In-situ light-induced Janus Ni site catalyst as well as preparation method and application thereof

Abstract

The invention provides an in-situ light-induced Janus Ni site catalyst and a preparation method thereof, and the preparation method comprises the following steps: (1) dissolving Bi (NO3) 3.5 H2O in ethylene glycol, and adding KBr; carrying out hydrothermal treatment, washing and drying to obtain hydroxylated BiOBr, and marking the hydroxylated BiOBr as BOB-OH; (2) dispersing the BOB-OH powder in dilute ammonia water; after irradiation of a xenon lamp, washing and drying are carried out, and NH2-BOB-OH is obtained; (3) dispersing the NH2-BOB-OH powder in water, carrying out ultrasonic treatment, adding NiCl2. 6H2O, and carrying out ultrasonic treatment; carrying out photodeposition reaction under the irradiation of a full-arc xenon lamp; and washing, centrifuging and drying. The invention also provides application of the catalyst in photocatalytic energy conversion and environment purification. The catalyst provided by the invention not only can retain the advantages of a Janus structure, but also can effectively avoid the problem of low accuracy of a Janus structure active site catalyst constructed by a traditional method.

Description

Technical Field

[0001] The invention relates to the field of inorganic nanomaterials, and in particular to an in-situ light-induced Janus Ni site catalyst and a preparation method and application thereof. Background Art

[0002] Recently, Janus (two-sided) composite materials have been widely used in optical imaging, emulsion stabilizers, catalysis and drug delivery. The coupling interface of Janus structure can provide an effective strategy for the design of photoelectric catalysts, overcoming the problems of uneven distribution of active components, poor effective contact and low catalytic activity of traditional bimetallic active site catalysts. However, most of the current research is to construct Janus structure metal center catalysts based on traditional synthesis strategies, fix anchoring points, and change the types of metal atoms to construct Janus structure active site catalysts. Due to the random dispersion of the two metal atoms on the substrate, it often causes the aggregation of metal atoms, resulting in a large number of homonuclear diatomic, single atom and even multi-metal atomic configurations in the synthesized catalyst. There is still room for breakthroughs in the research on the precise synthesis of Janus metal active sites. Therefore, the precise construction of high-quality Janus structure metal center catalysts is still a very challenging research topic.

[0003] Different from the traditional synthesis strategy of Janus active sites, the present invention starts from the anchoring site and the anchoring metal atom in reverse, replaces the "traditional single anchoring site" with the "double anchoring site", and replaces the "traditional double metal atom" with the "single metal atom", to construct a new atomically dispersed Janus structure nickel active center catalyst on BiOBr with rich amino and hydroxyl groups on the surface. The Janus active center catalyst constructed by this strategy can not only retain the advantages of the Janus structure, but also effectively avoid the disadvantages of the above-mentioned construction of the Janus structure active site catalyst. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an in-situ light-induced Janus Ni site catalyst and a preparation method and application thereof, which can not only retain the advantages of the Janus structure, but also effectively avoid the problem of low precision of constructing Janus structure active site catalysts by traditional methods.

[0005] The present invention adopts the following technical solutions to solve the above technical problems:

[0006] A method for preparing an in-situ light-induced Janus Ni site catalyst comprises the following steps:

[0007] (1) Preparation of hydroxylated BiOBr

[0008] Take Bi(NO3)3·5H2O and dissolve it in ethylene glycol solution, stir until it is clear; then, add KBr and continue stirring for 2-4 hours; then, hydrothermally treat it at 115-125°C for 8-12 hours, wash and dry it to obtain hydroxylated BiOBr, marked as BOB-OH;

[0009] (2) Amino functionalization treatment

[0010] Disperse the BOB-OH powder obtained in step (1) in dilute ammonia water and stir evenly; irradiate with a xenon lamp for 1 to 3 hours, and then wash with deionized water; then dry at 45 to 55° C. for 10 to 14 hours to obtain NH2-BOB-OH;

[0011] (3) Preparation of Ni@NH2-BOB-OH

[0012] The NH2-BOB-OH powder obtained in step (2) is dispersed in water and subjected to ultrasonic treatment for 3 to 7 minutes; subsequently, a NiCl2·6H2O aqueous solution is added, and the obtained suspension is subjected to ultrasonic treatment for 8 to 12 minutes; after the ultrasonic treatment, stirring is started, and a photodeposition reaction is carried out under full arc irradiation of a 300W xenon lamp; finally, the mixture is washed with deionized water for several times, and after centrifugation, the obtained powder is collected and vacuum dried to obtain Ni@NH2-BOB-OH, i.e., the desired in situ photoinduced Janus Ni site catalyst.

[0013] As one of the preferred embodiments of the present invention, in the step (1), 0.97 g Bi(NO 3 ) 3 · 5H 2 O is weighed and dissolved in 60 mL ethylene glycol solution, and then 0.238 g KBr is added.

[0014] As one of the preferred embodiments of the present invention, in the step (2), 0.5 g of BOB-OH powder is weighed and dispersed in 20 mL of dilute ammonia water.

[0015] As one of the preferred embodiments of the present invention, in step (2), the method for obtaining the dilute ammonia water is: using ultrapure water to dilute 500 μL of 25% concentrated ammonia water to 20 mL.

[0016] As one of the preferred embodiments of the present invention, in the step (3), 200 mg NH2-BOB-OH is specifically weighed and dispersed in 80 mL of water. After ultrasonication, x mg NiCl2·6H2O aqueous solution is added; wherein x is 20, 40, 60, 80 or 100 mg, corresponding to obtaining different proportions of Ni@NH2-BOB-OH.

[0017] As one of the preferred embodiments of the present invention, in step (3), during the photodeposition reaction, the solution temperature is maintained at 30° C. by a circulating water system.

[0018] As one of the preferred embodiments of the present invention, in the step (3), the vacuum drying temperature is 70°C.

[0019] An in-situ light-induced Janus Ni site catalyst is prepared by the method.

[0020] An application of the above-mentioned in-situ light-induced Janus Ni site catalyst in photocatalytic energy conversion and synergistic environmental purification.

[0021] As one of the preferred embodiments of the present invention, the catalyst is used to photocatalyze CO2 reduction coupled with tetracycline (TC) oxidation.

[0022] Design ideas and principles:

[0023] In the traditional synthesis technology of Janus active sites, the "double metal atom" is mainly anchored on a "single active group" without a metal carrier. The random dispersion of the two metal atoms on the substrate causes the aggregation of metal atoms, resulting in the presence of a large number of homonuclear double atoms, single atoms and even polymetallic atoms in the synthesized catalyst.

[0024] The present invention utilizes the abundant amino groups and hydroxyl groups on NH2-BOB-OH (containing metal carrier) to anchor Ni atoms, forming "NH2-Ni" and "OH-Ni" dual-structure Ni sites (Janus Ni sites), respectively. The formed dual-structure Ni sites participate in CO2 reduction-coupled TC oxidation, respectively; and among them, NH2-Ni acts as a reduction site to reduce CO2, and OH-Ni acts as an oxidation site to oxidize TC.

[0025] The advantages of the present invention compared to the prior art are:

[0026] (1) The present invention constructs a novel atomically dispersed Janus structure nickel active center catalyst on BiOBr with rich amino and hydroxyl groups on the surface. The obtained catalyst can not only retain the advantages of the Janus structure (uniform distribution of active components, good effective contact and high catalytic activity), but also effectively avoid the problem of low precision of traditional construction of Janus structure active site catalysts;

[0027] (2) The present invention proposes a simple, green, in-situ photoreduction method to achieve atomically dispersed single atoms anchored on a BiOBr substrate material with rich surface active groups, and exhibits significant photocatalytic CO2 reduction coupled with tetracycline (TC) oxidation activity, which can be applied to the field of photocatalytic energy conversion and coordinated environmental purification;

[0028] (3) The catalyst preparation process of the present invention has mild conditions, does not require special equipment, is simple to operate, and the solvents used are non-toxic and harmless. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 : is an electron microscope structure diagram of the catalyst of the present invention (in the figure, Figure A is an electron microscope diagram of NH2-BOB-OH before Ni deposition, and Figure B is an electron microscope diagram of 0.2Ni@NH2-BOB-OH after Ni deposition);

[0030] Figure 2 It is the result of the photocatalytic CO2 reduction coupled with TC oxidation activity of a series of catalysts of the present invention;

[0031] Figure 3 It is the result of photocatalytic CO2 reduction coupled with TC oxidation activity of catalysts based on different substrate materials;

[0032] Figure 4 It is the result of the catalytic activity of the catalyst of the present invention in different reaction systems. DETAILED DESCRIPTION

[0033] The embodiments of the present invention are described in detail below. The embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments. At the same time, the reagent products and experimental methods used in the following embodiments, unless otherwise specified, are conventional reagents or methods in the art and will not be repeated.

[0034] Example 1

[0035] A preparation method of a catalyst "0.1Ni@NH2-BOB-OH" of this embodiment comprises the following steps:

[0036] (1) Preparation of hydroxylated BiOBr

[0037] 0.97 g Bi(NO3)3·5H2O was weighed and dissolved in 60 mL ethylene glycol solution and stirred until clear. Subsequently, 0.238 g KBr was added and stirred for 3 h. Next, the mixture was hydrothermally treated at 120 °C for 10 h, washed and dried to obtain hydroxylated BiOBr, which was labeled as BOB-OH.

[0038] (2) Amino functionalization treatment

[0039] Disperse 0.5 g of BOB-OH powder in 20 mL of dilute ammonia water (use ultrapure water to dilute 500 μL of 25% concentrated ammonia water to 20 mL), stir evenly; irradiate with a xenon lamp for 2 hours, wash with deionized water; then, dry at 50°C for 12 hours to obtain NH2-BOB-OH (amino-functionalized BOB-OH).

[0040] (3) Preparation of 0.1Ni@NH2-BOB-OH

[0041] 200 mg NH2-BOB-OH powder was dispersed in 80 mL water and ultrasonically treated for 5 min. Subsequently, 20 mg NiCl2·6H2O aqueous solution was added and the resulting suspension was ultrasonically treated for 10 min. After the ultrasonic treatment, stirring was started and the photodeposition reaction was carried out under full arc irradiation of a 300 W xenon lamp. During the reaction, the solution temperature was maintained at 30°C by a circulating water system. Finally, the solution was washed with deionized water several times and centrifuged, and the resulting powder was collected and vacuum dried at 70°C to obtain 0.1Ni@NH2-BOB-OH (NiCl2·6H2O: NH2-BOB-OH mass ratio = 0.1:1), which is the desired in situ photoinduced Janus Ni site catalyst.

[0042] Example 2

[0043] A preparation method of a catalyst "0.1Ni@NH2-BOB-OH" of this embodiment comprises the following steps:

[0044] (1) Preparation of hydroxylated BiOBr

[0045] 0.97 g Bi(NO3)3·5H2O was weighed and dissolved in 60 mL ethylene glycol solution and stirred until clear. Subsequently, 0.238 g KBr was added and stirred for 2 h. Next, the mixture was hydrothermally treated at 115 °C for 12 h, washed and dried to obtain hydroxylated BiOBr, which was labeled as BOB-OH.

[0046] (2) Amino functionalization treatment

[0047] 0.5 g of BOB-OH powder was dispersed in 20 mL of dilute ammonia water (500 μL of 25% concentrated ammonia water was diluted to 20 mL using ultrapure water) and stirred evenly; after irradiation with a xenon lamp for 1 hour, it was washed with deionized water; then, it was dried at 45°C for 14 hours to obtain NH2-BOB-OH (amino-functionalized BOB-OH).

[0048] (3) Preparation of 0.1Ni@NH2-BOB-OH

[0049] 200 mg NH2-BOB-OH powder was dispersed in 80 mL water and ultrasonically treated for 3 min. Subsequently, 20 mg NiCl2·6H2O aqueous solution was added and the resulting suspension was ultrasonically treated for 8 min. After the ultrasonic treatment, stirring was started and the photodeposition reaction was carried out under full arc irradiation of a 300 W xenon lamp. During the reaction, the solution temperature was maintained at 30°C by a circulating water system. Finally, the solution was washed with deionized water several times and centrifuged, and the resulting powder was collected and vacuum dried at 70°C to obtain 0.1Ni@NH2-BOB-OH (NiCl2·6H2O: NH2-BOB-OH mass ratio = 0.1:1), which is the desired in situ photoinduced Janus Ni site catalyst.

[0050] Example 3

[0051] A preparation method of a catalyst "0.1Ni@NH2-BOB-OH" of this embodiment comprises the following steps:

[0052] (1) Preparation of hydroxylated BiOBr

[0053] 0.97 g Bi(NO3)3·5H2O was weighed and dissolved in 60 mL ethylene glycol solution and stirred until clear; then, 0.238 g KBr was added and stirred continuously for 4 h; then, hydrothermal treatment was performed at 125°C for 8 h, and after washing and drying, hydroxylated BiOBr was obtained, which was labeled as BOB-OH.

[0054] (2) Amino functionalization treatment

[0055] 0.5 g of BOB-OH powder was dispersed in 20 mL of dilute ammonia water (500 μL of 25% concentrated ammonia water was diluted to 20 mL using ultrapure water) and stirred evenly; after irradiation with a xenon lamp for 3 h, it was washed with deionized water; then, it was dried at 55° C. for 10 h to obtain NH2-BOB-OH (amino-functionalized BOB-OH).

[0056] (3) Preparation of 0.1Ni@NH2-BOB-OH

[0057] 200 mg NH2-BOB-OH powder was dispersed in 80 mL water and ultrasonically treated for 7 min. Subsequently, 20 mg NiCl2·6H2O aqueous solution was added and the resulting suspension was ultrasonically treated for 12 min. After the ultrasonic treatment, stirring was started and the photodeposition reaction was carried out under full arc irradiation of a 300 W xenon lamp. During the reaction, the solution temperature was maintained at 30°C by a circulating water system. Finally, the solution was washed with deionized water several times and centrifuged, and the resulting powder was collected and vacuum dried at 70°C to obtain 0.1Ni@NH2-BOB-OH (NiCl2·6H2O: NH2-BOB-OH mass ratio = 0.1:1), which is the desired in situ photoinduced Janus Ni site catalyst.

[0058] Example 4

[0059] The preparation method of a catalyst "0.2Ni@NH2-BOB-OH" in this embodiment is basically the same as that in Example 1, except that: in step (3), 200 mg of NH2-BOB-OH powder is dispersed in 80 mL of water and ultrasonically treated for 5 min; then, 40 mg of NiCl2·6H2O aqueous solution is added, and the resulting suspension is ultrasonically treated for 10 min; after the ultrasonic treatment, stirring is started, and a photodeposition reaction is carried out under full arc irradiation of a 300 W xenon lamp; during the reaction, the solution temperature is maintained at 30°C by a circulating water system; finally, the solution is washed with deionized water several times, and after centrifugation, the resulting powder is collected and vacuum dried at 70°C to obtain 0.2Ni@NH2-BOB-OH (NiCl2·6H2O: NH2-BOB-OH mass ratio = 0.2:1), which is the desired in situ photoinduced Janus Ni site catalyst.

[0060] Example 5

[0061] The preparation method of a catalyst "0.3Ni@NH2-BOB-OH" in this embodiment is basically the same as that in Example 1, except that: in step (3), 200 mg NH2-BOB-OH powder is dispersed in 80 mL water and ultrasonically treated for 5 min; then, 60 mg of NiCl2·6H2O aqueous solution is added, and the resulting suspension is ultrasonically treated for 10 min; after the ultrasonic treatment, stirring is started, and a photodeposition reaction is carried out under full arc irradiation of a 300 W xenon lamp; during the reaction, the solution temperature is maintained at 30°C by a circulating water system; finally, the solution is washed with deionized water several times, and after centrifugation, the resulting powder is collected and vacuum dried at 70°C to obtain 0.3Ni@NH2-BOB-OH (NiCl2·6H2O: NH2-BOB-OH mass ratio = 0.3:1), which is the desired in situ photoinduced Janus Ni site catalyst.

[0062] Example 6

[0063] The preparation method of a catalyst "0.4Ni@NH2-BOB-OH" in this embodiment is basically the same as that in Example 1, except that: in step (3), 200 mg of NH2-BOB-OH powder is dispersed in 80 mL of water and ultrasonically treated for 5 min; then, 80 mg of NiCl2·6H2O aqueous solution is added, and the resulting suspension is ultrasonically treated for 10 min; after the ultrasonic treatment, stirring is started, and a photodeposition reaction is carried out under full arc irradiation of a 300 W xenon lamp; during the reaction, the solution temperature is maintained at 30°C by a circulating water system; finally, the solution is washed with deionized water several times, and after centrifugation, the resulting powder is collected and vacuum dried at 70°C to obtain 0.4Ni@NH2-BOB-OH (NiCl2·6H2O: NH2-BOB-OH mass ratio = 0.4:1), which is the desired in situ photoinduced Janus Ni site catalyst.

[0064] Example 7

[0065] The preparation method of a catalyst "0.5Ni@NH2-BOB-OH" in this embodiment is basically the same as that in Example 1, except that: in step (3), 200 mg NH2-BOB-OH powder is dispersed in 80 mL water and ultrasonically treated for 5 min; then, 100 mg of NiCl2·6H2O aqueous solution is added, and the resulting suspension is ultrasonically treated for 10 min; after the ultrasonic treatment, stirring is started, and a photodeposition reaction is carried out under full arc irradiation of a 300 W xenon lamp; during the reaction, the solution temperature is maintained at 30°C by a circulating water system; finally, the solution is washed with deionized water several times, and after centrifugation, the resulting powder is collected and vacuum dried at 70°C to obtain 0.5Ni@NH2-BOB-OH (NiCl2·6H2O: NH2-BOB-OH mass ratio = 0.5:1), which is the desired in situ photoinduced Janus Ni site catalyst.

[0066] Experimental Example 1

[0067] This experimental example is used to analyze the structural characteristics of the in-situ light-induced Janus Ni site catalyst of the present invention.

[0068] Taking the catalyst 0.2Ni@NH2-BOB-OH prepared in Example 4 as an example, its microstructure before and after Ni deposition was observed.

[0069] Figure 1 The electron microscope structure diagram of the catalyst of the present invention is shown in Figure A, which is an electron microscope diagram of NH2-BOB-OH before Ni deposition, and Figure B is an electron microscope diagram of 0.2Ni@NH2-BOB-OH after Ni deposition. Figure 1It can be seen that NH2-BOB-OH is a spherical structure composed of nanosheets. After Ni atoms are deposited, the nano-spherical structure of NH2-BOB-OH is still retained. Therefore, the catalyst of the present invention can retain the advantages of the Janus structure.

[0070] Experimental Example 2

[0071] This experimental example is used to verify the activity of the photocatalytic CO2 reduction coupled with TC oxidation of the catalyst of the present invention.

[0072] A series of in-situ light-induced Janus Ni site catalysts prepared by the present invention are respectively used in a coupled reaction system of photocatalytic CO2 reduction coupled with TC oxidation decomposition, and the specific process is as follows:

[0073] After adding 50 mg of photocatalyst 0.1 Ni@NH2-BOB-OH (Example 1), 0.2 Ni@NH2-BOB-OH (Example 4), 0.3 Ni@NH2-BOB-OH (Example 5), 0.4 Ni@NH2-BOB-OH (Example 6) or 0.5 Ni@NH2-BOB-OH (Example 7) to the photocatalytic reactor, 50 mL of TC aqueous solution (20 mg / L) was added and dispersed evenly by ultrasonication for 5 minutes. Then, the reactor was installed on the reaction system and the entire system was vacuum-drawn. Then, 50 mL of CO2 (purity of 99.999%) reaction gas was introduced into the system. Finally, the gas products of the photocatalytic reaction were determined using a gas chromatograph, and the absorbance of the TC supernatant after the catalytic reaction was measured using a UV-visible spectrophotometer.

[0074] Figure 2 The results of the photocatalytic CO2 reduction coupled with TC oxidation activity of a series of catalysts of the present invention (with BOB-OH and NH2-BOB-OH as controls). Figure 2 It can be seen that the photocatalytic performance of NH2-BOB-OH is significantly superior to that of BOB-OH; once Ni atoms are deposited, the photocatalytic performance of Ni@NH2-BOB-OH is significantly improved, and with the increase of Ni atom deposition, the photocatalytic CO2 reduction coupled TC oxidation activity of Ni@NH2-BOB-OH increases accordingly, until it increases to 0.2wt%, and the photocatalytic redox performance reaches the maximum value. However, with the further increase of Ni atom deposition, the photocatalytic redox performance of Ni@NH2-BOB-OH gradually decreases.

[0075] Experimental Example 3

[0076] This experimental example is used to verify the influence of different substrate materials on the photocatalytic activity of the catalyst of the present invention.

[0077] Referring to the method of Example 4, catalysts 0.2Ni@NH2-BOB-OH, 0.2Ni@BOB, 0.2Ni@BOB-OH, and 0.2Ni@NH2-BOB were prepared respectively, and their corresponding photocatalytic CO2 reduction coupled TC oxidation activities were measured (the measurement method was the same as that of Experimental Example 2).

[0078] The results are as follows Figure 3 As shown. Figure 3 It can be seen that 0.2Ni@NH2-BOB-OH exhibits superior photocatalytic redox performance than 0.2Ni@BOB, 0.2Ni@BOB-OH and 0.2Ni@NH2-BOB, which is mainly attributed to the Ni diatomic sites of the Janus structure anchored by dual active groups as the main factor for improving the photocatalytic redox performance.

[0079] Experimental Example 4

[0080] This experimental example is used to verify the influence of different reaction systems on the catalytic activity of the catalyst of the present invention.

[0081] Referring to the method of Example 2, different reaction systems (single TC oxidation system, coupled reaction system of CO2 reduction coupled TC oxidation, single CO2 reduction system) were constructed respectively, and 0.2Ni@NH2-BOB-OH catalyst was used to perform activity detection in the above systems respectively. Among them, the coupled reaction system corresponds to the coupled reaction system of photocatalytic CO2 reduction coupled TC oxidation in Experimental Example 2; CO2 is not added to the single TC oxidation system; and TC aqueous solution is not added to the single CO2 reduction system.

[0082] Test results such as Figure 4 As shown. Figure 4 It can be seen that the 0.2Ni@NH2-BOB-OH photocatalyst exhibits the best photocatalytic redox performance in the "coupled reaction system of photocatalytic CO2 reduction coupled with TC oxidation", which is significantly superior to other "single reaction systems", and further proves that the coupled reaction system achieves full utilization of carriers, thereby exhibiting significant photocatalytic oxidation performance. It can be seen that the Janus Ni site catalyst material prepared by the present invention has potential application prospects in synergistically alleviating the energy crisis and treating industrial wastewater.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an in-situ light-induced Janus Ni site catalyst, characterized in that: The steps include: (1) Preparation of hydroxylated BiOBr Take Bi(NO3)3·5H2O and dissolve it in ethylene glycol solution, stir until it is clear; then, add KBr and continue stirring for 2-4 hours; then, hydrothermally treat it at 115-125°C for 8-12 hours, wash and dry it to obtain hydroxylated BiOBr, marked as BOB-OH; (2) Amino functionalization treatment Disperse the BOB-OH powder obtained in step (1) in dilute ammonia water and stir evenly; irradiate with a xenon lamp for 1 to 3 hours, and then wash with deionized water; then dry at 45 to 55° C. for 10 to 14 hours to obtain NH2-BOB-OH; (3) Preparation of Ni@NH2-BOB-OH The NH2-BOB-OH powder obtained in step (2) is dispersed in water and subjected to ultrasonic treatment for 3 to 7 minutes; subsequently, a NiCl2·6H2O aqueous solution is added, and the obtained suspension is subjected to ultrasonic treatment for 8 to 12 minutes; after the ultrasonic treatment, stirring is started, and a photodeposition reaction is carried out under full arc irradiation of a 300W xenon lamp; finally, the mixture is washed with deionized water for several times, and after centrifugation, the obtained powder is collected and vacuum dried to obtain Ni@NH2-BOB-OH, i.e., the desired in situ photoinduced Janus Ni site catalyst.

2. The method for preparing the in-situ light-induced Janus Ni site catalyst according to claim 1, characterized in that: In the step (1), 0.97 g of Bi(NO3)3·5H2O was weighed and dissolved in 60 mL of ethylene glycol solution, and then 0.238 g of KBr was added.

3. The method for preparing the in-situ light-induced Janus Ni site catalyst according to claim 1, characterized in that: In the step (2), 0.5 g of BOB-OH powder is weighed and dispersed in 20 mL of dilute ammonia water.

4. The method for preparing an in-situ light-induced Janus Ni site catalyst according to claim 1, characterized in that: In the step (2), the dilute ammonia water is obtained by diluting 500 μL of 25% concentrated ammonia water to 20 mL using ultrapure water.

5. The method for preparing the in-situ light-induced Janus Ni site catalyst according to claim 1, characterized in that: In the step (3), 200 mg NH2-BOB-OH is specifically weighed and dispersed in 80 mL water. After ultrasonication, x mg NiCl2·6H2O aqueous solution is added; wherein x is 20, 40, 60, 80 or 100 mg, corresponding to obtaining different proportions of Ni@NH2-BOB-OH.

6. The method for preparing an in-situ light-induced Janus Ni site catalyst according to claim 1, characterized in that: In the step (3), during the photodeposition reaction, the solution temperature is maintained at 30° C. by a circulating water system.

7. The method for preparing an in-situ light-induced Janus Ni site catalyst according to claim 1, characterized in that: In the step (3), the vacuum drying temperature is 70°C.

8. An in-situ light-induced Janus Ni site catalyst, characterized in that: The method is prepared by any one of claims 1 to 7.

9. Use of the in-situ light-induced Janus Ni site catalyst as claimed in claim 8 in photocatalytic energy conversion and synergistic environmental purification.

10. The use according to claim 9, characterized in that: The catalyst is used to photocatalyze CO2 reduction coupled with tetracycline oxidation.

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