Preparation and application of Schottky coupling homojunction semiconductor material

Abstract

The invention discloses preparation and application of a Schottky coupling homojunction semiconductor material, and belongs to the technical field of semiconductor materials.The preparation method of the Schottky coupling homojunction semiconductor material comprises the following steps that a CdS nanorod is synthesized through a hydrothermal method, then, CdS quantum dots are synthesized on the CdS nanorods in situ through a hydrothermal method, so that CdS homojunctions are obtained, and finally, the gold nanoparticles are coupled with the CdS homojunctions. According to the invention, the S-type homojunction and the Schottky junction are innovatively combined to form a synergistic effect of'efficient separation + plasma amplification ', and the signal leap-type promotion is realized, so that the self-powered photoelectrochemical sensor prepared based on the material has higher detection sensitivity and has great potential in the development of portable sensing equipment.

Description

Preparation and application of a Schottky-coupled homojunction semiconductor material Technical Field

[0001] This invention relates to the field of semiconductor materials technology, specifically to a method for preparing Schottky-coupled homojunction semiconductor materials and their applications. Background Technology

[0002] Self-powered photoelectrochemical (PEC) sensors based on semiconductor materials show great potential in the development of novel portable sensing devices. They can operate without an external power supply, avoiding interference from background noise and preventing damage to the electrode surface from high voltage, thus laying the foundation for field detection applications. However, the inherently low photoelectric conversion efficiency of single semiconductors leads to insufficient sensitivity of self-powered PEC sensors under unbiased conditions, limiting their further development.

[0003] Currently, most self-powered PEC sensors rely on heterojunctions for signal amplification because the feasibility and effectiveness of spatially separating electron-hole pairs in heterostructures have been widely verified. Among them, S-type heterojunctions have attracted much attention due to their strong interface driving force and redox capability, especially when constructed using in-situ growth methods, where tight interface contacts can further promote carrier migration. Nevertheless, traditional semiconductor heterojunctions (such as TiO2 / CdS, ZnO / CdSe, etc.) still face insurmountable key problems, the core issue being lattice mismatch: the significant differences in elemental composition between different components lead to inconsistent lattice parameters and interplanar spacing, resulting in a large number of defect states forming at the heterojunction interface, making it impossible to achieve tight interfacial electronic coupling. This not only hinders the cross-interface transfer of photogenerated carriers but also forms charge recombination centers, significantly reducing photoelectric conversion efficiency. These shortcomings directly lead to two major application challenges: First, the detection system is highly complex. To drive charge transfer or maintain stability, traditional heterojunction PEC sensors usually require the application of external bias voltage or the addition of sacrificial agents (such as ascorbic acid or triethanolamine), which is cumbersome and cannot meet the requirements for portable, self-powered on-site detection. Second, the sensitivity is difficult to meet the standards. Due to low photoelectric conversion efficiency and severe interface charge loss, the sensor has a weak response signal to low concentrations of clinical biomarkers such as C-reactive protein (CRP) and a high detection limit, which cannot meet the actual needs of early clinical diagnosis and accurate detection.

[0004] Therefore, developing novel semiconductor materials suitable for self-powered PEC sensors is of great significance for the on-site detection of biomarkers. Summary of the Invention

[0005] In view of the technical problems existing in the background art, the present invention provides a method for preparing and applying a Schottky-coupled homojunction semiconductor material, aiming to solve the technical problem of insufficient sensitivity of self-powered PEC sensors caused by the low electrical conversion efficiency of existing semiconductor materials.

[0006] To achieve the above-mentioned technical objectives, the present invention specifically adopts the following technical solution: a Schottky-coupled homojunction semiconductor material, which is obtained by coupling gold nanoparticles with a cadmium sulfide homojunction, denoted as Au-CdS. QR The preparation method includes the following steps: S1, synthesizing CdS nanorods (CdS NRs) using a hydrothermal method; S2, synthesizing CdS quantum dots (CdS QDs) in situ on CdS NRs using a hydrothermal method, thereby obtaining CdS homojunctions (CdS NRs). QR S3, making gold nanoparticles (Au NPs) and CdS QR Coupling, thus obtaining Au-CdS QR .

[0007] Preferably, in the above preparation method, the CdS NRs synthesized by hydrothermal method are 300-500 nm long and 30-50 nm in diameter. In some embodiments of the present invention, CdCl2 and NH2CSNH2 are added to ethylenediamine and CdS NRs are synthesized in a high-pressure reactor at 160°C.

[0008] Preferably, in the above preparation method, the size of CdS QDs is 4-6 nm, and the homojunction CdS QR The loading of CdS QDs is 5-60%. In some embodiments of the present invention, step S2 specifically involves: dispersing CdS NRs in ethanol, adding Cd(CH3COO)2 in the corresponding stoichiometric ratio and an equimolar amount of NH2CSNH2, and synthesizing CdSQDs in a high-pressure reactor at 120°C.

[0009] Preferably, in the above preparation method, the size of Au NPs is 15-25 nm, and the Au NPs and CdS QR The mass ratio is 1:5-1:10.

[0010] Preferably, in the above preparation method, step S3 uses a surface drop-coating coupling method to couple Au NPs with CdS. QR Coupling. This method allows Au NPs to uniformly cover the homojunction surface, ensuring effective Schottky junction formation and laying the foundation for significantly enhanced sensor sensitivity. In some embodiments of the present invention, step S3 specifically involves: applying CdS... QR A dispersion of Au NPs was coated onto the surface of an electrode (such as an ITO electrode), dried at 50°C, and then Au-CdS solution was dropwise onto the electrode surface to obtain Au-CdS. QR electrode.

[0011] Furthermore, the present invention provides Au-CdS QRIn the application of the preparation of ultrasensitive self-powered PEC sensors, the resulting self-powered PEC sensors can detect target substances without external bias voltage and sacrificial agents.

[0012] Specifically, using Au-CdS QR The method for preparing an ultrasensitive self-powered PEC sensor includes the following steps: (1) taking an aptamer solution and drop-coating it onto Au-CdS QR The electrode surface is washed to remove unbound aptamers and dried; wherein the aptamer can specifically bind with the target substance to form a complex and can be bound to the electrode surface through chemical bonds; (2) the non-specific binding sites on the electrode surface are sealed, and the sealing reagent is washed to remove the sealing reagent, thus obtaining a self-powered PEC sensor that can be used to detect the target substance.

[0013] Preferably, in the above applications, washing is performed using PBS with pH 7.2-7.4, and drying is performed using nitrogen blowing.

[0014] Preferably, in the above applications, the target substance includes, but is not limited to, CRP.

[0015] Preferably, in the above applications, 1-hexanethiol is used to seal the electrode surface.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. Signal enhancement is achieved through lattice matching and S-type carrier migration path.

[0017] This invention utilizes the same synthesis method to construct lattice-matched S-type CdS homojunctions under different reaction conditions, which can ensure that the crystal structure and lattice parameters are completely consistent, significantly reducing interface defects and carrier recombination centers. At the same time, the S-type charge transfer path provides a strong interface driving force, enabling the directional and efficient separation of photogenerated hole pairs, and improving the photocurrent response by 15 times compared with the original CdSNRs.

[0018] 2. Schottky coupling and synergistic amplification achieve a leapfrog improvement in signal strength.

[0019] This invention innovatively combines an S-type homojunction with a Schottky junction to form a synergistic effect of "high-efficiency separation + plasma amplification", which improves the photoelectric signal by 31 times compared with the original material, far exceeding the enhancement effect of a single structure.

[0020] 3. A breakthrough in detection limits has been achieved.

[0021] The strong signal output of this invention compensates for the lack of bias voltage, with a CRP detection limit as low as 5 pg / mL and a linear range covering 0.025-1.0 ng / mL, enabling accurate capture of low-concentration target substances.

[0022] 4. The ultra-sensitive self-powered PEC sensor enables stable self-powered energy storage.

[0023] This invention requires no external power source or sacrificial agent. In-situ growth makes the structure more stable, maintaining both self-powered portability and extended service life, making it suitable for practical testing scenarios. Attached Figure Description

[0024] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0025] Figure 1 shows Au-CdS in Example 1. QR The synthesis route map.

[0026] Figure 2 shows electron microscope images of the CdS NRs prepared in Example 1, where a is a scanning electron microscope image, b is a transmission electron microscope image, and c is a high-resolution transmission electron microscope image.

[0027] Figure 3 shows the CdS prepared in Example 1. QR Transmission electron microscope image (a) and high-resolution transmission electron microscope image (b).

[0028] Figure 4 shows the CdS NRs and CdS in Example 1. QR X-ray powder diffraction pattern.

[0029] Figure 5 shows the CdS obtained under different CdS QDs loading in Example 1. QR A comparison chart of their photoelectric properties.

[0030] Figure 6 shows the CdS NRs and CdS in Example 1. QR Au-CdS NRs and Au-CdS QR A comparison chart of their photoelectric properties.

[0031] Figure 7 shows the relationship between the photocurrent intensity of the self-powered PEC sensor prepared in Example 2 and the CRP concentration in the sample.

[0032] Figure 8 shows the selectivity test diagram of the self-powered PEC sensor prepared in Example 2 for CRP. Detailed Implementation

[0033] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the specification and claims of this invention are intended to cover non-exclusive inclusion.

[0035] The low photoelectric conversion efficiency of semiconductor materials limits the further development of self-powered PEC sensors. To address this technical problem, the first aspect of this invention provides a CdS₂ material with perfectly matched lattice and an S-shaped charge transfer path. QR CdS NRs were first synthesized via a hydrothermal method, and then CdS QDs were grown in situ on the CdS NRs using an in-situ hydrothermal method. X-ray diffraction and high-resolution transmission electron microscopy confirmed that the two components had highly consistent crystal structures and lattice fringes, which is attributed to their identical chemical composition and synthesis route. Moreover, the photoelectrochemical performance of the homojunction under the optimal CdS QDs loading conditions was improved by 17 times compared with the original CdS NRs.

[0036] A second aspect of the present invention provides a gold-coupled cadmium sulfide homojunction, namely Au-CdS QR Specifically, it can be prepared via surface drop-coating coupling. This hybrid structure exhibits a synergistic enhancement effect: gold-modified CdS NRs alone (Au-CdSNRs) improve the photoelectric response by 1.5 times, while CdS... QR It was enhanced by 17 times, and the combination of the two (Au-CdS) QR This resulted in a 31-fold performance improvement. Furthermore, the drop-coating method facilitates a larger contact area for subsequent sensing applications, further enhancing the sensor's sensitivity.

[0037] A third aspect of this invention provides an ultrasensitive, self-powered PEC sensor, specifically by immobilizing a specific aptamer of the target substance onto Au-CdS via chemical bonds. QR The electrode surface enables high-affinity selective recognition of target substances. This sensor requires no external power source or sacrificial agent, allowing for accurate detection of low concentrations of target substances.

[0038] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0039] Example 1 This example provides a Schottky coupled homojunction semiconductor material, as shown in Figure 1. Its preparation method includes the following steps: (1) Preparation of CdS NRs.

[0040] 2.3 g of CdCl2·2.5H2O and 4.5 g of NH2CSNH2 were dissolved in 60 mL of ethylenediamine. After sonicating the mixture for 30 minutes, it was transferred to a 100 mL polytetrafluoroethylene-lined reactor and reacted at 160 °C for 48 hours. After cooling to room temperature, the yellow precipitate was collected by centrifugation. The precipitate was washed three times alternately with deionized water and ethanol, and then freeze-dried to obtain the final product CdS NRs.

[0041] (2) CdS QR Preparation of .

[0042] CdS QDs were prepared by in-situ growth of CdS NRs on CdS NRs using an in-situ hydrothermal method. QR To investigate the effect of quantum dot loading, samples with theoretical quantum dot mass fractions relative to the CdS NRs support of 5%, 10%, 20%, 40%, and 60% were prepared. The specific preparation process is as follows: 0.25 g of CdS NRs was dispersed in 70 mL of ethanol and sonicated for 0.5 hours to form a homogeneous suspension. Under continuous vigorous magnetic stirring, Cd(CH3COO)2·2H2O was added in the appropriate stoichiometric ratio, followed by an equimolar amount of NH2CSNH2. The resulting mixture was transferred to a polytetrafluoroethylene-lined high-pressure reactor and reacted at 120 °C for 10 hours. After the reaction, the yellow precipitate was collected by centrifugation (6000 rpm, 15 minutes), washed three times with deionized water and anhydrous ethanol, and freeze-dried to obtain the final product, CdS NRs. QR .

[0043] (3) Gold-coupled cadmium sulfide homojunction (Au-CdS) QR Preparation of ).

[0044] Add 70 μL of 1.0 wt% HAuCl4 solution to 40 mL of deionized water, sonicate for 10 minutes, and then stir at room temperature for 2 hours. Next, rapidly add 500 μL of freshly prepared 0.01 M NaBH4 solution to the suspension and continue stirring for 20 minutes. Then, gradually add 200 μL of 0.01 M sodium citrate solution to the reaction system and continue stirring for 30 minutes. After the reaction is complete, collect the product by centrifugation and wash to obtain Au NPs.

[0045] 10 μL of prepared CdS QRA dispersion (5 mg / mL) was coated onto the pretreated ITO electrode surface and dried at 50 °C. Finally, 10 μL of Au NPs solution (0.5 mg / mL) was added dropwise to the electrode surface to obtain Au-CdS. QR electrode.

[0046] The products prepared in each of the above steps were subjected to electron microscopy, X-ray diffraction, and photoelectric property analysis, and the results are as follows: Figure 2a and Figure 2b are scanning electron microscope images and transmission electron microscope images of CdS NRs, respectively, indicating that CdS NRs were successfully prepared in this example; Figure 2c is a high-resolution transmission electron microscope image of CdS NRs, showing that the interplanar spacings in CdS NRs are 0.248 nm and 0.331 nm, respectively.

[0047] Figure 3a shows CdS QR Transmission electron microscopy images show that CdS QR The nanorod structure is preserved; Figure 3b shows CdS QR The high-resolution transmission electron microscope images clearly show that CdS QDs are grown in situ on CdS NRs, and their interplanar spacing is 0.248 nm, consistent with that of CdS NRs; the consistent interplanar spacing provides direct evidence for the perfect interface matching of the homojunction.

[0048] Figure 4 shows CdS NRs and CdS QR The X-ray diffraction pattern of CdS NRs shows that the characteristic peaks of CdS NRs are consistent with those of CdS (JCPDS No. 77-2306); CdS QR The spectra of the two materials match well with those of CdS NRs, confirming that they have the same crystal structure and providing direct evidence for the good matching of lattice interfaces in homojunctions.

[0049] Figure 5 shows the CdS obtained under different CdS QDs loading. QR The photoelectric performance comparison showed that the optimal photocurrent was obtained when the CdS QDs loading reached 40 wt%.

[0050] Figure 6 shows CdS NRs and CdS QR Au-CdS NRs and Au-CdS QR A comparison of photoelectric properties, among which CdS QR The quantum dot loading was 40 wt%, and the preparation method of Au-CdS NRs was the same as that of Au-CdS QR During the preparation process, CdS QR Simply replace the dispersion with a CdS NRs dispersion. It is worth noting that Au-CdS... QRThe photocurrent was 8.5 μA, a 31-fold improvement compared to the original CdS NRs (0.27 A); this performance exhibits a synergistic enhancement effect, as it significantly outperforms CdS NRs. QR The improvements observed in Au-CdS NRs (4.6 μA, a 17-fold improvement compared to CdS NRs) and Au-CdS NRs (0.4 μA, a 1.5-fold improvement compared to CdS NRs).

[0051] Example 2: This example uses CRP as an example to provide a self-powered PEC sensor that does not require external bias voltage or sacrificial agent. The preparation method is as follows: Take 10 μL of CRP aptamer (i.e., anti-CRP antibody) solution (2 μM) and drop it onto the prefabricated electrode (Au-CdS prepared in Example 1). QR Electrode, in which CdS QR The surface of the aptamer was loaded with 40 wt% quantum dots and incubated overnight at 4 °C to achieve thiol-gold bond binding. Unbound aptamers were removed by washing three times with PBS (pH 7.2-7.4) and then dried with nitrogen. Surface passivation was performed to block non-specific binding sites by adding 10 μL of 0.1 mM 1-hexanethiol solution to the aptamer-functionalized electrode surface and incubating at 37 °C for 20 minutes. Excess reagent was then removed by washing with PBS to minimize background interference.

[0052] The following tests were performed on the prepared self-powered PEC sensor: (1) linearity and detection limit tests.

[0053] Add 10 μL of CRP solution of different concentrations (0, 0.025, 0.050, 0.10, 0.20, 0.50, 1.0, 2.0, 5.0 ng / mL) to the surface of the modified electrode, and incubate at 37°C for 30 minutes to allow the aptamer to specifically bind to CRP and form a complex; wash with PBS to remove unbound CRP, and air dry the electrode before performing PEC testing.

[0054] The test results are shown in Figure 7: the photocurrent response initially increases with CRP concentration between 0 and 1 ng / mL, and then decreases between 1 and 5 ng / mL (Figure 7a). This trend may be attributed to the reaction between CRP and holes at low concentrations, and the steric hindrance effect at high concentrations. The photocurrent is linearly correlated with CRP in the range of 0.01–1 ng / mL (Figure 7b), and the linear fitting equation is I(μA) = 3.34 + 3.89 C CRP (R² = 0.98), the limit of detection (S / N = 3) was 5 pg / mL.

[0055] (2) Specificity test.

[0056] To evaluate the selectivity of the prepared PEC sensor for CRP, its photocurrent response to other potentially common compounds present in the test samples (such as bovine serum albumin (BSA), prostate-specific antigen (PSA), carcinoembryonic antigen (CEA), and immunoglobulin G (IgG)) was investigated. The measurement procedure followed standard PEC detection protocols for CRP, with each interfering substance prepared as a 5 ng / mL solution.

[0057] The test results are shown in Figure 8: the prepared PEC sensor has excellent selectivity for interference that may exist in the human body.

[0058] It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments that have the same structure and perform the same effects as the technical concept within the scope of the present invention are included within the scope of the present invention. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of the present invention, are also included within the scope of the present invention.

Claims

1. A method for preparing a Schottky-coupled homojunction semiconductor material, characterized in that, Includes the following steps: S1. CdS nanorods were synthesized using a hydrothermal method; S2. CdS quantum dots are synthesized in situ on CdS nanorods using a hydrothermal method to obtain a CdS homojunction; S3. Gold nanoparticles are coupled with the CdS homojunction to obtain a Schottky-coupled homojunction semiconductor material.

2. The preparation method according to claim 1, characterized in that, The CdS nanorods are 300-500 nm long and 30-50 nm in diameter.

3. The preparation method according to claim 1, characterized in that, In the CdS homojunction, the loading of CdS quantum dots is 5-60% of the mass of CdS nanorods.

4. The preparation method according to claim 1 or 3, characterized in that, The size of the CdS quantum dots is 4-6 nm.

5. The preparation method according to claim 1, characterized in that, Step S3 uses a surface drop-coating coupling method to couple gold nanoparticles with a CdS homojunction. The size of the gold nanoparticles is 15-25 nm, and the mass ratio of the gold nanoparticles to the CdS homojunction is 1:5-1:

10.

6. The Schottky-coupled homojunction semiconductor material prepared according to claims 1-5.

7. The application of the Schottky-coupled homojunction semiconductor material as described in claim 6 in the fabrication of a self-powered photoelectrochemical sensor.

8. The application according to claim 7, characterized in that, Specifically, the aptamer solution is drop-coated onto the electrode surface containing the Schottky-coupled homojunction semiconductor material. Unbound aptamers are washed away and dried. Then, the non-specific binding sites on the electrode surface are sealed to obtain a self-powered photoelectrochemical sensor that can be used to detect target substances. The aptamer can specifically bind with the target substance to form a complex and can be chemically bonded to the electrode surface.

9. The application according to claim 8, characterized in that, The target substance includes C-reactive protein.

10. The application according to claim 8, characterized in that, The electrode surface was sealed using 1-hexanethiol.

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