CN103952719B - Catalyst used for preparation of hydrogen through water electrolysis, and preparation method thereof - Google Patents

Abstract

The invention provides a catalyst for electrolysis of water to produce hydrogen. The catalyst is amorphous Ni-B, and the atomic ratio of nickel to boron is 2.7; The diameter range is 40-120nm, and the inside of the particle is a flower-like structure with a large specific surface, which is beneficial to the catalytic reaction of water decomposition and hydrogen evolution; the suitable solution pH range of the catalyst is 0-14. The present invention also provides a method for preparing the catalyst, comprising the following steps: using an electroless plating method to load amorphous Ni-B on the surface of a carrier, and the atomic ratio of B and Ni in the electroless plating solution is 3.0-10.0. The present invention successfully applies amorphous Ni-B to split water to catalyze hydrogen evolution reaction, and its reactivity is comparable to that of platinum. Amorphous Ni‑B has low hydrogen evolution overpotential, high catalytic efficiency, stable performance, low price, and simple preparation, making it one of the most ideal catalysts to replace noble metal Pt catalysts.

Description

Catalyst for hydrogen production by electrolysis of water and preparation method thereof

technical field

The invention belongs to the catalytic field of hydrogen production by splitting water, and in particular relates to the application of amorphous Ni-B alloy to cathode materials for electrocatalytic water splitting and hydrogen production.

Background technique

Hydrogen energy has a high combustion value, is clean and pollution-free, is rich in resources, and has a wide range of applications. The development of hydrogen energy is of great significance for alleviating energy and environmental problems in today's society. Catalytic hydrogen production from water splitting is the most important way to obtain hydrogen energy on a large scale. For the hydrogen evolution reaction, the noble metal element platinum (Pt) has excellent electrocatalytic hydrogen evolution activity in water splitting, and its hydrogen evolution overpotential is low, but it is expensive and difficult to apply on a large scale. Therefore, it is necessary to find a non-noble metal catalyst to replace Pt. hotspot. Engel Brewer's valence bond theory predicts that alloys of some transition metal elements have higher electrocatalytic activity for hydrogen evolution reaction (see L. Brewer, Bonding and structures of transition metals, Science, 1968, 161: 115-122). There have been a lot of studies on transition metal element alloys as hydrogen evolution catalysts, among which Ni-based catalysts have attracted much attention as hydrogen evolution catalysts used in alkaline solutions.

In the exploration and research of non-noble metal hydrogen evolution catalyst materials, the following two issues need to be considered: first, how to reduce the hydrogen evolution overpotential of the hydrogen evolution catalyst to reduce energy consumption and improve the hydrogen evolution efficiency of water splitting; second, how to improve the stability of the catalyst. In order to solve the above problems, we made the following analysis from the mechanism of water splitting and hydrogen evolution. Volcano graph model (VolcanoCurves) reflects the relationship between water splitting catalytic hydrogen evolution performance and catalyst surface and hydrogen adsorption energy: if the adsorption energy is too small, hydrogen cannot be adsorbed on the catalyst surface; if the adsorption energy is too large, hydrogen cannot be effectively desorbed after adsorption ( See S. Trasatti, Workfunction, electronegativity, and electrochemical behavior of metals. III. Electrolytic hydrogen evolution in acid solutions. J. Electroanal. Chem. 1972, 39: 163-184.). Only under the appropriate adsorption energy can the catalyst exhibit the best water splitting and hydrogen evolution performance. Therefore, in order to reduce the hydrogen evolution overpotential, it is necessary to adjust the electronic state structure on the surface of the catalyst, so that the hydrogen adsorption energy can reach an appropriate matching value, so as to obtain the optimal hydrogen evolution catalytic performance.

The use of amorphous alloys as catalysts began in 1981 at the Seventh International Conference on Catalytic Progress—Smith et al. reported the catalytic performance of amorphous alloys for the first time (see G.V.Smith, W.E. Brower, M.S.Matyjaszczyk, etal.Proceedings of the 7th International Congress on Catalysis , Amsterdam: Elsevier Press, 1981: 355.). Since then, amorphous materials have received increasing attention as catalysts. Compared with crystalline materials, amorphous materials have an atomic structure with long-range disorder and short-range order, which leads to the isotropy of amorphous alloys and a catalytic center with a uniform chemical environment; the surface free energy of amorphous alloys is relatively low. High, in a metastable state, the structure of this metastable state can become the active site of the reaction and improve the reactivity; the composition of the amorphous material can be continuously adjusted, so that the electronic state structure of the material surface can be effectively adjusted, and a comparative Appropriate surface adsorption energy; amorphous materials generally also have superior corrosion resistance.

For amorphous Ni-B, we can adjust the surface electronic structure of Ni-B by adjusting the composition ratio to obtain an appropriate surface adsorption energy, so as to obtain the best catalytic hydrogen evolution performance for water splitting. In addition, in the amorphous Ni-B material, B electrons will transfer to Ni, making the Ni surface in an electron-rich state, which further activates Ni to become the active center of hydrogen evolution reaction, and also prevents Ni from being oxidized. and corrosion, improving its stability. So far, there have been no reports on the use of amorphous Ni-B for electrocatalytic water splitting to produce hydrogen and obtain excellent catalytic performance.

Contents of the invention

The object of the present invention is to provide a catalyst with good catalytic performance for hydrogen production by electrolysis of water and a preparation method thereof.

In order to solve the above problems, the present invention provides a catalyst for hydrogen production by electrolysis of water, the catalyst is amorphous Ni-B, and the atomic ratio of nickel to boron is 2.7; the catalyst is a spherical granular material in appearance , the diameter range of the pellets is 40-120nm, the interior of the particles is a flower-like structure, and the specific surface is extremely large, which is beneficial to the catalytic reaction of water decomposition and hydrogen evolution; the suitable solution pH range of the catalyst is 0-14.

The present invention also provides a preparation method of the catalyst, comprising the following steps: using an electroless plating method to load amorphous Ni-B on the surface of a carrier, and the atomic ratio of B and Ni in the electroless plating solution is 3.0-10.0; The carrier is graphite, three-dimensional graphene, nickel foam or glassy carbon material, and the loading capacity is 1 mg/cm ² .

Further, the steps specifically include:

a) ultrasonically cleaning the carrier successively with water and ethanol solution;

b) subjecting the surface of the cleaned carrier to hydroxylation and hydrophilic treatment;

c) after the hydroxylation treatment of the carrier, it is placed in a silver nitrate solution and heated in an oil bath, so that the silver ions are loaded on the hydrophilic surface of the carrier;

d) After the carrier is dried naturally, put it into the chemical plating solution of nickel boride and heat it in an oil bath until the bubbles disappear, take out the carrier loaded with the catalyst, and wash it successively with ammonia water, water, alcohol and acetone until the surface of the carrier is neutral. pH = 7;

e) Drying the cleaned carrier at 80° C. in a vacuum environment.

Further, the hydroxylation hydrophilic treatment on the surface of the carrier is electrochemical oxidation hydrophilic, oxygen or water plasma etching.

Further, the reaction temperature of the chemical plating oil bath is 45-75° C., and the reaction time is 30-240 minutes.

Further, the drying temperature of Ni-B obtained by electroless plating is 80-180° C., the drying atmosphere is vacuum or inert gas, and the drying time is 5-10 hours.

Compared with the prior art, the present invention has the following technical effects:

(1) The hydrogen evolution overpotential of the catalyst is low, and the activity of splitting water and hydrogen evolution is high. We also compared the amorphous Ni-B catalyst with Pt. In different pH solutions, we found that the hydrogen evolution overpotential of amorphous Ni-B Almost as close as Pt.

(2) The composition of the amorphous Ni-B catalyst provided by the present invention can be adjusted to obtain an optimal surface electronic structure, so that the surface adsorption energy of the catalyst is at an optimum value.

(3) Compared with crystalline materials, the amorphous Ni-B catalyst provided by the present invention has higher surface free energy, and the metastable structure provides active sites for reactions, and has higher activity.

(4) The catalyst provided by the present invention is resistant to both acid and alkali, and is applicable to a wide range of solution pH values, the range of which is pH 0-14.

(5) The performance of the catalyst amorphous Ni-B provided by the invention is stable, and the electrons of B have a tendency to transfer to Ni, which makes Ni difficult to be oxidized and corroded, and has stable performance as an active site, and can be used in acid and alkaline solutions Long-term use, the activity does not attenuate.

The invention successfully applies the amorphous Ni-B to split water to catalyze the hydrogen evolution reaction, and its reactivity is comparable to that of platinum (Pt). Amorphous Ni-B has low hydrogen evolution overpotential, high catalytic efficiency, stable performance, low price, and simple preparation. It has become one of the most ideal catalysts to replace noble metal Pt catalysts.

Description of drawings

Fig. 1 a is the scanning electron microscope microscope (SEM) figure of the catalyst provided by the invention;

Fig. 1 b is the transmission electron microscope (TEM) figure of the catalyst provided by the present invention, and its selected area electron diffraction figure;

Fig. 1c is the collection of graphs of the X-ray photoelectron energy spectrum of catalyst provided by the present invention in Ni 2p district;

Fig. 1 d is the collection of graphs of the X-ray photoelectron energy spectrum of the catalyst provided by the invention in the B 1s region;

Fig. 2 is the X-ray diffraction spectrum (XRD) of the catalyst provided by the invention;

Fig. 3 a is the polarization curve of the glassy carbon electrode, blank glassy carbon electrode, nickel electrode and platinum electrode of the supported catalyst provided by the present invention in the HClO solution (pH= ₁ ) of 0.1M/L, and the scan rate is 1mV/s ;

Fig. ₃ b is the polarization curve of the glassy carbon electrode, blank glassy carbon electrode, nickel electrode and platinum electrode of the supported catalyst provided by the present invention in the HClO solution (pH=0.7) of 0.2M/L, and the scan rate is 1mV/s ;

Figure 3c shows the catalyst-loaded glassy carbon electrode, blank glassy carbon electrode, nickel electrode, and platinum electrode provided by the present invention in 0.1M/L potassium phosphate (K ₂ HPO ₄ /KH ₂ PO ₄ ) buffer solution (pH=7) The polarization curve in , the scan rate is 1mV/s;

Figure 3d is the polarization curve of the catalyst provided by the present invention loaded on a glassy carbon electrode, a blank glassy carbon electrode, a nickel electrode, and a platinum electrode in a 0.1M/L KOH solution (pH=13), with a scan rate of 1mV/s;

Fig. 4a is the catalyst provided by the present invention loaded on glassy carbon electrode, blank glassy carbon electrode, nickel electrode, the polarization curve of platinum electrode in 1M/L _HClO solution (pH=0), scan rate is 1mV/s;

Fig. ₄ b is the catalyst provided by the present invention loaded on the glassy carbon electrode in the HClO solution (pH=0) of 1M/L in the hydrogen evolution overpotential η=132mV continuous 8 hours constant potential electrolysis it curve;

Figure 5a is the polarization curve of the catalyst provided by the present invention loaded on a glassy carbon electrode, a blank glassy carbon electrode, a nickel electrode, and a platinum electrode in a 1M/L KOH solution (pH=14), and the scan rate is 1mV/s;

Figure 5b is the constant potential electrolysis i-t curve of the catalyst provided by the present invention supported on a glassy carbon electrode in 1M/L KOH solution (pH=14) at hydrogen evolution overpotential η=194mV for 8 hours.

detailed description

Embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. It should be noted that, in the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined arbitrarily with each other.

Embodiment one:

In the following, using amorphous Ni-B supported on a glassy carbon electrode as an electrocatalytic water splitting hydrogen evolution catalyst as an example, this patent will be further described in detail.

The specific preparation process of amorphous Ni-B loaded on the glassy carbon electrode is as follows:

(1) Glassy carbon electrodes (glass carbon, referred to as GC in the attached drawings) with a diameter of 5 mm were polished on the suede with 5 and 0.25 μm Al ₂ O ₃ aqueous solutions to a mirror-bright surface (all the electrodes except the glass carbon electrodes were The carrier does not need to be polished), and ultrasonically cleaned with water and ethanol solution;

(2) Put the mirror-bright glassy carbon electrode in 0.5M/L, pH=7 phosphate buffer solution, and apply a voltage of 2.0V on the glassy carbon electrode for 500s for anodic electrolysis relative to the Ag/AgCl reference electrode, so that The surface of glassy carbon is partially hydroxylated to become hydrophilic;

(3) After the hydroxylation treatment of the carrier, it is then placed in a silver nitrate solution with a mass fraction of 0.05 to 0.2%, and placed in an oil bath at 40°C for 4 hours to react, so that the silver ions are loaded on the hydrophilic carrier. surface;

(4) Take the glassy carbon electrode out of the silver nitrate solution and let it dry naturally. Then put it into the electroless plating solution of nickel boride, put it in an oil bath at 45°C to heat and react, the specific composition of the electroless plating solution is 0.05M/L nickel nitrate, 0.15M/L NaBH ₄ solution, 0.3M/L Ethylenediamine solution, 1M/L sodium hydroxide solution. The time for the glassy carbon electrode to react in the electroless plating solution is 30 minutes to 60 minutes until the bubbles disappear. At the end of the reaction, take out the glassy carbon electrode loaded with catalyst, and wash it successively with ammonia water, water, alcohol and acetone until the surface of the electrode is neutral pH=7;

(5) Dry the cleaned glassy carbon electrode in a vacuum environment at 80° C. for 5 hours.

Finally, we obtained a glassy carbon electrode loaded with amorphous Ni-B, with a loading capacity of about 1 mg/cm ² , which was then used for electrochemical experimental characterization of the hydrogen evolution performance of electrocatalytic water splitting.

As shown in Figure 1a, amorphous Ni-B is loaded on the surface of glassy carbon electrode as small spherical particles, and its average diameter is about 80nm. It can be seen from the TEM image in Figure 1b that the interior of amorphous Ni-B spheres It is petal-shaped, which is related to the release of a large amount of hydrogen gas during the preparation of Ni-B electroless plating. The petal-like internal structure increases the specific surface area of Ni-B, which is beneficial to the catalytic activity of water splitting and hydrogen evolution. From the inset of the diffraction spectrum in Figure 1b, some amorphous Debye (Debye) rings can be seen, illustrating the short-range order and long-range disordered internal structure of Ni-B. As shown in the X-ray photoelectron spectrum in Figure 1c, the two peaks at 853eV and 870eV that appear in the Ni2P spectrum in Ni-B correspond to the zero-valent state of nickel, while in the Ni 2P _3/2 spectrum they correspond to the oxidation state Ni There is no obvious peak at 856.75eV. In Figure 1d, two peaks at 187.8 and 193.3eV appear in the B 1s spectrum, corresponding to the zero-valence state of B and the oxidation state of B (B ₂ O ₃ ), respectively. This shows that B in amorphous Ni-B has a tendency to transfer electrons to Ni, so that Ni is in an electron-rich state and will not be oxidized and corroded. In addition, the atomic ratio Ni/B=2.7:1 was obtained quantitatively from the XPS spectrum.

The XRD diffraction spectrum in Figure 2 shows that there is a broad peak at θ=45°, and there are no other sharp crystal peaks, which further illustrates the amorphous structure of Ni-B.

Figure 3 shows the glassy carbon electrode loaded with amorphous Ni-B, blank glassy carbon electrode (GC), nickel electrode and platinum electrode in 0.1M HClO ₄ (pH=1), 0.2M HClO ₄ (pH=0.7), 0.1M The cathodic polarization curves in KPi (pH=7), 0.1M KOH (pH=13) solutions, we can see from the figure that in these four solutions with different pH values, the catalytic activity of nickel is almost the same as that of platinum. The hydrogen evolution overpotential of 20mA/cm ² is also almost close, which shows the superior performance of amorphous Ni-B in splitting water and hydrogen evolution. In addition, it can also be seen that the activity of the blank glassy carbon electrode and nickel electrode is relatively low, indicating that the catalytic activity of Ni-B mainly comes from itself.

Figure 4a shows the cathodic polarization curves of glassy carbon electrode loaded with amorphous Ni-B, blank glassy carbon electrode (GC), nickel electrode and platinum electrode in 1M HClO ₄ (pH=0) solution, it can be seen that the platinum electrode is in The hydrogen evolution overpotential of 20mA/cm ² is 76mV, while that of amorphous Ni-B is 132mV, which is one of the best results among all non-precious metal hydrogen evolution catalysts. In Fig. 4b is the constant potential electrolysis curve at η = 132mV, we can see that the hydrogen evolution current hardly decays with time. This shows that amorphous Ni-B can work stably in strong acidic solution.

Figure 5a shows the cathodic polarization curves of glassy carbon electrode loaded with amorphous Ni-B, blank glassy carbon electrode (GC), nickel electrode and platinum electrode respectively in 1M KOH (pH=14) solution. It can be seen from the figure that amorphous Ni-B The hydrogen evolution overpotential of B at 20mA/cm ² is 194mV, which is close to that of platinum (Pt). Figure 5b also shows the constant voltage electrolysis curve of amorphous Ni-B at an overpotential of 194mV. It can be seen that the cathode polarization current increases with time, which may be due to some B ₂ O ₃ gradually dissolves in the process of electrolysis of water, so that more Ni-B active sites are exposed, so that the current density becomes larger and larger. This phenomenon is equivalent to a catalyst activation process. The catalytic performance of amorphous Ni-B does not decay in the long-term electrolysis process in the concentrated alkali environment.

Through the above specific examples, we can see the excellent performance of amorphous Ni-B in electrocatalytic water splitting for hydrogen production, which also makes it one of the best non-precious metal hydrogen evolution catalysts to replace Pt. Amorphous Ni-B has acid and alkali resistance, low overpotential, stable performance, simple production process, and low cost, reflecting the advantages of amorphous materials as catalysts. However, the specific hydrogen evolution mechanism needs further theoretical simulation and systematic research.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (6)

1. a kind of catalyst for electric hydrogen production by water decomposition, it is characterised in that：The catalyst is the original of amorphous Ni-B, nickel and boron Son is than being 2.7；The catalyst is outward appearance granular material spherical in shape, and the diameter range of bead is 40-120nm, in particle Portion is flower-like structure, and specific surface greatly, is conducive to decomposition water liberation of hydrogen catalytic reaction；The applicable solution ph scope of the catalyst For 0～14.

2. a kind of preparation method of catalyst as claimed in claim 1, it is characterised in that comprise the steps：Using chemistry Amorphous Ni-B is carried on carrier surface by electroplating method, and B and Ni feeds intake atomic ratio for 3.0-10.0 in chemical plating fluid；The carrier is Graphite, three-dimensional grapheme, nickel foam or glass material with carbon element, load capacity is 1mg/cm²。

3. method as claimed in claim 2, it is characterised in that the step is specifically included：

A) the carrier priority water and ethanol solution are cleaned by ultrasonic clean；

B) carrier surface for cleaning up is carried out into hydroxylating hydrophilic treated；

C) after the carrier hydroxylating is processed, it is placed on oil bath heating in silver nitrate solution so that silver ion is carried on carrier parent The surface of water；

D) oil bath heating in the chemical plating fluid of nickel borides is put into after is dried naturally carrier, till bubble collapse, will be loaded The carrier of catalyst takes out, and priority ammoniacal liquor, water, and alcohol and acetone are cleaned, until carrier surface is in neutral pH=7；

E) by cleaned carrier be placed in vacuum environment it is lower 80 DEG C at be dried.

4. method as claimed in claim 3, it is characterised in that：The hydroxylating hydrophilic treated of the carrier surface is electrochemistry oxygen Change the plasma etching of hydrophilic, oxygen or water.

5. method as claimed in claim 4, it is characterised in that：The reaction temperature of chemical plating oil bath is 45-75 DEG C, the reaction time For 30-240 minutes.

6. method as claimed in claim 5, it is characterised in that：The Ni-B baking temperatures that chemical plating is obtained are 80-180 DEG C, are done Pathogenic dryness atmosphere is vacuum or inert gas, and drying time is 5-10 hour.