GB2146660A

GB2146660A - Surface-activated amorphous alloys for electrodes in the electrolysis of solutions

Info

Publication number: GB2146660A
Application number: GB08423668A
Authority: GB
Inventors: Koji Hashimoto; Naokazu Kumagai; Asahi Kawashima; Katsuhiko Asami; Tsuyoshi Masumoto
Original assignee: Daiki Engineering Co Ltd
Current assignee: Daiki Engineering Co Ltd
Priority date: 1983-09-19
Filing date: 1984-09-19
Publication date: 1985-04-24
Also published as: JPS6063336A; JPH0468394B2; GB2146660B; GB8423668D0

Abstract

Amorphous alloys for electrodes in the electrolysis which are surface-activated and consist of 10-30 atomic percent P and/or Si, 20 atomic percent or more Pd and 20-50 atomic percent Ru, Rh, Ir and/or Pt. The alloys sometimes contain further 15 atomic percent or less Ti, Zr, Nb and/or Ta. By surface activating certain amorphous alloy electrodes (generally known from GB 2051158B) their electrocatalytic activity is enhanced. The electrodes may be surface activated by diffusing zinc into the surface and then leaching the zinc from the surface. The electrodes may be used from the electrolysis of dilute sodium chloride solutions to produce sodium chlorate, for the electrolysis of bromides or of organic compounds or as electrodes in batteries or fuel cells.

Description

SPECIFICATION Surface-activated amorphous alloys for electrodes in the electrolysis of solutions The present invention relates to surface-activated amorphous alloys which are particularly suitable as electrode materials for the electrolysis of unheated, relatively dilute salt solutions such as the electrolysis of sea water to produce sodium hypochlorate.

It is known in this field to use electrodes made of corrosion-resistant metals such as titanium coated with noble metals. However, when such electrodes are used as anodes in the electrolysis of sea water, the noble metal coatings are corroded and sometimes peeled off from the titanium substrate. On the other hand, modern industries are using composite oxide electrodes consisting of corrosion-resistant metals as a substrate on which composite oxides such as platinum oxide and titanium oxide are coated. When these electrodes are used as anodes in the electrolysis of sea water, they have disadvantages that the composite oxides are sometimes peeled off from the metal substrate and the chlorine gas produced is contaminated by a large amount of oxygen.

In general, ordinary alloys are crystalline in the solid state. However, rapid quenching of some alloys with specific ompositions from the liquid state gives rise to solidification to an amorphous structure. These alloys are called amorphous alloys.

The amorphous alloys have significantly high mechanical strength in comparison with the conventional industrial alloys. Some amorphous alloys with the specific compositions have extremely high corrosion resistance that cannot be obtained in ordinary crystalline alloys.

One of the present inventors previously obtained a U.K. Patent GB 20511288 entitled "Corrosion resistant amorphous noble metal-base alloys and electrodes made therefrom", showing that when these alloys are used as anodes in the electrolysis of 4 M NaCI aqueous solutions of pH 4 or 2 and 80 C or saturated KCI solution of 80"C they posses very high electrocatalytic activity for chlorine evolution along with the high corrosion resistance but are almost inert for parasitic oxygen evolution.

The U.K. Patent GB 2051128 B discloses: Amorphous alloys which are prepared by rapid quenching from the liquid state and consist of (1) 10-40 atomic percent of a non-metallic component comprising P and/or Si of which up to 7 atomic percent may be replaced by B and/or C, and 90-60 atomic percent of a metallic component comprising (2) two or more Pd, Rh and Pt; (2') two or more Pd, Rh and Pt and 25 atomic percent or less Ti, Zr, Nb and/or Ta; (2") Pd, Rh and/or Pt and 80 atomic percent or less Ir and/or Ru or (2"') Pd, Rh and/or Pt, 80 atomic percent or less Ir and/or Ru and 25 atomic percent or less Ti, Zr, Nb and/or Ta. The above atomic percentages are based on the total composition of the alloy.

The present inventors have further examined the anode characteristics of the previously patented amorphous alloys as follows: Using NaCI solutions like sea water, which were more dilute and cooler than 4 M Nacl solution at 80"C, the present inventors carried out the electrolysis without separating the anolyte and catholyte as to produce sodium hypochlorate by direct reaction of chlorine formed on the anode with sodium hydroxide formed on the cathode.

It was found that there are two ranges of alloy compositions of high and relatively low electrocatalytic activities for the production of sodium hypochiorate. The present invention was made by finding that, when the alloys having high electrocatalytic activity are surface-activated by the method as described in the Japanese Patent Kokai No. 200565/82 by two of the present authors, the surface-activated alloys possess superior electrocatalytic activity as anodes for the production of sodium hypochlorate by the electrolysis of unheated Nacl solutions whose Nacl concentrations are similar to that of sea water.

The present invention was thus made and aims to provide surface-activated amorphous alloys which have high corrosion resistance and high electrocatalytic activity for the production of sodium hypochlorate by the electrolysis of unheated dilute NaCI solutions like sea water without separating anode and cathode compartments.

The present invention provides surface-activated amorphous alloys obtained by rapid quenching from the liquid state followed by the surface activation treatment. The alloys consist of (1) 10-30 atomic percent of a metalloid component comprising P and/or Si of which upto 7 atomic percent may be replaced by B and/or C, and 90-70 atomic percent of a metallic component comprising (2) 20 atomic percent or more Pd and 20-50 atomic percent of Ru, Rh, Ir and/or Pt or (2') 20 atomic percent or more Pd, 20-50 atomic percent of Ru, Rh, Ir and/or Pt and 15 atomic percent or less Ti, Zr, Nb and/or Ta. The above atomic percentages are based on the total composition of the alloy.

The amorphous alloys prepared by rapid quenching of molten alloys with compositions as defined above are single phase alloys in which the elements are uniformly distributed. The preparation of metal electrodes having the catalytic activity selective for a specific chemical reaction generally requires alloying with necessary amounts of benificial elements. However, addition of large amounts of various elements to crystalline metals leads often to formation of multiple phases of different chemical properties and to poor mechanical strength. On the contrary, the amorphous alloys of the present invention are chemically homogeneous solid solution prepared by rapid quenching from the liquid state and hence possess high corrosion resistance and mechanical strength as well as stable and high electrocatalytic activity.

On the other hand for the electrolysis of sea water the enhancement of electrocatalytic activity by the above mentioned surface activation treatment is needed which consists of heating for diffusive permeation of zinc into the surface layer of the alloys followed by leaching of zinc. When the surface activation treatment is applied to the crystalline metals the diffusive permeation of zinc occurs mostly along grain boundaries, and hence subsequent leaching of zinc leads to grain boundary embrittlement. Therefore the surface activation treatment is not effective in improving the catalytic activity of crystalline metals. On the contrary the amorphous alloys of the present invention are not crystalline and hence have no grain boundaries.

Therefore they do not suffer grain boundary embrittlement. Furthermore, the diffusion of zinc inside the amorphous alloys is fast even at relatively low temperatures lower than the crystallizationtemperatures of the alloys and takes place uniformly in the entire surface layer. Thus the surface activation treatment is quite effective in enhancing the electro-catalytic activity of the entire surface of the amorphous alloys.

Consequently, surface-activated amorphous alloys of the present invention possess the superior characteristics as anode materials in the electrolysis of aqueous solutions of alkali halides. The diffusive permeation of zinc, for example, can be performed by heat treatment of the amorphous alloys in zinc powder or by heat treatment of zinc-plated amorphous alloys. Crystallization of the amorphous alloys due to heat treatment at temperatures higherthanthecrystallization temperatures of the amorphous alloys is not particularly detrimental for the surface activation, although it is desirable to avoid complete crystallization since it results in embrittlement of the alloys.

A suitable preparation method of amorphous alloys of the present invention is as follows: The amorphous alloys with compositions mentioned above can be prepared by rapid quenching from the liquid state at a cooling rate higher than about 10,000#C/sec. If the cooling rate is slower than about 10,000 C/sec, vitrification of the whole alloy becomes incomplete. In principle, the amorphous alloys of the present invention can be produced by any suitable apparatus which provides a cooling rate higher than about 10,000 C/sec.

One embodiment of apparatus for preparing the amorphous alloys of the present invention is shown in the single Figure. In the Figure, a quartz tube (2) has a nozzle (3) at its lower end in the vertical direction, and raw materials (4) and an inert gas for preventing oxidation of the raw materials are fed from the inlet (1). A heater (5) is placed around the quartz tube (2) so as to heat the raw materials (4). A high speed wheel (7) is placed below the nozzle (3) and is rotated by a motor (6).

For the preparation of the amorphous alloys the raw materials (4) having the prescribed compositions are melted by the heater (5) in the quartz tube under an inert gas atmosphere. The molten alloy impinges under the pressure of the inert gas onto the outer surface of the wheel (7) which is rotated at a speed of 1,000 to 10,000 rpm whereby an amorphous alloy is formed as a long thin plate, which may for example have a thickness of 0.1 mm, a width of 10 mm and a length of several meters.

The amorphous alloys of the present invention produced by the above-mentioned procedure generally have a Vickers hardness of 400 to 600 and a tensile strength of 120 to 200 kg/mm2 and have excellent mechanical properties typical of amorphous alloys, particularly as regards the possibility of complete bending and cold rolling to a degree greater than 50% reduction in thickness.

The amorphous alloys of the present invention will be illustrated in more detail by way of example only.

Energy saving Electrodes with a long life should have characteristics of high and stable electrocatalytic activity in electrolytic reactions for a long time along with high corrosion resistance and high mechanical strength under the electrolytic conditions.

As described above, it is important for the alloys to have the amorphous structure so that they become a single phase solid solution regardless of complicated compositions and easily surface-activated and hence they possess high and stable electrocatalytic activity as well as extremely high corrosion resistance and excellent mechanical properties.

The alloys with the specific compositions defined above can form the amorphous structure and satisfy the requirements of high and stable electrocatalytic activities along with extremely high corrosion resistance and excellent mechanical properties.

Typical compositions are shown in Table 1.

TABLE 1 Composition of Amorphous Alloys of Present Invention (atomic percent) Specimen No. Pd P Si Ru Rh lr Pt Ti Zr Nb Ta 1 60 20 0 20 0 0 0 0 0 0 0 2 50 20 0 30 0 0 0 0 0 0 0 3 41 19 0 40 0 0 0 0 0 0 0 4 56 19 0 0 25 0 0 0 0 0 0 5 56 10 9 0 25 0 0 0 0 0 0 6 56 5 14 0 25 0 0 0 0 0 0 7 56 0 19 0 25 0 0 0 0 0 0 8 50 20 0 0 30 0 0 0 0 0 0 TABLE 1 (Cont'd) Composition of Amorphous Alloys of Present Invention (atomic percent) Specimen No.Pd P Si Ru Rh Ir Pt Ti Zr Nb Ta 9 38 22 0 0 40 0 0 0 0 0 0 10 60 20 0 0 0 20 0 0 0 0 0 11 50 20 0 0 0 30 0 0 0 0 0 12 35 25 0 0 0 40 0 0 0 0 0 13 30 20 0 0 0 50 0 0 0 0 0 14 60 20 0 0 0 0 20 0 0 0 0 15 50 10 10 0 0 0 30 0 0 0 0 16 50 10 0 0 0 0 40 0 0 0 0 17 45 15 10 0 25 0 0 5 0 0 0 18 50 17 0 0 25 0 0 8 0 0 0 19 45 16 0 5 20 0 0 14 0 0 0 20 45 0 25 0 25 0 0 0 5 0 0 21 50 20 0 0 25 0 0 0 0 5 0 22 53 17 0 0 25 0 0 0 0 0 5 23 51 19 0 0 20 0 0 0 0 0 10 24 51 19 0 5 25 0 0 0 0 0 0 25 46 19 0 10 25 0 0 0 0 0 0 26 51 19 0 0 25 5 0 0 0 0 0 27 46 19 0 0 25 10 0 0 0 0 0 28 31 19 0 10 25 15 0 0 0 0 0 29 54 19 0 0 25 0 2 0 0 0 0 30 51 19 0 0 25 0 5 0 0 0 0 31 46 19 0 0 25 0 10 0 0 0 0 32 46 19 0 5 0 30 0 0 0 0 0 33 41 19 0 10 0 30 0 0 0 0 0 34 46 19 0 0 5 30 0 0 0 0 0 35 41 19 0 0 10 30 0 0 0 0 0 36 46 19 0 0 0 30 5 0 0 0 0 37 41 19 0 0 0 30 10 0 0 0 0 38 40 19 0 10 10 10 10 0 0 0 0 39 50 20 0 10 10 0 0 0 0 0 10 40 35 20 0 20 10 0 0 0 0 0 15 41 45 20 0 10 15 0 0 0 0 0 10 42 45 20 0 5 25 0 0 5 0 0 0 43 45 20 0 0 25 5 0 5 0 0 0 44 45 20 0 0 25 0 5 5 0 0 0 45 44 20 0 1 0 30 0 5 0 0 0 46 43 20 0 2 0 30 0 5 0 0 0 47 44 20 0 0 1 30 0 5 0 0 0 48 43 20 0 0 2 30 0 5 0 0 0 49 44 20 0 0 0 30 1 5 0 0 0 50 43 20 0 0 0 30 2 5 0 0 0 51 45 20 0 0 25 0 ~ 0 5 5 0 0 52 45 20 0 0 25 0 0 5 0 5 0 53 45 20 0 0 25 0 0 5 0 0 5 54 56 20 0 10 10 0 0 4 0 0 0 55 48 10 10 5 20 0 5 2 0 0 0 56 58 10 10 5 10 0 5 2 0 0 0 57 46 10 9 0 25 0 0 10 0 0 0 58 46 10 9 5 25 0 0 5 0 0 0 59 46 10 9 0 25 0 5 5 0 0 0 60 20 10 5 20 10 5 25 2 3 0 0 The surface-activated amorphous alloys of the present invention have excellent characteristics in comparison with conventional electrodes such as metallic electrodes made of corrosion-resistant metals coated with platinum metal or platinum-iridium alloys, composite oxide electrodes made of corrosionresistant metals coated with oxides of noble metals like palladium, and others.

For example, when the surface-activated amorphous alloys of the present invention are used as anodes for electrolysis of sea water, the overvoltages for chlorine evolution are comparable with or lower than those of the conventional electrodes.

Therefore, the surface-activated amorphous alloys of the present invention have excellent characteristics as energy saving electrode materials with a long life. In particular, the surface-activated amorphous alloys of the present invention are especially suitable as anodes for electrolysis of aqueous solutions of various metal halides.

The reasons for the proportions defined for the components in the amorphous alloys of the present invention will be illustrated as follows: The present of P and/or Si is necessary for forming the amorphous structure and also for rapid formation of the protective passive film. However, when the total content of the metalloid component comprising P and/or Si is less than 10 atomic percent it is difficult to form the amorphous structure and when the total content exceeds 30 atomic percent, the surface activation treatment is apt to lead to embrittlement of the alloys. Therefore the total content of this component must be in a range of 10 to 30 atomic percent. In particular, the amorphous structure can be easily obtained when the total content of P and/or Si is in a range of 16 to 25 atomic percent.

It is known that the addition of B or C is also effective in forming the amorphous structure for iron-cobaltor nickel-base alloys. The amorphous alloys of the present invention, however, are rendered brittle to some extent by the addition of large amounts of B or C, and hence not all of the P and/or Si could be substituted by B and/or C but substitution of P and/or Si to extent of 7 atomic percent or less by B and/or C is possible since the ductility of the alloys is then maintained.

The element Pd is the main metallic component of the amorphous alloys of the present invention and is especially effective in oxidizing halide ions as well as forming the amorphous structure. In particular, the electrodes serving the purpose of the present invention are needed to have especially high electrocatalytic activity because of the electrolysis of dilute sodium chloride solutions without being heated in contrast to the electrolysis of hot concentrated sodium chloride solutions. Accordingly not all of the element Pd could be substituted by other platinum group metals, and the Pd content of the amorphous alloys must be 20 atomic percent or more.

The elements Ru, Rh, Ir and Pt are beneficial in enhancing the corrosion resistance of amorphous Pd-base alloys containing P and/or Si and are not harmful or rather effective in improving the electrocatalytic activity.

Accordingly 20 atomic percent or more Ru, Rh, Ir and/or Pt must be contained in the amorphous alloys to ensure the corrosion resistance during the electrolysis. However, when extremely large amounts of Ru, Rh, Ir and/or Pt are added, it becomes difficult to enhance the electrocatalytic activity by the surface activation treatment. Furthermore, when extremely large amounts of Ru, Rh and/or Ir are added the alloys tend to be brittle after the surface activation treatment. Therefore the contents of Ru, Rh, Ir and/or Pt must be 50 atomic percent or less.

The elements Ti, Zr, Nb and Ta are significantly effective in increasing the corrosion resistance and facilitating the formation of the amorphous structure. However, the addition of Ti, Zr, Nb and/or Ta in large amounts makes it difficult to enhance the electrocatalytic activity by the surface activation treatment.

Therefore, when Ti, Zr, Nb and/or Ta are added, the total content of these elements in the amorphous alloys must be 15 atomic percent or less.

Therefore, the amorphous alloys of the present invention contain Pd as the main metallic component having the high electrocatalytic activity for electrolytic oxidation of halides and proper amounts of Ru, Rh, Ir, Pt, Ti, Zr, Nb and Ta which improves corrosion resistance, and their electrocatalytic activities are further enhanced by the surface activation treatments.

Consequently, the surface-activated amorphous alloys of the present invention can be regarded as energy-saving electrodes with a long life since they possess both high electrocatalytic activity and high corrosion resistance, and hence they can be used as effective anodes, in the electrolysis which requires extremely active electrodes like in the electrolysis of dilute metal halides solutions at relatively low temperatures.

The surface-activated amorphous alloys of the present invention can be used as the following electrodes other than the above application: 1. Electrodes for the electrolysis of dilute sodium chloride solutions which produce sodium hypochlorate for sterilization of water supply and sewage.

2. Electrodes for the electrolysis of bromides.

3. Electrodes in batteries operating at ambient temperature for storage of electricity.

4. Fuel electrodes for fuel cells.

5. Electrodes for the electrolysis of organic materials.

The purpose of the present invention can be also attained by addition of a small amount (about 2 atomic percent) of other elements such as V, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Ag, Au, Sn, Al, Ge and S.

The surface-activated amorphous alloys of the present invention will be further illustrated by an example which is provided only for purpose of illustration and is not intended to be limiting the present invention.

Example Amorphous alloys whose compositions are shown in Table 1 were prepared by rapid quenching from the liquid state by using the apparatus shown in Figure 1. The amorphous alloy sheets prepared were 0.01 - 0.05 mm thick, 1 - 10 mm wide and 3 - 20 m long. Electrodeposition of zinc was carried out galvanostatically on the amorphous alloy sheets of the desired length at 20 aA/cm2 in the aqueous solution of 30 C consisting of 400 g/l ZnSo47H20 and 70 g/l Na2SO4. Subsequently, the electrodeposited zinc was diffused into the surface layer of the amorphous alloys by heating at 200 - 3000C for 30 min. The specimen electrodes were obtained after leaching of zinc from the alloys into heated 6 N KOH solution.Using the specimen electrodes thus prepared, anodic polarization curves of the surface-activated amorphous alloys were measured by both galvanostatically and potentiostatically in NaCI aqueous solutions of various concentrations at 30 C. As an example, Table 2 shows the current densities measured at 1.15 V vs. SCE in 0.5 N NaCI solution for the surface-activated amorphous alloys whose heat treatment in the surface activation treatment was carried out at 300"C.

The higher the current density, the higher is the efficiency for the production of sodium hypochlorate and hence the higher is the electrocatalytic activity.

The surface-activated amorphous alloys of the present invention possess higher electrocatalytic activities than that of Pt-coated titanium electrode which is shown as an example for comparison. The majority of the surface-activated amorphous alloys of the present invention have higher electrocatalytic activities than that of PdO-coated titanium electrode and the many surface-activated amorphous alloys of the present invention show higher electrocatalytic activities than that of Pt-ir-coated titanium electrode which is known to possess the highest catalytic activity among conventional electrodes for electrolysis of sea water.

TABLE 2 Current Densities of the Surface-ActivatedAmorphous Alloys of the Present Invention and Currently Used Electrodes at 1.15 V {SUE) Estimated from the Potentiodynamic Polarization Curves Measured in 0.5 M NaCI Aqueous Solution at 300 C. The Amorphous Alloys of Present Invention were Surface-Activated by The Diffusive Permeation Treatment of Electrodeposited Zinc into the Alloys at 300 C, followed by Leaching of Zinc.

Electrode Current density (A/cm2) No.2 7500 No. 4 360 No. 5 530 No.6 700 No.7 1440 No.11 480 No.12 510 No. 14 1170 No. 16 780 No.23 810 No. 29 630 No. 30 300 No. 32 1510 No.33 200 No.34 320 No. 36 570 No. 37 290 No. 41 300 No. 42 190 No.43 130 No.44 330 No. 45 500 No.46 480 No. 47 320 No.48 300 No.49 340 No. 50 320 No.57 390 No. 58 1300 No. 59 370 No.60 350 TABLE 2 (Cont'd) Examples for Comparison* Pt/Ti 12 Pt-Ir/Ti 770 PdO/Ti 230 * Currently used electrodes of titanium coated with crystalline metals or oxide

Claims

1. An amorphous alloy for use as an electrode in electrolysis, the surface of the alloy being surface-activated, the alloy consisting of: (1) from 10 to 30 atomic percent of a metalloid component comprising P and/or Si of which up to 7 atomic percent may be substituted with B and/or C, and (2) from 90 to 70 atomic percent of a metallic component comprising 20 atomic percent of more Pd and from 20 to 50 atomic percent Ru, Rh, Ir and/or Pt.

2. An amorphous alloy for use as an electrode in electrolysis, the surface of the alloy being surface-activated, the alloy consisting of: (1) from 10 to 30 atomic percent of a metalloid component comprising P and/or Si of which up to 7 atomic percent may be substituted with B and/or C, and (2) from 90 to 70 atomic percent of a metallic component comprising 20 atomic percent or more Pd, from 20 to 50 atomic percent of Ru, Rh, Ir and/or Pt and 15 atomic percent or less of Ti, Zr, Nb and/or Ta.

3. An amorphous alloy according to claim 1 or claim 2 wherein the surface of the alloy is surface-activated by diffusing zinc into the surface and then leaching the zinc from the surface.

4. An amorphous alloy according to claim 3 wherein the zinc is diffused into the surface by heat treatment of the amorphous alloy in zinc powder.

5. An amorphous alloy according to claim 3 wherein the zinc is diffused into the surface by heat treatment of the amorphous alloy which has been zinc-plated.

6. An amorphous alloy according to claim 4 or claim 5 wherein the heat treatment is carried out at from 200 to 3000C for 30 minutes.

7. An amorphous alloy according to any one of claims 3 to 6 wherein the leaching step is carried out by contacting the surface with heated 6N KOH solution.

8. An amorphous alloy according to claim 1 substantially as hereinbefore described.

9. An amorphous alloy substantially as hereinbefore described in the foregoing Example.

10. A method of making an amorphous alloy for use as an electrode and electrolysis, the surface of the alloy being surface activated and the alloy consisting of: (1) from 10 to 30 atomic percent of a metalloid component comprising P and/or Si of which up to 7 atomic percent may be substituted with B and/or C, and (2) from 90 to 70 atomic percent of a metallic component comprising 20 atomic percent or more Pd and from 20 to 50 atomic percent Ru, Rh, Ir and/or Pt; or (1) from 10 to 30 atomic percent of a metalloid component comprising P and/or Si of which up to 7 atomic percent may be substituted with B and/or C, and (2) from 90 to 70 atomic percent of a metallic component comprising 20 atomic percent or more Pd, from 20 to 50 atomic percent of Ru, Rh, Ir and/or Pt and 15 atomic percent or less of Ti, Zr, Nb and/or Ta, the method comprising the steps of producing a sheet of the amorphous alloy by quenching the alloy from the liquid state and activating the surface of the amorphous alloy by a surface-activation treatment.

11. A method according to claim 10 wherein the surface of the alloy is surface-activated by diffusing zinc into the surface and then leaching the zinc from the surface.

12. A method according to claim 11 wherein the zinc is diffused into the surface by heat treatment of the amorphous alloy in zinc powder.

13. A method according to claim 11 wherein the zinc is diffused into the surface by heat treatment of the amorphous alloy which has been zinc-plated.

14. A method according to claim 12 or 13 wherein the heat treatment is carried out at from 200 to 3000C for 30 minutes.

15. A method according to any one of claims 11 to 14 wherein the leaching step is carried out by contacting the surface with heated 6N KOH solution.

16. A method according to claim 10 substantially as hereinbefore described.

17. A method of making an amorphous alloy for use as an electrode in electrolysis substantially as hereinbefore described in the foregoing Example.

18. An electrode including an amorphous alloy according to any of claims 1 to 9.