Thermoelectric composite materials and their preparation methods and applications

Abstract

The present application relates to the technical field of new energy materials, and in particular to thermoelectric composite materials, preparation methods and applications thereof. The thermoelectric composite materials include 2D TMDs, P-type semiconductor polymers, and conductive polymers. The P-type semiconductor polymers and conductive polymers are cross-linked to form a composite conductive polymer, and the 2D TMDs are dispersed in the composite conductive polymer. The composite conductive polymer has the functions of forming a thermoelectric circuit, regulating and modifying the interface of 2D TMDs, and protecting the 2D TMDs dispersed therein. The 2D TMDs and the P-type semiconductor polymer convert thermal energy into electrical energy under the Seebeck effect. Thermoelectric building material additives include thermoelectric composite materials combined with inorganic silica gel carriers. Thermoelectric cement-based materials include cement and thermoelectric building material additives. The thermoelectric cement-based material has good thermoelectric performance, stability and durability, and is suitable for scenarios with significant temperature differences or urgent energy recovery needs.

Description

Technical Field

[0001] The present application relates to the technical field of new energy materials, and in particular to thermoelectric composite materials and preparation methods and applications thereof. Background Art

[0002] Thermoelectric conversion materials are materials that can convert heat into electricity, primarily through the Seebeck effect, where a temperature difference generates an electric current. Existing thermoelectric conversion materials typically include bismuth telluride (Bi2Te3) and its alloys, lead telluride (PbTe) and its alloys, bismuth-antimony alloys, and organic / polymer thermoelectric materials. Suitable options are available for each application scenario.

[0003] At the same time, in scenarios with significant temperature differences or urgent energy recovery needs, such as industrial waste heat recovery, transportation infrastructure, and special environment buildings, there is a large demand for thermoelectric conversion. If the corresponding building materials have thermoelectric conversion properties, a large amount of electricity can be obtained. However, existing thermoelectric materials are often difficult to apply to building materials. First, the thermoelectric conversion efficiency of existing thermoelectric materials is low, the power generation capacity used in building materials is low, and the economic efficiency is poor; second, thermoelectric materials are often expensive, and the cost of using them in building materials is high; third, thermoelectric materials have poor long-term stability and durability. They will oxidize and undergo phase changes in harsh environments such as high temperature and rain. If thermoelectric materials are subjected to pressure and impact in buildings, they are easily damaged, affecting their thermoelectric performance; finally, thermoelectric materials have poor compatibility with building materials and cannot be well combined in building materials and buildings. Blindly adding them may even affect the mechanical strength and structural stability of building materials.

[0004] Considering the above economic and technical factors, there is little research on existing thermoelectric materials in building materials, and there is an even greater lack of thermoelectric materials suitable for building materials. Summary of the Invention

[0005] The purpose of this application is to provide a thermoelectric composite material and its preparation method and application, aiming to solve the problem that the thermoelectric composite material in the prior art has low performance and is difficult to use as a building material.

[0006] To achieve the above application objectives, the technical solutions adopted in this application are as follows:

[0007] In a first aspect, the present application provides a thermoelectric composite material, comprising a two-dimensional transition metal dichalcogenide compound (hereinafter referred to as 2D TMDs), a P-type semiconductor polymer, and a conductive polymer. The P-type semiconductor polymer and the conductive polymer are cross-linked to form a composite conductive polymer, and the 2D TMDs are dispersed in the composite conductive polymer.

[0008] The thermoelectric composite material in this application includes N-type semiconductor materials such as 2D TMDs with a high Seebeck coefficient, and also includes P-type semiconductor polymers. Under the temperature difference, the two semiconductors form an electromotive force in the loop due to the Seebeck effect, generating thermoelectric current and realizing thermoelectric conversion. The thermoelectric composite material also includes a conductive polymer, which is cross-linked with a P-type semiconductor polymer to form a composite conductive polymer, and 2D TMDs are dispersed in the composite conductive polymer. In this composite method, the conductive polymer has good conductivity, so that the cross-linked composite conductive polymer forms a continuous cross-linked conductive network. On the one hand, the composite conductive polymer and the 2D TMDs dispersed therein constitute the above-mentioned circuit. Only by forming a circuit can the Seebeck effect be generated, so that the electrons in the 2D TMDs and the holes in the P-type semiconductor polymer migrate from the hot end to the cold end to form an electric current; on the other hand, the cross-linked network structure of the composite conductive polymer has a good interface regulation and modification effect on the 2D TMDs dispersed therein, which not only improves the stability of its layered structure and enables the material to fully exert its thermoelectric properties, but also significantly improves the generally low out-of-plane conductivity of 2D TMDs, and synergistically with the high conductivity of the cross-linked conductive network itself, so that the entire thermoelectric composite material has a higher electrical conductivity, improves the thermoelectric figure of merit ZT, and improves the thermoelectric conversion performance; on the other hand, the 2D TMDs dispersed in the composite conductive polymer reduce their contact with the external environment, improve the 2D The stability of TMDs materials also improves the compatibility of the entire thermoelectric composite material with the silicate material system and can be used in building materials.

[0009] In a second aspect, the present application provides a method for preparing the thermoelectric composite material of the above application, comprising the following steps:

[0010] The raw materials including the two-dimensional transition metal dichalcogenide compound and the composite conductive polymer are subjected to a first mixing process to obtain a thermoelectric composite material.

[0011] The preparation method of the present application subjects the corresponding raw materials to a first mixing process, dispersing the 2D TMDs in a composite conductive polymer to produce the aforementioned thermoelectric composite material, which can convert thermal energy into electrical energy and can be used in building materials. The preparation method is process-controllable, and the structure and physicochemical properties of the obtained thermoelectric composite material are stable.

[0012] In a third aspect, the present application provides a thermoelectric building material additive, including an inorganic silica gel carrier, and also including the thermoelectric composite material of the above application or the thermoelectric composite material prepared by the preparation method of the above application, and the thermoelectric composite material is combined on the inorganic silica gel carrier.

[0013] The thermoelectric building material additive of the present application contains the above-mentioned thermoelectric composite material, and therefore has good thermoelectric conversion performance and stability. The thermoelectric composite material is further loaded on an inorganic silica gel carrier. On the one hand, the physical adsorption and protection of the porous structure of the inorganic silica gel carrier is conducive to further improving the stability of the thermoelectric composite material; on the other hand, the main component of the inorganic silica gel is amorphous silicon dioxide, which has high chemical activity and will chemically combine with the thermoelectric composite material, further improving the stability of the combination; on the other hand, inorganic silica gel has good compatibility with most building materials. The thermoelectric building material additive can be better used in building materials to play a thermoelectric conversion role.

[0014] In a fourth aspect, the present application provides a method for preparing the thermoelectric building material additive of the above-mentioned application, comprising the following steps:

[0015] The thermoelectric composite material and the inorganic silica gel carrier are subjected to a second mixing treatment.

[0016] The thermoelectric building material additive described in this application undergoes a secondary mixing process with a thermoelectric composite material and an inorganic silica-based carrier. Through porous adsorption and chemical bonding, the thermoelectric composite material is fully bonded to the inorganic silica-based carrier. The resulting thermoelectric building material additive exhibits excellent thermoelectric conversion performance and stability, and is highly compatible with building materials, enabling its use in building materials to achieve thermoelectric conversion. The preparation method is process-controllable, and the resulting thermoelectric building material additive exhibits stable structure and physicochemical properties.

[0017] In a fifth aspect, the present application provides a thermoelectric cement-based material, comprising cement, and also comprising the thermoelectric building material additive of the above application or the thermoelectric building material additive prepared by the preparation method of the above application.

[0018] The thermoelectric cement-based material of the present application includes the aforementioned thermoelectric building material additive. Its excellent stability and compatibility with cement facilitate its dispersibility in cement-based materials, making it suitable for use as a component in building materials. Furthermore, the thermoelectric building material additive exhibits excellent thermoelectric conversion performance, imparting corresponding properties to the thermoelectric cement-based material, enabling its use in relevant construction projects to convert thermal energy into electrical energy, thereby achieving clean energy conversion and utilization. DETAILED DESCRIPTION

[0019] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0020] In this application, the term "and / or" describes the relationship between associated objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0021] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items.

[0022] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. Some or all of the steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0023] The weights of the relevant components mentioned in the examples of this application may not only refer to the specific content of each component, but also represent the weight ratio between the components. Therefore, as long as the content of the relevant components is proportionally increased or decreased according to the examples of this application, it is within the scope disclosed in the examples of this application. Specifically, the mass in the examples of this application may be a mass unit known in the chemical industry, such as μg, mg, g, kg, etc.

[0024] The terms "first" and "second" are used solely for descriptive purposes to distinguish objects, such as substances, from one another and should not be understood to indicate or imply relative importance or to implicitly specify the quantity of the technical features being referred to. For example, without departing from the scope of the embodiments of this application, a first XX may also be referred to as a second XX, and similarly, a second XX may also be referred to as a first XX. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more of such features.

[0025] The thermoelectric conversion performance of thermoelectric materials is mainly reflected by the thermoelectric figure of merit ZT, and the thermoelectric figure of merit calculation formula is: ZT = S 2 σT / κ, where S is the Seebeck coefficient of the material (reflecting the thermoelectric potential), σ is the electrical conductivity of the material, T is the absolute temperature, and κ is the thermal conductivity of the material. 2σ, also known as the power factor (PF), characterizes the electrical properties of thermoelectric materials. T / κ characterizes the thermal properties of thermoelectric materials. Thermal conductivity (κ) is composed of lattice thermal conductivity and electronic thermal conductivity. As can be seen, to improve the efficiency of converting heat into electricity, thermoelectric materials require a high Seebeck coefficient and electrical conductivity, while a low thermal conductivity is required. This is because, on the one hand, some of the heat from the heat source is converted into electricity, and some is transported to the cold end. Higher thermal conductivity means more heat is wasted. On the other hand, the Seebeck effect requires a temperature difference between the two ends of the material, and a higher thermal conductivity makes this more difficult. Based on the thermoelectric figure of merit (ZT), other parameters such as thermoelectric conversion efficiency can be further calculated. Therefore, the thermoelectric conversion performance of thermoelectric materials requires a high ZT. Existing thermoelectric materials often struggle to balance the three aforementioned factors: the Seebeck coefficient, electrical conductivity, and thermal conductivity. In particular, materials with high electrical conductivity often also have high thermal conductivity, making it difficult to simultaneously increase electrical conductivity and reduce thermal conductivity. This underlying contradiction creates room for further improvement in the ZT. Moreover, existing thermoelectric materials still have problems such as stability, durability, and compatibility, making it difficult to use them in building materials.

[0026] In a first aspect, an embodiment of the present application provides a thermoelectric composite material, including a two-dimensional transition metal dichalcogenide compound (hereinafter referred to as 2D TMDs), a P-type semiconductor polymer, and a conductive polymer. The P-type semiconductor polymer and the conductive polymer are cross-linked to form a composite conductive polymer, and the 2D TMDs are dispersed in the composite conductive polymer.

[0027] The thermoelectric composite material in the embodiment of the present application includes N-type semiconductor materials such as 2D TMDs with a high Seebeck coefficient, and also includes P-type semiconductor polymers. Under the temperature difference, the two semiconductors form an electromotive force in the loop due to the Seebeck effect, generating thermoelectric current and realizing thermoelectric conversion. The thermoelectric composite material also includes a conductive polymer, which is cross-linked with a P-type semiconductor polymer to form a composite conductive polymer, and 2D TMDs are dispersed in the composite conductive polymer. In this composite method, the conductive polymer has good conductivity, so that the cross-linked composite conductive polymer forms a continuous cross-linked conductive network. On the one hand, the composite conductive polymer and the 2D TMDs dispersed therein constitute the above-mentioned circuit. Only by forming a circuit can the Seebeck effect be generated, so that the electrons in the 2D TMDs and the holes in the P-type semiconductor polymer migrate from the hot end to the cold end to form an electric current; on the other hand, the cross-linked network structure of the composite conductive polymer has a good interface regulation and modification effect on the 2D TMDs dispersed therein, which not only improves the stability of its layered structure and enables the material to fully exert its thermoelectric properties, but also significantly improves the generally low out-of-plane conductivity of 2D TMDs, and synergistically with the high conductivity of the cross-linked conductive network itself, so that the entire thermoelectric composite material has a higher electrical conductivity, improves the thermoelectric figure of merit ZT, and improves the thermoelectric conversion performance; on the other hand, the 2D TMDs dispersed in the composite conductive polymer reduce their contact with the external environment, improve the 2D The stability of TMDs materials also improves the compatibility of the entire thermoelectric composite material with the silicate material system and can be used in building materials.

[0028] About 2D TMDs:

[0029] The 2D TMDs in the thermoelectric composite material of the present application are typical N-type semiconductors with a high Seebeck coefficient, which is beneficial to improving the thermoelectric conversion performance of the thermoelectric composite material of the present application. The chemical formula of 2D TMDs is MX2, where M is a transition metal and X is a chalcogen element. The layers are covalently bonded by XMX, and the layers are bonded by weak van der Waals forces. They have significant electrical and thermal anisotropy, and electrons are easy to migrate between layers, and the interlayer conductivity is strong. However, the electrical conductivity σ and thermal conductivity κ in the out-of-plane direction are usually much lower than those in the in-plane direction. Although the low thermal conductivity κ in the out-of-plane direction is beneficial to improving the thermoelectric figure of merit ZT, the low electrical conductivity σ in the out-of-plane direction is not conducive to improving the thermoelectric figure of merit ZT. The interface regulation effect of the above-mentioned composite conductive polymer greatly improves its out-of-plane conductivity, makes up for this shortcoming, and improves the thermoelectric figure of merit ZT.

[0030] In some embodiments, 2D TMDs may include at least one of molybdenum disulfide, tungsten disulfide, molybdenum diselenide, and molybdenum ditelluride, with molybdenum disulfide being an option. These 2D TMDs have the properties of the aforementioned materials and can be used in conjunction with composite conductive polymers to further improve thermoelectric conversion performance. Among them, molybdenum disulfide has ideal thermoelectric properties. First, it has a high Seebeck coefficient; second, it has low thermal conductivity (about 1.6 W / m·K), which can reduce heat flow loss and improve thermoelectric conversion efficiency; third, it has high electron mobility (about 200 cm 2 / V·s), good electron transport performance, which is beneficial to improving the power factor S of thermoelectric materials 2 σ; Fourth, its structure and physicochemical properties are more stable in comparison. It is not easy to hydrolyze and oxidize in the air and other environments. It is suitable for long-term use in building materials, which is conducive to giving thermoelectric composite materials the above-mentioned ideal properties.

[0031] In one embodiment, 2D TMDs include molybdenum disulfide (MoS2), wherein the number of MoS2 layers is 2 to 5 and the interlayer spacing is approximately 0.615 nm. MoS2 with these layered structural parameters further enhances its thermoelectric performance, thereby improving the thermoelectric performance of thermoelectric composite materials. In one embodiment, the MoS2 crystal form can be at least one of 2H, 1T, and 1T'. The 2H phase is a thermodynamically stable semiconductor phase with a moderate band gap, which is beneficial for improving the Seebeck coefficient; the 1T phase is a metallic phase with higher electron mobility, which is beneficial for improving the electrical conductivity σ; and the 1T' phase exhibits spin-orbit coupling, which can enhance the electronic density of states, thereby improving thermoelectric performance. In one embodiment, the MoS2 can be polycrystalline, with the 2H phase being the primary phase. In one embodiment, MoS2 nanoparticle morphologies such as nanosheets, nanospheres, and nanoflowers can also enhance specific surface area and promote heat and electron migration.

[0032] In an embodiment, the mass percentage of 2D TMDs in the thermoelectric composite material can be 15% to 25%, including but not limited to any value of 15%, 17%, 20%, 22%, 25%, or a range between any two values. These contents of 2D TMDs are beneficial to further improve the thermoelectric conversion performance of the entire thermoelectric composite material.

[0033] About composite conductive polymers:

[0034] Composite conductive polymers are formed by crosslinking a p-type semiconducting polymer and a conductive polymer. The conductive polymer imparts excellent electrical conductivity to the composite, forming a continuous crosslinked conductive network. This network facilitates thermoelectric circuit formation, modifies the interface of 2D TMDs, and protects the dispersed 2D TMDs. This synergistic effect with the 2D TMDs results in a high thermoelectric figure of merit (ZT) for the entire thermoelectric composite. The p-type semiconducting polymer and conductive polymer components are discussed below.

[0035] About the P-type semiconductor polymer:

[0036] P-type semiconducting polymers primarily transport holes as charge carriers, synergizing with 2D TMDs to produce the Seebeck effect, converting thermal energy into electrical energy. Furthermore, 2D TMDs are N-type semiconductors with negative Seebeck coefficients. The P-type semiconducting polymers synergize with them through heterojunction energy filtering and carrier concentration balance, enhancing the energy filtering effect on electrons. This facilitates more efficient directional electron movement under thermal gradients, resulting in the overall thermoelectric composite material exhibiting a more negative Seebeck coefficient, meaning its absolute value increases. The absolute value of the Seebeck coefficient is positively correlated with the thermoelectric figure of merit (ZT) and output power density, further enhancing the thermoelectric conversion performance of the overall thermoelectric composite material. In some embodiments, the mass percentage of the P-type semiconducting polymer in the thermoelectric composite material can be 15% to 25%. This helps to further achieve an appropriate ratio of N-type and P-type semiconductors to produce the Seebeck effect, synergistically increasing the absolute value of the Seebeck coefficient and improving thermoelectric conversion performance.

[0037] In some embodiments, the P-type semiconductor polymer may include at least one of polyaniline (polyaniline and its derivatives), polythiophene (polythiophene and its derivatives), and polypyrrole (polypyrrole and its derivatives). These materials are intrinsic P-type semiconductors. In addition to leveraging the fundamental properties of these semiconductor materials, their hole transport properties can generally be further enhanced through doping or derivative design. Polythiophenes offer superior overall performance but are relatively expensive. Polyanilines are easy to modify through doping, improve conductivity, and have good compatibility with cement, but their thermal stability and durability are lower than those of polythiophenes. Polypyrroles offer strong conductivity but are less chemically stable than the aforementioned two materials, making them unsuitable for long-term applications.

[0038] P-type semiconductor polymers can also have certain conductivity and properties of conductive polymers depending on their doping control or derivative types. In this case, P-type semiconductor polymers also have some of the following technical effects of conductive polymers.

[0039] About the conductive polymer:

[0040] Conductive polymers possess both high electrical conductivity and a specific three-dimensional spatial structure. First, the intrinsic charge transport properties of p-type semiconducting polymers are generally low, requiring doping or, as mentioned above, derivatives to improve their performance. Crosslinking and modifying conductive polymers with p-type semiconducting polymers can enhance their charge transport properties and improve their conductivity. Second, the resulting composite conductive polymer can play the aforementioned role in forming thermoelectric circuits, regulating and modifying the interface of 2D TMDs, and protecting 2D TMDs to enhance compatibility.

[0041] In some embodiments, the weight percentage of the conductive polymer in the thermoelectric composite material is 60% to 75%, including but not limited to any value of 60%, 65%, 70%, or 75%, or any range between any two values. In some embodiments, the conductive polymer can include at least one of acidified chitosan, a lignin-based composite conductive polymer, and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). These conductive polymer contents and types further facilitate the aforementioned improvements in thermoelectric performance. Among them, acidified chitosan is a modified material that forms a conductive structure after doping acid with almost non-conductive chitosan. It can provide a continuous three-dimensional conductive network. On the one hand, it can cross-link with P-type semiconductors to form a three-dimensional cross-linked conductive network, thereby enhancing the electron transmission ability between 2D TMDs dispersed in the composite conductive polymer; on the other hand, the molecular structure of acidified chitosan is a flexible network, which can improve the mechanical properties of the entire thermoelectric composite material, improve the stability of the combination of various materials, and further play a certain interface regulation role between the layers and outside the surface of 2D TMDs, thereby optimizing the thermoelectric performance; on the other hand, as a biomass-based material, acidified chitosan is green and environmentally friendly. In addition to acidified chitosan, lignin-based composite conductive polymers also have similar effects.

[0042] Optionally, the 2D TMDs include molybdenum disulfide, a p-type semiconducting polymer including polyaniline, and a conductive polymer including acidified chitosan. The acidified chitosan crosslinks and modifies the polyaniline, forming a composite conductive polymer in which molybdenum disulfide is dispersed. The molybdenum disulfide is then modified for out-of-plane conductivity and interface regulation. The molybdenum disulfide reacts with the polyaniline to produce a Seebeck effect, resulting in the overall thermoelectric composite material exhibiting superior thermoelectric conversion performance, structural stability, and durability.

[0043] A second aspect of the present application provides a method for preparing the thermoelectric composite material according to the above application embodiment, comprising the following step S10:

[0044] S10: performing a first mixing process on raw materials including a two-dimensional transition metal dichalcogenide compound and a composite conductive polymer to obtain a thermoelectric composite material.

[0045] The preparation method of the present application embodiment involves first mixing the corresponding raw materials to disperse the 2D TMDs in a composite conductive polymer to produce the aforementioned thermoelectric composite material, which can convert thermal energy into electrical energy and can be used in building materials. The preparation method is process-controllable, and the resulting thermoelectric composite material has stable structure and physicochemical properties. The composite conductive polymer refers to the composite conductive polymer contained in the thermoelectric composite material of the above-mentioned application, which is formed by cross-linking a P-type semiconductor polymer and a conductive polymer.

[0046] In an embodiment, the above step S10 may further include the following steps S11 to S13:

[0047] S11: Provide 2D TMDs;

[0048] S12: Preparation of composite conductive polymers;

[0049] S13: Perform the above-mentioned first mixing process.

[0050] The preparation method of 2D TMDs in step S11 may include hydrothermal reduction, chemical vapor deposition, etc., and the hydrothermal reduction method can be selected, which is conducive to the preparation of high-purity nano-morphological 2D TMDs, increasing the specific surface area, promoting heat migration and electron migration, and the hydrothermal reduction process and materials are relatively green and environmentally friendly. Taking the preparation of molybdenum disulfide as an example, the molybdenum source of the hydrothermal reduction method can be water-soluble MoCl5 or (NH4)2MoS4, the sulfur source can be water-soluble thiourea, the solvent can be deionized water and ethanol, and the reducing agent can be ethanol. The molybdenum source and thiourea can be first dissolved in a solvent composed of ethanol and deionized water, and then heated at about 180°C after sufficient stirring to generate a reduction reaction to generate molybdenum disulfide. If the temperature is too low, the reaction may not be complete to generate amorphous MoS x If the temperature is too high, MoO3 impurities may be generated. After the reaction is completed, other residual substances are washed away with ethanol and deionized water, and the precipitate is collected and dried in a vacuum at 60°C to obtain molybdenum disulfide nanosheets.

[0051] Step S12 is the step of cross-linking the P-type semiconductor polymer and the conductive polymer to prepare a composite conductive polymer. The two can be directly physically mixed and cross-linked via intermolecular forces. To further increase the degree of cross-linking, monomers of the P-type semiconductor polymer can also be mixed with the conductive polymer and then polymerized in situ. In an embodiment, the method for preparing the composite conductive polymer includes the following steps: using the conductive polymer as a template, subjecting the monomers of the P-type semiconductor polymer to an oxidative polymerization reaction, resulting in a polymer, namely, a P-type semiconductor polymer. In this method, because the conductive polymer serves as a template, the polymerization process can be guided, facilitating the in situ polymerization of the monomers on the P-type semiconductor polymer, resulting in the P-type semiconductor polymer and the conductive polymer forming a highly cross-linked three-dimensional structure, thereby obtaining the composite conductive polymer. The enzyme can be horseradish peroxidase (HRP), the oxidant can be hydrogen peroxide, and the monomers of the P-type semiconductor polymer can include at least one of aniline, thiophene, and pyrrole. A conductive polymer, such as chitosan, can be dissolved in deionized water, and the pH can be adjusted with a protonic acid, such as hydrochloric acid, to a pH of 6.5. The protonic acid not only creates a reaction environment but also acidifies the chitosan, improving its conductivity. It can also dope and modify the resulting P-type semiconducting polymer, improving its conductivity. An enzyme and an oxidant are added to the conductive polymer solution, followed by monomers. The oxidative polymerization reaction is carried out by stirring at room temperature. HRP and the oxidant act together to catalyze the polymerization of the monomers into a P-type semiconducting polymer. The conductive polymer serves as a template, allowing the monomers to polymerize in situ on the conductive polymer. This results in a high degree of crosslinking between the P-type semiconducting polymer and the conductive polymer, forming a composite conductive polymer. This facilitates the formation of the thermoelectric circuit, the control and modification of the 2D TMD interface, and the protection of the 2D TMDs dispersed therein.

[0052] S13 is the step of mixing the 2D TMDs with the composite conductive polymer. The 2D TMDs from step S11 can be added to the sol after the reaction in step S12 and stirred thoroughly. During this process, the 2D TMDs and the composite conductive material enhance their mutual binding strength through methods such as hydrogen bonding, electrostatic adsorption, and π-π bonding. For example, in the composite conductive material containing acidified chitosan, the amino and hydroxyl groups in its molecules can form hydrogen bonds with defect sites on the surface of the 2D TMDs or adsorbed water molecules. Acidified chitosan is cationic under weakly acidic to neutral conditions, and the 2D TMDs tend to have a negative surface charge in water / ethanol solvents, leading to electrostatic adsorption between the two. The composite conductive material also forms a π-π bond stacking effect with the 2D TMDs' layered structure, enhancing interfacial bonding.

[0053] The first mixing process allows the 2D TMDs to be fully dispersed and fully encapsulated in the conductive polymer, further improving their stability and producing a thermoelectric composite material. This thermoelectric composite material can remain in a sol state, facilitating uniform dispersion and sufficient bonding. It can also be dried to a powdered form, such as by drying at 80°C for 12 hours. This powdered thermoelectric composite material is easy to store and transport, further improving stability and facilitating metering, which facilitates adaptability and standardization within a modular process.

[0054] The third aspect of the embodiments of the present application provides a thermoelectric building material additive, including an inorganic silica gel carrier, and also including the thermoelectric composite material of the above embodiment of the application or the thermoelectric composite material prepared by the preparation method of the above embodiment of the application, and the thermoelectric composite material is combined on the inorganic silica gel carrier.

[0055] The thermoelectric building material additive in the embodiment of the present application contains the above-mentioned thermoelectric composite material, and therefore has good thermoelectric conversion performance and stability. The thermoelectric composite material is further loaded on an inorganic silica gel carrier. On the one hand, the physical adsorption and protection of the porous structure of the inorganic silica gel carrier is conducive to further improving the stability of the thermoelectric composite material; on the other hand, the main component of the inorganic silica gel is amorphous silicon dioxide, which has high chemical activity and will chemically combine with the thermoelectric composite material, further improving the stability of the combination; on the other hand, inorganic silica gel has good compatibility with most building materials. The thermoelectric building material additive can be better used in building materials to play a thermoelectric conversion role.

[0056] In the embodiment, the mass percentage of the thermoelectric composite material in the thermoelectric building material additive is 5% to 8%, which further enables the thermoelectric building material additive to have the desired thermoelectric conversion performance and good compatibility with building materials. In the embodiment, the inorganic silica gel carrier can include at least one of acid-activated waste concrete and dried silica gel. In the embodiment, the inorganic silica gel carrier can be prepared by drying silica gel. In the embodiment, it can also be prepared by acid activation of construction solid waste such as waste concrete, which is beneficial to reducing resource waste, recycling waste resources, reducing the impact of construction solid waste on the environment, and promoting sustainable development; it also takes into account the balance between high active surface and gelling properties; and has the advantage of low-cost raw materials.

[0057] A fourth aspect of the present application provides a method for preparing the thermoelectric building material additive of the above-mentioned embodiment, comprising the following steps:

[0058] G10: performing a second mixing treatment on the thermoelectric composite material and the inorganic silica gel carrier.

[0059] The thermoelectric building material additive of this embodiment of the application undergoes a second mixing process with a thermoelectric composite material and an inorganic silica-based carrier. Through porous adsorption and chemical bonding, the thermoelectric composite material is fully bonded to the inorganic silica-based carrier. The resulting thermoelectric building material additive exhibits excellent thermoelectric conversion performance and stability, and is highly compatible with building materials, enabling its use in building materials to achieve thermoelectric conversion. The preparation method is process-controllable, and the resulting thermoelectric building material additive exhibits stable structure and physicochemical properties.

[0060] In an embodiment, step G10 may include the following steps G11 to G12:

[0061] G11: Provides inorganic silica gel carriers;

[0062] G12: Perform the above-mentioned second mixing process.

[0063] The inorganic silica gel carrier in step G11 can be prepared by heating and drying silica gel. Depending on the degree of drying, the water content can be retained to varying degrees, allowing parameters such as the carrier's porosity to be controlled. It can also be prepared from activated construction solid waste, such as waste concrete. This not only contains the inorganic silica gel carrier but also exhibits good compatibility with building materials. In an embodiment, the collected waste concrete can be first crushed, using a crusher to reduce particles to a size of 0-1 mm, and then screened. The collected waste concrete can then be fed into a screening device to screen out fine powder with a Dv50 particle size ≤ 0.5 mm to enhance subsequent loading and modification. The screened waste concrete fine powder is then cleaned and acid-activated. It is first soaked in an acidic impurity removal solution, such as dilute hydrochloric acid or sulfuric acid, to remove chemical impurities from the waste concrete. Simultaneously, the acid activates the surface of the waste concrete fine powder, promoting surface porosity and improving the material's adsorption capacity. Alkaline components such as calcium carbonate, calcium hydroxide, and aluminosilicate react to form amorphous silica, enhancing chemical reactivity. Finally, high-temperature drying and activation are carried out. The product after fine powder acidification can be filtered and the filter residue is heated to 300 °C under a nitrogen atmosphere and dried for 24 h to further improve the chemical activity of the concrete powder.

[0064] The second mixing treatment in step G12 can be performed by mechanical stirring, ultrasonic dispersion, or other methods to thoroughly mix the thermoelectric composite material and the inorganic silica gel carrier. In an embodiment, the inorganic silica gel carrier can be thoroughly dispersed in a water / ethanol mixed solvent before being added to the thermoelectric composite material. The mass ratio of the inorganic silica gel carrier to the thermoelectric composite material can be (10-25):1, or can be further (11.5-19):1. Thorough mixing and stirring can be performed. Ultrasonic waves can be further applied at a power of 200 W and a frequency of 40 kHz. After ultrasonic treatment, the mixture is allowed to stand to enhance the dispersion and bonding between the inorganic silica gel carrier and the thermoelectric composite material. In addition to physical adsorption and chemical bonding, electrostatic adsorption can also occur depending on the type of inorganic silica gel carrier to further enhance the bonding effect. For example, the surface of acid-activated waste concrete is rich in –SiO - , –AlO - The above-mentioned thermoelectric composite materials often have a positive charge as a whole, resulting in electrostatic adsorption. Therefore, acid-activated waste concrete as an inorganic silica gel carrier can provide a stable load-bearing platform for the thermoelectric composite material, improving the binding stability of the thermoelectric building material additive. After the thermoelectric building material additive is prepared, it can be further dried to prepare a powder for use, for example, by drying at 80°C for 12 hours.

[0065] A fifth aspect of the embodiments of the present application provides a thermoelectric cement-based material, including cement, and also including the thermoelectric building material additive of the above embodiments of the present application or the thermoelectric building material additive prepared by the preparation method of the above embodiments of the present application.

[0066] The thermoelectric cement-based material of the present application includes the aforementioned thermoelectric building material additive. Its excellent stability and compatibility with cement facilitate its dispersibility within the cement-based material, making it suitable for use as a component in building materials. Furthermore, the thermoelectric building material additive exhibits excellent thermoelectric conversion performance, imparting corresponding properties to the thermoelectric cement-based material, enabling its use in relevant construction projects to convert thermal energy into electrical energy, achieving clean energy conversion and utilization.

[0067] In some embodiments, the thermoelectric cement-based material may be in the form of a powder, such as a mixture of a thermoelectric building material additive and cement, which is then mixed with sand and water before use. In some embodiments, the thermoelectric cement-based material may also be in the form of a slurry. In some embodiments, the thermoelectric cement-based material may include the following components in parts by weight:

[0068] 0.1-0.2 parts of thermoelectric building material additives;

[0069] 0.8-0.9 parts of cement;

[0070] 3 parts sand;

[0071] 0.33-0.36 parts of water;

[0072] Water reducing agent 0.009-0.012 parts.

[0073] In this embodiment, cement can be selected from Portland cement, ordinary Portland cement, etc., depending on the desired cement-based material's properties. Sand can include machine-made sand, cleaned river sand, standard sand, etc., and the water reducer can include polycarboxylate water reducer, etc. The mix ratio can be designed according to a cement:sand:water ratio of 1:3:0.35. The thermoelectric building material can be substituted for Portland cement at a mass fraction of 10% to 20%. The resulting thermoelectric cement-based material at these mass fractions exhibits optimal thermoelectric conversion performance. During preparation, if the thermoelectric building material additive is in powder form, it can be thoroughly mixed with cement, then formulated into a slurry with sand, water, and a water reducer to uniformly disperse all components to obtain the thermoelectric cement-based material. Finally, the slurry can be cast and cured. During the cement hydration reaction and curing process, the inorganic silica gel carrier of the thermoelectric building material additive will also participate to a certain extent in the reaction, allowing the thermoelectric composite material to be evenly and firmly dispersed in the cured cement, fully realizing its thermoelectric conversion performance and preventing agglomeration or localized low concentrations that could affect performance, such as short circuits.

[0074] Components made from thermoelectric cement-based materials, or thermoelectric composite materials incorporated into buildings, typically generate current locally. Therefore, when preparing the slurry, certain amounts of metal particles and conductive carbon materials can be added to further enhance the continuous distribution of the conductive network within the cement. Energy collection can be achieved through electrodes or conductive coatings, and further design can be combined with circuit design, energy management technology, and energy storage devices to meet energy storage requirements.

[0075] If components or buildings made from thermoelectric cement-based materials strictly adhere to IEC / GB standards, utilize new environmentally friendly materials, and implement active monitoring, the potential risks associated with electricity generated by thermoelectric buildings can be controlled. These risks are significantly lower than those associated with lead-acid batteries in traditional photovoltaic systems or CO leakage in gas-fired heating systems, placing them at risk level B for green buildings, a relatively low tolerable risk. Therefore, thermoelectric cement-based materials are suitable for applications with significant temperature differences or urgent energy recovery needs, such as industrial waste heat recovery, transportation infrastructure, and buildings in special environments.

[0076] The following describes the details in conjunction with specific embodiments.

[0077] Example A1

[0078] This embodiment provides a thermoelectric composite material and a preparation method thereof, the preparation method comprising the following steps S1 to S3:

[0079] S1: Preparation of MoS2 Nanosheets by Hydrothermal Reduction

[0080] Raw materials: molybdenum source (MoCl5), sulfur source (thiourea), deionized water, ethanol;

[0081] MoCl₅ and thiourea were dissolved in 100 mL of ethanol and 20 mL of deionized water and stirred for 30 minutes, resulting in a solution with a MoCl₅ concentration of 0.2 M and a thiourea concentration of 0.4 M. The solution was transferred to a 200 mL polytetrafluoroethylene reactor and reacted at 180°C for 12 hours. The precipitate was washed three times with ethanol and deionized water, and then vacuum-dried at 60°C to obtain MoS₂ nanosheets.

[0082] S2: Preparation of composite conductive materials by enzyme-catalyzed polymerization

[0083] Raw materials: chitosan, peroxidase (HRP), oxidant (H2O2), aniline;

[0084] 0.5 g of chitosan was dissolved in 10 mL of deionized water, and the pH of the chitosan solution was adjusted to 6.5 with 0.1 M HCl to obtain an acidified chitosan solution; HRP (0.2 mg / mL) and H2O2 (1 mM) were added and stirred for 30 min, and aniline (0.1 M) was added. The mass concentration and molar concentration here were set according to the volume of the final mixed solution. The oxidative polymerization reaction was carried out by stirring at room temperature for 24 h. Among them, the acidified chitosan was used as a template, and the aniline underwent in situ polymerization to form polyaniline, which formed a composite conductive polymer with the acidified chitosan. Since the reaction was carried out in a weak acid environment containing proton acid, the polyaniline also underwent proton acid doping modification. The reaction finally obtained a sol containing a chitosan-based conductive polymer (composite conductive material).

[0085] S3: The molybdenum disulfide nanosheets prepared in step S1 are added to the sol prepared in step S2 and stirred for 30 minutes to allow hydrogen bonding, electrostatic adsorption, and π-π bonding reactions to fully react with the composite conductive polymer to form a composite system. Finally, the mixture is dried at 80°C for 12 hours to form a powder, thereby obtaining a MoS2 / chitosan-based conductive polymer composite material, i.e., a thermoelectric composite material. The mass ratio of molybdenum disulfide in the thermoelectric composite material is approximately 20%.

[0086] Example A2

[0087] This embodiment provides a thermoelectric composite material and a preparation method thereof. The preparation method differs from that of Example A1 in that aniline is replaced with pyrrole in step S2, and the other steps are the same.

[0088] Example A3

[0089] This embodiment provides a thermoelectric composite material and a preparation method thereof. The preparation method differs from that of Example A1 in that in step S1, MoCl5 is replaced with sodium tungstate (Na2WO4·2H2O), a small amount of ammonia is added before hydrothermal reduction, the pH value of the reaction solution is adjusted to 9, and the hydrothermal reduction temperature is changed to 200°C. The 2D TMDs prepared are tungsten disulfide, and the other steps are the same.

[0090] Example A4

[0091] This embodiment provides a thermoelectric composite material and a preparation method thereof. The preparation method differs from that of Example A1 in that thiourea is replaced with selenourea in step S1, a small amount of ammonia is added before hydrothermal reduction, the pH value of the reaction solution is adjusted to 9, and the temperature of the hydrothermal reduction is changed to 210°C. The 2D TMDs obtained are molybdenum diselenide, and the other steps are the same.

[0092] Comparative Example A1

[0093] This comparative example provides a thermoelectric composite material and a preparation method thereof. The preparation method differs from Example A1 only in that commercial two-dimensional layered bismuth telluride (Bi2Te3) nanosheets are purchased and the molybdenum disulfide in Example A1 is replaced with the bismuth telluride nanosheets. The other steps are the same to prepare the corresponding thermoelectric composite material.

[0094] Comparative Example A2

[0095] This comparative example provides a thermoelectric composite material and a preparation method thereof. The preparation method differs from Example A2 only in that commercial two-dimensional layered lead telluride (PbTe) nanosheets are purchased and the molybdenum disulfide in Example A2 is replaced with the lead telluride nanosheets. The other steps are the same to prepare the corresponding thermoelectric composite material.

[0096] Example B1

[0097] This embodiment provides a thermoelectric building material additive and a thermoelectric cement-based material, and the preparation method includes the following steps G1 to G3:

[0098] G1: Activate waste concrete to prepare carrier

[0099] The collected waste concrete was first crushed into particles with a particle size of 0 to 1 mm using a crusher, and then sent to a screening device to screen out fine powder with a Dv50 particle size of ≤0.5 mm. The powder was then immersed in a dilute hydrochloric acid solution to remove chemical impurities in the waste concrete. At the same time, the surface of the waste concrete fine powder was acid-activated to promote surface porosity. Finally, the filter residue was filtered and heated to 300°C at a heating rate of 10°C / h under a nitrogen atmosphere and dried for 24 hours to obtain activated concrete powder, i.e., an inorganic silica gel carrier.

[0100] G2: Preparation of thermoelectric building material additives

[0101] Water and ethanol were prepared into a 100 mL mixed solvent at a volume ratio of 4:1, and 5 g of the activated concrete powder from step G1 was dispersed in the mixed solvent. The thermoelectric composite material from Example A1 was then added to the mixed solvent at a ratio of 2 mg / mL, i.e., 0.2 g. The mixture was stirred at 500 rpm for 30 min, and then ultrasonic dispersion treatment was performed with a power of 200 W, a frequency of 40 kHz, and a time of 30 min. After completion, the mixture was allowed to stand for 10 min, and finally low-temperature drying was performed at 80°C for 12 h to obtain MoS2 / chitosan conductive polymer modified concrete powder, i.e., a thermoelectric building material additive. The mass ratio of the thermoelectric composite material in the thermoelectric building material additive was 3.85%.

[0102] G3: Preparation of thermoelectric cement-based materials

[0103] The thermoelectric building material additive was designed by replacing the Portland cement with a 10% mass fraction of the Portland cement: sand: water ratio of 1:3:0.35. The cement, thermoelectric building material additive, standard sand, water, and a water reducer were then accurately weighed, with the water reducer accounting for 1% of the total cementitious materials. Following standard procedures, the powders were thoroughly mixed, and then standard sand, water, and water reducer were added to form a slurry, resulting in the thermoelectric cement-based material. Finally, 40×40×160 mm cement mortar specimens were cast and cured under standard conditions of 20±2°C, 95% RH, and 28 days. After drying and solidification, the surface was further polished to ensure that the upper and lower end faces were flat and parallel, resulting in the finished product.

[0104] Example B2

[0105] This embodiment provides a thermoelectric building material additive and a thermoelectric cement-based material. The preparation method differs from that of Example B1 only in that, in step G2, the thermoelectric composite material in Example A1 is added to the mixed solvent at a ratio of 2 mg / mL, but is added to the mixed solution at a ratio of 3 mg / mL, thereby increasing the mass ratio of the thermoelectric composite material in the thermoelectric building material additive from 3.85% to 5.66%. The other steps are the same.

[0106] Example B3

[0107] This embodiment provides a thermoelectric building material additive and a thermoelectric cement-based material. The preparation method differs from that of Example B1 only in that, in step G2, the thermoelectric composite material in Example A1 is added to the mixed solvent at a ratio of 2 mg / mL, but is added to the mixed solution at a ratio of 4 mg / mL, thereby increasing the mass ratio of the thermoelectric composite material in the thermoelectric building material additive from 3.85% to 7.41%. The other steps are the same.

[0108] Example B4

[0109] This embodiment provides a thermoelectric building material additive and a thermoelectric cement-based material. The preparation method differs from that of Example B1 only in that, in step G2, the thermoelectric composite material in Example A1 is added to the mixed solvent at a ratio of 2 mg / mL, but is added to the mixed solution at a ratio of 5 mg / mL, thereby increasing the mass ratio of the thermoelectric composite material in the thermoelectric building material additive from 3.85% to 9.09%. The other steps are the same.

[0110] Example B5

[0111] This embodiment provides a thermoelectric building material additive and a thermoelectric cement-based material. The preparation method differs from that of Example B1 only in that, in step G3, the thermoelectric building material additive is designed to replace the silicate cement therein with a mass fraction of 10% instead of 15%. The other steps are the same.

[0112] Example B6

[0113] This embodiment provides a thermoelectric building material additive and a thermoelectric cement-based material. The preparation method differs from that of Example B1 only in that, in step G3, the thermoelectric building material additive is designed to replace the silicate cement therein with a mass fraction of 10% instead of 20%. The other steps are the same.

[0114] Comparative Example B1

[0115] This comparative example provides a thermoelectric building material additive and a thermoelectric cement-based material. The preparation method differs from that of Example B1 only in that the thermoelectric composite material in step G2 of Example B1 is replaced with the thermoelectric composite material containing bismuth telluride in Comparative Example A1, and the other steps are the same.

[0116] Comparative Example B2

[0117] This comparative example provides a thermoelectric building material additive and a thermoelectric cement-based material. The preparation method differs from that of Example B1 only in that the thermoelectric composite material in step G2 of Example B1 is replaced with the thermoelectric composite material containing lead telluride in Comparative Example A2, and the other steps are the same.

[0118] Comparative Example B3

[0119] This comparative example provides a cement-based material. The preparation method differs from that of Example B1 only in that it is a blank experiment in the control group, and in step G3, no thermoelectric building material additive is added.

[0120] The differences between Examples B1 to B6 and Comparative Examples B1 to B2 are shown in Table 1.

[0121]

[0122] Related performance tests and result analysis

[0123] The mechanical properties and thermoelectric conversion performance of the parts prepared in Examples B1 to B6 and Comparative Examples B1 to B3 were tested, and the results are recorded in Table 2:

[0124] 1. Mechanical properties test

[0125] 1. Instrument:

[0126] Microcomputer controlled compression testing machine.

[0127] 2. Test steps:

[0128] (1) Flexural strength: According to GB / T 17671-2021 Test method for strength of cement mortar, a three-point bending test was performed after 28 days of curing, and the average value was taken;

[0129] (2) Compressive strength: Take 6 broken specimens for compressive test and take the average value.

[0130] 2. Thermoelectric conversion performance test

[0131] Prepare 40 × 40 × 10 mm pressed specimens using the same mix ratio as for the mechanical test and subject them to standard curing (20 ± 2°C, 95% RH, 28 days). After drying, polish the surface to ensure that the upper and lower end surfaces are flat and parallel.

[0132] 1. Instrument:

[0133] Seebeck coefficient: SBA 458 Nemesis (steady-state temperature difference method);

[0134] Conductivity: RTS-9 four-probe tester;

[0135] Thermal conductivity: LFA 467 HyperFlash (Laser Flash).

[0136] 2. Test steps:

[0137] (1) Seebeck coefficient (S) test:

[0138] Steady-state method: a temperature difference of ΔT = 10 K is applied between the upper and lower surfaces of the specimen (hot end 305 K, cold end 295 K);

[0139] Record the thermoelectric potential ΔV and calculate S = -ΔV / ΔT

[0140] (Repeat 3 times and take the average)

[0141] (2) Conductivity (σ) test:

[0142] Four-probe method: probe spacing 2 mm, constant current source input I = 10 mA, measure voltage drop ΔV;

[0143] Calculate σ = (I·L) / (ΔV·A)

[0144] Where, L is the probe distance, and A is the cross-sectional area.

[0145] (3) Thermal conductivity (κ) test:

[0146] Laser flash method: pulsed laser irradiates the lower surface of the specimen, and the infrared detector records the temperature rise curve of the upper surface;

[0147] Calculate the thermal diffusivity α, combine the specific heat Cp (measured by DSC) and the density ρ, and obtain κ = α·Cp·ρ. The results are shown in Table 2. In Table 2, S is the Seebeck coefficient in μV / K, σ is the electrical conductivity in S / m, κ is the thermal conductivity in W / m·K, and ZT is the thermoelectric figure of merit:

[0148]

[0149] It can be seen from the data in Table 2 that the thermoelectric cement-based materials obtained by replacing cement with an appropriate amount of thermoelectric building material additives (10% to 20% replacement rate) can improve the mechanical properties of the obtained parts. With the increase of the dosage of thermoelectric building material additives, the thermoelectric performance of the parts made of thermoelectric cement-based materials is significantly enhanced; when the dosage is 15%, the ZT value is optimal and meets the low energy recovery scenario; taking into account both conductivity and thermal insulation, the performance begins to gradually decline when it is further increased to 20%.

[0150] The table also notes that the Seebeck coefficient of thermoelectric cement-based materials is positive. This is because cement-based materials are generally alkaline environments, especially during hydration reactions, which are highly alkaline environments with a pH even higher than 12. This has a reconstructive effect on the type of semiconductor carriers in the thermoelectric composite materials. Although 2D TMDs are N-type semiconductors, the Seebeck coefficient of the overall thermoelectric composite material obtained after synergistic enhancement is negative. However, after being loaded by inorganic silica gel carriers and embedded in the cement matrix, the high alkaline environment significantly changes the carrier transport mechanism: on the one hand, the alkaline conditions promote the deprotonation reaction of P-type semiconductor polymers (such as polyaniline), causing their highest occupied molecular orbital (HOMO) energy level to shift upward, significantly improving the hole concentration and mobility; on the other hand, the Ca in the cement matrix 2+ OH -The binding of the conductive polymer with surface defects in the 2D TMDs inhibits electron conduction pathways, while the composite conductive polymer forms a continuous hole transport network in an alkaline environment. This environmentally induced P-type dominance effect reverses the system's charge carrier type from electron-dominated (N-type) to hole-dominated (P-type), resulting in a positive Seebeck coefficient. The table also shows that existing technologies often struggle to adapt to these environmentally induced effects, while the thermoelectric cement-based materials produced from the thermoelectric composite materials of the present application examples still exhibit excellent performance.

[0151] The thermoelectric composite materials prepared in Examples A1 to A4 and Comparative Examples A1 to A2 were tested for thermoelectric conversion performance. The results are recorded in Table 3. In Table 3, S is the Seebeck coefficient, in μV / K. Since these nanosheets are all N-type semiconductors, and the P-type semiconductor polymer acts synergistically with them, the formed thermoelectric composite material is more negative, so the Seebeck coefficient is negative. σ is the electrical conductivity, in S / m, κ is the thermal conductivity, in W / m·K, and ZT is the thermoelectric figure of merit:

[0152]

[0153] As can be seen from Table 3, Example A1 (MoS2 / polyaniline / chitosan system) is the optimal solution with an absolute advantage of a ZT value of 0.21. The core of this is the high electron mobility of MoS2 (final σ = 35 S / m), the proton acid doping of polyaniline to enhance carrier transport, and the blocking effect of the chitosan molecular chain on the phonon path (final κ = 0.45 W / m·K). These three factors work together to achieve the difficult goal of high electrical conductivity and low thermal conductivity of thermoelectric materials.

[0154] Example A2 uses polypyrrole as the P-type semiconductor polymer, and its performance is slightly worse, with a final ZT of 0.12; Example A3 mainly results in a ZT of 0.08 due to insufficient electron mobility of WS2; Example A4 has a higher Seebeck coefficient (-105 µV / K) but a lower conductivity (18 S / m), which limits the ZT value (0.11), but the overall thermoelectric figures of merit of the examples are higher than those of the comparative examples.

[0155] Although the bismuth telluride in Comparative Example A1 also has a layered structure, it is not a transition metal dichalcogenide and its overall performance is significantly inferior to that of transition metal dichalcogenides. In addition, the Bi2Te3 surface is easily oxidized, causing κ to increase dramatically to 1.45 W / m·K, affecting the thermoelectric figure of merit. The lead telluride in Comparative Example A2 also has corresponding problems, and lead ions are highly hazardous, making it less green and sustainable than the embodiment solution.

[0156] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A thermoelectric cement-based material, characterized in that: It includes cement and thermoelectric building material additives, wherein the thermoelectric building material additives include thermoelectric composite materials and inorganic silica gel, and the thermoelectric composite materials are combined on the inorganic silica gel carrier; The thermoelectric composite material comprises a two-dimensional transition metal disulfide compound, a P-type semiconductor polymer, and a conductive polymer, wherein the P-type semiconductor polymer and the conductive polymer are cross-linked to form a composite conductive polymer, and the two-dimensional transition metal disulfide compound is dispersed in the composite conductive polymer; The two-dimensional transition metal dichalcogenide compound includes at least one of molybdenum disulfide, tungsten disulfide, molybdenum diselenide, and molybdenum ditelluride; The P-type semiconductor polymer includes at least one of polyaniline, polythiophene, and polypyrrole; The conductive polymer comprises at least one of acidified chitosan, lignin-based composite conductive polymer, and poly (3,4-ethylenedioxythiophene): polystyrene sulfonate.

2. The thermoelectric cement-based material according to claim 1, characterized in that: The mass percentage of the two-dimensional transition metal dichalcogenide compound in the thermoelectric composite material is 15% to 25%; And / or, the mass percentage of the P-type semiconductor polymer in the thermoelectric composite material is 10% to 15%; And / or, the conductive polymer has a mass percentage of 60% to 75% in the thermoelectric composite material.

3. The thermoelectric cement-based material according to claim 1 or 2, characterized in that: The two-dimensional transition metal dichalcogenide compound comprises molybdenum disulfide, the P-type semiconductor polymer comprises polyaniline, and the conductive polymer comprises acidified chitosan; And / or, the two-dimensional transition metal dichalcogenide compound includes molybdenum disulfide, and the molybdenum disulfide includes at least one of the following characteristics (1) to (3): (1) The number of layers is 2 to 5; (2) interlayer spacing of 0.615 nm; (3) The crystal form includes at least one of 2H, 1T, and 1T'.

4. The thermoelectric cement-based material according to claim 1 or 2, characterized in that: The preparation method of the thermoelectric composite material comprises the following steps: The raw materials including the two-dimensional transition metal dichalcogenide compound and the composite conductive polymer are subjected to a first mixing process to obtain a thermoelectric composite material.

5. The thermoelectric cement-based material according to claim 1 or 2, characterized in that: The preparation method of the two-dimensional transition metal dichalcogenide compound includes a hydrothermal reduction method; And / or, the preparation method of the composite conductive polymer comprises the following steps: The conductive polymer is used as a template to carry out an oxidative polymerization reaction on the monomer of the P-type semiconductor polymer to obtain the composite conductive polymer.

6. The thermoelectric cement-based material according to claim 1 or 2, characterized in that: The inorganic silica gel carrier includes at least one of acid-activated waste concrete and dry silicic acid gel; And / or, the mass percentage of the thermoelectric composite material in the thermoelectric building material additive is 5% to 8%.

7. The thermoelectric cement-based material according to claim 1 or 2, characterized in that: The preparation method of the thermoelectric building material additive comprises the following steps: The thermoelectric composite material and the inorganic silica gel carrier are subjected to a second mixing process.

8. The thermoelectric cement-based material according to claim 1 or 2, characterized in that: The composition comprises the following components in parts by weight: 0.1 to 0.2 parts of the thermoelectric building material additive; 0.8 to 0.9 parts of the cement; 3 parts sand; 0.33-0.36 parts of water; Water reducing agent 0.009-0.012 parts.

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