Multi-defect ultrathin pt nanosheets and methods of making the same

Abstract

This invention provides a multi-defect ultrathin Pt nanosheet and its preparation method, comprising the following steps: preparing an LDHs precursor material and calcining the LDHs precursor material to obtain an LDO with a structure memory effect; dispersing the LDO in a solution containing a Pt-based precursor, reconstructing it into a layered LDHs template using the structure memory effect, and allowing the Pt-based precursor to enter the interlayer space of the layered LDHs template to obtain a Pt precursor intercalation complex; heat-treating the Pt precursor intercalation complex under a reducing atmosphere to reduce the interlayer Pt precursor in situ, and allowing it to grow in a confined space within the two-dimensional interlayer space of the layered LDHs template to form Pt nanosheets, obtaining a Pt-LDO complex; and using an acidic solution to etch and remove the layered template from the Pt-LDO complex to obtain multi-defect ultrathin Pt nanosheets, thereby solving the problems of low atom utilization of existing Pt nanoparticle catalysts, easy migration and poor stability of ultra-small Pt species, and limited preparation routes for two-dimensional Pt nanosheets.

Description

Technical Field

[0001] This invention relates to the field of nanomaterial preparation technology, specifically to a multi-defect ultrathin Pt nanosheet and its preparation method, as well as the multi-defect ultrathin Pt nanosheet prepared by this method and its application in the field of electrocatalysis. Background Technology

[0002] Noble metal catalysts exhibit high activity in various catalytic processes, including electrocatalysis and thermocatalysis, due to their superior surface electronic structure and ability to regulate reaction intermediates. Pt, Ir, and Ru are particularly representative examples. Taking the electrocatalytic hydrogen evolution reaction (HER) as an example, Pt is still widely considered an important benchmark material for evaluating HER catalytic performance, and its intrinsic activity and reaction kinetic advantages remain difficult to completely replace with other materials.

[0003] However, Pt in current catalytic engineering applications is mostly in the form of nanoparticles. For conventional Pt nanoparticles, a large number of Pt atoms are located inside the particle and cannot directly participate in surface catalytic reactions, resulting in low utilization of the noble metal atoms and difficulty in fully utilizing Pt's high intrinsic activity. To improve Pt utilization efficiency, researchers often try to increase the proportion of exposed atoms by reducing particle size, constructing ultrasmall clusters, or even single-atom sites. Although these strategies improve the surface utilization of Pt to some extent, under high loading, long-term operation, or heat treatment conditions, ultrasmall Pt species are still prone to migration, aggregation, or structural evolution, leading to the masking of active sites, degradation of catalytic performance, and a decrease in noble metal utilization.

[0004] In contrast, two-dimensional ultrathin noble metal nanomaterials, possessing high surface atom exposure, a continuous conductive framework, and a relatively short mass transfer path, are considered important structural morphologies for improving noble metal utilization and enhancing interfacial reaction efficiency. In recent years, two-dimensional Pt group metal nanocrystals have shown promising applications in electrocatalysis due to their high specific surface area, abundant low-coordination surface sites, and tunable electronic structure. Ultrathin Pt nanosheets, in particular, hold the promise of maintaining the conductive characteristics of the continuous metal phase while achieving a higher proportion of exposed surface Pt atoms, thus balancing high activity and high stability.

[0005] However, the controllable preparation of ultrathin Pt nanosheets still faces significant challenges. On the one hand, Pt has high surface energy, making it prone to three-dimensional growth and aggregation during reduction crystallization. On the other hand, existing Pt nanosheet preparation routes typically rely on molten salt methods or topological reduction methods using special layered platinum acid precursors. While these methods can yield two-dimensional Pt structures, they often suffer from problems such as strong precursor specificity, limited process conditions, or insufficient versatility. For example, a published patent has reported a method for preparing Pt nanosheets with a thickness of approximately 20 nm in a molten salt system (CN101791702B); another document reports obtaining bilayer Pt nanosheets of 0.6 nm and below through topological reduction of layered platinum acid nanosheets (EP4455095A1). These studies demonstrate that two-dimensional Pt nanosheets are feasible, but also indicate that their preparation often depends on specific precursors or specific reaction systems.

[0006] Layered bimetallic hydroxides (LDHs) are a class of layered inorganic materials with tunable lamination composition, exchangeable interlayer anions, and a significant structural memory effect. Studies have shown that LDHs, after calcination to form layered bimetallic oxides (LDOs), can undergo reconstruction in anionic aqueous solutions, restoring their layered structure and re-intercalating target anions. Based on these interlayer confinement and reconstruction intercalation characteristics, LDHs possess unique advantages in the construction of layered composite materials, ion intercalation, and the design of catalytic materials. In existing publications, LDHs have been used to load or composite noble metal nanoparticles, such as Pt nanoparticles modifying the surface of LDHs or Pt nanoparticles entering the interlayer regions of LDHs. However, these are primarily nanoparticle or nanocluster composites, rather than directly confined growth of ultrathin Pt nanosheets within the interlayer of LDHs.

[0007] Therefore, it is necessary to develop a new method for preparing ultrathin Pt nanosheets with a clear structure and controllable process, which can utilize the interlayer confinement effect of LDHs, in order to improve the atomic exposure of Pt surface and the utilization efficiency of noble metals, and provide a new technical path for the construction of efficient noble metal catalytic materials. Summary of the Invention

[0008] The purpose of this invention is to provide multi-defect ultrathin Pt nanosheets and their preparation methods, particularly a multi-defect ultrathin Pt nanosheet based on the interlayer confinement effect and structural memory effect of LDHs and its preparation method, in order to solve the problems of low atom utilization of existing Pt nanoparticle catalysts, easy migration and poor stability of ultra-small Pt species, and limited preparation routes of two-dimensional Pt nanosheets.

[0009] This invention achieves ordered intercalation and restricted reduction growth of Pt precursors by constructing a confined two-dimensional reaction space between layers, thereby obtaining ultrathin Pt nanosheets with high specific surface area, high surface atom exposure, and abundant defect structures.

[0010] To achieve the above objectives, the present invention adopts the following technical solution, comprising the following steps: S1: Preparation of LDO with structural memory effect: LDH precursor materials were prepared and calcined to obtain LDOs with structural memory effect. S2: Preparation of Pt precursor intercalation complex: LDO was dispersed in a solution containing a Pt-based precursor, allowing the LDO to be reconstructed into a layered LDH template using the structural memory effect, and the Pt-based precursor was inserted into the interlayer of the layered LDH template to obtain a Pt precursor intercalation complex. S3: Confined reduction growth: The Pt precursor intercalation complex was heat-treated under a reducing atmosphere to reduce the interlayer Pt precursor in situ and form Pt nanosheets in a confined growth in the two-dimensional interlayer space, thus obtaining the Pt-LDO complex. S4: Template etching yields multi-defect ultrathin Pt nanosheets: The layered template in the Pt-LDO composite was removed by etching with an acidic solution to obtain multi-defect ultrathin Pt nanosheets.

[0011] In step S1: Preferably, the calcination treatment is carried out at a temperature of 300~800 ℃ for 2~8 h.

[0012] When the LDH precursor material is calcined at 300 ℃ to 800 ℃, the interlayer anions will decompose and be removed, forming amorphous or spinel-type composite metal oxides. When the calcined composite metal oxides are redispersed in an aqueous solution containing the target anions, the LDO will spontaneously "memorize" the original LDH layered structure, reassemble it to form a regular layered structure, and at the same time incorporate the target anions in the solution into the interlayer, completing the intercalation process.

[0013] Preferably, the precursor material for LDHs is a binary or multi-component layered metal hydroxide such as magnesium-aluminum, zinc-aluminum, calcium-aluminum, or nickel-aluminum.

[0014] In step S2: Utilizing the structural memory effect of LDO, it is placed in a solution containing Pt-based precursor ions to reconstruct a layered LDH template, thereby achieving interlayer intercalation and uniform distribution of Pt precursor ions, enabling the Pt precursor ions to achieve molecular-level confined distribution in the two-dimensional interlayer space.

[0015] Preferably, the Pt precursor is an intercalable anionic Pt complex.

[0016] Preferably, the reduction process is carried out in a reducing atmosphere to promote the transformation of Pt species into the metallic state while maintaining the two-dimensional confined structure.

[0017] This method involves structural memory reconstruction of the LDO in a solution containing platinum complex anions, restoring the formation of a layered LDH template. During this reconstruction process, the platinum complex anions are introduced into the two-dimensional space between the layers of the layered LDH template, rather than being scattered and adsorbed on the outer surface of the layered LDO template. At the same time, electrostatic adsorption allows Pt ions to achieve uniform molecular-level dispersion between the layers, avoiding local enrichment of Pt-based precursor ions. This provides uniform and controllable reaction sites and confined spaces for the subsequent two-dimensional planar growth of Pt atoms, rather than three-dimensional agglomeration into particles.

[0018] Preferably, the layered LDHs template is a template material with a layered structure, wherein the layers of the layered structure have an inherent net charge, and the interlayers of the layered structure have guest ions that can be replaced.

[0019] Preferably, the layered LDHs template is a template material with a long-range ordered layered structure, possessing continuous and uniform two-dimensional interlayer nanochannels, rather than a disordered pore structure.

[0020] Preferably, the molar ratio of divalent metal cations to trivalent metal cations in the layered LDHs template is 2:1 to 4:1, and this ratio is used to determine the charge density of the layer.

[0021] Preferably, the structure memory effect of LDHs is used to introduce the Pt-based precursor into the interlayer of the layered LDH template. The replaceable guest ions in the interlayer are selected from nitrate, chloride, sulfate, carbonate or hydroxide, etc., to facilitate the intercalation and replacement of the anionic Pt precursor.

[0022] Specifically, LDO is dispersed in a solution containing Pt-based precursor ions and stirred at room temperature or a certain temperature. The platinum complex anions enter the interlayer under the drive of concentration gradient and electrostatic interaction.

[0023] Preferably, the exchange temperature for dispersing LDO in a solution containing Pt-based precursor ions is 60–80 °C, and the exchange time is 12–48 h.

[0024] Preferably, the layered LDHs template has a regular hexagonal morphology, with a lateral dimension between 5 nm and 5000 nm and a thickness that is easily controlled between 20 and 100 nm.

[0025] Furthermore, the XRD pattern of the layered LDHs template has sharp (003) and (006) characteristic diffraction peaks, which proves that the layered structure is highly ordered and the interlayer spacing is uniform, ensuring the uniformity of the intercalation process and avoiding the problems of local non-intercalation and precursor aggregation.

[0026] Preferably, the Pt-based precursor is a platinum source capable of forming platinum complex anions in solution, and the platinum source is selected from one or more of chloroplatinic acid, sodium platinum, potassium chloroplatinate, and fluoroplatinic acid.

[0027] Preferably, the Pt-based precursor is selected from one or more of hexachloroplatinate, hexafluoroplatinate, and platinum.

[0028] In step S3: After introducing Pt-based precursor ions into the interlayer of layered LDH templates to obtain Pt precursor intercalation complexes, the Pt precursor intercalation is then heat-treated under a reducing atmosphere to obtain Pt-LDO complexes composed of ultrathin Pt nanosheets.

[0029] The reducing atmosphere in this scheme is a mixture of hydrogen and inert gas, with hydrogen accounting for 5% to 20% of the volume.

[0030] Preferably, the volume of hydrogen is 5%.

[0031] In some embodiments, the heat treatment temperature is 300 °C to 800 °C, and the heat treatment time is 1 to 5 h. It should be particularly noted that, due to the heterogeneous charge coupling environment formed between the Pt-based precursor ions and the layered template, the higher temperature heat treatment, under the influence of interlayer confinement and template constraint, helps Pt species reduction and lattice rearrangement, and can suppress the disordered aggregation of Pt species to a certain extent.

[0032] Preferably, the heat treatment temperature is 400 ℃~600 ℃ and the heat treatment time is 2 h.

[0033] Preferably, during the heat treatment process, the reconstructed layered LDHs template is transformed into a corresponding composite metal oxide framework, which can still provide lamellar confinement and spatial constraint to a certain extent, thereby inhibiting the aggregation of Pt species towards three-dimensional particles.

[0034] In step S4: In some embodiments, an acidic solution is selected and etching is performed under mild acidic conditions.

[0035] Specifically, the acidic solution is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid, and acetic acid.

[0036] In some embodiments, the ratio of acidic solution to Pt-LDO complex is greater than 1:1 to ensure that the layered template can be fully etched away.

[0037] In some embodiments, the thickness of the multi-defect ultrathin Pt nanosheets is only 1~3 nm. In addition, the multi-defect ultrathin Pt nanosheets prepared by this method can be applied to the field of electrocatalysis.

[0038] Compared with existing technologies, this technical solution has the following characteristics and beneficial effects: (1) By utilizing the interlayer confinement effect of LDHs, the three-dimensional aggregation of Pt during the reduction process is effectively suppressed, thereby achieving the directional growth of two-dimensional structures. This invention uses interlayer LDHs templates as a two-dimensional confined reaction field, which can effectively suppress the disordered three-dimensional growth and aggregation of Pt during the reduction process, thus facilitating the formation of ultrathin two-dimensional Pt structures. This effect differs from the conventional Pt nanoparticle route and also from the composite method of simply loading Pt nanoparticles onto the surface or between layers of LDHs.

[0039] (2) The Pt nanosheets obtained by this invention have a small thickness, adjustable lateral dimensions, and a high proportion of exposed Pt atoms on the surface, which is beneficial to improving the utilization efficiency of noble metals. The two-dimensional Pt structure itself is widely regarded as having high surface atom utilization and excellent interfacial mass transfer characteristics. Therefore, the material of this invention has a structural advantage in catalytic applications. Specifically, the multi-defect ultrathin Pt nanosheets prepared by this method have a thickness of 1–3 nm, and the surface atom ratio is significantly increased, thereby improving the utilization efficiency of noble metals; (3) The structural memory effect of LDHs is utilized to achieve uniform intercalation and distribution of Pt precursors, enhancing the controllability of the material structure. Specifically, the method of this invention is based on the structural memory effect of LDHs, with a clear preparation route. The thickness, lateral size, and dispersion state of the obtained Pt nanosheets can be adjusted by controlling the composition of LDHs, the interlayer environment, the concentration of Pt precursors, and the reduction conditions, exhibiting good designability. The structural memory effect of LDHs has been systematically studied, therefore this technical solution has a clear materials science basis.

[0040] (4) The prepared material has abundant defect structures (such as lattice distortion, low coordination sites, etc.), which is beneficial to regulate the electronic structure and improve catalytic activity.

[0041] (5) The ultrathin Pt nanosheets obtained in this invention can be used for catalytic reactions such as electrocatalytic hydrogen evolution. Pt is recognized as a high intrinsic activity as a reference catalyst for HER, and the two-dimensional ultrathin Pt structure has the potential to improve Pt exposure and mass activity; therefore, the material of this invention exhibits high Pt utilization efficiency in the hydrogen evolution reaction. It exhibits a high mass activity, demonstrating excellent performance in the hydrogen evolution reaction, reaching 3698 mA·mV at an overpotential of 55 mV. Significantly superior to commercial Pt / C (282 mA·m·K) )catalyst. Attached Figure Description

[0042] Figure 1 The XRD pattern of the ultrathin Pt nanosheets of Example 1 of this application is shown.

[0043] Figure 2 SEM and TEM images of the ultrathin Pt nanosheets of Example 1 of this application are shown.

[0044] Figure 3 The image shown is an HRTEM image of the ultrathin Pt nanosheets of Example 1 of this application.

[0045] Figure 4 An AFM image of the ultrathin Pt nanosheets of Example 1 of this application is shown.

[0046] Figure 5 The EPR spectrum of the ultrathin Pt nanosheets of Example 1 of this application is shown.

[0047] Figure 6 The following are the evaluation results of the electrocatalytic hydrogen evolution performance of ultrathin Pt nanosheets in Example 1 of this application, wherein... Figure 6 a shows the linear sweep voltammetry curve of commercial 20wt%Pt / C in Example 1 of this application; Figure 6 b shows the mass activity graph of Example 1 of this application, a commercial 20wt% Pt / C.

[0048] Figure 7 The stability test results of Embodiment 1 of this application are shown. Detailed Implementation

[0049] 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 only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0050] Example 1 (1) Al(NO3)3·9H2O, Mg(NO3)2·6H2O and urea were dissolved in deionized water at a molar ratio of 1:3:30 to obtain a mixed solution. The mixed solution was heated to 95 °C and stirred for 24 h. After filtration and washing, it was dried at 60 °C to obtain LDHs solid. (2) LDO was obtained by calcining solid LDHs in a tube furnace at 450 °C for 2 h. 500 mL of aqueous solution of H2PtCl6 with a concentration of 20 mg / mL was prepared. 5 g of LDO powder was dispersed in the aqueous solution containing H2PtCl6 to obtain a mixed slurry. The mixed slurry was stirred at 60 °C for 48 h under nitrogen protection, filtered and washed, and dried at 60 °C to obtain PtCl6. 2- -LDHs.

[0051] (3) PtCl6 2- The Pt-LDHs composite was placed in a tube furnace and calcined at 500 °C for 2 h under a mixed H2 / Ar atmosphere to obtain the Pt-LDO composite.

[0052] (4) The Pt-LDO complex was dispersed in a 0.5 mol / L hydrochloric acid solution, sonicated and stirred for 24 h, filtered, washed and dried to obtain ultrathin Pt nanosheets.

[0053] The ultrathin Pt nanosheets obtained in the above steps were tested, and among them, Figure 1 The XRD (X-ray diffraction) pattern of the ultrathin Pt nanosheet is shown. The XRD pattern shows diffraction peaks at 2θ = 39.8°, 46.3°, 67.5° and 81.3°, which correspond to the (111), (200), (220) and (311) crystal planes of Pt, respectively (JCPDS NO:04-0802), confirming the successful preparation of face-centered cubic Pt nanosheets.

[0054] Figure 2 The SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy) images of the ultrathin Pt nanosheets of Example 1 are shown. The SEM images... Figure 2 a) shows that the Pt nanosheets exhibit an irregular sheet-like morphology; TEM image ( Figure 2 b) Further confirmation of the ultrathin properties of the nanosheets.

[0055] Figure 3 The image shows an HRTEM (High Resolution Transmission Electron Microscopy) image of the ultrathin Pt nanosheets of Example 1. These nanosheets have a crystal plane spacing of 0.23 nm, corresponding to the Pt (111) crystal plane. Simultaneously, significant structural defects are observed within the nanosheets, including localized bending, dislocations, and discontinuities in the lattice fringes, indicating the presence of dislocations and lattice distortion. These abundant defect structures (such as dislocations, grain boundaries, and edge defects) significantly increase the surface unsaturated sites of the material, thereby providing a large number of potential catalytically active sites, which is beneficial for improving its catalytic performance in the hydrogen evolution reaction (HER).

[0056] Figure 4The image shows an AFM (atomic force microscope) image of the ultrathin Pt nanosheets. The synthesized Pt nanosheets are approximately 2 nm thick and have a uniform lateral size distribution between 100 nm and 300 nm.

[0057] Figure 5 The EPR spectrum of the ultrathin Pt nanosheet is shown. The Pt nanosheet's EPR spectrum exhibits a distinct broad peak signal, indicating the presence of paramagnetic centers associated with unpaired electrons in the sample. This signal can generally be attributed to the abundant low-coordinate Pt sites on the Pt nanosheet surface, surface defects, and defect-related spin centers generated by local electronic structure inhomogeneities.

[0058] Example 2 The only difference from the preparation method of Example 1 is that in step (1), equimolar amounts of Zn(NO3)2·6H2O were used to replace Mg(NO3)2·6H2O in Example 1. The rest is the same as in Example 1. The ultrathin Pt nanomaterial of Example 2 was obtained.

[0059] Example 3 The preparation method differs from that of Example 1 only in step (1), where AlCl3 and CaCl2 are used in equimolar ratios to replace Al(NO3)3·9H2O and Mg(NO3)2·6H2O in Example 1, respectively. The rest is the same as in Example 1. The ultrathin Pt nanomaterial of Example 3 is obtained.

[0060] Example 4 The only difference from the preparation method in Example 1 is that in step (2), the LDHs solid is calcined in a tube furnace at 300 °C for 2 h to obtain LDO; the rest is the same as in Example 1. The ultrathin Pt nanomaterials of Example 4 are obtained.

[0061] Example 5 The only difference from the preparation method in Example 1 is that in step (2), the LDHs solid is calcined in a tube furnace at 500 °C for 2 h to obtain LDO; the rest is the same as in Example 1. The ultrathin Pt nanomaterial of Example 5 is obtained.

[0062] Example 6 The only difference from the preparation method in Example 1 is that in step (2), the LDHs solid is calcined in a tube furnace at 800 °C for 2 h to obtain LDO; the rest is the same as in Example 1. The ultrathin Pt nanomaterials of Example 6 are obtained.

[0063] Example 7 The preparation method differs from that in Example 1 only in step (2) where 500 mL of an aqueous solution of H2PtCl6 with a concentration of 10 mg / mL is prepared; the rest is the same as in Example 1. The ultrathin Pt nanomaterials of Example 7 are obtained.

[0064] Example 8 The only difference from the preparation method in Example 1 is that in step (2), the mixed slurry is stirred at 80 °C for 48 h under nitrogen protection; the rest is the same as in Example 1. The ultrathin Pt nanomaterials of Example 8 are obtained.

[0065] Example 9 The only difference from the preparation method in Example 1 is that in step (3), the Pt-LDO composite was obtained by calcination at 300 °C for 2 h under a mixed H2 / Ar atmosphere. The rest is the same as in Example 1. The ultrathin Pt nanomaterial of Example 9 was obtained.

[0066] Example 10 The only difference from the preparation method in Example 1 is that in step (3), the Pt-LDO composite was obtained by calcination at 800 °C for 2 h in a mixed H2 / Ar atmosphere. The rest is the same as in Example 1. The ultrathin Pt nanomaterial of Example 10 was obtained.

[0067] Example 11 The preparation method differs from that of Example 1 only in that the nanoparticles are dispersed in a 1 mol / L hydrochloric acid solution in step (4). The rest is the same as in Example 1. The ultrathin Pt nanomaterials of Example 11 are obtained.

[0068] Performance testing The electrocatalytic hydrogen evolution performance of the ultrathin Pt nanosheets obtained in Example 1 and commercial 20wt% Pt / C was evaluated. The specific evaluation method is as follows: The electrocatalytic samples were tested using a three-electrode system, with a Pt sheet as the counter electrode and an Ag / AgCl (saturated) electrode as the reference electrode. The tests were conducted in H2SO4 (0.5 M) electrode solution at a scan rate of 5 mV / s using a Shanghai Chenhua CHI660e electrochemical workstation. Nitrogen gas was purged before testing to remove dissolved oxygen. The working electrode was prepared as follows: 1 mg of a self-made 20% Pt nanosheet / C catalyst was dispersed in 30 μL of Nafion solution (5 wt%) in 1 mL of a water-ethanol mixture (water:ethanol volume ratio 1:1). After sonication for 1 h, a uniform dispersion was obtained. Subsequently, 5 μL of the dispersion was drop-coated onto the surface of a 4 mm diameter glassy carbon electrode and allowed to air dry. The catalyst polarization curve was tested using linear sweep voltammetry (LSV) at a scan rate of 5 mV / s, and the chronoamperometry (it) curve was tested.

[0069] The LSV curve of the platinum-based catalyst obtained in Example 1 is shown in the figure. Figure 6 As shown in a, the mass activity graph is as follows: Figure 6 As shown in b in the diagram. (By...) Figure 6As can be seen from 'a', when saturated N2 is introduced for hydrogen evolution testing, the platinum catalyst obtained in Example 1 exhibits higher electrocatalytic HER activity, which is superior to the commercial 20% Pt / C catalyst. For a more reasonable comparison of electrocatalytic performance, the HER activities of both Pt nanosheets and 20% Pt / C are normalized to mass activity (see [reference]). Figure 6 (b), that is, given η Current density per unit mass Pt (mA·m) It can be seen that the mass activity of Pt nanosheets is much higher than that of commercial 20% Pt / C.

[0070] Figure 7 The 1-time curve demonstrates its superior stability at 100 mA cm⁻¹. -2 It can be stably maintained for 50 h under high current density. The above-mentioned extraordinary stability does not come solely from the two-dimensional morphology itself, but from the synergistic effect of the specific crystal orientation and interface defect structure formed during the LDHs confined reduction process. This structure can effectively alleviate the Pt dissolution and reconstruction behavior under high current density hydrogen evolution conditions.

[0071] Therefore, the performance improvement obtained by the present invention has a clear structure-performance causal relationship, rather than a simple size effect.

[0072] Those skilled in the art should understand that the technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0073] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for preparing multi-defect ultrathin Pt nanosheets, characterized in that, Includes the following steps: S1: Preparation of LDO with structural memory effect: LDH precursor materials were prepared and calcined to obtain LDOs with structural memory effect. S2: Preparation of Pt precursor intercalation complex: LDO was dispersed in a solution containing a Pt-based precursor, and the structure memory effect was used to reconstruct it into a layered LDH template. The Pt-based precursor was then inserted into the interlayer of the layered LDH template to obtain a Pt precursor intercalation complex. S3: Confined reduction growth: The Pt precursor intercalation complex was heat-treated under a reducing atmosphere to reduce the interlayer Pt precursor in situ and form Pt nanosheets in the two-dimensional interlayer space of the layered LDH template, thus obtaining the Pt-LDO complex. S4: Template etching yields multi-defect ultrathin Pt nanosheets: Acidic solution etching was used to remove the layered template in the Pt-LDO composite, resulting in multi-defect ultrathin Pt nanosheets.

2. The method for preparing multi-defect ultrathin Pt nanosheets according to claim 1, characterized in that, The roasting temperature is 300–800 ℃, and the time is 2–8 h.

3. The method for preparing multi-defect ultrathin Pt nanosheets according to claim 1, characterized in that, The molar ratio of divalent metal cations to trivalent metal cations in the interlayer structure of the layered LDH template is 2:1 to 4:

1.

4. The method for preparing multi-defect ultrathin Pt nanosheets according to claim 1, characterized in that, Layered LDH templates are template materials with a layered structure, wherein the layers of the layered structure have an inherent net charge, and the interlayers of the layered structure have replaceable guest ions, which are selected from one of carbonate, chloride, nitrate, sulfate and hydroxide ions.

5. The method for preparing multi-defect ultrathin Pt nanosheets according to claim 1, characterized in that, The exchange temperature for dispersing LDO in a solution containing Pt-based precursor ions is 60–80 °C, and the exchange time is 12–48 h.

6. The method for preparing multi-defect ultrathin Pt nanosheets according to claim 1, characterized in that, The Pt-based precursor is a platinum source capable of forming platinum complex anions in solution, and the platinum source is selected from one or more of chloroplatinic acid, sodium platinum, potassium chloroplatinate, and fluoroplatinic acid.

7. The method for preparing multi-defect ultrathin Pt nanosheets according to claim 1, characterized in that, The reducing atmosphere is a mixture of hydrogen and inert gas, with hydrogen accounting for 5% to 20% by volume.

8. The method for preparing multi-defect ultrathin Pt nanosheets according to claim 1, characterized in that, The heat treatment temperature is 300–800 °C, and the heat treatment time is 1–5 h.

9. The method for preparing multi-defect ultrathin Pt nanosheets according to claim 1, characterized in that, The acidic solution is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid and acetic acid; the ratio of the acidic solution to the Pt-LDO complex is greater than 1:

1.

10. A multi-defect ultrathin Pt nanosheet, characterized in that, The multi-defect ultrathin Pt nanosheets, with a thickness of 1–3 nm, are prepared according to any one of claims 1 to 9.

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