CN112981443A

CN112981443A - Foam nickel with nano silver film deposited on surface, preparation method and application thereof

Info

Publication number: CN112981443A
Application number: CN202110197810.0A
Authority: CN
Inventors: 赵旭; 王湘越; 赵纯
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2021-02-22
Filing date: 2021-02-22
Publication date: 2021-06-18
Anticipated expiration: 2041-02-22
Also published as: CN112981443B

Abstract

A foamed nickel with a surface deposited with a nano silver film, a preparation method and application thereof in hydrogen production by sulfur-iodine (S-I) cycle Bunsen reaction (Bunsen) product electrolysis, belonging to the technical field of nano synthesis. The invention uses high temperature adhesive tape to fix the foam nickel on the evaporation rack of metal thermal evaporation coating equipment, cuts a proper amount of silver wire to wind the silver wire on the tungsten wire, and fixes the silver wire in the heating circuit; vacuumizing a reaction chamber of the metal thermal evaporation coating equipment, opening a heating circuit switch, and depositing a nano silver film on the surface of one side of the foamed nickel; and after the deposition is finished and the temperature is reduced to the room temperature, turning over the foamed nickel, and depositing the nano silver film on the surface of the other side of the foamed nickel according to the previous operation steps, wherein the thickness of the nano silver film is 30-200 nm. The invention uses micro silver by using a thermal evaporation method, and deposits a uniform nano silver film on the foam nickel, thereby not only protecting the foam nickel from being corroded and being capable of being repeatedly utilized, but also improving the conductivity and the catalytic performance.

Description

Foam nickel with nano silver film deposited on surface, preparation method and application thereof

Technical Field

The invention belongs to the technical field of nano synthesis, and particularly relates to foamed nickel with a nano silver film deposited on the surface, a preparation method and application thereof in hydrogen production by sulfur-iodine (S-I) cycle Bunsen reaction (Bunsen) product electrolysis.

Background

In the beginning of the last century, with the continuous development of the world industry, climate change and environmental pollution caused by the use of fossil fuels have forced people to consider clean energy and renewable resources. Hydrogen is used as an alternative energy source and has the characteristics of cleanness and reproducibility, so that large-scale hydrogen production becomes an important target of scientific research work, and until the 80S, an S-I thermodynamic cycle emerges, and the reaction system is considered as one of important ways for large-scale hydrogen production, so researchers have conducted a great deal of research on the reaction process, and finally, the reaction system is definitely composed of three parts: bunsen reaction, sulfuric acid decomposition reaction and hydroiodic acid decomposition reaction. Among them, the decomposition of sulfuric acid and hydroiodic acid requires a large amount of heat, and this research falls into a bottleneck and cannot be widely popularized and applied. With the coming of the 21 st century, the field of electrocatalysis is gradually matured, S-I circulation reflects the eye of researchers again, and the work of hydrogen production by hydroiodic acid electrolysis by adopting a Pt electrode is rapidly developed in the decade. The related studies found that hydriodic acid is significantly lower than water compared to the electrolysis voltage, which also made it the focus of the electrocatalytic field again. However, Pt is a precious metal material, and has significant problems of low yield and high cost, so that it has not been industrially produced. The search for a material which has the advantages of acid resistance and strong electrocatalysis capability of Pt and has relatively low cost becomes a new research direction.

The foamed nickel as the substrate has the advantages of porous structure, high specific surface area, excellent conductivity and the like, but is not resistant to acid solution corrosion. The surface is plated with the nano silver film, so that the electron transmission is effectively improved, the surface is not easy to corrode in an acid solution, and the effect of protecting the foamed nickel is realized.

The prior patent of using foamed nickel as a substrate as an electrocatalyst is not much, and the catalytic performance in an acid electrolyte is less, and the following inventions of the related art are briefly introduced.

1. CN112080756A discloses a method for etching a foamed nickel surface and chemically depositing micro platinum and iridium nanoparticles among layered nickel hydroxide, which can increase the decomposition rate of water due to the synergistic effect between transition metal nickel hydroxide and platinum, realize efficient hydrogen evolution in alkaline and neutral electrolytes, and have excellent stability. Can be applied to the electrolytic hydrogen production of a metal/seawater system.

2. CN111912890A discloses a nano silver/carbon quantum dot deposition modified foam nickel electrode. By utilizing the high electrocatalysis and good biocompatibility of the nano-silver and the special synergistic effect of the carbon quantum dots, namely high specific surface area and multiple active sites, the obtained composite material is more sensitive and wider in detection range than a single material modified foam nickel electrode, and can be more stably applied to electrochemical detection.

3. CN111235600A discloses a foamed nickel catalytic electrode with a surface modified iron ion doped tungsten oxide hydrate. After hydrothermal synthesis, the tungsten oxide hydrate formed on the surface of the electrode is in a quadrangular pyramid shape, so that the point discharge effect on the surface of the electrode greatly reduces the working voltage in hydrogen production by alkaline electrolysis, and the tungsten oxide hydrate is expected to replace noble metal to be applied in hydrogen evolution reaction.

4. CN109267117A discloses a foamed nickel catalytic electrode with a surface multi-stage nano composite structure. And loading copper nanowires on the foamed nickel by adopting an electrodeposition method and compounding cobalt hydroxide nanosheets. Adjusting the concentration of a copper salt solution to be 0.05-2.5 mol/L, the concentration of acid to be 0.1-3.5 mol/L, and the molar ratio of nickel salt to cobalt salt in a metal salt solution to be 1: 10-10: 1. the total metal ion concentration is 0.005-0.5 mol/L, and the optimal condition is selected. The electrode has the advantages of high specific surface area, high capacity, high electrochemical activity and better cycling stability in an alkaline aqueous solution, and can be used in various multi-electro-catalysis fields.

Disclosure of Invention

The invention aims to provide a nickel foam with a strong acid solution corrosion resistance and a nano silver film deposited on the surface, a preparation method and application thereof in hydrogen production (S-I circulation) by electrolysis of a Bunsen reaction product. The invention uses metal thermal evaporation method to evaporate a layer of even silver film on the surface of the foam nickel.

The invention relates to a preparation method of foam nickel with a nano silver film deposited on the surface, which comprises the following steps:

(1) surface treatment of foamed nickel

Ultrasonically treating the sheared foam nickel (1 multiplied by 1cm) for 15-30 minutes by using hydrochloric acid (2-5 mol/L), distilled water and ethanol (the mass fraction is more than or equal to 99.7%), and naturally airing to obtain the foam nickel after surface treatment;

(2) preparation of foamed nickel with nano silver film deposited on surface by metal thermal evaporation

Fixing the foamed nickel subjected to surface treatment in the step (1) on an evaporation frame of metal thermal evaporation coating equipment by using a high-temperature adhesive tape, shearing a proper amount of silver wire, winding the silver wire on a tungsten wire, and fixing the tungsten wire in a heating circuit; vacuumizing the reaction chamber of the metal thermal evaporation coating equipment to 1 x 10^-3～5×10^-3Pa, opening a heating circuit switch, and depositing a nano silver film on the surface of one side of the foamed nickel; and after the deposition is finished and the temperature is reduced to the room temperature, turning over the foamed nickel, and depositing the nano silver film on the other side surface of the foamed nickel according to the previous operation steps, thereby obtaining the foamed nickel with the nano silver film deposited on the surface, wherein the thickness of the nano silver film is 30-200 nm.

The conception of the invention is as follows: foamed nickel, as a base material, is susceptible to corrosion in acidic electrolytes. The method of thermal evaporation is utilized to deposit a uniform nano silver film on the foam nickel by using trace silver, thereby not only protecting the foam nickel from being corroded and being capable of being repeatedly utilized, but also improving the conductivity and the catalytic performance.

Application prospect

The invention uses foam nickel as a substrate and utilizes a metal thermal evaporation method to obtain a foam nickel electrode with a surface deposited with a uniform nano silver film. The nano silver film foamed nickel electrode prepared by the method has high conductivity, excellent catalytic activity and better stability in strong acid electrolyte, and can be applied to a hydrogen production system by electrolysis of a Bunsen reaction product (sulfur-iodine cycle). The material of the invention is used as an anode, which has better electrocatalytic activity. Taking a nano silver film sample with the thickness of 30nm as an example, after 200 cycles of cyclic voltammetry, the surface current density of the electrode can reach 300mA/cm under the overpotential of 0.39V²And has excellent stability.

Drawings

The invention adopts FEI XL30ESEM-FEG (Holland FEI company) Field Emission Scanning Electron Microscope (FESEM) to observe the crystal morphology of a product, ESCLAB 250 (American thermal power company) X-ray photoelectron spectrometer is used for carrying out electron spectrum test on the product, the electrochemical performance test is carried out by using a CS120H electrochemical workstation (Wuhan Cornst instruments GmbH), and the properties of the morphology, the composition and the like are characterized as follows:

FIG. 1 is a linear voltammogram of the nickel foam with the surface deposited with the nano-silver thin film prepared in examples 1-4. The film thicknesses of

curves

1, 2, 3, 4 were 30nm, 50nm, 100nm, 200nm, respectively, and curve 5 was the linear voltammogram of undeposited foamed nickel.

FIG. 2 is a linear voltammogram of the nickel foams prepared in examples 1 and 6 and having a thickness of 30nm and a double-sided and single-sided deposition of nano-silver thin films, respectively. Curve 5 is the linear voltammogram of the undeposited nickel foam.

FIG. 3 is a Field Emission Scanning Electron Microscope (FESEM) photograph of undeposited nickel foam of example 5.

Fig. 4 is a Field Emission Scanning Electron Microscope (FESEM) photograph of the nickel foam with the nano-silver thin film deposited on the surface prepared in example 1.

FIG. 5 is an XPS spectrum of the foamed nickel after testing of the surface-deposited nano-silver thin film prepared in example 1. In FIG. 5, (a) is an XPS spectrum of Ni 2p, (b) is an XPS spectrum of O1s, and (c) is an XPS spectrum of Ag 3 d.

FIG. 6 is EDS energy spectrum of Ag after electrochemical testing of foamed nickel with nano-silver film deposited on the surface prepared in example 1.

FIG. 7 is an EDS energy spectrum of Ni after electrochemical testing of foamed nickel with a surface deposited nano-silver thin film prepared in example 1.

Fig. 8 is a potentiostatic diagram of the foamed nickel with the nano-silver thin film deposited on the surface prepared in example 1.

FIG. 9 is a comparison graph of theoretical hydrogen production and actual hydrogen production of nickel foam with a nano-silver film deposited on the surface prepared in example 1.

FIG. 1 is a linear voltammogram of the nickel foam with the surface deposited with the nano-silver thin film prepared in examples 1-4 (the working electrode is the nickel foam electrode with the surface deposited with the nano-silver thin film, and the counter electrode is the platinum electrode with the same area). As can be seen from the linear voltammetry curve, the foamed nickel electrode after surface modification has more excellent electrochemical performance compared with the untreated pure foamed nickel electrode. The current density is 300mA/cm²When the overpotentials required for depositing the nano-silver films with the thicknesses of 30nm, 50nm, 100nm and 200nm are respectively 0.39V, 0.44V, 0.45 and 0.48V, and the current density of an untreated pure foamed nickel electrode is only 285mA/cm under the overpotential of 0.6V²。

Fig. 2 is a linear voltammogram of the foamed nickel with the nano silver thin film deposited on both sides and one side respectively prepared in examples 1 and 6 (the working electrode is a foamed nickel electrode with the nano silver thin film deposited on the surface, and the counter electrode is a platinum electrode with the same area). Compared with a foam nickel electrode with a single-sided deposited nano silver film and a pure foam nickel electrode, the foam nickel electrode with the double-sided deposited nano silver film has better electrochemical performance. The current density is 300mA/cm²When the nickel foam with the nano silver film deposited on the double surfaces and the single surface respectively has the over-potential of 0.39V and 0.52V, the current density of the untreated pure nickel foam electrode is only 285mA/cm under the over-potential of 0.6V²。

Fig. 3 is a FESEM photograph of untreated pure nickel foam of example 5, which can be seen to be relatively smooth on the surface of the pure nickel foam.

Fig. 4 is a femsem photograph of the foamed nickel with a 30nm silver thin film deposited on the surface prepared in example 1, and comparing fig. 3, it can be seen that a uniform nano silver thin film is deposited on the surface.

FIG. 5 is an XPS energy spectrum of the foamed nickel with the surface deposited nano-silver thin film prepared in example 1 after electrochemical testing. In FIG. 5(a), diffraction peaks having binding energies of 873.8eV and 856.0eV are assigned to Ni 2p_1/2And Ni 2p_3/2And the energy difference is 17.8eV, it is proved that the existing valence state of Ni is Ni²⁺The same conclusions were drawn for the satellite peaks appearing at 879.10eV and 856.00eV, while the diffraction peak at 852.80eV, which matches that of elemental nickel, demonstrates that the surface nickel is not fully oxidized and remains partially; FIG. 5(b) is a characteristic peak of O1s, binding energy 531.40eV corresponds to a Ni-O bond; FIG. 5(c) is a characteristic peak of Ag 3d, with peak positions of 374.27eV and 368.16eV, respectively, which together demonstrate the presence of elemental Ag. In conclusion, the nano silver film deposited on the surface of the foamed nickel after the electrochemical test still exists.

Fig. 6 is an EDS spectrum of the Ag after the electrochemical performance test of the foam nickel with the nano silver film deposited on the surface prepared in example 1, and it can be seen that the nano silver film on the surface of the foam nickel still exists and is uniformly distributed after the test.

Fig. 7 is an EDS spectrum of Ni after electrochemical performance test of the nickel foam with the surface deposited with the nano-silver thin film prepared in example 1, and it can be seen that the nickel foam is relatively completely protected and is not corroded in the acidic solution after the test, and the nano-silver thin film protects the nickel foam, so that the nickel foam can be used as a catalytic electrode in the acidic solution.

FIG. 8 is a potentiostatic diagram of foamed nickel with a surface-deposited nanosilver film prepared in example 1, which is relatively stable at a current of 600 s.

FIG. 9 is a comparison graph of theoretical hydrogen production and actual hydrogen production of nickel foam with a nano-silver film deposited on the surface prepared in example 1. The working electrode is a foam nickel electrode with a nano silver film deposited on the surface at the anode, and the counter electrode is a platinum electrode with the same area at the cathode. Two electrodes are respectively placed in a closed two-chamber electrolytic cell, one side of the electrolytic solution is hydriodic acid and sulfuric acid mixed solution, and the other side of the electrolytic solution is sulfuric acid solution with a certain concentration. And connecting a hydrogen collecting device at one side of the cathode to perform electrochemical test. Since the amount of current is related to the amount of hydrogen produced, the theoretical amount of hydrogen produced can be calculated by faraday's law. It can be seen from the figure that the theoretical hydrogen yield is basically consistent with the actually measured hydrogen yield, and the Faraday efficiency of the electrocatalytic iodine separation of the surface-deposited nano silver film prepared by the method is close to 100 percent.

The Faraday efficiency calculation method comprises the following steps:

N_T＝Q/nF

η＝(N_E/N_T)*100％

wherein N is_TTo theoretical hydrogen production, N_EFor the actual hydrogen production by electrolysis, the hydrogen quantity Q collected by the device is the total charge quantity in the electrolysis process, and is obtained by integrating a constant potential i-t curve, F is a Faraday constant, n is the electron quantity obtained and lost in the electrochemical reaction, and eta is the Faraday efficiency.

Detailed Description

The present invention will be described below with reference to specific embodiments, but the present invention is not limited thereto.

Example 1

(1) Surface treatment of foamed nickel

Ultrasonically treating the sheared foam nickel (1 multiplied by 1cm) for 20 minutes by using hydrochloric acid (3mol/L), distilled water and ethanol (the mass fraction is more than or equal to 99.7 percent) respectively to obtain surface-treated foam nickel;

(2) thermal evaporation of metals

Fixing the foamed nickel subjected to surface treatment in the step (1) on an evaporation frame of DM-300B metal thermal evaporation coating equipment (Beijing Innovation vacuum technology, Inc.), shearing a proper amount of silver wires, winding the silver wires on tungsten wires, fixing the tungsten wires in a heating circuit, and then updating a crystal oscillator wafer for a film thickness meter. The reaction chamber of the metal thermal evaporation coating equipment is vacuumized to 3 multiplied by 10 by utilizing a mechanical pump and a molecular pump^-3Pa, opening a heating circuit switch, increasing circuit current until the tungsten filament is bright, reading the growth rate and the film thickness by using a film thickness meter, and adjusting the heating current again to stabilize the growth rate at

Finally, when the film thickness meter displays the required reading, the addition is closedA thermal circuit switch is used for obtaining the foamed nickel with the nano silver film deposited on the surface of one side after the temperature is reduced to the room temperature; then the foamed nickel is turned over, and the operation is continued on the other side surface of the foamed nickel, so that the foamed nickel with the surface deposited with the nano silver film is obtained, and the thickness of the nano silver film is 30 nm. The test results are shown in fig. 1, curve 1, fig. 4, fig. 5, fig. 6, fig. 7, fig. 8 and fig. 9.

Example 2

The deposition time was adjusted as in example 1 to obtain a silver nano-film with a thickness of 50 nm. The test results are shown in FIG. 1, curve 2.

Example 3

The deposition time was adjusted as in example 1 to obtain a silver nano-film having a thickness of 100 nm. The test results are shown in FIG. 1, curve 3.

Example 4

The deposition time was adjusted as in example 1 to obtain a silver nano-film having a thickness of 200 nm. The test results are shown in FIG. 1, curve 4.

Example 5

Ultrasonically treating the sheared foam nickel (1 multiplied by 1cm) for 20 minutes by using hydrochloric acid (3mol/L), distilled water and ethanol (the mass fraction is more than or equal to 99.7 percent) respectively to obtain the foam nickel; the test results are shown in FIG. 1, curve 5 and FIG. 3.

Example 6

As in example 1, the deposition of the nano-silver thin film was performed only on one side surface of the nickel foam, and the thickness of the obtained nano-silver thin film was 30 nm. The test results are shown in curve 6 of fig. 2.

Claims

1. A preparation method of foam nickel with a surface deposited with a nano silver film comprises the following steps:

(1) surface treatment of foamed nickel

Ultrasonically treating the sheared foam nickel for 15-30 minutes by using hydrochloric acid, distilled water and ethanol respectively, and naturally airing to obtain surface-treated foam nickel;

Fixing the foamed nickel subjected to surface treatment in the step (1) to metal hot evaporation plating by using a high-temperature adhesive tapeOn an evaporation frame of the film equipment, cutting a proper amount of silver wires to be wound on tungsten wires, and fixing the tungsten wires into a heating circuit; vacuumizing the reaction chamber of the metal thermal evaporation coating equipment to 1 x 10^-3～5×10^-3Pa, opening a heating circuit switch, and depositing a nano silver film on the surface of one side of the foamed nickel; and after the deposition is finished and the temperature is reduced to the room temperature, overturning the foamed nickel, and depositing the nano silver film on the other side surface of the foamed nickel according to the previous operation steps, so that the foamed nickel with the nano silver film deposited on the surface is obtained, and the thickness of the nano silver film is 30-200 nm.

2. The method for preparing the foam nickel with the nano silver film deposited on the surface as claimed in claim 1, wherein the method comprises the following steps: the concentration of the hydrochloric acid is 2-5 mol/L, and the mass fraction of the ethanol is more than or equal to 99.7%.

3. A foam nickel with a nano silver film deposited on the surface is characterized in that: is prepared by the method of claim 1 or 2.

4. The use of the nickel foam with the surface deposited with the nano-silver film as claimed in claim 3 in hydrogen production by sulfur-iodine cycle Bunsen reaction product electrolysis.