Battery for generating hydrogen

Abstract

Disclosed herein is a battery for generating hydrogen. The battery comprises a working electrode; a reference electrode; a counter electrode; the electrolyte is sulfuric acid with the concentration of about 0.5 M; wherein the working electrode is prepared by coating a layer of ink on a glassy carbon electrode and air-drying the glassy carbon electrode; and the ink is prepared by mixing the TMD composite material decorated by platinum nanoparticles with a solution to form a mixture and carrying out ultrasonic treatment on the mixture, and the solution is composed of water, ethanol and 5% sulfonated tetrafluoroethylidene fluorinated polymer-copolymer dispersion according to a volume ratio of 4: 1: 0.1.

Description

TECHNICAL FIELD

[0001] The present disclosure generally relates to electrodes having transition metal dichalcogenide (TMD) nanocomposites decorated with platinum (Pt) nanoparticles deposited thereon, and the use of the electrodes to produce hydrogen gas in a battery in a hydrogen evolution reaction (HER). BACKGROUND

[0002] Due to the energy crisis, both academia and industry are interested in developing efficient and low-cost electrocatalysts to produce clean hydrogen energy from the most abundant resource on earth, water, i.e. splitting water to produce hydrogen, also known as the hydrogen evolution reaction (HER). Two-dimensional materials, particularly 2D-TMDs, have become an alternative catalyst option for the HER reaction due to their high volume-to-area ratio and ultrathin structure. Various methods have been proposed to improve the catalytic activity of TMDs, including the incorporation of heteroatoms, the formation of composites, or the introduction of defects or stresses in the lattice, etc. Combining two or more materials to create composites is currently recognized as the most effective way to improve the catalytic activity of TMDs, not only solving the limitations of individual components but also maximizing material strength. Most importantly, in addition to improving performance through the formation of composites, material combinations can also bring new properties. However, the current methods for manufacturing TMD composites are too harsh in reaction conditions, not environmentally friendly, or require high-temperature operation, etc.

[0003] Based on the above, there is an urgent need in the related art to develop a method for manufacturing TMD composites that is not only easier to operate and environmentally friendly, but also has good electrocatalytic activity, and can be used as an electrode to catalyze the HER in a battery to convert hydrogen ions into hydrogen gas. SUMMARY

[0004] In view of the foregoing needs, the present disclosure proposes a method for manufacturing a transition metal dichalcogenide (TMD) nanocomposite that can be used as an electrode and catalyze the hydrogen evolution reaction (HER) in a battery to convert hydrogen ions into hydrogen gas.

[0005] The primary object of the present disclosure is to propose a method for manufacturing a TMD composite decorated with platinum nanoparticles. The method comprises depositing platinum nanoparticles on a TMD monolayer in the presence of a reducing agent, thereby manufacturing the TMD composite decorated with platinum nanoparticles.

[0006] According to embodiments of the present application, each platinum nanoparticle deposited on the TMD monolayer has a size of about 1.2 nm to about 1.6 nm.

[0007] Examples of TMD monolayers suitable for use in the method of the present application include, but are not limited to, a tantalum disulfide monolayer, a titanium disulfide monolayer, and the like. In certain embodiments, the TMD monolayer is a tantalum disulfide monolayer. In other embodiments, the TMD monolayer is a titanium disulfide monolayer.

[0008] According to embodiments of the present application, the TMD monolayer is produced by the following steps:

[0009] (i) discharging a TMD bulk material in a lithium battery to produce a lithiated TMD;

[0010] and

[0011] (ii) sonicating the lithiated TMD in water to exfoliate the lithiated TMD into the TMD monolayer.

[0012] According to embodiments of the present application, in step (i), the lithium battery comprises: an anode made of a lithium foil; a cathode made of a copper foil coated with the TMD bulk material on a surface thereof; and an electrolyte composed of LiPF6, ethylene carbonate (EC), and dimethyl carbonate (DMC).

[0013] According to embodiments of the present application, in step (i), the lithium battery is discharged at a constant current of 0.025 mA and a cutoff voltage of 0.9 V.

[0014] According to embodiments of the present application, the platinum nanoparticles are deposited on the TMD monolayer by the following steps:

[0015] (a) adding the TMD monolayer to a solution composed of the reducing agent, potassium chloroplatinate (K2PtCl4), and water to form a mixture, wherein the molar ratio of the reducing agent to the potassium chloroplatinate in the solution is about 3:2; and

[0016] (b) exposing the mixture to light for about 0.1-2 hours to allow platinum nanoparticles to grow on the TMD monolayer to produce the TMD composite material decorated with platinum nanoparticles.

[0017] Additionally or optionally, the step of depositing platinum nanoparticles on the TMD monolayer further comprises: (c) collecting the TMD composite material decorated with platinum nanoparticles by centrifugation.

[0018] According to preferred embodiments of the present application, the reducing agent is trisodium citrate.

[0019] It is a secondary object of the present application to provide a battery that can be used to generate hydrogen gas, which is constructed based on a TMD composite material decorated with platinum nanoparticles. The battery comprises, in terms of structure, a working electrode, which is made by coating an ink on a glassy carbon electrode and drying it in air; a reference electrode; a counter electrode; and an electrolyte, which is sulfuric acid with a concentration of about 0.5 M.

[0020] According to an embodiment of the present application, the ink is made by mixing the TMD composite material decorated with platinum nanoparticles, which is made by the method of the present application, with a solution to form a mixture, and subjecting the mixture to ultrasonic treatment, wherein the solution is composed of water, ethanol, and 5% sulfonated tetrafluoroethylene-based fluorinated polymer-copolymer dispersion liquid in a volume ratio of 4:1:0.1.

[0021] It is a third object of the present application to provide a method for generating hydrogen gas from a solution. The method comprises electrolyzing the solution in a battery constructed based on a TMD composite material decorated with platinum nanoparticles.

[0022] According to an embodiment of the present application, the solution is water.

[0023] The details of one or more embodiments of the present application are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description of the application and from the claims. BRIEF DESCRIPTION OF DRAWINGS

[0024] A more complete appreciation of the application and its advantages will be readily understood by reference to the following detailed description and the accompanying drawings, in which:

[0025] Figure 1 is a property analysis of Pt-TaS2 or Pt-TiS2 (a) AFM images of Pt-TaS2 and (b) Pt-TiS2 nanolayers, where the insets are the thickness of the selected areas of the nanolayers; (c) TEM images of Pt-TaS2 and (d) Pt-TiS2 nanolayers, where the insets are the diffraction patterns and HRTEM; (e) TEM images of Pt-TaS2-0.5 h, (f) Pt-TaS2-1 h, (g) Pt-TiS2-0.5 h, and (h) Pt-TiS2-1 h, where the insets are the diffraction patterns; (i) HRTEM images of Pt-TaS2-1 h and (j) Pt-TiS2-1 h, where the distribution of platinum nanoparticles is shown in (k) and (1), respectively. The size of 100 platinum nanoparticles was calculated using image software ImageJ, and the size distribution was generated after analyzing the data with a Gaussian function.

[0026] Figure 2 (a) is the XPS Ta 4f photoelectron spectra of TaS2 monolayer and Pt-TaS2-1h; (b) is the XPS Pt 4f photoelectron spectra of Pt-TaS2-1h; (c) is the XPS Ti 2p photoelectron spectra of TiS2 monolayer and Pt-TiS2-1h; (d) is the XPS Pt 4f spectra of Pt-TiS2-1h. All samples in XPS analysis were deposited on Si / SiO2 substrates, (e) and (f) are the Raman spectra of Pt-TaS2 and Pt-TiS2 nanomaterials, respectively, where the insets show the atomic vibration scenarios of different Raman modes in 1T TaS2 and 1T TiS2.

[0027] Figure 3 is the HER performance analysis of Pt-TaS2 or Pt-TiS2 composites, (a) and (b) are the polarization curves of (a) TaS2 and Pt-TaS2 composite and (b) TiS2 and Pt-TiS2 composite and commercial Pt / C catalyst, respectively; (c) and (d) are the Tafel plots of the materials in (a) and (b), respectively; (e) and (f) are the Nyquist plots of (e) Pt-TaS2 composite and (f) Pt-TiS2 composite, respectively, where the insets are the corresponding equivalent circuits; (g), (h) and (i) are the polarization curves of (g) Pt-TaS2-1h, (h) Pt-TiS2-1h and (i) commercial Pt / C catalyst before and after 1000 cycles, respectively; (j) is the overpotential at 10 mA / cm2of Pt-TaS2-1h, Pt-TiS2-1h or commercial Pt / C catalyst before and after 1000 cycles. 2

[0028] Figure 4 is a structural schematic diagram of a battery 100 comprising a TM D composite with platinum nanoparticle decoration according to a preferred embodiment of the present application. DETAILED DESCRIPTION

[0029] Embodiments of the present application will be described in detail below with reference to the accompanying drawings. However, it should be noted that the following detailed description and drawings are provided only to illustrate the concept of the present application and the scope of the rights of the present application is not limited to this.

[0030] 1. Definitions

[0031] In this context, an electrocatalyst refers to a catalyst that participates in an electrochemical reaction and is typically present at the surface of an electrode or is the electrode itself. An electrocatalyst can facilitate the transfer of electrons between the electrode and the reactants and / or facilitate the intermediate chemical transformations depicted by the half-reactions. Like other catalysts, an electrocatalyst can lower the activation energy required for a reaction without changing the chemical equilibrium.

[0032] ​In this document, "hydrogen evolution reaction (HER)" refers to the cathodic reaction in the electrochemical splitting of water, which reduces hydrogen ions to hydrogen gas (i.e., 2H + + 2e - → H2), which is itself a key chemical reagent and fuel. The reduction of hydrogen ions to hydrogen gas typically requires the assistance of a catalyst (e.g., platinum or the platinum nanoparticle-decorated TMD composite of the present invention).

[0033] 2. Method of manufacturing a platinum nanoparticle-decorated TMD composite

[0034] The primary object of the present invention is to provide a method of manufacturing a platinum nanoparticle-decorated TMD composite. The method comprises depositing platinum nanoparticles on a TMD monolayer in the presence of a reducing agent.

[0035] First, a TMD monolayer required for the deposition reaction is manufactured by intercalating lithium between layers and exfoliating the layered material in pieces. According to embodiments of the present invention, intercalating lithium between layers is performed in a lithium battery having a lithium foil as an anode or positive electrode and a copper foil coated with a bulk TMD on the surface as a cathode or negative electrode, and a solution composed of LiPF6, ethyl carbonate (EC), and dimethyl carbonate (DMC) as an electrolyte. When operated, the lithium battery is first discharged (discharge current: 0.025 mA, voltage: 0.9 V) to produce a lithiated bulk TMD. Next, the lithiated bulk TMD is placed in water and subjected to ultrasonic waves to exfoliate the lithiated bulk TMD into a desired TMD monolayer in pieces. According to non-essential or additional embodiments of the present invention, the TMD monolayer exfoliated into a monolayer material in pieces is recovered by centrifugation. Preferably, the TMD monolayer is collected from water using two-step centrifugation. According to embodiments of the present invention, two-step centrifugation comprises first centrifuging the exfoliated product at 3,000 rpm for 15 minutes, and then continuing centrifugation at 8,000 rpm for 15 minutes, and the precipitate after centrifugation is the TMD monolayer. Examples of the TMD monolayer suitable for use in the present invention include, but are not limited to, a tantalum disulfide monolayer, a titanium disulfide monolayer, and the like.

[0036] Next, the TMD monolayer prepared in the above manner is mixed with a solution containing a reducing agent, potassium chloroplatinate (K2PtCl4), and water, wherein the reducing agent and the potassium chloroplatinate are present in the solution in a molar ratio of about 3:2; and then the resulting mixture is subjected to a light treatment for a period of time ranging from 0.1 to 2 hours to initiate a reduction reaction to reduce the platinum (II) ions to metallic platinum nanoparticles on the TMD monolayer, i.e., to deposit platinum nanoparticles on the TMD monolayer, which is a TMD composite decorated with platinum nanoparticles. Examples of suitable reducing agents for use in the method of the present application include, but are not limited to, trisodium citrate, sodium borohydride, and YY. Preferably, the reducing agent is trisodium citrate.

[0037] According to a preferred embodiment of the present application, the light treatment is performed by irradiating the above-formed mixture with a halogen lamp to reduce the platinum (II) ions to metallic platinum (i.e., to deposit platinum on the TMD monolayer) on the TMD monolayer using the photons generated by the halogen lamp (about 150 watts). For this purpose, the above-formed mixture is irradiated with a halogen lamp for a period of time ranging from about 0.1 to 2 hours, e.g., about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2.0 hours; more preferably, the above-formed mixture is irradiated with a halogen lamp for a period of time ranging from about 0.5 to 1.5 hours, e.g., about 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, or 1.5 hours. According to embodiments of the present application, the size of the platinum nanoparticles deposited on the TMD monolayer can be controlled by adjusting the length of the light treatment (i.e., the length of the photochemical reduction reaction). In some embodiments, the above-formed mixture is irradiated with a halogen lamp for about 0.5 hours. In other embodiments, the above-formed mixture is irradiated with a halogen lamp for about 1.0 hour. According to some embodiments of the present application, the size of the platinum nanoparticles deposited on a TaS2 monolayer can increase from 0.82 nm to 1.28 nm and the size of the platinum nanoparticles deposited on a TiS2 monolayer can increase from 0.88 nm to 1.63 nm as the length of the light treatment increases from 0.5 hours to 1 hour. In addition, to avoid overheating of the reactants during the light treatment, the above reduction reaction is preferably performed under ice bath.

[0038] After the illumination treatment, the TMD composite material with platinum nanoparticle decoration produced can also be collected by centrifugation. According to embodiments of the present application, each platinum nanoparticle deposited on the TMD monolayer has a size of about 0.8 nm to 1.8 nm, such as about 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, or 1.8 nm.

[0039] 3. Producing hydrogen gas with a battery comprising a TMD composite material with platinum nanoparticle decoration

[0040] The TMD composite material with platinum nanoparticle decoration produced by the above method can itself serve as an electrocatalyst for the hydrogen evolution reaction. Therefore, a second object of the present application is to provide a battery 100 constructed with a TMD composite material with platinum nanoparticle decoration and suitable for the hydrogen evolution reaction. Referring to Figure 4 which is a schematic diagram of the structure of the battery 100 constructed to comprise a TMD composite material with platinum nanoparticle decoration. The battery 100 comprises, in structure, a working electrode 110, a reference electrode 120, a counter electrode 130, and an electrolyte 140, which is sulfuric acid with a concentration of about 0.5 M. According to embodiments of the present application, the working electrode 110 is produced by coating a layer of ink on a glassy carbon electrode and then air-drying it; the ink is produced by mixing the TMD composite material with platinum nanoparticle decoration of the present application with a solution to form a mixture, and then subjecting the mixture to ultrasonic treatment, wherein the solution is composed of water, ethanol, and 5% sulfonated tetrafluoroethylene-based fluorinated polymer-copolymer dispersion (5% Nafion) in a volume ratio of 4:1:0.1. Optionally, the battery 100 further comprises an air tube 150 for injecting nitrogen gas into the electrolyte 140 (i.e., Figure 4 bubbles beside the air tube 150).

[0041] In some embodiments of the present application, the electrocatalytic activity of the platinum nanoparticle-decorated TMD composite is evaluated by drawing a Tafel plot using the battery 100 constructed in the manner described above. The Tafel slope in the Tafel plot is an index commonly used in the relevant art to evaluate the rate and mechanism of an electrocatalytic reaction. In simple terms, the Tafel slope refers to the number of millivolts (mV) required to increase the current by a factor of 10, with the unit being mV / dec. Thus, the smaller the Tafel slope, the higher the activity of the catalyst, because a relatively small overpotential is required to achieve a high current density. According to a particular embodiment of the present application, the Tafel slope of titanium disulfide is 128 mV / dec, but the Tafel slope of the platinum nanoparticle-decorated titanium disulfide composite obtained after 0.5 hours of light treatment (i.e., Pt-TiS2-0.5h) is 82 mV / dec, and the Tafel slope of the platinum nanoparticle-decorated titanium disulfide composite obtained after 1.0 hours of light treatment (i.e., Pt-TiS2-1h) is even lower, at 55 mV / dec. Thus, it can be seen that the electrocatalytic activity of the platinum nanoparticle-decorated titanium disulfide composite obtained after 1.0 hours of light treatment (i.e., Pt-TiS2-1h) is much better than that of the titanium disulfide composite obtained after 0.5 hours of light treatment (i.e., Pt-TiS2-0.5h) or that of pure titanium disulfide (TiS2). Thus, the platinum nanoparticle-decorated TMD composite of the present application can be a better alternative to platinum / carbon catalysts required for commercial hydrogen evolution applications.

[0042] According to embodiments of the present application, the battery constructed as described above can be used to electrolyze a solution (e.g., water) to produce hydrogen gas.

[0043] The present application will be described in accordance with embodiments, which are provided by way of example only, and the scope of the present application is not limited to the disclosed embodiments.

[0044] Examples

[0045] Materials and Methods

[0046] Material Analysis

[0047] Example 1: Fabrication and Analysis of Pt-TiS2 or Pt-TaS2 Composite

[0048] 1.1 TiS2 Nanosheets or TaS2 Nanosheets

[0049] This example is a method for producing TiS2nanosheets or TaS2nanosheets by electrochemically intercalating lithium between layers and exfoliating in water. To electrochemically intercalate lithium, a lithium battery was constructed to perform this step. First, a copper foil coated with TiS2or TaS2powder was used as a cathode, and a lithium foil was used as an anode, with the anode and cathode separated from each other by polypropylene (PP). Then, a 1 M LiPF6solution was dissolved in a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) at a volume ratio of 1:1 to form the electrolyte required for the lithium battery.

[0050] Next, the lithium battery was discharged (the constant current required for discharge was 0.025 mA, and the cutoff voltage was 0.9 V) to produce lithiated TiS2or TaS2(i.e., Li x TiS2or Li x TaS2). The Li x TiS2or Li x TaS2) was carefully removed and placed in deionized water and subjected to ultrasonic oscillation to exfoliate the Li x TiS2or Li x TaS2into TiS2nanosheets or TaS2nanosheets. The resulting TiS2nanosheets or TaS2nanosheets were collected by two-step centrifugation, washed with deionized water, and then dried to remove residual lithium ions or other possible contaminants such as electrolyte. The two-step centrifugation was performed at 3,000 rpm for 15 minutes and then at 8,000 rpm for another 15 minutes, and the precipitate obtained by centrifugation was the TiS2nanosheets or TaS2nanosheets.

[0051] Next, the atomic structure of the resulting TiS2nanosheets or TaS2nanosheets was observed using a high-angle annular dark-field scanning electron microscope, and the surface charge of the nanosheets was evaluated by measuring the Zeta potential. The results showed that the resulting TiS2nanosheets or TaS2nanosheets could be uniformly dispersed in water, presumably because the resulting TiS2nanosheets or TaS2nanosheets had a negative surface charge. The Zeta potential of the TiS2nanosheets was -63 mV, and the Zeta potential of the TaS2nanosheets was -56.8 mV.

[0052] 1.2 Pt-TiS2or Pt-TaS2composite materials

[0053] The TiS2or TaS2monolayer (1 mL) obtained from Example 1.1 was mixed with trisodium citrate (0.5 mM) and potassium chloroplatinate (0.2 mM) in water to form a solution of about 18 mL. The reduction reaction was initiated by irradiating the solution with a 150 W halogen lamp while the reaction vessel was kept in an ice bath to avoid overheating. The irradiation was continued for about 0.5 or 1 h and the effect of the reduction time on the appearance and hydrogen evolution performance of the resulting composite was observed. During the irradiation, the color of the reaction solution changed from purple-gray to yellow-gray for the growth of Pt nanoparticles on the TaS2monolayer, and from gray to light yellow-gray for the growth of Pt nanoparticles on the TiS2monolayer. After the irradiation, the Pt-TiS2or Pt-TaS2composite was recovered by centrifugation and washed with water.

[0054] Figure 1 is a photograph of the structure and appearance of the Pt-TiS2or Pt-TaS2composite taken by atomic force microscopy (AFM) or transmission electron microscopy (TEM). The AFM photograph confirmed that the individual thickness of the Pt-TiS2or Pt-TaS2composite was less than 1 nm (see insets in Figure 1(a) and 1(b) ). The TEM photograph showed that both the Pt-TiS2and Pt-TaS2composite had a smooth surface (see insets in Figure 1(c) and 1(d) ). The selected area electron diffraction (SAED) pattern of the selected area in the photograph showed that there were six bright spots on the (110) plane on the outside and the weaker spots were on the (100) plane on the inside (see insets in Figure 1(c) and 1(d) ). The lattice spacing of the (110) plane of TaS2and TiS2was about 1.7 A (see insets in Figure 1(c) and 1(d) ). Figures 1(e)-1(h) The Pt-TiS2or Pt-TaS2composite obtained after 0.5 h or 1 h irradiation was designated as Pt-TaS2-0.5h, Pt-TaS2-1 h, Pt-TiS2-0.5h, and Pt-TiS2-1 h, respectively. The results showed that the density of the platinum metal nanoparticles (Pt NPs) deposited on the TiS2or TaS2monolayer increased with increasing irradiation time. The SAED pattern of both Pt-TaS2-0.5h and Pt-TaS2-1 h showed the typical hexagonal pattern of the TaS2layer with six spots on the (110) plane on the outside and six spots on the (100) plane on the inside (see insets in Figures 1(e)-1(f)(See the illustration in the figure). Regarding the density of platinum nanoparticles (Pt NPs) deposited on the TiS2 monolayer (see Figure 1(h)), in addition to the deposition on the (110) and (100) planes observed from the SAED mode, there are also continuous ring-shaped deposits of platinum nanoparticles on the (111) plane. This is confirmed by high-resolution TEM images of Pt-TaS2-1h (see Figure 1(i)) and Pt-TiS2-1h (see Figure 1(j)), where a d-spacing of 2.2 Å can be measured on the Pt(111) plane (see the illustration in the figure). Figure 1(i) and 1(j) (See the illustration in Figure 1(k)). Analysis of 100 platinum particles revealed that the average size of Pt NPs for Pt-TaS2-1h and Pt-TiS2-1h was approximately 1.28 nm (see Figure 1(k)) and 1.63 nm, respectively, and the Pt NPs were uniformly distributed throughout the entire TaS2 or TiS2 monolayer.

[0055] Next, the chemical composition of pure TiS2 monolayer, pure TaS2 monolayer, or the Pt-TiS2 or Pt-TaS2 composite material of the present invention was analyzed by X-ray photoelectric imaging (XPS), and the results are shown in Figure 2. In Figure 2(a), the double peak at 24.0-25.9 eV is Ta4f originating from TiS2. 7 / 2-5 / 2 Furthermore, oxidized Ta₂O₅ can be detected on the monolayer. After Pt NPs are deposited on the TaS₂ monolayer, the aforementioned peak shifts to a position with a lower binding energy. A similar peak shift also appears on the TiS₂ monolayer with deposited Pt NPs (see Figure 2(c)), indicating electron transfer to the TiS₂ monolayer. Regarding the 4f energy spectrum of platinum (see...), Figure 2(b) and 2(d) In both the Pt-TaS2-1h and Pt-TiS2-1h composite materials, three different valences of platinum ions (i.e., Pt...) were observed. δ+ Pt 2+ Pt 4+ ), of which Pt δ+ This is the most important price level. However, there is no platinum (Pt) with a zero price level. 0 This shift is likely due to the reaction between the TMD material and Pt NPs, which causes electrons to transfer from the Pt NPs to the TMD layer. After Pt NPs are deposited on TaS2 and TiS2, this trend of the Ta4f and Ti2p peaks shifting to lower binding energy positions can also be observed in the S2p spectra of TaS2 and TiS2.

[0056] Next, Raman spectroscopy was used to investigate the electronic structure of the TaS2 and TiS2 monolayers. As shown in Figure 2(e), the stripped TaS2 monolayer has three main characteristic peaks, located at 241 cm⁻¹. -1 301cm-1 and 378cm -1 , respectively corresponding to E of 1T TaS2 1g (Vibration of the S atom in the plane), E 1 2g (plane vibrations of Ta and S atoms), and A 1g (Out-of-plane vibrational mode of S atoms). For the exfoliated TiS2 monolayer (Fig. 2(f)), two characteristic peaks can be observed, at 225 cm⁻¹. -1 and 334cm -1 , respectively corresponding to E of 1T TiS2 g (The plane vibration of the S atom) and A 1g (Out-of-plane vibration of S atoms) mode. These 1T phase results are consistent with the HAAD-STEM images of stripped TaS2 or TiS2 monolayers captured by the HAADF-STEM imaging system.

[0057] Example 2: Hydrogen evolution reaction efficiency of Pt-TiS2 or Pt-TaS2 composite materials from Example 1

[0058] In this embodiment, the electrocatalytic performance (i.e., HER performance) of Pt-TiS2 or Pt-TaS2 composite materials prepared at different growth times was evaluated using linear voltammetry (LSV) in a 0.5 M H2SO4 electrolyte. The results are shown in Figure 3.

[0059] like Figures 3(a)-3(b) As shown, compared to pure TaS2 or TiS2 monolayers, the composite material with Pt NPs deposited on it exhibits higher electrocatalytic activity, which can be achieved by a current density of 10 mA / cm². 2 The decrease in overpotential on the polarization curves is confirmed. Furthermore, Tafel plots or DC corrosion analysis diagrams also show that after Pt NPs deposition, the Tafel slope decreases from 128 mV / dec for TaS2 to 62 mV / dec for Pt-TaS2-0.5h and 50 mV / dec for Pt-TaS2-1h (see Figure 3(c)). Similar results are observed on the Pt-TiS2 composite material, where the Tafel slope decreases from 128 mV / dec for TiS2 to 82 mV / dec for Pt-TiS2-0.5h and 55 mV / dec for Pt-TiS2-1h (see Figure 3(d)).

[0060] Next, electrochemical impedance spectroscopy was used to evaluate the charge transfer impedance of pure TaS2 or TiS2 monolayers, as well as Pt-TiS2 or Pt-TaS2 composites. Figures 3(e)-3(f)The charge transfer resistance of Pt-TaS2-1h is the smallest compared to Pt-TaS2-0.5h and pure TaS2layer, as shown by the circuit and the resulting Nyquist plot (Figure 3(e)), which confirms that Pt-TaS2-1h can effectively transfer charge during HER. Similar results are also observed for Pt-TiS2-1h composite, where the charge transfer resistance of Pt-TiS2-1h is the smallest compared to Pt-TiS2-0.5h and pure TiS2layer (Figure 3(f)). These results are consistent with the results of polarization curves (Figure 3(g)) and Tafel plots (Figure 3(h)) of these materials. Figures 3(a)-3(b) ) and Tafel plots ( Figures 3(c)-3(d) ) of these materials.

[0061] The pathway of HER mechanism can be elucidated by analyzing the Tafel slope. It is known that HER reaction in acidic solution involves three main steps (see Zhu et al., Chem. Rev. 120 (2020) 851-918). The first step is called Volmer reaction (H3O + + catalyst + e - → catalyst-H* + H2O, 120 mV / dec), where an adsorbed hydrogen atom (H + ) forms an adsorbed hydrogen intermediate (H*) on the catalyst surface after absorbing an electron (e - ). The second step is called Heyrovsky reaction (H3O + + catalyst-H* + e - → H2 + H2O + catalyst, 40 mV / dec), where catalyst-H* reacts with another hydrogen atom and electron to produce hydrogen gas (H2). The third step is called Tafel reaction (2 catalyst-H* → H2 + 2 catalyst, 30 mV / dec), where two catalyst-H* combine to form a hydrogen molecule. According to Figures 3(c)-3(d)The reaction mechanism of TaS2nanolayer is related to the Volmer reaction. On the contrary, Pt-TaS2-0.5h and Pt-TaS2-1h follow the Volmer-Heyrovsky reaction, where the Tafel slope of TaS2nanolayer is 128 mV / dec, while the Tafel slopes of Pt-TaS2-0.5h and Pt-TaS2-1h are 62 mV / dec and 50 mV / dec, respectively. The homo-coupling effect between TaS2nanolayer and Pt NPs will shift the rate-determining step from the electrochemical hydrogen adsorption step of TaS2nanolayer to the electrochemical hydrogen desorption step of Pt-TaS2composite. Similar effect will also occur in Pt-TiS2composite. TiS2nanolayer follows the Volmer reaction with a Tafel slope of 138 mV / dec, while Pt-TiS2-0.5h and Pt-TiS2-1h follow the Volmer-Heyrovsky reaction with Tafel slopes of 82 mV / dec and 55 mV / dec, respectively.

[0062] In addition, the cycle stability is also an important issue to be considered when the nanocomposite is applied in practice. Therefore, the battery stability of the battery containing Pt-TaS2or Pt-TiS2composite and the battery using commercial Pt / C catalyst after 1000 cycles was investigated in this embodiment, and the results are shown in Figures 3(g)-3(h) As shown in the figure, the HER performance of the battery containing Pt-TaS2-1hor Pt-TiS2-1hremains similar to the initial performance after 1000 cycles, and the cathode current density is almost not reduced, which represents excellent battery stability. On the contrary, the cathode current density of the battery using commercial Pt / C catalyst is obviously reduced after 1000 cycles (Figure 3(i)). After 1000 cycles, the overpotential of the battery containing Pt-TaS2-1hor Pt-TiS2-1hat a current density of 10 mA / cm 2 is increased by about 2% and about 3%, respectively, but the overpotential of the battery using commercial Pt / C catalyst is increased by about 64% (Figure 3(j)). If the electrocatalytic activity of Pt-TaS2-1h and Pt-TiS2-1h for HER is compared with that of known TaS2or TiS2-based catalysts, the electrocatalytic activity of Pt-TaS2-1h and Pt-TiS2-1his obviously superior to that of the currently known TaS2or TiS2-based catalysts. In summary of the current results, although the electrocatalytic activity of Pt-TaS2-1h and Pt-TiS2-1his slightly lower than that of the battery using commercial Pt / C catalyst, it exhibits more excellent cycle stability.

[0063] In summary, the present application utilizes an environmentally friendly electrochemical reduction method (i.e., without using high temperature, corrosive chemicals or other extreme conditions) to deposit metallic platinum with a size of about 1.2 nm to 1.6 nm onto a TaS2 or TiS2 monolayer to form a composite material. In addition, the size of the platinum nanoparticles deposited on the composite material can be adjusted by adjusting the length of light exposure, which is also related to the subsequent performance of the composite material on HER. In addition, the battery containing the Pt-TaS2-1h or Pt-TiS2-1h composite material of the present application not only has an electrocatalytic activity close to that of a battery using a commercial Pt / C catalyst, but also has a cycle stability far superior to that of a battery using a commercial Pt / C catalyst after 1000 cycles.

[0064] Although the specific embodiments of the present application are disclosed in the above embodiments, they are not intended to limit the present application, and those skilled in the art can make various modifications and modifications without departing from the principles and spirits of the present application. Therefore, the protection scope of the present application shall be defined by the appended patent claims.

Claims

1. A battery to generate hydrogen gas, characterized by, Comprise: a working electrode; a reference electrode; a pair of electrodes; and an electrolyte, which is sulfuric acid with a concentration of about 0.5 M; wherein: the working electrode, the reference electrode and the pair of electrodes are inserted into the electrolyte; and the working electrode comprises a glassy carbon electrode and a transition metal dichalcogenide monolayer formed on a surface of the glassy carbon electrode, the transition metal dichalcogenide monolayer being decorated with platinum nanoparticles.

2. The battery for generating hydrogen gas according to claim 1, wherein each platinum nanoparticle has a size between 0.8 nm and 1.8 nm; and the transition metal dichalcogenide monolayer is a tantalum disulfide monolayer or a titanium disulfide monolayer.

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