CN105177621B - Molybdenum-oxygen cluster modified hollow microspherical nickel disulfide catalyst and application thereof - Google Patents

Abstract

The invention relates to a molybdenum-oxygen cluster-modified nickel trisulfide micron hollow sphere catalyst and its application in electrocatalytic water splitting to produce hydrogen and oxygen, belonging to the technical field of electrocatalytic water splitting. The invention uses surface active agent, sulfur source, molybdenum source and metal nickel substrate as raw materials, and can obtain target material through one-step hydrothermal reaction. The preparation method of the invention is simple and controllable, the raw materials are cheap, the reproducibility of sample properties is good, the synthesis process is short in time consumption, the requirement for equipment is not high, and it is suitable for large-scale production. It is especially important that this material can simultaneously electrolyze water to produce hydrogen and oxygen in an alkaline electrolyzer (i.e. total water splitting). When the voltage is 1.45V, the current density can reach 10mA/cm ² , which is higher than that of noble metal platinum and oxidation. The activity of ruthenium for total water splitting is even better, and it is one of the best double-sided catalysts at present. It can greatly improve the energy conversion efficiency of converting electrical energy into chemical energy, and meets the national requirements for energy conservation and emission reduction.

Description

A molybdenum-oxygen cluster-modified trinickel disulfide micron hollow sphere catalyst and its application

technical field

The invention belongs to the technical field of electrocatalytic cracking of water, and in particular relates to a molybdenum-oxygen cluster-modified nickel disulfide micron hollow sphere catalyst and its application in electrocatalytic cracking of water for hydrogen and oxygen production.

Background technique

With the development of society and economy, people rely too much on fossil fuel energy, aggravating environmental pollution and global warming, and fossil fuels are facing depletion, so it is imminent to find an alternative green energy, and hydrogen energy has become the best choice. Electrocatalytic water splitting can convert non-storable electrical energy converted from solar energy, wind energy, and water energy into hydrogen energy. Hydrogen as a carrier can be used for energy storage or directly as an important chemical raw material. However, in the actual process of electrolyzing water, it is necessary to overcome a large overpotential, resulting in a significant drop in energy utilization, and active catalysts can effectively reduce the overpotential of electrolyzed water, thereby improving the utilization of electric energy. At present, noble metals such as platinum and palladium, and iridium and rhodium-based oxides are the most effective catalysts for electrocatalytic water splitting to produce hydrogen and oxygen, respectively, but their shortcomings of high price and extremely low reserves have seriously affected the wide application of such materials. , therefore, the development of highly active, earth-abundant non-noble metal catalysts has attracted widespread attention.

In recent years, there have been more highly active non-noble metal electrochemical water splitting catalysts, for example, efficient water splitting hydrogen production catalyst molybdenum disulfide (J.Am.Chem.Soc. 2005 127 volume 5308 pages); and water splitting Oxygen generation catalyst cobalt phosphide (Science 2008, volume 32, page 1072). Although the vast majority of electrocatalysts exhibit excellent catalytic properties under strong acid or strong alkali conditions, they cannot be used in the same electrolyzer because the optimal working conditions of their hydrogen-generating end and oxygen-generating end cannot be completely matched. Therefore, the synthesis of bifacial electrocatalysts capable of producing both hydrogen and oxygen under the same working conditions remains a great challenge.

Contents of the invention

Aiming at improving the energy utilization efficiency of converting electrical energy into chemical energy, the invention proposes a molybdenum-oxygen cluster-modified nickel disulfide micron hollow sphere catalyst and its application in electrocatalytic cracking of water for hydrogen and oxygen production.

A molybdenum-oxygen cluster-modified nickel disulfide micron hollow sphere catalyst according to the present invention is characterized in that a surfactant, a sulfur source and a molybdenum source are dissolved in water, the resulting solution is loaded into a reactor, and then added The metal nickel substrate is prepared after heating and reacting for 12h to 24h.

The surfactant is a water-soluble tri-block copolymer, including but not limited to P123, F127, etc. and mixtures thereof.

The sulfur source includes but not limited to thiourea, thioacetamide and its derivatives or mixtures thereof.

The molybdenum source is a water-soluble molybdenum salt, including but not limited to ammonium molybdate, sodium molybdate, ammonium tetrathiomolybdate and mixtures thereof.

The metallic nickel substrate includes but not limited to metallic nickel materials such as nickel foam, nickel mesh and nickel foil.

The molar ratio of sulfur to molybdenum in the sulfur source and molybdenum source is 2.4-14.4:1; the molar ratio of sulfur to surfactant is 17.4-34.9:1, and the heating temperature is 160-220°C.

The prepared molybdenum-oxygen cluster-modified trinickel disulfide micron hollow sphere catalyst can be used not only as a negative electrode for electrocatalytically splitting water to produce hydrogen, but also as a positive electrode for electrocatalytically splitting water to produce oxygen, and is a dual-functional water splitting catalyst.

Beneficial effect

Compared with the prior art, the present invention has the following innovations:

1. The synthesis raw materials are cheap, the synthesis temperature is low, the synthesis steps are simple, the controllability is high, and the sample properties are reproducible.

2. The obtained molybdenum-oxygen cluster-modified trinickel disulfide is distributed on the metal nickel substrate in the form of micron hollow spheres (500nm-1μm in diameter) constructed of ultra-thin (thickness about 1.3nm) nanosheets. The micron hollow spheres constructed by ultrathin nanosheets on the substrate greatly improve the electrochemical catalytic area and mass transfer efficiency of the obtained material.

3. The obtained material is a new type of electrocatalytic water splitting catalyst, which exhibits excellent catalytic activity and stability in the full pH range (0-14), and electrolyzes water to produce hydrogen under alkaline conditions (pH 14). When the overpotential of oxygen is 106mV and 136mV respectively, the current density can reach 10mA/cm ² , and the performance is stable. When the voltage is 1.45V, the current density can reach 10mA/cm ² , which is one of the best double-sided electrocatalytic water splitting catalysts at present.

4. The obtained material does not require a binder, and can be directly used as a working electrode for water splitting, which improves the electron transfer rate of the electrocatalyst, reduces the loss of electrical energy, and improves the energy utilization efficiency of converting electrical energy into chemical energy.

Description of drawings

Fig. 1: the XRD spectrogram of the trinickel disulfide catalyst modified by the molybdenum oxygen cluster obtained in embodiment 1;

Fig. 2: the Raman spectrogram of the trinickel disulfide catalyst modified by the molybdenum oxygen cluster obtained in embodiment 1;

Fig. 3: the SEM picture of the trinickel disulfide catalyst modified by the molybdenum oxygen cluster obtained in embodiment 1;

Fig. 4: The trinickel disulfide catalyst of molybdenum oxygen cluster modification obtained in embodiment 1 is in acidic (pH is 0, Fig. A), neutral (pH is 7, Fig. B), alkaline (pH is 14, Fig. C ) The hydrogen production performance of the electrocatalytic cracking water (deionized water) in the electrolyte, that is, the current density versus the potential change curve of the reversible hydrogen electrode;

Fig. 5: The trinickel disulfide catalyst that the molybdenum oxygen cluster modification obtained in embodiment 1 is acidic (pH is 0, Fig. A), neutral (pH is 7, Fig. B), alkaline (pH is 14, Fig. C ) The catalytic stability curve obtained in the electrolyte, that is, the current density curve with time under constant voltage;

Figure 6: Polarization curve (figure A) of the electrocatalytic splitting of water (deionized water) produced by the nickel disulfide catalyst modified by the molybdenum oxygen cluster obtained in Example 1 in alkaline (pH is 14) electrolyte and catalytic stability curve (Figure B);

Figure 7: Polarization curve (Figure A) and stability curve (Figure B) of the molybdenum-oxygen cluster-modified nickel disulfide catalyst obtained in Example 1 as a double-sided electrocatalyst for electrolysis of water in an alkaline electrolyzer.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and embodiments, but the protection scope of the present invention is not limited to the following embodiments.

Example 1

Dissolve 10mg of ammonium molybdate, 45mg of thioacetamide and 0.15g of P123 in 30mL of deionized water, add it to a 60mL reaction kettle, then put in foamed nickel (thickness 1.5mm, bulk density 0.23mg/cm ³ ), 200°C After reacting for 24 hours, the molybdenum-oxygen cluster-modified trinickel disulfide micron hollow sphere catalyst can be obtained.

Some structural characterizations of the catalysts prepared by the above method were carried out. Fig. 1 is the XRD spectrogram of the obtained catalyst, and the peak position in the spectrogram is consistent with PDF#44-1418, indicating that the catalyst is hexagonal Ni ₃ S ₂ ; Fig. 2 is the Raman spectrogram of the obtained catalyst, which can be seen The obtained catalyst is MoO _x modified Ni ₃ S ₂ ; Figure 3 is the SEM photo of the obtained catalyst, and it can be seen that the catalyst is a micron hollow sphere composed of ultrathin nanosheets.

The catalyst prepared by the above method is tested in a standard three-electrode electrolytic cell to electrocatalytically crack water to produce hydrogen and oxygen; The calomel electrode and the counter electrode are carbon rods. It should be noted that all the potentials obtained with the saturated calomel electrode as the reference electrode in the electrocatalytic test are converted into reversible hydrogen electrode potentials in the property diagram. The total water splitting in the alkaline electrolyzer was tested under two-electrode conditions, and the synthesized molybdenum-oxygen cluster-modified trinickel disulfide catalyst was used as the hydrogen-producing end and the oxygen-producing end of the electrolyzed water, respectively.

Figure 4 shows that the catalyst is acidic (pH is 0, 0.5MH ₂ SO ₄ ), neutral (pH is 7, 1M K ₂ HPO ₄ and 1M KH ₂ PO ₄ are mixed in corresponding proportions), alkaline (pH is 14, 1M KOH) electrocatalytic cracking water hydrogen production and oxygen production property diagram obtained in the electrolyte, it can be seen that:

Electrocatalytic cracking of water to produce hydrogen;

Under the condition of pH 0, when the overpotential is 123mV, the current density of the catalyst reaches 10mA/cm ² ;

Under the condition of pH 7, when the overpotential is 192mV, the current density of the catalyst reaches 10mA/cm ² ;

Under the condition of pH 14, when the overpotential is 106mV, the current density of the catalyst reaches 10mA/cm ² ;

The above results indicate that the catalyst has excellent electrocatalytic hydrogen production activity in the whole pH range.

Electrocatalytic water splitting to produce oxygen;

Under the condition of pH 14, when the overpotential is 136mV, the current density of the catalyst reaches 10mA/cm ² .

Figure 5 is a diagram of the catalytic stability properties of electrolyzed water hydrogen production and alkaline oxygen production obtained by the catalyst in acidic (pH 0), neutral (pH 7) and alkaline (pH 14) electrolytes, the applied overpotential They are 0.12V, 0.19V, 0.11V, and 0.15V respectively; it can be seen that under the condition of high current density (10-20mA/cm ² ), the catalytic performance of the material remains stable after a long time (200 hours) of operation.

Fig. 6 is the property and stability performance of the electrocatalytic water splitting of the total water splitting in the alkaline (pH is 14, 1M KOH) electrolyzer of this catalyst, as can be seen:

Under the condition of pH 14, after forming an electrolytic cell, when the applied voltage is 1.45V, the current density of the catalyst reaches 10mA/cm ² , and its catalytic performance does not change after a long time (100 hours) of work.

Example 2

Same as Example 1, except that the amount of ammonium molybdate was changed to 60 mg. The electrocatalytic properties of the resulting catalyst:

Electrocatalytic cracking of water to produce hydrogen;

Under the condition of pH 0, when the overpotential is 153mV, the current density of the catalyst reaches 10mA/cm ² ;

Under the condition of pH 7, when the overpotential is 182mV, the current density of the catalyst reaches 10mA/cm ² ;

Under the condition of pH 14, when the overpotential is 126mV, the current density of the catalyst reaches 10mA/cm ² ;

Electrocatalytic water splitting to produce oxygen;

Under the condition of pH 14, when the overpotential is 143mV, the current density of the catalyst reaches 10mA/cm ² ;

After forming the electrolytic cell;

Under the condition of pH 14, when the applied voltage is 1.51V, the current density of the catalyst reaches 10mA/cm ² .

Example 3

Same as Example 1 except that the reaction temperature was changed to 160°C. Electrocatalytic properties of the obtained samples:

Electrocatalytic cracking of water to produce hydrogen;

Under the condition of pH 0, when the overpotential is 158mV, the current density of the catalyst reaches 10mA/cm ² ;

Under the condition of pH 7, when the overpotential is 190mV, the current density of the catalyst reaches 10mA/cm ² ;

Under the condition of pH 14, when the overpotential is 140mV, the current density of the catalyst reaches 10mA/cm ² ;

Electrocatalytic water splitting to produce oxygen;

Under the condition of pH 14, when the overpotential is 155mV, the current density of the catalyst reaches 10mA/cm ² ;

After forming the electrolytic cell:

Under the condition of pH 14, when the applied voltage is 1.53V, the current density of the catalyst reaches 10mA/cm ² .

Example 4

Same as Example 1, except that the amount of surfactant is changed to 0.3g. Electrocatalytic properties of the obtained samples:

Electrocatalytic cracking of water to produce hydrogen;

Under the condition of pH 0, when the overpotential is 160mV, the current density of the catalyst reaches 10mA/cm ² ;

Under the condition of pH 7, when the overpotential is 188mV, the current density of the catalyst reaches 10mA/cm ² ;

Under the condition of pH 14, when the overpotential is 156mV, the current density of the catalyst reaches 10mA/cm ² ;

Electrocatalytic water splitting to produce oxygen;

Under the condition of pH 14, when the overpotential is 162mV, the current density of the catalyst reaches 10mA/cm ² ;

After forming the electrolytic cell:

Under the condition of pH 14, when the applied voltage is 1.55V, the current density of the catalyst reaches 10mA/cm ² .

Example 5

Same as Example 1, except that the reaction time was reduced to 12h. Electrocatalytic properties of the obtained samples:

Electrocatalytic cracking of water to produce hydrogen;

Under the condition of pH 0, when the overpotential is 133mV, the current density of the catalyst reaches 10mA/cm ² ;

Under the condition of pH 7, when the overpotential is 192mV, the current density of the catalyst reaches 10mA/cm ² ;

Under the condition of pH 14, when the overpotential is 121mV, the current density of the catalyst reaches 10mA/cm ² ;

Electrocatalytic water splitting to produce oxygen;

Under the condition of pH 14, when the overpotential is 138mV, the current density of the catalyst reaches 10mA/cm ² ;

After forming the electrolytic cell:

Under the condition of pH 14, when the applied voltage is 1.5V, the current density of the catalyst reaches 10mA/cm ² .

Example 6

Same as embodiment 1, just change ammonium molybdate into sodium molybdate. Electrocatalytic properties of the obtained samples:

Electrocatalytic cracking of water to produce hydrogen;

Under the condition of pH 0, when the overpotential is 143mV, the current density of the catalyst reaches 10mA/cm ² ;

Under the condition of pH 7, when the overpotential is 191mV, the current density of the catalyst reaches 10mA/cm ² ;

Under the condition of pH 14, when the overpotential is 137mV, the current density of the catalyst reaches 10mA/cm ² ;

Electrocatalytic water splitting to produce oxygen;

Under the condition of pH 14, when the overpotential is 153mV, the current density of the catalyst reaches 10mA/cm ² ;

After forming the electrolytic cell;

Under the condition of pH 14, when the applied voltage is 1.52V, the current density of the catalyst reaches 10mA/cm ² .

Example 7

Same as Example 1, just change thioacetamide to thiourea. Electrocatalytic properties of the obtained samples:

Electrocatalytic cracking of water to produce hydrogen;

Under the condition of pH 0, when the overpotential is 131mV, the current density of the catalyst reaches 10mA/cm ² ;

Under the condition of pH 7, when the overpotential is 194mV, the current density of the catalyst reaches 10mA/cm ² ;

Under the condition of pH 14, when the overpotential is 117mV, the current density of the catalyst reaches 10mA/cm ² ;

Electrocatalytic water splitting to produce oxygen;

Under the condition of pH 14, when the overpotential is 128mV, the current density of the catalyst reaches 10mA/cm ² ;

After forming the electrolytic cell;

Under the condition of pH 14, when the applied voltage is 1.48V, the current density of the catalyst reaches 10mA/cm ² .

Example 8

Same as Example 1, only nickel foam is changed to nickel foil. Electrocatalytic properties of the obtained samples:

Electrocatalytic cracking of water to produce hydrogen;

Under the condition of pH 0, when the overpotential is 156mV, the current density of the catalyst reaches 10mA/cm ² ;

Under the condition of pH 7, when the overpotential is 206mV, the current density of the catalyst reaches 10mA/cm ² ;

Under the condition of pH 14, when the overpotential is 146mV, the current density of the catalyst reaches 10mA/cm ² ;

Electrocatalytic water splitting to produce oxygen;

Under the condition of pH 14, when the overpotential is 183mV, the current density of the catalyst reaches 10mA/cm ² ;

After forming the electrolytic cell;

Under the condition of pH 14, when the applied voltage is 1.57V, the current density of the catalyst reaches 10mA/cm ² .

Example 9

Same as Example 1, only change P123 to F127. Electrocatalytic properties of the obtained samples:

Electrocatalytic cracking of water to produce hydrogen;

Under the condition of pH 0, when the overpotential is 139mV, the current density of the catalyst reaches 10mA/cm ² ;

Under the condition of pH 7, when the overpotential is 198mV, the current density of the catalyst reaches 10mA/cm ² ;

Under the condition of pH 14, when the overpotential is 127mV, the current density of the catalyst reaches 10mA/cm ² ;

Electrocatalytic water splitting to produce oxygen;

Under the condition of pH 14, when the overpotential is 158mV, the current density of the catalyst reaches 10mA/cm ² ;

After forming the electrolytic cell;

Under the condition of pH 14, when the applied voltage is 1.54V, the current density of the catalyst reaches 10mA/cm ² .

The above-described implementation is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, any changes that can be easily imagined by those skilled in the art within the spirit and principles of the present invention, replacement and improvements should be covered within the protection scope of the present invention.

Claims (5)

1. the nickel micrometre hollow sphere catalyst of curing three that a kind of molybdenum oxygen cluster is modified, it is characterised in that：It is by surfactant, sulphur Source and molybdenum source are soluble in water, and resulting solution is loaded into reactor, are subsequently adding metal nickel substrate, make after heating response 12h~24h It is standby to obtain；Sulphur source is 2.4~14.4 with the mol ratio of molybdenum element with element sulphur in molybdenum source：1, element sulphur rubs with surfactant You are than being 17.4~34.9：1, heating-up temperature is 160~220 DEG C；Wherein, surfactant is water-soluble triblock copolymer Thing, sulphur source is thiocarbamide, thioacetamide and its derivative or its mixture, and molybdenum source is ammonium molybdate, sodium molybdate, four thio ammonium molybdate Or its mixture.

2. the nickel micrometre hollow sphere catalyst of curing three that a kind of molybdenum oxygen cluster as claimed in claim 1 is modified, it is characterised in that： Surfactant is P123 or F127.

3. the nickel micrometre hollow sphere catalyst of curing three that a kind of molybdenum oxygen cluster as claimed in claim 1 is modified, it is characterised in that： Metal nickel substrate is nickel foam, nickel screen or nickel foil.

4. a kind of nickel micrometre hollow sphere catalyst of curing three of the molybdenum oxygen cluster modification described in claims 1 to 3 any one exists Application in terms of electrolysis water.

5. a kind of nickel micrometre hollow sphere catalyst of curing three of molybdenum oxygen cluster modification as claimed in claim 4 is in terms of electrolysis water Application, it is characterised in that：The negative pole or the positive pole as electro-catalysis cracking aquatic products oxygen of aquatic products hydrogen are cracked as electro-catalysis.