Preparation, layer thickness control method and photoelectric detection application of a two-dimensional rhombohedral phase ZnIn2S4 nanosheet array photoanode

Abstract

The present invention provides a method for preparing and controlling the layer thickness of a two-dimensional rhombic phase ZnIn2S4 nanosheet array photoanode and its application in photoelectric detection. On a clean conductive substrate FTO, an aqueous solution including ZnCl2, InCl3·4H2O, and CH4N2S is used as a precursor solution, and a ZnIn2S4 nanosheet array photoanode is in-situ prepared directly through a one-step simple hydrothermal method. The PEC-type self-powered photodetector based on ZnIn2S4 includes an electrolyte, a reference electrode, a working electrode, and a counter electrode, and the working electrode is the ZnIn2S4 nanosheet array photoanode. The present invention develops a confinement growth method based on the concentration regulation of thiourea to bidirectionally control the stacking of ZnIn2S4 atomic layers, and thus prepares a ZnIn2S4 PEC-type self-powered photodetector based on ZnIn2S4 with different numbers of layers. According to the tunable optoelectronic properties of ZnIn2S4 with different numbers of layers, broadband photoelectric detection and ultraviolet photoelectric detection are realized.

Description

Technical Field

[0001] The present invention belongs to the field of photoelectric detection, and specifically relates to a two-dimensional rhombohedral phase ZnIn 2 S 4 Preparation of nanosheet array photoanodes, layer thickness control methods and photoelectric detection applications. Background Art

[0002] Two-dimensional (2D) spatial confinement endows layered van-der-Waals materials with unique electronic and optoelectronic properties, which have attracted great research attention in the fields of information devices and energy conversion. One of the most fascinating properties of 2D materials is the layer-number dependence of the electronic structure caused by the interlayer coupling effect, which provides an opportunity to easily tune their band structure and optoelectronic properties for multifunctional applications. In-depth exploration of the relationship between the number of layers and the electronic structure will enable precise control of the photogenerated carrier dynamics, including the generation, separation and interface transfer behavior of photogenerated carriers, thereby optimizing and expanding their optoelectronic applications.

[0003] As a typical member of the emerging two-dimensional ternary metal chalcogenides (TMCs), ZnIn with layered hexagonal and rhombohedral crystal structures 2 S 4 Compared with other two-dimensional materials (such as BP and TMDs), ZnIn has superior optoelectronic properties, high conduction band bottom position, rich tunability and more ideal chemical stability, so it has broad application prospects in the field of solar energy conversion as a semiconductor photocatalyst. In addition, the two-dimensional morphology not only makes ZnIn 2 S 4 The large specific surface area also shortens the diffusion distance of carriers to the surface, which is beneficial to heterogeneous interface coupling and interfacial carrier transport with other semiconductors or electrolytes. Although various strategies including doping with heteroatoms and incorporating vacancies have been adopted to adjust its electronic structure to further optimize photocarrier dynamics and improve photon utilization, the fascinating strategy of controlling layer thickness, which is only allowed by two-dimensional materials, has not been widely used in ZnIn. 2 S 4 It remains almost unexplored.

[0004] Although ZnIn 2 S 4 As a two-dimensional material, ZnIn has excellent photoelectric properties, fast response and low dark current, but its application in the field of photodetection is almost blank. In recent years, photoelectrochemical (PEC) type photodetectors (PDs) with simple device structure have become ideal candidate materials for realizing self-powered functions, which is in line with the development trend of low energy consumption. 2 S 4These advantages show great potential in PEC-type PDs. The more common application scenarios of PEC-type photodetectors are highly integrated broadband light detection and deep ultraviolet light detection for underwater optical communications. 2 S 4 The layer-band structure provides an opportunity to integrate both applications into one semiconductor. Summary of the invention

[0005] For ZnIn 2 S 4 The present invention aims to provide a two-dimensional rhombohedral phase ZnIn 2 S 4 Preparation of nanosheet array photoanode, layer thickness control method and photoelectric detection application. ZnIn with different layer thicknesses was grown in situ on the conductive substrate FTO by a one-step simple hydrothermal method with controlled thiourea concentration. 2 S 4 Nanosheet arrays based on ZnIn with different layer thicknesses 2 S 4 Prepared ZnIn 2 S 4 PEC-type self-powered photodetector realizes ZnIn 2 S 4 Bidirectional regulation of the photodetection performance of PEC-type self-powered photodetectors. On the one hand, multilayer ZnIn 2 S 4 By broadening the wavelength and improving the light response, the effect of wide spectrum detection can be achieved. On the other hand, single-layer ZnIn 2 S 4 The UV detection performance is optimized.

[0006] The present invention provides a two-dimensional rhombohedral phase ZnIn 2 S 4 The method for preparing a nanosheet array photoanode comprises the following steps:

[0007] (1) Obtain clean conductive glass FTO;

[0008] (2) Mix the following raw materials according to the preset ratio: ZnCl 2 、InCl 3 ·4H 2 O and CH 4 N 2 S, dissolved in water to obtain a precursor solution;

[0009] (3) subjecting the conductive glass FTO conductive surface described in step (1) to plasma surface treatment;

[0010] Within the effective time after the plasma surface treatment, two FTO sheets are placed in a reaction container with the conductive surface facing downward in a "V" shape, and the precursor solution prepared in step (2) is added to perform a hydrothermal reaction to obtain a two-dimensional rhombohedral ZnIn phase on the conductive surface of the conductive glass FTO. 2 S 4 Nanosheet arrays;

[0011] Conductive glass FTO together with the conductive surface of conductive glass FTO to obtain a two-dimensional rhombohedral phase ZnIn 2 S 4 Nanosheet arrays, together as photoanodes, are used to make working electrodes for PEC-type self-powered photodetectors; the prepared two-dimensional rhombohedral ZnIn 2 S 4 The nanosheet array photoanode comprises: conductive glass FTO and a two-dimensional rhombus phase ZnIn in-situ grown on the conductive surface of the conductive glass FTO 2 S 4 Nanosheet array; the two-dimensional rhombohedral phase ZnIn 2 S 4 Nanosheet arrays are composed of two-dimensional rhombohedral ZnIn 2 S 4 Nanosheet stacking composition; the two-dimensional rhombohedral phase ZnIn 2 S 4 The layer thickness of the nanosheets is 4 nm to 44.8 nm.

[0012] Layered rhombohedral phase structure of ZnIn 2 S 4 Due to their superior optoelectronic properties, high CBM positions, rich tunability and more desirable chemical stability than other 2D materials (e.g. BP, TMDs), they have shown great promise as semiconductor photocatalysts in solar energy conversion in recent years. In order to further optimize the photocarrier dynamics and improve the photon utilization, various strategies such as heteroatom doping and vacancy incorporation have been adopted to tune their electronic structure, but controlling the layer thickness, a fascinating strategy only allowed in 2D materials, has hardly been fully explored.

[0013] Preferably, in step (2), the setting of the preset ratio comprises the following steps:

[0014] Obtaining the wavelength range of the detection target of the PEC type self-powered photoelectric detector; setting the preset ratio according to the wavelength range of the detection target;

[0015] When the wavelength range of the detection target is 355-765nm, the ZnCl 2 、InCl 3 ·4H 2 O and CH 4 N 2The preset molar ratio of S is: 1:2:4;

[0016] When the wavelength range of the detection target is 254-355nm, the ZnCl 2 、InCl 3 ·4H 2 O and CH 4 N 2 The preset molar ratio of S is: 1:2:16.

[0017] Preferably, in step (3), the reaction container is a polytetrafluoroethylene liner; the hydrothermal reaction specifically includes: placing the polytetrafluoroethylene liner in a high-pressure reactor and performing a hydrothermal reaction at a temperature of 170°C for 12 hours; the plasma treatment specifically includes the following steps: treating in a plasma cleaner with a power of 60W and a time of 120s; the effective time refers to the time after the plasma treatment when the surface of the conductive glass FTO has energy within a certain period of time, which can promote the growth of the compound on the FTO surface, and the effective time is 10 minutes.

[0018] The present invention also provides a two-dimensional rhombohedral phase ZnIn 2 S 4 The photoelectric detection application of the nanosheet array photoanode includes the following steps:

[0019] Constructing a PEC-type self-powered photodetector using the two-dimensional rhombohedral phase ZnIn 2 S 4 Nanosheet array photoanode as the working electrode of PEC-type self-powered photodetector;

[0020] The PEC type self-powered photoelectric detector also includes an electrochemical workstation, an electrolyte tank, a reference electrode and a counter electrode; an electrolyte is provided in the electrolyte tank, and the reference electrode, the working electrode and the counter electrode are suspended in the electrolyte tank, all in contact with the electrolyte, and none of them touch the bottom of the electrolyte tank;

[0021] The working electrode is connected to the positive pole of the power supply of the electrochemical workstation, the counter electrode is connected to the negative pole of the power supply of the electrochemical workstation, and the reference electrode is connected to the reference potentiometer of the electrochemical workstation.

[0022] Preferably, the electrolyte in the electrolyte is 0.5M Na 2 SO 4 and 0.2M Na 2 SO 3 ; The reference electrode is an Ag / AgCl electrode; and the counter electrode is a Pt electrode.

[0023] The present invention also provides a two-dimensional rhombohedral phase ZnIn 2 S 4A method for controlling the layer thickness of a nanosheet array photoanode, wherein the two-dimensional rhombohedral ZnIn 2 S 4 Nanosheet array photoanode using the two-dimensional rhombohedral phase ZnIn 2 S 4 Preparation method of nanosheet array photoanode, by adjusting the preset ratio in step (2) to adjust the two-dimensional rhombus phase ZnIn obtained on the conductive surface of conductive glass FTO in step (3) 2 S 4 The thickness of the nanosheet; when the ZnCl 2 、InCl 3 ·4H 2 O and CH 4 N 2 When the preset molar ratio of S is 1:2:4, the two-dimensional rhombohedral phase ZnIn 2 S 4 The thickness of the nanosheet is 44.8 nm; when the ZnCl 2 、InCl 3 ·4H 2 O and CH 4 N 2 When the preset molar ratio of S is 1:2:8, the two-dimensional rhombohedral phase ZnIn 2 S 4 The thickness of the nanosheet is 18.6 nm; when the ZnCl 2 、InCl 3 ·4H 2 O and CH 4 N 2 When the preset molar ratio of S is 1:2:12, the two-dimensional rhombohedral phase ZnIn 2 S 4 The thickness of the nanosheet is 11.5 nm; when the ZnCl 2 、InCl 3 ·4H 2 O and CH 4 N 2 When the preset molar ratio of S is 1:2:16, the two-dimensional rhombohedral phase ZnIn 2 S 4 The layer thickness of the nanosheets is 4 nm.

[0024] Therefore, the present invention is based on regulating the two-dimensional rhombohedral phase ZnIn 2 S 4 The atomic layer stacking can adjust its band structure and optoelectronic properties, and further produce ZnIn 2 S 4 The wide spectrum and ultraviolet PEC type self-powered photodetector is a novel photodetector combining ZnIn 2 S4 The excellent photoelectric properties, self-powered properties, fast response and low dark current, as well as the regulation of the band structure and photoelectric properties, make the photodetector have ultra-high light response and detection rate without external bias. 2 S 4 A semiconductor that further expands the application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the specific implementation of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the specific implementation or the prior art description. Some specific embodiments of the present invention will be described in detail in an exemplary but not restrictive manner with reference to the drawings. The same reference numerals in the drawings indicate the same or similar components or parts. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0026] Figure 1 a, b, c, and d are respectively ZnIn with different precursor ratios prepared in Examples 1, 2, 3, and 4 of the present invention. 2 S 4 Scanning electron microscope images of nanosheets. All prepared photoanodes are high-quality, large-area, two-dimensional nanosheet structures vertically distributed on the FTO surface. 2 S 4 The thickness of the nanosheets gradually becomes thinner, evolving from the relatively straight thick nanosheets of ZIS-4TU to the wrinkled, cicada-wing-thin nanosheets of ZIS-16TU.

[0027] Figure 2 The different precursor ratios of ZnIn prepared in Examples 1, 2, 3, and 4 of the present invention are 2 S 4 X-ray diffraction patterns (XRD) of nanosheets. After removing the characteristic diffraction peaks of the FTO substrate, the remaining diffraction peaks of ZIS-4TU, ZIS-8TU, ZIS-12TU, and ZIS-16TU are all consistent with the rhombohedral phase ZnIn 2 S 4 (JCPDS card no.72-1445) corresponding to ((009), (012), (104), (015), (018), (110), (119), (202) are all rhombohedral phase ZnIn 2 S 4 The characteristic diffraction peaks of ZnIn were not detected, and no other phases and impurity peaks were detected, indicating that the synthesized rhombohedral phase ZnIn 2 S 4The purity is very high and the sharp diffraction peaks indicate that the synthesized product has good crystallinity. 2 S 4 The (104) and (110) peak intensities gradually weaken due to the decrease of layer thickness and crystallinity.

[0028] Figure 3 a, b, c, d are the atomic force microscope (AFM) measurement results of the ZIS-4TU, ZIS-8TU, ZIS-12TU, and ZIS-16TU nanosheets prepared in Examples 1, 2, 3, and 4 of the present invention, respectively. The corresponding layer thicknesses of the ZIS-4TU, ZIS-8TU, ZIS-12TU, and ZIS-16TU nanosheets are 44.8 nm, 18.6 nm, 11.5 nm, and 4 nm, respectively.

[0029] Figure 4 a is the ZnIn with different precursor ratios prepared in Examples 1, 2, 3, and 4 of the present invention. 2 S 4 UV-visible diffuse reflectance spectrum of the nanosheets. The upper right inset is its band gap diagram. From ZIS-16TU, ZIS-12TU, ZIS-8TU to ZIS-4TU, the cut-off absorption edge gradually redshifts. As the number of layers decreases, ZnIn 2 S 4 The optical band gap gradually increases from 2.39 eV to 2.77 eV, which should be attributed to the change of charge distribution caused by the interlayer van der Waals interaction.

[0030] Figure 4 b is the ZnIn with different precursor ratios prepared in Examples 1, 2, 3, and 4 of the present invention. 2 S 4 Photoluminescence (PL) spectrum of the nanosheets, with an excitation wavelength of 440 nm. From ZIS-16TU, ZIS-12TU, ZIS-8TU to ZIS-4TU, the PL peak gradually red shifts, further confirming that with the increase of ZnIn 2 S 4 The increase of atomic layer stacking leads to the decrease of direct band gap.

[0031] Figure 5 The present invention is based on ZnIn 2 S 4Schematic diagram of the working mechanism of the PEC photodetector. The figure includes a xenon lamp, an electrochemical workstation, an electrolyte tank, a working electrode, a counter electrode, and a reference electrode. 2 S 4 The Fermi level (E F ) and the electrolyte redox potential (hydrogen evolution potential: H + / H 2 , oxygen production potential: O 2 / H 2 O) is different, when ZnIn 2 S 4 When the working electrode and the electrolyte come into contact, a built-in electric field is formed at the interface. (CB: conduction band, VB: valence band) When light shines on the working electrode, electron-hole pairs are generated. Then, photoelectrons are generated from ZnIn 2 S 4 Flow to FTO and enter the external circuit. Photogenerated holes are transferred to ZnIn 2 S 4 / electrolyte interface is － The photogenerated electrons reach the counter electrode (Pt) and react with the free radicals OH* to form OH - , so far the entire circuit reflux is completed and self-powered. 2 S 4 Compared with other materials, PEC photodetectors have the advantages of excellent photoelectric properties, fast response and low dark current. 2 S 4 These advantages enable the PEC photodetector to realize self-powered function, which is in line with the development trend of low energy consumption. The more common application scenarios of PEC photodetectors are highly integrated broadband light detection and deep ultraviolet light detection for underwater optical communications. 2 S 4 The layer-band structure provides an opportunity to integrate both applications into one semiconductor.

[0032] Figure 6 The ZnIn prepared in Examples 1, 2, 3, and 4 of the present invention with different precursor ratios 2 S 4 The photoelectric characteristics of the nanosheets. 2 S 4 It has high photocurrent density and excellent transient photoresponse at any bias voltage. With the increase of layer number and the decrease of optical band gap, ZnIn2 S 4 The long wavelength of sunlight can be effectively utilized. The maximum photocurrent of ZIS-4TU reaches 2.5 mA cm at 0.6 V vs. Ag / AgCl. -2 .

[0033] Figure 7 The ZnIn prepared in Examples 1, 2, 3, and 4 of the present invention with different precursor ratios 2 S 4 Response time curve of the nanosheet under zero bias (0V (vs.Ag / AgCl)). The rise (decay) time is the response time for the photocurrent to change from 10% (90%) to 90% (10%). 2 S 4 The rise time and decay time are both within tens of milliseconds. The rise / decay time of ZIS-4TU under 450nm illumination is 12.5ms / 5.3ms, the rise / decay time of ZIS-8TU under 450nm illumination is 14.9ms / 8.2ms, the rise / decay time of ZIS-12TU under 355nm illumination is 11.7ms / 6.7ms, and the rise / decay time of ZIS-16TU under 355nm illumination is 23.3ms / 10ms, showing fast light response under both visible light and ultraviolet light.

[0034] Figure 8 a and b are ZnIn with different precursor ratios prepared in Examples 1, 2, 3 and 4 of the present invention. 2 S 4 Transient photoresponse behavior of the nanosheet at different wavelengths (254nm-650nm). Figure 8 0.0025 mA cm in a and b -2 , 0.1mA cm -2 , 0.05mA cm -2 , 0.001mA cm -2 The ruler on their left represents the scale of the layer. 2 S 4 The photodetectors all exhibited fast and stable transient photoresponses without external bias, demonstrating their potential as self-powered photodetection devices. ZIS-4TU had the largest Iph in the full optical range of 355-650nm, with the potential to further broaden the detection range, while ZIS-16TU exhibited the best photoresponse at 254nm, the visible light response at 450-650nm was successfully suppressed, and UV detection was optimized.

[0035] Figure 8 c and d are ZnIn with different precursor ratios prepared in Examples 1, 2, 3 and 4 of the present invention.2 S 4 The responsivity and detectivity of the nanosheet. ZIS-4TU has a high Rph (responsivity) from deep ultraviolet light to red light, with a maximum Rph of 90.29 mA W at 355 nm. -1 , demonstrating its potential in broadband light detection. However, ZIS-16TU only exhibits superior Rph in the UV band, reaching 90.13 mA W at 254 nm. -1 The best Rph of all these ZnIn 2 S 4 The photodetector exhibits excellent specific detection capability at different wavelengths, up to 1.602×10 12 Jones.

[0036] Fig. 9 a and b are the transient light response behaviors of the ZIS-4TU photodetector prepared in Example 1 of the present invention at different light powers at wavelengths of 254-765nm. ZIS-4TU has excellent transient light response from 254nm deep ultraviolet to 765nm near infrared, and the response intensity increases continuously with the increase of power density, and the detection range can achieve a wide spectrum detection effect.

[0037] Fig.10 This is the transient light response behavior of the ZIS-16TU photodetector prepared in Example 4 of the present invention at different light powers at wavelengths of 254-650nm. The light response in the visible light band is successfully suppressed, while the light response in the ultraviolet band gradually increases with the increase of power density. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. In the present invention, unless otherwise specified, the raw materials and equipment used can be purchased from the market or are commonly used in the art. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0039] Example 1 Two-dimensional rhombohedral phase ZnIn 2 S 4 Preparation method of nanosheet array photoanode

[0040] (1) The conductive glass FTO was ultrasonically cleaned with acetone, anhydrous ethanol, deionized water, and anhydrous ethanol for 15 minutes in sequence. After cleaning, the FTO was placed in the air to dry naturally.

[0041] (2) Weigh 34.8 mg ZnCl 2 、148mg InCl 3·4H 2 O and 76.9 mg CH 4 N 2 The S powder was placed in a beaker, 18 mL (18 g) of deionized water was added, and magnetic stirring was used to obtain a completely dissolved uniform precursor solution.

[0042] (3) Stick a high temperature resistant tape on one end of the conductive surface of the conductive glass FTO in step (1) to keep the conductive surface 1 cm 2 , keep 1cm 2 The purpose is to 2 S 4 When growing, it only grows to 1cm 2 area, so that it is easy to calculate when doing performance testing. Then, the conductive surface is facing up and placed in a plasma cleaning machine for treatment. The plasma treatment power is 60W and the time is 120s. The purpose of the conductive surface facing up is to make it face the direction of plasma emission. Within the effective time of 10 minutes, the two pieces of FTO are placed in a V-shaped polytetrafluoroethylene liner with the conductive surface facing down, and the precursor solution prepared in step (2) is added. Place it in a forced air drying oven and heat it at 170°C for 12 hours. After the reaction is completed, take out the sample and repeatedly rinse the surface impurities with deionized water and anhydrous ethanol to obtain ZnIn 2 S 4 The photoanode sample was labeled as ZIS-4TU.

[0043] (4) The ZIS-4TU nanosheets grown on the FTO surface were peeled off into ethanol and ultrasonicated in an ultrasonic cleaner for 30 min. The solution was then diluted with ethanol to a slightly yellow color. A small amount of the solution was dripped onto a silicon wafer and allowed to dry at room temperature. The thickness of a single ZIS-4TU nanosheet on the silicon wafer was measured using an atomic force microscope.

[0044] (5) The light absorption performance of the ZIS-4TU photoanode was characterized by using a UV-visible spectrophotometer. The ZIS-4TU photoanode grown on FTO glass was directly embedded in BaSO 4 The background white plate is uniformly embedded in BaSO 4 The sample with a flat surface in the background white board is tested, the test range is 200-800nm, and the spectral bandwidth is 5nm.

[0045] (6) The optical properties of the ZIS-4TU photoanode were characterized by photoluminescence spectroscopy. The ZIS-4TU photoanode grown on FTO glass was directly used for testing with an excitation wavelength of 440 nm and a test range of 460 nm-640 nm.

[0046] (7) The photoelectrochemical and photodetection performances of the ZIS-4TU photoanode were tested using a three-electrode system. The ZIS-4TU photoanode was used as the working electrode, the Pt electrode was used as the counter electrode, the Ag / AgCl electrode was used as the reference electrode, and the electrolyte was 0.5 M Na 2 SO 4 With 0.2MNa 2 SO 3 A mixed aqueous solution (pH = 9.6) was prepared using an AM 1.5G xenon lamp to simulate sunlight with an intensity of approximately 100 mW / cm 2 The potential test range of the linear voltammetric characteristic curve (LSV) is -0.8~0.6V (vs.Ag / AgCl), and the voltage scanning rate is 3mV / s. The photoelectric performance at different wavelengths uses a 254nm deep ultraviolet LED lamp and 355nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm and 765nm filters. The power size is divided into five energy levels: Ⅰ, Ⅱ, Ⅲ, Ⅳ, and Ⅴ. The cycle of the transient light response test is 10s (5s irradiation, 5s dark).

[0047] Example 2 Two-dimensional rhombohedral phase ZnIn 2 S 4 Preparation method of nanosheet array photoanode

[0048] (1) The conductive glass FTO was ultrasonically cleaned with acetone, anhydrous ethanol, deionized water, and anhydrous ethanol for 15 minutes in sequence. After cleaning, the FTO was placed in the air to dry naturally.

[0049] (2) Weigh 34.8 mg ZnCl 2 、148mg InCl 3 ·4H 2 O and 153.8 mg CH 4 N 2 The S powder was placed in a beaker, 18 mL (18 g) of deionized water was added, and magnetic stirring was used to obtain a completely dissolved uniform precursor solution.

[0050] (3) Stick a high temperature resistant tape on one end of the conductive surface of the conductive glass FTO in step (1) to keep the conductive surface 1 cm 2 , then placed in a plasma cleaning machine with the conductive surface facing up, the plasma treatment power is 60W, the time is 120s, and within the effective time of 10min, the two FTO sheets are placed in a polytetrafluoroethylene liner in a V-shaped conductive surface facing down, and the precursor solution prepared in step (2) is added. Place in a blast drying oven and heat at 170°C for 12h. After the reaction is completed, take out the sample and repeatedly rinse the surface impurities with deionized water and anhydrous ethanol to obtain ZnIn 2 S 4The photoanode sample was labeled as ZIS-8TU.

[0051] (4) The ZIS-8TU nanosheets grown on the FTO surface were peeled off into ethanol and ultrasonicated in an ultrasonic cleaner for 30 min. The solution was then diluted with ethanol to a slightly yellow color. A small amount of the solution was dripped onto a silicon wafer and allowed to dry at room temperature. The thickness of a single ZIS-8TU nanosheet on the silicon wafer was measured using an atomic force microscope.

[0052] (5) The light absorption performance of the ZIS-8TU photoanode was characterized by using a UV-visible spectrophotometer. The ZIS-8TU photoanode grown on FTO glass was directly embedded in BaSO 4 The background white plate is uniformly embedded in BaSO 4 The sample with a flat surface in the background white board is tested, the test range is 200-800nm, and the spectral bandwidth is 5nm.

[0053] (6) The optical properties of the ZIS-8TU photoanode were characterized by photoluminescence spectroscopy. The ZIS-8TU photoanode grown on FTO glass was directly used for testing with an excitation wavelength of 440 nm and a test range of 460 nm-640 nm.

[0054] (7) The photoelectrochemical and photodetection performances of the ZIS-8TU photoanode were tested using a three-electrode system. The ZIS-8TU photoanode was used as the working electrode, the Pt electrode was used as the counter electrode, the Ag / AgCl electrode was used as the reference electrode, and the electrolyte was 0.5 M Na 2 SO 4 With 0.2MNa 2 SO 3 A mixed aqueous solution (pH = 9.6) was prepared using an AM1.5G xenon lamp to simulate sunlight with an intensity of approximately 100 mW / cm 2 The potential test range of the linear voltammetric characteristic curve (LSV) is -0.8~0.6V (vs.Ag / AgCl) and the voltage scanning rate is 3mV / s. The photoelectric performance at different wavelengths uses a 254nm deep ultraviolet LED lamp and 355nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm and 765nm filters. The power is divided into five energy levels: Ⅰ, Ⅱ, Ⅲ, Ⅳ, and Ⅴ. The cycle of the transient light response test is 10s (5s irradiation, 5s dark).

[0055] Example 3 Two-dimensional rhombohedral phase ZnIn 2 S 4 Preparation method of nanosheet array photoanode

[0056] (1) The conductive glass FTO was ultrasonically cleaned with acetone, anhydrous ethanol, deionized water, and anhydrous ethanol for 15 minutes in sequence. After cleaning, the FTO was placed in the air to dry naturally.

[0057] (2) Weigh 34.8 mg ZnCl 2 、148mg InCl 3 ·4H 2 O and 230.7 mg CH 4 N 2 The S powder was placed in a beaker, 18 mL (18 g) of deionized water was added, and magnetic stirring was used to obtain a completely dissolved uniform precursor solution.

[0058] (3) Stick a high temperature resistant tape on one end of the conductive surface of the conductive glass FTO in step (1) to keep the conductive surface 1 cm 2 , then placed in a plasma cleaning machine with the conductive surface facing up, the plasma treatment power is 60W, the time is 120s, and within the effective time of 10min, the two FTO sheets are placed in a polytetrafluoroethylene liner in a V-shaped conductive surface facing down, and the precursor solution prepared in step (2) is added. Place in a blast drying oven and heat at 170°C for 12h. After the reaction is completed, take out the sample and repeatedly rinse the surface impurities with deionized water and anhydrous ethanol to obtain ZnIn 2 S 4 The photoanode sample was labeled as ZIS-12TU.

[0059] (4) The ZIS-12TU nanosheets grown on the FTO surface were peeled off into ethanol and ultrasonicated in an ultrasonic cleaner for 30 min. The solution was then diluted with ethanol to a slightly yellow color. A small amount of the solution was dripped onto a silicon wafer and allowed to dry at room temperature. The layer thickness of a single ZIS-12TU nanosheet on the silicon wafer was measured using an atomic force microscope.

[0060] (5) The light absorption performance of the ZIS-12TU photoanode was characterized by using a UV-visible spectrophotometer. The ZIS-12TU photoanode grown on FTO glass was directly embedded in BaSO 4 The background white plate is uniformly embedded in BaSO 4 The sample with a flat surface in the background white board is tested, the test range is 200-800nm, and the spectral bandwidth is 5nm.

[0061] (6) The optical properties of the ZIS-12TU photoanode were characterized by photoluminescence spectroscopy. The ZIS-12TU photoanode grown on FTO glass was directly tested with an excitation wavelength of 440 nm and a test range of 460 nm-640 nm.

[0062] (7) The photoelectrochemical and photodetection performances of the ZIS-12TU photoanode were tested using a three-electrode system. The ZIS-12TU photoanode was used as the working electrode, the Pt electrode was used as the counter electrode, the Ag / AgCl electrode was used as the reference electrode, and the electrolyte was 0.5 M Na 2 SO 4 With 0.2M Na 2 SO 3 A mixed aqueous solution (pH = 9.6) was prepared using an AM1.5G xenon lamp to simulate sunlight with an intensity of approximately 100 mW / cm 2 The potential test range of the linear voltammetric characteristic curve (LSV) is -0.8~0.6V (vs.Ag / AgCl), and the voltage scanning rate is 3mV / s. The photoelectric performance at different wavelengths uses a 254nm deep ultraviolet LED lamp and 355nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm and 765nm filters. The power size is divided into five energy levels: Ⅰ, Ⅱ, Ⅲ, Ⅳ, and Ⅴ. The cycle of the transient light response test is 10s (5s irradiation, 5s dark).

[0063] Example 4 Two-dimensional rhombohedral phase ZnIn 2 S 4 Preparation method of nanosheet array photoanode

[0064] (1) The conductive glass FTO was ultrasonically cleaned with acetone, anhydrous ethanol, deionized water, and anhydrous ethanol for 15 minutes in sequence. After cleaning, the FTO was placed in the air to dry naturally.

[0065] (2) Weigh 34.8 mg ZnCl 2 、148mg InCl 3 ·4H 2 O and 307.6 mg CH 4 N 2 The S powder was placed in a beaker, 18 mL (18 g) of deionized water was added, and magnetic stirring was used to obtain a completely dissolved uniform precursor solution.

[0066] (3) Stick a high temperature resistant tape on one end of the conductive surface of the conductive glass FTO in step (1) to keep the conductive surface 1 cm 2 , then placed in a plasma cleaning machine with the conductive surface facing up, the plasma treatment power is 60W, the time is 120s, and within the effective time of 10min, the two FTO sheets are placed in a polytetrafluoroethylene liner in a V-shaped conductive surface facing down, and the precursor solution prepared in step (2) is added. Place in a blast drying oven and heat at 170°C for 12h. After the reaction is completed, take out the sample and repeatedly rinse the surface impurities with deionized water and anhydrous ethanol to obtain ZnIn 2 S 4The photoanode sample was labeled as ZIS-16TU.

[0067] (4) The ZIS-16TU nanosheets grown on the FTO surface were peeled off into ethanol and ultrasonicated in an ultrasonic cleaner for 30 min. The solution was then diluted with ethanol to a slightly yellow color. A small amount of the solution was dripped onto a silicon wafer and allowed to dry at room temperature. The thickness of a single ZIS-16TU nanosheet on the silicon wafer was measured using an atomic force microscope.

[0068] (5) The light absorption performance of the ZIS-16TU photoanode was characterized by using a UV-visible spectrophotometer. The ZIS-16TU photoanode grown on FTO glass was directly embedded in BaSO 4 The background white plate is uniformly embedded in BaSO 4 The sample with a flat surface in the background white board is tested, the test range is 200-800nm, and the spectral bandwidth is 5nm.

[0069] (6) The optical properties of the ZIS-16TU photoanode were characterized by photoluminescence spectroscopy. The ZIS-16TU photoanode grown on FTO glass was directly tested with an excitation wavelength of 440 nm and a test range of 460 nm-640 nm.

[0070] (7) The photoelectrochemical and photodetection performances of the ZIS-16TU photoanode were tested using a three-electrode system. The ZIS-16TU photoanode was used as the working electrode, the Pt electrode was used as the counter electrode, the Ag / AgCl electrode was used as the reference electrode, and the electrolyte was 0.5 M Na 2 SO 4 With 0.2M Na 2 SO 3 A mixed aqueous solution (pH = 9.6) was prepared using an AM 1.5G xenon lamp to simulate sunlight with an intensity of approximately 100 mW / cm 2 The potential test range of the linear voltammetric characteristic curve (LSV) is -0.8~0.6V (vs.Ag / AgCl), and the voltage scanning rate is 3mV / s. The photoelectric performance at different wavelengths uses a 254nm deep ultraviolet LED lamp and 355nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm and 765nm filters. The power size is divided into five energy levels: Ⅰ, Ⅱ, Ⅲ, Ⅳ, and Ⅴ. The cycle of the transient light response test is 10s (5s irradiation, 5s dark).

[0071] The following table shows the optical power values ​​of five energy levels I, II, III, IV, and V corresponding to wavelengths of 254nm, 355nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm, and 765nm in the present invention.

[0072]

[0073] In this paper, we developed a simple method to tune the rhombohedral phase ZnIn 2 S 4 By adjusting the concentration of thiourea in the precursor solution, the threshold growth was achieved, so that the rhombohedral phase ZnIn 2 S 4 The nanosheets achieve controllable regulation of the number of atomic layers. Thiourea can be used as an effective stabilizer to stabilize the formation of nanosheets. However, when thiourea is present in excess, the excess thiourea adsorbs on the surface of the native nanocrystals, partially hindering the growth of oriented crystals. This leads to the inhibition of growth along the c-axis direction, which in turn leads to the limitation of the stacking of atomic layers. This forms a rhombohedral phase ZnIn with fewer layers. 2 S 4 Nanosheets.

[0074] Example 5 Two-dimensional rhombohedral phase ZnIn 2 S 4 Applications of Nanosheet Array Photoanodes

[0075] The following steps are involved:

[0076] Constructing a PEC-type self-powered photodetector using the two-dimensional rhombohedral phase ZnIn 2 S 4 Nanosheet array photoanode as the working electrode of PEC-type self-powered photodetector;

[0077] The PEC type self-powered photoelectric detector also includes an electrochemical workstation, an electrolyte tank, a reference electrode and a counter electrode; an electrolyte is provided in the electrolyte tank, and the reference electrode, the working electrode and the counter electrode are suspended in the electrolyte tank, all in contact with the electrolyte and not in contact with the bottom of the electrolyte tank; the fixed ends of the reference electrode, the working electrode and the counter electrode are fixed to the cover of the electrolyte tank through the card hole, and the three electrodes are freely suspended in the electrolyte tank, about 2-3 cm away from the bottom of the electrolyte tank, so that the photoelectrochemical reaction is more sufficient.

[0078] The connection of the external circuit in the PEC type self-powered photoelectric detector includes connecting the working electrode to the positive pole of the electrochemical workstation power supply with a green electrode line; connecting the counter electrode to the negative pole of the electrochemical workstation power supply with a red electrode line; and connecting the reference electrode to the reference potentiometer with a white electrode line.

[0079] The above descriptions are only some specific implementation methods of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any person familiar with the art within the technical scope disclosed in the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a two-dimensional rhombohedral phase ZnIn2S4 nanosheet array photoanode, characterized in that: The following steps are involved: (1) Obtain clean conductive glass FTO; (2) mixing the following raw materials according to a preset ratio: ZnCl2, InCl3·4H2O and CH4N2S, and dissolving them in water to obtain a precursor solution; (3) subjecting the conductive glass FTO conductive surface described in step (1) to plasma surface treatment; Within the effective time after the plasma surface treatment, two FTO sheets are placed in a reaction container in a "V" shape with the conductive surface facing downward, and the precursor solution prepared in step (2) is added to perform a hydrothermal reaction, thereby obtaining a two-dimensional rhombus phase ZnIn2S4 nanosheet array on the conductive surface of the conductive glass FTO; Conductive glass FTO and the conductive surface of the conductive glass FTO are used together to obtain a two-dimensional rhombus phase ZnIn2S4 nanosheet array, which are used as a photoanode to make a working electrode of a PEC type self-powered photodetector; the prepared two-dimensional rhombus phase ZnIn2S4 nanosheet array photoanode includes: conductive glass FTO and a two-dimensional rhombus phase ZnIn2S4 nanosheet array in-situ grown on the conductive surface of the conductive glass FTO; the two-dimensional rhombus phase ZnIn2S4 nanosheet array is composed of two-dimensional rhombus phase ZnIn2S4 nanosheets stacked; In step (2), the setting of the preset ratio includes the following steps: Obtaining the wavelength range of the detection target of the PEC type self-powered photoelectric detector; setting the preset ratio according to the wavelength range of the detection target; The wavelength range of the detection target is 355-765 nm, and the preset molar ratio of ZnCl2, InCl3·4H2O and CH4N2S is: 1:2:4; The layer thickness of the two-dimensional rhombohedral phase ZnIn2S4 nanosheet is 44.8 nm; Or the wavelength range of the detection target is 254-355nm, the preset molar ratio of ZnCl2, InCl3·4H2O and CH4N2S is: 1:2:16, and the layer thickness of the two-dimensional rhombus phase ZnIn2S4 nanosheet is 4nm.

2. The method for preparing a two-dimensional rhombohedral phase ZnIn2S4 nanosheet array photoanode according to claim 1, characterized in that: In step (3), The reaction container is a polytetrafluoroethylene liner; the hydrothermal reaction specifically comprises: placing the polytetrafluoroethylene liner in a high-pressure reactor and performing a hydrothermal reaction at a temperature of 170° C. for 12 hours; The plasma treatment specifically includes the following steps: treating in a plasma cleaning machine with a power of 60 W and a time of 120 s; The effective time refers to the time after the plasma treatment when the conductive glass FTO surface has energy, which can promote the growth of compounds on the FTO surface. The effective time is 10 minutes.

3. Photoelectric detection application of the two-dimensional rhombus phase ZnIn2S4 nanosheet array photoanode prepared by the preparation method as described in any one of claims 1 to 2, characterized in that: The following steps are involved: Constructing a PEC type self-powered photodetector, using the two-dimensional rhombus phase ZnIn2S4 nanosheet array photoanode as a working electrode of the PEC type self-powered photodetector; The PEC type self-powered photoelectric detector also includes an electrochemical workstation, an electrolyte tank, a reference electrode and a counter electrode; an electrolyte is provided in the electrolyte tank, and the reference electrode, the working electrode and the counter electrode are suspended in the electrolyte tank, all in contact with the electrolyte, and none of them touch the bottom of the electrolyte tank; The working electrode is connected to the positive pole of the power supply of the electrochemical workstation, the counter electrode is connected to the negative pole of the power supply of the electrochemical workstation, and the reference electrode is connected to the reference potentiometer of the electrochemical workstation.

4. The photoelectric detection application according to claim 3, characterized in that: The electrolyte in the electrolyte solution is 0.5M Na2SO4 and 0.2M Na2SO3; the reference electrode is an Ag / AgCl electrode; and the counter electrode is a Pt electrode.

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