LU500927B1

LU500927B1 - MoSe2/DEFECT-RICH ZnIn2S4/CdSe DUAL Z-SCHEME PHOTOCATALYST FOR PHOTOCATALYTIC WATER SPLITTING TO HYDROGEN

Info

Publication number: LU500927B1
Application number: LU500927A
Authority: LU
Inventors: Zhenjiang Li; Xianghu Wang; Hui Yang; Alan Meng; Xuehua Wang
Original assignee: Qingdao Univ Of Science And Technology
Priority date: 2021-05-08
Filing date: 2021-11-30
Publication date: 2022-05-30
Also published as: ZA202109086B; CN113171780B; CN113171780A; NL2030019B1

Abstract

The present disclosure discloses a MoSe2/defect-rich ZnIn2S4/CdSe dual Z-scheme photocatalyst with efficient photocatalytic water splitting to hydrogen performance, and belongs to the technical field of photocatalysis. In the present disclosure, the MoSe2/defect-rich ZnIn2S4/CdSe dual Z-scheme photocatalyst with flower-like microsphere structure is prepared by one-step hydrothermal method using the prepared ZnIn2S4, Na2MoO4·2H2O, Cd(CH3COO)2·2H2O and Se powder as raw materials and hydrazine hydrate as the reducing agent. Nanosheet-shaped MoSe2 and granular CdSe are bonded on the surface of defect-rich ZnIn2S4 through Mo-S bond and Cd-S bond, respectively, thus a close heterointerface is formed between the defect-rich ZnIn2S4 and MoSe2, as well as defect-rich ZnIn2S4 and CdSe, which further contributed to a strong built-in electric field.

Description

MoSe2/DEFECT-RICH ZnIn2S4/CdSe DUAL Z-SCHEME PHOTOCATALYST FOR 500927

PHOTOCATALYTIC WATER SPLITTING TO HYDROGEN TECHNICAL FIELD

[01] The present disclosure belongs to the technical field of photocatalysis, and specifically relates to a MoSez/defect-rich ZnIn2S4/CdSe dual Z-scheme photocatalyst with excellent photocatalytic water splitting to hydrogen performance.

BACKGROUND ART

[02] The development of industrial civilization has brought us numerous conveniences, but also caused lots of problems such as energy crisis and environmental pollution. Therefore, finding a sustainable energy conversion and utilization method is an effective means to solve the above problem. Solar-energy-driven hydrogen evolution from photocatalytic water splitting can convert solar energy to hydrogen energy, and the combustion product of the hydrogen energy is still water, which perfectly interpretates the classic process of natural material recycling and sustainable development by causing no energy waste and environmental pollution. However, in order to realize the practical industrial production application of photocatalytic hydrogen evolution from water splitting, a first problem that needs to be solved is the development of high-efficiency photocatalyst.

[03] As a typical ternary metal sulfide semiconductor with layered structure, zinc indium sulfide (ZnlIn,S4) has a direct band gap width of about 2.06-2.85 eV and good visible light response, so that ZnIn2S4 has been widely used as catalyst for photocatalytic water splitting to hydrogen. However, the single ZnIn2S4 photocatalyst usually faces with severe recombination of photogenerated carriers, leading to the low photocatalytic efficiency. Constructing heterojunction by combining ZnIn2S4 with other semiconductor materials with different energy band structure is one of effective ways to improve the photocatalytic water splitting to hydrogen performance. Meng et al. prepared a ZnIn:Sy/g-C3N4 heterojunction photocatalyst by hydrothermal method and applied for photocatalytic water splitting to hydrogen. The optimized photocatalyst performs a hydrogen production rate of 6,095.1 pmol -g!-h! under visible light (\>420 nm), which is 2 times and 6 times than that of the individual ZnIn2S4 and g-C3N4, respectively (Qin Y Y, Li H, Lu J, Feng Y H, Meng F Y, Ma C C, Yan Y S, Meng M J, Applied Catalysis B: Environmental 277 (2020) 119254). Lu et al. obtained a CooSg/ZnIn2S4 heterojunction photocatalyst by growing ZnIn2S4 on the surface of Co9Ss nanotube via solvothermal method, which exhibits a hydrogen production efficiency of 9,039 umol-g*-h"! under visible light irradiation (Zhang G P, Chen D Y, Li N J, Xu Q F, Li H, He J H and Lu J M, Angew. Chem. Int. Ed, DOI: 10.1002/anie. 202000503). Chinese invention patent (application number: 201710278270.2) discloses a 1 low-cost two-dimensional sulfide nanojunction photocatalyst (MoS»/Cu-ZnIn2S4) for hydrogen 200927 production and its preparation method and application. Under visible light irradiation (A>420 nm), the hydrogen production efficiency of the photocatalyst reaches 5,489 umol-g!-h'!, which is 65 times than that of the single Cu-ZnIn2S4 photocatalyst.

[04] With continuous and deep research of photocatalytic reaction mechanism, researchers have found that although the separation efficiency of photogenerated carriers can be improved in the traditional type-I or type-II heterojunction, the redox capacity of photogenerated carriers would be reduced, and as a result, the efficiency of photocatalytic water splitting to hydrogen is limited. In contrast, by constructing Z-scheme heterojunction, not only can the light absorption capacity of photocatalyst and the separation efficiency of the photocarriers be significantly improved, but also photogenerated electrons with high reactivity can be retained, thus achieving higher photocatalytic water splitting to hydrogen performance. In order to construct the Z-scheme heterojunction, semiconductors with matched energy band need to be selected first. The different energy band structures are favorable for forming built-in electric field at the heterointerface, thereby promoting the transfer of photogenerated carriers at the interface following Z-scheme mechanism. In addition, construction of close atomic-level interface bonding between different semiconductors by using suitable preparation process is also a strong guarantee for Z-scheme charge transfer. Zhang et al. prepared a CAS@ZnIn2S4 direct Z-scheme heterojunction photocatalyst connected by chemical bonds via a low-temperature solvothermal method. Mechanism research results show that under light irradiation, the synergistic effect of close heterojunction interface and built-in electric field gave rise to that electrons on the conduction band of ZnIn2S4 transferred to the valence band of CdS to combine with photogenerated holes, so that photogenerated electrons with high reduction capability on the conduction band of CdS and photogenerated holes with high oxidation capability on the valence band of ZnIn:S4 were retained, thereby achieving efficient photocatalytic water splitting to hydrogen and hydrogen peroxide performance (Zhang E H, Zhu Q H, Huang J H, Liu J, Tan G Q, Sun CJ, Li T, Liu S, Li Y M, Wang H Z, Wan X D, Wen Z H, Fan F T, Zhang J T, and Ariga K, Applied Catalysis B: Environmental 293(2021) 120213). According to the basic principle of Z-scheme heterojunction photocatalytic reaction, it can be inferred that when three kinds of semiconductors with suitable band gap structures are closely bonded to form a dual Z-scheme photocatalyst, not only can the separation of the photogenerated carriers be further promoted, but also more photogenerated electrons with high reactivity can be retained, and at the same time, the light absorption range can be expanded, thus realizing more efficient photocatalytic water splitting to hydrogen activity than that of binary Z-scheme heterojunction. Therefore, by comprehensively considering the influence of the energy band structure and interface bonding 2 mode on the transfer of charge at the heterojunction interface, it is expected to realize the precise 200927 control over the dual Z-scheme photocatalyst, so that the photocatalyst with excellent photocatalytic water splitting to hydrogen performance can be obtained. However, there are few reports on related researches.

[05] In the present disclosure, by comprehensively considering a synergistic promotion effect of energy band structure and interface bonding state on Z-scheme charge transfer mechanism, a MoSe»/defect-rich ZnIn,S4/CdSe dual Z-scheme photocatalyst for water splitting to hydrogen is prepared using a simple hydrothermal method. First, energy level structure of MoSez, ZnIn2S4 and CdSe meet the energy level requirements of Z-scheme charge transfer. In addition, the abundant unsaturated sulfur atoms on the surface of defect-rich ZnIn2S4 can provide excellent active sites for the growth of MoSe» and CdSe, and finally lead to the in-situ nucleate and grow of MoSez and CdSe on defect-rich ZnIn2S4 through Mo-S bond and Cd-S bond, respectively. This heterojunction interface connected by chemical bonds can provide fast channels for the transfer of the photogenerated carriers. Under the combined action of the two effects, the MoSe»/defect-rich ZnIn2S4/CdSe dual Z-scheme photocatalyst presents a significantly improved photocatalytic water splitting to hydrogen performance, and a practical application prospect.

SUMMARY

[06] An objective of the present disclosure is to provide a MoSez/defect-rich Znln,S4/CdSe dual Z-scheme photocatalyst with efficient visible-light-driven photocatalytic water splitting to hydrogen performance.

[07] The objective of the present disclosure is achieved by the following technical solutions:

[08] (1) Preparation of MoSez/defect-rich ZnIn2S4/CdSe dual Z-scheme photocatalyst:

[09] | ZnIn2S4 prepared by a hydrothermal method is added into aqueous solution containing Naz:MoO4 with a concentration of 0.25-1.34 mM and Cd(CHs;COO), with a concentration of

0.31-1.06 mM, and then ultrasonic dispersion. In addition, Se powder is added into 80 wt% hydrazine hydrate solution followed by stirring in water bath at 80°C to prepare a Se precursor solution with a concentration of 7.64-24.54 mM. The above two solutions are mixed at a volume ratio of 8:1 and then transferred into the Teflon reactor for hydrothermal reaction at 200-260°C for 12-30 hours. Finally, the resulting product was separated by centrifugation, washed and dried to obtain the MoSez/defect-rich ZnIn2S4/CdSe dual Z-scheme photocatalyst.

[10] (2) Photocatalytic water splitting to hydrogen performance test of the MoSez/defect-rich ZnIn2S4/CdSe dual Z-scheme photocatalyst:

[11] The prepared MoSez/defect-rich ZnIn2S4/CdSe dual Z-scheme photocatalyst was applied for photocatalytic water splitting to hydrogen. Specific test steps are as follows: 5 mg of the 3

MoSez/defect-rich ZnIn,S4/CdSe photocatalyst was dispersed in 100 mL aqueous solution 200927 containing 1.7616 g ascorbic acid sacrificial agent by ultrasonic, and then transferred into 250 mL closed photocatalytic reactor. The photocatalytic reaction was irradiated by visible light, and the hydrogen production rate was calculated by measuring the generated hydrogen using gas chromatography.

[12] (3) Photocatalytic water splitting to hydrogen cycling stability test of the MoSe»/defect-rich ZnIn2S4/CdSe photocatalyst:

[13] A reaction solution containing the photocatalyst after once photocatalytic reaction was poured out from the reactor, and added 1.7612 g ascorbic acid sacrificial agent followed by ultrasonic dispersion for 30 minutes. The reaction solution was added into the 250 mL closed reactor again, and the photocatalytic water splitting to hydrogen performance is tested following the same procedure in (2). The processes above are conducted 8 times in total.

[14] Compared with existing photocatalysts, the MoSez/defect-rich ZnIn:Sy/CdSe dual Z-scheme photocatalyst for photocatalytic water splitting to hydrogen disclosed in the present disclosure possesses the following advantages:

[15] (1) In the present disclosure, the MoSer/defect-rich ZnIn2S4/CdSe dual Z-scheme photocatalyst is a novel photocatalytic material combined by defect-rich ZnIn2S4 nanosheet, CdSe nanoparticle and MoSez nanosheet, and has excellent photocatalytic water splitting to hydrogen performance.

[16] (2) In the present disclosure, the generation of sulfur defect in the MoSedefect-rich ZnIn2S4/CdSe dual Z-scheme photocatalyst and the growth of CdSe and MoSez on defect-rich ZnIn2S4 are achieved in one-step hydrothermal process, and MoSe; and CdSe are bonded with unsaturated sulfur atoms on the surface of defect-rich ZnIn,S4 to form Mo-S bond and Cd-S bond, respectively. The special interfacial chemical bonds can ensure the structural stability of the composite photocatalyst, and more importantly, direct charge transfer channels can be created among the defect-rich ZnIn:S4, MoSez and CdSe, thus facilitating the Z-scheme charge transfer, and finally improving the photocatalytic water splitting performance.

BRIEF DESCRIPTION OF THE DRAWINGS

[17] FIG. 1 shows the water splitting to hydrogen performance of the MoSe»/defect-rich ZnIn2S4/CdSe photocatalyst prepared in Example 1 under visible light irradiation (A>420 nm);

[18] FIG. 2 shows the water splitting to hydrogen cycling stability diagram of the MoSe»/defect-rich ZnIn2S4/CdSe photocatalyst prepared in Example 1 under visible light irradiation (A>420 nm);

[19] FIG. 3 shows the transmission electron microscope and the high-resolution transmission 4 electron microscope image of the MoSe»/defect-rich ZnIn2S4/CdSe photocatalyst prepared in 200927 Example 1;

[20] FIG. 4 shows the electron paramagnetic resonance spectrum of the MoSe»/defect-rich ZnIn2S4/CdSe photocatalyst prepared in Example 1;

[21] FIG. 5 shows the Raman spectrum of the MoSez/defect-rich ZnIn,S4/CdSe photocatalyst prepared in Example 1;

[22] FIG. 6 shows the water splitting to hydrogen performance of the MoSe»/defect-rich ZnIn2S4/CdSe photocatalyst prepared in Example 2 under visible light irradiation (A>420 nm);

[23] FIG. 7 shows the water splitting to hydrogen cycling stability diagram of the MoSez/defect-rich ZnIn2S4y/CdSe photocatalyst prepared in Example 2 under visible light irradiation (A>420 nm);

[24] FIG. 8 shows the water splitting to hydrogen performance of the MoSe»/defect-rich ZnIn2S4/CdSe photocatalyst prepared in Example 3 under visible light irradiation (A>420 nm);

[25] FIG. 9 shows the water splitting to hydrogen cycling stability diagram of the MoSe»/defect-rich ZnIn2S4/CdSe photocatalyst prepared in Example 3 under visible light irradiation (A>420 nm).

DETAILED DESCRIPTION OF THE EMBODIMENTS

[26] The present disclosure is described in detail below in conjunction with the accompanying drawings and specific examples, but the accompanying drawings and the specific examples are only used as examples and do not limit the scope of the present disclosure in any way.

[27] Example 1

[28] First, 100 mg of the prepared ZnIn2S4, 0.0037 g of NazMoO4'2H:0 and 0.0043 g of Cd(CH:COO), 2H:0 were weighed and dissolved in 20 mL of deionized water, and then ultrasonic dispersed for 1 hour. In addition, 0.0037 g of Se powder was weighed and added into 80 wt% hydrazine hydrate solution, which was then dissolved in water bath at 80°C to obtain a purple transparent Se precursor solution. At last, the two solutions above were mixed at a volume ratio of 8:1 and stirred at room temperature for 30 minutes. Then, the resulting mixed solution was transferred into a 50 mL Teflon reactor and kept at 240°C for 24 hours, and finally cooled to room temperature naturally. The obtained products was washed by deionized water and ethanol for several times, separated by centrifugation, and dried in vacuum drying oven at 60°C for 4 hours to obtain the MoSez/defect-rich ZnIn2SyCdSe composite photocatalyst. The photocatalytic water splitting to hydrogen performance of the photocatalyst under visible light irradiation (A>420 nm) was shown in FIG. 1 of the specification. From FIG. 1, it can be seen that a water splitting to hydrogen rate of 70,781 umol-g!-h! was achieved by the photocatalyst under visible 200927 light irradiation. The photocatalytic water splitting to hydrogen cycling stability test results of the photocatalyst was shown in FIG. 2 of the specification. From FIG. 2, it can be seen that after continuous and cyclic use for 8 times within 32 hours, the photocatalytic water splitting to hydrogen rate of the photocatalyst remains about 97% of the first use. The transmission electron microscope image of the photocatalyst was shown in FIG. 3 of the specification. It can be observed from FIG. 3A that the MoSez/defect-rich ZnIn2S4/CdSe photocatalyst presents the flower-like microsphere morphology consisting of nanoparticles and nanosheets. From the high-resolution electron microscope image in FIG. 3B, the lattice fringes with spacing of 0.32 nm can be corresponded to the (102) crystal face of hexagonal-phase ZnIn»S4, and the lattice fringes with interplanar spacing of 0.35 nm in the granular structural region attached on the surface of ZnIn2S4 nanosheet can be corresponded to the (111) crystal face of hexagonal-phase CdSe. In addition, on the surface of the ZnIn2S4 nanosheet, some narrow lattice fringes with an interplanar spacing of 0.24 nm can also be found, which can be corresponded to the (103) crystal face of 2H-phase MoSez. The above results confirmed that the MoSez/defect-rich ZnIn2S4/CdSe photocatalyst was successfully prepared, and CdSe and MoSez were grown on the surface of ZnIn2S4 in the form of nanoparticle and nanosheet, respectively. Electron paramagnetic resonance spectrum (EPR) of the photocatalyst was shown in FIG. 4 of the specification. It could be seen that there are abundant unsaturated coordination sulfur atoms existing in the MoSe»/defect-rich ZnIn,S4/CdSe composite photocatalyst. Raman spectrum of the photocatalyst was shown in FIG. 5 of the specification. As shown in the Raman spectrum of the ternary photocatalyst, in addition to the peaks corresponding to ZnIn:S4, CdSe and MoSez, peaks corresponding to Mo-S bond and Cd-S bond can also be distinguished, further proving that MoSez and CdSe grew on the surface of the defect-rich ZnIn2S4 by forming Mo-S bond and Cd-S bond, respectively.

[29] Example 2

[30] First, 100 mg of the prepared ZnIn2S4, 0.0037 g of NazMoO4'2H:0 and 0.0043 g of Cd(CH:COO), 2H:0 were weighed and dissolved in 20 mL of deionized water, and then ultrasonic dispersed for 1 hour. In addition, 0.0037 g of Se powder was weighed and added into 80 wt% hydrazine hydrate solution, which was dissolved in water bath at 80°C to obtain a purple transparent selenium precursor solution. At last, the two solutions above were mixed at a volume ratio of 8:1 and stirred at room temperature for 30 minutes. Then, the resulting mixed solution was transferred into a 50 mL Teflon reactor and kept at 220°C for 24 hours. After the reaction was completed and naturally cooling to room temperature, the product was washed by deionized water and ethanol repeatedly, separated by centrifugation, and finally dried in vacuum drying 6 oven at 60°C for 4 hours to obtain the MoSe»/defect-rich ZnlIn,S4/CdSe composite photocatalyst 997 Photocatalytic water splitting to hydrogen performance of the photocatalyst under visible light irradiation (A>420 nm) was shown in FIG. 6 of the specification. From FIG. 6, it can be seen that a hydrogen production rate of 66,804 umol-g'-h! was achieved by the photocatalyst under the visible light irradiation. Photocatalytic water splitting to hydrogen cycling stability test results of the photocatalyst was shown in FIG. 7 of the specification. From FIG. 7, after continuous and cyclic use for 8 times within 32 hours, the photocatalytic water splitting to hydrogen production rate of the photocatalyst remains about 95% of the first use.

[31] Example 3

[32] First, 100 mg of the prepared ZnIn2S4, 0.0037 g of Na:MoO4:2H:0 and 0.0072 g of Cd(CH:COO), 2H:0 were weighed and dissolved in 20 mL of deionized water, and then ultrasonic dispersed for 1 hour. In addition, 0.0045 g of Se powder was weighed and added into 80 wt% hydrazine hydrate solution, which was then dissolved in water bath at 80°C to obtain a purple transparent selenium precursor solution. At last, the two solutions above were mixed at a volume ratio of 8:1 and stirred at room temperature for 30 minutes. Then, the resulting mixed solution was transferred into a 50 mL Teflon reactor and kept at 240°C for 24 hours. After the reaction was completed and naturally cooling to room temperature, the product was washed by deionized water and ethanol repeatedly, separated by centrifugation, and finally dried in vacuum drying oven at 60°C for 4 hours to obtain the MoSey/defect-rich ZnIn2S4/CdSe composite photocatalyst. Photocatalytic water splitting to hydrogen performance of the photocatalyst under visible light irradiation (A>420 nm) was shown in FIG. 8 of the specification. From FIG. 8, it can be seen that a hydrogen production rate of 69,434 umol-g”!-h"! was achieved by the photocatalyst under visible light irradiation. Photocatalytic water splitting to hydrogen cycling stability test results of the photocatalyst was shown in FIG. 9 of the specification. From FIG. 9, after continuous and cyclic use for 8 times within 32 hours, the photocatalytic water splitting to hydrogen production rate of the photocatalyst remains about 91% of the first use.

[33] The foregoing descriptions are only the preferred examples of the present disclosure, and all the equivalent changes and modifications made in accordance with the claims of the present disclosure shall fall within the scope of the present disclosure.

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Claims

WHAT IS CLAIMED IS: 500927

1. A MoSez/defect-rich ZnIn2S4/CdSe dual Z-scheme photocatalyst for photocatalytic water splitting to hydrogen, wherein the dual Z-scheme photocatalyst is obtained by using defect-rich ZnIn2S4 flower-like microsphere as substrate, and the defect-rich ZnIn2S4 substrate is modified by CdSe nanoparticle and MoSez nanosheet through Cd-S bond and Mo-S bond, respectively; a preparation method of the photocatalyst is as follows: adding ZnIn2S4 prepared by hydrothermal method into an aqueous solution containing Cd(CH;COO), with a concentration of 0.25-1.34 mM and NaMoO4 with a concentration of 0.31-1.06 mM, and then ultrasonic dispersion; Meanwhile, adding Se powder into 80% hydrazine hydrate solution for stirring and dissolving in water bath at 80°C to prepare a Se precursor solution with a concentration of 7.64-24.54 mM; finally, mixing the two solutions at a volume ratio of 8:1 and transferring into Teflon reactor, heating at 200-260°C for 12-30 hours, and then centrifugal washing and drying to obtain the MoSer/defect-rich ZnIn2S4/CdSe dual Z-scheme photocatalyst.

2. The MoSez/defect-rich Znln,S4/CdSe dual Z-scheme photocatalyst for photocatalytic water splitting to hydrogen according to claim 1, wherein a mass ratio of MoSez to CdSe is (3-6):4, and a mass ratio of a total mass of CdSe and MoSez to ZnIn2S4 is (3-9):100.

3. The MoSez/defect-rich ZnIn2SyCdSe dual Z-scheme photocatalyst for photocatalytic water splitting to hydrogen according to claim 1, wherein due to the special dual Z-scheme charge transfer mechanism and close interface bonding, the photocatalyst can be used for efficient visible-light-driven water splitting to hydrogen, a hydrogen production rate of the photocatalyst can reach 66,000-70,000 umol-g!-h!, and after circulation for 8 times within 32 hours, the photocatalytic water splitting to hydrogen efficiency of the photocatalyst still remains 91% to 97% of the first use.

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