CA3132174C

CA3132174C - Z-scheme heterostructure photocatalyst,preparation method, and application thereof

Info

Publication number: CA3132174C
Application number: CA3132174A
Authority: CA
Inventors: Xudong Zhang; Shiwei Lin; Hande CHEN; Jian Fu; Yilong ZHOU; Bao CHEN; Zhengxi LIN; Lingzhuan WANG; Huiyuan LIN; Zhihao FU; Xiucai HUANG
Original assignee: Hainan Unican Science And Technology Innovation Institute Co Ltd
Current assignee: Hainan Unican Science And Technology Innovation Institute Co Ltd
Priority date: 2021-03-25
Filing date: 2021-05-12
Publication date: 2024-04-16
Anticipated expiration: 2041-05-12
Also published as: CA3132174A1

Abstract

The present disclosure provides a 1T/2H-MoSe2@TiO2 nanocomposite, comprising a TiO2 nanorod and a MoSe2 nanoparticle compounded on the TiO2 nanorod; wherein the MoSe2 nanoparticle includes a mixed-phase MoSe2 nanoparticle, and the mixed-phase contains a 1T metal phase and a 2H semiconductor phase. The composite material provided by the present disclosure is an all-solid-state Z-scheme composite system photocatalyst, in which a small part of 2H-MoSe2 is converted into 1T-MoSe2, and the synthesis of 1T phase acts as an electron transferring bridge, which further promotes the separation of electron-hole pairs. Hence, the constructed photoelectrocatalysis system can greatly improve the photoelectrocatalytic performance, thereby increasing the yield of H202, which is more conducive to the production of H202. In addition, the preparation method provided by the present disclosure is simple, and has mild conditions and controllable processes, which is conducive to industrialization and has broad practical prospects.

Description

Z-SCHEME HETEROSTRUCTURE PHOTOCATALYST, PREPARATION METHOD, AND APPLICATION THEREOF
[0001]
FIELD

[0002] The present disclosure belongs to the technical field of photoelectrocatalytic synthesis of H202. It relates to a 1T/2H-MoSe2@Ti02 nanocomposite, method for preparing the same, and application thereof, and specifically to an in-situ synthesized all-solid-state Z-scheme hetero structure photocatalyst, method for preparing the same, and application in photoelectrocatalytic production of H202 thereof.
BACKGROUND

[0003] Currently, methods for industrial synthesis of hydrogen peroxide (H202) mainly include the anthraquinone process and the direct synthesis from hydrogen gas (H2) and oxygen gas (02).
However, the anthraquinone process involves various hydrogenation and oxidation reactions that will consume a large amount of organic solvents and energy; and the direct synthesis from hydrogen gas (H2) and oxygen gas (02) is prone to explosion. Therefore, there is always a need to find a safe, enco-friendly, and energy-saving method for effectively synthesizing H202 in this field. In recent years, many researchers have proposed a lot of feasible methods of producing H202. Photocatalysis technology has become one of the most promising methods for producing H202 owing to its advantages of safety, enco-friendly and energy-saving. It produces H202 on semiconductor materials mainly using water (H20) and 02 as raw materials, as the electrons generated from a semiconductor material under light irradiation are able to reduce 02 into H202.
This process may be divided into continuous two steps of single-step electron oxygen reduction, as shown in reaction equations (1) and (2), or a direct two-electron reduction of 02, as shown in - -Date Recue/Date Received 2022-11-03 direct two-electron reduction of 02, as shown in reaction equation (3).
02 e- ¨> .02 (-0.33 V vs. NHE) (1) = 02-+ 2H+ + e- ¨> H202 (2) 02 + 2H+ + 2e ¨> H202 (0.68 V vs .NHE) (3)

[0004] Moreover, photoelectrochemistry (PEC) also can be used as an effective method for producing H202 by reduction of 02. In a PEC system, a semiconductor material can generate electron-hole pairs under light excitation, and then conduction band electrons can transfer the electrons to the counter electrode to reduce 02 and generate H202 by applying a bias voltage, and hence the electron-hole pairs can be more effectively separated.

[0005] So far, many alternative photocatalysts for reduction 02 to H202, e.g., graphite C3N4, CdS/graphene, W03 and titanium dioxide (Ti02), have been proposed. Among these semiconductor catalysts, Ti02-based photocatalysts have been extensively studied due to their low toxicity, high conduction band gap and high chemical stability. However, the preparation of H202 by TiO2 photocatalysis has a low yield, which is mainly attributed to the following three reasons: 1) due to inherent wide band gap (about 3.2 eV), absorption spectra are limited within the ultraviolet (UV) region; 2) photogenerated electrons and holes have low separation ability, and the electrons and holes are prone to recombine in the system; and 3) peroxide (Ti-00H) is generated under light irradiation, which decomposes H202 adsorbed on the surface of Ti02.

[0006] Therefore, how to find a more suitable method to overcome these above serious shortcomings and improve the performance of TiO2 is widely concerned by these skilled in the art.
SUMMARY

[0007] In view of that, the technical problem to be solved by the present disclosure is to provide a 1T/2H-MoSe2@Ti02 nanocomposite, method for preparing the same, and application thereof, and in particular an in-situ synthesized all-solid-state Z-scheme heterostructure photocatalyst. The 1T/2H-MoSe2@TiO2 nanocomposite prepared according to the present disclosure is a system of heterogeneous combination of semiconductor TiO2 and Date Recue/Date Received 2021-09-24 MoSe2, which contains a 2H semiconductor phase and a 1T metal phase. It is an all-solid-state Z-scheme photocatalyst, and is capable of improving the photoelectrocatalytic performance of photocatalysts and increasing the yield of H202. Also, it can be prepared using a simple method with mild conditions and controllable processes, which is conducive to industrialization and has broad practical prospects.
100081 The present disclosure provides a 1T/2H-MoSe2@TiO2 nanocomposite comprising a TiO2 nanorod and a MoSe2 nanoparticle compounded on the TiO2 nanorod; wherein [0009] the MoSe2 nanoparticle includes a mixed-phase MoSe2 nanoparticle, and the mixed-phase contains a 1T metal phase and a 2H semiconductor phase.
[0010] Preferably, the TiO2 nanorod has a length of 1.8-2 pm.
[0011] The TiO2 nanorod has a diameter of 150-250 nm.
[0012] The 1T/2H-MoSe2@TiO2 nanocomposite includes a 1T/2H-MoSe2@TiO2 nanocomposite for photoelectrocatalysis.
[0013] The photoelectrocatalysis includes photoelectrocatalytic synthesis of H202.
[0014] Preferably, the MoSe2 nanoparticle has a particle size of 15-25 nm.
[0015] The compounding includes coating.
[0016] The TiO2 includes rutile TiO2.
[0017] The 1T/2H-MoSe2@TiO2 nanocomposite is an all-solid-state Z-scheme heterostructure photocatalyst.
[0018] The 1T/2H-MoSe2@TiO2 nanocomposite is prepared by performing hydrothermal process and element-doping on raw materials.
[0019] The present disclosure provides a method for preparing 1T/2H-MoSe2@TiO2 nanocomposite comprising the following steps:
[0020] 1) placing a conductive substrate in a TiO2 precursor solution to perform a hydrothermal reaction, and then performing an annealing treatment, to obtain a TiO2 nanorod;
[0021] 2) mixing a selenium powder solution with a molybdate solution to obtain a Date Recue/Date Received 2021-09-24 precursor solution, and placing the TiO2 nanorod obtained in step 1) in the precursor solution to perform a second hydrothermal reaction, and then performing a second annealing treatment, to obtain an intermediate product 2H-MoSe2@Ti 02; and [0022] 3) under an atmosphere containing ammonia, performing a third annealing treatment on the intermediate product obtained in step 2), to obtain a 1T/2H-MoSe2@TiO2 nanocomposite.
[0023] Preferably, a manner of placing the conductive substrate includes placing the conductive substrate with a conductive surface thereof facing downwards and leaning against an inner wall of a reaction vessel;
[0024] the TiO2 precursor solution contains a titanium source, acid and water;
[0025] the titanium source includes tetrabutyl titanate;
[0026] the acid includes hydrochloric acid; and [0027] the titanium source, the acid and water are present in a volume ratio of 0.4: (5-15):
(5-15).
[0028] Preferably, the hydrothermal reaction is performed at a temperature of 150-180 C;
[0029] the hydrothermal reaction is performed for a duration of 15-24 hours;
[0030] the annealing treatment includes annealing treatment under an air atmosphere;
[0031] the annealing treatment is performed for a duration of 2-3 hours; and [0032] the annealing treatment is performed at a temperature of 400-500 C.
[0033] Preferably, the selenium powder solution includes a solution of selenium powder in hydrazine hydrate, in which the selenium powder and hydrazine hydrate are present in a ratio of mass to volume of (0.025-0.034) g: 1 mL;
[0034] the molybdate solution includes an aqueous solution of sodium molybdate dihydrate in which the sodium molybdate dihydrate and water are present in a ratio of mass to volume of (0.009-0.012) g: 1 mL; and [0035] the selenium powder and molybdate are present in a mass ratio of (0.65-0.7): 1.

Date Recue/Date Received 2021-09-24 [0036] Preferably, the second hydrothermal reaction is performed at a temperature of 170-190 C;
[0037] the second hydrothermal reaction is performed for a duration of 0.5-2 hours;
[0038] the second annealing treatment is performed for a duration of 2-3 hours;
[0039] the second annealing treatment is performed at a temperature of 400-450 C;
[0040] the second annealing treatment includes annealing treatment under an argon gas atmosphere;
[0041] the TiO2 nanorod has an array structure.
[0042] Preferably, the third annealing treatment is performed for a duration of 0.5-2 hours;
[0043] the third annealing treatment is performed at a temperature of 400-450 C;
[0044] the third annealing treatment is performed at a heating rate of 5-10 C/min;
[0045] the atmosphere containing ammonia has a flow rate of 50-150 mL/min; and [0046] the 1T/2H-MoSe2@TiO2 nanocomposite has an array structure.
[0047] The present disclosure further provides use of the 1T/2H-MoSe2@TiO2 nanocomposite according to any one of the above technical solutions or the 1T/2H-MoSe2@TiO2 nanocomposite prepared by using the method according to any one of the above technical solutions in a photocatalyst field.
[0048] The present disclosure provides a 1T/2H-MoSe2@TiO2 nanocomposite comprising a TiO2 nanorod and a MoSe2 nanoparticle compounded on the TiO2 nanorod; wherein the MoSe2 nanoparticle includes a mixed-phase MoSe2 nanoparticle containing a 1T
metal phase and a 2H semiconductor phase. Compared with the prior art, the present disclosure is made based on the following problems in the existing semiconductor catalysts.
Although TiO2 photocatalysts have features such as low toxicity, high conduction band gap and high chemical stability, the preparation of H202 by photocatalysis has a defect of low yield, and the current modification for TiO2 photocatalysts, such as construction of heterojunction, modification with noble metals and element doping, still has problems that are not conducive to the preparation of H202. The research of the present disclosure found that the currently Date Recue/Date Received 2021-09-24 dominant method for improving the photocatalytic performance of TiO2 is to construct type II
heteroj unction, but this kind of heterostructure does not conducive to formation of active free radicals, and hence is not conducive to the preparation of H202 (hydrogen peroxide).
100491 1T/2H-MoSe2@TiO2 nanocomposite is creatively prepared according to the present disclosure. This composite material has a specific morphology, structure and Z-scheme heterostructure, and is a system of heterogeneous combination of semiconductor TiO2 and MoSe2 obtained by heterogeneous combining semiconductor TiO2 and 2H-MoSe2. The nanocomposite provided by the present disclosure is an all-solid-state Z-scheme composite material containing a 2H semiconductor phase and a 1T metal phase. The composite material provided by the present disclosure is a photocatalyst, in which a small part of 2H-MoSe2 is converted into 1T-MoSe2, and the synthesis of 1T phase acts as an electron transferring bridge, which further promotes the separation of electron-hole pairs. Hence, the constructed photoelectrocatalysis system can greatly improve the photoelectrocatalytic performance, thereby increasing the yield of H202, which is more conducive to the production of H202. In addition, the preparation method provided by the present disclosure is simple, and has mild conditions and controllable processes, which is conducive to industrialization and has broad practical prospects.
100501 The 1T/2H-MoSe2@TiO2 nanocomposite provided by the present disclosure is an all-solid-state Z-scheme composite system photocatalyst. The all-solid-state Z-scheme system photocatalyst is prepared by coupling 2H-MoSe2 and TiO2, and further introducing the 1T
metal phase MoSe2 by using in-situ generation method, which is used for photoelectrocatalytic preparation of H202.
100511 The experimental results shows that the 1T/2H-MoSe2@TiO2 nanocomposite prepared according to the present disclosure, as an in-situ synthesized all-solid-state Z-scheme heterostructure photocatalyst, has a better photoelectrocatalytic performance of producing H202.
BRIEF DESCRIPTION OF DRAWINGS
[0052] FIG. 1 is a schematic diagram showing the preparation process of 1T/2H-MoSe2@TiO2 according to the present disclosure;

Date Recue/Date Received 2021-09-24 [0053] FIG. 2 is a scanning electron micrograph of TiO2, 2H-MoSe2@TiO2 and 1T/2H-MoSe2@TiO2 prepared according to the present disclosure;
[0054] FIG. 3 is TEM, HRTEM, and element mapping images of the 1T metal phase and the 2H semiconductor phase, which coexist in MoSe2 nanoparticles and are successfully modified on TiO2, prepared in examples of the present disclosure;
[0055] FIG. 4 is a graph showing transient photocurrent curves of 2H-MoSe2@TiO2 prepared at different hydrothermal reaction time in examples of the present disclosure;
[0056] FIG. 5 is a bar graph showing concentrations of the H202 produced by using 2H-MoSe2@TiO2 prepared at different hydrothermal reaction time in examples of the present disclosure;
[0057] FIG. 6 is a graph showing the comparison of H202 yields using the catalyst 1T/2H-MoSe2@TiO2 prepared in Example 1 of the present disclosure, and using other catalysts or without catalysts;
[0058] FIG. 7 is a graph showing the comparison of ability of photoelectric catalytic degradation of H202 by the catalyst 1T/2H-MoSe2@TiO2 prepared in Example 1 of the present disclosure, and other catalysts or without catalysts; and [0059] FIG. 8 is a graph showing cycle stability test on the H202 prepared by using 1T/2H-MoSe2@TiO2 prepared in Example 1 of the present disclosure.
DETAILED DESCRIPTION
[0060] For further understanding of the present disclosure, preferred embodiments of the present disclosure will be described below in conjunction with examples.
However, it should be understood that these descriptions are only for further illustrating the features and advantages the present invention, rather than limiting the claims of the present invention.
[0061] The source of the raw materials used in the present disclosure is not particularly limited, and the raw materials may be the ones available in market or prepared by using the conventional methods well known to these skilled in the art.
[0062] The purity of the raw materials used in the present disclosure is not particularly limited, and analytically pure or conventional purity in the field of preparation of Date Recue/Date Received 2021-09-24 photocatalysts is preferred in the present disclosure.
[0063] The brand names and abbreviations of the raw materials used in the present disclosure are conventional brand names and abbreviations in the field. Each brand name and abbreviation are clearly and definite in the field of its related use. Those skilled in the art can purchase them from market or prepare them using conventional methods, based on these brand names, abbreviations or their related applications.
[0064] The abbreviations of the processes in the present disclosure are conventional abbreviations in the field. Each abbreviation is clearly and definite in the field of its related use. Those skilled in the art can understand their conventional procedures based on these abbreviations.
[0065] The present disclosure provides a 1T/2H-MoSe2@TiO2 nanocomposite comprising a TiO2 nanorod and a MoSe2 nanoparticle compounded on the TiO2 nanorod; wherein [0066] the MoSe2 nanoparticle include a mixed-phase MoSe2 nanoparticle;
[0067] the mixed-phase contains a 1T metal phase and a 2H semiconductor phase.
[0068] The 1T/2H-MoSe2@TiO2 nanocomposite according to the present disclosure comprises a TiO2 nanorod.
[0069] In the present disclosure, the TiO2 nanorod preferably has a length of 1.8-2 gm, more preferably 1.82-1.98 gm, further more preferably 1.85-1.95 gm, and even more preferably 1.87-1.93 gm.
[0070] In the present disclosure, the TiO2 nanorod preferably has a diameter of 150-250 nm, more preferably170-230 nm, and further more preferably 190-210 nm.
[0071] The 1T/2H-MoSe2@TiO2 nanocomposite according to the present disclosure further comprises a MoSe2 nanoparticle compounded on the TiO2 nanorod. In the present disclosure, the MoSe2 nanoparticle includes a mixed-phase MoSe2 nanoparticle. The MoSe2 nanoparticle is a mixed phase, and the mixed phase contains a 1T metal phase and a 2H
semiconductor phase.
[0072] In the present disclosure, the MoSe2 nanoparticle preferably has a particle size of 15-25 nm, further more preferably 17-23 nm, and even more preferably 19-21 nm.

- 8 -Date Recue/Date Received 2021-09-24 [0073] In the present disclosure, the compounding specifically is coating.
[0074] In the present disclosure, the TiO2 preferably includes rutile TiO2.
[0075] In the present disclosure, the TiO2 nanorod has an array structure.
Further, the 1T/2H-MoSe2@TiO2 nanocomposite also has an array structure.
.. [0076] In the present disclosure, the 1T/2H-MoSe2@TiO2 nanocomposite preferably includes a 1T/2H-MoSe2@TiO2 nanocomposite for photoelectrocatalysis.
Specifically, the 1T/2H-MoSe2@TiO2 nanocomposite is preferably an all-solid-state Z-scheme heterostructure photocatalyst. More specifically, the photoelectrocatalysis preferably includes photoelectrocatalytic synthesis of H202.
[0077] In the present disclosure, the 1T/2H-MoSe2@TiO2 nanocomposite is prepared by performing hydrothermal process and element-doping on raw materials.
[0078] The present disclosure provides a method for preparing 1T/2H-MoSe2@TiO2 nanocomposite, comprising the following steps:
[0079] 1) placing a conductive substrate in a TiO2 precursor solution to perform a hydrothermal reaction, and then performing an annealing treatment, to obtain a TiO2 nanorod;
[0080] 2) mixing a selenium powder solution with a molybdate solution to obtain a precursor solution, placing the TiO2 nanorod obtained in step 1) in the precursor solution to perform a second hydrothermal reaction, and then performing a second annealing treatment, to obtain an intermediate product 2H-MoSe2@Ti02; and [0081] 3) under an atmosphere containing ammonia, performing a third annealing treatment on the intermediate product obtained in step 2), to obtain a 1T/2H-MoSe2@TiO2 nanocomposite.
[0082] In the present disclosure, a conductive substrate is first placed in a TiO2 precursor solution to perform a hydrothermal reaction, and then an annealing treatment is preformed, to .. obtain a TiO2 nanorod.
[0083] In the present disclosure, the conductive substrate preferably includes conductive glasses (FTO).

- 9 -Date Recue/Date Received 2021-09-24 [0084] In the present disclosure, a manner of placing the conductive substrate preferably includes placing the conductive substrate with its conductive surface facing downwards and leaning against an inner wall of a reaction vessel.
[0085] In the present disclosure, the TiO2 precursor solution preferably contains a titanium source, acid, and water, wherein the titanium source includes tetrabutyl titanate, and the acid includes hydrochloric acid.
[0086] In the present disclosure, the titanium source and the acid preferably has a volume ratio of 0.4: (5-15), more preferably 0.4: (7-13), and even more preferably 0.4: (9-11).
[0087] In the present disclosure, the titanium source and water preferably has a volume ratio of 0.4: (5-15), more preferably 0.4: (7-13), and even more preferably 0.4: (9-11).
[0088] In the present disclosure, the hydrothermal reaction are preferably performed at a temperature of 150-180 C, more preferably 155-175 C, and even more preferably 160-170 C.
[0089] In the present disclosure, the hydrothermal reaction are preferably performed for a duration of 15-24 hours, more preferably 17-22 hours, and even more preferably 19-20 hours.
[0090] In the present disclosure, the annealing treatment preferably includes annealing treatment under an air atmosphere.
[0091] In the present disclosure, the annealing treatment is preferably performed for a duration of 2-3 hours, more preferably 2.2-2.8 hours, and even more preferably 2.4-2.6 hours.
[0092] In the present disclosure, the annealing treatment is preferably performed at a temperature of 400-500 C, more preferably 420-480 C, and even more preferably 440-460 C.
[0093] In the present disclosure, subsequently, a selenium powder solution is mixed with a molybdate solution to obtain a precursor solution, and the TiO2 nanorod obtained in step 1) is palced in the precursor solution to perform a second hydrothermal reaction, and then a second annealing treatment is performed, to obtain an intermediate product 2H-MoSe2@Ti02.
[0094] In the present disclosure, the selenium powder solution preferably includes a solution of selenium powder in hydrazine hydrate.
[0095] In the present disclosure, the selenium powder and hydrazine hydrate are preferably

- 10 -Date Recue/Date Received 2021-09-24 present in a ratio of mass to volume of (0.025-0.034) g: 1 mL, more preferably (0.027-0.032) g: 1 mL, and even more preferably (0.029-0.030) g: 1 mL.
[0096] In the present disclosure, the molybdate solution preferably includes an aqueous solution of sodium molybdate dihydrate.
[0097] In the present disclosure, the sodium molybdate dihydrate and water are preferably present in a ratio of mass to volume of (0.009-0.012) g: 1 mL, more preferably (0.009-0.011) g: 1 mL, and even more preferably (0.01-0.012) g: 1 mL.
[0098] In the present disclosure, the selenium powder and molybdate are preferably in a mass ratio of (0.65-0.7): 1, more preferably (0.66-0.69): 1, and even more preferably (0.67-0.68): 1.
[0099] In the present disclosure, the second hydrothermal reaction are preferably performed at a temperature of 170-190 C, more preferably 172-188 C, further more preferably 175-185 C, and even more preferably 177-183 C.
[0100] In the present disclosure, the second hydrothermal reaction are preferably performed for a duration of 0.5-2 hours, more preferably 0.7-1.8 hours, and even more preferably 1.0-1.5 hours.
[0101] In the present disclosure, the second annealing treatment is preferably performed for a duration of 2-3 hours, more preferably 2.2-2.8 hours, and even more preferably 2.4-2.6 hours.
[0102] In the present disclosure, the second annealing treatment is preferably performed at a temperature of 400-450 C, more preferably 410-440 C, and even more preferably 420-430 C.
[0103] In the present disclosure, the annealing treatment preferably includes annealing treatment under an argon gas atmosphere.
[0104] At last, in the present disclosure, under an atmosphere containing ammonia, a third annealing treatment is performed on the intermediate product obtained in step 2) to obtain a 1T/2H-MoSe2@TiO2 nanocomposite.
[0105] In the present disclosure, the third annealing treatment is preferably performed for a duration of 0.5-2 hours, more preferably 0.7-1.8 hours, and even more preferably 1.0-1.5

- 11 -Date Recue/Date Received 2021-09-24 hours.
[0106] In the present disclosure, the third annealing treatment is preferably performed at a temperature of 400-450 C, more preferably 410-440 C, and even more preferably 420-430 C.
[0107] In the present disclosure, the third annealing treatment is preferably performed at a heating rate of 5-10 C/min, more preferably 6-9 C/min, and even more preferably 7-8 C/min.
[0108] In the present disclosure, the atmosphere containing ammonia preferably has a flow rate of 50-150 mL/min, more preferably 70-130 mL/min, and even more preferably mL/min.
[0109] In the present disclosure, in order to provide a better complete and detailed technical solution, well ensure the structure and morphology of the 1T/2H-MoSe2@TiO2 nanocomposite, and improve the photocatalytic performance of the 1T/2H-MoSe2@TiO2 nanocomposite, the above-mentioned method for preparing the 1T/2H-MoSe2@TiO2 nanocomposite may specifically comprises the following steps:
[0110] (1) Preparation of the TiO2 nanorod material by hydrothermal process:
[0111] preparing a precursor solution by selecting a conductive glass (PTO) as a substrate for growing TiO2 nanorods and using tetrabutyl titanate as a titanium source, transferring the precursor solution into an autoclave with a polytetrafluoroethylene liner, and performing reaction for 15-24 hours; and at last, nnealing the sample inside a muffle furnace under an air atmosphere to obtain rutile TiO2. Specifically, the reaction may be performed at a temperature of 150 C; and the annealing may be performed at a temperature of 450 C.
[0112] (2) Preparation of the 2H-MoSe2@TiO2 material by hydrothermal process [0113] mixing a selenium powder solution and a sodium molybdate dihydrate solution, and stirring to obtain a precursor solution; transferring the precursor solution into an autoclave with a polytetrafluoroethylene liner; immersing the TiO2 material prepared in step (1) into the precursor solution inside the polytetrafluoroethylene line, and performing reaction for 0.5-2 hours; and at last, annealing the sample inside a tube furnace under an argon gas atmosphere to obtain a highly crystalline 2H-MoSe2@Ti02. Specifically, the stiffing may be performed for a duration of 30 min; the reaction may be performed at a temperature of 180 C; and the

- 12 -Date Recue/Date Received 2021-09-24 annealing may be performed at a temperature of 450 C.
[0114] (3) Preparation of the 1T/2H-MoSe2@TiO2 material by N-doping [0115] annealing the prepared 2H-MoSe2@TiO2 sample inside a tube furnace, under an NH3 gas atmosphere for 0.5-2 hours, to obtain a T/2H-MoSe2@TiO2 material.
Specifically, the annealing may be performed at a temperature of 400 C.
[0116] In the step (1), the precursor in the Ti source precursor solution is formulated from tetrabutyl titanate, hydrochloric acid and water, and the volume ratio of them can be controlled at 0.4: 10: 10.
[0117] In the step (2), the selenium powder solution may be specifically formulated from 0.158 g of selenium powder and 5 mL of hydrazine hydrate; and the sodium molybdate dihydrate solution may be specifically formulated from 0.242 g of ammonium molybdate dihydrate and 25 mL of deionized water.
[0118] In the step (3), in the annealing conditions, the heating rate can be specifically 10 C/min, and the NH3 flow rate can be specifically 100 mL/min.
[0119] Preferably, in the preparation of TiO2 nanorod array photocatalyst by hydrothermal process, tetrabutyl titanate is selected as the Ti source to prepare the precursor solution; and then the precursor solution is transferred into the autoclave with a polytetrafluoroethylene liner, to perform reaction at 150 C for 15-24 h.
[0120] Preferably, in the preparation of 2H-MoSe2@TiO2 photocatalyst by hydrothermal process, the TiO2 photocatalyst prepared in the above step is immersed in a mixed solution of the Se powder and sodium molybdate dihydrate, and subjected to hydrothermal treatment after being stand for 1 hour; and at last, the annealing is performed at high temperature under an argon gas atmosphere.
[0121] Preferably, in the preparation of the 1T/2H-MoSe2@TiO2 photocatalyst by N-doping, the 2H-MoSe2@TiO2 photocatalyst prepared in the above step is annealed inside a tube furnace under an NH3 gas atmosphere for 1 hour.
[0122] Reference is made to FIG. 1, which is a schematic diagram showing the preparation process of 1T/2H-MoSe2@TiO2 according to the present disclosure.

- 13 -Date Recue/Date Received 2021-09-24 [0123] The 1T/2H-MoSe2@TiO2 nanocomposite provided by the present disclosure is an all-solid-state Z-scheme heterojunction photocatalyst which is a system of heterogeneous combination of semiconductor TiO2 and 1T/2H-MoSe2, in which the 1T metal phase MoSe2 is in-situ introduced between TiO2 and 2H-MoSe2 in a way of N-doping. The N-doping uses NH3 as N source, and annealing time is preferably 0.5-2 h.
[0124] The research of the present disclosure found that although TiO2-based catalysts has the advantages of low toxicity, high conduction band gap and high chemical stability, and also their photoelectrocatalytic performance can be effectively improved by constructing heterojunction, the decreases in potential of the photogenerated holes in valence band (VB) and in potential of electrons in the conduction band are inevitable, which is not conducive to the formation of active free radicals, and thus maintaining the energy band structure of TiO2 plays an important role in the production of hydrogen peroxide. In the present disclosure, firstly the TiO2 nanorod is prepared on FTO through hydrothermal process, and the TiO2 nanorod is subjected to annealing, to obtain rutile TiO2; subsequently MoSe2 is modified on the TiO2 nanorod through hydrothermal process again, to construct and obtain Z-scheme 2H-MoSe2@Ti02; and at last part of the 2H-MoSe2 is converted into 1T-MoSe2 through N-doping method, to construct and obtain the 1T/2H-MoSe2@TiO2 all-solid-state Z-scheme heterostructure photocatalyst. The synthesis of the 1T phase acts as an electron transferring bridge, and further promotes the separation of electron-hole pairs, thereby being more conducive to the production of H202.
[0125] The present disclosure further provides use of the 1T/2H-MoSe2@TiO2 nanocomposite according to any one of the above technical solutions or the 1T/2H-MoSe2@TiO2 nanocomposite prepared by using the method according to any one of the above technical solutions in a photocatalyst [0126] The all-solid-state Z-scheme heterostructure photocatalyst provided by the present disclosure is a system of heterogeneous combination of semiconductor TiO2 and MoSe2. The T/2H-MoSe2@TiO2 all-solid-state Z-scheme photocatalyst is prepared by modifying MoSe2 nanoparticles on the TiO2 nanorod, and subsequently performing annealing under an NH3 gas atmosphere to transform a small part of the 2H semiconductor phase MoSe2 into the IT metal phase MoSe2.

- 14 -Date Recue/Date Received 2021-09-24 [0127] In the above-mentioned steps of the present disclosure, an in-situ synthesized all-solid-state Z-scheme heterostructure photocatalyst and preparation method thereof, and use in photoelectrocatalytic production of H202 thereof are provided. The 1T/2H-MoSe2@TiO2 nanocomposite provided by the present disclosure has a specific morphology, structure and Z-scheme heterostructure, which is a system of heterogeneous combination of semiconductor TiO2 and MoSe2 obtained by heterogeneous combining semiconductor TiO2 and 2H-MoSe2. In the present disclosure, a hydrothermal process and element doping are combined, to prepare the 1T/2H-MoSe2@TiO2 all-solid-state Z-scheme heterojunction photocatalyst. Heterogeneous combining semiconductor TiO2 and 2H-MoSe2, and in-situ transforming a small part of the 2H-MoSe2 into 1T-MoSe2 through doping, which can be used as an electron-transferring bridge to construct a photoelectrocatalytic system, thereby greatly improving photoelectrocatalytic performance of the photocatalyst and increasing the yield of H202.
[0128] The nanocomposite provided by the present disclosure contains a 2H
semiconductor phase and a 1T metal phase, which is a 1T/2H-MoSe2@TiO2 all-solid-state Z-scheme composite material. The composite material is a photocatalyst, in which a small part of 2H-MoSe2 is converted into 1T-MoSe2, and the synthesis of 1T phase acts as an electron transferring bridge, which further promotes the separation of electron-hole pairs. Hence, the constructed photoelectrocatalysis system can greatly improve the photoelectrocatalytic performance, thereby increasing the yield of H202, which is more conducive to the production of H202. In addition, the preparation method provided by the present disclosure is simple, and has mild conditions and controllable processes, which is conducive to industrialization and has broad practical prospects.
[0129] The 1T/2H-MoSe2@TiO2 nanocomposite provided by the present disclosure is an all-solid-state Z-scheme composite system photocatalyst. The all-solid-state Z-scheme system photocatalyst is prepared by coupling 2H-MoSe2 and TiO2, and further introducing the 1T
metal phase MoSe2 by using in-situ generation method, which is used for photoelectrocatalytic preparation of H202.
[0130] The experimental results shows that the 1T/2H-MoSe2@TiO2 nanocomposite prepared according to the present disclosure, as an in-situ synthesized all-solid-state Z-scheme

- 15 -Date Recue/Date Received 2021-09-24 heterostructure photocatalyst, has a better photoelectrocatalytic performance of producing H202.
[0131] In order to further describe the present disclosure, the 1T/2H-MoSe2@TiO2 nanocomposite, preparation method, and use thereof provided by the present disclosure will be described in detail below in conjunction with examples. It should be understood that these examples are implemented under the premise of the technical solution of the present disclosure, and that the detailed implementation modes and specific operating procedures are given, merely for illustrating the features and advantages of the present disclosure, rather than limiting the claims of the invention, and that the scope of protection of the invention is not .. limited to the following examples.
Examples [0132] (1) Preparation of TiO2 material by hydrothermal process [0133] The FTO substrate needed to be washed, and the steps for washing were washing with acetone, ethanol and deionized water in sequence through ultrasonication for 10 min. A
precursor solution of TiO2 was prepared and transferred into an autoclave with a polytetrafluoroethylene liner. Subsequently, the washed FTO was placed to the polytetrafluoroethylene liner, with its conductive surface facing downwards and being leaned against the liner at a predetermined degree. After being tightened, the reaction kettle was placed in a blast drying oven, to perform reaction for 15-24 hours at 150 C.
After natural cooling, the prepared sample was taken out and washed with deionized water and ethanol in sequence. Subsequently, the sample was dried in a vacuum dry box for 12 hours, and at last annealed in a muffle furnace at 450 C at a heating rate of 2 C/min under an air atmosphere to obtain rutile TiO2.
[0134] The precursor solution of TiO2 was formulated from tetrabutyl titanate, hydrochloric acid and water, with their volume ratio controlled at 0.4: 10: 10. After hydrochloric acid and water were well mixed, tetrabutyl titan ate was added and mixed for 5 min before being taken out.
[0135] (2) Preparation of 2H-MoSe2@TiO2 material by hydrothermal process

- 16 -Date Recue/Date Received 2021-09-24 [0136] A sodium molybdate dihydrate solution and a selenium powder solution were mixed, and stirred for 30 min to obtain a MoSe2 precursor solution. The precursor solution was then transferred into an autoclave with a polytetrafluoroethylene liner. The rutile TiO2 material prepared in step (1) was immersed in the precursor solution in the polytetrafluoroethylene liner, with the surface for growing TiO2 facing downwards and being leaned against the liner.
After being tightened, the reaction kettle was placed in a blast drying oven, with heating rate program set to 3 C/min, to perform reaction at a temperature of 180 C and for a duration of 0.5-2 hours. For a duration of 30 min, 60 min, 90 min and 120 min, 4 groups of samples were prepared respectively. After the reaction was completed, the prepared samples were allowed to naturally cool to room temperature before being taken out. The prepared samples were taken out and washed with deionized water and ethanol in sequence.
Subsequently, the samples were dried for 12 hours in a vacuum dry box, and at last annealed in a tube furnace at 450 C under an argon gas atmosphere to obtain a highly crystalline 2H-MoSe2@Ti02.
[0137] The ammonium molybdate aqueous solution was prepared by mixing 0.242 g of ammonium molybdate dihydrate and 25 mL of deionized water with magnetic stirring for 30 min. The selenium powder aqueous solution was prepared by mixing 0.158 g of selenium powder and 5 mL of hydrazine hydrate followed by 5 min of ultrasonication to well mix them.
In addition, in the precursor solution, Mo and Se were present in a molar ratio of 1: 2.
[0138] (3) Preparation of 1T/2H-MoSe2@TiO2 material by N-doping:
[0139] The prepared 2H-MoSe2@TiO2 sample was annealed under an NH3 gas atmosphere at 400 C for 0.5-2 hours in a tube furnace, to obtain a T/2H-MoSe2@TiO2 material.
[0140] The flow rate of NH3 was controlled at 100 mL/min. The heating rate was controlled at 10 C/min. The preferred annealing time for 1T/2H-MoSe2@TiO2 photocatalysis was 1 h.
[0141] The 1T/2H-MoSe2@TiO2 composite material prepared according to the present .. disclosure was characterized.
[0142] Reference is made to FIG. 2, which is a scanning electron micrograph of TiO2, 2H-MoSe2@TiO2 and 1T/2H-MoSe2@TiO2 prepared according to the present disclosure.
[0143] In FIG. 2, (a, d) stands for TiO2, (b, e) stands for 2H-MoSe2@Ti02, and (c, f) stands

- 17 -Date Recue/Date Received 2021-09-24 for 1T/2H-MoSe2@TiO2.
[0144] Reference is made to FIG. 3, which is TEM, HRTEM, and element mapping images of the 1T metal phase and the 2H semiconductor phase, which coexist in MoSe2 nanoparticles and are successfully modified on TiO2, prepared in examples of the present disclosure.
[0145] In FIG. 3, (a) stands for a TEM image; (b, c) stands for HRTEM images;
and (d) stands for mapping images.
[0146] The 1T/2H-MoSe2@TiO2 composite material prepared by Example 1 of the present disclosure was tested on its performance.
[0147] Test on Photoelectrocatalytic Performance of Preparation of H202 [0148] TiO2, the prepared 2H-MoSe2@Ti02, and 1T/2H-MoSe2@TiO2 were used as photoanode materials. Pt sheet and Ag/AgC1 were used as a counter electrode and a reference electrode, respectively. The reaction cell was a quartz cell. The three-electrode system was connected with an ultraviolet lamp source, a peristaltic pump, an oxygen source and an electrochemical workstation, to construct a photoelectrocatalytic test system.
The peristaltic pump can take out the aqueous solution samples at different reaction times, for detection of H202 concentrations. The concentration detection method was iodine reduction method. The method included steps of taking 1 mL of reaction solution, adding 1 mL of KI
(0.1 M) and 50 [IL of ammonium molyb date (0.01 M) solution, well mixing, followed by standing for 15 min until the reaction was completed, and measuring absorbance by ultraviolet-visible .. spectrophotometry. The test result will show an absorption peak at 353nm, and then it was compared with calibration curves to obtain H202 concentrations. The performance test results of MoSe2@TiO2 photocatalysts are shown in FIGs. 4-6.
[0149] Reference is made to FIG. 4, which is a graph showing transient photocurrent curves of 2H-MoSe2@TiO2 prepared at different hydrothermal reaction time in examples of the present disclosure.
[0150] Reference is made to FIG. 5, which is a bar graph showing concentrations of the H202 produced by using 2H-MoSe2@TiO2 prepared at different hydrothermal reaction time in examples of the present disclosure.

- 18 -Date Recue/Date Received 2021-09-24 [0151] In FIG. 5, the 2H-MoSe2@TiO2 sample with a hydrothermal reaction time of 1 hour has the highest H202 yield.
[0152] Reference is made to FIG. 6, which is a graph showing the comparison of yields using the catalyst 1T/2H-MoSe2@TiO2 prepared in Example 1 of the present disclosure, and using other catalysts or without catalysts.
[0153] In FIG. 6, (a) is the curves showing the change of H202 generation concentration over time, under the condition of light illumination or without light illumination; and (b) shows the net H202 yields from different samples after removing that from the blank sample.
[0154] It can be seen from FIG. 6 that the H202 yields from 1T/2H-MoSe2@TiO2 reached to 4.7 times of that from TiO2 catalyst.
[0155] Reference is made to FIG. 7, which is a graph showing the comparison of ability of photoelectric catalytic degradation of H202 by the catalyst 1T/2H-MoSe2@TiO2 prepared in Example 1 of the present disclosure, and other catalysts or without catalystss.
[0156] It can be seen from FIG. 7 that in terms of degradation of H202, the degradation ability of 1T/2H-MoSe2@TiO2 is worse than that of TiO2, demonstrating that 1T/2H-MoSe2@TiO2 has less degradation of H202 generated in real time, which is one reason for the increase in H202 yield.
[0157] Reference is made to FIG. 8, which is a graph showing cycle stability test on the H202 prepared by using 1T/2H-MoSe2@TiO2 prepared in Example 1 of the present disclosure.
[0158] It can be seen from FIG. 8 that 1T/2H-MoSe2@TiO2 (60 min of hydrothermal reaction and 1 hour of annealing) prepared according to the present disclosure exhibits good cycle stability.
[0159] The above provides a detailed introduction to the in-situ synthesized all-solid-state Z-scheme heterostructure photocatalyst provided by the present disclosure and preparation method thereof, as well as use in photoelectrocatalytic production of H202 thereof. To illustrate the principle and implementation of the present disclosure, the specific examples are used herein, their description above is only intended to facilitate understanding of the method

- 19 -Date Recue/Date Received 2021-09-24 and core concept of the present invention, including the best implementation mode, and to enable any one of the skilled in the art to implement the present invention including any device or system in manufacture and use, as well as any combined methods. It should be noted that for those skilled in the art, various improvements and modifications may be made without departing from the principle of the present disclosure, and these improvements and modifications should fall within the scope of protection of the present disclosure. The protection scope of this patent is defined by the claims and can include other embodiments that a person skilled in the art would know. The said other embodiments should also be included in the scope of the claims, if they contain structural elements that are not different .. from the literal expression of claims, or equivalent structural elements that are not substantially different from the literal expression of the claims.

- 20 -Date Recue/Date Received 2021-09-24

Claims

1. A 1T/2H-MoSe2@TiO2 nanocomposite, comprising a TiO2 nanorod and a MoSe2 nanoparticle compounded on the TiO2 nanorod; wherein the 1T/2H-MoSe2@TiO2 nanocomposite is an all-solid-state Z-scheme heterostructure photocatalyst; and the MoSe2 nanoparticle includes a mixed-phase MoSe2 nanoparticle, and the mixed-phase contains a 1T metal phase and a 2H semiconductor phase.

2. The 1T/2H-MoSe2@TiO2 nanocomposite according to claim 1, wherein the TiO2 nanorod has a length of 1.8-2 pm; and the TiO2 nanorod has a diameter of 150-250 nm.

3. The 1T/2H-MoSe2@TiO2 nanocomposite according to claim 1, wherein the MoSe2 nanoparticle has a particle size of 15-25 nm;
the MoSe2nanoparticle is coated on the TiO2 nanorod; and the TiO2 includes rutile TiO2.

4. A method for preparing 1T/2H-MoSe2@TiO2 nanocomposite, comprising the following steps:
1) placing a conductive substrate in a TiO2 precursor solution to perform a first hydrothermal reaction, and then performing a first annealing treatment, to obtain a TiO2 nanorod;
2) mixing a selenium powder solution with a molybdate solution to obtain a precursor solution, and placing the TiO2 nanorod obtained in step 1) in the precursor solution to perform a second hydrothermal reaction, and then performing a second annealing treatment at a temperature of 400-450 C, to obtain an intermediate product 2H-MoSe2@Ti02; and 3) under an atmosphere containing ammonia, performing a third annealing treatment on the intermediate product obtained in step 2), to obtain a 1T/2H-MoSe2@TiO2 nanocomposite having an all-solid-state Z-scheme heterostructure.

5. The method according to claim 4, wherein a manner of placing the conductive substrate includes placing the conductive substrate with a conductive surface thereof facing downwards and leaning against an inner wall of reaction vessel; and the TiO2 precursor solution contains a titanium source, acid and water;
wherein the titanium source includes teuabutyl titanate;
the acid includes hydrochloric acid; and the titanium source, the acid and water are present in a volume ratio of 0.4:
(5-15): (5-15).

6. The method according to claim 4, wherein the first hydrothermal reaction is performed at a temperature of 150-180 C;
the first hydrothermal reaction is performed for a duration of 15-24 hours;
the first annealing treatment includes annealing treatment under an air atmosphere;
the first annealing treatment is performed for a duration of 2-3 hours; and the first annealing treatment is performed at a temperature of 400-500 C.

7. The method according to claim 4, wherein the selenium powder solution includes a solution of selenium powder in hydrazine hydrate, in which the selenium powder and hydrazine hydrate are present in a ratio of mass to volume of (0.025-0.034) g: 1 mL;
the molybdate solution includes an aqueous solution of sodium molybdate dihydrate, in which the sodium molybdate dihydrate and water are present in a ratio of mass to volume of (0.009-0.012) g: 1 mL; and the selenium powder and molybdate are present in a mass ratio of (0.65-0.7):
1.

Date Recue/Date Received 2023-07-07

8. The method according to claim 4, wherein the second hydrothermal reaction is performed at a temperature of 170-190 C;
the second hydrothermal reaction is performed for a duration of 0.5-2 hours;
the second annealing treatment is performed for a duration of 2-3 hours;
the second annealing treatment includes annealing treatment under an argon gas atmosphere;
and the TiO2 nanorod has an array structure.

9. The method according to claim 4, wherein the third annealing treatment is performed for a duration of 0.5-2 hours;
the third annealing treatment is perfouned at a temperature of 400-450 C;
the third annealing treatment is performed at a heating rate of 5-10 C/min;
the atmosphere containing ammonia has a flow rate of 50-150 mL/min; and the 1T/2H-MoSe2@TiO2 nanocomposite has an array structure.

10. Use of the 1T/2H-MoSe2@TiO2 nanocomposite according to any one of claims 1-4 or the 1172H-MoSe2g1i02 nanocomposite prepared by using the method according to any one of claims 5-9 in a photocatalyst field.

11. The use according to claim 10, wherein the 1T/2H-MoSe2@TiO2 nanocomposite is a catalyst for photoelectrocatalytic synthesis of H202.