Construction and application of a photocatalytic system containing homogeneous cocatalyst

Abstract

The application discloses a kind of construction and application of photocatalytic system containing homogeneous cocatalyst.The application constructs homogeneous cocatalyst by adding ligand in reaction system, prevents the deposition of cocatalyst Ni on the surface of titanium oxide catalyst, overcomes the influence of surface heterogeneity and interfacial diffusion of heterogeneous catalytic system, ensures the dispersion and balance of catalyst in system, and improves light absorption capacity.The steps of the application are as follows: (1) respectively take titanium oxide (TiO2) and nickel salt in reaction tube; (2) take alkali additive in the above reaction tube; (3) then add the mixed solution of methanol and acetonitrile; (4) measure the ligand and add it to the above solution; (5) replace with inert atmosphere; (6) irradiate the reaction tube with xenon lamp or LED lamp as light source, to obtain TiO2 photocatalyst with homogeneous nickel (II) complex as cocatalyst.The homogeneous nickel (II) complex cocatalyst of the application has the characteristics of balanced stability, has high catalytic activity, is used for dehalogenation coupling reaction, can obtain dehalogenation coupling product with high selectivity, and has simple preparation process and low manufacturing cost.

Description

Technical Field

[0001] This invention relates to the construction and application of a photocatalytic system containing a homogeneous co-catalyst, belonging to the field of photocatalytic materials and their preparation technology. Background Technology

[0002] Using semiconductors as catalysts to convert solar energy into chemical energy, achieving processes difficult to accomplish with traditional thermocatalysis, has garnered significant attention from researchers. However, semiconductor photocatalysis also faces numerous challenges, including low catalyst light-energy conversion efficiency, easy carrier recombination, low quantum yield, and low catalyst stability, significantly hindering its practical application. Currently, introducing co-catalysts onto semiconductors can often improve their light absorption properties, modulate the catalyst's band structure, and suppress the recombination of photogenerated electrons and holes. Therefore, adding homogeneous co-catalysts is beneficial for enhancing catalytic activity and improving the selectivity of target products.

[0003] Titanium oxide, due to its wide band gap, high energy and strong mobility of photogenerated carriers, exhibits strong redox capabilities and photocatalytic activity under ultraviolet light irradiation. However, its narrow absorption range and weak light absorption capacity significantly reduce its practical value. Furthermore, in heterogeneous catalytic systems, a phase interface exists between titanium oxide and the reaction substrate, leading to surface inhomogeneity and significant interphase diffusion resistance. Therefore, adding a homogeneous co-catalyst to construct redox active sites is an effective way to improve catalytic activity and target product selectivity. This invention constructs a homogeneous nickel(II) complex co-catalyst by adding ligands to the reaction system, preventing the deposition of Ni co-catalyst on the titanium oxide catalyst surface, overcoming the surface inhomogeneity and interphase diffusion effects of the heterogeneous catalytic system, ensuring catalyst dispersion and equilibrium in the system, and improving light absorption capacity. Its unique electronic band structure is suitable for dehalogenation coupling reactions, while also possessing excellent chemical stability, making it a novel catalytic material worthy of development and promotion in the field of photocatalytic materials.

[0004] Although Ni / TiO2 composite photocatalysts have been reported in the literature, such as [Xiangze Du, Yong Peng, Josep Albero, Dan Li, Changwei Hu, Hermenegildo García. Synthetic. Fuels from Biomass: Photocatalytic Hydrodecarboxylation of Octanoic Acid by NiNanoparticles Deposited on TiO2. ChemSusChem, 2022, 15(2): 202102107.], there are currently no reports on photocatalysts that use TiO2 as a support, nickel salt as the Ni ion source, and ligands to form homogeneous nickel(II) complex co-catalysts for dehalogenation coupling reactions. Summary of the Invention

[0005] The purpose of this invention is to provide an innovative, simple, easy-to-implement, and mild synthesis method that, by adding Ni ions to form a stable complex with ligands, prevents Ni from being deposited in situ on the TiO2 surface, thereby synthesizing a homogeneous nickel(II) complex cocatalyst material for photocatalytic titanium oxide.

[0006] The present invention provides the construction and application of a photocatalytic system containing a homogeneous co-catalyst, comprising the following: Using TiO2 as a support and nickel salt as a Ni ion source, a homogeneous nickel(II) complex co-catalyst is formed by adding ligands. Methanol is used as a reducing agent, and a basic salt is added to neutralize hydrogen protons. This catalyst is applied to a dehalogenation coupling reaction. Its preparation includes the following steps: (1) Add TiO2 and nickel salts to the reaction tube. The nickel salts include: nickel sulfate, nickel chloride, nickel nitrate, nickel bromide, nickel hydroxide, and nickel acetylacetonate. The molar ratio of TiO2 to nickel salts is 0.333~200; (2) Weigh out the alkali additive and add it to the reaction tube described in step (1). The alkali additive includes: potassium carbonate, potassium bicarbonate, potassium bisulfate, sodium carbonate, sodium bicarbonate, sodium bisulfate, sodium formate, and sodium acetate. The molar ratio of the alkali additive to TiO2 is 0.02~4; (3) Measure out methanol and add it to acetonitrile to obtain a methanol-acetonitrile solution. The volume ratio of acetonitrile to methanol is 0.667~30. (4) Add the methanol and acetonitrile mixture from step (3) to the reaction tube from step (2) in a volume of 1 mL; (5) Measure the ligands and add them to the reaction tube of step (4). The ligands include: o-phenanthroline, biimidazole, bipyridine, terpyridine, 2,4,6-tripyridyltriazine, tetraphenylporphyrin and different substituents of the above substances. The molar ratio of ligand to TiO2 is 0.013~3; (6) Replace the reaction tube obtained in step (5) with an inert gas of 0.05~3 MPa, including argon (Ar) and nitrogen (N2). (7) Irradiate the sample in the reaction tube of step (6) for 0.1~72 h with a xenon lamp or LED lamp as the light source to obtain a TiO2 homogeneous photocatalyst with nickel (II) complex as the co-catalyst.

[0007] In step (1), the nickel salt includes: nickel sulfate, nickel chloride, nickel nitrate, nickel bromide, nickel hydroxide, and nickel acetylacetonate. The molar ratio of TiO2 to the nickel salt is preferably 5 to 20.

[0008] In step (2), the alkali additive includes: potassium carbonate, potassium bicarbonate, potassium bisulfate, sodium carbonate, sodium bicarbonate, sodium bisulfate, sodium formate, and sodium acetate. The alkali additive is potassium carbonate, and its molar ratio with TiO2 is preferably 0.4 to 1.

[0009] In step (3), the volume ratio of acetonitrile to methanol is preferably 1.5 to 19.

[0010] In step (4), when the amount of TiO2 is 8.0 mg, the volume of the mixed solution is preferably 1 to 1.5 mL.

[0011] In step (5), the ligands include: o-phenanthroline, biimidazole, bipyridine, terpyridine, 2,4,6-tripyridyltriazine, tetraphenylporphyrin, and different substituent products of the above substances. The ligand is o-phenanthroline, and the preferred molar ratio of the ligand to TiO2 is 0.05~0.2.

[0012] In step (6), the gas introduced into the reaction tube is preferably N2 at 0.1~1 MPa.

[0013] In step (7), a xenon lamp is used as the light source to irradiate the sample in the reaction tube of step (6) for a certain period of time to obtain a TiO2 homogeneous photocatalyst with nickel (II) complex as the co-catalyst, wherein the irradiation time is preferably 1~6 h.

[0014] The nickel(II) complex prepared by the above method is a TiO2 photocatalyst system with homogeneous co-catalyst.

[0015] The application of the above catalytic system in photocatalytic dehalogenation coupling reaction.

[0016] This invention presents the first homogeneous TiO2 photocatalyst using a nickel(II) complex as a cocatalyst. By adding ligands to the reaction system, a homogeneous cocatalyst is constructed, preventing the deposition of Ni cocatalyst on the surface of the titanium oxide catalyst. This overcomes the effects of surface inhomogeneity and interphase diffusion in heterogeneous catalytic systems, ensuring the dispersion and equilibrium of the catalyst within the system, and broadening the spectral response range. It also improves light absorption capacity. The preparation method of this invention is simple, the reaction process is easily controlled, and the homogeneous photocatalytic titanium oxide cocatalyst composite photocatalyst exhibits high catalytic activity. Its unique electronic band structure is suitable for dehalogenation coupling reactions, while also possessing excellent chemical stability.

[0017] The homogeneous nickel(II) complex cocatalyst of the present invention has the characteristics of being balanced and stable, and has high catalytic activity. When used in dehalogenation coupling reaction, it can obtain dehalogenation coupling products with high selectivity. Moreover, the preparation process is simple and the manufacturing cost is low. Attached Figure Description

[0018] Figure 1 The images show the XRD patterns of the catalysts before and after the reaction in Example 1. They correspond to the TiO2 catalyst before the reaction, the homogeneous TiO2 catalyst with nickel complex as a co-catalyst after the reaction (with ligands), and the Ni / TiO2 catalyst after the reaction (without ligands), respectively.

[0019] Figure 2 The images show HAADF-STEM and STEM-EDS spectra of the catalyst after the reaction in Example 1. Figure 2 a~b are the homogeneous TiO2 catalysts (with ligands) prepared in Example 1, using nickel complexes as co-catalysts. Figure 2 c~d are HAADF-STEM and STEM-EDS images of the Ni / TiO2 catalyst (without ligand) prepared in Example 1. Detailed Implementation

[0020] Unless otherwise specified, the experimental methods used in the following embodiments of the present invention are conventional methods.

[0021] Unless otherwise specified, all materials and reagents used in the following embodiments of the present invention are commercially available.

[0022] The initial reactants used in the following embodiments of the present invention are commercially available analytical grade pharmaceutical products.

[0023] In the following embodiments of the present invention, the crystal structure of the prepared material was tested using a Malvern PANalytical Empirean X-ray diffractometer (XRD) (Cu Kα rays, voltage 40 kV, current 20 mA); the morphology and elemental composition of the prepared material were tested using a Talos F200X equipped with an energy-dispersive spectrometer (EDS) (accelerating voltage 200 kV) and an EDS spectrometer.

[0024] Example 1: Preparation of a homogeneous TiO2 photocatalyst using a nickel(II) complex coordinated with o-phenanthroline as a cocatalyst: 8.0 mg TiO2, 39.4 mg nickel sulfate hexahydrate, and 34.6 mg potassium carbonate were weighed and added to a transparent quartz reaction tube; 0.1 mL of methanol was measured and then added to 1 mL of acetonitrile to obtain a methanol-acetonitrile solution; 1 mL of the above methanol-acetonitrile mixture and 2.3 μL of o-phenanthroline were measured and added to the above reaction tube; N2 at 0.3 MPa was introduced into the reaction tube; finally, the sample was irradiated with a xenon lamp for 1 h to obtain a homogeneous TiO2 photocatalyst using a nickel(II) complex as a cocatalyst. The molar ratio of the Ni(II) complex to TiO2 was 0.15:0.10.

[0025] The process and conditions are the same as in Example 1 above, except that o-phenanthroline is not added; when o-phenanthroline is not added, Ni is deposited on TiO2 to obtain a Ni / TiO2 heterogeneous photocatalyst.

[0026] Example 2: Preparation of a homogeneous TiO2 photocatalyst using a biimidazole-coated nickel(II) complex as a cocatalyst: 8.0 mg TiO2, 39.4 mg nickel sulfate hexahydrate, and 34.6 mg potassium carbonate were weighed and added to a transparent quartz reaction tube; 0.1 mL of methanol was measured and then added to 1 mL of acetonitrile to obtain a methanol-acetonitrile solution; 1 mL of the above methanol-acetonitrile mixture and 1.5 μL of biimidazole were measured and added to the above reaction tube; N2 at 0.3 MPa was introduced into the reaction tube; finally, the sample was irradiated with a xenon lamp for 1 h to obtain a homogeneous TiO2 photocatalyst using a nickel(II) complex as a cocatalyst. The molar ratio of the Ni(II) complex to TiO2 was 0.15:0.10.

[0027] The process and conditions are the same as in Example 2 above, except that biimidazole is not added; when biimidazole is not added, Ni is deposited on TiO2 to obtain a Ni / TiO2 heterogeneous photocatalyst.

[0028] Example 3: Preparation of a homogeneous TiO2 photocatalyst using a nickel(II) complex coordinated with o-phenanthroline as a cocatalyst: 8.0 mg TiO2, 23.8.0 mg nickel chloride hexahydrate, and 34.6 mg potassium carbonate were weighed and added to a transparent quartz reaction tube; 0.1 mL of methanol was measured and then added to 1 mL of acetonitrile to obtain a methanol-acetonitrile solution; 1 mL of the above methanol-acetonitrile mixture and 2.3 μL of o-phenanthroline were measured and added to the above reaction tube; N2 at 0.3 MPa was introduced into the reaction tube; finally, the sample was irradiated with a xenon lamp for 1 h to obtain a homogeneous TiO2 photocatalyst using a nickel(II) complex as a cocatalyst. The molar ratio of the Ni(II) complex to TiO2 was 0.15:0.10.

[0029] The process and conditions are the same as in Example 3 above, except that o-phenanthroline is not added; when o-phenanthroline is not added, Ni is deposited on TiO2 to obtain a Ni / TiO2 heterogeneous photocatalyst.

[0030] Example 4: Preparation of a homogeneous TiO2 photocatalyst using a nickel(II) complex coordinated with o-phenanthroline as a cocatalyst: 8.0 mg TiO2, 39.4 mg nickel sulfate hexahydrate, and 20.5 mg sodium acetate were weighed and added to a transparent quartz reaction tube; 0.1 mL of methanol was measured and then added to 1 mL of acetonitrile to obtain a methanol-acetonitrile solution; 1 mL of the above methanol-acetonitrile mixture and 2.3 μL of o-phenanthroline were measured and added to the above reaction tube; N2 at 0.3 MPa was introduced into the reaction tube; finally, the sample was irradiated with a xenon lamp for 1 h to obtain a homogeneous TiO2 photocatalyst using a nickel(II) complex as a cocatalyst. The molar ratio of the Ni(II) complex to TiO2 was 0.15:0.10.

[0031] The process and conditions are the same as in Example 4 above, except that o-phenanthroline is not added; when o-phenanthroline is not added, Ni is deposited on TiO2 to obtain a Ni / TiO2 heterogeneous photocatalyst.

[0032] Example 5: Preparation of a homogeneous TiO2 photocatalyst using a nickel(II) complex coordinated with o-phenanthroline as a cocatalyst: 8.0 mg TiO2, 39.4 mg nickel sulfate hexahydrate, and 34.6 mg potassium carbonate were weighed and added to a transparent quartz reaction tube; 0.1 mL of methanol was measured and then added to 1 mL of acetonitrile to obtain a methanol-acetonitrile solution; 1 mL of the above methanol-acetonitrile mixture and 3.45 μL of o-phenanthroline were measured and added to the above reaction tube; N2 at 1.5 MPa was introduced into the reaction tube; finally, the sample was irradiated with a xenon lamp for 1 h to obtain a homogeneous TiO2 photocatalyst using a nickel(II) complex as a cocatalyst. The molar ratio of the Ni(II) complex to TiO2 was 0.15:0.10.

[0033] Example 6: Preparation of a homogeneous TiO2 photocatalyst using a biimidazole-coated nickel(II) complex as a cocatalyst: 8.0 mg TiO2, 39.4 mg nickel sulfate hexahydrate, and 34.6 mg potassium carbonate were weighed and added to a transparent quartz reaction tube; 0.1 mL of methanol was measured and then added to 1 mL of acetonitrile to obtain a methanol-acetonitrile solution; 1 mL of the above methanol-acetonitrile mixture and 3 μL of biimidazole were measured and added to the above reaction tube; N2 at 0.3 MPa was introduced into the reaction tube; finally, the sample was irradiated with a xenon lamp for 1 h to obtain a homogeneous TiO2 photocatalyst using a nickel(II) complex as a cocatalyst. The molar ratio of the Ni(II) complex to TiO2 was 0.15:0.10.

[0034] The process and conditions are the same as in Example 6 above, except that biimidazole is not added; when biimidazole is not added, Ni is deposited on TiO2 to obtain a Ni / TiO2 heterogeneous photocatalyst.

[0035] Example 7: Preparation of a homogeneous TiO2 photocatalyst using a nickel(II) complex coordinated with o-phenanthroline as a cocatalyst: 8.0 mg TiO2, 35.7 mg nickel chloride hexahydrate, and 34.6 mg potassium carbonate were weighed and added to a transparent quartz reaction tube; 0.1 mL of methanol was measured and then added to 1 mL of acetonitrile to obtain a methanol-acetonitrile solution; 1 mL of the above methanol-acetonitrile mixture and 2.3 μL of o-phenanthroline were measured and added to the above reaction tube; N2 at 0.3 MPa was introduced into the reaction tube; finally, the sample was irradiated with a xenon lamp for 1 h to obtain a homogeneous TiO2 photocatalyst using a nickel(II) complex as a cocatalyst. The molar ratio of Ni(II) complex to TiO2 was 0.15:0.10.

[0036] The process and conditions are the same as in Example 7 above, except that o-phenanthroline is not added; when o-phenanthroline is not added, Ni is deposited on TiO2 to obtain a Ni / TiO2 heterogeneous photocatalyst.

[0037] Example 8: Preparation of a homogeneous TiO2 photocatalyst using a nickel(II) complex coordinated with o-phenanthroline as a cocatalyst: 8 mg TiO2, 39.4 mg nickel sulfate hexahydrate, and 30.8 mg sodium acetate were weighed and added to a transparent quartz reaction tube; 0.1 mL of methanol was measured and then added to 1 mL of acetonitrile to obtain a methanol-acetonitrile solution; 1 mL of the above methanol-acetonitrile mixture and 2.3 μL of o-phenanthroline were measured and added to the above reaction tube; N2 at 0.3 MPa was introduced into the reaction tube; finally, the sample was irradiated with a xenon lamp for 1 h to obtain a homogeneous TiO2 photocatalyst using a nickel(II) complex as a cocatalyst. The molar ratio of the Ni(II) complex to TiO2 was 0.15:0.10.

[0038] The process and conditions are the same as in Example 8 above, except that o-phenanthroline is not added; when o-phenanthroline is not added, Ni is deposited on TiO2 to obtain a Ni / TiO2 heterogeneous photocatalyst.

[0039] Example 9: Preparation of ligand-free Ni / TiO2 heterogeneous photocatalyst: 8.0 mg TiO2, 39.4 mg nickel sulfate hexahydrate, and 34.6 mg potassium carbonate were weighed and added to a transparent quartz reaction tube; 0.1 mL of methanol was measured and then added to 1 mL of acetonitrile to obtain a methanol-acetonitrile solution; 1 mL of the above methanol-acetonitrile mixture was added to the above reaction tube; 0.3 MPa of N2 was introduced into the reaction tube; finally, the sample was irradiated with a xenon lamp for 1 h, and Ni was deposited on TiO2 to obtain the ligand-free Ni / TiO2 heterogeneous photocatalyst. The molar ratio of Ni(II) complex to TiO2 was 0.15:0.10.

[0040] Example 10: Preparation of nickel-free TiO2 photocatalyst: 8.0 mg TiO2 and 34.6 mg potassium carbonate were weighed and added to a transparent quartz reaction tube; 0.1 mL methanol was measured and then added to 1 mL acetonitrile to obtain a methanol-acetonitrile solution; 1 mL of the above methanol-acetonitrile mixture and 2.3 μL o-phenanthroline were measured and added to the above reaction tube; 0.3 MPa N2 was introduced into the reaction tube; finally, the sample was irradiated with a xenon lamp for 1 h to obtain the TiO2 photocatalyst.

[0041] Example 11: Preparation of nickel-free, ligand-free TiO2 photocatalyst: 8.0 mg TiO2 and 34.6 mg potassium carbonate were weighed and added to a transparent quartz reaction tube; 0.1 mL methanol was measured and then added to 1 mL acetonitrile to obtain a methanol-acetonitrile solution; 1 mL of the above methanol-acetonitrile mixture was measured and added to the above reaction tube; 0.3 MPa of N2 was introduced into the reaction tube; finally, the sample was irradiated with a xenon lamp for 1 h to obtain the TiO2 photocatalyst.

[0042] Example 12: Preparation of a homogeneous TiO2 photocatalyst using a nickel(II) complex coordinated with o-phenanthroline as a cocatalyst: 8.0 mg TiO2 and 39.4 mg nickel sulfate hexahydrate were weighed and added to a transparent quartz reaction tube; 0.1 mL of methanol was measured and then added to 1 mL of acetonitrile to obtain a methanol-acetonitrile solution; 1 mL of the above methanol-acetonitrile mixture and 2.3 μL of o-phenanthroline were measured and added to the above reaction tube; N2 at 0.3 MPa was introduced into the reaction tube; finally, the sample was irradiated with a xenon lamp for 1 h to obtain a homogeneous TiO2 photocatalyst using a nickel(II) complex as a cocatalyst. The molar ratio of Ni(II) complex to TiO2 was 0.15:0.10.

[0043] The process and conditions are the same as in Example 12 above, except that o-phenanthroline is not added; when o-phenanthroline is not added, Ni is deposited on TiO2 to obtain a Ni / TiO2 heterogeneous photocatalyst.

[0044] Example 13: Preparation of a homogeneous TiO2 photocatalyst using a nickel(II) complex coordinated with o-phenanthroline as a cocatalyst: 8.0 mg TiO2, 39.4 mg nickel sulfate hexahydrate, and 34.6 mg potassium carbonate were weighed and added to a transparent quartz reaction tube; 1 mL acetonitrile and 2.3 μL o-phenanthroline were measured and added to the above reaction tube; N2 at 0.3 MPa was introduced into the reaction tube; finally, the sample was irradiated with a xenon lamp for 1 h to obtain a homogeneous TiO2 photocatalyst using a nickel(II) complex as a cocatalyst. The molar ratio of Ni(II) complex to TiO2 was 0.15:0.10.

[0045] The process and conditions are the same as in Example 13 above, except that o-phenanthroline is not added; when o-phenanthroline is not added, Ni is deposited on TiO2 to obtain a Ni / TiO2 heterogeneous photocatalyst.

[0046] Example 14: Preparation of a homogeneous TiO2 photocatalyst using a nickel(II) complex coordinated with o-phenanthroline as a cocatalyst: 8.0 mg TiO2, 78.9 mg nickel sulfate hexahydrate, and 0.3 mg potassium carbonate were weighed and added to a transparent quartz reaction tube; 0.067 mL of methanol was measured and then added to 1 mL of acetonitrile to obtain a methanol-acetonitrile solution; 1 mL of the above methanol-acetonitrile mixture and 0.1 μL o-phenanthroline were measured and added to the above reaction tube; N2 at 0.3 MPa was introduced into the reaction tube; finally, the sample was irradiated with a xenon lamp for 1 h to obtain a homogeneous TiO2 photocatalyst using a nickel(II) complex as a cocatalyst. The molar ratio of nickel sulfate hexahydrate to TiO2 is 0.30:0.10, the molar ratio of potassium carbonate to TiO2 is 0.002:0.10, the volume ratio of acetonitrile to methanol is 0.067:0.10, and the molar ratio of o-phenanthroline to TiO2 is 0.013:0.10.

[0047] The process and conditions are the same as in Example 14 above, except that o-phenanthroline is not added; when o-phenanthroline is not added, Ni is deposited on TiO2 to obtain a Ni / TiO2 heterogeneous photocatalyst.

[0048] Example 15: Preparation of a homogeneous TiO2 photocatalyst using a nickel(II) complex coordinated with o-phenanthroline as a cocatalyst: 8.0 mg TiO2, 0.1 mg nickel sulfate hexahydrate, and 55.3 mg potassium carbonate were weighed and added to a transparent quartz reaction tube; 0.1 mL of methanol was measured and then added to 3 mL of acetonitrile to obtain a methanol-acetonitrile solution; 1 mL of the above methanol-acetonitrile mixture and 78 μL of o-phenanthroline were measured and added to the above reaction tube; N2 at 0.3 MPa was introduced into the reaction tube; finally, the sample was irradiated with a xenon lamp for 1 h to obtain a homogeneous TiO2 photocatalyst using a nickel(II) complex as a cocatalyst. The molar ratio of nickel sulfate hexahydrate to TiO2 is 0.0005:0.10, the molar ratio of potassium carbonate to TiO2 is 0.40:0.10, the volume ratio of acetonitrile to methanol is 3:0.10, and the molar ratio of o-phenanthroline to TiO2 is 0.3:0.10.

[0049] The process and conditions are the same as in Example 15 above, except that o-phenanthroline is not added; when o-phenanthroline is not added, Ni is deposited on TiO2 to obtain a Ni / TiO2 heterogeneous photocatalyst.

[0050] The catalysts obtained in Examples 1-15 were applied to the dechlorination coupling reaction of 2-chloroethanol. 1 mL of the homogeneous TiO2 photocatalyst with nickel(II) complexes as co-catalysts prepared in Examples 1-13 was measured into a transparent quartz reaction tube, and 0.2 mmol of the haloalcohol (2-chloroethanol) was added accordingly. After replacing the atmosphere with N2 in the reaction tube, 0.3 MPa of N2 was introduced. The sample was irradiated with a xenon lamp at 25°C for 6 h to obtain the dehalogenation coupling product (1,4-butanediol). The solution was filtered through a nylon filter (to remove solids from the system), and the filtrate was collected. The amount of product generated per unit time was quantified by chromatography. The reaction results are shown in the table below.

[0051]

[0052] Example 16: Preparation of a homogeneous TiO2 photocatalyst using a nickel(II) complex coordinated with o-phenanthroline as a cocatalyst: 8.0 mg TiO2, 39.4 mg nickel sulfate hexahydrate, and 34.6 mg potassium carbonate were weighed and added to a transparent quartz reaction tube; 0.1 mL of methanol was measured and then added to 1 mL of acetonitrile to obtain a methanol-acetonitrile solution; 1 mL of the above methanol-acetonitrile mixture and 2.3 μL of o-phenanthroline were measured and added to the above reaction tube; N2 at 0.3 MPa was introduced into the reaction tube; finally, the sample was irradiated with a xenon lamp for 1 h to obtain a homogeneous TiO2 photocatalyst using a nickel(II) complex as a cocatalyst. The molar ratio of the Ni(II) complex to TiO2 was 0.15:0.10.

[0053] The process and conditions are the same as in Example 1 above, except that the catalyst is used for the dechlorination coupling reaction of 1-chloroethanol as the reactant to obtain the target product 2,3-butanediol.

[0054] Example 17: Preparation of a homogeneous TiO2 photocatalyst using a nickel(II) complex coordinated with o-phenanthroline as a cocatalyst: 8.0 mg TiO2, 39.4 mg nickel sulfate hexahydrate, and 34.6 mg potassium carbonate were weighed and added to a transparent quartz reaction tube; 0.1 mL of methanol was measured and then added to 1 mL of acetonitrile to obtain a methanol-acetonitrile solution; 1 mL of the above methanol-acetonitrile mixture and 2.3 μL of o-phenanthroline were measured and added to the above reaction tube; N2 at 0.3 MPa was introduced into the reaction tube; finally, the sample was irradiated with a xenon lamp for 1 h to obtain a homogeneous TiO2 photocatalyst using a nickel(II) complex as a cocatalyst. The molar ratio of the Ni(II) complex to TiO2 was 0.15:0.10.

[0055] The process and conditions are the same as in Example 1 above, except that the catalyst is used for the deiodination coupling reaction of 2-iodoethanol as the reactant to obtain the target product 1,4-butanediol.

[0056] The catalyst obtained in Example 1 was applied to the dechlorination coupling of 1-chloroethanol and the deiodination coupling of 2-iodoethanol, corresponding to Examples 16 and 17, respectively. 1 mL of the TiO2 homogeneous photocatalyst with the nickel(II) complex prepared in Examples 16-17 as a co-catalyst was measured into a transparent quartz reaction tube, and 0.2 mmol of the aforementioned haloalcohols (1-chloroethanol or 2-iodoethanol) was added accordingly. After replacing the atmosphere with N2 in the reaction tube, 0.3 MPa of N2 was introduced. The samples were irradiated with a xenon lamp at 25°C for 6 h to obtain the dehalogenation coupling products. The products were filtered through a nylon filter (to remove solids from the system), and the filtrate was collected. The amount of product generated per unit time was quantified by chromatography. The reaction results are shown in the table below.

[0057]

[0058] like Figure 1 As shown, the three lines correspond to the XRD patterns of the TiO2 homogeneous photocatalyst prepared in this invention, with the nickel(II) complex as the co-catalyst. 2θ represents 25.2°, 37.8°, 48.0°, and 62.7°, corresponding to the (101), (004), (200), and (204) crystal planes of TiO2, respectively.

[0059] like Figure 2 The figures shown are HAADF-STEM and STEM-EDS images of the homogeneous TiO2 catalyst and the heterogeneous Ni / TiO2 catalyst prepared according to the present invention, using nickel complexes as co-catalysts. Figure 2 Figures a and b show that a very small amount of Ni nanoparticles are deposited on the TiO2 surface, and the particles are uniformly distributed. This indicates that Ni is stabilized in the liquid phase by ligands and is not easily deposited on the TiO2 surface. In contrast... Figure 2 Figures c and d show a large number of Ni nanoparticles deposited on the TiO2 surface, and the particles are relatively large. This indicates that Ni is deposited on the TiO2 surface in the absence of ligands.

[0060] It should also be noted that the above description details the construction and application of a photocatalytic system containing a homogeneous co-catalyst provided by this invention. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are merely for the purpose of helping to understand the method and core ideas of this invention. It should be pointed out that this invention is not limited to the specific details of the above embodiments. Without departing from the principles of this invention, it can be combined in any suitable way to make several improvements and modifications to this invention, and these improvements and modifications also fall within the protection scope of the claims of this invention. This invention will not further describe various possible combinations.

Claims

1. A method for constructing a photocatalytic system containing a homogeneous co-catalyst, characterized in that: Using TiO2 as a photocatalyst and nickel salt as a Ni ion source, a homogeneous nickel(II) complex co-catalyst is formed by adding ligands. Methanol is used as a reducing agent, and a basic salt is added to neutralize hydrogen protons. The preparation includes the following steps: (1) Add TiO2 and nickel salt to the photoreaction tube; The molar ratio of TiO2 to nickel salt is 0.333~200; (2) Weigh out the alkali additive and add it to the reaction tube described in step (1); the molar ratio of the alkali additive to TiO2 is 0.02~4; (3) Measure out methanol and acetonitrile and mix them to obtain a mixed solution. The volume ratio of acetonitrile to methanol is 0.667~150. (4) Add the mixed solution of methanol and acetonitrile from step (3) to the reaction tube from step (2). When the amount of TiO2 is 8.0 mg, the volume of the mixed solution is 0.5~2 mL. (5) Measure the ligand and add it to the reaction tube of step (4); The molar ratio of ligand to TiO2 is 0.005~3; the ligand includes: o-phenanthroline, biimidazole, bipyridine, terpyridine, 2,4,6-tripyridyltriazine, tetraphenylporphyrin and one or more of the products of the above substances after being substituted by different substituents; (6) Replace the reaction tube obtained in step (5) with an inert atmosphere gas of 0.05~3 MPa; (7) Using a xenon lamp and / or an LED lamp as the light source, irradiate the reaction material in the reaction tube of step (6) for 0.1~72 h to obtain a photocatalytic system containing a homogeneous co-catalyst.

2. The construction method as described in claim 1, characterized in that: In step (1), the nickel salt includes one or more of nickel sulfate, nickel chloride, nickel nitrate, nickel bromide, and nickel acetylacetone; the molar ratio of TiO2 to the nickel salt is 5 to 20.

3. The construction method as described in claim 1, characterized in that: In step (2), the alkali additive includes one or more of potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate, sodium formate, and sodium acetate; the molar ratio of the alkali additive to TiO2 is 0.4 to 1.

4. The construction method as described in claim 1, characterized in that: In step (3), the volume ratio of acetonitrile to methanol is 1.5 to 19.

5. The construction method as described in claim 1, characterized in that: In step (5), the ligand is o-phenanthroline; the molar ratio of the ligand to TiO2 is 0.05~0.

2.

6. The construction method as described in claim 1, characterized in that: In step (6), the inert atmosphere gas includes one or both of argon (Ar) and nitrogen (N2); the gas introduced into the reaction tube is N2 at a pressure of 0.1~1 MPa.

7. The construction method as described in claim 1, characterized in that: In step (7), a xenon lamp is used as the light source to irradiate the reaction material in the reaction tube of step (6) for 1-6 hours to obtain a photocatalytic system containing a homogeneous co-catalyst.

8. A photocatalytic system containing a homogeneous co-catalyst obtained by the construction method according to any one of claims 1-7.

9. The application of the photocatalytic system containing a homogeneous co-catalyst as described in claim 8 in photocatalytic dehalogenation coupling reactions.

10. The application as described in claim 9, characterized in that: The reactant is chloroethanol, and the reaction conditions are: nitrogen as an inert protective gas, acetonitrile as a solvent, and reaction under a xenon lamp light source for 1-6 hours.

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