A dual-photoelectrode photoelectrochemical cell for light-driven degradation of organic pollutants and simultaneous electrical energy release

Abstract

The present invention discloses a dual-photoelectrode photoelectrochemical cell that can degrade organic pollutants by light and release electrical energy simultaneously, belonging to the technical field of solar photoelectric conversion and environmental pollutant treatment. The photoelectrochemical cell structure includes a TiO2 / ZnO photoanode, a CuO x The cell consists of a photoelectrochemical cell (PFC) and a pTTh photocathode, along with an electrolyte solution containing organic pollutants. Under illumination, the photoanode and photocathode are excited to generate active electrons and holes. These holes directly oxidize the organic pollutants, or electrons / holes drive a solution reaction to produce oxygen-containing active free radicals, indirectly oxidizing them. This degrades the pollutants and simultaneously releases electrical energy. This photoelectrochemical cell, devoid of precious metals, membranes, or enzymes, relies solely on solar energy to drive a semiconductor catalyst to simultaneously degrade pollutants and release electrical energy. It offers significant advantages, including low cost, environmental friendliness, safety, and ease of large-scale implementation.

Description

Technical Field

[0001] The present invention relates to the technical field of solar photoelectric conversion and environmental pollutant treatment, and in particular to a dual-photoelectrode photoelectrochemical cell that light-drives the degradation of organic pollutants and simultaneously releases electrical energy. Background Art

[0002] 87% of global energy demand comes from non-renewable resources such as fossil fuels, coal, oil, and natural gas. If this trend continues, the Earth's proven non-renewable resources will be depleted. At the same time, the relentless exploitation and use of non-renewable resources has led to increasingly severe environmental pollution. In this context, the development of pollution-free, green, renewable energy sources has become a crucial research topic to ensure energy and environmental security and maintain steady global economic development. As a clean, abundant, and renewable resource, the efficient development and utilization of solar energy is one of the ideal solutions to address energy shortages and environmental challenges. The simultaneous generation of electricity through the photocatalytic degradation of organic pollutants in a photoelectrochemical cell is a highly attractive process because it offers dual environmental benefits: pollutants are degraded while solar energy is converted into useful energy sources such as electricity and hydrogen. In the presence of oxygen, no hydrogen is detected in the photoelectrochemical cell; electrons transferred to the cathode reduce oxygen, generating electricity for the photoelectrochemical cell. For example, dual-photoelectrode photoelectrochemical cells such as WO3 / W or TiO2 / Ti photoanode and Cu2O / Cu photocathode [Environmental Science & Technology, 2012, 46(20): 11451; Journal of hazardous materials, 2013, 262, 304], WO3 / W photoanode and Pt / PVC (Pt-modified crystalline silicon photovoltaic cell) photocathode [Chemical Engineering Journal, 2014, 252, 89], can generate electricity and purify wastewater by using organic matter in wastewater as substrates. However, the discharge capacity of these systems is very limited. The open circuit voltage of the dual-photoelectrode photoelectrochemical cell constructed with WO3 / W photoanode and Pt / PVC photocathode under illumination is 0.38 V and the short circuit current is 0.35 mA cm –2 , with a maximum power of 133 μW cm –2 Although the dual photoelectrode fuel cell constructed with BiVO4 / WO3 / W as the photoanode and Pt / BJS (Pt-modified commercial single-junction silicon) as the photocathode obtained an open circuit voltage of 0.82 V and a current of 0.43 mA cm –2However, the Pt / BJS photocathode of this system contains precious metal catalysts and is driven by silicon cells, which are relatively expensive [Applied Catalysis B: Environmental, 2016, 183, 224]. In addition, a dual-photoelectrode photoelectrochemical cell constructed with a photoanode such as TiONTs / Ti, CdS / FTO, or CdSe / FTO and a photocathode such as Cu2O / Cu has a maximum open circuit voltage of 0.62 V and a short circuit current of only 0.31 mA cm –2 , with a maximum power of 60 μW cm –2 [Journal of Materials Chemistry A, 2015, 3, 3416-3424]. In summary, although dual-photoelectrode photoelectrochemical cell systems have received some attention in recent years, their power generation and organic pollutant degradation performance need to be improved. Furthermore, existing research on photocathodes mostly uses Cu2O / Cu electrodes or Pt-modified Si cells, which suffer from poor stability and high prices. The selection of photocathode / anode materials still requires considerable exploration, and the generated electricity also requires further development and utilization. Summary of the Invention

[0003] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a dual-photoelectrode photoelectrochemical cell that can degrade organic pollutants by light and release electrical energy at the same time, specifically providing a TiO2 / ZnO photoanode and a CuO x The invention relates to a preparation method for a light-driven dual-photoelectrode photoelectrochemical cell device constructed with a pTTh photocathode and its dual-functional application in producing green electricity and degrading organic pollutants. The dual-photoelectrode photoelectrochemical cell is free of precious metals, diaphragms, and enzymes and relies solely on solar energy to drive semiconductor catalysts to simultaneously achieve green electricity production and organic pollutant degradation. The open circuit voltage of a single cell is 1.0 V and the short-circuit current density is 1.5 mA / cm 2 , the maximum discharge power density can reach 0.38mW / cm 2 ; Degradation of 10 mg / mL Rhodamine B took about 2 hours. In the process of 5 consecutive degradations of 10 mg / mL Rhodamine B, the degradation and decolorization rate of Rhodamine B could reach more than 95% for 5 consecutive times. The discharge power of the photoelectrochemical cell was maintained at 0.35-0.4 mW / cm 2 , and has the significant advantages of being cheap, green, safe, and easy to implement on a large scale.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for light-driven dual-photoelectrode photoelectrochemical cell to degrade organic pollutants while releasing electrical energy, using TiO2 / ZnO as the photoanode and CuO x / pTTh as photocathode, TiO2 / ZnO photoanode, CuO x The / pTTh photocathode is placed in an electrolyte solution containing organic pollutants, and the external circuit is connected to the electrical devices through wires to form a closed loop. Under light conditions, it degrades organic pollutants and produces green electricity.

[0006] Under light conditions, the cell's photoanode and photocathode are excited to generate active electrons and holes. These holes directly oxidize organic pollutants, or electrons / holes drive a solution reaction to produce oxygen-containing active free radicals, indirectly oxidizing them, thereby degrading them. Electricity is generated through the Fermi energy difference between the photoanode and photocathode, and the photoelectrochemical reaction of the solution couple. Once the organic pollutants in the electrolyte solution are completely degraded, the cell, under light conditions, undergoes a water oxidation reaction on the photoanode surface and an oxygen reduction reaction on the photocathode surface, allowing for long-term, stable discharge.

[0007] The organic pollutants include dyes, pesticides, and pharmaceuticals. Dyes include rhodamine B, methyl blue, and methyl orange; pesticides include organophosphorus pesticides, organochlorine pesticides, and organonitrogen pesticides; and pharmaceuticals include parachlorophenol, tetracyclines, and penicillins. The concentration of the organic pollutants is preferably 10 mg / mL or greater.

[0008] The conductive wire is a sheet, foil, mesh, wire, or the like of a metal such as Cu, Ni, or Ti.

[0009] The present invention uses TiO2 / ZnO as the photoanode, CuO x / pTTh is the photocathode. The TiO2 / ZnO photoanode comprises a TiO2 nanorod film synthesized on a conductive substrate and a ZnO layer deposited on the TiO2 nanorod film, and the conductive substrate is fluorine-doped tin oxide (FTO) conductive glass. The TiO2 film is a TiO2 nanorod vertically arranged in an array on a conductive substrate, and the ZnO film is composed of dense ZnO nanoparticles. The TiO2 / ZnO photoanode is beneficial for shortening the transfer path of photogenerated electrons, inhibiting the recombination of photogenerated electrons and holes, and has higher photocatalytic activity. The CuO x / pTTh photocathode comprises CuO deposited on a conductive substrate x Thin films and deposited on CuO x The flower-shaped pTTh film on the conductive substrate is carbon paper. x The film is composed of dense CuO x The pTTh film is composed of three-dimensional pTTh flowers.

[0010] Furthermore, the preparation method of the TiO2 / ZnO photoanode comprises the following steps:

[0011] 1) mixing a titanium source and an acid solution, transferring the resulting mixed solution into an autoclave containing a conductive substrate, heating, and annealing after the reaction to obtain a TiO2 thin film; and / or;

[0012] 2) using an aqueous solution of zinc acetate dihydrate and zinc nitrate hexahydrate as an electrolyte, a TiO2 film as a working electrode, a platinum sheet as a counter electrode, and a saturated calomel as a reference electrode to electrodeposit a ZnO film, followed by annealing to obtain a TiO2 / ZnO photoanode; and / or;

[0013] The CuO x The preparation method of the pTTh photocathode comprises the following steps:

[0014] 3) Using a conductive substrate, platinum sheet and saturated calomel as working electrode, counter electrode and reference electrode respectively, pulse electrodeposition was carried out in an electrolyte consisting of copper nitrate and lactic acid to obtain CuO x Film; and / or;

[0015] 4) CuO x The film was used as the working electrode, platinum sheet as the counter electrode, saturated calomel electrode as the reference electrode, terthiophene and LiClO4 acetonitrile solution as the electrolyte, and the CuO film was deposited on the CuO film by cyclic voltammetry electrochemical deposition method. x Thin film deposition to obtain CuO x / pTTh photocathode.

[0016] Furthermore, in the above-mentioned TiO2 / ZnO photoanode preparation process, the titanium source is selected from tetrabutyl titanate, with a volume ratio of 1% to 10% to the acid solution; the acid solution is selected from hydrochloric acid with a concentration of 4 to 8 mol / L; the heating temperature is 150 to 200°C, and the time is 60 to 600 minutes; more specifically, the heating temperature is 160 to 180°C, and the time is 80 to 100 minutes. The annealing temperature is 300 to 600°C, and the time is 1 to 10 hours. The TiO2 film prepared in this step is a vertically arranged array of TiO2 nanorods.

[0017] A ZnO thin film is electrochemically deposited on the surface of a TiO2 thin film. During the electrochemical deposition process, the electrolyte is an aqueous solution of 1-25 mmol / L zinc acetate dihydrate and 1-25 mmol / L zinc nitrate hexahydrate. The voltage of the electrochemical deposition is -1.5 to -1 V, and the deposition time is 150 to 350 seconds. The annealing temperature is 400 to 500°C, and the time is 1 to 5 hours. The ZnO thin film is composed of dense ZnO nanoparticles, which are composited on the surface of the TiO2 thin film, thereby forming a TiO2 / ZnO photoelectrode.

[0018] In CuO xDuring the preparation of the pTTh photocathode, the CuO x The electrolyte is specifically composed of 0.1-0.2 mol / L Cu(NO3)2 and 1.8-2.5 mol / L lactic acid. The pulse electrodeposition is performed at -60-30 mA cm -2 Deposition is carried out for 1 to 5 seconds, and then continued for 5 to 15 seconds at zero current. The above pulse process is repeated 10 to 100 times to obtain CuO x The CuO film prepared in this application x The film is composed of dense CuO x Nanoparticle composition.

[0019] In CuO x The pTTh film is deposited on the film surface, wherein the electrolyte is an acetonitrile solution of 1-100 mmol / L terthiophene and 0.01-1.0 mol / L LiClO4, specifically, the concentration of the terthiophene is 10-50 mmol / L, and the concentration of the LiClO4 is 0.05-0.5 mol / L. The voltage of the cyclic voltammetry electrochemical deposition is 0-1.5 V, and the scan rate is 1-200 mVs -1 , the number of cycles is 1 to 100; specifically, the voltage of the cyclic voltammetry electrochemical deposition is 0 to 1.2 V, and the scan rate is 10 to 100 mV s -1 , the number of cycles is 5 to 50.

[0020] Furthermore, the present invention also discloses the application of the dual-photoelectrode photoelectrochemical cell and the dual-photoelectrode photoelectrochemical cell prepared by the above method in the degradation of organic pollutants and the production of green electricity.

[0021] Beneficial effects:

[0022] 1. The battery relies on light-excited semiconductor photoelectrodes to drive chemical reactions of organic pollutant molecules to generate electricity, which can simultaneously achieve the degradation of pollutants and the production of green electricity.

[0023] 2. This photoelectrochemical cell contains no precious metal catalysts, no diaphragms, no enzymes, and no organic solvents, and has the significant advantages of being cheap, green, and safe.

[0024] 3. The battery uses solar energy as its energy source, degrades pollutants and discharges at room temperature, providing a new direction for future energy conversion devices and environmental pollutant control. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The scanning electron microscope images of the electrode materials prepared in Example 1 include (a) a scanning electron microscope image of a TiO2 film and (b) a scanning electron microscope image of a TiO2 / ZnO film;

[0026] Figure 2The scanning electron micrographs of the electrode materials prepared in Example 2, including (a) the scanning electron micrograph of pure carbon paper (CP), (b) the scanning electron micrograph of CuO x Scanning electron microscopy images of thin films deposited on carbon paper, (c) CuO x SEM images of / pTTh films;

[0027] Figure 3 X-ray diffraction pattern of the electrode material prepared by the present invention, wherein (a) TiO2 / ZnO; (b) CuO x / pTTh;

[0028] Figure 4 TiO2 / ZnO and CuO prepared by the present invention x UV-visible diffuse reflectance spectrum of the Mg / pTTh electrode;

[0029] Figure 5 (a) Voltage-current discharge curves of a single photoelectrochemical cell and two photoelectrochemical cells connected in parallel or in series under illumination conditions of the present invention; (b) Power-current discharge curves;

[0030] Figure 6 The present invention shows a photoelectrochemical cell that degrades rhodamine B dye while driving an LED lamp in the shape of the letters "HN" in the Hainan University logo to emit light, including: (a) three photoelectrochemical cells connected in series to drive the LED lamp to emit light under dark and light conditions; (b) the UV-visible absorption curve of the cell solution during the degradation of rhodamine B by the photoelectrochemical cell; and (c) the color change of the cell solution during the degradation of rhodamine B.

[0031] Figure 7 The results show the cycle stability and cycle discharge power of the single-cell photoelectrochemical cell for degradation of Rhodamine B. DETAILED DESCRIPTION

[0032] In order to better explain the present invention, the main contents of the present invention are further illustrated below in conjunction with specific examples, but the contents of the present invention are not limited to the following examples.

[0033] Example 1

[0034] This embodiment discloses a method for preparing a TiO2 / ZnO photoelectrode, comprising the following steps:

[0035] 1) Add 0.4 mL of tetrabutyl titanate to 40 mL of 6 mol / L HCl solution and stir for 30 minutes. Transfer the resulting mixed solution to a 100 mL autoclave, place a pre-cleaned piece of FTO conductive glass (1 cm x 3 cm), seal the autoclave, and heat at 180°C for 100 minutes. After the reaction, anneal the grown film in a muffle furnace at 450°C for 3 hours to obtain a TiO2 thin film electrode.

[0036] 2) preparing an aqueous solution of 5 mmol / L ZnAc2·2H2O and 5 mmol / L Zn(NO3)3·6H2O as an electrolyte; taking the TiO2 thin film electrode synthesized in step 1), a platinum sheet, and a saturated calomel electrode as a working electrode, a counter electrode, and a reference electrode, respectively, and depositing a ZnO thin film on the TiO2 thin film using a three-electrode system; electrodeposition was performed at a bias voltage of -1 V for 180 s. After deposition, the impurity ions remaining on the surface of the working electrode were rinsed with deionized water, and then the electrode was dried at 80°C and annealed at 450°C for 3 h to obtain a TiO2 / ZnO photoelectrode.

[0037] Example 2

[0038] This embodiment discloses a CuO x / The preparation method of pTTh photoelectrode comprises the following steps:

[0039] 1) Carbon paper (size 1cm*3cm), platinum sheet and saturated calomel electrode were used as working electrode, counter electrode and reference electrode respectively. The electrolyte consisted of 0.1mol / L Cu(NO3)2 and 2mol / L lactic acid. CuO was synthesized on carbon paper by pulse electrodeposition. x Thin film; pulse electrodeposition conditions are: -50mA cm -2 The deposition was carried out under the condition of 1s, and then continued under the condition of zero current for 7s. This pulse process was repeated 25 times to obtain CuO x film;

[0040] 2) Take the CuO deposited in step 1) x The thin film electrode was used as the working electrode, the platinum sheet was used as the counter electrode, the saturated calomel electrode was used as the reference electrode, and the acetonitrile solution containing 10mmol / L terthiophene and 0.10mol / LLiClO4 was used as the electrolyte. The CuO x pTTh thin film is grown on the film to obtain CuO x / pTTh photoelectrode, the voltage range of cyclic voltammetry was 0-1.2 V, and the scan rate was 25 mV s -1 , the number of cycles is 15.

[0041] Example 3

[0042] This embodiment discloses the TiO2 / ZnO photoelectrode and pTTh / CuO prepared in Example 1 and Example 2. x Characterization of the morphology, structure, phase and light absorption properties of the photoelectrode.

[0043] Figure 1 Scanning electron micrographs (SEM) of TiO2 and TiO2 / ZnO show that the TiO2 microstructure is a one-dimensional nanorod array, uniformly, densely, and vertically grown on the FTO substrate. Depositing a thin layer of ZnO on the TiO2, as shown in Figure (b), reveals a dense coating of the ZnO film on the TiO2 nanorods.

[0044] Figure 2 Pure carbon paper, CuO x Thin film, CuO x SEM image of the CuO / pTTh film. The surface of the carbon paper (CP) substrate presents a unique three-dimensional fiber network structure with high conductivity and high surface area, as shown in Figure (a); x After deposition on carbon paper, it can be seen that the surface of the carbon paper is covered with a dense layer of CuO x Particle film layer, see Figure (b); further deposition of pTTh, the resulting CP / CuO x / pTTh electrode, the surface presents a nanoflower morphology composed of two-dimensional nanosheets, which is the unique three-dimensional morphology of pTTh, see Figure (c).

[0045] Figure 3 In order to characterize the phase of the material by X-ray diffractometer, Figure (a) is the X-ray diffraction pattern (XRD) of TiO2 / ZnO. Compared with the XRD standard pattern JCPDS No. 21-1276, it can be seen that the prepared TiO2 film is rutile phase titanium dioxide. The XRD characteristic peaks at 36.55°, 63.21° and 70.20° correspond to the (101), (002) and (112) crystal planes of rutile TiO2, respectively. The other XRD diffraction peaks are the diffraction peaks of SnO2, the chemical composition of the FTO conductive substrate. It is worth noting that for the TiO2 / ZnO composite film sample, no XRD characteristic diffraction peaks from ZnO were observed. This may be due to the poor crystallinity or low content of ZnO in the TiO2 / ZnO electrode, which cannot be detected by XRD characterization technology. Figure (b) is CuO x / pTTh, for CuO x Deposited thin film samples (CP / CuO x ), the characteristic peaks at 35.5° and 38.9° are attributed to CuO, and the characteristic peak at 43.1° is attributed to Cu. The results show that the deposited CuO xComposed of copper compounds of different valence states. For pTTh deposited electrodes (CP / CuO x / pTTh and CP / pTTh), no new diffraction peaks appeared except the peaks from the carbon paper (CP) substrate, which indicated that the obtained pTTh should be amorphous and x CuO cannot be detected on the pTTh electrode x This may be because the pTTh film is on the surface of the electrode and the pTTh film is relatively thick while CuO x The content of interlayer is relatively low, which masks the CuO x characteristic peaks.

[0046] Figure 4 TiO2 / ZnO photoelectrode and CuO x The UV-visible absorption spectrum of the TiO2 / ZnO photoelectrode shows that the TiO2 / ZnO photoelectrode can only absorb sunlight with a wavelength below 410nm (basically ultraviolet light). x The absorption range of the / pTTh photoelectrode can be extended to 635nm, which can absorb most visible light. It can be seen from the light absorption curves of the two electrodes that the two photoelectrodes can complement each other in light absorption.

[0047] Example 4

[0048] This embodiment discloses the discharge performance and dye degradation performance characterization of a dual-photoelectrode photoelectrochemical cell that light-drivenly degrades organic pollutants and simultaneously releases electrical energy.

[0049] The TiO2 / ZnO photoelectrode prepared in Example 1 was used as a photoanode and the CuO prepared in Example 2 was used as a photoanode. x The pTTh photoelectrode is placed opposite the photocathode in a cuvette filled with 4 mL of 10 mg / mL Rhodamine B and 1 mol / L NaOH solution. This constitutes a photoelectrochemical cell. Two or more photoelectrochemical cells can be connected in parallel or in series by connecting them with copper wire. When the cell is working, the Xe light source (100 mW / cm 2 ) is irradiated vertically from one side of the glass window of the cuvette onto the surface of the TiO2 / ZnO photoelectrode. The filtered light after the TiO2 / ZnO photoelectrode absorbs the light is irradiated onto the CuO x / pTTh photoelectrodes, light excites the electron-hole pairs generated at the two electrodes, causing them to separate and migrate under the influence of the built-in electric field and the Fermi level difference, driving the solution molecules on the electrode surfaces to undergo redox reactions, achieving external discharge. At the same time, under light conditions, the photoanode and photocathode are excited to produce active electrons and holes. Organic pollutants are degraded by directly oxidizing them with holes or indirectly by generating oxygen-containing active free radicals through electron / hole-driven solution reactions.

[0050] Figure 5 (a) Voltage-current discharge curves; (b) Power-current discharge curves for a single photoelectrochemical cell and two photoelectrochemical cells connected in parallel or in series under illumination conditions of the present invention. As can be seen from the figure, the single photoelectrochemical cell can achieve an open circuit voltage of 1.0 V and a short circuit current density of 1.5 mA / cm 2 , the maximum discharge power density can reach 0.38mW / cm 2 When two photoelectrochemical cells are connected in series, the open-circuit voltage and power density are twice that of a single cell, while the short-circuit current density remains unchanged. When two photoelectrochemical cells are connected in parallel, the open-circuit voltage remains the same as that of a single cell, while the short-circuit current density and power density are 1.9 times that of a single cell. This indicates that when multiple photoelectrochemical cells are connected in series or parallel, circuit performance loss is minimal.

[0051] Figure 6 For this invention, three photoelectrochemical cells were connected in series to explore the degradation of the Rhodamine B dye and to drive the "HN"-shaped LED light group in the Hainan University logo to emit light. As can be seen from the figure, when the battery is in the dark, the "HN" LED light group does not emit light; once illuminated, the "HN" LED light group is instantly illuminated. During the continuous illumination of the LED light group, the red color of the Rhodamine B solution can be seen to gradually fade, and after 2 hours, it becomes basically colorless. The ultraviolet-visible light absorption intensity of the Rhodamine B solution also gradually decreases to 0. This shows that the discharge process of the photoelectrochemical cell is also the process of dye degradation, reflecting the dual application of the photoelectrochemical cell in producing green electricity and treating environmental pollutants.

[0052] Figure 7 The cyclic stability and cyclic discharge power of the single-cell photoelectrochemical cell of the present invention for the degradation of rhodamine B are shown. In this cell system, each degradation of rhodamine B takes approximately two hours. After each degradation, a new rhodamine B solution is replaced, and the degradation is repeated five times. As can be seen from the figure, the decolorization rate of rhodamine B can reach over 95% after five consecutive degradation cycles, with no significant decrease in the degradation rate. In addition, the discharge power of the photoelectrochemical cell does not drop significantly during each degradation process, maintaining at 0.35-0.4 mW / cm 2 .

[0053] Rhodamine B can be continuously degraded during the battery discharge process, indicating that the battery can degrade organic pollutants while discharging, and has certain application prospects in the utilization and decomposition of organic pollutants.

[0054] In summary, the dual-photoelectrode photoelectrochemical cell designed in the present invention can realize the dual-functional application of light-driven degradation of organic pollutants and simultaneous release of green electricity. Moreover, the photoelectrochemical cell contains no precious metals, no diaphragms, no enzymes, and no organic solvents, and has the significant advantages of being cheap, green, safe, and easy to implement on a large scale.

[0055] The above embodiments are merely preferred examples and are not intended to limit the embodiments of the present invention. In addition to the above embodiments, the present invention has other embodiments. Any technical solution formed by equivalent substitution or equivalent transformation falls within the scope of protection claimed by the present invention.

Claims

1. A method for degrading organic pollutants while releasing electrical energy using a light-driven dual-photoelectrode photoelectrochemical cell, characterized in that: TiO2 / ZnO as photoanode, CuO x / pTTh as photocathode, TiO2 / ZnO photoanode, CuO x The pTTh photocathode is placed in an electrolyte solution containing organic pollutants, and the external circuit is connected to the electrical device through a wire to form a closed loop. Under light conditions, it degrades organic pollutants and produces green electricity. The organic pollutants include any one or more of dye pollutants, pesticide pollutants or pharmaceutical pollutants; The TiO2 / ZnO photoanode comprises a TiO2 nanorod film synthesized on a conductive substrate and a ZnO film deposited on the TiO2 nanorod film, wherein the TiO2 nanorod film is a TiO2 nanorod vertically arranged in an array on the conductive substrate, and the ZnO film is composed of dense ZnO nanoparticles; The CuO x / pTTh photocathode comprises CuO deposited on a conductive substrate x Thin films and deposited on CuO x Flower-like pTTh film on the film, the CuO x The film is composed of dense CuO x The pTTh film is composed of three-dimensional pTTh flowers; The preparation method of the TiO2 / ZnO photoanode comprises the following steps: 1) Tetrabutyl titanate and hydrochloric acid having a concentration of 4 to 8 mol / L are mixed at a volume ratio of 1% to 10%, and the resulting mixed solution is transferred to an autoclave containing a conductive substrate, heated at a temperature of 160 to 180°C for 80 to 100 minutes, and annealed at a temperature of 300 to 600°C for 1 to 10 hours to obtain a TiO2 nanorod film; 2) electrochemically depositing a ZnO thin film using an aqueous solution of 1-25 mmol / L zinc acetate dihydrate and 1-25 mmol / L zinc nitrate hexahydrate as an electrolyte, a TiO2 nanorod film as a working electrode, a platinum sheet as a counter electrode, and a saturated calomel as a reference electrode at a voltage of -1.5 to -1 V for 150 to 350 s, followed by annealing at a temperature of 400 to 500°C for 1 to 5 h to obtain a TiO2 / ZnO photoanode; The CuO x The preparation method of the pTTh photocathode comprises the following steps: 3) Pulse electrodeposition was performed in an electrolyte consisting of 0.1-0.2 mol / L copper nitrate and 1.8-2.5 mol / L lactic acid using a conductive substrate, a platinum sheet, and a saturated calomel as the working electrode, counter electrode, and reference electrode, respectively. The pulse electrodeposition was performed at -60-30 mA cm -2 Deposition was performed for 1 to 5 seconds, followed by 5 to 15 seconds at zero current, and the pulse process was repeated 10 to 100 times to obtain CuO. x film; 4) CuO x The film was used as the working electrode, platinum sheet as the counter electrode, saturated calomel electrode as the reference electrode, 10~50 mmol / L terthiophene and 0.05~0.5 mol / L LiClO4 in acetonitrile as the electrolyte, and the CuO film was deposited on the CuO film by cyclic voltammetry electrochemical deposition method. x The film deposition was carried out by cyclic voltammetry electrochemical deposition with a voltage of 0-1.2 V and a scan rate of 10-100 mV s -1 , the number of cycles is 5~50, and CuO is obtained x / pTTh photocathode.

2. The method according to claim 1, characterized in that The conductive substrate in the TiO2 / ZnO photoanode is FTO conductive glass; the CuO x The conductive substrate in the pTTh photocathode is carbon paper.

3. The method according to claim 1, characterized in that The concentration of the organic pollutants is above 10 mg / mL.

4. The method according to claim 1, wherein The dye pollutants include any one or more of rhodamine B, methyl blue, and methyl orange.

5. The method according to claim 1, wherein The pesticide pollutants include any one or more of organophosphorus pesticides, organochlorine pesticides, and organonitrogen pesticides.

6. The method according to claim 1, characterized in that The pharmaceutical pollutants include any one or more of tetracyclines and penicillins.

7. The method according to claim 1, characterized in that The pharmaceutical contaminants include p-chlorophenol.

8. The method according to claim 1, characterized in that The conductive wire comprises any one of Cu, Ni and Ti metals, and is in the shape of any one of sheet, foil, mesh and wire.

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