Polarization electric field enhanced mole-level hydrogen production photocatalyst, preparation method and application

Abstract

The present application relates to the technical field of photocatalytic material, and particularly relates to a polarization electric field enhanced molar hydrogen production photocatalyst, a preparation method and application, and its technical points are: through simple and easy to operate physical adsorption method and calcination method, the electronegativity Pt-P3 monatomic group is dispersed on the surface of dendritic CdS to construct PtP3@PEF / CdS, the polarization electric field (PEF) is formed in the CdS to resist the effect of coulomb electric field, the dosage of Pt is reduced, the atomic utilization rate is improved, the active site is fully exposed, the hydrogen overpotential of the semiconductor is reduced, the conductivity of the semiconductor system is improved, the migration distance of photoinduced electron-hole is shortened, and a flat plate square meter level photovoltaic hydrogen production device is also built, the PtP3@PEF / CdS is coated on the flat plate square meter level photovoltaic hydrogen production device, the molar photovoltaic hydrogen production rate is first achieved, and the transformation from laboratory research to industrial pilot stage is realized.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic materials technology, specifically to a polarized electric field-enhanced molar-level hydrogen production photocatalyst, its preparation method, and its application. Background Technology

[0002] With increasingly severe energy and environmental problems, the development of clean and renewable energy sources is urgently needed. Hydrogen, due to its abundant sources, high calorific value, low density, lack of pollution, and storability, has been identified as a strategic new energy source. Among the many hydrogen production methods, unlike water electrolysis which consumes a large amount of electricity, the solar photocatalytic water splitting technology developed in recent years only requires solar energy to decompose water and obtain hydrogen, making it a truly green hydrogen production method. Semiconductor photocatalysts are crucial for converting solar energy into hydrogen energy, and CdS, due to its suitable band structure and conduction band potential, is considered a highly promising photocatalyst. However, due to Coulomb forces, electrons and holes generated by photoexcitation in CdS are prone to recombination, resulting in low photoelectric conversion efficiency; furthermore, sulfides generally suffer from photocorrosion problems, leading to insufficient stability. To overcome the aforementioned drawbacks, current research has found that hydrogen production co-catalysts supported with noble metals such as Pt, Au, and Ag can effectively alleviate these problems. These co-catalysts can reduce the hydrogen production overpotential, improve conductivity, and act as electron traps to suppress carrier recombination. However, traditional nanoparticle morphologies require a large amount of noble metals, resulting in high costs and extremely low atom utilization. In recent years, it has been discovered that metal single-atom (MSA) catalysts can maximize the exposure of active sites, achieving 100% atom utilization. In photocatalysis, they can serve as co-catalysts to improve conductivity, regulate the light absorption performance of semiconductors, and act as active sites to promote proton reduction reactions on the surface.

[0003] Chinese patent CN201910706168.7 discloses a novel single-atom photocatalyst for hydrogen production. This catalyst has an ultrathin porous sheet-like structure and achieves in-situ reduction of Pt single atoms through abundant groups on the surface of carbon dots (CDs), yielding the catalyst CdS@CDs / Pt-SAs, which can improve hydrogen production efficiency to 45.5 mmol / h. -1 g -1 Chinese patent CN202110752625.3 discloses a photocatalyst for graphitic carbon nitride supported on a single atom of noble metal Pd, which exhibits better photocatalytic performance compared to pure graphitic carbon nitride and graphitic carbon nitride supported on Pd nanoparticles. Chinese patent CN202210136577.X discloses a method for preparing a photocatalyst for single-atom Pt embedded in a covalent organic framework, yielding a Pt1@TpPa-1-COF photocatalyst with a hydrogen production efficiency of 719 µmol g. -1 h -1Tests show that the single-atom Pt-intercalated TpPa-1-COF material provides a large number of Pt active sites, which provides favorable conditions for catalytic hydrogen production from water.

[0004] However, the hydrogen production rates of photocatalysts constructed using the above methods are still relatively low, with almost no studies reaching the molar scale, far from meeting the needs of industrial mass production. Moreover, the design of single-atom systems also has the following problems: due to the high surface energy of single atoms, they are prone to aggregation or changes in valence state, resulting in unstable performance; commonly used coordinating atoms such as O, N, and S tend to lead to high oxidation states or high coordination numbers of single atoms, reducing catalytic activity.

[0005] Therefore, developing a photocatalyst capable of achieving molar-level hydrogen production rates with stable and highly active coordination, and transforming laboratory research on photocatalytic water splitting for hydrogen production into industrial-scale experiments, are urgent technical challenges to be solved in this field. Summary of the Invention

[0006] To address the aforementioned shortcomings of existing technologies, this invention provides a polarized electric field-enhanced molar-scale hydrogen production photocatalyst, its preparation method, and its application. This effectively solves the problems of single-atom catalysts being prone to aggregation and having low activity due to poor coordination environment, severe recombination of CdS photogenerated carriers leading to low hydrogen production rates, and the lack of square meter-scale hydrogen production devices in existing technologies.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] In a first aspect, the present invention provides a molar-scale hydrogen production photocatalyst with enhanced polarization electric field. The photocatalyst is PtP3@PEF / CdS, comprising a CdS support and a Pt-P3 single-atom group supported thereon. The Pt-P3 single-atom group has an electron-withdrawing function. The photocatalyst PtP3@PEF / CdS is used to achieve a molar-scale photocatalytic water splitting hydrogen production rate.

[0009] In this structure, Pt atoms are anchored by three P atoms to form a stable Pt-P3 coordination structure, thereby generating a polarization electric field PEF on the CdS surface that is opposite to the direction of the internal Coulomb electric field.

[0010] Furthermore, the Pt atoms are atomically dispersed with 100% atomic utilization, and each Pt atom serves as a hydrogen-producing active site.

[0011] In a second aspect, the present invention also provides a method for preparing a molar-scale hydrogen production photocatalyst with enhanced polarization electric field, the method being used to prepare the molar-scale hydrogen production photocatalyst with enhanced polarization electric field described in the first aspect, comprising the following steps:

[0012] S1. Dissolve the cadmium source and the sulfur source in deionized water to form solution A and solution B respectively. Mix solution A and solution B, add strong acid, and stir to form a suspension.

[0013] S2. The suspension is heated and kept at a constant temperature for reaction, then cooled, centrifuged, washed and dried to obtain CdS catalyst powder;

[0014] S3. The CdS catalyst powder is ultrasonically dispersed in a platinum salt solution, stirred, and then dried.

[0015] S4. The dried product obtained in step S3 is mixed and ground with a phosphorus source, calcined under an inert atmosphere, and then cooled and ground to obtain PtP3@PEF / CdS photocatalyst.

[0016] Furthermore, in step S1, the cadmium source is selected from at least one of cadmium chloride, cadmium nitrate, cadmium sulfate, or cadmium acetate;

[0017] The sulfur source is selected from at least one of thiourea, sodium sulfide, sodium thiosulfate, or urea.

[0018] The strong acid is selected from at least one of hydrofluoric acid, hydrobromic acid, hydrochloric acid, nitric acid, or sulfuric acid.

[0019] Furthermore, in step S1, the amount of cadmium source used is 4.0-6.0 mmol, the amount of sulfur source used is 4.0-6.0 mmol, the amount of deionized water used is 10-30 ml, and the amount of strong acid used is 0.5-1.5 ml.

[0020] The stirring time is 2-4 hours.

[0021] Furthermore, in step S2, the suspension is heated to 160-200°C, and the reaction time is 15-24 h.

[0022] Furthermore, in step S2, the washing operation is performed using deionized water and ethanol, and the number of washing cycles is 1-4; the drying temperature is 60-110℃, and the drying time is 6-10 h.

[0023] Furthermore, in step S3, the platinum salt is selected from at least one of chloroplatinic acid, platinum nitrate, platinum sulfate, or platinum chloride, with a solution concentration of 0.05-0.15 mmol / L, a drying temperature of 60-100℃, and a drying time of 15-20 h.

[0024] Furthermore, in step S3, the stirring time is 1-5 hours.

[0025] Furthermore, in step S4, the calcination temperature is 200-400℃, the calcination time is 10-50 min, and the heating rate is 2-8℃ / min.

[0026] The phosphorus source is selected from at least one of sodium hypophosphite, disodium hydrogen phosphate, potassium dihydrogen phosphate, or sodium monohydrogen phosphate.

[0027] Furthermore, the inert atmosphere is an argon or nitrogen atmosphere.

[0028] Thirdly, the present invention also provides the application of a polarization-enhanced molar-scale hydrogen production photocatalyst in the catalytic splitting of water to produce hydrogen, wherein the photocatalyst is prepared according to the preparation method described in the second aspect.

[0029] Furthermore, the application is to use the photocatalyst to catalytically decompose water to produce hydrogen in a flat-panel, square-scale photovoltaic hydrogen production device. The device includes a reaction module, a liquid driving module, a gas-liquid separation module, and a detection and control module, wherein the photocatalyst is coated onto the conductive glass carrier of the device by an adhesive.

[0030] The reaction module has a light-transmitting window and a catalyst support. The light-transmitting window is made of ITO glass, and the catalyst support is made of FTO glass. Liquid and gas flow channels are constructed inside.

[0031] The liquid drive module is used to circulate the reaction solution, ensuring that the solution is in full contact with the catalyst.

[0032] The gas-liquid separation module is used to separate the generated hydrogen gas;

[0033] The detection and control module is used for online detection and measurement of gas production.

[0034] Furthermore, the adhesive is PVDF or DMF.

[0035] The technical solution provided by this invention has the following advantages compared with the known prior art:

[0036] 1. The PtP3@PEF / CdS photocatalyst provided by this invention disperses electronegative Pt-P3 single-atom groups on the surface of dendritic CdS through a simple and easy-to-operate physical adsorption and calcination method to construct PtP3@PEF / CdS. A polarized electric field (PEF) is formed inside CdS to counteract the effect of the Coulomb electric field, thereby reducing the amount of Pt used, improving the atomic utilization rate, fully exposing active sites, reducing the hydrogen production overpotential of the semiconductor, improving the conductivity of the semiconductor system, and shortening the migration distance of photogenerated electrons and holes. For the first time, a photovoltaic hydrogen production rate on the molar scale has been achieved, realizing a huge leap from the traditional millimolecular level to the molar level in the photocatalytic water splitting hydrogen production rate, and realizing the transformation from laboratory research to the industrial pilot stage.

[0037] 2. This invention uses three P atoms with moderate electronegativity to anchor one Pt atom, forming an extremely stable Pt-P3 triangular coordination structure. This structure effectively avoids the problem of high oxidation state or high coordination number of metal single atoms caused by conventional high electronegativity coordination atoms such as O, N, and S, thereby significantly improving the intrinsic activity and long-term stability of the catalytic center.

[0038] 3. The Pt-P3 group loaded on the CdS surface of the present invention has a strong electron-withdrawing effect, which can drive photogenerated electrons to migrate rapidly from the CdS support to it. At the same time, the polarization electric field induced by this group, which is opposite to the Coulomb electric field inside CdS, works together to greatly suppress the recombination of photogenerated electron-hole pairs, providing a sufficient charge source for efficient hydrogen production.

[0039] 4. The Pt atoms of the present invention are dispersed at the atomic level, achieving 100% atomic utilization, so that each noble metal Pt atom becomes an effective hydrogen production active site. While ensuring a catalytic efficiency far exceeding that of Pt nanoparticles, the amount of noble metal used is greatly reduced, and the cost is significantly saved.

[0040] 5. The flat-plate, square-scale photovoltaic hydrogen production device provided by this invention solves the problems of mass transfer, heat transfer and product release in the scale-up process through the synergy of reaction, liquid drive and gas-liquid separation modules, providing an ideal platform for high-performance catalysts to exert their effectiveness, and enabling molar-level hydrogen production rates to be achieved on a square-scale scale. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0042] Figure 1 This is a schematic diagram of the preparation technology route of the photocatalyst of the present invention;

[0043] Figure 2 This is a schematic diagram of the design principle of the pilot-scale flat-plate photovoltaic hydrogen production reactor of the present invention;

[0044] Figure 3 This is a diagram of a pilot-scale flat-plate photovoltaic hydrogen production reactor prepared by spin coating method according to the present invention;

[0045] Figure 4 The XRD patterns of CdS, Pt / CdS, P / CdS and PtP3@PEF / CdS of this invention are shown below.

[0046] Figure 5 The images show SEM images of CdS and PtP3@PEF / CdS from this invention.

[0047] Figure 6 XPS spectrum of PtP3@PEF / CdS in this invention;

[0048] Figure 7 This is the charge density difference diagram of the PtP3@PEF / CdS system obtained by theoretical calculation in this invention;

[0049] Figure 8 The UV-Vis absorption spectra of CdS and PtP3@PEF / CdS in this invention are shown.

[0050] Figure 9 The fluorescence spectra of CdS and PtP3@PEF / CdS in this invention are shown.

[0051] Figure 10 The transient fluorescence spectra and carrier lifetime analysis diagrams of CdS and PtP3@PEF / CdS of this invention are shown below.

[0052] Figure 11 This is a graph showing the photocatalytic hydrogen production activity of different control samples in this invention. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0054] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated herein by reference to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail. The terms “comprising,” “including,” “having,” “containing,” etc., as used herein are open-ended terms, meaning that they include but are not limited to. Unless the context clearly indicates otherwise, the expressions “a” and “an” as used herein include plural references. It should be noted that “first,” “second,” etc., are used merely for convenience of description and distinction and should not be construed as indicating or implying relative importance. The term “about” as used herein indicates a range of ±20% of the following numerical value. In some embodiments, the term “about” indicates a range of ±10% of the following numerical value. In some embodiments, the term “about” indicates a range of ±5% of the following numerical value.

[0055] The present invention will be further described below with reference to embodiments.

[0056] This invention provides a polarization field-enhanced molar-scale hydrogen production photocatalyst, its preparation method, and its application. The photocatalyst is PtP3@PEF / CdS, comprising a CdS support and Pt-P3 single-atom groups supported thereon. The Pt-P3 single-atom groups have electron-withdrawing functionality. The PtP3@PEF / CdS photocatalyst is used to achieve molar-scale photocatalytic water splitting for hydrogen production. The Pt atoms are anchored by three P atoms, forming a stable Pt-P3 coordination structure, thereby generating a polarization field (PEF) on the CdS surface opposite to the internal Coulomb electric field. The Pt atoms are atomically dispersed, with 100% atomic utilization, and each Pt atom serves as a hydrogen production active site.

[0057] A detailed experimental procedure for preparing a polarization-enhanced molar-scale hydrogen production photocatalyst PtP3@PEF / CdS is provided below:

[0058] 1. Dissolve 4.0-6.0 mmol CdCl2·2.5H2O in 10-30 ml of deionized water and label it as solution A; dissolve 4.0-6.0 mmol thiourea in 10-30 ml of deionized water and label it as solution B.

[0059] 2. Add solution B dropwise to solution A while stirring to obtain a homogeneous mixed solution;

[0060] 3. Add 0.5-1.5 ml of hydrofluoric acid to the mixed solution obtained in step 2, and stir for 2-4 hours to ensure thorough mixing;

[0061] 4. Transfer the suspension obtained in step 3 to a polytetrafluoroethylene reactor, heat it from room temperature to 160-200℃ in a drying oven and keep it at that temperature for 15-24 hours. After the reaction is complete, allow it to cool naturally to room temperature.

[0062] 5. Centrifuge the product obtained in step 4, wash it with deionized water and ethanol 1-4 times until the supernatant is transparent, collect the precipitate, and finally dry the precipitate in a drying oven at 60-110℃ for 6-10 h, grind it thoroughly to obtain the CdS catalyst.

[0063] 6. Disperse 0.1-0.3 g of the CdS powder obtained in step 5 in ultrasonically into 10-50 ml of 0.05-0.15 mmol / L H2PtCl6 solution prepared in a volumetric flask, stir for 1-5 h, and then place in a drying oven at 60-100℃ for 15-20 h. Grind the dried solid thoroughly.

[0064] The powder obtained in step 6 is mixed and ground with 0.1-0.3 g of NaH2PO2, and then placed in a tube furnace for calcination under an inert atmosphere (argon, nitrogen). The temperature is increased to 200-400℃ at a rate of 2-8℃, and the calcination time is 10-50 min. After cooling to room temperature, it is ground to obtain the PtP3@PEF / CdS photocatalyst.

[0065] This invention also provides an application of a polarized electric field-enhanced molar-scale hydrogen production photocatalyst in catalytic water splitting for hydrogen production. This application involves using the photocatalyst in a flat-panel, square-scale photovoltaic hydrogen production device to catalytically split water for hydrogen production. The device includes a reaction module, a liquid-driven module, a gas-liquid separation module, and a detection and control module. The photocatalyst is coated onto a conductive glass carrier of the device using an adhesive. The reaction module has a light-transmitting window made of ITO glass and a catalyst carrier made of FTO glass, with internal liquid and gas flow channels. The liquid-driven module circulates the reaction solution, ensuring sufficient contact between the solution and the catalyst. The gas-liquid separation module separates the generated hydrogen gas. The detection and control module is used for online detection and metering of gas production.

[0066] Figure 1 The diagram illustrates the preparation route and planar coating schematic of the photocatalyst of this invention. As shown, the preparation of the main photocatalyst involves three stages: First, cadmium chloride and thiourea solution are mixed and reacted at 180°C for 20 hours to synthesize cadmium sulfide (CdS); second, hexachloroplatinic acid is loaded onto CdS to introduce platinum ions (Pt). 2+ ), forming Pt 2+-CdS intermediate; finally, the PtP3@PEF / CdS photocatalyst was obtained by heat treatment with sodium hypophosphite (NaH2PO2) at 300℃ for 30 minutes to reduce and introduce phosphorus. Therefore, this preparation method synthesizes a structurally stable single-atom photocatalyst using a simple and easy-to-operate physical adsorption and calcination method. The obtained photocatalyst was then mixed uniformly with PVDF and DMF, wherein the mass ratio of photocatalyst to PVDF was 6:1, and an appropriate amount of DMF was added to form a homogeneous mixture. The photocatalyst coating amount was 5 g / m³. 2 Spin-coating the FTO glass plate of the constructed flat-panel photovoltaic hydrogen production reactor is a simple and low-cost preparation method that is conducive to industrial application.

[0067] Figure 2 This diagram illustrates the design principle of a pilot-scale flat-plate photovoltaic hydrogen production reactor. It primarily consists of a reaction module, a liquid drive module, a gas-liquid separation module, and a detection and control module. Each module can be customized. The coordinated design of multiple modules meets the requirements for a square meter-scale reaction in the pilot-scale stage. The reactor features a built-in manual injection valve, allowing direct coupling with gas chromatography for online product detection. Gas can also be collected via gas bags or other gas collection devices. ITO glass with good light transmittance is used as the light window, and FTO glass with good conductivity is used as the carrier, providing a large light irradiation area. A liquid and gas flow channel is constructed within the sealed flat-plate glass reactor, facilitating water flow and hydrogen release. The liquid flow in the reaction system ensures sufficient contact between the reaction solution and the catalyst. Simultaneously, the gaseous products generated during the reaction are carried out of the reaction system by the flowing liquid. The generated gas enters a gas separation device for gas-liquid separation. The separated gas can be collected separately, and the yield of the gaseous products can be measured.

[0068] Figure 3 This diagram shows a pilot-scale flat-plate photovoltaic hydrogen production reactor prepared by spin coating. The specific method involves uniformly mixing the obtained photocatalyst with PVDF and DMF, wherein the mass ratio of photocatalyst to PVDF is 6:1, and adding an appropriate amount of DMF to form a homogeneous mixture. The photocatalyst coating amount is 5 g / m². 2 Spin-coating onto the FTO glass plate of the constructed flat-plate photovoltaic hydrogen production reactor;

[0069] Figure 4 The XRD patterns of CdS, Pt / CdS, P / CdS and PtP3@PEF / CdS are shown. CdS has a hexagonal non-centrosymmetric structure. The electronegative groups on the surface will generate a polarization electric field. It has high crystallinity. There are no diffraction peaks corresponding to Pt and P elements, indicating that Pt and P elements are low and exist in atomic or ionic states.

[0070] Figure 5The SEM images of CdS and PtP3@PEF / CdS show that CdS is dendritic, mimicking the shape of leaves in nature that can perform photosynthesis, thus making better use of light energy. The morphology of PtP3@PEF / CdS is not significantly different from that of CdS, still maintaining a leaf-like shape, and there is no particulate secondary component on the surface, indicating that Pt-P3 is attached to the surface of CdS in an atomically dispersed state.

[0071] Figure 6 The XPS spectrum of PtP3@PEF / CdS shows the presence of Pt, P, Cd, and S, indicating that the target product was successfully synthesized.

[0072] Figure 7 The charge density difference diagram of the PtP3@PEF / CdS system obtained by theoretical calculation shows that electrons migrate from CdS to Pt-P3 units, indicating that Pt-P3 has electron-withdrawing properties and strong electronegativity, which can promote the migration of photogenerated electrons from CdS to the active sites on the catalyst surface, forming an effective electron transport channel and thus reducing electron-hole recombination.

[0073] Figure 8 The UV-Vis absorption spectra of CdS and PtP3@PEF / CdS show that the light absorption intensity of PtP3@PEF / CdS is significantly higher than that of CdS alone, and the broadened light absorption range allows for the utilization of a wider spectrum of light energy, effectively improving the photon efficiency.

[0074] Figure 9 The steady-state fluorescence spectra of CdS and PtP3@PEF / CdS show that the fluorescence intensity of CdS alone is relatively high, indicating severe electron-hole recombination. In contrast, the fluorescence peak intensity of PtP3@PEF / CdS is significantly reduced, indicating that the electron-hole recombination problem has been effectively solved. This is attributed to the fact that the electronegative Pt-P3 groups on the CdS surface can form an efficient electron migration pathway, creating a transport channel for electrons to migrate to the catalyst surface. Furthermore, the constructed polarized electric field effectively alleviates the electron-hole recombination caused by the Coulomb electric field.

[0075] Figure 10 Transient fluorescence spectra and carrier lifetime analysis of CdS and PtP3@PEF / CdS showed that the lifetime of photogenerated carriers was significantly reduced after the introduction of the single-atom group Pt-P3 onto the CdS surface, indicating that photogenerated electrons can quickly migrate to the active sites on the photocatalyst surface. This is due to the formation of efficient electron transport pathways and the effective electron-withdrawing ability of the Pt-P3 group.

[0076] Figure 11 To assess the photocatalytic hydrogen production activity of water splitting in different control samples, the hydrogen production rate of PtP3@PEF / CdS was significantly improved, reaching 1.22 mol h⁻¹.-1 g -1 (6.1 mol h) -1 m -2 ).

[0077] The photocatalyst and photocatalytic device provided by this invention have the following mechanism analysis and effects:

[0078] (1) This invention solves the problem of instability in single-atom systems: Based on the principle that the triangular structure is the most stable, three P atoms are used to anchor the Pt single atom, forming a stable coordination environment, constructing a stable local microenvironment, and constructing an efficient charge transfer path;

[0079] (2) The present invention solves the problem that high oxidation state coordination atoms will reduce catalytic activity: the electronegativity of P atoms is moderate, which solves the problem of high oxidation state or high coordination number of single-atom metal sites caused by conventionally used high electronegativity coordination atoms such as O, N and S;

[0080] (3) The present invention solves the problem of Coulomb force inside semiconductor: Pt-P3 groups are loaded on the surface of CdS, so that electrons are redistributed in space. The spatial asymmetry of positive and negative electric dipoles forms a polarization electric field (PEF) opposite to the Coulomb electric field inside CdS. PtP3@PEF / CdS is constructed to resist the effect of Coulomb force, reduce the amount of Pt, improve the atomic utilization, fully expose active sites, reduce the hydrogen production overpotential of semiconductor, improve the conductivity of semiconductor system, and shorten the migration distance of photogenerated electrons and holes;

[0081] (4) The present invention solves the problem of photogenerated electron-hole recombination: the electronegative group Pt-P3 is loaded on the surface of CdS. The electron-withdrawing effect of the electronegative group makes the photogenerated electrons migrate rapidly from CdS to Pt-P, effectively suppressing the problem of easy electron-hole recombination caused by the strong Coulomb electric field inside CdS.

[0082] (5) The present invention solves the problem of easy aggregation of metal single atoms loaded on organic carriers: metal single atoms are loaded on metal sulfides by using a simple and easy-to-operate physical adsorption method and calcination method to form strong chemical bond interaction, prevent single atom aggregation and have a stable structure;

[0083] (6) The present invention solves the problems of laboratory batch reaction: a flat-plate square meter photovoltaic hydrogen production device is designed and built, which consists of a reaction module, a liquid drive module, a gas-liquid separation module and a detection and control module. The cooperation of multiple modules meets the requirements of square meter reaction in the pilot stage. ITO glass with good light transmittance is used as the light window and FTO glass with good conductivity is used as the carrier. Liquid and gas flow channels are constructed in the sealed flat-plate glass reaction device. The liquid flow in the reaction system can make the reaction solution fully contact the catalyst. The gaseous products generated during the reaction process can also be carried out from the reaction system with the flowing liquid.

[0084] (7) This invention solves the problem of low photovoltaic hydrogen production rate at present: The CdS system photocatalyst modified by the polarization electric field is coated on a flat-plate, square meter-scale pilot photovoltaic hydrogen production device. PVDF and DMF are used as binders, which not only does not affect the conductivity of the photocatalyst, but also enables the material to adhere well to the glass carrier. For the first time, the photocatalytic water splitting hydrogen production rate on the molar scale has been achieved, realizing the transformation from laboratory research to industrial scale-up experiment.

[0085] Example 1

[0086] This embodiment provides one implementation of a method for preparing a molar-scale hydrogen production photocatalyst PtP3@PEF / CdS with enhanced polarization electric field:

[0087] 1. Dissolve 4.0 mmol CdCl2·2.5H2O in 10 ml of deionized water and label it as solution A; dissolve 4.0 mmol thiourea in 10 ml of deionized water and label it as solution B.

[0088] 2. Add solution B dropwise to solution A while stirring to obtain a homogeneous mixed solution;

[0089] 3. Add 0.5 ml of hydrofluoric acid to the mixed solution obtained in step 2, and stir for 2 hours to ensure thorough mixing;

[0090] 4. Transfer the suspension obtained in step 3 to a polytetrafluoroethylene reactor, heat it from room temperature to 160°C in a drying oven and keep it at that temperature for 15 hours. After the reaction is complete, allow it to cool naturally to room temperature.

[0091] 5. Centrifuge the product obtained in step 4, wash it once with deionized water and ethanol, collect the precipitate, and finally dry the precipitate in a drying oven at 60°C for 6 h, and grind it thoroughly to obtain the CdS catalyst.

[0092] 6. Disperse 0.1 g of the CdS powder obtained in step 5 in 10 ml of the 0.05 mmol / L H2PtCl6 solution prepared in a volumetric flask, stir for 1 h, and then place it in a drying oven at 60 °C for 15 h. Grind the dried solid thoroughly.

[0093] 7. Mix and grind the powder obtained in step 6 with 0.1 g NaH2PO2, then place it in a tube furnace and calcine it under an inert atmosphere (argon, nitrogen). The temperature is increased to 350°C at a rate of 2°C, and the calcination time is 10 min. After cooling to room temperature, grind it to obtain PtP3@PEF / CdS photocatalyst.

[0094] Example 2

[0095] This embodiment provides one implementation of a method for preparing a molar-scale hydrogen production photocatalyst PtP3@PEF / CdS with enhanced polarization electric field:

[0096] 1. Dissolve 4.0 mmol CdCl2·2.5H2O in 20 ml of deionized water and label it as solution A; dissolve 4.0 mmol thiourea in 20 ml of deionized water and label it as solution B.

[0097] 2. Add solution B dropwise to solution A while stirring to obtain a homogeneous mixed solution;

[0098] 3. Add 1 ml of hydrofluoric acid to the mixed solution obtained in step 2, and stir for 3 hours to ensure thorough mixing;

[0099] 4. Transfer the suspension obtained in step 3 to a polytetrafluoroethylene reactor, heat it from room temperature to 160°C in a drying oven and keep it at that temperature for 15 hours. After the reaction is complete, allow it to cool naturally to room temperature.

[0100] 5. Centrifuge the product obtained in step 4, wash it three times with deionized water and ethanol until the supernatant is transparent, collect the precipitate, and finally dry the precipitate in a drying oven at 60°C for 8 hours. Grind it thoroughly to obtain the CdS catalyst.

[0101] 6. Disperse 0.1 g of the CdS powder obtained in step 5 in 20 ml of the 0.15 mmol / L H2PtCl6 solution prepared in a volumetric flask, stir for 2 h, and then place it in a drying oven at 100 °C for 15 h. Grind the dried solid thoroughly.

[0102] 7. Mix and grind the powder obtained in step 6 with 0.2 g NaH2PO2, then place it in a tube furnace and calcine it under an inert atmosphere (argon, nitrogen). The temperature is increased to 400℃ at a rate of 8℃, and the calcination time is 10 min. After cooling to room temperature, grind it to obtain PtP3@PEF / CdS photocatalyst.

[0103] Example 3

[0104] This embodiment provides one implementation of a method for preparing a molar-scale hydrogen production photocatalyst PtP3@PEF / CdS with enhanced polarization electric field:

[0105] 1. Dissolve 5.0 mmol CdCl2·2.5H2O in 20 ml of deionized water and label it as solution A; dissolve 5.0 mmol thiourea in 20 ml of deionized water and label it as solution B.

[0106] 2. Add solution B dropwise to solution A while stirring to obtain a homogeneous mixed solution;

[0107] 3. Add 1.5 ml of hydrofluoric acid to the mixed solution obtained in step 2, and stir for 4 hours to ensure thorough mixing;

[0108] 4. Transfer the suspension obtained in step 3 to a polytetrafluoroethylene reactor, heat it from room temperature to 200°C in a drying oven and keep it at that temperature for 20 h. After the reaction is complete, allow it to cool naturally to room temperature.

[0109] 5. Centrifuge the product obtained in step 4, wash it three times with deionized water and ethanol until the supernatant is transparent, collect the precipitate, and finally dry the precipitate in a drying oven at 110°C for 10 h. Grind it thoroughly to obtain the CdS catalyst.

[0110] 6. Disperse 0.2 g of the CdS powder obtained in step 5 in 30 ml of the 0.05 mmol / L H2PtCl6 solution prepared in a volumetric flask using ultrasonication. Stir for 3 h, then place in a drying oven at 80 °C for 18 h and grind the resulting solid thoroughly.

[0111] 7. Mix and grind the powder obtained in step 6 with 0.2 g NaH2PO2, then place it in a tube furnace and calcine it under an inert atmosphere (argon, nitrogen). The temperature is increased to 300°C at a rate of 5°C, and the calcination time is 30 min. After cooling to room temperature, grind it to obtain the PtP3@PEF / CdS photocatalyst.

[0112] Example 4

[0113] This embodiment provides one implementation of a method for preparing a molar-scale hydrogen production photocatalyst PtP3@PEF / CdS with enhanced polarization electric field:

[0114] 1. Dissolve 6.0 mmol CdCl2·2.5H2O in 30 ml of deionized water and label it as solution A; dissolve 6.0 mmol thiourea in 30 ml of deionized water and label it as solution B.

[0115] 2. Add solution B dropwise to solution A while stirring to obtain a homogeneous mixed solution;

[0116] 3. Add 1.5 ml of hydrofluoric acid to the mixed solution obtained in step 2, and stir for 3 hours to ensure thorough mixing;

[0117] 4. Transfer the suspension obtained in step 3 to a polytetrafluoroethylene reactor, heat it from room temperature to 160°C in a drying oven and keep it at that temperature for 15 hours. After the reaction is complete, allow it to cool naturally to room temperature.

[0118] 5. Centrifuge the product obtained in step 4, wash it three times with deionized water and ethanol until the supernatant is transparent, collect the precipitate, and finally dry the precipitate in a drying oven at 60°C for 6 h, and grind it thoroughly to obtain the CdS catalyst.

[0119] 6. Disperse 0.2 g of the CdS powder obtained in step 5 in 50 ml of the 0.15 mmol / L H2PtCl6 solution prepared in a volumetric flask, stir for 5 h, and then place it in a drying oven at 100 °C for 15 h. Grind the dried solid thoroughly.

[0120] 7. Mix and grind the powder obtained in step 6 with 0.2 g NaH2PO2, then place it in a tube furnace and calcine it under an inert atmosphere (argon, nitrogen). The temperature is increased to 400℃ at a rate of 5℃, and the calcination time is 20 min. After cooling to room temperature, grind it to obtain PtP3@PEF / CdS photocatalyst.

[0121] Example 5

[0122] This embodiment provides one implementation of a method for preparing a molar-scale hydrogen production photocatalyst PtP3@PEF / CdS with enhanced polarization electric field:

[0123] 1. Dissolve 5.0 mmol CdCl2·2.5H2O in 20 ml of deionized water and label it as solution A; dissolve 5.0 mmol thiourea in 20 ml of deionized water and label it as solution B.

[0124] 2. Add solution B dropwise to solution A while stirring to obtain a homogeneous mixed solution;

[0125] 3. Add 1 ml of hydrofluoric acid to the mixed solution obtained in step 2 and stir for 3 hours to ensure thorough mixing;

[0126] 4. Transfer the suspension obtained in step 3 to a polytetrafluoroethylene reactor, heat it from room temperature to 180°C in a drying oven and keep it at that temperature for 20 hours. After the reaction is complete, allow it to cool naturally to room temperature.

[0127] 5. Centrifuge the product obtained in step 4, wash it three times with deionized water and ethanol until the supernatant is transparent, collect the precipitate, and finally dry the precipitate in a drying oven at 80°C for 8 h, and grind it thoroughly to obtain the CdS catalyst.

[0128] 6. Disperse 0.2 g of CdS powder obtained in step 5 in 30 ml of 0.10 mmol / L H2PtCl6 solution prepared in a volumetric flask using ultrasonication. Stir for 3 h, then place in a drying oven at 80 °C for 18 h and grind the resulting solid thoroughly.

[0129] 7. Mix and grind the powder obtained in step 6 with 0.2 g NaH2PO2, then place it in a tube furnace and calcine it under an inert atmosphere (argon, nitrogen). The temperature is increased to 300°C at a rate of 5°C, and the calcination time is 30 min. After cooling to room temperature, grind it to obtain the PtP3@PEF / CdS photocatalyst.

[0130] Example 6

[0131] This embodiment provides one implementation of a method for preparing a molar-scale hydrogen production photocatalyst PtP3@PEF / CdS with enhanced polarization electric field:

[0132] 1. Dissolve 5.0 mmol CdCl2·2.5H2O in 20 ml of deionized water and label it as solution A; dissolve 5.0 mmol thiourea in 20 ml of deionized water and label it as solution B.

[0133] 2. Add solution B dropwise to solution A while stirring to obtain a homogeneous mixed solution;

[0134] 3. Add 0.5 ml of hydrofluoric acid to the mixed solution obtained in step 2, and stir for 4 hours to ensure thorough mixing;

[0135] 4. Transfer the suspension obtained in step 3 to a polytetrafluoroethylene reactor, heat it from room temperature to 200°C in a drying oven and keep it at that temperature for 20 h. After the reaction is complete, allow it to cool naturally to room temperature.

[0136] 5. Centrifuge the product obtained in step 4, wash it three times with deionized water and ethanol until the supernatant is transparent, collect the precipitate, and finally dry the precipitate in a drying oven at 110°C for 10 h. Grind it thoroughly to obtain the CdS catalyst.

[0137] 6. Disperse 0.3 g of the CdS powder obtained in step 5 in 50 ml of the 0.15 mmol / L H2PtCl6 solution prepared in a volumetric flask using ultrasonication. Stir for 3 h, then place in a drying oven at 100 °C for 20 h and grind the resulting solid thoroughly.

[0138] 7. Mix and grind the powder obtained in step 6 with 0.2 g NaH2PO2, then place it in a tube furnace and calcine it under an inert atmosphere (argon, nitrogen). The temperature is increased to 350°C at a rate of 5°C, and the calcination time is 50 min. After cooling to room temperature, grind it to obtain the PtP3@PEF / CdS photocatalyst.

[0139] Example 7

[0140] This embodiment provides one implementation of a method for preparing a molar-scale hydrogen production photocatalyst PtP3@PEF / CdS with enhanced polarization electric field:

[0141] 1. Dissolve 6.0 mmol CdCl2·2.5H2O in 30 ml of deionized water and label it as solution A; dissolve 6.0 mmol thiourea in 30 ml of deionized water and label it as solution B.

[0142] 2. Add solution B dropwise to solution A while stirring to obtain a homogeneous mixed solution;

[0143] 3. Add 1.5 ml of hydrofluoric acid to the mixed solution obtained in step 2, and stir for 4 hours to ensure thorough mixing;

[0144] 4. Transfer the suspension obtained in step 3 to a polytetrafluoroethylene reactor, heat it from room temperature to 200°C in a drying oven and keep it at that temperature for 24 hours. After the reaction is complete, allow it to cool naturally to room temperature.

[0145] 5. Centrifuge the product obtained in step 4, wash it 4 times with deionized water and ethanol until the supernatant is transparent, collect the precipitate, and finally dry the precipitate in a drying oven at 110℃ for 10 h, and grind it thoroughly to obtain the CdS catalyst.

[0146] 6. Disperse 0.3 g of the CdS powder obtained in step 5 in 50 ml of the 0.15 mmol / L H2PtCl6 solution prepared in a volumetric flask, stir for 5 h, and then place in a drying oven at 100 °C for 20 h. Grind the dried solid thoroughly.

[0147] 7. Mix and grind the powder obtained in step 6 with 0.3 g NaH2PO2, then place it in a tube furnace and calcine it under an inert atmosphere (argon, nitrogen). The temperature is increased to 400℃ at a rate of 8℃, and the calcination time is 50 min. After cooling to room temperature, grind it to obtain PtP3@PEF / CdS photocatalyst.

[0148] Test case

[0149] The composite photocatalysts from Examples 1-7 were used to conduct photocatalytic water splitting for hydrogen production experiments. The reaction conditions were as follows: the instrument consisted of a light source, reaction equipment, a magnetically controlled gas circulation device, a vacuum device, a data acquisition device, and a chromatographic testing device. The photocatalytic water splitting hydrogen production system was connected to a gas chromatograph (GC), and the generated gas was injected into the GC for analysis. The GC was equipped with a thermal conductivity detector (TCD), using a 5A molecular sieve as the chromatographic column, and high-purity N2 as the carrier gas. The experimental parameters were set as follows: the TCD device was set to 150°C, the vaporization chamber to 110°C, and the chromatographic column to 50°C.

[0150] The specific procedure for the photocatalytic hydrogen evolution experiment is as follows: The obtained photocatalyst is mixed uniformly with PVDF and DMF, wherein the mass ratio of photocatalyst to PVDF is 6:1, and an appropriate amount of DMF is added to form a homogeneous mixture. The photocatalyst coating amount is 5 g / m². 2 The photocatalyst was spin-coated onto the FTO glass plate of the constructed flat-panel photovoltaic hydrogen production reactor. Lactic acid and deionized water in a volume ratio of 10 vol%:90 vol% were used as the reaction solution. A 300 W xenon lamp was used as the simulated light source, and an optical filter (λ>420 nm, AM=1.5) was used to filter the ultraviolet light. The hydrogen production rate was detected by gas chromatography. Before illumination, high-purity N2 was introduced to degas the entire system (including the solution) to remove O2 from the device. The temperature of the reaction system was maintained at 10±0.5℃ using a constant-temperature water bath. The hydrogen production test results are shown in Table 1, indicating that the hydrogen production rate of the photocatalyst in this system reached 1.22 mol h⁻¹. -1 g -1 (6.1mol h) -1 m -2 This marks the first time that a hydrogen production rate on the molar scale has been achieved, far exceeding existing technologies.

[0151] Table 1. Comparison of hydrogen production rates from photocatalytic water splitting

[0152]

[0153] Comparison Example

[0154] To compare the photocatalytic performance of this system in water splitting for hydrogen production, the hydrogen production rates of the CdS composite photocatalysts are listed below. Patent CN112808280A discloses an S-doped TiO2-CdS photocatalyst, which achieves an optimal hydrogen production rate of approximately 1.31 mmol / h under 300W xenon lamp illumination. -1 g -1 (0.00131 mol h) -1 g -1 Patent CN112121834A discloses an MXene / CdS composite photocatalyst with an optimal hydrogen production rate of approximately 3.71 mmol h⁻¹ g⁻¹ (0.00371 mol h⁻¹). -1 g -1 Patent CN113398998A discloses a Zr-MOF@CdS photocatalyst with an optimal hydrogen production rate averaging approximately 1.86 mmol / h. -1 g -1 (0.00186 mol h) -1 g -1 Patent CN103381367A discloses a CdS / Ba 0.9 Zn 0.1 The optimal hydrogen production rate of the TiO3 composite photocatalyst is approximately 1.47 mmol / h. -1 g -1 (0.00147 mol h) -1 g -1 Patent CN201910706168.7 discloses a Pt single-atom modified catalyst CdS@CDs / Pt-SAs, achieving a hydrogen production efficiency of up to 45.5 mmol / h. -1 g -1 (0.0455 mol h) -1 g -1 These catalysts did not achieve hydrogen production rates at the molar level. Therefore, the molar-scale hydrogen production photocatalyst synthesized in this invention exhibits significantly higher photocatalytic water splitting performance for hydrogen production.

[0155] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A molar-scale hydrogen production photocatalyst with enhanced polarization electric field, characterized in that, The photocatalyst is PtP3@PEF / CdS, which includes a CdS support and a Pt-P3 single-atom group supported thereon. The Pt-P3 single-atom group has an electron-withdrawing function. The photocatalyst PtP3@PEF / CdS is used to achieve a molar-level photocatalytic water splitting hydrogen production rate. In this structure, Pt atoms are anchored by three P atoms to form a stable Pt-P3 coordination structure, thereby generating a polarization electric field PEF on the CdS surface that is opposite to the direction of the internal Coulomb electric field.

2. The polarization-enhanced molar-scale hydrogen production photocatalyst according to claim 1, characterized in that, The Pt atoms are atomically dispersed with 100% atomic utilization, and each Pt atom serves as a hydrogen-producing active site.

3. A method for preparing a molar-scale hydrogen production photocatalyst with enhanced polarization electric field, characterized in that, The preparation method described above is used to prepare a molar-scale hydrogen production photocatalyst with enhanced polarization electric field as described in any one of claims 1-2, and includes the following steps: S1. Dissolve the cadmium source and the sulfur source in deionized water to form solution A and solution B respectively. Mix solution A and solution B, add strong acid, and stir to form a suspension. S2. The suspension is heated and kept at a constant temperature for reaction, then cooled, centrifuged, washed and dried to obtain CdS catalyst powder; S3. The CdS catalyst powder is ultrasonically dispersed in a platinum salt solution, stirred, and then dried. S4. The dried product obtained in step S3 is mixed and ground with a phosphorus source, calcined under an inert atmosphere, and then cooled and ground to obtain PtP3@PEF / CdS photocatalyst.

4. The method for preparing a molar-scale hydrogen production photocatalyst with enhanced polarization electric field according to claim 3, characterized in that, In step S1, the cadmium source is selected from at least one of cadmium chloride, cadmium nitrate, cadmium sulfate, or cadmium acetate; The sulfur source is selected from at least one of thiourea, sodium sulfide, sodium thiosulfate, or urea. The strong acid is selected from at least one of hydrofluoric acid, hydrobromic acid, hydrochloric acid, nitric acid, or sulfuric acid.

5. The method for preparing a molar-scale hydrogen production photocatalyst with enhanced polarization electric field according to claim 3, characterized in that, In step S1, the amount of cadmium source used is 4.0-6.0 mmol, the amount of sulfur source used is 4.0-6.0 mmol, the amount of deionized water used is 10-30 ml, the amount of strong acid used is 0.5-1.5 ml, and the stirring time is 2-4 h.

6. The method for preparing a molar-scale hydrogen production photocatalyst with enhanced polarization electric field according to claim 3, characterized in that, In step S2, the suspension is heated to 160-200°C and the reaction time is 15-24 h.

7. The method for preparing a molar-scale hydrogen production photocatalyst with enhanced polarization electric field according to claim 3, characterized in that, In step S3, the platinum salt is selected from at least one of chloroplatinic acid, platinum nitrate, platinum sulfate, or platinum chloride; The solution concentration is 0.05-0.15 mmol / L, and the drying temperature is 60-100℃.

8. The method for preparing a molar-scale hydrogen production photocatalyst with enhanced polarization electric field according to claim 3, characterized in that, In step S4, the calcination temperature is 200-400℃, the calcination time is 10-50 min, and the heating rate is 2-8℃ / min. The phosphorus source is selected from at least one of sodium hypophosphite, disodium hydrogen phosphate, potassium dihydrogen phosphate, or sodium monohydrogen phosphate.

9. The application of a molar-scale hydrogen production photocatalyst with enhanced polarization electric field in the catalytic splitting of water to produce hydrogen, characterized in that, The photocatalyst is prepared by the preparation method according to any one of claims 3-8.

10. The application of the polarization electric field-enhanced molar-scale hydrogen production photocatalyst according to claim 9 in the catalytic water splitting for hydrogen production, characterized in that, The application is to use the photocatalyst to catalytically decompose water to produce hydrogen in a flat-panel, square-scale photovoltaic hydrogen production device. The device includes a reaction module, a liquid driving module, a gas-liquid separation module, and a detection and control module. The photocatalyst is coated onto the conductive glass carrier of the device with an adhesive. The reaction module has a light-transmitting window and a catalyst support. The light-transmitting window is made of ITO glass, and the catalyst support is made of FTO glass. Liquid and gas flow channels are constructed inside. The liquid drive module is used to circulate the reaction solution, ensuring that the solution is in full contact with the catalyst. The gas-liquid separation module is used to separate the generated hydrogen gas; The detection and control module is used for online detection and measurement of gas production.

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