0.1% to 3%;
(iii) coating by plasma spraying on the first layer of TiO x to form a second layer of TiO x with a porosity of greater than 3% and up to 20%; and
(iv) coating an electro-catalytic layer on the second layer of TiO x ,
wherein x is from 1 to 1.99 for the first and second layers of TiO x , thereby forming the cathode comprising:
the cathode substrate having the at least one surface;
the first layer of TiO x with a porosity of from 0.1% to 3% disposed on the at least one surface of the cathode substrate;
the second layer of TiO x with a porosity of greater than 3% and up to 20% disposed on the first layer of TiO x ; and
the electro-catalytic layer disposed on the second layer of TiO x and comprising RuO 2 ,
wherein a thickness of the first layer of TiO x is at least 20 μm and a thickness of the second layer of TiO x is at least 20 μm.
9. The process according to claim 8 , wherein the at least one surface of the cathode substrate is roughened to provide an R a value of from 1 to 6 μm prior to step (ii).
10. The process according to claim 9 , wherein the roughened cathode substrate does not undergo a pickling procedure.
11. The process according to claim 8 , wherein coating the electro-catalytic layer on the second layer of TiO x further comprises thermolysis of a combination of ruthenium and titanium compounds.
12. The process according to claim 8 , wherein coating the electro-catalytic layer on the second layer of TiO x provides a metals and/or oxides content of from 1 to 40 g/m 2 to the electro-catalytic layer.
13. The cathode according to claim 1 , wherein
a total thickness of the first layer of TiO x and the second layer of TiO x is from 40 to 190 μm wherein the first layer has a porosity either of from 0.1 to 2.5% or from 0.5 to 1.8%;
a thickness of the first layer of TiO x and a thickness of second layer of TiO x is at least 20 μm;
x is from 1.6 to 1.9 for the first layer of TiO x and/or the second layer of TiO x ; and
the electro-catalytic layer has a metals and/or oxides content of from 1 to 40 g/m 2 .
14. The cathode according to claim 1 wherein the first layer has a porosity of from 0.1 to 2.5%.
15. The cathode according to claim 13 , wherein the cathode substrate is Commercially Pure Grade 1 Titanium.
16. The cathode according to claim 1 , wherein the cathode substrate is Commercially Pure Grade 1 Titanium.
17. The process according to claim 8 , wherein the cathode substrate is Commercially Pure Grade 1 Titanium.
18. The process according to claim 1 , wherein the first and second layers are devoid of cracking.