CN115814785A - TiO heterojunction with visible light response nano Au modified crystal face 2 Photoelectrode, construction and application thereof - Google Patents

TiO heterojunction with visible light response nano Au modified crystal face 2 Photoelectrode, construction and application thereof Download PDF

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CN115814785A
CN115814785A CN202211451219.4A CN202211451219A CN115814785A CN 115814785 A CN115814785 A CN 115814785A CN 202211451219 A CN202211451219 A CN 202211451219A CN 115814785 A CN115814785 A CN 115814785A
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tio
photoelectrode
crystal face
visible light
heterojunction
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CN115814785B (en
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张亚男
张盼
胡艺琼
赵国华
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Tongji University
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Abstract

The invention relates to an Au NPs modified crystal face heterojunction TiO with visible light response 2 The photoelectrode and the construction and the application thereof are characterized in that firstly, a titanium mesh is taken as a titanium source, hydrofluoric acid is taken as a crystal face end capping agent, and hydrothermal reaction is carried outIn-situ growth of TiO with anatase {001}/{101} crystal face heterojunction (A-FH) on a titanium mesh 2 Flower-like microspheres; then the mixture is carried out on TiO by a photochemical reduction method 2 Au NPs are loaded on the surface of the flower-shaped microsphere to obtain Au @ A-FH TiO 2 The Ti photoelectrode is the target product. Compared with the prior art, the invention has Au @ A-FH TiO 2 the/Ti photoelectrode has efficient and stable photoelectrocatalysis oxidation performance under visible light, 100% removal of two typical pollutants of methyl orange and bisphenol A can be realized within 60-120 min, and degradation efficiency of MO is still maintained at 81.9% after 5 times of circulation.

Description

TiO heterojunction with visible light response nano Au modified crystal face 2 Photoelectrode, construction and application thereof
Technical Field
The invention belongs to the technical field of photoelectric catalytic oxidation materials, and relates to an Au NPs modified crystal face heterojunction TiO with visible light response 2 Photoelectrode and construction and application thereof.
Background
Persistent Organic Pollutants (POPs) in the environment are a class of Pollutants that are difficult to degrade and are highly hazardous. Among them, azo dyes typified by Methyl Orange (MO) are the most commonly used dyes for textile dyeing. MO is an exotic and recalcitrant substance, and 15% to 50% of methyl orange dyes among synthetic dyes used in textile dyeing are discharged to the environment as wastewater, and these synthetic dyes cause damage to the ecosystem due to increased biological and chemical oxygen demand (BOD and COD). In addition, they affect aquatic animals by reducing the rate of photosynthesis and dissolved oxygen levels, retarding plant growth rates, interfering with and modifying the food chain, promoting toxicity, mutagenicity and carcinogenicity. Bisphenol a (BPA) is another representative persistent organic contaminant. As BPA is an important organic chemical raw material of a plurality of acid esters and resins, BPA is generally used as an antioxidant in surgical operations and an important material for curing treatment in practical application, and can be used for producing precise chemical products, such as plasticizers and the like. Due to direct discharge of low-concentration BPA in the production and manufacturing processes or disordered discharge in the use process, BPA in a water environment exceeds the standard. BPA is accumulated in the environment due to the difficult degradability of BPA and enters a human body through a biological accumulation effect, and can be used as a substitute of estrogen in the human body to interfere the signal transmission and action process which are vital to the development and the function of the body. Therefore, effective removal of methyl orange and bisphenol a contaminants from aqueous environments is an important and hot topic of water treatment in the current environmental field.
To date, research reports on methods for removing methyl orange and bisphenol A in wastewaterThere are many methods, mainly including biological, physical, chemical, and the like. However, these methods are greatly affected by environmental factors, difficult to recycle, and prone to cause secondary pollution, and thus cannot be widely applied. Therefore, a chemical oxidation method has appeared, which means that organic pollutants are degraded by chemical reaction in the presence of free radicals or substances with strong oxidizing property, and mainly comprises an ozone oxidation method, a fenton oxidation method, a photocatalytic oxidation method, an electrocatalytic oxidation method, various combined technologies and the like. Of the new oxidation technologies, photocatalysis and electrocatalysis have been proven to be an effective organic pollutant degradation technology. Photocatalysis is an advanced oxidation technology, and has the advantages of low cost, no toxicity, high efficiency and no secondary pollution. The main mechanism of action of electrocatalytic oxidation processes occurs through two different pathways, including direct oxidation and indirect oxidation: the direct oxidation is a process in which pollutants are oxidized after undergoing a direct electrochemical reaction on the surface of an anode, and firstly, organic pollutants are required to diffuse or be adsorbed to the surface of the anode, and then a direct charge transfer reaction occurs between the surface of the anode and the organic pollutants, so that the oxidation of the organic pollutants is realized. Indirect oxidation is the electrochemical generation of strongly oxidizing species (. OH,. O) at the anode 2 - Etc.) the process of oxidizing the contaminants. In recent years, the photoelectrocatalysis technology has greater potential in the field of environmental remediation and in the aspect of organic pollutant degradation, and TiO is compared with other semiconductor materials 2 The material is nontoxic and harmless, has good chemical and physical stability, is available in large amount and low in price, and becomes the photoelectrode material with the most extensive application. But at the same time TiO 2 The quantum efficiency of (A) is still low, and in addition TiO 2 The forbidden band width is 3.2eV, and the film can only absorb ultraviolet light (only 5% of the solar spectrum), but most of visible light in the solar spectrum cannot be absorbed, so that TiO 2 The photocatalytic material has a low utilization rate of sunlight.
Three-dimensional TiO with highly efficient visible light response as disclosed in CN201910804455.1 2 The photoelectrode is constructed and applied, and the preparation process of the photoelectrode is as follows: firstly, a titanium net is taken as a titanium source, so thatHydrofluoric acid is used as a blocking agent, and {001} TiO with a {001} crystal face nearly 100% exposed grows in situ on the titanium mesh through a hydrothermal reaction 2 Microspheres; loading CQDs on {001} TiO by hydrothermal treatment 2 Obtaining CQDs- {001} TiO with three-dimensional structure on the surface of the microsphere 2 the/Ti photoelectrode is the target product.
Compared with the invention, the patent has the following defects: obtained TiO 2 The microsphere only has a single {001} crystal face which is nearly 100% exposed, photogenerated carriers are gathered on the same crystal face, the recombination is easy to occur, the quantum efficiency and the charge separation efficiency are low, and the continuous operation of the photoelectrocatalysis reaction is not facilitated. TiO grown by the invention 2 The microsphere can simultaneously expose a {001} crystal face and a {101} crystal face (the exposure ratio is 1-2.
Disclosure of Invention
The invention aims to provide a TiO heterojunction with a visible light response Au NPs modified crystal face 2 The construction and the application of the photoelectrode obviously promote the separation and the transfer of photo-generated charges and effectively realize the degradation and the removal of methyl orange and bisphenol A in the water body.
The purpose of the invention can be realized by the following technical scheme:
one of the technical schemes of the invention provides Au NPs modified crystal face heterojunction TiO with visible light response 2 The method for constructing the photoelectrode comprises the steps of firstly taking a titanium net as a titanium source, taking hydrofluoric acid as a blocking agent, and growing TiO with a {001}/{101} crystal face heterojunction in situ on the titanium net through a hydrothermal reaction 2 Flower-like microspheres; then the mixture is reduced on TiO by photochemical reduction method 2 Au NPs are loaded on the surface of the flower-shaped microsphere to obtain Au @ A-FH TiO 2 The Ti photoelectrode is the target product.
Further, in the construction method of the present invention, tiO is obtained 2 The flower-like microspheres densely grow along the grid structure of the titanium mesh, the size of the flower-like microspheres is 500-1000 nm, and crystal faces of {001} and {101} are exposed together.
Further, the construction method specifically includes the steps of:
(1) Taking a titanium net, carrying out chemical polishing treatment, placing the titanium net in a mixed solution of hydrofluoric acid and water for hydrothermal reaction, cleaning an obtained product, drying and calcining the cleaned product to obtain TiO with {001}/{101} crystal face heterojunction growing in situ on the titanium net 2 Photoelectrode, noted A-FH TiO 2 /Ti；
(2) The obtained A-FH TiO 2 Putting the/Ti in a mixed solution of deionized water, methanol and an Au precursor (1% tetrachloroauric acid solution), adopting a xenon lamp as a simulated sunlight source, carrying out a photoreduction deposition process, washing and drying the obtained sample to obtain a target product Au @ A-FH TiO @ 2 a/Ti photoelectrode.
Furthermore, in the step (1), the volume ratio of hydrofluoric acid to water in the mixed solution is 21 muL: 30 mL-54 muL: 30mL. The temperature of the hydrothermal reaction is 160-200 ℃ and the time is 1-3 h; the calcination is carried out in the air atmosphere, the temperature of the calcination treatment is 400-550 ℃, and the time is 1-3 h.
Furthermore, in the step (2), the volume ratio of the deionized water to the methanol is 100mL (2-5) mL, and the volume ratio of the deionized water to the Au precursor is 100mL (35-140) muL.
Furthermore, in the step (2), when the xenon lamp is used as the simulated sunlight source, the light intensity is 400-600 mW/cm 2 The photoreduction time is 1-3 h, and the distance between the electrode and the light source is 20-30 cm.
Further, the titanium mesh after chemical polishing is taken and directly placed in H 2 O 2 Carrying out solvothermal reaction in the solution, cleaning the obtained product, drying and calcining to obtain TiO which grows in situ on the titanium mesh and does not have a specific crystal face 2 Photoelectrode, denoted A-TiO 2 /Ti, the A-TiO obtained 2 Putting the/Ti in a mixed solution of deionized water, methanol and an Au precursor (1% tetrachloroauric acid solution), adopting a xenon lamp as a simulated sunlight source, carrying out a photoreduction deposition process, washing and drying the obtained sample to obtain a contrast electrode Au @ A-TiO 2 /Ti。
The second technical scheme of the invention provides an Au NPs modified crystal face heterojunction with visible light responseTiO 2 And the photoelectrode is prepared by the preparation method.
Further, the photoelectrode is used for degrading and removing methyl orange and bisphenol A pollutants in a water body.
Further, with Au @ A-FH TiO 2 The method comprises the following steps of constructing a three-electrode system by taking a/Ti photoelectrode as a working electrode, a platinum sheet as a counter electrode and a saturated calomel electrode as a reference electrode, applying bias voltage by taking a sodium sulfate solution as an electrolyte solution under the irradiation of a xenon lamp, and carrying out photoelectrocatalysis oxidation degradation on methyl orange and bisphenol A pollutant solutions.
Furthermore, when the methyl orange pollutants are degraded, the wavelength range of the xenon lamp light source is limited to 420-800 nm by using the optical filter, and the light intensity is 400-600 mW/cm 2 The applied bias voltage is + 0.2- +1.0V, and the light degradation time is 1-2 h.
According to the invention, researches show that the essence of the photoelectrocatalysis reaction is an interface reaction, and pollutants are diffused and adsorbed on the surface of the catalyst and simultaneously undergo photoelectrocatalysis oxidation reaction, so that the light absorption efficiency, the charge separation efficiency and the interface injection efficiency of the catalyst greatly influence the degree of the photoelectrocatalysis oxidation reaction. Therefore, an efficient photoelectrocatalysis interface needs to be constructed, and efficient degradation and removal of pollutant molecules are realized from the aspects of enhancing the light absorption efficiency, the charge separation efficiency and the interface injection efficiency of the photoelectrocatalysis interface.
Based on the method, the invention adopts a titanium mesh material as a substrate, and the co-exposed TiO crystal planes of the {001} crystal face and the {101} crystal face are grown in situ 2 Flower-like microspheres further reduced on TiO by photochemical reduction 2 Loading Au NPs on the surface to obtain Au @ A-FH TiO 2 A Ti photoelectrode material. The three-dimensional reticular titanium substrate can be folded and cut at will, and is suitable for the requirements of different reactors in practical application; due to the plasma effect of the Au nanoparticles on the surface, the absorption spectrum range is widened to 550nm, and the light absorption efficiency of the photoelectrode is effectively improved; in addition, au and TiO 2 The formed Schottky junction and the crystal face heterojunction formed by co-exposing the {001} and {101} crystal faces cooperate to promote the rapid separation of photo-generated electrons and holes. This Au @ A-FH TiO 2 the/Ti photoelectric anode has efficient photoelectric catalytic oxidation performance under visible light (the photoelectric current density reaches up to 1.18 x 10) -5 A/cm 2 The service life of excited electrons is 4.21-4.50 ns), the highest removal rate of methyl orange and bisphenol A can reach 97.9% within 60min, and the photoelectrode has high stability, and the degradation efficiency of MO is still maintained at 81.9% after 5 cycles. The photoelectrode material and the technology are suitable for the field of photoelectrocatalysis degradation of methyl orange and bisphenol A environmental pollutants in wastewater.
In the construction process of the photoelectrode, the invention limits the raw material addition amount (such as hydrofluoric acid, au precursor solution and the like), the reaction temperature and the reaction time of each reaction process. First, in A-FH TiO 2 In the preparation process of the Ti photoelectrode, hydrofluoric acid is a crystal face capping agent, so that the concentration, hydrothermal reaction time and temperature of the hydrofluoric acid are limited. The invention relates to in-situ growth of TiO on a titanium mesh 2 The flower-shaped microspheres have low exposure areas of {001} crystal faces and {101} crystal faces when the concentration of hydrofluoric acid is too low; when the concentration of hydrofluoric acid is too high, the {001} crystal face is excessively etched, so that a crystal face heterojunction cannot be formed, and meanwhile, the titanium mesh substrate is also corroded and broken, so that an electrode is damaged, and a photoelectrocatalysis reaction cannot be carried out. The hydrothermal time is too short, the temperature is too low, and the exposure proportion of the {101} surface is larger; the water heating time is too long, the temperature is too high, and the exposure proportion of the 001 surface is larger. Therefore, in the experimental process, when the volume ratio of hydrofluoric acid to water is 21 mu L:30 mL-54 mu L:30mL, and the hydrothermal time and temperature respectively satisfy 1-3 h and 160-200 ℃, the A-FH TiO with the optimal {001}/{101} crystal face exposure ratio can be obtained 2 a/Ti photoelectrode. Secondly, au nano-particles are prepared by a photo-reduction method and loaded on A-FH TiO 2 The addition amount of the Au precursor solution, the time for depositing Au by photoreduction and the intensity of a light source are limited on the Ti surface: 1) The addition amount of the Au precursor solution can affect the size and the loading capacity of the Au nanoparticles, and when the addition amount is too low, the loading capacity of the Au nanoparticles is low, so that the absorption efficiency of visible light is affected; when the addition amount is too high, the size of the Au nano-particles is large, and TiO is shielded in a large area 2 The active crystal face influences the interface activity and limits the lightThe electrocatalytic oxidation degradation efficiency is optimized by the addition amount of the Au precursor solution, and the optimal 35-140 mu L is determined; 2) The time for depositing Au nanoparticles by photoreduction is too short, the loading capacity of the Au nanoparticles is low, and the Au nanoparticles are dispersed unevenly, so that the light absorption efficiency of the photoelectrode is influenced; the photoreduction time is too long, the Au nanoparticles are agglomerated, crystal faces of {001} and {101} are shielded, the surface plasma effect is reduced, the photoelectrocatalysis performance is reduced, and the photoreduction time is optimized to determine 1-3 h as the optimal time; 3) The light intensity in the photoreduction process is too low, au 3+ Is reduced to Au 0 The conversion of (3) is reduced; the photoreduction time is prolonged on the premise of meeting the optimal Au loading capacity, and the experiment cost is increased. The illumination intensity of the Au nanoparticles deposited by photoreduction is too high, the Au nanoparticles are easy to agglomerate in a large amount in a short time, the Au nanoparticles are not uniformly dispersed and shield the photoelectrode, and the illumination intensity is optimized to determine 400-600 mW/cm 2 For optimum light intensity.
Compared with the prior art, the invention has the following advantages:
(1) Au @ A-FH TiO prepared by the invention 2 Ti photoelectrode, tiO grown in situ on a titanium mesh by hydrothermal method 2 The flower-shaped microsphere has a co-exposed crystal face of {001} and {101} and can form a heterojunction of {001}/{101} crystal face; and further loading Au nano particles on the surface of the electrode by a simple photoreduction method, wherein the size of the Au nano particles is 10-30 nm, and the Au nano particles can be uniformly dispersed on the surfaces of the crystal planes of {001} and {101 }.
(2)Au@A-FH TiO 2 The absorption spectrum range of the Ti is widened to 550nm due to the plasma effect of the Au nanoparticles on the surface, and the Ti has high-efficiency light absorption efficiency. Au nano particles on the photoelectrode generate hot electrons under visible light and transfer the hot electrons to TiO 2 Using Au/TiO 2 The Schottky junction promotes the rapid separation of photo-generated electrons and holes, and meanwhile, the TiO 2 The {001}/{101} crystal face heterojunction on the surface promotes electrons to gather to a {101} face and further transfer to a counter electrode through a titanium mesh substrate, and efficient charge separation efficiency is achieved. Compared with common TiO 2 And has high-efficiency photoelectrocatalysis performance.
(3) Prepared by the inventionAu@A-FH TiO 2 the/Ti photoelectrode has higher stability and cyclicity. The titanium mesh substrate with the three-dimensional mesh structure is beneficial to contact and adsorption of pollutants and the catalyst. The titanium mesh is easy to cut, fold and the like, so that the size and the shape of the electrode can be adjusted according to the requirements of environmental devices, and the titanium mesh has a good practical application prospect. In addition, the photoelectrode is constructed to solve the problem that the powder photocatalyst is difficult to recycle, and the degradation efficiency of MO of the photoelectrode is still maintained at 81.9 percent after 5 times of circulation. Therefore, the nano Au modified A-FH TiO with visible light response constructed by the invention 2 the/Ti photoelectrode has high-efficiency light absorption efficiency and charge separation efficiency, and can realize high-efficiency photoelectrocatalysis oxidation removal of typical pollutants methyl orange and bisphenol A in a water environment.
Drawings
FIG. 1 shows 2% of Au @ A-FH TiO prepared in example 2 2 (iii) scanning electron and transmission electron micrographs of/Ti;
FIG. 2 shows 2% of Au @ A-TiO prepared in examples 1 and 2 2 [ Ti-electro and 2% ]Au @ A-FH TiO 2 A plot of linear voltammetric scan versus Ti-photo;
FIG. 3 shows 2% of Au @ A-TiO prepared in examples 1 and 2 2 /Ti、A-FH TiO 2 Ti and 2% of Au @ A-FH TiO 2 Comparison graph of photoelectric properties of/Ti;
FIG. 4 shows 2% of Au @ A-TiO prepared in examples 1 and 2 2 /Ti、A-FH TiO 2 Ti and 2% of Au @ A-FH TiO 2 A UV-visible diffuse reflectance and light absorption efficiency spectrum of Ti;
FIG. 5 is Au @ A-FH TiO prepared in example 2 2 A process chart of degrading methyl orange and bisphenol A by a Ti photoelectrode is shown, wherein a graph of the ratio of the concentrations of the methyl orange and the bisphenol A to the initial concentration and the time is shown in a figure 5a, and a graph of the kinetics is shown in a figure 5 b.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.
In the following examples, unless otherwise specified, raw materials or processing techniques are all conventional and commercially available products or conventional processing techniques in the art.
Example 1:
TiO with {001}/{101} crystal face heterojunction 2 The preparation method of the photoelectrode specifically comprises the following steps:
folding metal Ti net into two layers, cutting into 3.5 × 5.0cm, and polishing with chemical polishing solution (volume ratio: HNO) 3 :HF:H 2 O = 20ml. Adding 30mL of deionized water and 27 mu L of hydrofluoric acid (more than or equal to 38 wt%) into 100mL of polytetrafluoroethylene substrate, uniformly mixing, putting the dried metal titanium mesh subjected to chemical polishing into the polytetrafluoroethylene substrate, putting the polytetrafluoroethylene substrate into a high-pressure reaction kettle, carrying out hydrothermal treatment for 3 hours at 180 ℃, cooling to room temperature after the reaction is finished, washing the surface with the deionized water, and naturally drying. Calcining at 450 ℃ for 3h in air atmosphere at the heating rate of 3 ℃/min to obtain a crystal face exposure ratio of 2: 1A-FH TiO 2 a/Ti photoelectrode.
Similarly, the polished titanium mesh was placed on a 100mL polytetrafluoroethylene substrate, to which was added 100mL H 2 O 2 And (3) heating the solution in a solvent at 100 ℃ for 1h, cooling to room temperature after the reaction is finished, washing the surface with deionized water, and naturally drying. Calcining at 450 ℃ for 3h under the air atmosphere with the heating rate of 3 ℃/min to obtain the A-TiO without specific crystal face 2 the/Ti photoelectrode was used as a comparative photoelectrode 1.
Example 2:
au NPs modified crystal face heterojunction TiO with visible light response 2 The preparation method of the photoelectrode specifically comprises the following steps:
the A-TiO obtained in example 1 was added 2 /Ti、A-FH TiO 2 (iii) Ti photoelectrode material, {001} -A-TiO 2 The Ti photoelectrode is put into a mixed solution consisting of 100ml deionized water, 5ml methanol and 70 mu L Au precursor solution (1 percent tetrachloroauric acid solution), and (under the irradiation of a xenon lamp)The light source intensity is 500mW/cm 2 Lamp head to electrode distance d =25 cm) was continuously stirred for 1h to complete the photoreduction deposition process. Washing the sample with deionized water, and drying in a vacuum oven at 60 deg.C for 3h to obtain a comparative electrode 2 @ -TiO 2 2% of/Ti and target product Au @ A-FH TiO 2 a/Ti photoelectrode.
In addition, the reference exposure ratio was 2: 1A-FH TiO 2 The preparation process of the/Ti photoelectrode comprises the following steps of adjusting the Au NPs loading method: by using A-FH TiO 2 The working electrode was made of/Ti, and the electrolyte solution was made of 0.1M NaCl and 2.5mM HAuCl 4 And (4) forming. The potential was stepped to-0.6V vs. SCE for 5s and then returned to-0.2V for 5s. At this time, 2% of Au @ A-TiO was obtained 2 a/Ti-electro photoelectrode as comparative photoelectrode 2.
The morphology of the target electrode is characterized by adopting a field emission scanning electron microscope technology (Hitachi S-4800), and is shown in figure 1, and figure 1 shows that TiO is used for characterization 2 The shape of the microsphere is flower-shaped, the size of the microsphere is between 500 and 1000nm, the microsphere is uniformly distributed on a titanium mesh framework to form a three-dimensional network structure, and the obtained Au nanoparticles are uniformly distributed on TiO 2 And {001} and {101} crystal planes.
Example 3 to example 4:
compared to example 2, most of them are the same except that in this example: the gas-phase hydrothermal reaction time is 1h and 2h respectively, and the exposure ratio of the {001} crystal face to the {101} crystal face is 1:1 and 1.5: 1A-FH TiO 2 a/Ti photoelectrode.
As is clear from the combination of example 1 and examples 3 to 4, the exposure ratios of the {001} and {101} crystal planes are related to the amount of HF capping agent used and the hydrothermal time, and in the present invention, when the hydrothermal time is 1h, 2h and 3h, the exposure ratios of the {001} crystal plane and the {101} crystal plane are 1: 1. 1.5:1 and 2:1, the {001} crystal face and the {101} crystal face are exposed together to form a crystal face heterojunction, so that photo-generated holes are gathered on the {001} crystal face, photo-generated electrons are quickly transferred to the {101} crystal face and finally reach a counter electrode through a titanium mesh substrate, and efficient separation of electrons and holes is realized. The hydrothermal time was adjusted to 4 hours, and 100% of the exposed {001} crystal plane was obtained, and only a single crystal plane existed, and a plane heterojunction could not be formed.
Example 5 to example 6:
compared to example 2, most of them are the same except that in this example: the volume of the Au precursor solution was adjusted to 35. Mu.L and 140. Mu.L, and the electrode obtained by photoreduction deposition was labeled 1% 2 Ti and 4% of Au @ A-FH TiO 2 /Ti。
Example 7:
the A-FH TiO prepared in example 1 was used 2 2% of Ti and prepared in example 2 Au @ A-FH TiO 2 The Ti photoelectrode is used for carrying out the research on the photoelectrocatalysis oxidation performance,
the method comprises the following specific steps:
the photoelectrocatalysis performance test is carried out in a square quartz reaction tank, the electrolyte solution is 0.1mol/L sodium sulfate solution, a three-electrode system is adopted, and the content is respectively 2 percent 2 /Ti-electro、2％Au@A-TiO 2 /Ti、A-FH TiO 2 Ti and 2% Au @ A-FH TiO 2 (Ti) as working electrode, platinum sheet as counter electrode, saturated calomel electrode as reference electrode, chenghua CHI660C electrochemical workstation for testing linear sweep voltammetry curve, mott-Schottky curve, i-t curve and AC impedance spectrum to obtain a visible light filter (A) with AM 1.5G>420 nm) as a light source, the distance between the light source and the working electrode being 1cm. The test results are shown in FIGS. 2 and 3, and the results indicate that 2% was achieved by Au @ A-FH TiO under light conditions 2 The photoresponsive performance of the/Ti (-photo) photoelectrode is obviously better than 2 percent 2 /Ti-electro、2％Au@A-TiO 2 Ti and A-FH TiO 2 The photocurrent density can reach 1.18 to 10 per Ti -5 A/cm 2 Respectively 2% of Au @ A-TiO 2 Ti and A-FH TiO 2 5.9 times and 1.97 times of/Ti, the impedance value was about 5000. Omega. In comparison with 2% of Au @ A-TiO 2 Ti and A-FH TiO 2 A reduction of about 4.8 and 2.4 times in/Ti, calculated carrier concentration of 2.67X 10 20 cm -3 Compared with 2% of Au @ A-TiO 2 Ti and A-FH TiO 2 The Ti is respectively improved by 7.9 times and 2.0 times.
As is clear from the comparison, the present invention has a {001}/{101} crystal plane heterojunctionTiO 2 Au NPs are modified on the surface of the nano microsphere, hot electrons generated by the Au NPs under visible light are transferred to a {001} crystal face through a metal-semiconductor Schottky junction, then quickly reach the {101} crystal face through a {001}/{101} crystal face heterojunction and finally reach a counter electrode through a titanium mesh substrate, and the hot electron-hole separation efficiency of Au under visible light is improved, so that target pollutants are efficiently removed, and the action effect and mechanism of the 'double junction' are unavailable for a common photoelectrode material without the crystal face heterojunction.
Example 8:
compared to example 7, most of them are the same except that in this example: change of working electrode to 1% 2 and/Ti, performing a photoelectrocatalysis performance test. Test results show that the electrode has better light response performance under the illumination condition, and the photocurrent density can reach 0.75 to 10 -5 A/cm 2 Impedance of about 11000 omega, and carrier concentration of 1.58X 10 20 cm -3 。
Example 9:
compared to example 7, most of them are the same except that in this example: change the working electrode to 4% Au @ A-FH TiO 2 and/Ti, performing a photoelectric catalytic performance test. The test result shows that the electrode has better light response performance under the illumination condition, and the photocurrent density can reach 0.90 x 10 -5 A/cm 2 Impedance of about 6000 Ω and carrier concentration of 2.43 × 10 20 cm -3 。
Example 10:
the A-FH TiO prepared in example 1 was used 2 /Ti with Au @ A-TiO prepared in example 2 2 Ti and Au @ A-FH TiO 2 the/Ti photoelectrode is subjected to an ultraviolet-visible diffuse reflection test, shown in figure 4a, and A-TiO without specific crystal face 2 In comparison with Ti, A-FH TiO 2 The light absorption intensity of the whole Ti/TiO is improved, the light absorption range of the Au nano-particles is expanded to 550nm after the Au nano-particles are further loaded, and fig. 4b shows that the construction of {001}/{101} crystal face heterojunction and the loading of the Au nano-particles obviously promote TiO (titanium oxide) crystal face heterojunction 2 Light absorption efficiency η of abs 。
Example 11:
the A-FH TiO prepared in example 1 was used 2 [ solution ] Ti and Au @ A-FH TiO prepared in example 2 2 The Ti photoelectrode is used for degrading methyl orange pollutants and comprises the following specific implementation steps:
the experiment of photoelectrocatalysis degradation of methyl orange is carried out in a cuboid quartz degradation pool with the volume of 50ml, a three-electrode degradation system is adopted, and Au @ A-FH TiO 2 The Ti photoelectrode is a working electrode, the platinum sheet is a counter electrode, the saturated calomel electrode is a reference electrode, the distance between the working electrode and the counter electrode is 10cm, and the effective photoelectrode area is 3.5 multiplied by 4.5cm 2 . Methyl orange simulated wastewater with the concentration of 2mg/L is prepared by 0.1mol/L sodium sulfate solution, and the volume is 45mL. The wavelength range of a xenon lamp light source is limited between 420 and 800nm by adopting a visible light filter, and the illumination intensity is 520mW/cm 2 The degradation experiment was performed with a bias of +0.4V (relative to a saturated calomel electrode) and the degraded sample was analyzed by a UV-1800 UV spectrometer. The specific degradation results are shown in fig. 5. In FIG. 5, a represents Au @ A-FH TiO 2 The curve of the simulated wastewater containing methyl orange in the photoelectrocatalysis degradation by the Ti photoelectrode, and b represents a first-order kinetic curve corresponding to the photoelectrocatalysis degradation process.
FIG. 5a test results show that Au @ A-FH TiO 2 The Ti photoelectrode successfully realizes the efficient photoelectrocatalysis oxidation degradation of the simulation waste water containing the methyl orange. After 1h of degradation, au @ A-FH TiO 2 The photoelectrocatalysis degradation removal rate of the/Ti photoelectrode to methyl orange within 60min reaches 97.9 percent, which shows that Au @ A-FH TiO 2 The Ti photoelectrode realizes the efficient removal of methyl orange pollutants in water. FIG. 5b shows methyl orange in A-FH TiO 2 Ti and Au @ A-FH TiO 2 The removal process on the/Ti photoelectrode conforms to the quasi-first order reaction kinetics.
Example 12 to example 13:
compared to example 10, most of them are the same except that in this example: the concentration of methyl orange was adjusted to 1mg/L and 3mg/L, and a photocatalytic oxidation degradation experiment was performed.
The A-FH TiO prepared in example 1 was used 2 [ solution ] Ti and Au @ A-FH TiO prepared in example 2 2 Ti photoelectrode for degrading bisphenol A pollutantsThe method comprises the following steps:
example 14
The A-FH TiO prepared in example 1 was used 2 [ solution ] Ti and Au @ A-FH TiO prepared in example 2 2 the/Ti photoelectrode degrades bisphenol a contaminants, and the implementation procedure is largely the same as in example 11, except that in this example: the concentration of bisphenol A is 1mg/L, and Agilent 1260 high performance liquid chromatography test is carried out on the degraded sample.
FIG. 5a test results show that Au @ A-FH TiO 2 The Ti photoelectrode successfully realizes the efficient photoelectrocatalysis oxidation degradation of the bisphenol A-containing wastewater. After 1h of degradation, au @ A-FH TiO 2 The photoelectrocatalysis degradation removal rate of the/Ti photoelectrode to the bisphenol A within 60min reaches 97.3 percent, which shows that Au @ A-FH TiO 2 The Ti photoelectrode realizes the high-efficiency removal of bisphenol A pollutants in water. FIG. 5b shows that bisphenol A simulated wastewater is treated in A-FH TiO 2 Ti and Au @ A-FH TiO 2 The removal process on the/Ti photoelectrode conforms to the quasi-first order reaction kinetics.
In addition, as can be seen from the above-mentioned example 14, the applied electric field in the conventional Au electrodeposition process is applied to TiO 2 The surface performance has certain influence, the invention adopts the light reduction to deposit Au, only needs light assistance without external voltage, has simple and convenient operation and lower experimental cost, and simultaneously, the electrode after the light reduction modification of Au shows higher photoresponse and photoelectrocatalysis oxidation capability through photoelectrochemical performance test and pollutant degradation experiment, which shows that the light reduction deposition method can effectively improve A-FH TiO 2 The photoelectric property of Ti, thereby realizing the high-efficiency removal of pollutants.
Example 15 to example 16:
compared to example 14, most of them are the same except that in this example: the concentration of bisphenol A was adjusted to 0.5mg/L and 2mg/L, and a photocatalytic oxidation degradation experiment was performed.
The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make modifications and alterations without departing from the scope of the present invention.

Claims (8)

1. Au NPs modified crystal face heterojunction TiO with visible light response 2 The method for constructing the photoelectrode is characterized in that a titanium mesh is taken as a titanium source, hydrofluoric acid is taken as a crystal face end capping agent, and TiO with anatase {001}/{101} crystal face heterojunction A-FH is grown in situ on the titanium mesh through a hydrothermal reaction 2 Flower-like microspheres; then the mixture is carried out on TiO by a photochemical reduction method 2 Au NPs are loaded on the surface of the flower-shaped microsphere to obtain Au @ A-FH TiO 2 The Ti photoelectrode is the target product.
2. The Au NPs modified crystal face heterojunction TiO of claim 1 with visible light response 2 The method for constructing the photoelectrode is characterized by comprising the following steps:
(1) Taking a titanium net, carrying out chemical polishing treatment, and then placing the titanium net in a mixed solution of hydrofluoric acid and water, wherein the volume ratio V of the hydrofluoric acid to the water HF ：V H2O 30 mL-54 μ L of water, 30mL, performing hydrothermal reaction at 160-200 ℃ for 1-3 h; the obtained product is calcined in the air atmosphere after being cleaned, the treatment temperature is 400-550 ℃, the treatment time is 1-3 h, and TiO with anatase {001}/{101} crystal face heterojunction A-FH grown in situ on a titanium network is obtained 2 Photoelectrode, noted A-FH TiO 2 /Ti；
(2) The obtained A-FH TiO 2 Putting the Au precursor into a mixed solution of deionized water, methanol and the Au precursor, wherein the Au precursor is a 1wt% tetrachloroauric acid solution, adopting a xenon lamp as a simulated sunlight source, carrying out a photoreduction deposition process for a certain time, and washing and drying the obtained sample to obtain a target product Au @ A-FH TiO @ 2 a/Ti photoelectrode.
3. A display device as claimed in claim 2Photoresponse Au NPs modified crystal face heterojunction TiO 2 The construction method of the photoelectrode is characterized in that in the step (2), the volume ratio of deionized water to methanol is 100mL (2-5 mL), and the volume ratio of deionized water to Au precursor is 100mL (35-140 muL).
4. The Au NPs modified crystal face heterojunction TiO of claim 2 with visible light response 2 The method for constructing a photoelectrode is characterized in that in the step (2), the intensity of the light source is 400-600 mW/cm 2 The photoreduction time is 1-3 h, and the distance between the electrode and the light source is 20-30 cm.
5. Au NPs modified crystal face heterojunction TiO with visible light response 2 A photoelectrode produced by the construction method according to any one of claims 1 to 4.
6. The Au NPs modified crystal face heterojunction TiO of claim 5 with visible light response 2 The application of the photoelectrode is characterized in that the photoelectrode is used for degrading and removing methyl orange and bisphenol A pollutants in a water body.
7. The Au NPs modified crystal face heterojunction TiO of claim 6 with visible light response 2 The photoelectrode is characterized by being prepared from Au @ A-FH TiO 2 The method comprises the following steps of constructing a three-electrode system by taking a/Ti photoelectrode as a working electrode, a platinum sheet as a counter electrode and a saturated calomel electrode as a reference electrode, applying bias voltage by taking a sodium sulfate solution as an electrolyte solution under the irradiation of a xenon lamp, and degrading methyl orange and bisphenol A pollutant solutions by photoelectrocatalysis oxidation.
8. The Au NPs modified crystal face heterojunction TiO of claim 7 with visible light response 2 The application of the photoelectrode is characterized in that the concentration of a sodium sulfate solution is 0.1mol/L, the concentration of a methyl orange and bisphenol A pollutant solution is 0.5-3 mg/L, a light filter is used for limiting the wavelength range of a xenon lamp light source to be 420-800 nm, and the light intensity is 400-600 mW/cm 2 The applied bias voltage is + 0.2- +1.0V, and the photoelectric degradation time is 1-4 h.
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