CN108911056B

CN108911056B - Preparation and application of {001} crystal face controllable exposure titanium dioxide photoelectrode

Info

Publication number: CN108911056B
Application number: CN201810245972.5A
Authority: CN
Inventors: 张亚男; 韩胜男; 黎雷; 赵国华
Original assignee: Tongji University
Current assignee: Tongji University
Priority date: 2018-03-23
Filing date: 2018-03-23
Publication date: 2021-06-04
Anticipated expiration: 2038-03-23
Also published as: CN108911056A

Abstract

The invention relates to preparation and application of a {001} crystal face controllable exposed titanium dioxide photoelectrode, wherein a titanium plate is used as a titanium source, hydrofluoric acid is used as a blocking agent, and TiO is grown in situ on a titanium substrate by a hydrothermal method₂The exposure ratio of the {001} crystal face of the flower-shaped microsphere structure is 0-100%, and the prepared {001} TiO is₂the/Ti photoelectrode can be applied to the photoelectrocatalysis oxidation degradation of dimethyl phthalate wastewater. Compared with the prior art, the {001} TiO with controllably exposed {001} crystal face prepared by the invention₂the/Ti photoelectrode has high-efficiency photoelectrocatalysis performance (the photocurrent density can reach 0.74mA/cm at most²) The highest removal rate of the dimethyl phthalate with the concentration of 5mg/L can reach 94.3 percent within 8 hours. The electrode material and the technology are suitable for the field of photoelectrocatalysis degradation of phthalate pollutants.

Description

Preparation and application of {001} crystal face controllable exposure titanium dioxide photoelectrode

Technical Field

The invention relates to the field of environmental pollution treatment technology and material chemistry, in particular to {001} TiO with controllably exposed {001} crystal face₂The application of the/Ti photoelectrode in removing phthalate through high-efficiency catalytic oxidation.

Background

Phthalate esters (PAEs) are a commonly used, artificially synthesized, typical endocrine disrupter seriously harmful to human health, and are widely used in industry as a plasticizer for synthetic rubber, paint solvents, and the like as a modification additive for plastics to increase plasticity and strength of the plastics. And PAEs have the characteristics of difficult water solubility, low volatility, low temperature resistance and the like, are used for producing pesticides, cosmetics, coatings, lubricants and the like, enter a human body through breathing, diet and skin contact in the process of using plastic products by human beings, and have important influence on the reproductive system, cardiovascular system, liver and endocrine system of the human body. PAEs are bonded with plastic molecules by van der waals force and hydrogen bonds, so that the PAEs are easily transferred into the environment along with the use of plastic products by human beings, widely exist in the atmosphere, soil, water and organisms, and become ubiquitous pollutants in the environment. Especially in China, the PAEs are used in large amount, the water environment pollution is serious, the PAEs in a plurality of water bodies seriously exceed the standard, the water safety and the life health are threatened, and the PAEs become one of the most concerned main pollutants in China at present. Dimethyl phthalate (DMP) is a typical phthalate, which is monitored in water bodies such as Yangtze river, yellow river, Huangpu river, Songhua river, nested lake and the like in China and effluent water of water plants, and from the investigation result, 5 DMPs and the like are mainly detected, and DMP, DBP and DOP are also listed as a blacklist of priority monitoring pollutants in China. Therefore, the method has important environmental significance for removing the DMP in the water body.

Based on TiO₂And the photoelectrocatalysis technology of semiconductor catalysts is proved to be capable of effectively removing phthalate pollutants in water. The photoelectric oxidation reaction is that in a photoelectrochemical system, an electric field is applied to promote photoproduction electrons to be transferred to a cathode, and the method is utilized to inhibit the simple recombination of electrons and holes, thereby improving the quantization efficiency of the photocatalytic oxidation. Because the photoelectrocatalysis reaction is an interface reaction, pollutants are diffused and adsorbed on the surface of the catalyst, and simultaneously, the catalytic oxidation reaction is immediately carried out. Therefore, the characteristics of the surface of the catalyst, the accumulation amount of holes, and the adsorption state of the catalyst on the surface are greatly influenced by the surface properties of the catalyst, thereby greatly influencing the path and rate of the entire reaction.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide the 001 TiO with the controllable exposed 001 crystal face₂The application of the Ti photoelectrode in the aspect of degrading organic pollutants by high-efficiency photoelectrocatalysis oxidation.

The purpose of the invention can be realized by the following technical scheme:

the preparation method of the titanium dioxide photoelectrode with controllable exposed {001} crystal face takes a titanium plate as a titanium source and hydrogen asHydrofluoric acid is used as a blocking agent, and TiO grows in situ on a titanium substrate by a hydrothermal method₂Flower-like microsphere structure, TiO₂The dimension is about 500nm to 1 μm, the shape is a flower-shaped microsphere structure, the exposure ratio of the {001} crystal face is 0-100%, and the following steps are specifically adopted:

(1) chemically polishing a titanium plate in polishing solution obtained by mixing nitric acid, hydrofluoric acid and water to remove surface grease, impurities and metal oxides;

(2) putting the chemically polished smooth titanium plate into a reaction liquid obtained by mixing hydrofluoric acid and water for hydrothermal reaction;

(3) and taking out the sample, cleaning, drying and calcining in an air atmosphere.

The volume ratio of the nitric acid to the hydrofluoric acid to the water in the step (1) is 2:1: 6-4: 1:6, and as a preferred embodiment, the volume ratio of the nitric acid to the hydrofluoric acid to the water is preferably 3:1: 6.

The volume ratio of the hydrofluoric acid to the water in the step (2) is 0.007: 25-0.027: 30, as a preferred embodiment, the volume ratio of the hydrofluoric acid to the water is preferably 0.027:30, the hydrothermal reaction temperature is 140-180 ℃, and the time is 0-4 h, as a preferred embodiment, the hydrothermal reaction temperature is 180 ℃, and the time is 4 h.

The temperature rise rate of the calcination is 1-5 ℃/min, the calcination temperature is 400-550 ℃, and the calcination time is 2-5 h.

Application of {001} crystal face controllable exposed titanium dioxide photoelectrode to {001} TiO₂a/Ti electrode is used as an anode, a platinum sheet is used as a cathode, a saturated calomel electrode is used as a reference electrode, a three-electrode system is adopted, a +0.2 to +0.8V bias voltage is applied, the photoelectrocatalysis oxidation degradation is carried out on dimethyl phthalate wastewater with the concentration of 5-10 mg/L under the illumination condition of ultraviolet light, and the light intensity under the illumination condition is 50-200W/cm². The degradation time is 3-8 h.

Compared with the prior art, the invention has the following advantages:

(1) the {001} TiO with controllably exposed {001} crystal face prepared by the invention₂The hydrofluoric acid in the precursor solution is used as a sealing agent and an etching agent. Between 0h and 4h, hydrofluoric acid isAnd the end capping agent of the 001 crystal face inhibits the growth of the 001 crystal face. Along with the increase of the hydrothermal time, the exposure proportion of the 001 crystal face gradually increases, and the exposure proportion of the 001 crystal face reaches 100% in 4h of the hydrothermal time, so that the most efficient photoelectrocatalysis performance is obtained. When the hydrothermal time is further increased, hydrofluoric acid starts to act as an etchant to etch the {001} crystal face, the exposure proportion of the {001} crystal face is gradually reduced, and when the hydrothermal time is 6 hours, the exposure proportion is 0.

(2) In-situ grown 001 TiO on titanium substrate₂Solves the problems that the powder photocatalyst is difficult to recycle and reuse in the catalysis process, and in addition, the in-situ growth improves the TiO₂Poor conductivity;

(3){001}TiO₂the photoelectrocatalysis oxidation system promotes the separation of catalyst photoproduction electron-cavity by applying bias voltage in a three-electrode system, and realizes high-efficiency photoelectrocatalysis oxidation.

Drawings

FIG. 1 shows 4h- {001} TiO prepared in example 1₂Scanning electron microscope images of the/Ti photoelectrode;

FIG. 2 is the 2h- {001} TiO prepared in example 2₂Scanning electron microscope images of the/Ti photoelectrode;

FIG. 3 shows {001} TiO prepared in examples 1 and 2₂In the process of degrading DMP by the Ti photoelectrode, a DMP concentration-initial concentration ratio and a time curve chart are obtained;

FIG. 4 shows {001} TiO prepared in examples 1 and 2₂And a corresponding first-order reaction kinetic analysis chart in the process of degrading DMP by the Ti photoelectrode.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.

Example 1

{001} TiO with controllably exposed {001} crystal face₂The preparation method of the/Ti photoelectrode specifically comprises the following steps:

(1) chemically polishing a titanium plate in a polishing solution mixed by nitric acid, hydrofluoric acid and water, wherein the proportion of the polishing solution is as follows: hydrofluoric acid: water volume ratio 3:1: 6.

(2) mixing 27uL (not less than 38 wt%) of hydrofluoric acid with 30mL of deionized water, stirring uniformly, transferring into a 100mL high-pressure reaction kettle, placing the titanium plate subjected to chemical polishing treatment in the step (1), sealing, and carrying out hydrothermal reaction in an oven at 180 ℃ for 4 hours.

(3) And (3) after the reaction in the step (2) is finished, cooling the reaction kettle at room temperature, washing with deionized water after being taken out, and naturally drying. In the air atmosphere, the heating rate is 3 ℃/min, the calcining temperature is 450 ℃, and the calcining time is 3 h. Thus obtaining 4h- {001} TiO₂a/Ti photoelectrode.

The morphology of the electrode was characterized by field emission scanning electron microscopy (Hitachi S-4800), see FIG. 1, which shows TiO in FIG. 1₂Mirror-like microspheres with nano-sized morphology and TiO₂Are uniformly distributed on the titanium substrate. Preparation of the resulting 4h- {001} TiO₂The {001} crystal face exposure ratio of the/Ti photoelectrode can reach nearly 100%.

Example 2

(2) mixing 27uL (not less than 38 wt%) of hydrofluoric acid with 30mL of deionized water, stirring uniformly, transferring into a 100mL high-pressure reaction kettle, placing the titanium plate subjected to chemical polishing treatment in the step (1), sealing, and carrying out hydrothermal reaction in an oven at 180 ℃ for 2 hours.

(3) And (3) after the reaction in the step (2) is finished, cooling the reaction kettle at room temperature, washing with deionized water after being taken out, and naturally drying. In the air atmosphere, the heating rate is 3 ℃/min, the calcining temperature is 450 ℃, and the calcining time is 3 h. Thus obtaining 2h- {001} TiO₂a/Ti photoelectrode.

The morphology of the electrode was characterized by field emission scanning electron microscopy (Hitachi S-4800), see FIG. 2, which shows TiO 2₂Flower-like microspheres with nano-sized morphology and TiO₂Are uniformly distributed on the titanium substrate. Preparation of the resulting 2h- {001} TiO₂The {001} crystal face exposure ratio of the/Ti photoelectrode was 30%.

Example 3

The 2h- {001} TiO prepared in example 2 was used₂The method comprises the following steps of performing efficient photodegradation on DMP simulation wastewater by a Ti photoelectrode (with the crystal face exposure ratio of 001 being 30%):

the photoelectric degradation DMP experiment is carried out in an electrochemical reaction tank, a sleeve cup with circulating water is additionally arranged, and the constant temperature of a reaction system is kept at 25 ℃. Adopting a three-electrode degradation system to degrade with {001} TiO₂The Ti electrode is a working electrode, the platinum sheet is a counter electrode, the distance between the working electrode and the counter electrode is 1cm, and the effective photoelectrode area is 3 multiplied by 5cm². With 0.1 mol. L^-1The sodium sulfate deionized water solution prepares dimethyl phthalate into simulated wastewater with the concentration of 5mg/L, and the treatment volume is 100 mL. An ultraviolet xenon lamp (dominant wavelength of 365nm) is used as a light source, and the illumination intensity is 120mW/cm²And applying bias voltage +0.4V (relative to a saturated calomel electrode), sampling every 1h, degrading for 8h, and performing high performance liquid chromatography on the sample. The HPLC adopts Agilent1260 HPLC. The specific degradation results are shown in fig. 3 and 4. In FIG. 3, b represents 2h- {001} TiO₂the/Ti photoelectrode ({001} crystal face exposure ratio 30%) photoelectrocatalytic degradation curve.

The test result shows that 2h- {001} TiO₂The Ti photoelectrode successfully realizes the high-efficiency photoelectrocatalysis oxidation degradation of the dimethyl phthalate simulation wastewater. DMP waste water in {001} TiO₂The removal process on the/Ti photoelectrode follows quasi-first order reaction kinetics (see b in figure 4). After 8h, 2h- {001} TiO₂The photoelectrocatalysis degradation removal rate of the/Ti photoelectrode reaches 68.7 percent.

Example 4

The 4h- {001} TiO prepared in example 1 was used₂the/Ti photoelectrode (the exposure ratio of the {001} crystal face is close to 100 percent) has high efficiencyThe DMP simulated wastewater is degraded by the following specific steps:

the photoelectric degradation DMP experiment is carried out in an electrochemical reaction tank, a sleeve cup with circulating water is additionally arranged, and the constant temperature of a reaction system is kept at 25 ℃. Adopting a three-electrode degradation system to degrade with {001} TiO₂The Ti electrode is a working electrode, the platinum sheet is a counter electrode, the distance between the working electrode and the counter electrode is 1cm, and the effective photoelectrode area is 3 multiplied by 5cm². With 0.1 mol. L^-1The sodium sulfate deionized water solution prepares dimethyl phthalate into simulated wastewater with the concentration of 5mg/L, and the treatment volume is 100 mL. An ultraviolet xenon lamp (dominant wavelength of 365nm) is used as a light source, and the illumination intensity is 120mW/cm²And applying bias voltage +0.6V (relative to a saturated calomel electrode), sampling every 1h, degrading for 8h, and performing high performance liquid chromatography on the sample. The HPLC adopts Agilent1260 HPLC. The specific degradation results are shown in fig. 3 and 4. In FIG. 3, a represents 4h- {001} TiO₂the/Ti photoelectrode ({001} crystal face exposure ratio is close to 100%) photoelectrocatalytic degradation curve.

The test result shows that 4h- {001} TiO₂The Ti photoelectrode successfully realizes the high-efficiency photoelectrocatalysis oxidation degradation of the dimethyl phthalate simulated wastewater. DMP waste water in {001} TiO₂The removal process on the/Ti photoelectrode follows quasi-first order reaction kinetics (see a in figure 4). After 8h, 4h- {001} TiO₂The photoelectric catalytic degradation removal rate of the Ti photoelectrode reaches 94.3 percent.

Example 5

A preparation method of a {001} crystal face controllable exposed titanium dioxide photoelectrode is characterized in that a titanium plate is used as a titanium source, hydrofluoric acid is used as an end capping agent, and TiO grows in situ on a titanium substrate through a hydrothermal method₂Flower-like microsphere structure, TiO₂The size is 500nm to 1 μm, the shape is a flower-like microsphere structure, and the method specifically comprises the following steps:

(1) chemically polishing a titanium plate in polishing solution obtained by mixing nitric acid, hydrofluoric acid and water, wherein the volume ratio of the nitric acid to the hydrofluoric acid to the water is 2:1:6, and removing surface grease, impurities and metal oxides;

(2) and taking out a sample, cleaning, drying, and calcining in an air atmosphere, wherein the temperature rise rate of the calcination is 1 ℃/min, the calcination temperature is 400 ℃, and the calcination time is 5 h.

The prepared titanium dioxide photoelectrode can be used for degrading organic pollutants through photoelectrocatalysis oxidation, and is prepared from {001} TiO₂The method comprises the steps of taking a/Ti electrode as an anode, taking a platinum sheet as a cathode, taking a saturated calomel electrode as a reference electrode, applying a bias voltage of +0.2 to +0.8V by adopting a three-electrode system, and carrying out photoelectrocatalysis oxidation degradation on dimethyl phthalate wastewater under the illumination condition of ultraviolet light, wherein the light intensity under the illumination condition is 50W/cm²The degradation time is 8 h.

Example 6

A preparation method of a {001} crystal face controllable exposed titanium dioxide photoelectrode is characterized in that a titanium plate is used as a titanium source, hydrofluoric acid is used as an end capping agent, and TiO grows in situ on a titanium substrate through a hydrothermal method₂Flower-like microsphere structure, TiO₂The dimension is about 500nm to 1 μm, the shape is a flower-like microsphere structure, the exposure ratio of the {001} crystal face is 20%, and the following steps are adopted:

(1) chemically polishing a titanium plate in polishing solution obtained by mixing nitric acid, hydrofluoric acid and water, wherein the volume ratio of the nitric acid to the hydrofluoric acid to the water is 4:1:6, and removing surface grease, impurities and metal oxides;

(2) putting the chemically polished smooth titanium plate into a reaction liquid obtained by mixing hydrofluoric acid and water for hydrothermal reaction, wherein the volume ratio of the hydrofluoric acid to the water is 0.007:25, the hydrothermal reaction temperature is controlled at 140 ℃, and the hydrothermal reaction time is 3 hours;

(3) and taking out a sample, cleaning, drying, and calcining in an air atmosphere, wherein the temperature rise rate of the calcination is 5 ℃/min, the calcination temperature is 550 ℃, and the calcination time is 2 h.

The prepared titanium dioxide photoelectrode can be used for degrading organic pollutants through photoelectrocatalysis oxidation, and is prepared from {001} TiO₂The method comprises the steps of taking a/Ti electrode as an anode, taking a platinum sheet as a cathode, taking a saturated calomel electrode as a reference electrode, applying a bias voltage of +0.2 to +0.8V by adopting a three-electrode system, and carrying out photoelectrocatalysis oxidation degradation on dimethyl phthalate wastewater under the illumination condition of ultraviolet light, wherein the light intensity under the illumination condition is 200W/cm²The degradation time is 3 h.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.

Claims

The preparation method of the titanium dioxide photoelectrode with the controllable exposed {001} crystal face is characterized in that a titanium plate is used as a titanium source, hydrofluoric acid is used as a blocking agent, and TiO grows in situ on a titanium substrate through a hydrothermal method₂The exposure ratio of the {001} crystal face of the obtained titanium dioxide photoelectrode can reach 100 percent by the mirror-like microsphere, and the method specifically comprises the following steps:

(1) chemically polishing a titanium plate in polishing solution obtained by mixing nitric acid, hydrofluoric acid and water;

(2) putting the chemically polished clean titanium plate into a reaction liquid obtained by mixing hydrofluoric acid and water for hydrothermal reaction; the volume ratio of the hydrofluoric acid to the water is 0.027:30, and the concentration of the hydrofluoric acid is more than or equal to 38 wt%; the hydrothermal time is 4h, and the temperature is 180 ℃;

(3) taking out a sample, cleaning, drying, and calcining in an air atmosphere; the calcination time is 2-5 h.
2. The preparation method of the titanium dioxide photoelectrode with controllable exposed {001} crystal face as claimed in claim 1, wherein the volume ratio of the nitric acid, the hydrofluoric acid and the water in the step (1) is 2:1: 6-4: 1: 6.
3. The method for preparing the titanium dioxide photoelectrode with controllable exposed {001} crystal face according to claim 1, wherein the volume ratio of the nitric acid, the hydrofluoric acid and the water in the step (1) is 3:1: 6.
4. The preparation method of the titanium dioxide photoelectrode with the controllable exposed {001} crystal face as claimed in claim 1, wherein the temperature rise rate of calcination in the step (3) is 1-5 ℃/min, the calcination temperature is 400-550 ℃, and the calcination time is 2-5 h.
The application of the {001} crystal face controllable exposed titanium dioxide photoelectrode is characterized in that the {001} crystal face controllable exposed titanium dioxide photoelectrode prepared in the method in claim 1 is used as a working electrode, a platinum sheet is used as a counter electrode, a saturated calomel electrode is used as a reference electrode, a sodium sulfate deionized water solution is used as an electrolyte in a three-electrode system, and the dimethyl phthalate wastewater is degraded by photoelectrocatalysis oxidation under ultraviolet irradiation and applied bias voltage.
6. The application of the titanium dioxide photoelectrode with controllable exposure of {001} crystal face as claimed in claim 5, wherein the intensity of ultraviolet light is 50-200 mW/cm²The bias voltage is +0.2 to +0.8V, and the light degradation time is 3 to 8 hours.