Electrode for Electrolysis

Abstract

The present technology relates to an electrode for electrolysis which has a coating layer containing an ytterbium oxide, wherein the electrode for electrolysis of the present technology is characterized by exhibiting excellent durability and improved overvoltage. Further, the present technology relates to a method of preparing an electrode for electrolysis which includes: applying a coating composition on at least one surface of a metal base, and coating by drying and heat-treating the metal base on which the coating composition has been applied, wherein the coating composition includes a ruthenium precursor and an ytterbium precursor.

Claims

1. An electrode for electrolysis, the electrode comprising: a metal base layer; and a coating layer containing a ruthenium oxide and an ytterbium oxide, wherein the coating layer is formed on at least one surface of the base layer.

2. The electrode for electrolysis of claim 1, wherein a molar ratio of a ruthenium element to an ytterbium element, which are contained in the coating layer, is in a range of 100:5 to 100:30.

3. The electrode for electrolysis of claim 1, wherein the coating layer further contains a platinum group oxide.

4. The electrode for electrolysis of claim 3, wherein a molar ratio of a ruthenium element to a platinum group element, which are contained in the coating layer, is in a range of 100:2 to 100:20.

5. The electrode for electrolysis of claim 1, wherein the coating layer further contains a cerium oxide.

6. The electrode for electrolysis of claim 5, wherein a molar ratio of a ruthenium element to a cerium element, which are contained in the coating layer, is in a range of 100:5 to 100:30.

7. A method of preparing an electrode for electrolysis, the method comprising: applying a coating composition on at least one surface of a metal base; and forming coating by drying and heat-treating the metal base on which the coating composition has been applied, wherein the coating composition comprises a ruthenium precursor and an ytterbium precursor.

8. The method of claim 7, wherein the coating composition further comprises a platinum group precursor.

9. The method of claim 7, wherein the coating composition further comprises a cerium precursor.

10. The method of claim 7, wherein the ruthenium precursor is at least one selected from the group consisting of ruthenium hexafluoride (RuF.sub.6), ruthenium(III) chloride (RuCl.sub.3), ruthenium(III) chloride hydrate (RuCl.sub.3xH.sub.2O), ruthenium(III) bromide (RuBr.sub.3), ruthenium(III) bromide hydrate (RuBr.sub.3xH.sub.2O), ruthenium iodide (RuI.sub.3), and ruthenium acetate.

11. The method of claim 7, wherein the ytterbium precursor is at least one selected from the group consisting of ytterbium carboxylate, ytterbium nitrate, ytterbium carbonate, ytterbium chloride, ytterbium fluoride, ytterbium oxide, ytterbium sulfonate, and hydrates thereof.

12. The method of claim 8, wherein the platinum group precursor is at least one selected from the group consisting of chloroplatinic acid hexahydrate (H.sub.2PtCl.sub.6.6H.sub.2O), diamine dinitro platinum (Pt(NH.sub.3).sub.2(NO).sub.2), platinum(IV) chloride (PtCl.sub.4), platinum(II) chloride (PtCl.sub.2), potassium tetrachloroplatinate (K.sub.2PtCl.sub.4), and potassium hexachloroplatinate (K.sub.2PtCl.sub.6).

13. The method of claim 9, wherein the cerium precursor is at least one selected from the group consisting of cerium(III) nitrate hexahydrate (Ce(NO.sub.3).sub.3.6H.sub.2O), cerium(IV) sulfate tetrahydrate (Ce(SO.sub.4).sub.2.4H.sub.2O), and cerium(III) chloride heptahydrate (CeCl.sub.3.7H.sub.2O).

14. The method of claim 7, wherein the coating composition further comprises at least one amine-based additive selected from the group consisting of melamine, ammonia, urea, 1-propylamine, 1-butylamine, 1-pentylamine, 1-heptylamine, 1-octylamine, 1-nonylamine, and 1-dodecylamine.

Description

EXAMPLE 1

[0061] 2.41 mmol of ruthenium(III) chloride hydrate, 0.1928 mmol of platinum(IV) chloride, and 0.482 mmol of ytterbium acetate tetrahydrate were sufficiently dissolved for 1 hour in the mixed solvent of the above materials, and 0.045 g of urea was added and mixed to prepare a coating composition.

[0062] The coating composition was coated on the previously pretreated metal base using a brush, and the coated metal base was put in a convection drying oven and dried at 180° C. for 10 minutes. Thereafter, it was put in an electric heating furnace at 500° C. and was further heat-treated for 10 minutes, and, after the above-described coating, drying, and heat treatment processes were repeated 9 times, an electrode for electrolysis was finally prepared by performing a final heat treatment at 500° C. for 1 hour.

EXAMPLE 2

[0063] An electrode for electrolysis was prepared in the same manner except that 0.241 mmol of cerium(III) nitrate hexahydrate was further added to the coating composition in Example 1 and 0.241 mmol of ytterbium acetate tetrahydrate was added.

EXAMPLE 3

[0064] An electrode for electrolysis was prepared in the same manner except that platinum(IV) chloride was not added to the coating composition in Example 1.

EXAMPLE 4

[0065] An electrode for electrolysis was prepared in the same manner except that platinum(IV) chloride was not added to a coating composition in Example 2.

EXAMPLE 5

[0066] An electrode for electrolysis was prepared in the same manner except that 0.3615 mmol of the cerium precursor and 0.1205 mmol of the ytterbium precursor were added in Example 2.

EXAMPLE 6

[0067] An electrode for electrolysis was prepared in the same manner except that 0.1205 mmol of the cerium precursor and 0.3615 mmol of the ytterbium precursor were added in Example 2.

COMPARATIVE EXAMPLE 1

[0068] An electrode for electrolysis was prepared in the same manner except that ytterbium acetate tetrahydrate was not added and 0.482 mmol of cerium(III) nitrate hexahydrate was added in Example 2.

COMPARATIVE EXAMPLE 2

[0069] An electrode for electrolysis was prepared in the same manner except that platinum(IV) chloride was not added to a coating composition in Comparative Example 1.

COMPARATIVE EXAMPLE 3

[0070] An electrode for electrolysis was prepared in the same manner except that 0.241 mmol of praseodymium(III) chloride (PrCl3) was added instead of the ytterbium precursor in Example 2.

COMPARATIVE EXAMPLE 4

[0071] An electrode for electrolysis was prepared in the same manner except that platinum(IV) chloride was not added to the coating composition in Comparative Example 1, and 0.482 mmol of praseodymium(III) chloride (PrCl.sub.3) was added instead of the cerium precursor.

[0072] Molar ratios of components of electrode coating layers prepared in the examples and the comparative examples are summarized in Table 1 below.

TABLE-US-00001 TABLE 1 Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 1 Example 2 Example 3 Example 4 Ru 2.41 2.41 2.41 2.41  2.41 2.41 2.41 2.41  2.41 2.41  Yb 0.482 0.241 0.482 0.241 0.1205 0.3615 — — — — Pt 0.1928 0.1928 — — 0.1928 0.1928  0.1928 —  0.1928 — Ce — 0.241 — 0.241 0.3615 0.1205 0.482 0.482 0.241 — Pr — — — — — — — — 0.241 0.482

EXPERIMENTAL EXAMPLE 1

SEM-EDX Analysis of Coating Layer of Electrode

[0073] Components of the electrode coating layers prepared in Example 2 and Comparative Example 1 were analyzed using scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX), and the results thereof are presented in Table 2 below.

TABLE-US-00002 TABLE 2 Ni (wt %) Ru (wt %) Ce (wt %) Pt (wt %) Yb (wt %) Example 2 10.16 43.27 12.88 12.08 21.62 Comparative 24.83 42.14 15.21 15.14 — Example 1

[0074] From the above results, in Example 2 in which the ytterbium precursor was included in the coating composition, the ytterbium component smoothly formed the electrode coating layer, but, with respect to the comparative example in which the coating was performed with the coating composition not including the ytterbium precursor, it was confirmed that no ytterbium component was detected in the electrode coating layer.

EXPERIMENTAL EXAMPLE 2

Performance Check of the Prepared Electrodes for Electrolysis

[0075] In order to confirm performances of the electrodes prepared in the examples and the comparative examples, a cathode voltage measurement test was performed using half cells in chlor-alkali electrolysis. A 32% NaOH aqueous solution was used as an electrolyte, a platinum (Pt) wire was used as a counter electrode, and a Hg/HgO electrode was used as a reference electrode. After the prepared electrode was put in the electrolyte, the electrode was activated at a constant current density of −0.62 A/cm.sup.2 for 1 hour, and the performance of each electrode was then compared with a potential value in the first hour. The results thereof are summarized in Table 3 below.

TABLE-US-00003 TABLE 3 Comparative Comparative Comparative Comparative Category Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 1 Example 2 Example 3 Example 4 Cathode −1.075 −1.061 −1.076 −1.072 −1.071 −1.059 −1.092 −1.104 −1.102 −1.136 potential (unit: V)

[0076] From the above results, it was confirmed that an effect of improving overvoltage appeared when the ytterbium oxide was further included in the coating layer. Specifically, when the ytterbium oxide was included in the coating layer, it was confirmed that an electrode for electrolysis having excellent durability may be achieved while performance degradation was suppressed due to excellent electrical conductivity of the ytterbium oxide.

[0077] Particularly, with respect to Comparative Examples 3 and 4 using praseodymium corresponding to a lanthanide, the same as ytterbium, performances inferior to those of the examples were found, and, among the examples, performance of Example 6, in which ytterbium having excellent electrical conductivity was used at the highest ratio, was particularly excellent. However, with respect to Example 6, since an amount of cerium was relatively small as an amount of the ytterbium was increased, it was inferior to the other examples in terms of durability and it was confirmed that a portion of the coating layer was peeled off after the electrolysis process.