阅读说明：本技术 一种氧化钴纳米薄片析氯电极及其制备方法与应用 (Cobalt oxide nano-sheet chlorine evolution electrode and preparation method and application thereof ) 是由 王朋 黄柏标 王泽岩 张晓阳 刘媛媛 郑昭科 张倩倩 程合锋 于 2021-01-14 设计创作，主要内容包括：本发明涉及一种氧化钴纳米薄片析氯电极及其制备方法与应用。包括钛基底和生长在钛基底上的氧化钴纳米薄片,氧化钴化学式为Co-3O-4,氧化钴的晶体结构为立方相,氧化钴在钛基底上生长,相邻的纳米片穿插相接。氧化钴纳米薄片的厚度为20-30nm。制备方法：将金属钛网与钴盐溶液混合进行电沉积反应,在钛网的表面沉积得到氢氧化钴(Co(OH)-2/Ti)；然后将Co(OH)-2/Ti进行煅烧得到Co-3O-4/Ti电极。优异的电催化效率,在析氢领域中具有较好的应用前景。(The invention relates toA cobalt oxide nano-sheet chlorine evolution electrode and a preparation method and application thereof. Comprises a titanium substrate and a cobalt oxide nano-sheet growing on the titanium substrate, wherein the cobalt oxide has a chemical formula of Co 3 O 4 The crystal structure of the cobalt oxide is cubic phase, the cobalt oxide grows on the titanium substrate, and the adjacent nano sheets are connected in an interpenetration mode. The thickness of the cobalt oxide nano-flake is 20-30 nm. The preparation method comprises the following steps: mixing the metal titanium net with cobalt salt solution to carry out electrodeposition reaction, and depositing on the surface of the titanium net to obtain cobalt hydroxide (Co (OH) 2 a/Ti); then mixing Co (OH) 2 Calcining Ti to obtain Co 3 O 4 a/Ti electrode. Excellent electrocatalysis efficiency and better application prospect in the field of hydrogen evolution.)

1. A cobalt oxide nano-sheet chlorine evolution electrode is characterized in that: comprises a titanium substrate and a cobalt oxide nano-sheet growing on the titanium substrate, wherein the cobalt oxide has a chemical formula of Co₃O₄The crystal structure of the cobalt oxide is cubic phase, the cobalt oxide grows on the titanium substrate, and the adjacent nano sheets are connected in an interpenetration mode.

2. The cobalt oxide nanosheet chlorine evolving electrode of claim 1 wherein: the thickness of the cobalt oxide nano-flake is 20-30 nm.

3. The method for preparing a cobalt oxide nanosheet chlorine evolution electrode of claim 1 or 2, wherein: the method comprises the following specific steps:

mixing a metal titanium mesh with a cobalt salt solution to carry out an electrodeposition reaction, and depositing on the surface of the titanium mesh to obtain cobalt hydroxide;

then mixing Co (OH)₂Calcining Ti to obtain Co₃O₄a/Ti electrode.

4. The method for preparing a cobalt oxide nanosheet chlorine evolving electrode of claim 3, wherein: the solute cobalt salt in the cobalt salt solution is cobalt nitrate or cobalt chloride, cobalt sulfate.

5. The method for preparing a cobalt oxide nanosheet chlorine evolving electrode of claim 3, wherein: the concentration of the cobalt salt solution is 0.05-0.15 mol/L.

6. The method for preparing a cobalt oxide nanosheet chlorine evolving electrode of claim 3, wherein: the voltage is controlled to be-0.8 to-0.7V in the electrodeposition process, and the amount of deposited electric charge is 2.0 to 4.0C/cm²。

7. The method for preparing a cobalt oxide nanosheet chlorine evolving electrode of claim 3, wherein: the calcination temperature is 200-400 ℃, the calcination time is 1-3 h, and the temperature rise speed is 4-6 ℃/min; preferably 250-350 ℃; further preferably 280-320 ℃; more preferably 300 deg.c.

8. The method for preparing a cobalt oxide nanosheet chlorine evolving electrode of claim 3, wherein: before the metal titanium mesh is subjected to the electrodeposition reaction, cleaning the surface of the titanium mesh to remove organic matters on the surface;

preferably, the cleaning method uses acetone, ethanol and water for ultrasonic cleaning; further preferably, the ultrasonic time is 20-40 min and the frequency is 30-50 KHz.

9. Use of the cobalt oxide nanosheet chlorine evolving electrode of claim 1 or 2 in the chlor-alkali industry or in photoelectrocatalysis.

10. The use of claim 9, wherein: the application of the compound as an anode in the electrocatalytic decomposition of seawater or saturated sodium chloride solution for chlorine evolution;

preferably, the electrolyte is an acidic chlorine evolution electrolyte or a strong base oxygen evolution electrolyte.

Technical Field

The invention belongs to the technical field of energy and electrochemistry, and particularly relates to a cobalt oxide nanosheet chlorine evolution electrode and a preparation method and application thereof.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

Chlorine, hydrogen and sodium hydroxide are industrially produced by electrolysis of saturated sodium chloride solution and are used as raw materials to produce a series of chemical products, this process is called chlor-alkali industry for short, which is one of the most basic chemical industries. These products have a wide range of applications, in addition to the chemical industry itself, also in the petrochemical industry, the metallurgical industry, the light industry, the textile industry and the utilities industry. The common chlor-alkali process at present mainly comprises a mercury electrolytic cell method, a double electrolytic cell method, a diaphragm method and the like, wherein the latter method is widely applied due to the advanced high efficiency, green and safety. The basic principle is that the anode chamber generates oxidation reaction: 2Cl^--2e^-＝Cl₂× (anodic reaction); reduction reaction in the cathode chamber: 2H⁺+2e^-＝H₂× (cathode reaction); and (3) total reaction: 2NaCl +2H₂O ═ 2NaOH + Cl (power on)₂↑+H₂At present, the industrial production anode mainly focuses on coating noble metal oxides such as ruthenium, iridium and the like on the surface of a titanium sheet or a titanium mesh; the industrial production cathode is mainly an inexpensive carbon steel mesh coated with a nickel layer. Ruthenium oxide and iridium oxide are the preferred materials for commercial chlorine evolution electrodes due to their low overpotential and high chlorine evolution selectivity, but the electrodes are expensive to produce due to their rare earth content. Therefore, how to prepare the chlorine-separating anode with high efficiency and low cost is always the core problem of the chlor-alkali industry.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a cobalt oxide nanosheet chlorine evolution electrode and a preparation method and application thereof.

In order to solve the technical problems, the technical scheme of the invention is as follows:

in a first aspect, a cobalt oxide nanosheet chlorine evolution electrode comprises a titanium substrate and a cobalt oxide nanosheet grown on the titanium substrate, wherein the cobalt oxide has a chemical formula of Co₃O₄The crystal structure of the cobalt oxide is cubic phase, the cobalt oxide grows on the titanium substrate, and the adjacent nano sheets are connected in an interpenetration mode.

The cobalt oxide nano-flake obtained by growing on the titanium substrate is a product with a special structure and a special phase. Has the advantages of low overpotential and high chlorine evolution selectivity, and solves the problem of dependence on ruthenium oxide and iridium oxide. Can be used for chlorine evolution and oxygen evolution.

In some embodiments of the invention, the cobalt oxide nanoflakes have a thickness of 20-30 nm. The flakes have a nanometer size.

In a second aspect, the preparation method of the cobalt oxide nanosheet chlorine evolution electrode comprises the specific steps of:

mixing the metal titanium net with cobalt salt solution to carry out electrodeposition reaction, and depositing on the surface of the titanium net to obtain cobalt hydroxide (Co (OH)₂/Ti)；

Then mixing Co (OH)₂Calcining Ti to obtain Co₃O₄a/Ti electrode.

In some embodiments of the invention, the solute cobalt salt in the cobalt salt solution is cobalt nitrate or chloride, cobalt sulfate, or the like.

In some embodiments of the present invention, the concentration of the cobalt salt solution is 0.05 to 0.15 mol/L.

In some embodiments of the present invention, the control voltage is-0.8 to-0.7V and the amount of deposited charge is 2.0 to 4.0C/cm during electrodeposition²。

The concentration of cobalt salt and the deposition voltage directly affect the deposition rate of Co, and the lower the concentration, the smaller the deposition voltage, the slower the deposition rate, and thus the higher the resulting electrode efficiency.

In some embodiments of the invention, the calcination temperature is 200-; preferably 250-350 ℃; further preferably 280-320 ℃; more preferably 300 deg.c. In the above temperature range, a lower overpotential is obtained.

In some embodiments of the present invention, before the metal titanium mesh is subjected to the electrodeposition reaction, the surface of the titanium mesh is cleaned to remove organic substances on the surface. The cleaning method uses acetone, ethanol and water for ultrasonic cleaning. Preferably, the ultrasonic time is 20-40 min and the frequency is 30-50 KHz.

In a third aspect, the cobalt oxide nano-flake chlorine evolution electrode is applied to the chlor-alkali industry.

In some embodiments of the invention, the use of the composition as an anode in the electrocatalytic decomposition of seawater or saturated sodium chloride solution for chlorine evolution.

Preferably, the electrolyte is an acidic chlorine evolution electrolyte or a strong base oxygen evolution electrolyte.

One or more technical schemes of the invention have the following beneficial effects:

(1) the prepared cobalt oxide nano-sheet electrode shows excellent electrocatalytic efficiency, can be widely applied to the fields of photocatalysis and photoelectrocatalysis as an oxygen production promoter, and can be prepared into an electrodeThe seawater or saturated sodium chloride solution is decomposed by electrocatalysis to generate hydrogen, chlorine, sodium hydroxide and other industrial raw materials. Experimental research shows that the initial potential of the chlorine evolution reaction of the cobalt oxide nano-sheet is about 1.46V (vs. RHE), and the current density is 10mA/cm²Potential at time 1.51V (vs. rhe); while commercial titanium anodes (RuO)₂/IrO₂) The initial potential of the chlorine evolution reaction was about 1.49V (vs. RHE) at a current density of 10mA/cm²Potential at 1.53V (vs. rhe); compared with the chlorine evolution electrode prepared by the invention, the catalytic activity is more excellent.

(2) The prepared cobalt oxide nano-sheet electrode is subjected to chlorine evolution reaction for 4 days in a three-electrode system (cobalt oxide is used as a working electrode, a platinum sheet is used as a counter electrode, and Ag/AgCl is used as a reference electrode), and then 50mA/cm²The current density of (2) is not significantly reduced although it fluctuates, and still has very high catalytic activity. In summary, cobalt oxide titanium anodes, which are equally excellent in stability and catalytic activity and low in cost, have a wide commercial prospect as compared to high-cost commercial titanium anodes.

(2) The preparation method has the advantages of very simple conditions, no pollution and low cost, and shows the potential of large-scale industrial application.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the invention and not to limit the invention.

FIG. 1 is a schematic diagram of a cobalt oxide nanosheet chlorine evolving electrode prepared in example 1.

Fig. 2 is the XRD patterns corresponding to the cobalt oxide nanosheet chlorine evolving electrode prepared in example 1 and a commercial titanium electrode.

Fig. 3 is SEM images corresponding to the cobalt oxide nanosheet chlorine evolving electrode and the commercial titanium electrode prepared in example 1.

Fig. 4 is a graph of current density-voltage (LSV) relationship for cobalt oxide nanoflake chlorine-evolving electrodes prepared in example 1 and commercial titanium electrodes.

Fig. 5 is a current density-voltage (LSV) relationship graph of the cobalt oxide nanosheet chlorine-analyzing electrode prepared in examples 1-4.

FIG. 6 shows the stability test of current density-time (it) of the cobalt oxide nanosheet chlorine evolving electrode prepared in example 1.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise. The invention will be further illustrated by the following examples

Example 1

A preparation method of a cobalt oxide nano-sheet chlorine evolution electrode easy for industrial production comprises the following steps:

(1) ultrasonic cleaning of a metal titanium mesh:

cutting with scissors to obtain 1.0cm × 2.0cm metal titanium mesh, ultrasonic cleaning with acetone, ethanol and deionized water for 30 min, and placing in ethanol solvent.

(2) Electro-deposition of cobalt hydroxide flakes:

firstly, 0.1mol/L cobalt nitrate solution is prepared, and cobalt hydroxide is deposited on the substrate by controlling the deposition voltage and the deposition charge quantity. The deposition voltage is controlled at-0.75V (vs. Ag/AgCl), and the deposition charge amount is controlled at 3.0C/cm². To obtain Co (OH)₂/Ti。

(3) Calcining to obtain Co₃O₄A Ti electrode:

mixing the Co (OH) prepared in the step (2)₂The Ti is put into a muffle furnace, and the heating rate is set toKeeping the temperature at 300 ℃ for 2.0 hours at the temperature of 5 ℃/min in the air atmosphere, naturally cooling, and taking out a sample to obtain Co₃O₄a/Ti electrode.

Example 2

The preparation method is the same as that of example 1, except that: variation of annealing temperature in step (3): at 250 ℃ to obtain a mixture.

Example 3

The preparation method is the same as that of example 1, except that: variation of annealing temperature in step (3): at 350 ℃.

Example 4

The preparation method is the same as that of example 1, except that: variation of annealing temperature in step (3): at 400 ℃.

Example 5

The preparation method is the same as that of example 1, except that: the concentration of the cobalt nitrate solution was 0.15 mol/L.

Schematic diagram of synthesizing large-size cobalt oxide chlorine evolution electrode:

the cobalt oxide chlorine evolution electrode with large size (10cm x 10cm) is tried to be expanded and successfully prepared by using the examples 1 and 2, the specific steps are shown in figure 1, and the method is proved to be capable of preparing the chlorine evolution electrode with larger size, such as the size of a commercial titanium anode applied in industry: 90cm × 45 cm. As can be seen from FIG. 1, the preparation method of the invention is simple, pollution-free and low in cost, and shows very large commercial application potential. The test materials used were all conventional in the art and commercially available.

Phase testing:

cobalt oxide chlorine evolution electrode and commercial titanium electrode (RuO) prepared in example 1₂/IrO₂) The X-ray diffraction pattern of (a) is shown in fig. 2. As can be seen from the graph (a) in FIG. 2, the diffraction peaks other than the diffraction peak of the base Ti network are similar to RuO₂And IrO₂The standard card is met. As can be seen from the graph (b) in FIG. 2, several weaker diffraction peaks match the standard cobalt oxide card (JCPDS No. 42-1467). Shows that Co is successfully obtained after calcination₃O₄The crystal structure is cubic, but the crystallinity is poor, so that the XRD diffraction peak is weak.

And (3) micro-morphology testing:

cobalt hydroxide flakes, cobalt oxide flakes, and commercial titanium electrode (RuO) prepared in example 1₂/IrO₂) The scanning electron microscope characterization of (a) is shown in fig. 3, and it can be seen from the graph (a) of fig. 3 that the surface of the commercial titanium electrode is flat and smooth. As can be seen from fig. 3 (b), the deposited cobalt hydroxide is interspersed with the nanoflakes. As shown in the graphs (c) and (d) of FIG. 3, the morphology of the cobalt oxide obtained after calcination was consistent with that of cobalt hydroxide, and the thickness of the flake was about 20-30 nm.

Electrocatalytic activity test:

1. the test method comprises the following steps:

the cobalt oxide nanosheet chlorine evolution electrode prepared in examples 1 to 4 was used as a working electrode, the saturated Ag/AgCl electrode was used as a reference electrode, the platinum sheet was used as a counter electrode, the saturated sodium chloride solution containing 0.2mol/L sodium dihydrogen phosphate was used as an acidic chlorine evolution electrolyte, the 1mol/L potassium hydroxide solution was used as a strong base oxygen evolution electrolyte, and the 0.2mol/L sodium dihydrogen phosphate solution was used as an acidic oxygen evolution electrolyte. The prepared electrode was subjected to a Linear Scanning (LSV) test (scanning speed of 5mV/s, iR offset of 90%), a stability test (it) and the like by an electrochemical workstation (shanghai chenhua CHI 600E). The results are shown in FIGS. 4 to 6.

2. And (3) test results:

the current density-voltage (LSV) relationship of the cobalt oxide chlorine evolving electrode prepared in example 1 and the commercial electrode is shown in figure 4,

the current density-voltage (LSV) relationships of the cobalt oxide chlorine evolution electrodes prepared in examples 1 to 4 (different calcination temperatures: 250 ℃, 300 ℃, 350 ℃ and 400 ℃) are shown in FIG. 5,

the stability of the current density versus time (it) of the cobalt oxide chlorine evolving electrode prepared in example 1 is shown in fig. 6.

As can be seen from FIG. 4, the cobalt oxide electrode chlorine evolution reaction initiation potential was about 1.46V (vs. RHE), and the current density was 10mA/cm²Potential at time 1.51V (vs. rhe); while commercial titanium anodes (RuO)₂/IrO₂) The initial potential of the chlorine evolution reaction was about 1.49V (vs. RHE) at a current density of 10mA/cm²Potential at 1.53V (vs. rhe); in contrast, the assay prepared according to the inventionThe chlorine electrode has more excellent catalytic activity. And it can be seen that the chlorine evolving electrode of the present invention compares to a commercial titanium anode (RuO)₂/IrO₂) The potential is lower at the same current density.

The electrode material used in the sodium dihydrogen phosphate electrolyte is inactive and no reaction occurs, so the current is zero.

In different electrolytes, the conductive groups are different and the groups participating in the reaction are also different, so that the curves are very different.

As can be seen from fig. 5, as the annealing temperature increases, the current density in the saturated sodium chloride electrolyte increases and then gradually decreases, and the optimum catalytic activity is achieved under the conditions that the calcination temperature is 300 ℃ and the calcination time is 2 hours.

As can be seen from fig. 6, after the cobalt oxide nanosheet electrode prepared in example 1 undergoes a chlorine evolution reaction for 4 days, the current density fluctuates, but does not decrease significantly, and the cobalt oxide nanosheet electrode still has very high catalytic activity. It is worth noting that the occurrence of fluctuations is attributed to the long-term electrolytic reaction resulting in a change in pH and a drop in liquid level.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.