Preparation method of copper hydroxide / cuprous sulfide nano array

Abstract

The invention provides a preparation method of a copper hydroxide / cuprous sulfide nano array, and belongs to the technical field of nano material preparation, and the prepared Cu (OH) 2 / Cu2S nano array is simple in preparation process, stable in material quality and good in cost benefit. In addition, the overpotential of the prepared Cu (OH) 2 / Cu2S nano array is lower than 174 mV (10 mA cm <-2 >), the HER performance is excellent, the preparation method does not need to use expensive materials and complex devices, and the Cu (OH) 2 / Cu2S nano array has environmental friendliness and can be used for electro-catalytic hydrogen evolution.

Description

Technical Field

[0001] The invention belongs to the technical field of nano material preparation, and specifically relates to a method for preparing a copper hydroxide / cuprous sulfide (Cu(OH)2 / Cu2S) nano array. Background Art

[0002] Nanomaterials refer to materials that have at least one dimension in the nanometer scale (1-100nm) in three-dimensional space or are composed of them as basic units. With the development of society, the development of clean energy is becoming more and more important. Nanostructured electrode materials have a larger surface active area and specific surface area, can fully contact the electrolyte, can make the electrochemical reaction more complete and faster, and become good candidates for the preparation of electrochemical energy storage devices.

[0003] Due to their unique biological, physical and chemical properties, copper-containing nanomaterials have gradually become the preferred materials for designing and constructing electrochemical sensors with multifunctionality and high performance. With the continuous development of nanomaterials, research on their preparation methods and applications has gradually deepened. At present, many methods for preparing copper-containing nanomaterials have been developed, including solution method (Synthesis of different Cu(OH)2and CuO(nanowires, rectangles, seed-, belt-, and sheetlike) nanostructures by simple wet chemical route. J.phys.chem.c 113.9(2009):3409-3418.), precipitation method (CdS nanorods supported copper-nickel hydroxide for hydrogen production under direct sunlight irradiation. Journal of Environmental Chemical Enginnering, 2021, 9(4):105670.) and electrochemical method (A high-performance supercapacitor electrode based on three-dimensional poly-rowed copper hydroxide nanorods on copper foam. Journal of Material Science: Materials in Electronics, 2018, 29:2660-2667.), etc. However, these methods often have problems such as unstable prepared materials, easy detachment from the electrode, high production cost and complex process, which restricts the application of copper-containing nanomaterials in the field of electrochemical materials and devices. Summary of the invention

[0004] In view of the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a method for preparing a Cu(OH)2 / Cu2S nanoarray. The preparation method of the present invention is simple and efficient, and can prepare a Cu(OH)2 / Cu2S nanoarray with excellent electrocatalytic hydrogen evolution performance under environmentally friendly conditions; and the Cu(OH)2 / Cu2S nanoarray prepared by the present invention has been subjected to multiple tests, and the hydrogen production performance remains unchanged, and there is no phenomenon of Cu(OH)2 / Cu2S falling off from the electrode during the test process.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect of the present invention, a method for preparing a Cu(OH)2 / Cu2S nanoarray is provided, comprising the following steps:

[0007] (1) using the cleaned and activated copper foam as a substrate, placing the substrate in an aqueous solution containing NaOH and ammonium persulfate for immersion reaction to prepare a Cu(OH)2 nanoarray precursor;

[0008] (2) heat treating the Cu(OH)2 nanoarray precursor under the protection of an inert gas to obtain a Cu(OH)2 nanoarray;

[0009] (3) The Cu(OH)2 nanoarray is placed in a Na2S aqueous solution for hydrothermal reaction to prepare a Cu(OH)2 / Cu2S nanoarray.

[0010] Preferably, in step (1), the method for cleaning and activating the copper foam is: placing the copper foam in HCl, acetone and ethanol in sequence for surface cleaning and activation for 10-20 minutes each.

[0011] Preferably, in step (1), the aqueous solution contains NaOH (0.05-0.15) g / ml and ammonium persulfate (0.02-0.03) g / ml; and the soaking reaction time is 0.5h-1h.

[0012] Preferably, in step (2), the inert gas is argon.

[0013] Preferably, in step (2), the heat treatment temperature is 280°C-320°C, and the heat treatment time is 4h-8h.

[0014] Preferably, in step (3), the temperature of the hydrothermal reaction is 85°C-95°C, and the time of the hydrothermal reaction is 2h-4h.

[0015] The second aspect of the present invention provides a Cu(OH)2 / Cu2S nanoarray prepared by the above preparation method.

[0016] The third aspect of the present invention provides the use of the above-mentioned Cu(OH)2 / Cu2S nanoarray in electrocatalytic hydrogen evolution.

[0017] Beneficial effects of the present invention:

[0018] (1) The method for preparing the Cu(OH)2 / Cu2S nanoarray provided by the present invention is simple and efficient, and does not require the use of expensive materials and complex equipment. The Cu(OH)2 / Cu2S nanoarray with excellent electrocatalytic hydrogen evolution performance can be prepared under environmentally friendly conditions.

[0019] (2) The Cu(OH)2 / Cu2S prepared by the present invention has good stability. After multiple tests, the hydrogen production performance remains basically unchanged; and there is no phenomenon of Cu(OH)2 / Cu2S falling off from the electrode during the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Scanning electron microscope (SEM) images of Cu(OH)2 and Cu(OH)2 / Cu2S prepared in the present invention; wherein AC is the SEM image of the Cu(OH)2 nanoarray, and DF is the SEM image of the Cu(OH)2 / Cu2S nanoarray.

[0021] Figure 2 Transmission electron microscopy (HRTEM) image of the Cu(OH)2 / Cu2S nanoarray prepared in the present invention; the lattice information of the HRTEM image indicates the successful synthesis of Cu(OH)2 / Cu2S.

[0022] Figure 3 The electrocatalytic hydrogen evolution reaction performance test of Cu(OH)2 / Cu2S prepared by the present invention; wherein A is the LSV curve; B is 10mA·cm -2 and 50mA·cm -2 The overpotential and initial overpotential of the current density; C is the Tafel slope; D is the double layer capacitance (Cdl) of the sample.

[0023] Figure 4 These are the stability test results of Cu(OH)2 / Cu2S nanoarrays. DETAILED DESCRIPTION

[0024] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0025] As mentioned above, the existing methods for preparing copper-containing nanomaterials have problems such as unstable prepared materials, easy detachment from electrodes, high production costs and complex processes, which restrict the application of copper-containing nanomaterials in the field of electrochemical materials and devices.

[0026] Studies have found that Cu(OH)2 nanoarrays grown on a copper foam substrate can be used as electrode materials in supercapacitors; however, Cu(OH)2 nanoarrays are easily oxidized to CuO during use. Cu2S is a good p-type semiconductor material, and its good nanostructure properties show great application potential. Its good photoelectric properties are widely used in solar cells. However, there are few reports on the preparation of Cu(OH)2 / Cu2S nanoarrays and their application in electrocatalytic hydrogen evolution.

[0027] In view of this, the present invention proposes for the first time a method for preparing a Cu(OH)2 / Cu2S nanoarray. The present invention first grows a Cu(OH)2 nanoarray precursor in situ on a foam copper substrate; then the Cu(OH)2 nanoarray precursor is heated to 300°C in an argon atmosphere for heat treatment to prepare a Cu(OH)2 nanoarray with relatively stable performance, which can prevent Cu(OH)2 from being oxidized to become a CuO nanoarray; then the Cu(OH)2 nanoarray is placed in a Na2S aqueous solution for sulfurization treatment to finally prepare a Cu(OH)2 / Cu2S nanoarray.

[0028] The Cu(OH)2 / Cu2S nanoarray prepared by the present invention has a flocculent structure in addition to a mesh structure, which provides a large specific surface area and active sites, and is beneficial to the electrocatalytic hydrogen evolution (HER) reaction; and the Cu(OH)2 / Cu2S prepared by the present invention has been subjected to multiple tests, and the hydrogen production performance remains unchanged, and there is no phenomenon of Cu(OH)2 / Cu2S falling off from the electrode during the test process.

[0029] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below in conjunction with specific examples. If the specific experimental conditions are not specified in the examples, they are usually in accordance with conventional conditions or the conditions recommended by the reagent company; the reagents, consumables, etc. used in the following examples, unless otherwise specified, can be obtained through commercial channels.

[0030] Example 1: Preparation of Cu(OH)2 / Cu2S nanoarrays

[0031] (1) Prepare the copper foam substrate:

[0032] The foam copper (CF) was cut into a size of 1 cm × 4 cm and placed in HCl (solution of 1 M), acetone and ethanol in turn for surface cleaning and activation treatment for 15 minutes each;

[0033] (2) Preparation of Cu(OH)2 nanoarray precursor:

[0034] The cleaned foam copper substrate was placed in a mixed aqueous solution (5 ml) containing NaOH (0.5 g) and (NH4)2S2O8 (0.1425 g) and reacted at room temperature for 0.5 h to obtain a Cu(OH)2 nanoarray precursor;

[0035] (3) Heat treatment:

[0036] The Cu(OH)2 nanoarray precursor prepared in step (2) was placed in a heat treatment furnace and subjected to heat treatment in an argon atmosphere at a heating rate of 5°C / min, and the temperature was raised to 300°C and maintained for 6 hours to obtain a dry Cu(OH)2 nanoarray;

[0037] (4) Sulfurization treatment:

[0038] The dried Cu(OH)2 nanoarray was placed in a 0.1M Na2S aqueous solution (20 ml) and subjected to hydrothermal reaction at 90°C for 3 hours to prepare a Cu(OH)2 / Cu2S nanoarray.

[0039] The structure of the Cu(OH)2 / Cu2S nanoarray prepared in this example was characterized by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM).

[0040] The SEM scanning results are as follows Figure 1 As shown, Figure 1 AC shows the SEM images of the Cu(OH)2 nanoarray (Cu(OH)2 / CF) prepared in step (3) of this example at different magnifications. Many neatly arranged smooth nanorods appear on the surface of Cu(OH)2.

[0041] Figure 1 DF in the figure are SEM images of Cu(OH)2 / Cu2S nanoarrays at different magnifications. The surface of Cu(OH)2 / Cu2S becomes loose and rough, and a network structure appears.

[0042] HRTEM images such as Figure 2 As shown, the results show that the Cu(OH)2 / Cu2S nanoarrays are alternately stacked into a network structure, and there are some flocculent structures on the surface ( Figure 2 A, B); Cu(OH)2 / Cu2S arrays have clear edges and excellent crystallinity ( Figure 2 C), where the lattice spacing between 0.250 nm and 0.253 nm corresponds to the crystal planes of Cu(OH)2(111) (represented by the blue rectangles) and Cu2S(402) (represented by the orange rectangles).

[0043] It can be concluded that the present invention successfully prepared the Cu(OH)2 / Cu2S nanoarray.

[0044] Experimental Example 1: Electrocatalytic Hydrogen Evolution Reaction Performance Testing of Cu(OH)2 / Cu2S Nanoarrays

[0045] The Cu(OH)2 / Cu2S nanoarray prepared in Example 1 was subjected to hydrogen evolution reaction (HER) performance analysis using an electrochemical workstation, and electrochemical techniques such as cyclic voltammetry and electrochemical impedance spectroscopy were used to study the electrochemical properties of the hydrogen evolution reaction, including reaction rate, electrocatalytic activity, and charge transfer process. By analyzing the electrochemical curves and impedance spectroscopy results, the performance of the catalyst or electrode material in HER can be evaluated.

[0046] Copper foam (CF) and the Cu(OH)2 nanoarray ((Cu(OH)2 / CF)) prepared in step (3) of Example 1 were used as controls.

[0047] The results are as follows Figure 3 As shown. Figure 3 The LSV polarization curve of A shows that Cu(OH)2 / Cu2S has a -1 The lower overpotential is the lowest. At the same current density, the more positive the hydrogen evolution potential is, the better the hydrogen evolution activity of the catalytic electrode is; Figure 3 As shown in B, both at the initial overpotential and at 10 mA cm -2 , 50mA cm -2 Under the overpotential of 2.5 Å, Cu(OH)2 / Cu2S has the lowest overpotential compared with the foam copper (CF) and Cu(OH)2 / CF samples, which proves that Cu(OH)2 / Cu2S has the best hydrogen evolution activity. Figure 3 C shows that compared with the copper foam (CF) and Cu(OH)2 / CF samples, the Tafel slope of Cu(OH)2 / Cu2S is the lowest, which is 64mV dec. -1 , which indicates that the Volmer reaction of Cu(OH)2 / Cu2S has higher hydrogen production efficiency and higher hydrogen production rate, proving that Cu(OH)2 / Cu2S has fast hydrogen evolution reaction kinetics. Figure 3 D shows the double-layer capacitance Cdl of the samples calculated from CV curves at different scan rates. Compared with foam copper (CF) and Cu(OH)2 / CF samples, Cu(OH)2 / Cu2S has the highest double-layer capacitance value.

[0048] In summary, compared with copper foam (CF) and Cu(OH)2 / CF samples, Cu(OH)2 / Cu2S has the best HER performance.

[0049] Experimental Example 2: Quality Stability Test of Cu(OH)2 / Cu2S Nanoarray

[0050] The quality stability of the Cu(OH)2 / Cu2S nanoarray prepared in Example 1 was investigated by cyclic voltammetry and chronoamperometry. Figure 4shown.

[0051] The results show that after 1200 cyclic voltammetry tests, the overpotential of Cu(OH)2 / Cu2S is only 5mv (10mA·cm -2 ). The stability of Cu(OH)2 / Cu2S was tested by chronoamperometry under 1.2V constant voltage and 1M KOH electrolyte. During the 16h IT test, the current hardly changed, proving the stability of the Cu(OH)2 / Cu2S sample prepared by the present invention.

[0052] This proves that the hydrogen production performance of Cu(OH)2 / Cu2S remains basically unchanged after multiple tests, and there is no phenomenon of Cu(OH)2 / Cu2S falling off from the electrode during the test.

[0053] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a Cu(OH)2 / Cu2S nanoarray, characterized in that: The following steps are involved: (1) using the cleaned and activated copper foam as a substrate, placing the substrate in an aqueous solution containing NaOH and ammonium persulfate for immersion reaction to prepare a Cu(OH)2 nanoarray precursor; (2) heat treating the Cu(OH)2 nanoarray precursor under the protection of an inert gas to obtain a Cu(OH)2 nanoarray; (3) The Cu(OH)2 nanoarray is placed in a Na2S aqueous solution for hydrothermal reaction to prepare a Cu(OH)2 / Cu2S nanoarray.

2. The preparation method according to claim 1, characterized in that: In step (1), the method for cleaning and activating the copper foam is as follows: placing the copper foam in HCl, acetone and ethanol in sequence for surface cleaning and activation for 10-20 minutes each.

3. The preparation method according to claim 1, characterized in that: In step (1), the aqueous solution contains NaOH (0.05-0.15) g / ml and ammonium persulfate (0.02-0.03) g / ml; and the soaking reaction time is 0.5h-1h.

4. The preparation method according to claim 1, characterized in that: In step (2), the inert gas is argon.

5. The preparation method according to claim 1, characterized in that: In step (2), the heat treatment temperature is 280°C-320°C, and the heat treatment time is 4h-8h.

6. The preparation method according to claim 1, characterized in that: In step (3), the temperature of the hydrothermal reaction is 85°C-95°C, and the time of the hydrothermal reaction is 2h-4h.

7. A Cu(OH)2 / Cu2S nanoarray prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the Cu(OH)2 / Cu2S nanoarray according to claim 7 in electrocatalytic hydrogen evolution.

Images