CN114752971B

CN114752971B - Preparation method of coated titanium anode with high electrolytic durability

Info

Publication number: CN114752971B
Application number: CN202210371514.2A
Authority: CN
Inventors: 冯庆; 柴作强; 郝小军; 闫爱玲; 贾波
Original assignee: Xian Taijin Xinneng Technology Co Ltd
Current assignee: Xian Taijin Xinneng Technology Co Ltd
Priority date: 2022-04-11
Filing date: 2022-04-11
Publication date: 2023-03-28
Anticipated expiration: 2042-04-11
Also published as: CN114752971A

Abstract

The invention discloses a preparation method of a coating titanium anode with high electrolysis durability, which comprises the following steps of S1: pretreating the surface of a titanium substrate; s2: the upper surface and/or the lower surface of the titanium substrate after the S1 treatment is/are treated by laserSequentially preparing a first middle layer M1 and a second middle layer M2 by an additive preparation technology; s3: coating and sintering the surface of the titanium substrate treated in the step S2 to prepare a first catalyst layer C1; s4: coating and sintering the surface of the C1 treated in the step S3 to prepare a second catalyst layer C2; s5: repeating the alternation of S3 and S4 until the total thickness of the catalytic coating coated by the C1 and the C2 is 2-10 um. According to the invention, by adopting the laser additive manufacturing method, a continuous, uniform and compact intermediate layer is formed between the base material and the catalyst layer, so that the service life of the anode is greatly prolonged; the method adopts the mode of alternately coating the iridium-tantalum coating and the ruthenium-iridium-titanium coating, and replaces part of iridium with ruthenium, thereby reducing the comprehensive cost of the coating; irO is maintained ₂ Corrosion resistance, ruO ₂ The high activity and low voltage of the titanium anode can obviously improve the comprehensive performance of the coating titanium anode.

Description

Preparation method of coated titanium anode with high electrolysis durability

Technical Field

The invention relates to the technical field of electrodes, in particular to a preparation method of a coating titanium anode with high electrolytic durability.

Background

The titanium anode, also known as a dimensionally stable electrode (DSA), is composed of a metallic titanium substrate and a metal oxide coating having electrocatalytic activity. The oxide coating generally consists of an active component acting as a catalyst and an inert component acting as a stabilizing coating structure, and is mainly a mixture of iridium oxide and tantalum oxide. Because the coating titanium anode has large current density (7000A/m) when used in the copper foil electrolysis industry ² Above), the process conditions are severe. When the anode is used for more than 2000h cumulatively, the surface catalytic layer is not completely failed, and a continuous TiO layer is formed between the catalytic layer and the base material in the partial area of the anode plate ₂ The insulating layer obstructs the conduction of electrons, causes the increase of oxygen evolution potential, finally causes the local non-plating of the green foil, has large gram weight deviation and high energy consumption, and the anode is judged to be invalid, thereby seriously influencing the service life of the anode. The passivation of the substrate caused by oxygen permeation can be effectively relieved by introducing an intermediate layer between the substrate and the catalytic layerAnd (4) a chemical phenomenon.

In the prior art, the intermediate layer is prepared mainly by a thermal decomposition method, and the prepared intermediate layer has the defects of poor continuity and poor compactness due to the difference of pretreatment, so that the phenomenon of local passivation of a base material cannot be completely solved. In addition, with the continuous increase of the price of noble metal iridium, the cost problem becomes an obstacle for the use of iridium tantalum anodes in the copper foil electrolysis industry. Meanwhile, under the guidance of national double-control policy, the development of high-activity low-voltage anodes and the reduction of the energy consumption of the anodes are urgent matters.

Disclosure of Invention

The invention aims to provide a preparation method of a coated titanium anode with high electrolytic durability, so as to overcome the defects of compactness of an anode intermediate layer, anode cost and use voltage in the prior art.

The technical scheme adopted by the invention for solving the technical problem is as follows: a preparation method of a coated titanium anode with high electrolysis durability comprises a titanium substrate T, a first middle layer M1, a second middle layer M2, a first catalytic layer C1 and a second catalytic layer C2; the preparation method comprises the following steps:

s1: carrying out surface pretreatment on the titanium substrate, wherein the pretreatment comprises sand blasting, acid etching and surface cleaning;

s2: sequentially preparing a first middle layer M1 and a second middle layer M2 on the upper surface and/or the lower surface of the titanium substrate treated in the step S1 by a laser additive preparation technology;

s3: coating and sintering the titanium matrix surface treated by the S2 by a thermal decomposition method to prepare a first catalyst layer C1;

s4: coating and sintering the surface of the first catalyst layer C1 treated in the step S3 to prepare a second catalyst layer C2;

s5: and repeating the alternating steps S3 and S4 until the total thickness of the catalytic coatings alternately coated on the first catalytic layer C1 and the second catalytic layer C2 reaches 2-10 um.

Further, in the step S1, the surface roughness Ra of the pretreated titanium substrate is 7-10 μm.

Further, in the step S2, the first intermediate layer M1 prepared by the laser additive manufacturing technique is a titanium alloy deposition layer, the thickness of the first intermediate layer M1 is 0.5 to 2.5um, ti powder forming the first intermediate layer M1 is prepared by an argon atomization method, and the powder particle size is 50 to 250 mesh.

Furthermore, in the step S2, a second intermediate layer M2 is prepared on the surface of the first intermediate layer M1 by a laser additive technology, the second intermediate layer M2 is a tantalum deposition layer, the thickness of the second intermediate layer M2 is 0.5 to 3um, ta powder forming the tantalum deposition layer is prepared by an argon atomization method, the powder particle size is 50 to 250 meshes, and the tantalum raw material is 99.9% tantalum powder.

Further, in step S3, the first catalytic layer C1 is an iridium tantalum system, and contains IrO as a main component ₂ And Ta ₂ O ₅ Wherein the iridium accounts for 60 to 90 percent of the total mole percentage of the iridium tantalum metal element; the iridium source is one or more of chloroiridic acid and iridium trichloride hydrate, and the tantalum source is one or more of tantalum n-butyl alcohol, tantalum ethanol and tantalum butanediol.

Furthermore, in the step S3, the first catalyst layer C1 is prepared by one or more coating and sintering processes, and the loading amount of Ir coated in each coating process is 0.5-3 g m ^-2 The sintering temperature is 490-530 ℃, and the sintering time is adjusted to 10-60 min.

Further, in the step S4, the second catalytic layer C2 is a ruthenium iridium titanium system, and the main component is RuO ₂ 、IrO ₂ And TiO ₂ Wherein, the mole percentage of ruthenium in the total amount of metal elements is 10-40%, and the mole percentage of iridium in the total amount of metal elements is 1-15%; the ruthenium source is one or more of ruthenium trichloride and chlororuthenic acid, and the titanium source is one or more of butyl titanate and titanium tetrachloride.

Furthermore, in the step S4, the second catalytic layer C2 is prepared by coating and sintering one or more times, and the loading amount of Ru coated each time is 0.2-2 gm ^-2 The sintering temperature is 420-510 ℃, and the sintering time is adjusted to 10-60 min.

Further, in the steps S3 and S4, the organic solvent in the dope for preparing the first catalytic layer C1 and the second catalytic layer C2 is one or more of ethylene glycol, n-butanol, absolute ethanol, and butanediol.

Further, in the step S5, the catalytic coating may be two layers, i.e. C1C2; or multilayer, according to the formula of C1C2C1C2 \8230, C2 is alternatively coated at intervals; and when the catalytic coating meets the thickness requirement, coating the first catalytic layer C1 for the last time, and preserving the heat for 30-120 min to finish the preparation of the catalytic coating.

The invention has the beneficial effects that: compared with the prior art, the preparation method of the coating titanium anode with high electrolytic durability provided by the invention has the following advantages:

1) According to the invention, the titanium and tantalum metal intermediate layer is prepared between the catalyst layer and the titanium substrate by adopting a laser additive manufacturing technology, metallurgical bonding is achieved on each interface, and the prepared intermediate layer has high density, good continuity, strong corrosion resistance and higher thermal stability, can effectively prevent the substrate passivation phenomenon caused by oxygen permeation in the oxygen evolution process, and has a good protection effect on the substrate. The intermediate layer of the metal tantalum has good affinity with oxygen, the binding force between the catalytic coating and the intermediate layer can be effectively improved, and the prepared catalytic coating has good electrochemical stability. In addition, compared with a semiconductor oxide intermediate layer, the metal tantalum intermediate layer has higher electronic conductivity, and the prepared anode has low voltage characteristic;

2) According to the invention, the catalyst layer is arranged to comprise the multi-element catalyst layer units which are stacked from inside to outside, the catalyst layer C1 is an iridium-tantalum coating, the catalyst layer C2 is a ruthenium-iridium-titanium coating, and the two catalyst layer units are alternately coated, so that part of iridium is replaced by ruthenium, and the cost is reduced. Next, irO in the catalyst layer C1 ₂ Has good corrosion resistance, and the alternately coated outer catalyst layer C1 can effectively protect RuO in the inner catalyst layer C2 ₂ Whereas RuO in catalytic layer C2 ₂ But also has higher electrocatalytic activity and lower oxygen evolution potential, which is beneficial to improving the electrocatalytic activity of the anode and reducing the cell voltage. Therefore, the two systems of coatings are compounded in a crossing way, so that the price of the anode can be reduced, and the comprehensive electrochemical performance of the coated titanium anode is obviously improved.

Drawings

FIG. 1 is a schematic structural view of a coated titanium anode provided by the present invention.

Figure 2 is a graph comparing the aging life of the anodes prepared in example 1 and comparative example 1.

Fig. 3 is a graph comparing CV curves of electrodes prepared in example 2 and comparative example 2.

FIG. 4 is a graph comparing the aging life of the electrodes prepared in example 2 and comparative example 2.

In FIG. 1, T is a titanium substrate; m1 is a first intermediate layer; m2 is a second intermediate layer; c1 is a first catalytic layer; and C2 is a second catalytic layer.

Detailed Description

The invention is further illustrated by the following specific examples. These examples are intended to illustrate the invention and are not intended to limit the scope of the invention.

Example 1

The embodiment provides a preparation method of a coated titanium anode with high electrolytic durability, which specifically comprises the following steps.

S1: carrying out surface pretreatment on a titanium substrate T

Cutting a titanium substrate T into blocks with specified sizes, carrying out sand blasting treatment by using a mixture of steel grit and brown fused alumina until the surface roughness of the titanium substrate T reaches 7 mu m and Ra of the titanium substrate T is less than 9 mu m, removing a surface oxide layer, etching the titanium substrate T for 2 hours in a slightly-boiling 10% oxalic acid solution, washing the titanium substrate T with deionized water after the etching is finished, and drying the titanium substrate T for later use.

S2: preparation of the intermediate layer

Forming a first intermediate layer M1 of 1um on a pretreated titanium substrate T by a laser additive manufacturing method, wherein the first intermediate layer M1 is a titanium alloy deposition layer, and the main laser forming technological parameters are laser power 1600W and scanning speed 6mm s ^-1 And the powder feeding speed is 8g min ^-1 . Then a second middle layer M2 with the thickness of 2um is deposited on the surface of the first middle layer M1, the second middle layer M2 is a tantalum deposition layer, and the main process parameters of laser forming are laser power 2700W and scanning speed 8mm s ^-1 And powder feeding speed of 6.5g min ^-1 And finishing the preparation of the intermediate layer.

S3: preparation of catalytic layer

First catalyst layer C1 2g of chloroiridic acid and 4.6g of tantalum pentachloride n-butanol solution were weighed out and dissolved in 40mL of n-butanol, and mechanically stirred for 2h. And then coating the coating liquid on the substrate processed in the step S2, naturally airing, and sintering in a muffle furnace at 500 ℃ for 20min. The above-mentioned coating and sintering process was repeated 5 times.

Second catalyst layer C2: 4g of ruthenium trichloride, 12g of butyl titanate and 0.42g of chloroiridic acid are weighed and dissolved in 75mL of n-butanol, and the mixture is stirred for 1 hour for later use. And then uniformly brushing the surface of the first catalyst layer C1 by using a brush, drying, and then placing in a muffle furnace at 460 ℃ for high-temperature sintering for 15min. The above-mentioned brushing process was repeated 3 times.

S5: and then, continuously repeating the coating and sintering process of the first catalyst layer C1 on the basis of the second catalyst layer C2, namely coating the first catalyst layer C1 for the last time according to the sequence of C1C2C1C2C1C2 until the thickness of the catalyst layer reaches 6um, and preserving the heat in a muffle furnace at 500 ℃ for 1.5 hours to finish the preparation of the anode.

Example 2

S1: carrying out surface pretreatment on a titanium substrate T

Cutting the titanium matrix T by 100 x 100mm, performing sand blasting treatment by using steel grit until the surface roughness of the titanium matrix T reaches 8 mu m and Ra is more than 10 mu m, etching the titanium matrix T in a slightly boiling 5% oxalic acid solution for 3.5h, washing the titanium matrix T with deionized water after etching is finished, and drying the titanium matrix T for later use.

S2: preparation of the intermediate layer

A first intermediate layer M1 of 2.5um is formed on a pretreated titanium substrate T through a laser additive manufacturing method, the first intermediate layer M1 is a titanium alloy deposition layer, and main laser forming technological parameters are laser power 1600W and scanning speed 6mm s ^-1 And powder feeding speed of 6g min ^-1 . Then a second middle layer M2 with the thickness of 0.5um is deposited on the surface of the first middle layer M1, the second middle layer M2 is a tantalum deposition layer, and the main process parameters of laser forming are laser power 2700W and scanning speed 6.5mm s ^-1 And the powder feeding speed is 8g min ^-1 And completing the preparation of the intermediate layer.

S3: preparation of catalytic layer

First catalytic layer C1 g of iridium trichloride and 0.39g of tantalum pentachloride n-butanol solution were weighed out and dissolved in 25mL of n-butanol, and mechanically stirred for 2 hours. And then coating the coating liquid on the substrate treated in the step S2, naturally airing, and sintering in a muffle furnace at 520 ℃ for 10min. The above-mentioned coating and sintering process was repeated 2 times.

Second catalyst layer C2: 1g of ruthenium trichloride, 5.3g of butyl titanate and 0.2g of chloroiridic acid are weighed and dissolved in 20mL of n-butanol, and the mixture is stirred for 2 hours for later use. Then, a brush is uniformly coated on the surface of the first catalyst layer C1, and after drying, the first catalyst layer is placed in a muffle furnace at 450 ℃ for high-temperature sintering for 20min. The above-mentioned brushing process was repeated 4 times.

S5: and then, continuously repeating the coating and sintering process of the first catalyst layer C1 on the basis of the second catalyst layer C2, namely coating the first catalyst layer C1 for the last time according to the sequence of C1C2C1C2C1C2, and preserving heat for 1h in a muffle furnace at 510 ℃ to finish the preparation of the anode.

Example 3

S1: the surface pretreatment of the titanium substrate T is completely consistent with that of the embodiment 1;

s2: preparation of the intermediate layer

The thickness of the first middle layer M1 is 0.5um, the thickness of the second middle layer M2 is 3um, and the preparation process parameters are consistent with those of the embodiment 2;

s3: preparation of the catalytic layer

First catalytic layer C1: weighing 2g of iridium trichloride and 1.5g of tantalum pentachloride n-butyl alcohol solution, dissolving in 20mL of n-butyl alcohol, mechanically stirring for 2h, and keeping the sintering coating process consistent with that of the embodiment 2;

second catalyst layer C2: weighing 1.5g of iridium trichloride, 10g of butyl titanate and 0.4g of chloroiridic acid, dissolving in 100mL of ethylene glycol, mechanically stirring for 4 hours, and keeping the sintering coating process consistent with that of embodiment 1;

s5: in keeping with example 1.

Comparative example 1

The comparative example provides a preparation method of a coated titanium anode, which specifically comprises the following steps.

S1: the titanium substrate surface pretreatment was completely in accordance with example 1;

s2: preparation of the intermediate layer

0.04mol of butanediol tantalum is dissolved in 250mL of butanediol solution to prepare a precursor solution of the intermediate protective layer. Coating the prepared intermediate layer precursor solution on the surface of the titanium substrate prepared in the step S1, and sintering in an air atmosphere at 500 ℃; repeating the coating and sintering for 2 times, and coating for 3 times to obtain a tantalum oxide intermediate layer;

s3, S4 and S5: the procedure for the preparation of the catalytic layer remained completely in accordance with example 1.

Comparative example 2:

S1: the titanium substrate surface pretreatment was completely in accordance with example 2;

s2: the preparation process of the intermediate layer was completely identical to that of example 2;

s3: preparing a catalytic layer: 1.5g of iridium trichloride and 0.59g of tantalum pentachloride n-butanol solution were weighed out and dissolved in 38mL of n-butanol, and mechanically stirred for 2 hours. And then coating the coating liquid on the base material treated in the step S2, naturally airing, and sintering in a muffle furnace at 520 ℃ for 10min. Repeating the brushing and sintering process until the feed liquid is completely brushed, and finally preserving the heat for 1 hour at 510 ℃ in the air atmosphere.

The experimental results are as follows: fig. 2 is a graph comparing the aging life of the anodes prepared in example 1 and comparative example 1, and it can be seen that the enhanced life of the anode prepared in example 1 is 1.6 times that of the anode prepared in comparative example 1, and the anode prepared in example 1 has a lower voltage, which illustrates that the introduction of the alloy interlayer is advantageous to prevent the permeation of oxygen, and the electrochemical stability of the anode is improved while the voltage is reduced. Fig. 4 is an aging life curve of example 2 and comparative example 2, and it can be seen that the reinforcement life of example 2 and comparative example 2 is substantially equivalent. In addition, as can be seen from the CV curves of example 2 and comparative example 2 in fig. 3, the CV curve of the anode prepared in example 2 has a larger area than that of the anode prepared in comparative example 2, indicating that the anode prepared in example 2 has better electrocatalytic activity without a decrease in the life span. In conclusion, the compact continuous interlayer is prepared by the laser additive manufacturing method, and the functional gradient catalytic coating is prepared by cross coating of the iridium-tantalum coating and the ruthenium-iridium-titanium coating, so that the electrocatalytic activity is improved, the cell voltage and the comprehensive cost are reduced, and the electrochemical stability of the coating is greatly improved.

The above embodiments are only for illustrating the present invention and not for limiting the present invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, therefore all equivalent technical solutions also belong to the scope of the present invention, and the protection scope of the present invention should be defined by the claims.

Claims

1. A preparation method of a coated titanium anode with high electrolysis durability is characterized in that the coated titanium anode comprises a titanium substrate T, a first middle layer M1, a second middle layer M2, a first catalytic layer C1 and a second catalytic layer C2; the preparation method comprises the following steps:

s2: sequentially preparing a first middle layer M1 and a second middle layer M2 on the upper surface and/or the lower surface of the titanium substrate treated by the step S1 by a laser additive preparation technology;

s3: coating and sintering the surface of the titanium substrate treated by the S2 by a thermal decomposition method to prepare a first catalyst layer C1;

s5: repeating the alternating steps S3 and S4 until the total thickness of the catalytic coatings alternately coated on the first catalytic layer C1 and the second catalytic layer C2 reaches 2-10 μm;

in the step S2, the first intermediate layer M1 prepared by the laser material increasing technology is a titanium alloy deposition layer, the thickness of the first intermediate layer M1 is 0.5-2.5 mu M, ti powder forming the first intermediate layer M1 is prepared in an argon atomization mode, and the powder granularity is 50-250 meshes; in the step S2, a second intermediate layer M2 is prepared on the surface of the first intermediate layer M1 by a laser additive technology, the second intermediate layer M2 is a tantalum deposition layer, the thickness of the second intermediate layer M2 is 0.5 to 3 μ M, ta powder forming the tantalum deposition layer is prepared by argon atomization, the powder particle size is 50 to 250 meshes, and the tantalum raw material is 99.9% tantalum powder;

in the step S3, the first catalyst layer C1 is an iridium-tantalum system, and contains IrO as a main component ₂ And Ta ₂ O ₅ Wherein the iridium accounts for 60 to 90 percent of the total mole percentage of the iridium tantalum metal element; the iridium source is one or more of chloroiridic acid and iridium trichloride hydrate, and the tantalum source is one or more of tantalum n-butyl alcohol, tantalum ethanol and tantalum butanediol; in the step S3, the first catalyst layer C1 is prepared by one or more times of coating and sintering, and the loading amount of Ir coated in each time is 0.5-3 g.m ^-2 The sintering temperature is 490-530 ℃, and the sintering time is adjusted to 10-60 min;

in the step S4, the second catalyst layer C2 is a ruthenium iridium titanium system, and the main component of the second catalyst layer is RuO ₂ 、IrO ₂ And TiO ₂ Wherein, the mole percentage of ruthenium in the total amount of the metal elements is 10 to 40 percent, and the mole percentage of iridium in the total amount of the metal elements is 1 to 15 percent; the ruthenium source is one or more of ruthenium trichloride and chlorine ruthenate, and the titanium source is one or more of butyl titanate and titanium tetrachloride; in the step S4, the second catalyst layer C2 is prepared by coating and sintering once or multiple times, and the loading capacity of Ru coated each time is 0.2-2 g.m ^-2 The sintering temperature is 420-510 ℃, and the sintering time is adjusted to 10-60 min;

in step S5, the catalytic coating may be 2 layers, i.e., C1C2; or multiple layers, according to C1C2C1C2 \8230: \8230:c2 is alternatively coated at intervals; and when the catalytic coating meets the thickness requirement, coating the first catalytic layer C1 for the last time, and preserving the heat for 30-120 min to finish the preparation of the catalytic coating.

2. A method of making a coated titanium anode having high electrolytic durability as claimed in claim 1 wherein: in the step S1, the surface roughness Ra of the pretreated titanium substrate is required to be 7-10 mu m.

3. The method for preparing a coated titanium anode having high electrolytic durability as claimed in claim 1, wherein: in the steps S3 and S4, the organic solvent in the masking liquid for preparing the first catalytic layer C1 and the second catalytic layer C2 is one or more of ethylene glycol, n-butanol, absolute ethanol, and butanediol.