阅读说明：本技术 一种NH2-MIL-125/TiO2复合光阳极材料及其制备方法和应用 (NH (hydrogen sulfide)2-MIL-125/TiO2Composite photo-anode material and preparation method and application thereof ) 是由 王秀通 池丽凤 南有博 徐慧 孙欣 黄彦良 于 2020-06-24 设计创作，主要内容包括：本发明涉及复合膜光阳极,尤其是涉及一种NH<Sub>2</Sub>-MIL-125/TiO<Sub>2</Sub>复合光阳极材料及其制备方法与应用。本发明通过溶剂热法将NH<Sub>2</Sub>-MIL-125颗粒负载到TiO<Sub>2</Sub>薄膜上,由此得NH<Sub>2</Sub>-MIL-125/TiO<Sub>2</Sub>复合光阳极。由NH<Sub>2</Sub>-MIL-125复合后的TiO<Sub>2</Sub>光阳极不仅提高了对可见光的利用率,还降低了电子-空穴对的复合率,在可见光照射下能使与之偶联的304不锈钢电位大大降至自腐蚀电位以下,表现出优越的光生阴极保护性能,有效减缓或抑制金属腐蚀。(The invention relates to a composite film photo-anode, in particular to NH 2 ‑MIL‑125/TiO 2 A composite photo-anode material and a preparation method and application thereof. The invention uses a solvothermal method to react NH 2 Loading of MIL-125 particles to TiO 2 On the film, thereby obtaining NH 2 ‑MIL‑125/TiO 2 And (4) a composite light anode. From NH 2 -MIL-125 compounded TiO 2 The photoanode not only improves the utilization rate of visible light, but also reduces the recombination rate of electron-hole pairs, can greatly reduce the potential of 304 stainless steel coupled with the photoanode to be below the self-corrosion potential under the irradiation of the visible light, shows excellent photoproduction cathodic protection performance, and effectively slows down or inhibits metal corrosion.)

1. NH (hydrogen sulfide)₂-MIL-125/TiO₂The preparation method of the composite photo-anode material is characterized by comprising the following steps: by solvothermal method on TiO₂Loading NH on the film₂-MIL-125 to obtain NH₂-MIL-125/TiO₂And (4) a composite light anode.

2. The process according to claim 1, wherein: adding TiO into the mixture₂The film is placed in a reaction kettle, synthetic NH is poured in₂-MIL-125, followed by solvothermal reaction, vacuum drying and collection.

3. The process according to claim 2, wherein: said synthesis of NH₂The mixed solution required for MIL-125 is: mixing N, N-Dimethylformamide (DMF) and absolute methanol, stirring at a constant speed for 15-30 min, adding 2-aminoterephthalic acid, stirring for 15-30 min, adding tetra-N-butyl titanate, and continuously stirring for 1-1.5 h for later use; wherein N, N-Dimethylformamide (DMF) and absolute methanol are mixed according to the volume ratio of (1: 1), the adding amount of 2-aminoterephthalic acid is 7.5-15 mmol, and the adding amount of tetrabutyl titanate is 2.5-5 mmol.

4. The process according to claim 1 or 2, wherein: the solvothermal reaction is carried out in an oven, the reaction temperature is 140-170 ℃, the reaction time is 20-72 hours, and then the reaction product is naturally cooled to the room temperature.

5. The method of claim 4, wherein: and soaking the composite light anode obtained after the solvent thermal reaction by excessive DMF and absolute methanol in sequence, washing after soaking, and vacuum drying at 60-100 ℃ for 12 hours.

6. The method of claim 5, wherein: soaking for 5-15 min each time, and washing with pure DMF and anhydrous methanol in sequence between two soaking times; after two times of soaking, the mixture is washed again by absolute methanol.

7. The process according to claim 1, wherein: the TiO2 film is an anatase TiO2 film obtained by high-temperature calcination.

8. NH prepared by the method of claim 1₂-MIL-125/TiO₂The composite photo-anode material is characterized in that: NH prepared by the process of claim 1₂-MIL-125 particles supported or nested on TiO₂A composite material is formed on the surface of the film.

9. Use of a material according to claim 7, characterized in that: the photoanode material is used as a working electrode and applied to the field of photoproduction cathode protection.

10. The use of claim 8, wherein: the photo-anode is applied to photo-generated cathodic protection for slowing or inhibiting metal corrosion.

Technical Field

The invention relates to a composite film photo-anode, in particular to NH₂-MIL-125/TiO₂A composite photo-anode material and a preparation method and application thereof.

Background

The ocean contains abundant resources, and with the rapid development of ocean economy, a large number of ocean engineering facilities such as ocean platforms, wharf steel piles and the like are needed. However, marine construction has to face the problem of corrosion of the material. Stainless steel, for example, while having good corrosion resistance in the atmosphere, is rapidly rusted in a marine environment containing a large amount of chlorine salts. The photo-generated cathodic protection technology is a novel environmental protection technology for performing corrosion protection on metal by utilizing photovoltaic effect, and specifically comprises the following steps: when the illumination condition and the energy condition are appropriate, electrons in a semiconductor valence band are excited and separated to form a photoproduction electron hole pair, the electrons migrate to protected metal through a lead and are enriched, so that the electrode potential of the metal is lower than the self-corrosion potential, the photoproduction cathode protection effect is achieved, and only solar energy is consumed in the protection process without loss of other energy sources and resources.

TiO₂The photocatalyst is widely applied to the fields of photocatalysis, batteries, sensors and the like due to the advantages of low toxicity, chemical stability, low cost, easy preparation and the like, and the application of the photocatalyst is limited due to the characteristics of high photon-generated carrier recombination rate and response to ultraviolet light only accounting for 5 percent of sunlight. Thus, TiO is applied to broad scholars₂The modification of (2) was intensively studied. Modification of TiO₂The band gap structure and the improvement of the utilization rate of the band gap structure on visible light and even infrared light, so that more electrons flow to the protected metal is the main idea for improving the protective performance of the photo-generated cathode.

Disclosure of Invention

The invention aims to provide NH₂-MIL-125/TiO₂A composite photo-anode material and a preparation method and application thereof.

In order to achieve the purpose, the invention adopts the technical scheme that:

NH (hydrogen sulfide)₂-MIL-125/TiO₂The preparation method of the composite photo-anode material adopts a solvothermal method to prepare the composite photo-anode material on TiO₂Loading NH on the film₂-MIL-125 to obtain NH₂-MIL-125/TiO₂And (4) a composite light anode.

Further, TiO is added₂The film is placed in a reaction kettle, synthetic NH is poured in₂-MIL-125, followed by solvothermal reaction, vacuum drying and collection.

Further, anatase type TiO is grown on the surface₂The substrate of the film is put into synthetic NH₂Carrying out solvothermal reaction on reaction liquid required by MIL-125 to obtain TiO₂NH grows on the surface₂Soaking and cleaning the-MIL-125 composite material by using an organic solvent, and drying in vacuum to finally obtain NH₂-MIL-125/TiO₂A composite photo-anode material.

Said synthesis of NH₂The mixed solution required for MIL-125 is: mixing N, N-Dimethylformamide (DMF) and absolute methanol, stirring at a constant speed for 15-30 min, adding 2-aminoterephthalic acid, stirring for 15-30 min, adding tetra-N-butyl titanate, and continuously stirring for 1-1.5 h for later use; wherein, N, N-Dimethylformamide (DMF) and absolute methanol are mixed according to the proportion of 1: 1, the adding amount of 2-amino terephthalic acid is 7.5-15 mmol, and the adding amount of tetra-n-butyl titanate is 2.5-5 mmol.

Further, the formation of NH₂The reaction solution required by the MIL-125 is prepared by mixing and stirring 30mL of N, N-Dimethylformamide (DMF) and 30mL of anhydrous methanol for 15-30 min to serve as a solvent, adding 7.5-15 mmol of 2-aminoterephthalic acid, stirring for 15-30 min, dropwise adding 2.5-5 mmol of tetra-N-butyl titanate, and continuously stirring for 1-1.5 h.

Said synthesis of NH₂-MIL-125/TiO₂And carrying out solvothermal reaction of the composite photo-anode in an oven at the reaction temperature of 140-170 ℃ for 20-72 h, naturally cooling to room temperature, and taking out the sample.

And soaking the composite light anode obtained after the solvent thermal reaction by excessive DMF and absolute methanol in sequence, washing after soaking, and vacuum drying at 60-100 ℃ for 12 hours.

Soaking for 5-15 min each time, and washing with pure DMF and anhydrous methanol in sequence between two soaking times; after two times of soaking, the mixture is washed again by absolute methanol.

The soaking, cleaning and vacuum drying by using the organic solvent comprises the steps of immersing the sample in enough DMF for 5-15 minutes, washing the sample for three times by using pure DMF after taking out to remove residual 2-amino terephthalic acid in the sample, washing the sample for one time by using anhydrous methanol, immersing the sample in enough anhydrous methanol for 5-15 minutes, washing the sample for three times by using pure anhydrous methanol after taking out to remove DMF in the sample, naturally drying the sample, putting the sample in a vacuum drying box, vacuumizing the vacuum drying box at 60-100 ℃, and performing 12 hours.

The TiO2 film is prepared by taking a titanium foil as a substrate through an anodic oxidation method and then calcining at high temperature to obtain an anatase TiO2 film, or is prepared by taking conductive glass as a substrate through a sol-gel method and a dip-coating method and then calcining at high temperature to obtain an anatase TiO2 film.

The TiO is₂The film can be prepared by anodic oxidation with titanium foil as matrix, and is prepared by cutting titanium foil into 1 × 4cm²After being cleaned and polished, the titanium sheet is taken as a positive electrode, a platinum sheet is taken as a negative electrode, and is immersed into electrolyte, the anode oxidation is carried out on a direct current power supply, and the titanium sheet is washed and dried and then is calcined at high temperature.

The electrolyte is a solution composed of deionized water, ammonium fluoride and ethylene glycol, wherein the mass fraction of ammonium fluoride in the ammonium fluoride aqueous solution is 3-7 wt.%; the volume ratio of the ethylene glycol to the ammonium fluoride aqueous solution is 9-20.

The anodic oxidation condition is that the voltage is 15-25V, and the electrolysis time is 1-2 h.

The TiO is₂The film can also be prepared by taking conductive glass as a substrate through a sol-gel method and a dip-coating pulling method, namely soaking the cleaned conductive glass into TiO according to the speed of 300-500 mu m/s₂Staying in the sol for 3-5 minutes, pulling out at the speed of 300-500 mu m/s, drying in a blast drying oven at 100 ℃ for 10-20 minutes for more than one layer cycle, repeating the steps of the dipping and pulling method, and obtaining TiO with different layers on the conductive glass substrate₂Coating, drying and calcining at high temperature.

The TiO is₂The sol is prepared by the following steps: under the condition of stirring, dropwise adding a solution B consisting of 1.8g of ultrapure water and 25ml of absolute ethyl alcohol into a solution A consisting of absolute ethyl alcohol, tetrabutyl titanate and diethanol amine, and aging for 24 hours for later use; wherein the mass ratio of tetrabutyl titanate, absolute ethyl alcohol, ultrapure water and diethanol amine in the sol is 1: 26.5: 2: 1.

the high-temperature calcination condition is that the temperature is increased at the speed of 5 ℃/min, the heat preservation temperature is 450-500 ℃, and the heat preservation time is 2-3 h.

NH (hydrogen sulfide)₂-MIL-125/TiO₂Composite photo-anode material and NH prepared by the method₂-MIL-125 particles supported or nested on TiO₂A composite material is formed on the surface of the film.

The material is applied, and the photoanode material is used as a working electrode and applied to the field of photoproduction cathode protection.

The photo-anode is applied to photo-generated cathodic protection for slowing or inhibiting metal corrosion.

NH as described above₂-MIL-125/TiO₂The photoproduction cathodic protection performance test of the composite photo-anode material is as follows: the test device is a double electrolytic cell consisting of a photoelectrolytic cell and a corrosion electrolytic cell, and the photoelectrolytic cell and the corrosion electrolytic cell are separated by a proton exchange membrane. Wherein the photolysis cell is filled with 0.1M Na₂S +0.2M NaOH hole trapping agent, and NH is connected as an electrode₂-MIL-125/TiO₂The composite light anode is provided with a quartz window at the outer side for passing a light source; the corrosion electrolytic cell was filled with 3.5 wt% NaCl solution to simulate seawater environment, and connected with a three-electrode system with protected metal 304 stainless steel (304SS) as the working electrode, calomel electrode (SCE) as the reference electrode, and Pt sheet as the counter electrode. The photo-anode and the protected metal are connected together through a lead between the double electrolytic cells to be used as a working electrode of an electrode system. Visible light is simulated by a 300W high-pressure xenon lamp (an ultraviolet light filter is added). And testing the electrochemical signal change of the metal before and after the metal is protected by using an electrochemical workstation.

The basic principle of the invention is as follows:

TiO due to difference in band structure₂And NH₂Decrease in the recombination rate of photogenerated electron-hole pairs after-MIL-125 binding, plus-NH₂The absorption of visible light is enhanced, more electrons are transferred to the protected metal 304SS from the composite light anode under the irradiation of the visible light, so that the electrode potential of the 304SS is shifted negatively, thereby realizing the photoproduction cathodic protection of the composite light anode to the metal and slowing or inhibiting the corrosion of the metal.

The invention has the advantages that:

the invention is based on NH₂-MIL-125 semiconductor-like properties, narrow bandgap energy level structure, porous structure, functional group-NH₂Etc. characteristics of NH₂-MIL-125/TiO₂The recombination rate of electron hole pairs in the composite light anode is reduced, the response to visible light is enhanced, and the photo-generated cathodic protection of 304SS is finally realized. The method specifically comprises the following steps:

1. NH coupled with 304SS under irradiation of visible light₂-MIL-125/TiO₂The open circuit potential of the composite photo-anode material is obviously lower than the self-corrosion potential of 304SS, the photo-generated cathode protection effect is obvious, and the corrosion of stainless steel in a solution rich in chloride ions can be effectively slowed down or inhibited.

2. After the visible light irradiation is stopped, the potential of the stainless steel electrode rises but is still obviously lower than the self-corrosion potential, which shows that the composite light anode still has long-time cathodic protection effect in a dark state.

3. Under the irradiation of visible light, the photocurrent density of the composite light anode is high, the recombination rate of photon-generated carriers is low, and more photon-generated electrons are separated and transferred to the surface of 304 SS.

4. The invention adopts the catalyst which has large specific surface area and contains-NH₂Modified NH₂-MIL-125 with TiO₂The light response range of the photo-anode is improved by compounding, so that the photo-generated cathodic protection efficiency of the composite photo-anode is improved.

5. Whether made by anodic oxidation₂The nano-tube film is also TiO prepared by a sol-gel method₂Coating with NH₂After the-MIL-125 is compounded, the better photoproduction cathodic protection effect can be achieved, which shows that NH₂MIL-125 has a certain universality in photo-generated cathodic protection.

Drawings

FIG. 1 is a diagram of TiO provided in an embodiment of the present invention₂Surface topography of nanotubes (SEM images).

FIG. 2 shows NH provided by an embodiment of the present invention₂-MIL-125/TiO₂Surface topography (SEM image) of the composite photoanode material.

FIG. 3 shows TiO before and after illumination according to an embodiment of the present invention₂Nanotube film and NH₂-MIL-125/TiO₂And (3) an open circuit potential diagram of the composite photo-anode material coupled with 304SS, wherein the abscissa is time(s) and the ordinate is voltage (V vs.

FIG. 4 shows TiO before and after illumination provided by the embodiment of the present invention₂Nanotube film and NH₂-MIL-125/TiO₂The abscissa of the transient photocurrent curve of the composite photoanode material coupled with 304 stainless steel is time(s), and the ordinate of the transient photocurrent curve is photocurrent density (mu A-cm)^-2)。

FIG. 5 shows TiO provided in an embodiment of the present invention₂Surface topography of the coating (SEM picture).

FIG. 6 shows NH provided by an embodiment of the present invention₂-MIL-125/TiO₂Surface topography (SEM image) of the composite photoanode material.

FIG. 7 shows TiO before and after Opening (ON) and closing (OFF) light according to an embodiment of the present invention₂Coating and NH₂-MIL-125/TiO₂An open circuit potential diagram of the composite photoanode material coupled with 304 stainless steel, with time(s) on the abscissa and voltage (vvs. sce) on the ordinate.

FIG. 8 shows TiO before and after Opening (ON) and closing (OFF) light provided by an embodiment of the present invention₂Coating and NH₂-MIL-125/TiO₂The abscissa of the transient photocurrent curve of the composite photoanode material coupled with 304 stainless steel is time(s), and the ordinate of the transient photocurrent curve is photocurrent density (mu A-cm)^-2)。

Detailed Description

The invention is further explained below with reference to examples and figures.