A method for improving electromagnetic wave absorption performance of hollow copper selenide box

Abstract

The present invention provides a method for improving the electromagnetic wave absorption performance of hollow copper selenide boxes, belonging to the field of wireless communication technology. The present invention uses Cu2O cubes as sacrificial templates, and through template-directed in-situ selenization / sulfidation reactions, Cu2O microcubes are successfully converted into Cu 2‑x Se hollow copper selenide boxes at room temperature by a wet chemical method. Through S doping regulation engineering, the morphology, composition, heterointerfaces, defect levels, conductivity, and EMW absorption performance of the hollow copper selenide boxes are optimized. The structure, components, and complex permittivity of the hollow copper selenide boxes are regulated, and the EMW absorption performance is improved through ion substitution and the hollow cube structure. The microwave absorption characteristics are optimized from the perspectives of wide frequency band, thin thickness, and strong absorption, further improving the EMW wave absorption performance of the hollow copper selenide boxes.

Description

Technical Field

[0001] The invention relates to the technical field of wireless communications, and in particular to a method for improving the electromagnetic wave absorption performance of a hollow copper selenide box. Background Art

[0002] The rapid development of 5G electronic devices in wireless communications and military applications has prompted researchers to develop electromagnetic wave absorbing materials in the GHz frequency range. However, challenges remain due to their limited EMW (electromagnetic wave) attenuation mechanism. To this end, people continue to work hard to improve their electromagnetic response capabilities 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 earth abundance. Due to their complex structure and valence states (such as Cu 0.87 Se, CuSe, Cu 3 Se 2 , Cu 1.8 Se, Cu 2 Se, CuSe 2 etc.) lead to some unique optical and electrical properties, which make it widely used in many fields such as sensors, solar cells, electronic switches, etc., and a lot of work has been invested in the synthesis of copper selenide crystals with different morphologies such as nanoparticles, nanowires and nanotubes.

[0004] However, the electromagnetic wave absorption performance of the copper selenide materials prepared so far still needs to be further improved. Summary of the invention

[0005] The purpose of the present invention is to provide a method for improving the electromagnetic wave absorption performance of a hollow copper selenide box, which can significantly improve the electromagnetic wave absorption performance of the copper selenide box.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for improving the electromagnetic wave absorption performance of a hollow copper selenide box, comprising the following steps:

[0008] Se powder, Na 2 S is mixed with alkali solution and subjected to hydrothermal reaction to obtain a selenium-sulfur solution;

[0009] Cu 2 The O cube powder is mixed with water, and the obtained suspension is mixed with a selenium-sulfur solution to carry out a selenization-sulfurization reaction to obtain an S-doped hollow copper selenide box.

[0010] Preferably, the usage ratio of the Se powder to the alkali solution is (2.12-6.35) mmol:50 mL; and the concentration of the alkali solution is 10 mol / L.

[0011] Preferably, the temperature of the hydrothermal reaction is 120° C. and the time is 4 hours.

[0012] Preferably, the Cu 2 The preparation method of CuO cubic powder includes: mixing copper salt, alkali, glucose and water, reducing the mixture to obtain Cu 2 O cube powder.

[0013] Preferably, the copper salt includes copper sulfate, and the alkali includes sodium hydroxide; the mass ratio of the copper salt, the alkali and the glucose is 7.5:3.6:4.2.

[0014] Preferably, the reduction temperature is 70° C. and the time is 30 min.

[0015] Preferably, in the selenium-sulfur solution, S 2- with Se 2- The molar ratio is (0.2-5):1 and not 5:1.

[0016] Preferably, in the selenium-sulfur solution, S 2- with Se 2- The molar ratio is 1:5 or 3:3.

[0017] Preferably, the Cu 2 The molar ratio of O cubic powder to Se powder is 3.47:(2.12~6.35).

[0018] Preferably, the temperature of the selenization-sulfurization reaction is room temperature and the time is 5 hours.

[0019] The present invention provides a method for improving the electromagnetic wave absorption performance of a hollow copper selenide box. 2 O cubes were used as sacrificial templates and Cu was successfully synthesized by wet chemical method at room temperature through template-directed in-situ selenization / sulfurization reaction. 2 O microcubes converted to Cu 2-x Se hollow copper selenide box, through S doping adjustment engineering, optimizes the morphology, composition, heterogeneous interface, defect level, conductivity and EMW absorption performance of the hollow copper selenide box, regulates the structure, component and complex dielectric constant of the hollow copper selenide box, improves the EMW absorption performance of the hollow copper selenide box through ion substitution and hollow cube structure, optimizes the microwave absorption characteristics from the perspective of wide band, thin thickness and strong absorption, and further improves the EMW absorption performance of the hollow copper selenide box.

[0020] The results of the embodiment show that the S-doped hollow copper selenide box prepared by the method of the present invention has a high LThe strength and EAB of S1 / paraffin-40wt% have obvious advantages, and the RLmin of S2 / paraffin-40wt% is -46.3dB at 2.7mm, and the RLmin of S2 / paraffin-40wt% is -44.5dB at 1.9mm. The S doping regulation engineering mentioned in the present invention is expected to be extended to other sulfide / selenide materials and be widely used. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 XRD patterns of S-doped copper selenide boxes (S1-S3) with different sulfur contents (a) and CuSe, CuS and Cu 7 S 4 Standard diffraction spectrum of (b);

[0022] Figure 2 The middle is Cu doped with different S contents 2-x The morphology of Se boxes (S1-S3) (ac) and EDSmapping spectra of S1-S3 and the corresponding element statistics (df);

[0023] Figure 3 Specific surface area and pore size distribution diagram of S1-S3;

[0024] Figure 4 is the complex dielectric constant (ab) of T5, S1, S2 and S3 when the filling amount is 40wt% and the ε" of the composite materials of T5, S1, S2 and S3 and paraffin C and ε" P Plot of variation with frequency (cd);

[0025] Figure 5 The three-dimensional reflection loss diagram (a1, b1, c1) of S1, S2, S3 and paraffin composite materials; the two-dimensional reflection loss diagram (a2, b2, c2) of S1, S2, S3 and paraffin composite materials and the effective bandwidth / reflection loss-thickness histogram (a3, b3, c3) of S1, S2, S3 and paraffin composite materials. DETAILED DESCRIPTION

[0026] The present invention provides a method for improving the electromagnetic wave absorption performance of a hollow copper selenide box, comprising the following steps:

[0027] Se powder, Na 2 S is mixed with alkali solution and subjected to hydrothermal reaction to obtain a selenium-sulfur solution;

[0028] Cu 2 The O cube powder is mixed with water, and the obtained suspension is mixed with a selenium-sulfur solution to carry out a selenization-sulfurization reaction to obtain an S-doped hollow copper selenide box.

[0029] In the present invention, unless otherwise specified, the required reagents are commercially available products well known in the art.

[0030] The present invention uses Se powder, Na 2 S is mixed with alkali solution and subjected to hydrothermal reaction to obtain a selenium-sulfur solution.

[0031] In the present invention, the usage ratio of the Se powder to the alkali solution is preferably (2.12-6.35) mmol:50 mL, more preferably 6.35 mmol:50 mL; the concentration of the alkali solution is preferably 10 mol / L; and the alkali in the alkali solution is preferably sodium hydroxide.

[0032] In the present invention, the Na 2 S is preferably Na 2 S.9H 2 O form is used; the Na 2 The amount of S used is preferably sufficient to meet the S requirement in the selenium-sulfur solution. 2- with Se 2- The molar ratio is sufficient.

[0033] The present invention is to Se powder, Na 2 The process of mixing S with the alkali solution is not particularly limited, and the materials can be mixed uniformly according to a process well known in the art.

[0034] In the present invention, the temperature of the hydrothermal reaction is preferably 120°C, and the time is preferably 4 hours. During the hydrothermal reaction, Se reacts with the alkali solution to form Se 2- , Se is converted to 2 / 3Na 2 Se and 1 / 3Na 2 SeO 3 .

[0035] After the hydrothermal reaction is completed, the system is preferably cooled to room temperature, the excess Se powder is filtered to separate, and the liquid material is collected, i.e., the alkaline selenium-sulfur solution (containing Se 2- , SeO 3 2- and S 2- three ions).

[0036] In the present invention, in the selenium-sulfur solution, S 2- with Se 2- The molar ratio of Se powder and Na is preferably (0.2-5):1 and not 5:1, more preferably 1:5 or 3:3; 2 The molar ratio of S is preferably (2.12 to 6.35):(1.41 to 7.05), and more preferably 6.35:4.22.

[0037] After obtaining the selenium-sulfur solution, the present invention further comprises:2 The O cube powder is mixed with water, and the obtained suspension is mixed with a selenium-sulfur solution to carry out a selenization-sulfurization reaction to obtain an S-doped hollow copper selenide box.

[0038] In the present invention, the Cu 2 The method for preparing CuO cubic powder preferably comprises: mixing copper salt, alkali, glucose and water, and reducing them to obtain Cu 2 O cube powder.

[0039] In the present invention, the copper salt preferably includes copper sulfate, more preferably copper sulfate pentahydrate; the alkali preferably includes sodium hydroxide.

[0040] In the present invention, the mass ratio of the copper salt, the base and the glucose is preferably 7.5:3.6:4.2.

[0041] The present invention preferably dissolves the copper salt in part of the water, and under the set reduction temperature condition, the copper salt is completely dissolved by stirring, the alkali is dissolved in the remaining water, the obtained alkali solution is added to the copper salt solution, and the stirring is continued for 5 minutes before adding glucose to carry out reduction.

[0042] In the present invention, the reduction temperature is preferably 70° C., and the time is preferably 30 min; and the reduction is preferably carried out under stirring conditions.

[0043] After the reduction is completed, the present invention preferably collects the obtained product by centrifugation, filters the excess liquid, washes the product with deionized water, and vacuum dries it at 50° C. for 12 h to obtain Cu 2 O cube powder.

[0044] The present invention is directed to the Cu 2 There is no special limit on the ratio of CuO cube powder to water. 2 O cubic powder is fully dispersed and suspended; in the embodiment of the present invention, specifically 3.47mmolCu 2 The O cube powder was dispersed in 400 mL of deionized water by stirring.

[0045] In the present invention, the Cu 2 The molar ratio of O cubic powder to Se powder is preferably 3.47:(2.12-10.58), and more preferably 3.47:6.35.

[0046] In the present invention, the temperature of the selenization-sulfurization reaction is preferably room temperature, and the time is preferably 5 hours; the selenization-sulfurization reaction is preferably carried out under stirring conditions; the present invention has no special limitation on the stirring, and the reaction can be carried out smoothly according to the process well known in the art. During the selenization-sulfurization reaction, Cu 2 O cubes as sacrificial templates containing Na in selenium-sulfur solution2 Se plays a role in selenization of Cu 2 O to form copper selenide, while S 2- Doping penetration in Cu 2-x In the Se lattice, when the amount of S added is large, the excess S and Cu 2 O combines to form Cu 2-x S (copper sulfide).

[0047] After the selenization-sulfurization reaction is completed, the present invention preferably collects the product by suction filtration, then washes it with deionized water, and then vacuum dries the obtained product to obtain an S-doped hollow selenized copper box. The present invention has no particular limitation on the suction filtration and vacuum drying, and can be carried out according to processes well known in the art.

[0048] In the present invention, S not only participates in the regulation process in the form of a dopant, but also can control the S concentration to form a new phase. The S-induced new phase formation process is more prominent in the coordination of morphology, composition, heterogeneous interface, defect level and conductivity, resulting in excellent electromagnetic wave absorption performance of the material.

[0049] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0050] Examples 1 to 3 and Comparative Example 1

[0051] Table 1 Raw material dosage and selenization time in different cases

[0052]

[0053] 7.5 g CuSO 4 ·5H 2 O was dissolved in 300 mL of deionized water and completely dissolved under stirring at 70 °C. Then, 30 mL of the prepared NaOH solution (containing 3.6 g of NaOH) was added. After continuous stirring for 5 min, 4.2 g of glucose was added and the reaction was continued for 30 min. The product was collected by centrifugation, the excess liquid was filtered, and the product was washed with deionized water and dried under vacuum at 50 °C for 12 h to obtain Cu 2 O cubic powder;

[0054] Se powder (dosage see Table 1) and Na 2 S·9H 2 O (amount see Table 1) was dissolved in 50 mL of NaOH solution (concentration see Table 1), kept at 120 °C for 4 h, cooled naturally to room temperature, and the excess Se powder was filtered to collect the alkaline selenium-sulfur solution;

[0055] Take the prepared Cu 2O cubic powder 3.47mmol was dissolved in 400mL deionized water to obtain Cu 2 O suspension, under constant stirring, add the selenium-sulfur solution obtained 2 O suspension, stirred at room temperature for selenization (see Table 1 for selenization time), the product was collected by filtration, washed with deionized water, and the obtained product was vacuum dried to obtain a hollow selenized copper box.

[0056] Characterization and performance testing

[0057] 1) Scanning electron microscopy (SEM, ZEISS sigma500) and transmission electron microscopy (TEM, FEI-Tecnai G2 F20) were used to observe the surface and internal morphology of the samples prepared in different embodiments. X-ray powder diffraction (XRD, UltimalV, Cu / Kα), TEM-SEAD mode and EDS-Mapping energy spectrum (BRUKER XFlash 6130) were used to analyze the phase and composition of the samples.

[0058] Figure 1 Figure a is the XRD pattern of S-doped copper selenide boxes (S1-S3) with different sulfur contents. Figure 1 b is CuSe, CuS and Cu 7 S 4 The standard diffraction spectrum of Figure 1 It can be seen that when the molar ratio V(S 2- ):V(Se 2- )=1:5, despite the introduction of S element, the diffraction peak of S1 is almost the same as the standard diffraction spectrum of CuSe, except that the peak corresponding to the {110} crystal plane is slightly shifted to a higher angle. This indicates that the lattice parameter of S-doped CuSe becomes smaller because part of Se (1.98A) in S1 is replaced by S (1.84A) with a smaller ionic radius. It can be foreseen that the introduction of S element may be beneficial to breaking the Cu 2-x The symmetry of Se lattice leads to the formation of lattice defects. The dipoles induced by these defects will act as polarization centers to enhance dielectric polarization loss. However, as the proportion of S element increases, the characteristic peaks of copper selenide partially disappear (marked by solid circles). 2- ):V(Se 2- )=3:3, a new diffraction peak appears at 29.74°, corresponding to Cu 2 It is worth noting that, on the one hand, the diffraction peak of S2 at 46.09° corresponds exactly to the CuSe{110} crystal plane, and there is no shift in the diffraction peak, which indicates that there is almost no S ion replacing Se ion in S2. On the other hand, it is relatively 2 The S{573} crystal plane shifts slightly to a lower angle, indicating that Cu2 Some of the S ions in S may be replaced by Se ions. 2- ):V(Se 2- )=5:1, Cu 2 The S peak disappears completely, and the remaining diffraction peaks are similar to those of Cu 1.8 S characteristic peaks correspond well, indicating that Cu 2-x Cu in S 2 S successfully transitioned to Cu1.8S. Although S3 contained a small amount of Se, the diffraction peak of S3 did not shift significantly to a low angle, indicating that Se ions did not penetrate into Cu 1.8 S in the crystal lattice. This may be because the ionic radius of Se is too large, and it cannot smoothly replace the position of S when its concentration is very low, so it combines with Cu and exists independently as CuSe.

[0059] Figure 2 Middle (ac) is Cu doped with different S contents 2-x The morphology of Se boxes (S1-S3), the small figure in the upper right corner of (ac) is the corresponding TEM image, the scale bar is 0.5μm; Figure 2 From ac, we can see that when V(S 2- ):V(Se 2- )=1:5, S1 is in the shape of a braided ball, and the surface is loosely stacked by nano shuttles, which is smaller than the original Cu 2 The O template is too large. Its hollow part can be observed in TEM, but the hollow cavity is not obvious because the shell is thick. 2- ):V(Se 2- )=3:3, S2 is a perfect cube, and both the morphology and size are well inherited from the original Cu 2 O template. Due to the thin shell, many cubic cross-sections were observed in the SEM image, and obvious hollow parts and similar small cubes in the cubic cavity were observed in the TEM image. 2- ):V(Se 2- )=5:1, S3 is quasi-cube-shaped, with the face of the cube concave inwards, and there are also concave cubes in the inner cavity of the cube, which together form a double-shell cube. The formation of the hollow shell depends on the diffusion of copper ions outwards and the reaction with Se 2- or S 2- Combined with copper selenide (10 -48 ) than copper sulfide (10 -35 ) has a smaller solubility product constant, so copper selenide is easier to form than copper sulfide. It is speculated that the Kirkendall effect occurs twice in this process, driving the formation of copper selenide shell and copper sulfide shell respectively.

[0060] Figure 2The (df) in the figure are the EDS mapping spectra of S1-S3 and the corresponding element statistics. The colored dot matrix confirms the uniformity of element distribution. It can be found that with the increase of S content, the Cu content increases and the Se content decreases. The atomic number ratios (S:Se) of S1-S3 are 0.11, 0.52 and 3.50, respectively, which are significantly smaller than the preset V(S 2- ):V(Se 2- ), which indicates that the priority of copper selenide in the reaction process is higher than that of copper sulfide, which is consistent with the solubility product mentioned above. In addition, in S1, the sum of S and Se elements is approximately equal to Cu, indicating that only CuS and CuSe exist in S1, and it is possible that S element partially replaces Se lattice. In addition, CuSe+Cu 2 S(S2) and CuSe+Cu 1.8 The combination pattern of S(S3) is also consistent with the element statistics in ef. The above results confirm the validity of XRD analysis.

[0061] 2) Using N 2 Determination of S-doped Cu by adsorption-desorption method 2-x The specific surface area and pore size distribution of Se (S1-S3) are shown in Figure 3 , Figure 3 (ac) are N of S1-S3 respectively 2 Adsorption-desorption curve, the inset is the corresponding pore size distribution diagram; Figure 3 It can be seen that the three samples show type IV isotherms and the hysteresis loop is H3, indicating the presence of mesopores. The specific surface areas of S1-S3 are 29.41 m 2 / g, 58.99m 2 / g and 85.55m 2 / g, which is closely related to the degree of hollowing. According to the Barrrett Joyner-Halenda (BJH) model, the pore distribution range is 10-15nm.

[0062] Generally speaking, since metal selenides have better electronic conductivity than corresponding oxides or sulfides, the introduction of S may reduce the intrinsic conductivity of the product. However, for electromagnetic wave absorbing materials, it is necessary to mix the absorber and the matrix. The introduction of S elements in the cubic structure has a larger cavity volume and specific surface area, which reduces the particle density. Under the same filling mass, the volume fraction increases, it is easier to connect with each other, and it is easier to contact each other in the matrix to promote a conductive network, thereby improving the conductivity and showing stronger conductivity than selenide. This feature leads to a larger space to adjust electromagnetic parameters and optimize EMW absorption capacity.

[0063] 3) The complex dielectric constant of the sample at 2-18 GHz was measured using a vector network analyzer (VNA, PNA-N5234A). The sample powder was uniformly mixed with the paraffin matrix at different mass fractions and then pressed into a ring-shaped mold with an inner diameter of 3.04 mm and an outer diameter of 7.00 mm.

[0064] The copper selenide powder (T5) prepared in Comparative Example 1 and the samples S1 to S3 prepared in Examples 1 to 3 were filled in a paraffin matrix at different ratios to prepare sample / paraffin composite materials.

[0065] Figure 4 Where (ab) is the complex dielectric constant of T5, S1, S2 and S3 when the filling amount is 40wt%. Figure 4 As shown in (ab), compared with T5 / paraffin, after the introduction of S element, the ε′ of S1 / paraffin and S2 / paraffin decreased to a certain extent, which is beneficial to enhance their tanδ E And the ε″ value of S1 / paraffin shows an obvious dielectric resonance near 6.3GHz, which is attributed to the Cu 2-x Defects generated by S ion substitution in the Se lattice act as polarization centers and enhance polarization losses. In addition, it is also noted that the S3 / paraffin complex dielectric constant increases significantly, which may be attributed to two reasons. First, S3 has a significant double-shell structure and a large specific surface area, which is conducive to the construction of a conductive network and the response to electromagnetic waves. Second, the main component of S3 is Cu 1.8 S, there are copper vacancies, forming a large number of electron holes in the energy band, making it have excellent conductivity. To further study the relationship between conductivity and dielectric loss, the conductivity of T1, S1, S2, S3 and paraffin composites was tested, which were 0.45S / m, 0.21S / m, 0.38S / m and 3.02S / m, respectively. The conductivity of S1 / paraffin is lower than that of T5 / paraffin, mainly because the intrinsic conductivity of the material decreases after sulfur doping and the degree of hollowing decreases. After that, the conductivity of the composite increases with the increase of the proportion of S element, which is related to the increase of the specific surface area of ​​its microstructure. For most electromagnetic wave absorbing materials, the dielectric loss is determined by the polarization loss ε" P and conduction loss ε" C It consists of two parts. According to Debye theory, the calculation formula of ε″ value is as follows:

[0066]

[0067] Where ω is the angular frequency (ω = 2πf), τ is the relaxation time, σ is the conductivity (S / m), and ε 0 is the free space dielectric constant (8.854×10 -12F / m), ε ∞ and ε s They represent the dielectric constant in the high frequency limit and the static dielectric constant respectively.

[0068] Figure 4 (cd) is the ε of the composite materials of T5, S1, S2 and S3 with paraffin" C and ε" P Plotted against frequency, subtract ε" from ε" C The corresponding ε" P Value. Figure 4 From (cd), we can see that for T1 and S3, at the initial frequency (2GHz), their dielectric loss is almost entirely contributed by the conductive loss. As the frequency increases, ε" P It gradually increases, which is due to the fact that the dielectric polarization cannot catch up with the alternating electric field at high frequency and relaxes. For S1 and S2, there is a certain polarization loss at 2GHz, which proves the existence of defect polarization caused by ion substitution, that is, part of Se is replaced by S or part of S is replaced by Se.

[0069] Figure 5 (a1, b1, c1) are the three-dimensional reflection loss diagrams of S1, S2, S3 and paraffin composite materials, (a2, b2, c2) are the two-dimensional reflection loss diagrams of S1, S2, S3 and paraffin composite materials, and (a3, b3, c3) are the effective bandwidth / reflection loss-thickness histograms of S1, S2, S3 and paraffin composite materials.

[0070] As we all know, when R L When the value exceeds -10dB, 90% of the electromagnetic waves can be dissipated by the absorber, which is called the effective absorption band (EAB). Figure 5 As shown, the R of S1 / paraffin Lmin At 2.7 mm, it is -46.3 dB, and the corresponding EAB is 3 GHz. With the doping of S elements, its structure evolves into a double-shell cube, and the R of S2 / paraffin Lmin The S1 has a good R L -Thickness stability, R in the range of 2.1-2.9mm L The values ​​are all over -20dB. On the other hand, S2 shows good EAB-thickness stability, and its EAB value is over 4GHz in the range of 1.7-2.5mm. However, although S3 has a rare structure, its high conductivity prevents electromagnetic waves from entering the absorber, so it cannot effectively absorb electromagnetic waves.

[0071] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for improving the electromagnetic wave absorption performance of a hollow copper selenide box, It is characterized in that The following steps are involved: Se powder, Na 2 S is mixed with alkali solution and subjected to hydrothermal reaction to obtain a selenium-sulfur solution; Mix Cu 2 O cubic powder with water, mix the resulting suspension with a selenium-sulfur solution, and carry out a selenization-sulfuration reaction to obtain S-doped hollow copper selenide boxes; The usage ratio of the Se powder to the alkali solution is (2.12-6.35) mmol:50 mL; the concentration of the alkali solution is 10 mol / L; The temperature of the hydrothermal reaction is 120°C and the time is 4h; The Cu 2 The preparation method of CuO cubic powder includes: mixing copper salt, alkali, glucose and water, reducing the mixture to obtain Cu 2 O cube powder; The copper salt includes copper sulfate, and the alkali includes sodium hydroxide; the mass ratio of the copper salt, the alkali and the glucose is 7.5:3.6:4.2; The reduction temperature is 70°C and the time is 30 minutes; In the selenium-sulfur solution, S 2- with Se 2- The molar ratio is (0.2-5):1 and not 5:1; The Cu 2 The molar ratio of O cubic powder to Se powder is 3.47:(2.12~6.35).

2. The method according to claim 1, It is characterized in that In the selenium-sulfur solution, S 2- with Se 2- The molar ratio is 1:5 or 3:

3.

3. The method according to claim 1, It is characterized in that The temperature of the selenization-sulfurization reaction is room temperature and the time is 5 hours.

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