Background
Clean energy represented by hydrogen energy is an important means for dealing with current energy crisis and environmental problems, and development and utilization techniques of hydrogen energy are receiving more and more attention. The establishment of energy storage and utilization systems using hydrogen as an energy carrier, and the development of relevant technologies and facilities for hydrogen preparation, storage and energy release are ideal ways to replace the current energy utilization systems using fossil fuels as core energy storage materials. In the hydrogen preparation technology, the water electrolysis technology becomes the most developed and mature hydrogen production process by the advantages of simple principle, high product purity, cleanness, no pollution and the like. However, the energy consumption of hydrogen production by water electrolysis is large, and the current commercial catalysts for hydrogen production by water electrolysis and oxygen production are noble metal catalysts such as iridium oxide, ruthenium oxide, platinum and the like, so that the hydrogen production cost is high.
The core reaction of the electrolytic water process is two spatially independent half-reactions: cathodic reduction Hydrogen Evolution Reaction (HER) and anodic oxidation Oxygen Evolution Reaction (OER). For HER reaction, a noble metal simple substance represented by Pt and a platinum carbon electrode have low overpotential and high stability and are widely used, but the noble metal is high in cost. For the OER reaction, the OER reaction path in the four-electron reaction process is long, the kinetics is slow, the OER reaction path is the main reason of the energy loss of electrocatalytic full-hydrolysis, and the activity of the current commercial noble metal electrodes such as iridium oxide and ruthenium oxide is still poor; and the coated noble metal oxide layer is peeled off and deactivated after long-term use. In addition, precious metal resources are scarce and cost is too high to be applied in large scale, so that the development of cheap, efficient and high-cycle-stability non-precious metal HER and OER electrode materials becomes the key of the water electrolysis hydrogen production technology from the aims of improving energy efficiency and reducing cost.
Among a plurality of non-noble metal electrolytic water catalytic electrode materials, metal oxides, particularly binary metal oxides, are approaching to or even surpassing commercial electrode materials such as noble metals in the aspects of catalytic activity and durability due to the lower cost and adjustable electronic structure of the metal oxides, and have application potential. Patent publication No. CN109231255A reports a method for preparing monodisperse, regular-morphology, controllable-size and component-adjustable multi-metal oxide nanoparticles by using cyclodextrin block polymer as a template agent, but the preparation process is complex, the powder layer is difficult to realize the requirement of industrialized high current density, and the particles fall off and are inactivated after being used for a long time. Patent publication No. CN106929830B reports a method for preparing a metal oxide semiconductor thin-film electrode material with a controllable nano structure by growing iron oxide on the surface of a titanium sheet by a hydrothermal method and then roasting and reducing the iron oxide at a high temperature, but the preparation process is long and is difficult to produce on a large scale. Patent publication No. CN108640165A reports a process for preparing a metal oxide nano-structured composite material by utilizing the synergistic effect of normal-pressure plasma and water, but the problems of high difficulty of the preparation process, difficult batch production and the like greatly limit the application of the composite material in the industrialization of electrolyzed water.
Therefore, the current electrode materials for the electrolysis of water with industrially high current density are still under study.
Disclosure of Invention
Aiming at the problems existing currently, the invention provides a three-dimensional bimetal oxide current collector electrode material and a preparation method thereof by simple oxidative corrosion at room temperature under a water phase. The electrode material has low cost and good stability, is suitable for the application of industrial large-current density electrolytic water, has simple preparation method, and is suitable for mass production,
The invention discloses a three-dimensional bimetal oxide current collector electrode material in a first aspect, which comprises the following components: a three-dimensional conductive current collector substrate; and the active material layer is a bimetallic oxide layer and is anchored on the surface of the three-dimensional conductive current collector substrate. Wherein the anchoring is that the bimetal oxide layer grows on the surface of the three-dimensional conductive current collector substrate through surface chemical reaction, and the bimetal oxide layer and the three-dimensional conductive current collector substrate have chemical bonding effect. Compared with the active material layer coated on the surface of the substrate, the coating is firmer and is not easy to fall off.
Preferably, the thickness of the bimetal oxide layer is 0.05-5 μ M, and the composition is MxNyO·nH2O, wherein M, N is a metal ion and at least one thereof is a transition metal ion, x is 0.05 to 0.90, y is 0.1 to 0.95, and n is 0.3 to 2.0.
Preferably, M is one of V, Cr, Mn or Fe, and N is one of Al, Ti, Fe, Co, Ni, Cu and Zn.
Preferably, the three-dimensional conductive current collector substrate is a three-dimensional skeleton structure material of metal or metal alloy.
Preferably, the three-dimensional conductive current collector substrate is a foamed metal or a metal mesh, the thickness of the three-dimensional conductive current collector substrate is 0.5-5mm, the pore density is 20-500ppi, and the pore diameter is 0.01-0.85 mm. The three-dimensional conductive current collector substrate is preferably a foamed metal; ppi is the number of holes per inch (i.e., pores per inch).
Preferably, the three-dimensional conductive current collector substrate is made of one or more alloy materials of Al, Ti, Fe, Co, Ni, Cu and Zn.
The invention discloses a preparation method of the three-dimensional bimetal oxide current collector electrode material in a second aspect, which comprises the following steps:
(1) placing the three-dimensional conductive current collector substrate in an activating solution for cleaning treatment to remove impurities of an original oxide layer and activate the surface;
(2) and (2) placing the three-dimensional conductive current collector substrate subjected to surface activation in the step (1) into a high-valence metal salt solution for oxidation, and obtaining the three-dimensional bimetal oxide current collector electrode material with the bimetal oxide active material layer after a period of time.
Preferably, the activating solution in step (1) is one or a mixture of two or more of hydrochloric acid, sulfuric acid, deionized water, methanol, ethanol, propanol and acetone, and the cleaning treatment time is 10-100 min.
Preferably, the high-valence metal salt in the step (2) is one of water-soluble salts of pentavalent V, hexavalent Cr, hexavalent Mn, heptavalent Mn or hexavalent Fe; the concentration of the high valence metal salt solution is 0.001-1.0 mol/L; the oxidation is carried out under a sealed condition, and the oxidation time is 6-72 h; the ratio of the high-valence metal salt solution to the three-dimensional conductive current collector substrate is 5-200mL of solution and 1g of solution. The oxidation is performed under sealed conditions in order to maintain the oxidizing power of the higher salt because the opening is decomposed to release oxygen, and the active material layer formed by oxidation on the surface of the substrate is thinner or oxidized more slowly.
The third aspect of the invention discloses the application of the three-dimensional bimetal oxide current collector electrode material in hydrogen and oxygen production by water electrolysis. The application is hydrogen production and oxygen production by water electrolysis under industrial large current density.
The three-dimensional bimetal oxide current collector electrode material obtained by the preparation method can catalyze two half reactions (HER and OER) of water electrolysis at the same time, remarkably reduce the voltage in the processes of hydrogen production and oxygen production by water electrolysis, and can be used for a long time under a high current density, thereby reducing the energy consumption of electrolysis. The electrode material has stable three-dimensional structure and stable chemical property, can be produced in batches and can be repeatedly used.
Preferably, the temperature of the water electrolysis for hydrogen production and oxygen production is room temperature, such as 0-40 ℃, the solution is alkaline, such as pH 8-14, and the solute can be one or more of sodium hydroxide, potassium hydroxide and calcium hydroxide.
The invention has the beneficial effects that:
1. the three-dimensional bimetal oxide current collector electrode material has the double functions of hydrogen production and oxygen production by electrocatalytic decomposition of water, can be used for normal-temperature electrocatalytic full-hydrolysis reaction, and can realize 2000A/m2Current density activity of the electrolyzed water; low cost, high efficiency and good cycling stability.
2. The preparation method is simple, harsh conditions such as acid and alkali, high temperature and the like are avoided, the proportion of the obtained bimetallic oxide is adjustable, and the thickness of the bimetallic oxide layer of the active material layer is controllable.
3. The three-dimensional bimetal oxide current collector electrode material has the advantages of low cost and easy obtainment of raw materials, avoids the use of noble metals, and has equivalent activity to noble metals in the electro-catalytic decomposition of water to produce hydrogen and oxygen under high current density.
4. The active material layer of the three-dimensional bimetal oxide current collector electrode material is anchored on the surface of the three-dimensional conductive current collector substrate. Wherein the anchoring is that the bimetal oxide layer grows on the surface of the three-dimensional conductive current collector substrate through surface chemical reaction, and the bimetal oxide layer and the three-dimensional conductive current collector substrate have chemical bonding effect. Compared with the active material layer coated on the surface of the substrate, the coating is firmer and is not easy to fall off and lose activity.
Detailed Description
The following examples are intended to illustrate the invention, but not to further limit the scope of the invention. The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.
Example 1: preparation of three-dimensional ferronickel bimetal oxide current collector electrode material
Firstly, carrying out surface cleaning and activating treatment on a three-dimensional conductive current collector: 1mm thick, 110ppi open cell density foamed nickel was cut into 1cm x 5cm gauge pieces. Putting the cut foam nickel sheet into 100mL of 1.0mol/L hydrochloric acid, and performing ultrasonic activation treatment for 20 min; then placing the pickled foam nickel sheet into 100mL of deionized water, and carrying out ultrasonic treatment for three times, wherein each time lasts for 10 min; then placing the washed foam nickel sheet into 100mL of absolute ethyl alcohol, and carrying out ultrasonic treatment for three times, wherein each time lasts for 10 min; and then, putting the activated and cleaned foam nickel sheet into a vacuum oven at 60 ℃ for drying for 6 hours. Fig. 1 and 2 are micrographs of the nickel foam before and after activation and cleaning, and it can be seen from fig. 1 and 2 that the three-dimensional pore structure and the special skeleton of the nickel foam after activation are fully preserved; and the surface roughness of the framework after activation is obviously increased.
Preparing a nickel-iron bimetal oxide active material layer: 0.198g of potassium ferrate is dissolved in 20mL of deionized water to obtain 0.05mol/L of an aqueous solution of potassium ferrate. And (3) putting the activated foam nickel sheet into a potassium ferrate solution, sealing and standing for 12h, oxidizing and corroding the foam nickel metal by ferrate ions, and forming a nickel-iron bimetal oxide active material layer on the surface of the foam nickel sheet.
Fig. 3 and 4 are SEM of the resulting three-dimensional nickel-iron bimetal oxide current collector electrode material, wherein fig. 3 is a 2000-fold magnified image of the resulting three-dimensional nickel-iron bimetal oxide current collector electrode material by Scanning Electron Microscope (SEM), and fig. 4 is a 10000-fold magnified image of the three-dimensional nickel-iron bimetal oxide current collector electrode material by Scanning Electron Microscope (SEM). From fig. 3 and fig. 4, it can be seen that the ferronickel bimetallic oxide grows uniformly on the surface of the three-dimensional conductive current collector skeleton, and completely covers the nickel foam. It can be seen from fig. 4 that the thickness of the nickel-iron bimetal oxide layer is below 5 μm.
The obtained three-dimensional ferronickel bimetal oxide current collector electrode material is used for hydrogen production and oxygen production by electrolyzing water, the pH is 13.8, the temperature is 25 ℃, and the overpotential is 498mV, which is shown in Table 1. FIG. 5 is an activity curve, and it can be seen from FIG. 5 that the current density reaches 2000A/m at a voltage of 1.72V2。
Example 2: preparation of three-dimensional aluminum-iron bimetal oxide current collector electrode material
Firstly, carrying out surface cleaning and activating treatment on a three-dimensional conductive current collector: 1.5mm thick, 100ppi open cell density aluminum foam was cut into 2cm x 4cm gauge pieces. Putting the cut foamed aluminum sheet into 100mL of 1.0mol/L hydrochloric acid, and performing ultrasonic activation treatment for 5 min; then placing the foamed aluminum sheet after acid cleaning into 100mL of deionized water, and carrying out ultrasonic treatment for three times, wherein each time lasts for 10 min; then placing the washed foamed aluminum sheet into 100mL of anhydrous acetone, and carrying out ultrasonic treatment for three times, wherein each time lasts for 10 min; and then, putting the activated and cleaned foamed aluminum sheet into a vacuum oven at 60 ℃ for drying for 6 hours.
Growth of the aluminum-iron bimetal oxide active material layer: 0.198g of potassium ferrate is dissolved in 20mL of deionized water to obtain 0.05mol/L of an aqueous solution of potassium ferrate. And (3) placing the activated foamed aluminum sheet into a potassium ferrate solution, sealing and standing the solution for reaction for 6 hours, and oxidizing foamed aluminum metal by ferrate ions to form an aluminum-iron bimetal oxide material layer on the surface.
The three-dimensional aluminum-iron bimetallic oxide current collector electrode material obtained is shown in table 1 for producing hydrogen and oxygen by electrolyzing water.
Example 3: preparation of three-dimensional nickel-manganese bimetal oxide current collector electrode material
Firstly, carrying out surface cleaning and activating treatment on a three-dimensional conductive current collector: foamed nickel of 0.5mm thickness and 80ppi open cell density was cut into 1cm x 3cm gauge pieces. Putting the cut foam nickel sheet into 100mL of 1.0mol/L sulfuric acid, and performing ultrasonic activation treatment for 20 min; then placing the pickled foam nickel sheet into 100mL of deionized water, and carrying out ultrasonic treatment for three times, wherein each time lasts for 5 min; then putting the washed foam nickel sheet into 100mL of acetone/propanol (volume ratio is 1:1) mixed solution, and carrying out ultrasonic treatment for three times, wherein each time is 20 min; and then, putting the activated and cleaned foam nickel sheet into a vacuum oven at 60 ℃ for drying for 6 hours.
Growth of the nickel-manganese double-metal oxide active material layer: 0.632g of potassium permanganate is dissolved in 20mL of deionized water to obtain 0.20mol/L potassium ferrate aqueous solution. And (3) placing the activated foam nickel sheet into a potassium permanganate solution, sealing the solution, standing and reacting for 12 hours, oxidizing foam nickel metal by permanganate ions, and forming a nickel-manganese bimetal oxide material layer on the surface.
The three-dimensional nickel-manganese bimetallic oxide current collector electrode material is used for producing hydrogen and oxygen by electrolyzing water, and the oxygen production is shown in table 1.
Example 4: preparation of three-dimensional nickel-manganese bimetal oxide current collector electrode material
Firstly, carrying out surface cleaning and activating treatment on a three-dimensional conductive current collector: foamed nickel of 0.5mm thickness and 80ppi open cell density was cut into 1cm x 3cm gauge pieces. Putting the cut foam nickel sheet into 100mL of 1.0mol/L sulfuric acid, and performing ultrasonic activation treatment for 20 min; then placing the pickled foam nickel sheet into 100mL of deionized water, and carrying out ultrasonic treatment for three times, wherein each time lasts for 5 min; then putting the washed foam nickel sheet into 100mL of acetone/propanol (volume ratio is 1:1) mixed solution, and carrying out ultrasonic treatment for three times, wherein each time is 20 min; and then, putting the activated and cleaned foam nickel sheet into a vacuum oven at 60 ℃ for drying for 6 hours.
Growth of the nickel-manganese double-metal oxide active material layer: 0.196g of sodium permanganate was dissolved in 10mL of deionized water to obtain a 0.10mol/L aqueous solution of sodium permanganate. And (3) placing the activated nickel foam sheet into a sodium permanganate solution, sealing the solution, standing and reacting for 2 hours, oxidizing the nickel foam metal by permanganate ions, and forming a nickel-manganese bimetal oxide material layer on the surface.
The three-dimensional nickel-manganese bimetallic oxide current collector electrode material is used for producing hydrogen and oxygen by electrolyzing water, and the oxygen production is shown in table 1.
Example 5: preparation of three-dimensional nickel-chromium bimetal oxide current collector electrode material
Firstly, carrying out surface cleaning and activating treatment on a three-dimensional conductive current collector: a2.0 mm thick, 110ppi open cell density nickel foam was cut into 1cm x 3cm gauge pieces. Putting the cut foam nickel sheet into 100mL of 1.0mol/L sulfuric acid, and performing ultrasonic activation treatment for 20 min; then placing the pickled foam nickel sheet into 100mL of deionized water, and carrying out ultrasonic treatment for three times, wherein each time lasts for 5 min; then putting the washed foam nickel sheet into 100mL of acetone/propanol (volume ratio is 1:1) mixed solution, and carrying out ultrasonic treatment for three times, wherein each time is 20 min; and then, putting the activated and cleaned foam nickel sheet into a vacuum oven at 60 ℃ for drying for 6 hours.
Growing the nickel-chromium bimetal oxide active material layer: 0.294g of potassium ferrate was dissolved in 10mL of deionized water to obtain 0.025mol/L of an aqueous solution of potassium dichromate. And (3) placing the activated foam nickel piece into a potassium dichromate solution, sealing and standing the solution for reaction for 72 hours, and oxidizing the foam nickel metal by using dichromate ions to form a nickel-chromium bimetal oxide material layer on the surface.
The three-dimensional nickel-chromium bimetallic oxide current collector electrode material is used for producing hydrogen and oxygen by electrolyzing water, and the oxygen production is shown in table 1.
Example 6: preparation of three-dimensional ferro-manganese bimetal oxide current collector electrode material
Firstly, carrying out surface cleaning and activating treatment on a three-dimensional conductive current collector: a2.0 mm thick foam iron with an open cell density of 100ppi was cut into 1cm x 3cm gauge pieces. Putting the cut foam iron sheet into 100mL of 1.0mol/L sulfuric acid, and performing ultrasonic activation treatment for 20 min; then placing the pickled foam iron sheet into 100mL of deionized water, and carrying out ultrasonic treatment for three times, wherein each time lasts for 5 min; then placing the washed foam iron sheet into 100mL of acetone/propanol (volume ratio is 1:1) mixed solution, and carrying out ultrasonic treatment for three times, wherein each time is 20 min; and then, putting the activated and cleaned foam iron sheet into a vacuum oven at 60 ℃ for drying for 6 hours.
And (3) growing the ferro-manganese double-metal oxide active material layer: 0.392g of sodium permanganate was dissolved in 40mL of deionized water to obtain 0.05mol/L aqueous sodium permanganate solution. And (3) placing the activated foam iron sheet into a sodium permanganate solution, sealing the solution, standing and reacting for 12 hours, oxidizing foam iron metal by permanganate ions, and forming a ferro-manganese bimetal oxide material layer on the surface.
The three-dimensional ferro-manganese bimetallic oxide current collector electrode material is used for producing hydrogen and oxygen by electrolyzing water, and the oxygen production is shown in table 1.
Comparative example 1: the comparative example does not contain a layer of a dual metal oxide material. The preparation method comprises the following steps: 1mm thick, 110ppi open cell density foamed nickel was cut into 1cm x 5cm gauge pieces. Putting the cut foam nickel sheet into 100mL of 1.0mol/L hydrochloric acid, and performing ultrasonic activation treatment for 20 min; then placing the pickled foam nickel sheet into 100mL of deionized water, and carrying out ultrasonic treatment for three times, wherein each time lasts for 10 min; then placing the washed foam nickel sheet into 100mL of absolute ethyl alcohol, and carrying out ultrasonic treatment for three times, wherein each time lasts for 10 min; and then, putting the activated and cleaned foam nickel sheet into a vacuum oven at 60 ℃ for drying for 6 hours. The obtained nickel foam without the bimetallic oxide material layer is then used as an electrode material to electrolyze water to produce hydrogen and oxygen, which are shown in table 1.
Comparative example 2: the active material layer in this comparative example was a commercial noble metal catalyst ruthenium oxide layer. The preparation method comprises the following steps: 1mm thick, 110ppi open cell density foamed nickel was cut into 1cm x 5cm gauge pieces. Putting the cut foam nickel sheet into 100mL of 1.0mol/L hydrochloric acid, and performing ultrasonic activation treatment for 20 min; then placing the pickled foam nickel sheet into 100mL of deionized water, and carrying out ultrasonic treatment for three times, wherein each time lasts for 10 min; then placing the washed foam nickel sheet into 100mL of absolute ethyl alcohol, and carrying out ultrasonic treatment for three times, wherein each time lasts for 10 min; and then, putting the activated and cleaned foam nickel sheet into a vacuum oven at 60 ℃ for drying for 6 hours. Preparing commercially available ruthenium oxide into 5mg/mL suspension, adding a Nafion adhesive with the mass ratio of 5%, dropwise adding the suspension onto the activated and cleaned nickel foam, and drying to obtain the nickel foam loaded noble metal ruthenium oxide layer.
The hydrogen and oxygen production by water electrolysis using nickel foam whose active material layer is a noble metal catalyst ruthenium oxide layer as an electrode material is shown in table 1.
Table 1 shows the conditions and activities of electrocatalytic decomposition of water and overpotential of the three-dimensional bimetallic oxide current collector electrode materials prepared in examples 1-6, and compares them with those of comparative examples 1-2 under the same conditions. It can be seen from table 1 that the three-dimensional bimetallic oxide current collector electrode material of the present invention electrolyzes water with comparable activity to the commercially available noble metal oxide layer (comparative example 2); is much higher than that of the electrode material without the double metal oxide active layer in the comparative example 1 (the overpotential is obviously higher).
Under the same conditions, the comparison of the stability data of the electrolyzed water of the three-dimensional bimetal oxide current collector electrode material prepared in the example 1 and the electrode material of the comparative example 2 is shown in fig. 6, and as can be seen from fig. 6, under the same conditions, the current density of the electrolyzed water of the electrode material of the comparative example 2 is gradually reduced, and the current density is changed to about 50% of the original density after 60000 hours; the current density of the electrode material of example 1 hardly changed after 60000 hours. It was found that the noble metal ruthenium oxide layer of the active material layer on the surface of the electrode material of comparative example 2 was gradually exfoliated and deactivated, whereas the electrode material of example 1 did not. The active material layer of the embodiment 1 is anchored on the surface of the foamed nickel, is firmer, is not easy to fall off and has good stability.
Table 1 comparison of activity of three-dimensional bimetallic oxide current collector electrode materials of examples 1-6 with inactive layers, and commercially available noble metal ruthenium oxide layers
Adsorbent and process for producing the same
|
pH of electrolyte
|
Electrolysis temperature/. degree.C
|
2000A/m2Lower overpotential (mV)
|
Example 1
|
13.7
|
25
|
498
|
Example 2
|
13.7
|
25
|
493
|
Example 3
|
13.7
|
25
|
670
|
Example 4
|
13.7
|
25
|
715
|
Example 5
|
13.7
|
25
|
495
|
Example 6
|
13.7
|
25
|
521
|
Comparative example 1
|
13.7
|
25
|
980
|
Comparative example 2
|
13.7
|
25
|
501 |