Preparation method of Ni0.85Se / NiMoOx heterojunction catalyst based on hydrogen evolution reaction in alkaline environment

Abstract

The invention discloses a preparation method of a Ni0. 85Se / NiMoOx heterojunction catalyst based on hydrogen evolution reaction in an alkaline environment. The preparation method comprises the following steps: S1, producing NiMoO4 nanorods on a foamed nickel substrate through hydrothermal reaction; s2, a nickel-molybdenum metal oxide is introduced, and NiMoO-NH is formed by loading a Ni (OH) 2 nanosheet on the NiMoO4 nanorod; and S3, synthesizing the Ni < 0.85 > Se / NiMoOx heterojunction catalyst through selenylation reduction and ion exchange. The Ni0.85Se / NiMoOx heterojunction catalyst obtained by the invention has a nanosheet-coated nanorod multilevel structure, abundant active sites and sufficient substance transfer, and meanwhile, the combination of crystalline Ni0.85Se and amorphous NiMoOx adjusts the electronic structure of the surface and interface of the catalyst, optimizes the adsorption and desorption of reaction intermediates and accelerates HER kinetics.

Description

Technical Field

[0001] The present invention relates to the technical field of water electrolysis and hydrogen evolution reaction catalysis, and in particular to a Ni-based hydrogen evolution reaction in an alkaline environment. 0.85 Se / NiMoO x A method for preparing a heterojunction catalyst. Background Art

[0002] Water electrolysis is a green and environmentally friendly technology that is expected to solve energy and ecological problems worldwide, but its effectiveness is constrained by the slow reaction kinetics of the anode oxygen evolution reaction (OER) and the cathode hydrogen evolution reaction (HER). In recent years, transition metal-based electrocatalysts have become a hot topic in the research of water electrolysis and hydrogen production catalysts due to their low price and abundant reserves. In particular, selenides in transition metal sulfide compounds have the characteristics of high conductivity, adjustable d electron structure and good HER activity, and are expected to become a substitute for the precious metal Pt in water electrolysis and hydrogen production. The results show that Ni x Se y With proper d electron configuration, Ni x Se y The Se atoms at the edge are HER active sites, such as NiSe nanosheets, Ni 0.85 Se nanosheets, etc. Therefore, people have been working hard to develop multi-metal nickel-based selenide electrocatalysts and selenide materials of different forms through different cation doping and crystal phase engineering strategies. 0.33 Co 0.67 Se 2 / CFP nanowire, Ni 0.89 Co 0.11 Se 2 MNSN / NF porous nanosheets and Co similar to loofah network 0.6 Ni 0.4 Se 2 -LN, etc. Although these catalysts significantly increase the number of edge active sites, they are still limited by the slow water dissociation step under alkaline conditions, and the catalytic activity needs to be improved. In addition, under long-term testing conditions, these nanosheets or nanoparticles tend to agglomerate, resulting in deformation, decreased stability and electrocatalytic activity.

[0003] H 2 The dissociative adsorption energy of O on the catalyst and H * and OH -The adsorption energy of is one of the three key factors affecting the alkaline HER process. Accordingly, in order to overcome the problem of sluggish alkaline HER kinetics, efficient HER electrocatalysts should be designed according to the following principles: low water dissociation barrier and appropriate hydrogen binding energy and hydrogen-oxygen binding energy (HBEs and OHBEs). However, due to structural relationships, these intrinsic functional requirements are difficult to be met simultaneously on single-component electrocatalysts. On the contrary, when two different components contact to form a heterostructure, the atomic configuration is reorganized and the electronic structure is adjusted near the heterointerface. Liu et al. constructed an amorphous / crystalline CoBO x / NiSe heterostructure for efficient water electrolysis (HER: 14.5mV@10mA·cm -2 , OER: 229.1mV@10mA·cm -2 ). Composite electrocatalysts composed of different functional components can provide potential for fine-tuning the water dissociation kinetics, H* and OH adsorption and desorption capabilities simultaneously, which is beneficial to the alkaline HER process. It is reported that the hybridization of nickel-based alloys with metal oxides has high efficiency in alkaline HER, which is due to the high H deposition rate of nickel-based alloys. 2 In order to improve the activity of selenide catalysts, Mo-doped NF@Mo-Ni 0.85 SeNSs and NiFe(OH) x Coupled (Ni,Fe)Se 2 NSs are stable and efficient catalysts. 2 -NiMoO 4 The heterojunction and CoFe-LDH on NiSe nanosheets are also stable and efficient catalysts. By constructing the synergistic effect of interface and heterostructure, the electron transfer, active sites and catalytic activity can be effectively regulated.

[0004] Therefore, Ni-Mo metal oxide composite Ni 0.85 Se will show excellent HER activity, so this application designed and synthesized Ni nanosheets coated with nanorods. 0.85 Se / NiMoO x The catalyst is more suitable for alkaline hydrogen evolution. Summary of the invention

[0005] The present invention is based on the Ni-based hydrogen evolution reaction in an alkaline environment 0.85 Se / NiMoO x A method for preparing a heterojunction catalyst comprises:

[0006] S1. Production of NiMoO by hydrothermal reaction on nickel foam substrate 4 Nanorods;

[0007] S2, the introduction of nickel-molybdenum metal oxide, by NiMoO 4 Ni(OH) loaded on nanorods 2 Nanosheets form NiMoO-NH;

[0008] S3, synthesis of Ni by selenization reduction and ion exchange 0.85 Se / NiMoO x Heterojunction catalyst.

[0009] Preferably, the nickel foam substrate in S1 is pretreated; the pretreatment includes removing surface oxides and oil stains of the nickel foam substrate, specifically including: immersing the nickel foam in acetone, 3M HCl, water, and ethanol for ultrasonic cleaning for 12-15 minutes, and placing the pretreated nickel foam in anhydrous ethanol for standby use.

[0010] Preferably, the NiMoO in the S2 4 The synthesis of nanorods specifically includes the following steps:

[0011] S2.1.1. Take a 50mL clean beaker and add 36-40mL of H 2 O, then weigh 0.4-0.5g Ni(NO 3 ) 2 6H 2 O, 0.4-0.5g (NH 4 ) 6 Mo 7 O 24 ·4H 2 O and 0.1-0.2 g NH 4 F;

[0012] S2.1.2, add to the beaker in order and stir until the solution becomes clear and transparent;

[0013] S2.1.3. Transfer the solution to a 50 mL reactor liner and place the pretreated nickel foam in the sealed reactor in a hot air oven for reaction;

[0014] S2.1.4. After the reaction, the mixture was cooled to room temperature naturally, washed with ethanol and water for several times, and dried in an electric hot air oven at 60-65°C to obtain NiMoO 4 Nanorods.

[0015] Preferably, the Ni(NO 3 ) 2 6H 2 The nickel nitrate concentration of O is 0.04-0.05 mol / L; the (NH 4 ) 6 Mo7 O 24 ·4H 2 The concentration of ammonium molybdate O is 0.01-0.02 mol / L; the NH 4 The ammonium fluoride concentration of F is 0.1-0.15 mol / L.

[0016] Preferably, the sealed reactor in S2.1.3 is reacted in a hot air oven at 5-8°C min -1 The temperature was raised at a rate of 160-165°C and the hydrothermal reaction was carried out for 6-6.5 hours.

[0017] Preferably, the synthesis of NiMoO-NH in S2 specifically comprises the following steps:

[0018] S2.2.1. Through the precursor NiMoO 4 Nanorods are used as substrate to introduce Ni(OH) 2 The nanosheets formed a wrinkled structure of NiMoO-NH nanorods coated with nanorods;

[0019] S2.2.2. Take a precursor NiMoO 4 The nanorods were immersed in 36-38 mL of a solution containing 40-42 mM nickel nitrate, 160-165 mM urea, and 240-245 mM ammonium fluoride;

[0020] S2.2.3, transfer to the Teflon liner of a 50 mL high-pressure reactor, place the sealed reactor in an electric blast oven, perform hydrothermal reaction at 160-165°C for 6-6.5 hours, and then naturally cool to room temperature;

[0021] S2.2.4. Wash with ethanol and water several times, and dry the obtained NiMoO-NH in an electric heated forced air oven at 60-65°C overnight.

[0022] Preferably, Ni in S3 0.85 Se / NiMoO x The synthesis comprises the following steps:

[0023] S3.1. Take the hydrothermal product NiMoO-NH, weigh 0.15-0.18 g of Se powder, pour it into a beaker filled with 36-38 mL of ultrapure water and stir evenly;

[0024] S3.2, weigh 0.3-0.35g NaBH 4 Pour the powder into a beaker and stir until the selenium powder is completely dissolved and then transfer to the liner of a 50-55mL reactor;

[0025] S3.3, immerse NiMoO-NH in the solution and seal the reactor, place the sealed reactor in an electric blast oven, perform hydrothermal reaction at 160-165°C for 6-6.5 hours and then naturally cool to room temperature;

[0026] S3.4, wash with ethanol and water several times, and finally dry in an electric hot air oven at 60-65℃ overnight, and cool naturally to obtain black Ni 0.85 Se / NiMoO x catalyst.

[0027] Preferably, 0.15-0.18 g of Se powder is weighed in S3.1, poured into a beaker filled with 36-38 mL of ultrapure water and stirred evenly, and the Se powder is 2-2.2 mmol.

[0028] Compared with the prior art, the technical solution of this application has the following technical effects:

[0029] The Ni of the present invention 0.85 Se / NiMoO x The heterojunction catalyst has a multi-level structure of nanosheets encapsulating nanorods, abundant active sites, and sufficient material transfer. 0.85 Se and amorphous NiMoO x The combination regulates the electronic structure of the catalyst surface interface, optimizes the adsorption and desorption of reaction intermediates, and accelerates HER kinetics.

[0030] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application so that it can be implemented in accordance with the contents of the specification, and to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the following is a detailed description of the preferred embodiments of the present application in conjunction with the accompanying drawings as follows.

[0031] Based on the detailed description of the specific embodiments of the present application in combination with the accompanying drawings below, those skilled in the art will become more aware of the above and other objects, advantages and features of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings without creative work. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, each element or part is not necessarily drawn according to the actual scale.

[0033] Figure 1The Ni based hydrogen evolution reaction in alkaline environment of the present invention 0.85 Se / NiMoO x Overall flow chart of the heterojunction catalyst preparation method

[0034] Figure 2 The Ni based hydrogen evolution reaction in alkaline environment of the present invention 0.85 Se / NiMoO x Heterojunction Catalyst Preparation Method NiMoO 4 Flow chart of nanorod synthesis;

[0035] Figure 3 The Ni based hydrogen evolution reaction in alkaline environment of the present invention 0.85 Se / NiMoO x Synthesis flow chart of NiMoO-NH for heterojunction catalyst preparation method;

[0036] Figure 4 The Ni based hydrogen evolution reaction in an alkaline environment of the present invention 0.85 Se / NiMoO x Ni heterojunction catalyst preparation method 0.85 Se / NiMoO x Synthesis flow chart of

[0037] Figure 5 The Ni based hydrogen evolution reaction in alkaline environment of the present invention 0.85 Se / NiMoO x X-ray diffraction pattern of heterojunction catalyst preparation method;

[0038] Figure 6 The Ni based hydrogen evolution reaction in alkaline environment of the present invention 0.85 Se / NiMoO x SEM image of the heterojunction catalyst preparation method;

[0039] Figure 7 The Ni based hydrogen evolution reaction in alkaline environment of the present invention 0.85 Se / NiMoO x Ni heterojunction catalyst preparation method 0.85 Se / NiMoO x Scanning electron microscope image of

[0040] Figure 8 The Ni based hydrogen evolution reaction in alkaline environment of the present invention 0.85 Se / NiMoO x Ni heterojunction catalyst preparation method 0.85 Se / NiMoO x High-resolution electron microscopy images of

[0041] Fig. 9The Ni based hydrogen evolution reaction in alkaline environment of the present invention 0.85 Se / NiMoO x Ni heterojunction catalyst preparation method 0.85 Se / NiMoO x XPS spectrum of

[0042] Fig.10 The Ni based hydrogen evolution reaction in alkaline environment of the present invention 0.85 Se / NiMoO x XPS spectrum comparison of heterojunction catalyst preparation methods;

[0043] Fig.11 The Ni based hydrogen evolution reaction in alkaline environment of the present invention 0.85 Se / NiMoO x Comparison of hydrogen evolution using heterojunction catalyst preparation methods;

[0044] Fig.12 The Ni based hydrogen evolution reaction in alkaline environment of the present invention 0.85 Se / NiMoO x Cyclic voltammetry curve of the heterojunction catalyst preparation method;

[0045] Fig.13 The Ni based hydrogen evolution reaction in alkaline environment of the present invention 0.85 Se / NiMoO x Stability test diagram of the heterojunction catalyst preparation method. DETAILED DESCRIPTION

[0046] To make the purpose, technical scheme and advantages of the embodiment of the present application clearer, the technical scheme in the embodiment of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiment of the present application. Obviously, the described embodiment is a part of the embodiment of the present application, rather than all of the embodiments. In the following description, specific details such as specific configuration and components are provided only to help fully understand the embodiments of the present application. Therefore, it should be clear to those skilled in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. In addition, for clarity and brevity, the description of known functions and structures is omitted in the embodiment.

[0047] It should be understood that the references to "one embodiment" or "this embodiment" throughout the specification mean that the specific features, structures, or characteristics associated with the embodiment are included in at least one embodiment of the present application. Therefore, the references to "one embodiment" or "this embodiment" appearing throughout the specification do not necessarily refer to the same embodiment. In addition, these specific features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0048] In addition, the present application may repeat reference numerals and / or letters in different examples. This repetition is for the purpose of simplicity and clarity, and does not in itself indicate the relationship between the various embodiments and / or settings discussed.

[0049] The term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, B exists alone, and A and B exist at the same time. The term " / and" in this article describes another type of association object relationship, indicating that there can be two relationships. For example, A / and B can mean: A exists alone, and A and B exist alone. In addition, the character " / " in this article generally indicates that the previous and next associated objects are in an "or" relationship.

[0050] The term "at least one" in this article is merely a description of the association relationship of associated objects, indicating that there may be three relationships. For example, at least one of A and B can mean: A exists alone, A and B exist at the same time, and B exists alone.

[0051] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusions.

[0052] Example 1

[0053] This example mainly describes the Ni based hydrogen evolution reaction in an alkaline environment. 0.85 Se / NiMoO x Detailed preparation methods of heterojunction catalysts, such as Figure 1 As shown, including:

[0054] S1. Production of NiMoO by hydrothermal reaction on nickel foam substrate 4 Nanorods;

[0055] S2, the introduction of nickel-molybdenum metal oxide, by NiMoO 4 Ni(OH) loaded on nanorods 2 Nanosheets form NiMoO-NH;

[0056] S3, synthesis of Ni by selenization reduction and ion exchange 0.85 Se / NiMoO x Heterojunction catalyst.

[0057] Further, the nickel foam substrate in S1 is pretreated; the pretreatment includes removing the surface oxide and oil stains of the nickel foam substrate, specifically including: immersing the nickel foam in acetone, 3M HCl, water, and ethanol for ultrasonic cleaning for 15 minutes, and placing the pretreated nickel foam in anhydrous ethanol for standby use.

[0058] Further, if Figure 2 As shown, the NiMoO in S2 4 The synthesis of nanorods specifically includes the following steps:

[0059] S2.1.1. Take a 50mL clean beaker and add 36mL of H 2 O, then weigh 0.4187gNi(NO 3 ) 2 6H 2 O, 0.4449 g (NH 4 ) 6 Mo 7 O 24 ·4H 2 O and 0.1333 g NH 4 F;

[0060] S2.1.2, add to the beaker in order and stir until the solution becomes clear and transparent;

[0061] S2.1.3, transfer the solution to a 50 ml reactor liner and place the pre-treated nickel foam 1*5 cm 2 In the process, the sealed reactor is placed in a hot air blast oven for reaction;

[0062] S2.1.4. After the reaction, the mixture was cooled to room temperature naturally, washed with ethanol and water for several times, and dried in an electric hot air oven at 60°C. 4 Nanorods.

[0063] Further, the Ni(NO 3 ) 2 6H 2 The nickel nitrate concentration of O is 0.04 mol / L; the (NH 4 ) 6 Mo 7 O 24 ·4H 2 The concentration of ammonium molybdate of O is 0.01 mol / L; the NH 4 The ammonium fluoride concentration of F is 0.1 mol / L.

[0064] Further, the sealed reactor in S2.1.3 is placed in a hot air oven for reaction at 5°C min-1 The temperature was raised at a rate of 100 °C and the hydrothermal reaction was carried out at 160 °C for 6 hours.

[0065] Further, if Figure 3 As shown, the synthesis of NiMoO-NH in S2 specifically includes the following steps:

[0066] S2.2.1. Through the precursor NiMoO 4 Nanorods are used as substrate to introduce Ni(OH) 2 The nanosheets formed a wrinkled structure of NiMoO-NH nanorods coated with nanorods;

[0067] S2.2.2. Take a precursor NiMoO 4 The nanorods were immersed in 36 mL of a solution containing 40 mM nickel nitrate, 160 mM urea, and 240 mM ammonium fluoride;

[0068] S2.2.3, transfer to the Teflon liner of a 50 mL high-pressure reactor, place the sealed reactor in an electric blast oven, perform hydrothermal reaction at 160°C for 6 hours, and then naturally cool to room temperature;

[0069] S2.2.4. Wash with ethanol and water several times and dry in an electric heated forced air oven at 60 °C overnight to obtain NiMoO-NH.

[0070] Further, if Figure 4 As shown, the Ni in S3 0.85 Se / NiMoO x The synthesis comprises the following steps:

[0071] S3.1. Take the hydrothermal product NiMoO-NH and weigh 0.1579 g of Se powder into a beaker containing 36 mL of ultrapure water and stir evenly;

[0072] S3.2, weigh 0.3026g NaBH 4 Pour the powder into a beaker and stir until the selenium powder is completely dissolved and then transfer to the liner of a 50 mL reactor;

[0073] S3.3, immerse NiMoO-NH in the solution and seal the reactor, place the sealed reactor in an electric blast oven, perform hydrothermal reaction at 160°C for 6 hours and then naturally cool to room temperature;

[0074] S3.4, washed with ethanol and water several times, and finally dried in an electric blast oven at 60°C overnight, and cooled naturally to obtain black Ni 0.85 Se / NiMoO x catalyst.

[0075] Furthermore, 0.1579 g of Se powder was weighed in S3.1, poured into a beaker containing 36 mL of ultrapure water and stirred evenly, wherein the Se powder was 2 mmol.

[0076] This example describes Ni 0.85 Se / NiMoO x Specific method for preparing heterojunction catalyst, Ni 0.85 Se / NiMoO x The heterojunction catalyst has a multi-level structure of nanosheets encapsulating nanorods, abundant active sites, and sufficient material transfer. 0.85 Se and amorphous NiMoO x The combination regulates the electronic structure of the catalyst surface interface, optimizes the adsorption and desorption of reaction intermediates, and accelerates HER kinetics.

[0077] Example 2

[0078] This example describes in detail the Ni based hydrogen evolution reaction in an alkaline environment. 0.85 Se / NiMoO x Morphological characterization test and verification of heterojunction catalysts, including:

[0079] like Figure 5 As shown in the figure, the chemical composition and crystal structure of the catalyst were tested by XRD. 4 Similar to the crystal structure of NiMoO-NH catalyst, the diffraction peaks clearly show characteristic diffraction peaks at 26.5°, 27.1°, and 33.7°, corresponding to the distribution of NiMoO 4 phase (220), (11-2) and (22-2) planes, and NiMoO 4 The standard PDF card has a good match, proving that the hydrothermal reaction product contains nickel molybdate; the diffraction peaks of the nickel hydroxide phase generated by the second step of hydrothermal reaction are weak, and the characteristic diffraction peaks at 33.1°, 38.6° and 52.1° correspond to Ni(OH) 2 phase (110), (011) and (012) planes, and Ni(OH) 2 The standard PDF card matches well, proving that the second step hydrothermal reaction synthesized nickel hydroxide nanosheets while retaining NiMoO 4 phase; after selenization, Ni 0.85 Se / NiMoO x The diffraction peaks of the catalyst clearly show characteristic diffraction peaks at 33.4°, 44.9°, 50.4° and 60.2°, corresponding to Ni 0.85 Se phase (101), (102), (110) and (103) planes, and Ni 0.85 Se standard PDF card matching, at the same time, the selenized Ni0.85 Se / NiMoO x The catalyst did not detect the species characteristic peaks of nickel-molybdenum oxide; Figure 5 The diffraction peaks at 44.5°, 51.8°, and 76.3° belong to the Ni substrate.

[0080] NiMoO was characterized by field emission scanning electron microscopy. 4 , NiMoO-NH and Ni 0.85 Se / NiMoO x The catalyst was tested, e.g. Figure 6 As shown, NiMoO synthesized by hydrothermal reaction 4 catalyst( Figure 6 ab) The surface presents a nanorod array structure with compact arrangement and a smooth and flat surface.

[0081] After the second hydrothermal reaction, the nanorods on the surface of the NiMoO-NH catalyst were completely covered by the wrinkles of the nanosheets, and the nanorods formed by the nanosheets grew out, and the surface of the nanosheets was smooth and flat ( Figure 6 cd), indicating that nickel hydroxide nanosheets were successfully grown.

[0082] After selenization, Ni 0.85 Se / NiMoO x The catalyst surface becomes rougher and presents a porous nanosheet structure, with nanoparticles forming on the surface of the nanosheet ( Figure 6 ef).

[0083] The nanorods coated with nanosheets showed a fluffy and porous structure after selenization, and tiny nanowires and nanoparticles grew on the surface of the nanorods, such as Figure 7 As shown ( Figure 7 ab), through Figure 7 It can be seen that this hierarchical structure is conducive to exposing more active sites and promoting electrolyte diffusion.

[0084] From Ni 0.85 Se / NiMoO x High-resolution transmission electron microscopy images of the catalyst, such as Figure 8 As shown, Figure 8 a It can be seen that the catalyst consists of two parts, crystalline and amorphous, which form a heterogeneous interface, which is beneficial to regulate the Ni 0.85 Se / NiMoO x The electronic structure of the catalyst promotes the adsorption and desorption process of intermediates during the electrocatalytic HER process.

[0085] The lattice fringe spacings of the crystalline state are 0.270nm and 0.180nm, corresponding to Ni 0.85The (101) and (110) crystal planes of Se are consistent with the XRD results; combined with the results, it is shown that the catalyst is composed of crystalline Ni 0.85 Se in amorphous NiMoO x It consists of two parts, as shown in the transmission electron microscopy image ( Figure 8 b) shows that the catalyst is composed of nanoparticles, and its corresponding selected area electron diffraction pattern shows three diffraction rings ( Figure 8 c), corresponding to Ni 0.85 The (101), (110) and (103) crystal planes of Se are consistent with the HRTEM results. Figure 8 d~i show that the four elements Ni, Mo, O, and Se are evenly distributed on the nanosheets.

[0086] In this example, NiMoO 4 , NiMoO-NH and Ni 0.85 Se / NiMoO x The electron microscope image obtained by testing the catalyst shows that the Ni prepared in this application 0.85 Se / NiMoO x The catalyst has high catalytic activity and stability.

[0087] Example 3

[0088] This example is based on Example 1 and describes in detail the Ni based hydrogen evolution reaction in an alkaline environment. 0.85 Se / NiMoO x The surface chemical state of heterojunction catalysts includes:

[0089] like Fig. 9 As shown, the surface chemical state of the catalyst has a great influence on the HER catalytic effect of the catalyst. XPS was used to study Ni 0.85 Se / NiMoO x Catalyst element composition and chemical state. The peaks of Ni, Mo, O and Se in the full spectrum scan ( Fig. 9 a) consistent with the EDS results;

[0090] right Fig. 9 The XPS fine spectrum of Ni in b was fitted by peak splitting, and the peaks at 855.85 and 873.65 eV were attributed to Ni2p 3 / 2 and Ni2p 1 / 2 , the peaks at 861.12 and 879.14 eV are attributed to the satellite peaks of Ni. Fig. 9 The fine spectrum of Mo in c shows that the two peaks with binding energies of 232.14 and 235.21 eV are attributed to Mo. 6+ The two peaks at 228.79 and 232.14 eV are attributed to Mo 4+The peak is attributed to the formation of some Mo 6+ Reduction from high valence state to low valence state. Fig. 9 The fine spectrum of Se in d shows two peaks with binding energies of 55.09 and 55.89 eV, which are attributed to Se3d 5 / 2 and Se3d 3 / 2 (Se 2- ); the peak at 58.88 eV indicates that the surface selenium is in a high oxidation state (SeO x ), formed due to surface oxidation caused by long-term exposure to air. Fig. 9 The fine spectrum of O in e shows two peaks with binding energies of 530.87 and 532.57 eV, which belong to metallic oxygen and adsorbed oxygen, respectively.

[0091] like Fig.10 As shown, further explanation of Ni 0.85 Se composite NiMoO x The role of NiMoO-NH and Ni 0.85 Se and Ni 0.85 Se / NiMoO x The surface elemental chemical state of the catalyst.

[0092] Fig.10 Ni is shown in a 0.85 Se and Ni 0.85 Se / NiMoO x Se3d fine spectrum of catalyst, compared with Ni 0.85 The Se catalyst has a 59.04 eV (SeO x ), Ni 0.85 Se / NiMoO x Catalyst SeO x The peak (58.88 eV) shifted negatively. Fig.10 b shows the fine spectrum of O1s, NiMoO-NH, Ni 0.85 Se and Ni 0.85 Se / NiMoO x The MO peaks of the catalysts are 530.81, 530.8 and 530.75 eV, respectively. 0.85 Se / NiMoO x The catalyst MO peak position shifted negatively. Fig.10 The detailed spectrum of Mo3d in c shows that compared with the NiMo-NH catalyst (Mo 6+ :232.22 and 235.34 eV), Ni 0.85 Se / NiMoO x Mo in catalyst 6+ Peak position negative shift (Mo 6+:232.12 and 235.21eV), and Mo appears 4+ Peak. At the same time, Fig.10 The detailed spectrum of Ni2p in d shows that compared with NiMo-NH catalyst (Ni2p 3 / 2 , 855.56 and Ni2p 1 / 2 , 873.65eV), Ni 0.85 Se / NiMoO x The corresponding peak position of the catalyst is positively shifted (Ni2p 3 / 2 , 855.85 and Ni2p 1 / 2 , 873.65eV). XPS results show that Ni 0.85 The electrons at the Ni site in Se are transferred to Ni 0.85 Se / NiMoO x Mo Ni 0.85 The introduction of Se regulates the Ni 0.85 Se / NiMoO x The electronic structure of crystalline Ni 0.85 Se and amorphous NiMoO x The heterojunction modulates the electronic structure of the catalyst.

[0093] This example describes in detail the Ni0.85Se / NiMoOx catalyst, whose surface chemical state optimization significantly improves the catalytic performance and stability. XPS analysis shows that the selenized Ni 0.85 A heterostructure is formed between Se and NiMoOx, which not only regulates the electronic structure of the catalyst but also optimizes the adsorption and desorption energies of the reaction intermediates, thereby accelerating the HER kinetics.

[0094] Example 4

[0095] This example is based on Example 1 and describes in detail the Ni based hydrogen evolution reaction in an alkaline environment. 0.85 Se / NiMoO x The catalytic activity of hydrogen evolution of heterojunction catalysts includes:

[0096] like Fig.11 As shown, the HER polarization curve of the catalyst measured in 1M KOH solution at 30°C ( Fig.11 a). At low current density, the HER performance of 20% Pt / C catalyst is the best. 0.85 Se / NiMoO x The catalytic performance of the catalyst is close to that of the Pt / C electrode (Ni 0.85 Se / NiMoO x :39mV@10mA·cm -2 , 153mV@100mA·cm -2; 20% Pt / C: 34mV@10mA·cm -2 , 105mV@100mA·cm -2 ). Ni(OH) 2 、NiMoO 4 , NiMoO-NH and Ni 0.85 Se catalysts require overpotentials of 176, 250, 184, and 96 mV to reach 10 mA cm -2 ( Fig.11 d). When the current increases to 500 mA cm -2 When 0.85 Se / NiMoO x The catalytic activity of the catalyst exceeds that of 20% Pt / C catalyst (Ni 0.85 Se / NiMoO x :245mV@500mA·cm -2 ;20%Pt / C: 328mV@500mA·cm -2 ). Using Zview impedance analysis software, Ni(OH) 2 、NiMoO 4 、NiMoO-NH、Ni 0.85 Se and Ni 0.85 Se / NiMoO x EIS impedance spectrum of the catalyst at -100mV overpotential ( Fig.11 b) The order of semicircle radius is NiMoO 4 <Ni(OH) 2 <NiMoO-NH<Ni 0.85 Se <Ni 0.85 Se / NiMoO x , indicating that 0.85 Se / NiMoO x The catalyst has the smallest charge transfer resistance, indicating that it has the fastest HER kinetics, which is better than single Ni 0.85 Se catalyst. Attributed to Ni 0.85 Se / NiMoO x The heterogeneous structure regulates the electronic structure of the catalyst and accelerates the HER reaction kinetics.

[0097] At the same time, the smaller the Tafel slope, the faster the kinetic process is and the smaller the potential increase is when the same current density is reached. Fig.11 c shows Ni(OH) 2 、NiMoO 4 、NiMoO-NH、Ni 0.85 Se and Ni 0.85 Se / NiMoO xThe Tafel slopes of the catalysts are 138, 150, 130, 98 and 85 mV·dec, respectively. -1 Among them, Ni 0.85 Se / NiMoO x The catalyst has a fast HER kinetics, second only to 20% Pt / C (35mV·dec -1 ).

[0098] like Fig.12 As shown, for Ni 0.85 Se / NiMoO x The reason for the excellent HER activity of the catalyst is that the Ni 0.85 Se catalyst and NiMoO without Se source addition x Catalyst and Ni 0.85 Se / NiMoO x The composite catalyst was subjected to CV test ( Fig.12 a~c).

[0099] Ni 0.85 Se、NiMoO x and Ni 0.85 Se / NiMoO x Catalyst C dl 63.1, 13.9 and 264 mF·cm respectively -2 ( Fig.12 d);Ni 0.85 Se / NiMoO x The catalyst has the largest C dl This indicates that the multi-level structure of nanorods covered by nanosheets with distributed nanoparticles can effectively increase the active sites on the catalyst surface. x The conductivity of the nanorod catalyst is poor, but it is significantly improved after selenization. 0.85 Se / NiMoO x The heterogeneous structure of the catalyst optimizes the adsorption and desorption energy of the reaction intermediates and promotes the HER process.

[0100] like Fig.13 As shown, for Ni 0.85 Se / NiMoO x The catalyst showed good HER catalytic performance in 1M KOH solution at 30°C, and the stability of the HER catalytic activity of the catalyst over a long period of time was further investigated. Fig.13 , Ni was tested by constant current method 0.85 Se / NiMoO x HER stability of the catalyst at a current density of 100 mA cm -2 When 0.85 Se / NiMoOx The catalyst can maintain stable catalytic activity for up to 150 h, indicating that the catalyst has good stability. 0.85 Se / NiMoO x The catalyst has good HER catalytic performance and high stability.

[0101] This example describes Ni 0.85 Se / NiMoO x The catalytic activity of the catalyst for hydrogen evolution can be known through the above test. 0.85 Se / NiMoO x The catalyst regulates the electronic structure of the catalyst surface interface, optimizes the adsorption and desorption of reaction intermediates, and accelerates the HER kinetics.

[0102] The above are only preferred embodiments of the present invention, which do not limit the scope of protection of the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any changes, modifications, replacements, integrations and parameter changes to these embodiments within the spirit and principles of the present invention through conventional substitutions or without departing from the principles and spirit of the present invention fall within the scope of protection of the present invention.

Claims

1. Ni based on hydrogen evolution reaction in alkaline environment 0.85 Se / NiMoO x A method for preparing a heterojunction catalyst, characterized in that: include: S1, production of NiMoO4 nanorods by hydrothermal reaction on nickel foam substrate; S2, introducing nickel-molybdenum metal oxides to form NiMoO-NH by loading Ni(OH)2 nanosheets on NiMoO4 nanorods; S3, synthesis of Ni by selenization reduction and ion exchange 0.85 Se / NiMoO x Heterojunction catalysts.

2. The Ni based hydrogen evolution reaction in an alkaline environment according to claim 1 0.85 Se / NiMoO x A method for preparing a heterojunction catalyst, characterized in that: In S1, the nickel foam substrate is pretreated; the pretreatment includes removing the surface oxide and oil stains of the nickel foam substrate, specifically including: immersing the nickel foam in acetone, 3M HCl, water, and ethanol for ultrasonic cleaning for 12-15 minutes, and placing the pretreated nickel foam in anhydrous ethanol for standby use.

3. The Ni based hydrogen evolution reaction in an alkaline environment according to claim 1 0.85 Se / NiMoO x A method for preparing a heterojunction catalyst, characterized in that: The synthesis of NiMoO4 nanorods in S2 specifically comprises the following steps: S2.1.

1. Take a 50mL clean beaker, add 36-40mL H2O into the beaker, and then weigh 0.4-0.5g Ni(NO3)2·6H2O and 0.4-0.5g (NH4)6Mo7O on a balance. 24 4H2O and 0.1-0.2gNH4F; S2.1.2, add to the beaker in order and stir until the solution becomes clear and transparent; S2.1.

3. Transfer the solution to a 50 mL reactor liner and place the pretreated nickel foam in the sealed reactor in a hot air oven for reaction; S2.1.

4. After the reaction is completed, it is naturally cooled to room temperature, washed with ethanol and water for multiple times, and dried in an electric heated forced air oven at 60-65°C to obtain NiMoO4 nanorods.

4. The Ni based hydrogen evolution reaction in an alkaline environment according to claim 3 0.85 Se / NiMoO x A method for preparing a heterojunction catalyst, characterized in that: The nickel nitrate concentration of Ni(NO3)2·6H2O weighed on a balance in S2.1.1 is 0.04-0.05 mol / L; the (NH4)6Mo7O weighed on a balance 24 The concentration of ammonium molybdate in 4H2O is 0.01-0.02 mol / L; the concentration of ammonium fluoride in NH4F weighed by a balance is 0.1-0.15 mol / L.

5. The Ni based hydrogen evolution reaction in alkaline environment according to claim 3 0.85 Se / NiMoO x A method for preparing a heterojunction catalyst, characterized in that: The sealed reactor in S2.1.3 is placed in a hot air oven for reaction at 5-8°C min -1 The temperature was raised at a rate of 160-165°C and the hydrothermal reaction was carried out for 6-6.5 hours.

6. The Ni based hydrogen evolution reaction in an alkaline environment according to claim 1 0.85 Se / NiMoO x A method for preparing a heterojunction catalyst, characterized in that: The synthesis of NiMoO-NH in S2 specifically comprises the following steps: S2.2.1, using precursor NiMoO4 nanorods as a substrate, introducing Ni(OH)2 nanosheets to form a wrinkled structure of NiMoO-NH nanocoated nanorods; S2.2.

2. Take a precursor NiMoO4 nanorod and immerse it in 36-38 mL of a solution containing 40-42 mM nickel nitrate, 160-165 mM urea and 240-245 mM ammonium fluoride; S2.2.3, transfer to the Teflon liner of a 50 mL high-pressure reactor, place the sealed reactor in an electric blast oven, perform hydrothermal reaction at 160-165°C for 6-6.5 hours, and then naturally cool to room temperature; S2.2.

4. Wash with ethanol and water several times, and dry the obtained NiMoO-NH in an electric heated forced air oven at 60-65°C overnight.

7. The Ni based hydrogen evolution reaction in an alkaline environment according to claim 1 0.85 Se / NiMoO x A method for preparing a heterojunction catalyst, characterized in that: The S3 Ni 0.85 Se / NiMoO x The synthesis comprises the following steps: S3.

1. Take the hydrothermal product NiMoO-NH, weigh 0.15-0.18 g of Se powder, pour it into a beaker filled with 36-38 mL of ultrapure water and stir evenly; S3.2, weigh 0.3-0.35g NaBH4 powder, pour it into a beaker and stir until the selenium powder is completely dissolved, then transfer it to the lining of a 50-55mL reactor; S3.3, immerse NiMoO-NH in the solution and seal the reactor, place the sealed reactor in an electric blast oven, perform hydrothermal reaction at 160-165°C for 6-6.5 hours and then naturally cool to room temperature; S3.4, wash with ethanol and water several times, and finally dry in an electric hot air oven at 60-65℃ overnight, and cool naturally to obtain black Ni 0.85 Se / NiMoO x catalyst.

8. The Ni based hydrogen evolution reaction in an alkaline environment according to claim 7 0.85 Se / NiMoO x A method for preparing a heterojunction catalyst, characterized in that: 0.15-0.18 g of Se powder is weighed in S3.1, poured into a beaker filled with 36-38 mL of ultrapure water and stirred evenly. The Se powder is 2-2.2 mmol.

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