US3293167A - Platinum bismuth alloy coated electrodes - Google Patents

Platinum bismuth alloy coated electrodes Download PDF

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Publication number
US3293167A
US3293167A US527719A US52771966A US3293167A US 3293167 A US3293167 A US 3293167A US 527719 A US527719 A US 527719A US 52771966 A US52771966 A US 52771966A US 3293167 A US3293167 A US 3293167A
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Prior art keywords
platinum
deposit
anodes
solution
bismuth
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Expired - Lifetime
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US527719A
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English (en)
Inventor
Greenspan Lawrence
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BASF Catalysts LLC
Engelhard Industries Inc
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Engelhard Industries Inc
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Publication date
Priority claimed from US228935A external-priority patent/US3267009A/en
Priority to FR949238A priority Critical patent/FR1370405A/fr
Priority to GB39702/63A priority patent/GB1008032A/en
Priority to DEE25650A priority patent/DE1256504B/de
Application filed by Engelhard Industries Inc filed Critical Engelhard Industries Inc
Priority to US527719A priority patent/US3293167A/en
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Assigned to ENGELHARD CORPORATION reassignment ENGELHARD CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: PHIBRO CORPORATION, A CORP. OF DE
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D3/00—Electroplating: Baths therefor
    • C25D3/02—Electroplating: Baths therefor from solutions
    • C25D3/50—Electroplating: Baths therefor from solutions of platinum group metals
    • 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
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D3/00—Electroplating: Baths therefor
    • C25D3/02—Electroplating: Baths therefor from solutions
    • C25D3/56—Electroplating: Baths therefor from solutions of alloys
    • C25D3/567—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of platinum group metals

Definitions

  • This invention relates to the electrolytic deposition of platinum from aqueous solutions, and is particularly concerned with the preparation of platinum-coated base metal articles which find particular utility as nonsacrificial anodes in electrochemical processes.
  • Graphite has a number of disadvantages, however, in that it undergoes continual disintegration and must be replaced frequently, thereby causing interruption of the electrochemical process.
  • the selection of a suitable anode is particularly critical in highly corrosive electrochemical baths, such as the brine solutions used in the manufacture of chlorine, and the use of graphite anodes requires the product to be purified for removal of traces of carbon dioxide which result from oxidation of the graphite anodes.
  • disintegration of the graphite anode causes deposition of fine grains of graphite in the diaphragms which surround the electrodes necessitating replacement of the diaphragms along with the electrodes.
  • platinum metal anodes can be of pure platinum, or, as is known in the art, can comprise a corrosion-resistant core metal such as titanium, silver, and the like, clad with a coherent, impervious platinum metal sheath or covering.
  • anodes which are employed in electrolytic processes are required to have certain favorable currentcarrying characteristics for economic operation.
  • the anode should be highly conductive and capable of carrying a high current load, i.e. operable at the highest possible current density, without undue polarization.
  • polarization of the anode with resultant high overvoltage characteristics reduces the efiiciency of the electrolysis and adversely affects the economics of the electrolytic process.
  • overvoltage characteristics for chlorine discharge using platinum metal anodes are more favorable than when graphite anodes are used. It has been found, however, that at high current densities, e.g. in excess of 200 amperes per square foot and up to about 1000 amperes per square foot, neither platinum sheet nor conventional "ice platinum-coated base metals are entirely satisfactory with respect to chlorine overvoltage characteristics.
  • platinum black deposits i.e., platinum which has been deposited from a bath containing minor amounts of soluble lead compounds, and have found that such platinum black deposits provide excellent overvoltage characteristics
  • platinum black deposits have the disadvantage of extremely poor adherence, and are unsuitable for fabrication of corrosion-resistant anodes since even ordinary Wiping removes the highly corrosive-resistant coating of platinum, and exposes the base metal.
  • the present invention has for its principal object the provision of a stable bath from which platinum deposits can be obtained which have high adherence and are characterised by favorable overvoltage characteristics for chlorine discharge.
  • a further object is the provision of a platinum-coated base metal suitable for use as a non-sacrificial anode.
  • Another object is the provision of a method for depositing platinum from an electroplating bath to provide platinum-coated base metals suitable as anodes in electrochemical processes.
  • adherent platinum deposits having desirable overvoltage characteristics are provided by depositing platinum from an aqueous solution of chloroplatinic acid containing an excess of hydrochloric acid and a small amount of a soluble bismuth compound.
  • Suitable solutions for the practice of the invention contain from about 0.2 to about 2.5 weight percent bismuth based on platinum in the solution.
  • Typical solutions contain from about 5 to about 15 gm./liter platinum (e.g. as H PtCl -6H O), from about 0.02 to about 0.08 gm./liter of bismuth (e.g. as BiCl and from about 1 to about 5 weight percent hydrochloric acid.
  • the amount of hydrochloric acid employed is not critical, but should be at least sufficient to provide a homogeneous solution without formation of deposits during the plating process.
  • the bismuth may be introduced as the chloride BiCl or in the form of the hydroxide, oxide, acetate or the like, sufficient HCl being present to maintain the bismuth in solution as the chloride.
  • the bismuth-containing solutions of the invention gave strongly adherent, uniform matte darkgrey deposits which were highly adherent and exhibited excellent overvoltage characteristics. While the desirable concentration of platinum and bismuth in the plating baths of the invention is indicated above, it will be recognized that the actual deposits which are obtained with such solutions do not necessarily have the same platinumbismuth ratio as present in solution. Thus, at a current density of 15 a.s.f. (amperes per square foot), using a solution containing 0.06 gm./liter BiCl and 8 gm./liter Pt as H PtCl -6H O, the bismuth content of the deposit was found to be about 0.1%. In general, the bismuth content of an effective deposit will 'be between about 0.01 and about 0.1% based on platinum.
  • the baths of the present invention are operated at a temperature between about 20 C. and about 75 C., preferably between about 20 and 60 C., and at a current density in the range of about 10 to about 30 amperes per square foot.
  • the exact time required for obtaining deposits of the desired thickness will vary depending upon the concentration of the solution and the current density employed, for example, from about minutes to one hour or more.
  • any standard accepted process may be employed, such as degreasing, electrocleaning or other operations required to prepare a clean receptive metal surface.
  • metals which may have platinum electrodeposited thereon are silver, nickel, gold, tantalum, tungsten, molybdenum, titanium and rhodium.
  • Platinum-coated titanium is, of course, of particular value in electrolysis of brine because of those characteristics of titanium including light Weight, strength, corrosion-resistance and conductivity which make it of value as a base metal for platinized anodes in brine electrolysis.
  • apparatus consisting basically of a Luggin capillary probe, calomel electrode and a vacuum tube voltmeter having a megohm resistance.
  • the accuracy of the measurement with this instrument is about 10-20 millivolts.
  • the Luggin probe consists of a tube one end of which is bent at right angles and is drawn out into a fine capillary which makes light contact with the surface of the electrode.
  • the other end of the tube is connected with an open top cylindrical separatory funnel in which is immersed a reference electrode (calomel electrode).
  • the funnel and tube are filled with a solution of the electrolyte, in this case a 22% brine solution.
  • This simple device effectively extend the reference electrode electrolyte (in which no current flows) up to the surface of the electrode being studied.
  • the leads from a vacuum tube voltmeter are connected to this electrode and the reference electrode. With this arrangement the electrode potential is measured with practically negligible solution IR drop.
  • the electrolyte used was a 22% solution of sodium chloride contained in a lucite cell.
  • a porous clay cup contained a nickel cathode and prevented mixing of solutions in anolyte and catholyte compartments.
  • Samples for testing were prepared by plating strips of silver and titanium, 3" x 1 wide, with a deposit of microinches of platinum from various solutions. The samples were masked with tape so as to expose a circular area approximately ,4; square inchto the action of the current.
  • the current density range used was from 20 to 1000 amperes per square foot.
  • the sodium chloride electrolyte was employed at temperatures of 25 C. and 70 C.
  • Example I A solution was made up of the following composition:
  • Chlorine overvoltage masurements made in brine solution (22% NaCl) showed no polarization occurring up to current densities of 1000 amperes per square foot.
  • a titanium strip similarly prepared but plated with a 100 microinch deposit in a hexahydroxy platinate bath showed polarization occurring at 200 amperes per square foot accompanied by rapid increase in overvoltage.
  • Example I A solution was made up of the following composition:
  • FIGURES 1, 2 and 3 attached hereto and forming a part hereof, wherein overvoltage measurements for various platinized anodes are plotted as a function of current density (amps/ft?) versus potential (volts).
  • the curves plotted in the figures were obtained by testing the following sample structures used as anode in the test heretofore described:
  • Sample A-Platinum black on silver The conventional solution for producing platinum black was used, containing 30 gm./liter chloroplatinic acid, 0.2 gm./ liter lead acetate, 83 ml./liter con. HCl (normal with respect to HCl). A current density of a.s.f. was used; time of plating, 15 minutes; deposited platinum equivalent to 100 rnicroinches deposit.
  • Sample B-Platinum-bismuth on silver The solution contained gm./liter chlorplatinic acid, 83 m'l./liter HCl, and 0.06 gm./liter Bi(OH) dissolved in HCl. A current density of 15 a.s.f. was used; time of plating, 15 minutes; deposited thickness, 100 rnicroinches.
  • Sample C Platinum-bismuth on titanium as described in Example I; deposited thickness 100 microinches.
  • Sample D Platinum-bismuth on titanium as described in Example I; deposit thickness, 50 rnicroinches.
  • An etched titanium strip was plated with platinum from a solution containing 20 gm./liter sodium hexahydroxy platinate and 10 gin/liter sodium hydroxide at a temperature of 75 C. and current density of 7.5 a.s.f.; time of plating, minutes; deposit thickness, 1-00 rnicroinches.
  • Sample F Platinum on titanium from chloroplatinic acid: An etched titanium strip was plated with platinum from a solution of 20 gm./ liter chloroplatinic acid and 83 ml./ liter hydrochloric acid. A current density of 15 a.s.f. was used; time of plating, 15 minutes; deposit thickness, 100 rnicroinches.
  • Sample H Platinum deposited on silver from platinate solution: A polished strip of silver was plated in the bath described under Sample E at a current density of 7.5 a.s.f. for 25 minutes; thickness of deposit, 100 microinches.
  • Curves 3, 4 and 5 of FIGURE 1 show that platinum electrodeposited on titanium (Sample E) or on silver (Sample H) and pure platinum sheet (Sample G) all show an undesirable rise in potential at applied current density in the range of 100 to 200 a.s.f.
  • FIGURE 2 shows the results obtained by testing anodes prepared in accordance with the invention on a titanium base in comparison with an anode prepared by depositing platinum from chloroplatinic acid in the absence of any added bismuth compound.
  • the hismuth-containing deposits (Curves 6 and 7) show substantially constant potential for current density as high as 1000 a.s.f., and that varying the thickness of the platinum deposit from 50 to 100 rnicroinches has little effect on the anode characteristics.
  • the anode prepared by depositing platinum on titanium from chloroplatinic acid in the absence of added bismuth showed a rapid increase in potential at a current density of 400 a.s.f., and would thus be unsuitable for 'brine electrolysis at high current density.
  • An anode for electrolyzing aqueous salt solutions comprising a metal core having a continuous adherent deposit of platinum containing from 0.01% to about 0.1 weight percent bismuth, the metal core having a composition difi'erent from the adherent deposit.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrodes For Compound Or Non-Metal Manufacture (AREA)
  • Electroplating And Plating Baths Therefor (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
US527719A 1962-10-08 1966-02-15 Platinum bismuth alloy coated electrodes Expired - Lifetime US3293167A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
FR949238A FR1370405A (fr) 1962-10-08 1963-10-01 Procédé de métallisation galvanique
GB39702/63A GB1008032A (en) 1962-10-08 1963-10-08 Electrodeposition of platinum
DEE25650A DE1256504B (de) 1962-10-08 1963-10-08 Verfahren zur galvanischen Herstellung unloeslicher Anoden fuer elektrochemische Prozesse
US527719A US3293167A (en) 1962-10-08 1966-02-15 Platinum bismuth alloy coated electrodes

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US228935A US3267009A (en) 1962-10-08 1962-10-08 Electrodeposition of platinum containing minor amounts of bismuth
US527719A US3293167A (en) 1962-10-08 1966-02-15 Platinum bismuth alloy coated electrodes

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DE (1) DE1256504B (de)
GB (1) GB1008032A (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3373092A (en) * 1963-03-29 1968-03-12 Ajinomoto Kk Electrodeposition of platinum group metals on titanium
US3412000A (en) * 1965-04-14 1968-11-19 M & T Chemicals Inc Cathodic protection of titanium surfaces
US4007107A (en) * 1974-10-18 1977-02-08 Ppg Industries, Inc. Electrolytic anode
US4055477A (en) * 1974-10-18 1977-10-25 Ppg Industries, Inc. Electrolyzing brine using an anode coated with an intermetallic compound
EP1328797B1 (de) * 2000-09-15 2010-03-10 Knut H. Schröder Verwendung einer bismuthlegierungselektrode für die voltammetrische analyse
US11668017B2 (en) * 2018-07-30 2023-06-06 Water Star, Inc. Current reversal tolerant multilayer material, method of making the same, use as an electrode, and use in electrochemical processes

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB201104975D0 (en) 2011-03-24 2011-05-11 Dow Corning Generation of vapour for use in an industrial process
DE102021107826A1 (de) 2021-03-29 2022-09-29 Umicore Galvanotechnik Gmbh Platinelektrolyt

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB189723352A (en) * 1897-10-11 1898-09-03 August Zimmermann Improvements in the Manufacture of Electrodes for Electrolytic Processes.

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB189723352A (en) * 1897-10-11 1898-09-03 August Zimmermann Improvements in the Manufacture of Electrodes for Electrolytic Processes.

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3373092A (en) * 1963-03-29 1968-03-12 Ajinomoto Kk Electrodeposition of platinum group metals on titanium
US3412000A (en) * 1965-04-14 1968-11-19 M & T Chemicals Inc Cathodic protection of titanium surfaces
US4007107A (en) * 1974-10-18 1977-02-08 Ppg Industries, Inc. Electrolytic anode
US4055477A (en) * 1974-10-18 1977-10-25 Ppg Industries, Inc. Electrolyzing brine using an anode coated with an intermetallic compound
EP1328797B1 (de) * 2000-09-15 2010-03-10 Knut H. Schröder Verwendung einer bismuthlegierungselektrode für die voltammetrische analyse
US11668017B2 (en) * 2018-07-30 2023-06-06 Water Star, Inc. Current reversal tolerant multilayer material, method of making the same, use as an electrode, and use in electrochemical processes
US12305300B2 (en) 2018-07-30 2025-05-20 Water Star, Inc. Current reversal tolerant multilayer material, method of making the same, use as an electrode, and use in electrochemical processes

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Publication number Publication date
DE1256504B (de) 1967-12-14
GB1008032A (en) 1965-10-22

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Owner name: ENGELHARD CORPORATION 70 WOOD AVENUE SOUTH, METRO

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:PHIBRO CORPORATION, A CORP. OF DE;REEL/FRAME:003968/0801

Effective date: 19810518