A hollow copper selenide box, its preparation method and application

Abstract

The present invention provides a hollow copper selenide box, a preparation method thereof and an application thereof, belonging to the field of wireless communication technology. The present invention uses a Cu2O cube as a sacrificial template, and through a template-directed in-situ selenization reaction, the Cu2O microcube is successfully converted into Cu 2‑x Se microcube box at room temperature by a wet chemical method. The present invention realizes the construction of a self-supporting microcube-structured hollow Cu 2‑x Se heteroselenium copper box under the synergistic effect of the Kirkendall effect and the Ostwald ripening effect, and has rare low-frequency electromagnetic wave absorption performance. The composite product of the hollow copper selenide box prepared by the present invention and paraffin has good low-frequency electromagnetic wave absorption characteristics (from 4 GHz) when the filling amount is 40 wt%, and the minimum RL value of T5 / paraffin-40 wt% exceeds -20 dB at 2.6 mm - 5.0 mm.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technologies, and in particular, to a hollow copper selenide box, a preparation method thereof, and an application thereof. Background Art

[0002] In wireless communication and military applications, the rapid development of 5G electronic devices has prompted researchers to develop electromagnetic wave absorbing materials in the GHz frequency range. However, due to its limited EMW (electromagnetic wave) attenuation mechanism, there are still challenges. To this end, continuous efforts have been made to improve its electromagnetic response ability and optimize impedance matching, including the careful design of parameters such as morphology, defect level, electronic conductivity, composition characteristics, and interface structure.

[0003] Copper selenide is a p-type semiconductor with high terrestrial abundance. Due to their complex structures and valence states (such as Cu 0.87 Se, CuSe, Cu 3 Se 2 、Cu 1.8 Se, Cu 2 Se, CuSe 2 etc.), some unique optical and electrical properties are caused, which makes it widely used in many fields such as sensors, solar cells, electronic switches, etc. Moreover, a large amount of work has been invested in synthesizing copper selenide crystals with different morphologies such as nanoparticles, nanowires, and nanotubes. Therefore, it is still of great significance to study new copper selenide absorbing materials and improve the electromagnetic wave absorption performance of copper selenide. Summary of the Invention

[0004] The purpose of the present invention is to provide a hollow copper selenide box, a preparation method thereof, and an application thereof. The hollow copper selenide box has excellent electromagnetic wave absorption performance and good low-frequency absorption characteristics.

[0005] To achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a preparation method of a hollow copper selenide box, including the following steps:

[0007] Mix copper salt, alkali, glucose, and water, and perform reduction to obtain Cu 2 O cubic powder;

[0008] Mix Se powder and alkali solution, and perform a hydrothermal reaction to obtain a Se ion-containing solution;

[0009] Mix the Cu 2 O cubic powder and water, mix the obtained suspension with the Se ion-containing solution, and perform a selenization reaction to obtain a hollow copper selenide box.

[0010] Preferably, the copper salt includes copper sulfate and the base includes sodium hydroxide.

[0011] Preferably, the mass ratio of the copper salt, the base and glucose is 7.5:3.6:4.2.

[0012] Preferably, the reduction temperature is 70 °C and the time is 30 min.

[0013] Preferably, the dosage ratio of Se powder to the alkali solution is 12.66 mmol:50 mL; the concentration of the alkali solution is 2.5 - 10 mol / L.

[0014] Preferably, the hydrothermal reaction temperature is 120 °C and the time is 4 h.

[0015] Preferably, the 2 molar ratio of the Cu

[0016] O cube powder to Se powder is 3.47:12.66.

[0017] The present invention provides a hollow copper selenide box prepared by the preparation method described in the above technical solution, presenting a hollow cubic structure.

[0018] The present invention provides the application of the hollow copper selenide box described in the above technical solution in the field of electromagnetic wave absorption.

[0019] The present invention provides a preparation method of a hollow copper selenide box. The present invention uses a Cu 2 O cube as a sacrificial template. Through template-directed in-situ selenization reaction, Cu 2 O microcubes are successfully converted into Cu 2-x Se microcube boxes at room temperature by a wet chemical method. The present invention realizes the construction of a self-supporting microcubic structure of hollow Cu 2-x Se heterocopper selenide boxes under the synergistic action of the Kirkendall effect and the Ostwald ripening effect, having rare low-frequency electromagnetic wave absorption performance.

[0020] In addition, the hollow structure in the copper selenide box prepared by the present invention solves the problem of large density of conventional copper selenide. The density reduction enables the hollow powder to have a higher filling volume than the conventional powder under the same filling mass in the matrix. The increase in filling volume has a certain gain on the dielectric constant (particles come into contact with each other to form a conductive network). Therefore, the wave-absorbing material can function at a lower filling mass of the wave-absorbing agent. Moreover, the material with a hollow structure provides an effective idea for the manufacture of lightweight and efficient EMW absorbers due to its good impedance matching, high loss and adjustable electromagnetic parameters.

[0021] The hollow Cu 2-xThe composite product of copper selenide box and paraffin has excellent electromagnetic wave absorption characteristics, and has good low-frequency absorption characteristics of EMW (electromagnetic wave) (starting from 4 GHz) when the filling amount is 40 wt%. The minimum RL value of T5 / paraffin-40 wt% exceeds -20 dB from 2.6 mm to 5.0 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 XRD (a), SEM (b) and particle size distribution diagram (c) of the Cu 2 O cube powder prepared by the present invention;

[0023] Figure 2 For Cu 2 XRD patterns (a) of the Cu 2-x O cube template undergoing different seleniumization times (T1-T5) from 15 min to 5 h and standard diffraction patterns (b) of three kinds of Cu

[0024] Figure 3 For Cu 2 TEM images of each stage of Cu

[0025] Figure 4 XRD patterns (a) of Cu 2-x Se (N1-N3) prepared under different NaOH concentrations and standard diffraction spectra (b) of CuO, Cu 3 Se 2 and Cu 0.87 Se;

[0026] Figure 5 For Cu 2 TEM images of the seleniumization products (N1-N3) of Cu

[0027] Figure 6 Curves of ε′ and ε″ of T5 / paraffin with different filling ratios varying with frequency (a-b), dielectric loss (c) and Cole-Cole curves (d-f);

[0028] Figure 7 For R L Variation diagrams (a-c) of T5 / paraffin-30 wt%, T5 / paraffin-40 wt%, T5 / paraffin-50 wt% at 2-18 GHz and two-dimensional R L of T5 / paraffin-40 wt% (d). DETAILED DESCRIPTION OF THE INVENTION

[0029] The present invention provides a method for preparing a hollow copper selenide box, comprising the following steps:

[0030] Mix copper salt, alkali, glucose and water, and perform reduction to obtain Cu 2 O cube powder;

[0031] Mix Se powder and alkali solution, and perform hydrothermal reaction to obtain a solution containing Se ions;

[0032] Mix the Cu 2 O cube powder and water, mix the resulting suspension with the solution containing Se ions, and perform selenization reaction to obtain hollow copper selenide boxes.

[0033] In the present invention, unless otherwise specified, the required reagents are all well-known commercially available products in the art.

[0034] In the present invention, copper salt, alkali, glucose and water are mixed, and reduction is performed to obtain Cu 2 O cube powder.

[0035] In the present invention, the copper salt preferably includes copper sulfate, and more preferably copper sulfate pentahydrate; the alkali preferably includes sodium hydroxide.

[0036] In the present invention, the mass ratio of the copper salt, alkali to glucose is preferably 7.5:3.6:4.2.

[0037] In the present invention, it is preferred to dissolve the copper salt in part of the water, under the set reduction temperature condition, completely dissolve the copper salt by stirring, dissolve the alkali in the remaining water, add the resulting alkali solution to the copper salt solution, continuously stir for 5 min and then add glucose for reduction.

[0038] In the present invention, the temperature of the reduction is preferably 70 °C, and the time is preferably 30 min; the reduction is preferably performed under stirring conditions.

[0039] After completing the reduction, in the present invention, it is preferred to collect the resulting product by centrifugation, filter the excess liquid, wash the product with deionized water, and dry it in vacuum at 50 °C for 12 h to obtain Cu 2 O cube powder.

[0040] In the present invention, Se powder and alkali solution are mixed, and hydrothermal reaction is performed to obtain a solution containing Se ions. In the present invention, the dosage ratio of the Se powder to the alkali solution is preferably 12.66 mmol:50 mL; the concentration of the alkali solution is preferably 2.5 - 10 mol / L, and more preferably 5 - 7.5 mol / L; the alkali in the alkali solution is preferably sodium hydroxide.

[0041] The present invention has no special limitation on the process of mixing the Se powder and the alkali solution, and the materials can be mixed evenly according to the process well-known in the art.

[0042] In the present invention, the temperature of the hydrothermal reaction is preferably 120 °C, and the time is preferably 4 h; during the hydrothermal reaction, Se reacts with the alkali solution to form Se 2- , and Se is transformed into 2 / 3Na 2 Se and 1 / 3Na 2 SeO 3 .

[0043] After completing the hydrothermal reaction, in the present invention, it is preferred to naturally cool the obtained system to room temperature, filter and separate the excess Se powder, and collect the liquid material, which is an alkaline Se-containing ionic solution (containing Na 2 Se and Na 2 SeO 3 ).

[0044] After obtaining the Se-containing ionic solution, in the present invention, the Cu 2 O cubic powder and water are mixed, and the obtained suspension is mixed with the Se-containing ionic solution to carry out a selenization reaction to obtain hollow copper selenide boxes.

[0045] The present invention has no special limitation on the dosage ratio of the Cu 2 O cubic powder and water, as long as the Cu 2 O cubic powder can be fully dispersed and suspended; in the examples of the present invention, specifically, 3.47 mmol of Cu 2 O cubic powder is stirred and dispersed in 400 mL of deionized water.

[0046] In the present invention, the molar ratio of the Cu 2 O cubic powder to the Se powder is preferably 3.47:12.66.

[0047] In the present invention, the temperature of the selenization reaction is preferably room temperature, and the time is preferably 3 - 5 h; the selenization reaction is preferably carried out under stirring conditions; the present invention has no special limitation on the stirring, and the reaction can be ensured to proceed smoothly according to the process well-known in the art. During the selenization reaction, the Cu 2 O cube acts as a sacrificial template, and Na 2 Se in the Se-containing ionic solution plays the role of selenizing Cu 2 O to form copper selenide.

[0048] After completing the selenization reaction, in the present invention, it is preferred to collect the product by suction filtration, then wash it with deionized water, and then vacuum dry the obtained product to obtain hollow copper selenide boxes. The present invention has no special limitation on the suction filtration and vacuum drying, and it can be carried out according to the process well-known in the art.

[0049] The present invention provides hollow copper selenide boxes prepared by the preparation method described in the above technical solution, which present a hollow cubic structure.

[0050] The present invention provides an application of the hollow copper selenide box described in the above technical solution in the field of electromagnetic wave absorption. The present invention has no special limitation on the method of the application, and it can be applied according to the methods well-known in the art.

[0051] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0052] Examples 1-8

[0053] Table 1 Raw material dosages and selenization times of different cases

[0054]

[0055] Dissolve 7.5 g of CuSO 4 ·5H 2 O in 300 mL of deionized water, and completely dissolve it under stirring at 70 °C. Subsequently, add 30 mL of the prepared NaOH solution (containing 3.6 g of NaOH), continue stirring for 5 min, then add 4.2 g of glucose, and react for another 30 min. Collect the product by centrifugation, filter the excess liquid, wash the product with deionized water, and then vacuum dry it at 50 °C for 12 h to obtain Cu 2 O cubic powder;

[0056] Dissolve Se powder (dosage shown in Table 1) in 50 mL of NaOH solution (concentration shown in Table 1), keep it at 120 °C for 4 h, naturally cool it to room temperature, filter and separate the excess Se powder, and collect the alkaline selenium ion-containing aqueous solution;

[0057] Take 3.47 mmol of the prepared Cu 2 O cubic powder and place it in 400 mL of deionized water to obtain a Cu 2 O suspension. Under continuous stirring, add the above selenium ion-containing aqueous solution to the obtained Cu 2 O suspension, and carry out selenization at room temperature (selenization time shown in Table 1). Filter and collect the product, wash it with deionized water, and vacuum dry the obtained product to obtain the hollow copper selenide box.

[0058] Characterization and performance testing

[0059] 1) The surface and internal morphology of the samples prepared in different examples were observed using a scanning electron microscope (SEM, ZEISS sigma500) and a transmission electron microscope (TEM, FEI-Tecnai G2 F20). The phase and composition of the samples were analyzed using X-ray powder diffraction (XRD, UltimalV, Cu / Kα), TEM-SEAD mode, and EDS-Mapping energy spectrum (BRUKER XFlash 6130).

[0060] Figure 1 Cu prepared according to the present invention 2 XRD (a), SEM (b), and particle size distribution diagram (c) of the O cube powder, as Figure 1 shown. The prepared Cu 2 O cube is in complete agreement with the Cu 2 O crystal standard card PDF#74-1230 (a). The prepared Cu 2 O cube particles have uniform size, smooth surface, and good dispersion (b). The size-frequency distribution of the Cu 2 O cube shows a normal distribution, and its average particle size is about 1 μm (c).

[0061] Figure 2 In (a), it is the XRD pattern of the Cu 2 O cube template undergoing different selenization times (T1-T5) from 15 min to 5 h. The solid dots therein correspond to the diffraction peaks of Cu 2 O. It can be clearly seen that as the selenization time prolongs, the diffraction peak representing the Cu 2 O {111} plane at 36.46° gradually disappears, indicating that the product gradually transforms from Cu 2 O to Cu 2-x Se. Figure 2 In (b), it is the standard diffraction patterns of three kinds of Cu 2-x Se, including two kinds of CuSe (20-1020, hexagonal and 27-0184, orthorhombic) and Cu 0.87 Se. It can be seen that when the reaction time is within the first 30 min, the main phase of Cu 2-x Se in the complex is the hexagonal type of CuSe. When the reaction time is 1 h, the orthorhombic phase of CuSe appears briefly. After that, as the reaction proceeds, the CuSe in Cu 2-x Se is finally replaced by Cu 0.87 Se (3 h and 5 h), which may be due to the slightly excessive Se 2- ions in the system. After comparison with the standard diffraction spectra, the main components of T4 and T5 are Cu 0.87 Se.

[0062] Figure 3 is Cu 2 TEM images of Cu Figure 3 O at various stages during the selenization process, where (a) represents a selenization time of 15 min, (b) represents a selenization time of 30 min, (c) represents a selenization time of 1 h, (d) represents a selenization time of 3 h, and (e) represents a selenization time of 5 h; as 2 shown, the morphology of the product varies significantly at different stages. In the first 30 min, the cubic morphology can be well inherited, but the surface gradually becomes rough and wrinkled, indicating that the surface of the Cu 2-x O cube is transformed into Cu 2-x Se (a - b). When the selenization time increases to 1 h, Cu 2 Se gradually increases and begins to detach from the surface of Cu 2 O, exposing the spherical Cu 2 O core (c). Until 3 h, the internal Cu 2-x O is almost completely consumed, and the free Cu 2-x Se around forms tortuous nanosheets and aggregates and connects with each other, and the prototype of a hollow cube can be observed (d). When the reaction proceeds to 5 h, Cu 2 Se hollow boxes are produced. The walls of the boxes are composed of coarse grains, the surface is rough, and there are voids inside. It is similar in shape to the original Cu 0.87 O cube, but the size is significantly increased (e). f is the high-resolution TEM pattern of T5. The result of measuring the interplanar spacing in the lattice fringes is 0.32 nm, corresponding to the {102} crystal plane of Cu 0.87 Se (the diffraction peak located at 28.1° in the XRD pattern). However, the inset SEAD electron diffraction in f simultaneously shows single-crystal diffraction spots and polycrystalline diffraction rings, indicating that T5 is not pure Cu 2-x Se, and there may be other varieties of Cu

[0063] In summary, the copper selenide box of the present invention is prepared by the combined action of the Kirkendall effect and the Ostwald ripening effect: Since the solubility of Cu 2-x Se in an alkaline aqueous solution is much lower than that of Cu 2 O, it can be formed by contacting Se 2- ions with Cu 2 O through the dissolution process. At the same time, during the transformation process, the change in the valence of Cu + ions also causes a redox reaction. At this time, the Cu 2 O particles maintain a cubic morphology, and only a thin layer of Cu 2-x Se film is formed on the surface. This film is composed of many small Cu 2-x composed of Se grains. Subsequently, under the action of the Kirkendall effect, Cu 2 in Cu + ions migrate from the inside to the outside and continue to react with the external Se 2- ions. At this time, Cu 2-x Se grains detach from Cu 2 O and grow and thicken into a shell during the Ostwald ripening process until Cu 2 O is completely depleted, and the surrounding Cu 2-x Se aggregates into an incomplete hollow cube prototype. Finally, during the Ostwald ripening process, in order to maintain the lowest energy of the system, smaller Cu 2-x Se fragments will gradually dissolve and precipitate again on the surface of larger grains. This grain coarsening process thickens the Cu 2-x Se shell and finally develops into a hollow cube with a complete morphology.

[0064] Based on the Cu 2 O template, the formation of Cu 2-x Se hollow boxes can be attributed to chemical reaction formulas (1) and (2):

[0065] 3Se + 6NaOH → 2Na 2 Se + Na 2 SeO 3 + 3H 2 O (1)

[0066] 2Cu 2 O + 4Na 2 Se + 4H 2 O + O 2 → 4CuSe + 8NaOH (2).

[0067] 2) The acquisition of Se 2- is achieved through the disproportionation reaction of Se powder in an alkaline solution, indicating that the alkaline solution plays an important role in the acquisition of Se 2- . The present invention studies the influence law of different NaOH concentrations on the morphology of Cu 2-x Se.

[0068] Figure 4 In (a), the XRD patterns of Cu 2-x Se (N1 - N3) prepared at different NaOH concentrations are shown. The solid dot markers represent the characteristic diffraction peaks of Cu 2 O. Similar to (a) in Figure 1 , as the NaOH concentration increases, the characteristic diffraction peaks of Cu 2 O gradually disappear, and the product is completely converted into Cu 2-x Se. Figure 4In (b), it is CuO and Cu 3 Se 2 and Cu 0.87 Se's standard diffraction pattern. It can be seen that when the NaOH concentration is 2.5 M, the product consists of Cu 2 O, CuO, and Cu 3 Se 2 coexisting in three phases. Since oxygen 2 participates in the selenization process, the valence state of Cu + ions increases. Therefore, CuO may be the intermediate product of the selenization reaction of Cu 2 O. When the NaOH concentration is above 5.0 M, the characteristic diffraction peaks of Cu 2 O and CuO become weaker until they disappear. At the same time, the diffraction peak at 26.9° gradually becomes stronger (corresponding to Cu 0.87 Se). Until 7.5 M, there is no copper oxide in the product, and Cu 2-x Se is composed of Cu 3 Se 2 and Cu 0.87 Se. In fact, when the NaOH concentration is below 10 M, there is excess Se powder that can be filtered, indicating that Se→Se 2- cannot be fully converted. Therefore, when the NaOH concentration is low, there is not only residual copper oxide in the product, but also the proportion of Cu element in Cu 2-x Se is generally higher.

[0069] Figure 5 are the TEM images of the selenization products (N1 - N3) of Cu 2 O cubic powder at different NaOH concentrations. Among them, (a) represents a NaOH concentration of 2.5 M, (b) represents a NaOH concentration of 5 M, and (c) represents a NaOH concentration of 7.5 M; as Figure 5 shown, when the NaOH concentration is below 5 M, it can be observed that as the NaOH concentration increases, Cu 2-x Se fragments gradually aggregate into the prototype of Cu 2-x Se boxes (a - b). Until the NaOH concentration reaches 7.5 M, Cu 2-x Se develops into a complete hollow box (c). However, compared with T5 (NaOH concentration of 10 M), the wall of this Cu 2-x Se box is thinner, which is due to the slightly lower concentration of Se 2- ions. The above experiments confirm the existence of the Kirkendall effect and the Ostwald ripening process from the side, and the speed of these reaction processes is affected by the Se 2- concentration.

[0070] 3) The complex permittivity of the samples was measured at 2 - 18 GHz using a vector network analyzer (VNA, PNA - N5234A). Among them, the sample powder was uniformly mixed with the paraffin matrix at different mass fractions, and then pressed into an annular mold with an inner diameter of 3.04 mm and an outer diameter of 7.00 mm.

[0071] Copper selenide powder (T5) was filled in the paraffin matrix at different ratios to make T5 / paraffin composites. Since copper selenide is non - magnetic, the real part (μ′) and the imaginary part (μ″) of the complex permeability can be approximately 1 and 0 respectively. In non - magnetic media, the electromagnetic wave absorption characteristics are mainly determined by the complex permittivity (ε r = ε′ - jε″). The real part ε′ represents the energy storage ability of electric energy, and the imaginary part ε″ reflects the electric loss ability.

[0072] Figure 6 In [Figure], a - b are the curves of ε′ and ε″ varying with frequency when T5 is filled at ratios of 30 wt%, 40 wt% and 50 wt% respectively. Obviously, the complex permittivity increases with the increase of the copper selenide filling ratio, and the growth is more obvious when increasing from 40 wt% to 50 wt%. When the copper selenide filling ratio is low, the copper selenide particles are isolated by the paraffin. When the filling ratio increases to a certain critical value, the copper selenide particles in the matrix will be connected to each other, thus forming a conductive path. At this time, the conductivity of the copper selenide / paraffin composite will increase greatly, thereby significantly increasing the complex permittivity. Through the dielectric loss tangent value (tanδ E = ε″ / ε′) to characterize the dielectric loss ability of T5 / paraffin with different filling ratios ( Figure 6 in [Figure] c), when the filling ratio reaches 50 wt%, the tanδ E value is above 1 in the range of 2 - 18 GHz. Although the dielectric loss ability of T5 / paraffin - 50 wt% is extremely strong, due to its too high complex permittivity, the electromagnetic wave will be strongly reflected and cannot enter the absorber smoothly, so its electromagnetic wave absorption performance is not necessarily good. In addition, from Figure 6 it is observed that the dielectric loss peaks gradually shift to lower frequencies with the increase of the filling ratio, and these loss peaks may be caused by polarization loss.

[0073] The Debye relaxation effect is described by Equation 3 below, where ε ∞ and ε s represent the permittivity at high - frequency limit and the static permittivity respectively.

[0074]

[0075] If only Debye relaxation occurs, the curves of ε′ and ε″ will form a Cole - Cole semi - circle. Figure 6In the figure, d-f represent the Cole-Cole curves of T5 / paraffin with different filling ratios. When the filling amount is 30 wt% and 40 wt%, as the frequency increases, the corresponding Cole-Cole curves rise in a spiral shape, indicating that they have multiple polarization processes. Since T5 is not only pure Cu 0.87 Se, but also includes other Cu 2-x Se varieties, so the multi-polarization process may come from the dipole polarization and interface polarization of these copper selenides. When the filling amount reaches 50 wt%, the nearly circular shape can hardly be observed, indicating that the high dielectric loss of T5 / paraffin-50 wt% is not mainly polarization relaxation loss, but is covered by high conductive loss.

[0076] The reflection loss (R L ) can be used to evaluate the absorption characteristics of electromagnetic waves (Equation 4-5):

[0077]

[0078]

[0079] Z 0 represents the normalized free space impedance (Z 0 = 1), Z in represents the input impedance, c is the speed of light, f is the EM wave frequency, d is the absorber thickness, j is the imaginary unit, and μ r is the complex magnetic permeability. The variation of R L of T5 / paraffin-30 wt% (a), T5 / paraffin-40 wt% (b), and T5 / paraffin-50 wt% (c) at 2-18 GHz is as Figure 7 shown. In the range of absorber thickness from 0 to 5 mm, the comprehensive performance of the filling mass of 40 wt% is the best. Too weak electromagnetic wave loss ability caused by low filling amount (30 wt%) and too strong electromagnetic wave reflection caused by high filling amount (50 wt%) both make the absorber unable to obtain good electromagnetic wave absorption performance. And, the absorption peaks of T5 / paraffin-40 wt% are mainly concentrated in the low-frequency range ( Figure 7 in the figure), and its minimum R L values exceed -20 dB from 2.6 mm to 5.0 mm, which is equivalent to at least being able to dissipate 99% of the electromagnetic wave energy. When the absorber thickness is 3.8 mm, the R L value reaches -35.2 dB. Many dielectric loss type electromagnetic wave absorbing materials are mainly high-frequency absorption, and the copper selenide box prepared by the present invention has rare low-frequency characteristics.

[0080] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. Application of a hollow copper selenide box in the field of electromagnetic wave absorption, characterized in that, the preparation method of the hollow copper selenide box comprises the following steps: Mix copper salt, alkali, glucose and water, and perform reduction to obtain Cu 2 O cube powder; Mix Se powder and alkali solution, carry out hydrothermal reaction to obtain a solution containing Se ions; Mix the Cu 2 O cube powder with water, mix the resulting suspension with a solution containing Se ions, and carry out a selenization reaction to obtain hollow copper selenide boxes; The mass ratio of the copper salt, alkali and glucose is 7.5:3.6:4.2; The reduction temperature is 70 °C and the time is 30 min; The dosage ratio of the Se powder to the alkali solution is 12.66 mmol:50 mL; the concentration of the alkali solution is 2.5 - 10 mol / L; The temperature of the hydrothermal reaction is 120 °C and the time is 4 h; The Cu 2 The molar ratio of the CuO cube powder to the Se powder is 3.47:12.66; The temperature of the selenization reaction is room temperature and the time is 3 - 5 h.

2. The application according to claim 1, characterized in that, the copper salt includes copper sulfate and the alkali includes sodium hydroxide.

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