CN111187272B

CN111187272B - A class of aza-fused conjugated ladder polymers and their preparation methods and their application in catalyzing water splitting under visible light

Info

Publication number: CN111187272B
Application number: CN202010036882.2A
Authority: CN
Inventors: 徐航勋; 麻晓宇; 王磊; 张颖
Original assignee: University of Science and Technology of China USTC
Current assignee: University of Science and Technology of China USTC
Priority date: 2020-01-14
Filing date: 2020-01-14
Publication date: 2021-07-06
Anticipated expiration: 2040-01-14
Also published as: CN111187272A

Abstract

The invention provides a aza-condensed conjugated ladder-shaped polymer, which is obtained by polymerization reaction of 1,2,4, 5-benzene tetramine tetrahydrochloride and 2, 5-dihydroxy-1, 4-benzoquinone; or the compound is obtained by polymerization reaction of 1,2,4, 5-benzene tetramine tetrahydrochloride and piperazine-2, 3,5, 6-tetraone; or the compound is obtained by polymerization reaction of 1,2,4, 5-benzene tetramine tetrahydrochloride and pyrene-4, 5,9, 10-tetraone. In the conjugated ladder-shaped polymer, the free twisting motion among the aromatic units along the skeleton is limited by the condensed ring structure, so that stable and effective conjugation can be provided, and the transmission of current carriers is facilitated. The conjugated trapezoidal polymer has good absorption in the visible light range, the energy band structure of the conjugated trapezoidal polymer meets the requirement of water photolysis to generate oxygen under the irradiation of visible light, and the conjugated trapezoidal polymer has excellent oxygen generation performance.

Description

Nitrogen-doped fused conjugated trapezoidal polymer, preparation method thereof and application of nitrogen-doped fused conjugated trapezoidal polymer in catalyzing water decomposition under visible light

Technical Field

The invention relates to the technical field of oxygen generation by photolysis of water, in particular to a nitrogen-doped fused conjugated trapezoidal polymer, a preparation method thereof and application of the polymer in catalyzing water decomposition under visible light.

Background

At present, nearly 80% of energy consumption in the world is derived from fossil energy, however, with increasing energy demand, limited fossil energy reserves and more severe environmental conditions, people are urgently required to develop a novel environment-friendly alternative energy. Solar energy, an inexhaustible energy, is widely concerned by people, wherein the photocatalytic decomposition of water by using a semiconductor catalyst is an effective method capable of directly converting solar energy into chemical energy, and is a new energy technology with great development potential.

The photocatalytic total hydrolysis reaction can be divided into an oxygen evolution reaction and a hydrogen evolution reaction, wherein the oxygen evolution reaction has more strict requirements than the hydrogen evolution reaction, and the photocatalytic total hydrolysis reaction relates to complex multi-electron transfer and needs to provide a large overpotential from the outside, and is a dynamic hysteresis process. Therefore, preparing an oxygen generating catalyst which can be efficient in the visible light range and is low in cost is always a research focus and a hot spot in the energy conversion field.

The catalysts which have been studied more deeply in the field of oxygen production by water decomposition under visible light catalysis at present are mainly divided into two types: the catalyst is inorganic metal catalysts such as tungsten trioxide, vanadium bismuth acid, ruthenium oxide, iridium oxide and the like, compared with polymer catalysts, the band gap regulation is difficult, a heterojunction system is usually required to be compositely constructed with other catalysts to obtain better oxygen production performance, and meanwhile, the metal catalysts have the defects of high cost, easy occurrence of a photo-corrosion phenomenon and the like, so that the industrial application of the metal catalysts is greatly limited; the other type is a polymer semiconductor catalyst based on nitrogen carbide, the semiconductor material has the advantages of low synthesis cost, adjustable band gap and the like, but because the visible light absorption is limited, the recombination is easy in the carrier migration process and the like, the oxygen generation kinetics is delayed, the catalytic activity is low, a method of loading a cocatalyst such as cobalt and the like is generally adopted, the catalytic activity is improved, and the industrial application is also limited.

Ladder polymers are a class of polymers whose main chain is composed of fused rings, with adjacent rings sharing two or more atoms in common, and are so named because of the ladder-like shape of the main chain. The conjugated ladder polymer (cLP) is a special ladder polymer with all condensed rings on the main chain being pi conjugated system, and is different from the conventional conjugated polymer in that the condensed ring structure limits the free twisting motion between the aromatic units along the skeleton, and the conjugated ladder polymer with completely coplanar skeleton has more stable and effective pi conjugated system, fast in-chain charge transmission, long exciton diffusion length and excellent thermal and mechanical properties due to the reduction of twisting defects. From the above perspective, due to the rigidity and the planar framework structure, the conjugated trapezoidal polymer is similar to a graphene nanoribbon, is a high-performance semiconductor material developed by combining the excellent charge performance and the band gap of graphene, and has great potential application value. The Journal of the American Chemical Society (2015, 137, page 15338) reports that a ladder polymer BBL (polyphenanthroline ladder polymer) is used as a photo-anode for photoelectrolysis of water, the BBL photo-anode shows good photoelectrochemical stability after 3 hours of water oxidation reaction and has no obvious degradation phenomenon, the material meets the condition of oxidizing water to generate oxygen thermodynamically, but actually the oxidation product is hydrogen peroxide, only on the basis of the BBL material, the composite layered titanium dioxide is used as an electron channel and supports a nickel-cobalt catalyst to decompose water to generate oxygen, and the yield is very low and is 20 nmol/h. The method has complex operation and low performance, and the cost is greatly increased by introducing metal and the like due to the requirement of external voltage, thereby being not beneficial to the application of the photocatalysis industry.

Disclosure of Invention

In view of the above, the technical problem to be solved by the present invention is to provide a class of aza-condensed and conjugated ladder-shaped polymers, a preparation method thereof, and an application thereof in catalyzing water decomposition under visible light, so as to realize photolysis of water to generate oxygen under visible light irradiation.

In order to solve the technical problems, the invention provides a nitrogen-thickening conjugated trapezoidal polymer which is obtained by polymerization reaction of 1,2,4, 5-benzene tetramine tetrahydrochloride and 2, 5-dihydroxy-1, 4-benzoquinone;

or the compound is obtained by polymerization reaction of 1,2,4, 5-benzene tetramine tetrahydrochloride and piperazine-2, 3,5, 6-tetraone;

or the compound is obtained by polymerization reaction of 1,2,4, 5-benzene tetramine tetrahydrochloride and pyrene-4, 5,9, 10-tetraone.

The invention provides a preparation method of a nitrogen-fused conjugated trapezoidal polymer, which comprises the following steps:

1,2,4, 5-benzene tetramine tetrahydrochloride and 2, 5-dihydroxy-1, 4-benzoquinone are subjected to polymerization reaction by taking polyphosphoric acid as a catalyst to prepare the aza-condensed conjugated trapezoidal polymer.

The reaction equation of the above reaction is as follows (taking the reaction temperature as an example at 180 ℃):

the structure of the prepared aza-condensed conjugated ladder-shaped polymer is shown as a formula I:

wherein n is the degree of polymerization, and specifically, n is 3-50.

Preferably, the temperature of the polymerization reaction is 170-200 ℃, more preferably 170-180 ℃, and still more preferably 180 ℃; the time of the polymerization reaction is preferably 10 to 18 hours, and more preferably 12 hours.

In the preparation process of the compound shown in the formula I, the catalyst only contains polyphosphoric acid and does not contain any other metal. The reaction temperature is only 170-200 ℃, the reaction condition is mild, and the synthesis time is short.

The amount of the polyphosphoric acid used is preferably 100 g.

The molar ratio of the 1,2,4, 5-benzenetetramine tetrahydrochloride to the 2, 5-dihydroxy-1, 4-benzoquinone is preferably 1: 1.

The polymerization reaction is preferably carried out under the protection of an inert gas, which is not particularly limited in the present invention, and may be any inert gas known to those skilled in the art, such as nitrogen or argon.

In the present invention, it is preferable that the polyphosphoric acid is subjected to a deoxidation pretreatment before the reaction.

In the present invention, it is preferable that the 1,2,4, 5-benzenetetraamine tetrahydrochloride is subjected to a dehydrochlorination pretreatment before the reaction.

Specifically, the polyphosphoric acid is aerated by using inert gas such as nitrogen or argon, and is heated for 20-24 hours, preferably 24 hours, at 100-120 ℃, preferably 120 ℃, so that the polyphosphoric acid is completely deoxidized.

Then adding 1,2,4, 5-benzene tetramine tetrahydrochloride into deoxidized polyphosphoric acid, and heating for 10-12 h, preferably 12h at 100-110 ℃, preferably 110 ℃ to remove hydrogen chloride completely.

Then 2, 5-dihydroxy-1, 4-benzoquinone is added to carry out polymerization.

In the invention, after the reaction is finished, the final product is obtained through post-treatment such as grinding, extraction and the like.

1,2,4, 5-benzene tetramine tetrahydrochloride and piperazine-2, 3,5, 6-tetraone are polymerized by taking sulfuric acid as a catalyst to prepare the aza-condensed conjugated ladder-shaped polymer.

the structure of the prepared aza-condensed conjugated trapezoidal polymer is shown as formula II:

wherein n is a polymerization degree, specifically, n is 3-50, preferably 10-50.

Preferably, the temperature of the polymerization reaction is 160-190 ℃, more preferably 160-180 ℃, and still more preferably 180 ℃; the time of the polymerization reaction is preferably 6 to 12 hours, and more preferably 8 hours.

In the preparation process of the compound shown in the formula I, the catalyst only contains a small amount of sulfuric acid and does not contain any other metal, so that the cost is low. The reaction temperature is only 160-190 ℃, the reaction condition is mild, and the synthesis time is short.

The amount of the sulfuric acid is preferably sulfuric acid: and (3) 160mL of N-methylpyrrolidone, wherein the total volume of N-methylpyrrolidone is 0.5-1 mL.

The sulfuric acid is preferably concentrated sulfuric acid, and more preferably concentrated sulfuric acid having a concentration of 98%.

The molar ratio of the 1,2,4, 5-benzenetetraamine tetrahydrochloride to the piperazine-2, 3,5, 6-tetraone is preferably 1: 1.

The polymerization reaction preferably uses N-methylpyrrolidone as a solvent.

In the invention, the N-methyl pyrrolidone is preferably subjected to deoxidation pretreatment before the reaction.

Then adding 1,2,4, 5-benzene tetramine tetrahydrochloride and piperazine-2, 3,5, 6-tetraone into the deoxidized N-methyl pyrrolidone, and dripping concentrated sulfuric acid under the ice bath condition to carry out polymerization reaction.

Preferably, after the reaction is finished, the final product is obtained through post-treatment such as suction filtration, extraction and the like.

The invention discloses a preparation method of aza-thick conjugated trapezoidal polymer, which comprises the following steps:

1,2,4, 5-benzene tetramine tetrahydrochloride and pyrene-4, 5,9, 10-tetraone are subjected to polymerization reaction by taking sulfuric acid as a catalyst to prepare the aza-condensed conjugated ladder-shaped polymer.

the structure of the prepared aza-condensed conjugated trapezoidal polymer is shown as formula III:

The molar ratio of the 1,2,4, 5-benzenetetramine tetrahydrochloride to pyrene-4, 5,9, 10-tetraone is preferably 1: 1.

The polymerization reaction preferably uses N-methylpyrrolidone as a solvent.

Then adding 1,2,4, 5-benzene tetramine tetrahydrochloride and pyrene-4, 5,9, 10-tetraone into the deoxidized N-methyl pyrrolidone, and dripping concentrated sulfuric acid under the ice bath condition to carry out polymerization reaction.

The invention provides an application of aza-condensed conjugated trapezoidal polymer with a structure shown in formula I, formula II or formula III as a catalyst for producing oxygen by water decomposition under catalysis of visible light.

The invention provides a method for producing oxygen by visible light catalytic water decomposition, wherein nitrogen-doped dense conjugated trapezoidal polymer with a structure shown in a formula I, a formula II or a formula III is used as a catalyst for producing oxygen by visible light catalytic water decomposition, and silver nitrate is used as an electronic sacrificial agent.

The invention provides a aza-condensed conjugated ladder-shaped polymer, which is obtained by polymerization reaction of 1,2,4, 5-benzene tetramine tetrahydrochloride and 2, 5-dihydroxy-1, 4-benzoquinone; or the compound is obtained by polymerization reaction of 1,2,4, 5-benzene tetramine tetrahydrochloride and piperazine-2, 3,5, 6-tetraone; or the compound is obtained by polymerization reaction of 1,2,4, 5-benzene tetramine tetrahydrochloride and pyrene-4, 5,9, 10-tetraone. In the conjugated ladder-shaped polymer prepared by the invention, the free twisting motion among the aromatic units along the skeleton is limited by the condensed ring structure, so that more stable and effective conjugation can be provided, and the transmission of current carriers is facilitated. The conjugated trapezoidal polymer has good absorption in the visible light range, the energy band structure of the conjugated trapezoidal polymer meets the requirement of water photolysis to generate oxygen under the irradiation of visible light, and the conjugated trapezoidal polymer has excellent oxygen generation performance.

In addition, the conjugated trapezoidal polymer is prepared by a one-step polymerization method, and the method is simple, mild in synthesis conditions and short in time consumption. The preparation process needs no introduction of any metal catalyst, and the cost is low.

Drawings

FIG. 1 is an infrared spectrum and a high resolution N1s X ray photoelectron spectrum of cLP-1, cLP-2 and cLP-3 prepared in an example of the present invention;

FIG. 2 is a diffuse reflectance chart of ultraviolet-visible near-infrared light of compounds cLP-1, cLP-2, and cLP-3 prepared in examples 1-3;

FIG. 3 is an optical band gap diagram of compounds cLP-1, cLP-2, and cLP-3 prepared in examples 1-3;

FIG. 4 is a scanning electron micrograph and an X-ray diffraction pattern of compounds cLP-1, cLP-2, cLP-3 prepared according to examples 1 to 3;

FIG. 5 is a graph showing the photolytic oxygen evolution performance of compounds cLP-1, cLP-2, and cLP-3 prepared in examples 1 to 3 in the visible light range.

Detailed Description

In order to further illustrate the present invention, the following examples are provided to describe the aza-condensed and conjugated ladder-shaped polymer of the present invention, its preparation method and its application in catalyzing water decomposition under visible light.

Example 1

100g of polyphosphoric acid (PAA) was added to a 150-ml two-neck flask equipped with a nitrogen inlet and outlet, air was blown into the polyphosphoric acid at a nitrogen flow rate of 30 ml/min, and the polyphosphoric acid was heated at 120 ℃ for 24 hours to completely deoxidize the polyphosphoric acid. The system temperature was then reduced to 50 deg.C and 568 mg of 1,2,4, 5-benzenetetraamine tetrahydrochloride was rapidly added to the deoxygenated polyphosphoric acid under a nitrogen atmosphere while heating the system to 120 deg.C for 12 hours to remove all hydrogen chloride from the 1,2,4, 5-benzenetetraamine tetrahydrochloride. Then 282 mg of 2, 5-dihydroxy-1, 4-benzoquinone was added to the mixture at 110 ℃ and the mixture was slowly heated (ramp rate 4 ℃/min) to 180 ℃ and held for 12 hours. The resulting viscous solution was cooled to room temperature and then transferred to a 500 ml beaker, and 400 ml of water was added to the beaker, stirred vigorously so that the polyphosphoric acid was well mixed with water, the mixed solution was centrifuged at 4000 rpm for 5 minutes to obtain a black precipitate, and the black precipitate was washed three times with water and methanol, respectively, and vacuum-dried at 100 ℃ for 24 hours. Drying the black solid, grinding into powder, performing Soxhlet extraction and cleaning with water and methanol as eluents for three days, and finally heating to 120 ℃ in a vacuum drying oven for two days to obtain cLP-1.

cLP-1 was subjected to elemental analysis testing, in which the content of carbon element was 68.96%, the content of nitrogen element was 26.72%, and the content of hydrogen element was 3.02%.

Example 2

1 g of 1,2,4, 5-benzenetetraamine tetrahydrochloride and 500 mg of piperazine-2, 3,5, 6-tetraone were added to a 200 ml round-bottomed flask under an inert atmosphere, and the round-bottomed flask was placed in an ice bath (temperature controlled at 0 ℃). 80 ml of N-methylpyrrolidone (NMP) was subjected to deoxidation treatment, and mixed with 0.5 ml of sulfuric acid, and the mixed solution was slowly added dropwise to the above round-bottom flask. The reaction apparatus was then brought to room temperature, stirred for 2 hours, then an oil bath was used instead of the ice-water bath and the whole reaction apparatus was heated to 180 ℃ and after 8 hours of continuous reaction, heating was stopped and the apparatus was cooled to room temperature. Adding water into a round-bottom flask to quench reaction, performing suction filtration on the suspension after the reaction by using a polytetrafluoroethylene (PTFE,0.22 micron) organic filter membrane to obtain a black solid product, performing Soxhlet extraction and cleaning on the black solid product by using methanol and deionized water as eluent respectively for three days, and finally heating to 120 ℃ in a vacuum drying oven to dry for two days to obtain a final product cLP-2.

cLP-2 was subjected to elemental analysis testing, in which the content of carbon element was 57.29%, the content of nitrogen element was 40.12%, and the content of hydrogen element was 1.98%.

Example 3

1 g of 1,2,4, 5-benzenetetraamine tetrahydrochloride and 922 mg of pyrene-4, 5,9, 10-tetraone were added to a 200 ml round-bottomed flask under an inert atmosphere, and the round-bottomed flask was placed in an ice bath (temperature controlled at 0 ℃). 80 ml of N-methylpyrrolidone (NMP) was subjected to deoxidation treatment, and mixed with 0.5 ml of sulfuric acid, and the mixed solution was slowly added dropwise to the above round-bottom flask. The reaction apparatus was then brought to room temperature, stirred for 2 hours, then an oil bath was used instead of the ice-water bath and the whole reaction apparatus was heated to 180 ℃ and after 8 hours of continuous reaction, heating was stopped and the apparatus was cooled to room temperature. Adding water into a round-bottom flask to quench reaction, performing suction filtration on the suspension after the reaction by using a polytetrafluoroethylene (PTFE,0.22 micron powder) organic filter membrane to obtain a black solid product, performing Soxhlet extraction and cleaning on the black solid product by using methanol and deionized water as eluent respectively for three days, and finally heating to 120 ℃ in a vacuum drying oven to dry for two days to obtain a final product cLP-3.

cLP-3 was subjected to elemental analysis testing, in which the carbon content was 80.11%, the nitrogen content was 16.97%, and the hydrogen content was 2.47%.

Infrared spectroscopic characterization was performed on the prepared compounds cLP-1, cLP-2, and cLP-3, and the results of the characterization are shown in FIG. 1a of FIG. 1. As can be seen from FIG. 1a, the three conjugated ladder polymers prepared by the present invention are 1250cm^-1And 1632cm^-1The left and right infrared absorption peaks were respectively attributed to stretching vibration of C ═ N bond in the aza-condensed ring and stretching vibration of C ═ C bond in the benzene ring, and the formation of the aza-condensed ring structure was successfully demonstrated in examples 1,2 and 3.

Fig. 1b is a high-resolution N1s X-ray photoelectron spectrum of compounds cLP-1, cLP-2 and cLP-3 prepared in examples 1 to 3, wherein absorption peaks at 400.4eV5, 400.2eV and 400.3eV correspond to N ═ C bonds in structures cLP-1, cLP-2 and cLP-3, respectively, and it is confirmed together with fig. 1a that cLP-1, cLP-2 and cLP-3 are successfully synthesized in examples 1,2 and 3.

FIG. 2 is a graph showing diffuse reflectance of ultraviolet-visible near-infrared light of the compounds cLP-1, cLP-2, and cLP-3 prepared in examples 1 to 3.

FIG. 3 is an optical band gap diagram of compounds cLP-1, cLP-2, and cLP-3 prepared in examples 1 to 3.

FIGS. 2 and 3 show that the three conjugated ladder polymers have better absorption in the visible light region, and the optical band gaps of cLP-1, cLP-2 and cLP-3 are 2.02eV, 1.66eV and 1.35eV respectively, which indicates that the conjugated ladder polymers have the capability of being used as visible light catalysts.

In FIG. 4, FIG. a is a SEM image of cLP-1 obtained in example 1, and it can be seen that the cLP-1 structure is a bulk structure formed by stacking a large number of nanoparticles; FIG. b is a scanning electron microscope photograph of cLP-2 from example 2, showing that the cLP-2 structure is a lamellar structure stacked by a plurality of nanosheets; FIG. c is a SEM image of cLP-3 obtained in example 3, and it can be seen that the cLP-3 structure is a randomly stacked block structure.

The structures jointly indicate that the conjugated trapezoidal polymers prepared by the invention have strong conjugated interaction.

FIG. d is an X-ray diffraction pattern of the conjugated trapezoidal polymers prepared in examples 1,2 and 3, and it can be seen that cLP-1, cLP-2 and cLP-3 all show broad diffraction peaks at around 27 ℃ due to interlayer stacking, indicating that cLP-1, cLP-2 and cLP-3 prepared by the present invention are amorphous polymers with strong conjugation interaction.

Example 4 photolysis of aquatic oxygen under visible light

A100 ml sealable, light transmitting quartz bottle was charged with 20 mg of the prepared ladder polymer, then 50 ml of deionized water and 84.9 mg of silver nitrate were added and the dispersion was sonicated for 30 minutes to achieve better dispersion of the material in water. The dispersion was bubbled with argon gas at a flow rate of 0.1 l/min for 30 minutes to remove the air from the container and solvent, then the container was quickly sealed with a rubber stopper and a sealing film, and placed under a light source having an intensity of 100 mw/cm: the light source was provided by a xenon lamp and a 420 nm filter was placed at the source emission to obtain visible light (λ >420 nm). The oxygen test temperature of the whole photolysis water is maintained at 25 +/-5 ℃.

And (3) extracting 1ml of gas from the quartz bottle by using a 1ml syringe at intervals of 1 hour, detecting and calculating the content of oxygen in the gas by using a gas chromatograph, multiplying the content by the total volume of the gas in the quartz bottle to obtain the total oxygen yield, and dividing the total oxygen yield by the used time and the mass of the used material to obtain the unit oxygen yield of the conjugated trapezoidal polymer material.

FIG. 5 is a graph showing the performance of photo-water decomposition with oxygen in the visible light range of cLP-1, cLP-2, and cLP-3 in this application example, and it was found through calculation that cLP-1 unit oxygen generation rate was 88.7. mu. mol/g/h, cLP-2 unit oxygen generation rate was 43.8. mu. mol/g/h, and cLP-3 unit oxygen generation rate was 32.1. mu. mol/g/h.

As can be seen from the above examples, the aza-condensed conjugated ladder polymer prepared by the present invention has excellent oxygen generating property.

The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

Claims

1. a class of aza condensed conjugated ladder polymers, is characterized in that, described aza condensed conjugated ladder polymers by 1,2,4,5-benzenetetramine tetrahydrochloride and piperazine-2 , 3,5,6-tetraketone is polymerized to obtain;

The aza-fused conjugated ladder polymer has the structure shown in formula II:

formula II;

Among them, n is 3~50.

2. The preparation method of a class of aza-fused and conjugated ladder polymers, comprising the following steps:

1,2,4,5-Phenyltetraamine tetrahydrochloride, and piperazine-2,3,5,6-tetraketone, with sulfuric acid as catalyst, carry out polymerization reaction to prepare aza-fused conjugated ladder polymerization thing;

The aza-fused conjugated ladder polymer has the structure shown in formula II:

formula II;

Among them, n is 3~50.

3 . The preparation method according to claim 2 , wherein the temperature of the polymerization reaction is 160-190° C., and the time of the polymerization reaction is 6-12 h. 4 .

4. Application of aza-fused conjugated ladder polymers as catalysts for visible light catalysis of water splitting and oxygen production;

The aza-fused conjugated ladder polymer is obtained by polymerizing 1,2,4,5-benzenetetramine tetrahydrochloride and 2,5-dihydroxy-1,4-benzoquinone;

Or obtained by polymerization reaction of 1,2,4,5-benzenetetramine tetrahydrochloride and piperazine-2,3,5,6-tetraketone;

Or obtained by polymerization of 1,2,4,5-benzenetetraamine tetrahydrochloride and pyrene-4,5,9,10-tetraketone;

The aza-fused and conjugated ladder polymers have the structures shown in formulas I to III:

formula I;

formula II;

formula III;

Among them, n is 3~50.

5. a method for visible light catalysis water splitting and oxygen production, it is characterized in that, with aza thick and conjugated ladder polymer as visible light catalysis water splitting oxygen generating catalyst, with silver nitrate as electron sacrificial agent;

formula I;

formula II;

formula III;

Among them, n is 3~50.