阅读说明：本技术 用于产氢的复合材料 (Composite material for hydrogen production ) 是由 郑尹玮 刘全璞 黄俊翰 于 2020-05-25 设计创作，主要内容包括：本发明公开了一种用于产氢的复合材料,包括多个壳核结构,其中各壳核结构包括含硅核心层及包覆含硅核心层表面的壳层,且壳层包括包覆含硅核心层表面的亲水层以及包覆亲水层的碱性物质。(The invention discloses a composite material for hydrogen production, which comprises a plurality of shell-core structures, wherein each shell-core structure comprises a silicon-containing core layer and a shell layer covering the surface of the silicon-containing core layer, and the shell layer comprises a hydrophilic layer covering the surface of the silicon-containing core layer and an alkaline substance covering the hydrophilic layer.)

1. A composite material for producing hydrogen, comprising:

a plurality of shell-core structures, wherein each of the shell-core structures comprises:

a silicon-containing core layer; and

a shell layer covering a surface of the silicon-containing core layer, wherein the shell layer comprises:

a hydrophilic layer coating the surface of the silicon-containing core layer; and

and an alkaline substance covering the hydrophilic layer.

2. The composite material for hydrogen production according to claim 1, wherein each of the core-shell structures is a powder.

3. The composite material for hydrogen generation according to claim 1, wherein each of the silicon-containing core layers is crystalline silicon.

4. The composite material for hydrogen generation according to claim 1, wherein each of the shell layers has at least a double-layer structure.

5. The composite material for hydrogen generation according to claim 1, wherein the composition of each hydrophilic layer comprises silicon oxide.

6. The composite material for hydrogen generation according to claim 1, wherein each of the hydrophilic layers has a thickness of 4 nm to 30 nm.

7. The composite material for hydrogen generation according to claim 1, wherein the basic substance in each shell layer directly contacts the hydrophilic layer.

8. The composite material for hydrogen generation according to claim 1, wherein the basic substance is a strongly basic substance.

9. The composite material for producing hydrogen as claimed in claim 8, wherein the strong alkaline substance is selected from the group consisting of sodium hydroxide, potassium hydroxide and lithium hydroxide.

10. The composite material for hydrogen generation as claimed in claim 1, wherein each shell layer further comprises a salt, wherein each salt covers each hydrophilic layer.

11. The composite material for hydrogen generation according to claim 10, wherein the basic substance directly contacts the salt-like substance.

12. The composite material for hydrogen generation according to claim 10, wherein the salt substance is selected from salts having a water solubility higher than 9.6 g/100 ml at 20 ℃.

13. The composite material for hydrogen production according to claim 10, wherein the cation in the salt is selected from the group consisting of lithium ion, sodium ion or potassium ion, and the anion in the salt is selected from the group consisting of chloride, carbonate, or sulfate.

14. The composite material for hydrogen generation according to claim 10, wherein the alkaline substance and the salt substance in each shell layer are uniformly mixed with each other.

15. The composite material for hydrogen generation as claimed in claim 10, wherein one of the alkaline substance and the salt substance coats the other of the alkaline substance and the salt substance.

Technical Field

The invention relates to the technical field of hydrogen preparation, in particular to a composite material for hydrogen production.

Background

In order to suppress global warming, importance is increasingly attached to the development of renewable energy technology in countries around the world. Renewable energy sources that can be used for power generation include hydrogen in addition to solar energy, geothermal energy, wind power, tides, and the like. The hydrogen is used to generate electricity, usually by burning hydrogen to generate heat energy, and the generated heat energy can be further converted into kinetic energy or electric energy. Since hydrogen only generates water without generating carbon dioxide after combustion, deterioration of global warming can be effectively avoided by generating electricity with hydrogen.

Generally, the current methods for producing hydrogen include a petrochemical fuel hydrogen production method or an electrolytic hydrogen production method. However, for the production of hydrogen by petrochemical fuel, considerable carbon dioxide is still produced in the process of producing hydrogen; for hydrogen production by electrolysis, considerable electric energy is consumed in the hydrogen production process. Therefore, the current way of producing hydrogen in the industry is still not very environmentally friendly.

Therefore, there is still a need in the art for an improved hydrogen-producing material or method that avoids the existing less environmentally friendly hydrogen-producing means.

Disclosure of Invention

According to an embodiment of the present disclosure, a composite material for hydrogen generation includes a core-shell structure, wherein the core-shell structure includes a silicon-containing core layer and a shell layer covering a surface of the silicon-containing core layer, and the shell layer includes a hydrophilic layer covering a surface of the silicon-containing core layer and a basic substance covering the hydrophilic layer.

According to an embodiment of the present disclosure, each of the shell-core structures is a powder.

According to an embodiment of the present disclosure, each of the silicon-containing core layers is crystalline silicon.

According to an embodiment of the present disclosure, each shell layer has at least a double-layer structure.

According to an embodiment of the present disclosure, the composition of the hydrophilic layer includes silicon oxide.

According to an embodiment of the present disclosure, each of the hydrophilic layers has a thickness of 4 nm to 30 nm.

According to an embodiment of the present disclosure, the alkaline substance in each shell layer directly contacts the hydrophilic layer.

According to an embodiment of the present disclosure, the alkaline substance is a strong alkaline substance.

According to an embodiment of the present disclosure, the strongly basic substance is selected from the group consisting of sodium hydroxide, potassium hydroxide, and lithium hydroxide.

According to an embodiment of the present disclosure, each shell further includes a salt material coating the hydrophilic layer.

According to an embodiment of the present disclosure, the alkaline substance directly contacts the salt substance.

According to an embodiment of the present disclosure, the salt is selected from salts having a solubility in water (20 ℃) higher than 9.6 g/100 ml.

According to an embodiment of the present disclosure, the cation of the salt is selected from the group consisting of lithium ion, sodium ion, or potassium ion, and the anion of the salt is selected from the group consisting of chloride, carbonate, or sulfate.

According to an embodiment of the present disclosure, the alkaline substance and the salt substance in each shell are uniformly mixed with each other.

According to an embodiment of the present disclosure, one of the alkaline substance and the salt substance covers the other of the alkaline substance and the salt substance.

The basic spirit and other objects of the present invention, as well as the technical means and embodiments adopted by the present invention, will be readily understood by those skilled in the art after considering the following embodiments.

Drawings

In order to make the aforementioned and other objects, features, advantages and embodiments of the invention more comprehensible, the following description is given:

FIG. 1 is a schematic diagram of a reaction system for producing hydrogen in accordance with an embodiment of the present disclosure.

FIG. 2 is a diagram of an X-ray diffraction analysis of a powder according to an embodiment of the present disclosure.

FIG. 3 is a scanning electron microscope image of a powder according to an embodiment of the disclosure.

FIG. 4 shows the results of hydrogen production for powders of examples of the present disclosure.

Description of the symbols:

100 reaction system

102 reaction cavity

104. 106 feed line

108 thermocouple

110 air outlet pipeline

112 molecular sieve

114 flow controller

116 gas collecting device

Detailed Description

In order to make the description of the invention more complete and thorough, the following illustrative description is given for implementation aspects and embodiments of the invention; it is not intended to be the only form in which the embodiments of the invention may be practiced or utilized. The embodiments are intended to cover the features of the various embodiments as well as the method steps and sequences for constructing and operating the embodiments. However, other embodiments may be utilized to achieve the same or equivalent functions and step sequences.

Although numerical ranges and parameters setting forth the broad scope of the invention are approximate, the values set forth in the specific examples are presented as precisely as possible. Any numerical value, however, inherently contains certain standard deviations found in their respective testing measurements. As used herein, "about" generally means that the actual value is within 10%, 5%, 1%, or 0.5% of a particular value or range. Alternatively, the term "about" means that the actual value falls within the acceptable standard error of the mean, subject to consideration by those of ordinary skill in the art to which the invention pertains. Except in the experimental examples, or where otherwise expressly indicated, it is to be understood that all ranges, amounts, values and percentages herein used (e.g., to describe amounts of materials, length of time, temperature, operating conditions, quantitative ratios, and the like) are to be modified by the word "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in this specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained. At the very least, these numerical parameters are to be understood as meaning the number of significant digits recited and the number resulting from applying ordinary carry notation. Here, the numerical ranges are indicated from one end point to another or between two end points; unless otherwise indicated, all numerical ranges recited herein are inclusive of the endpoints.

Unless defined otherwise herein, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Furthermore, as used herein, the singular tense of a noun, unless otherwise conflicting with context, encompasses the plural form of that noun; the use of plural nouns also covers the singular form of such nouns.

According to an embodiment of the present invention, a composite material for producing hydrogen is provided. The composite material can be in a powder state and is composed of a core-shell structure. According to one embodiment of the present disclosure, each shell-coreThe structure consists of a core layer and a shell layer wrapping the surface of the core layer, and the core layer and the shell layer have different compositions. According to an embodiment of the present disclosure, the core layer of the shell-core structure is a silicon-containing core layer mainly containing silicon, wherein the weight percentage of silicon in the silicon-containing core layer is between 80 wt.% and 100 wt.%, for example, 100 wt.% (i.e., pure silicon). Furthermore, the silicon-containing core layer may have a crystalline structure (crystaline), for example a crystalline structure comprising polycrystalline silicon and/or monocrystalline silicon. According to an embodiment of the present disclosure, the shell layer has at least a double-layer structure, which at least includes an inner hydrophilic layer and an outer alkaline substance, such that the hydrophilic layer is coated with the alkaline substance. Wherein the hydrophilic layer refers to a thin passivation layer having higher hydrophilicity than the core layer, and may include silicon oxide and have a thickness of 4 nm to 30 nm. In addition, the alkaline substance may be a salt having a solubility in water (20 ℃) higher than 12.8 g/100 ml, for example chosen from the group consisting of ammonia (NH)₃) Ammonia water (NH)₄OH), sodium bicarbonate (NaHCO)₃) The alkaline substance, or the strong alkaline substance selected from the group consisting of lithium hydroxide, sodium hydroxide and potassium hydroxide. According to another embodiment of the present disclosure, the shell layer may further include a salt substance coating the hydrophilic layer. Wherein the salt is selected from salts with solubility higher than 9.6 g/100 ml in water (20 ℃), the cation in the salt is selected from the group consisting of lithium ion, sodium ion or potassium ion, and the anion in the salt is selected from the group consisting of chloride ion, carbonate ion or sulfate ion. For example, the salt substance may be a salt such as sodium chloride or sodium sulfate, but is not limited thereto. According to an embodiment of the present disclosure, the alkaline substance and the salt substance in each shell layer may be uniformly mixed with each other, so that the alkaline substance and the salt substance may belong to a same sub-shell layer in the shell layer, and the sub-shell layer may cover the hydrophilic layer. However, according to another embodiment of the present disclosure, one of the alkaline substance and the salt substance covers the other of the alkaline substance and the salt substance, so that the alkaline substance and the salt substance can belong to adjacent sub-shells of the shell layer, and the adjacent sub-shells can still cover the hydrophilic layer.

According to the above embodiment, since the hydrophilic layer is disposed between the silicon-containing core layer and the basic substance in the composite material, the hydrophilic layer is not easily chemically reacted with the basic substance in the form of powder, so that the probability of reaction between the silicon-containing core layer and the basic substance can be reduced during the process of preparing or transporting the composite material. In addition, because the silicon-containing core layer in the composite material is at least coated by the alkaline substance, when the composite material is dispersed in a neutral or alkaline solution environment, the alkaline substance can be easily dissolved in the solution, so that the original adjacent shell-core structures can be separated from each other and completely dispersed in the solution, the probability of aggregation of the shell-core structures in the solution is reduced, and the contact area between the silicon-containing core layer and the solution is increased. In addition, because the hydrophilicity of the hydrophilic layer is higher than that of the silicon-containing core layer, polar molecules generated by the alkaline substance after dissolution can immediately wet the hydrophilic layer, and then further generate chemical reaction with the hydrophilic layer and the silicon-containing core layer, so that the composite material can rapidly generate hydrogen. Therefore, the hydrophilic layer and the alkaline substance are sequentially coated on the surface of the silicon-containing core layer, so that the probability of agglomeration of the core-shell structure can be reduced, and the composite material can generate hydrogen more quickly. Further, according to the above embodiment, by further providing a salt substance, particularly a salt substance having high solubility, in each shell layer, the composite material can be more easily dispersed in a solution, and the probability of agglomeration can be greatly reduced.

In order to make the present disclosure accessible to those skilled in the art, various embodiments of the present disclosure will be described in detail below to specifically illustrate a method for preparing a composite material for hydrogen generation and a procedure for generating hydrogen using the composite material. It should be noted that the following examples are merely illustrative and the present invention should not be construed as being limited thereto. That is, the materials used in the embodiments, the amounts and ratios of the materials, and the processing flows can be appropriately changed without departing from the scope of the present invention.

Example 1

24g of silicon powder (sigma-adrich) in the micrometer scale was taken as a core layer of the composite material for hydrogen production. And then oxidizing and growing silicon oxide on the surface of the silicon powder by utilizing an annealing mode in a vacuum environment to obtain silicon/silicon oxide powder with the powder surface coated by the silicon oxide, wherein the weight of the silicon oxide is about 8 g. Thereafter, the silicon/silicon oxide powder is added to a solution having a composition containing NaCl as well as KOH to mix the silicon/silicon oxide powder uniformly in the solution. And then quickly drying to enable NaCl and KOH to form an outer shell-shaped structure on the surface of the silicon/silicon oxide powder, or uniformly mixing the silicon/silicon oxide powder with NaCl and KOH powder in a dry manner to enable NaCl and KOH to be attached to the surface of the silicon/silicon oxide powder to form the shell-shaped structure, wherein the weight of NaCl and KOH is about 16 g. The weight ratio of the silicon/silicon oxide/NaCl + KOH powder is about 3:1:2, and in the silicon/silicon oxide/NaCl + KOH powder, the ratio of silicon is about 50 to 90 wt.%, the ratio of silicon oxide is about 0.1 to 20 wt.%, and the ratio of NaCl (salt) to KOH (alkaline substance) is about 5 to 50 wt.%.

The silicon/silicon oxide/NaCl + KOH powder can be put into a reaction system to generate and collect hydrogen. The reaction system is shown in fig. 1, and the reaction system 100 at least includes a reaction chamber 102, a feeding line 104, a feeding line 106, a thermocouple 108, an air outlet line 110, a molecular sieve 112, a flow controller 114, and a gas collecting device 116. The silicon/silicon oxide/NaCl + KOH powder may enter the reaction chamber 102 through the feeding line 104, and the water or alkaline solution may enter the reaction chamber 102 through the feeding line 106, and the solution may react in the reaction chamber 102 at normal temperature and pressure. The hydrogen produced by the reaction may be passed through a gas outlet line 110, through a molecular sieve 112 to remove excess water vapor, and then through a flow controller (M-50SLPM, Alicat)114 to a gas collection device 116.

Example 2

Example 2 is similar to example 1 above, however, the shell layer of example 2 is silica and NaCl and NaOH.

Example 3

Example 3 is similar to example 1 above, however, the shell layer of example 3 is silica and KCl and NaOH.

Example 4

Example 4 is similar to example 1 above, however, the shell layers of example 4 are silica and NaCl and LiOH.

Example 5

Example 5 is similar to example 1 above, however, the shell layer of example 5 is silica and KOH.

Example 6

Example 6 is similar to example 1 above, however, the shell of example 6 includes silica and NaOH.

Comparative example 1

Comparative example 1 is similar to example 1 above, however, the shell of comparative example 1 does not include silica, only KOH.

Comparative example 2

Comparative example 2 is similar to example 1 above, however, the shell of comparative example 2 does not include silica, only NaOH.

Comparative example 3

Comparative example 3 is similar to example 1 above, however, the shell layer of comparative example 3 is silica and NaCl.

Comparative example 4

Comparative example 4 is similar to example 1 above, however, the shell layer of comparative example 4 is silica and KCl.

Comparative example 5

Comparative example 5 is similar to example 1 above, however, the shell of comparative example 5 contains only silica.

Comparative example 6

Comparative example 6 is similar to example 1 above, however, comparative example 6 does not contain any shell layer.

Hereinafter, tests such as X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), and hydrogen production measurement will be performed on the materials of the above examples and comparative examples.

X-ray diffraction analysis

Referring to fig. 2, before forming the basic substance or the salt-like substance, the corresponding sample 3 of comparative example 5 was subjected to X-ray diffraction analysis, and it was confirmed that the core-shell structure of comparative example 5 was crystalline silicon. Referring to fig. 2, after formation of the alkaline substance and the salt substance, when the silicon/silicon oxide/NaCl + KOH powder of example 1 (sample 1) and the silicon/silicon oxide/NaCl + NaOH powder of example 2 (sample 2) were subjected to X-ray diffraction analysis, a weak NaCl crystal diffraction peak was observed, indicating that NaCl still formed crystals even when the shell was formed by flash drying.

Inspection by scanning electron microscope

Referring to fig. 3, the silicon/silicon oxide powder of example 1 was subjected to SEM morphology analysis before the formation of the alkali substance and the salt-like substance, and the result thereof is shown in fig. 3 (d). After the alkaline substance and the salt substance are formed, the silicon/silicon oxide/NaCl + KOH powder has a secondary particle size of about 2 to 10um, as shown in fig. 3(a), formed by the aggregation of the bulk material. As shown in fig. 3(b), it can be seen from a partial enlargement that the outer layer of the surface of the silicon/silicon oxide primary particles in the silicon/silicon oxide/NaCl + KOH powder has an NaCl + KOH outer shell. As shown in fig. 3(c), after forming the NaCl + KOH crust, the morphology of the silicon/silicon oxide/NaCl + KOH powder was rounded compared to the primary particles of the raw material silicon/silicon oxide, and the particle size was increased to about 200nm from the original 140nm, indicating that the NaCl + KOH crust increased the particle size.

Hydrogen production measurement

The hydrogen volumes of the hydrogen gas of examples 1 to 6 and comparative examples 1 to 6 were calculated by collecting the hydrogen gas using the reaction system shown in fig. 1, and the results are shown in fig. 4. As shown in fig. 4, the curves correspond to the hydrogen production amounts of examples 1 to 6 and comparative examples 1 to 2, respectively, along the direction of the arrow. It can be seen that, with respect to examples 1 to 4, when the shell layer of the composite material includes silicon oxide, a strong basic substance (KOH, NaOH, or LiOH), and a salt substance (KCl or NaCl), the reaction can be initiated within less than 1 minute, and a large amount of hydrogen gas can be rapidly generated, exhibiting excellent hydrogen generation efficiency. Similarly, for examples 5 and 6, when the shell layer of the composite material comprises silicon oxide, an alkaline substance (KOH, NaOH or LiOH), but does not comprise a salt substance (KCl or NaCl), the reaction can be initiated in less than 5 minutes, and a large amount of hydrogen can be rapidly generated as well.

In contrast, for comparative examples 1 and 2, when the shell layer of the composite material includes a strong basic substance (KOH, NaOH, or LiOH) but does not include silica and a salt substance (KCl or NaCl), the waiting time for the initiation reaction is longer. Also, for comparative examples 3 to 6, when the shell layer of the composite material does not include any alkaline substance (KOH, NaOH, or LiOH), even if it does not include the shell layer, the time to initiate the reaction is more than 30 minutes.

According to the above embodiment, since the composite material is solid, it is easy to transport. In addition, because the hydrophilic layer is arranged between the silicon-containing core layer and the alkaline substance in the composite material, the hydrophilic layer is not easy to react with the alkaline substance in a powder form, and therefore, the probability of the reaction between the silicon-containing core layer and the alkaline substance can be reduced in the process of preparing or transporting the composite material. In addition, because the silicon-containing core layer in the composite material is at least coated by the alkaline substance, when the composite material is dispersed in a neutral or alkaline solution environment, the alkaline substance can be easily dissolved in the solution, so that the original adjacent shell-core structures can be separated from each other and completely dispersed in the solution, the probability of aggregation of the shell-core structures in the solution is reduced, and the contact area between the silicon-containing core layer and the solution is increased. In addition, because the hydrophilicity of the hydrophilic layer is higher than that of the silicon-containing core layer, polar molecules generated by the alkaline substance after dissolution can immediately wet the hydrophilic layer, and then the polar molecules can further generate chemical reactions with the hydrophilic layer and the silicon-containing core layer, so that the composite material can quickly generate hydrogen, and the starting time is shortened. Therefore, by coating the alkaline substance on the surface of the silicon-containing core layer, the probability of agglomeration of the core-shell structure can be reduced, and the composite material can generate hydrogen more quickly. In addition, after the hydrogen production process is finished, the residual product is silicon oxide or silicate, and the recovery is easy.