Preparation and application of cadmium selenide quantum dot / graphene sensitized titanium dioxide nanorod photo-anode

Abstract

The invention discloses preparation and application of a cadmium selenide quantum dot / graphene sensitized titanium dioxide nanorod photo-anode. The method comprises the following steps: preparing a cadmium selenide quantum dot solution; preparing PDDA modified graphene; preparing a cadmium selenide quantum dot and graphene composite material; preparing a titanium dioxide nanorod growing on the FTO conductive glass; preparing a cadmium selenide quantum dot and graphene composite material sensitized titanium dioxide nanorod photo-anode; the preparation method is simple and feasible, and the raw materials are economical; the prepared cadmium selenide quantum dot / graphene sensitized titanium dioxide nanorod photo-anode has good visible light response capability, and when the cadmium selenide quantum dot / graphene sensitized titanium dioxide nanorod photo-anode is applied to a photocatalytic fuel cell, the power density of 187.65 mu w / cm < 2 > can be reached, so that the cadmium selenide quantum dot / graphene sensitized titanium dioxide nanorod photo-anode has a good market application prospect.

Description

Technical Field

[0001] The present invention relates to the preparation and application of a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode, belonging to the field of photoelectrocatalysis. Background Art

[0002] With the continuous development of global society, the growth of the population has driven an unprecedented demand for resources, especially energy. Among renewable energy options, solar energy is widely regarded as the most abundant and environmentally sustainable energy source. If it can be effectively utilized, it may be possible to solve key problems such as resource depletion and environmental pollution. However, the current utilization rate of solar energy is very low, and the most important way to utilize solar energy on Earth is still the photosynthesis of plants. Therefore, converting solar energy into energy that can be currently utilized by humans is the most promising way to solve resource and environmental problems. To utilize solar energy, people have developed various methods such as photovoltaic power generation and photocatalysis. Recent technological advancements have also spawned a variety of technologies that can directly convert solar energy into electrical energy, such as solar cell (PC) technology. Although solar energy is the energy source with the largest reserve and significant progress has been made in solar cell technology, it still faces many challenges in practical applications. For example, in some solar cells, although the catalytic material can exhibit high visible light absorption efficiency and the theoretical power conversion efficiency can reach 44%, the actual light conversion efficiency is not high, which makes it difficult for the solar cell itself to output a high power.

[0003] To address the limitations of single energy conversion technologies, researchers have begun to explore innovative methods that integrate multiple energy conversion pathways, aiming to achieve more efficient and sustainable energy utilization. Among them, designing systems that can simultaneously convert solar energy and chemical energy into electrical energy has become a research hotspot. Based on this concept, the photocatalytic fuel cell (PFC) has emerged. Such cells ingeniously combine the principles of fuel cells (FC) and solar cells (PC) and achieve dual energy conversion through the synergistic effect of photocatalysis and electrochemical reactions.

[0004] In PFC, many photocatalytic materials (such as titanium dioxide, carbon nitride, etc.) are used to absorb sunlight and generate electron-hole pairs, thereby driving electrochemical reactions. At the same time, the fuel cell part utilizes the chemical energy of fuels (such as hydrogen, methanol or glucose) to generate electrical energy through redox reactions. This dual energy conversion mechanism not only significantly improves the power output of the system, but also greatly enhances the overall energy utilization efficiency. Research shows that compared with traditional fuel cells or solar cells, PFC can achieve higher energy density and longer operating time under the same conditions. However, the development of photocatalytic fuel cells is still in its infancy, and there are still many problems to be solved. In the PFC system, the photoanode is undoubtedly one of the most important components. The photoanode needs to play the roles of both an electrocatalyst and a photocatalyst to complete FC and PC activities. Therefore, selecting a suitable photocatalyst has become the focus of this work. Summary of the Invention

[0005] The object of the present invention is to overcome the deficiencies in the prior art and provide a preparation and application of a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod (CdSe QDs-PGR / TiO2 NRAs / FTO) photoanode. The prepared cadmium selenide quantum dot and graphene composite material CdSe QDs-PGR is used as a TiO2 sensitizer for the photoanode of a photocatalytic fuel cell, which can effectively broaden the spectral absorption range of TiO2 to visible light and effectively generate a phenomenon of photoinduced charge separation. The cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod (CdSe QDs-PGR / TiO2 NRAs / FTO) photoanode can effectively generate photocurrent and catalyze the oxidation of ascorbic acid. The assembled battery can reach a power density of 187.65 μW / cm 2 and has good market application prospects.

[0006] To solve the above technical problems, the present invention is implemented by adopting the following technical solutions: In the first aspect, the present invention provides a preparation method of a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode (CdSe QDs-PGR / TiO2 NRAs / FTO), which includes the following steps: (1) Prepare a cadmium selenide quantum dot solution; Disperse a certain amount of selenium powder in an anhydrous sodium sulfite solution to obtain a Na2SeSO3 solution; disperse mercaptoacetic acid in a CdCl2 solution and adjust it to alkaline. At a certain temperature, quickly inject the Na2SeSO3 solution into the CdCl2 solution containing mercaptoacetic acid. After reacting for a period of time, a cadmium selenide quantum dot solution is obtained; Preferably, first mix selenium powder with anhydrous sodium sulfite, add 20 ml of water as a solvent, continuously stir while heating at 90 °C, after the reaction is completed, add ultrapure water to make up to 50 ml to obtain a Na2SeSO3 solution; add mercaptoacetic acid to the CdCl2 solution, then use 0.5 M NaOH to adjust the pH to 10, and add ultrapure water to make up to 50 ml. Rapidly inject the Na2SeSO3 solution into the CdCl2 solution containing mercaptoacetic acid under heating, continuously heat for 1 hour, after the reaction is completed, obtain a CdSe QDs solution; (2) Prepare PDDA-modified graphene; Mix the graphene oxide solution and the PDDA solution, add hydrazine hydrate and carry out a heating reaction; then repeatedly wash and centrifuge the reaction solution to obtain a black solid; Freeze-dry the black solid under vacuum to obtain PDDA-modified graphene; Preferably, place the graphene oxide solution and 20% PDDA solution in a 250 mL flask, stir evenly at room temperature for 30 min, then add 0.5 mL of 80% hydrazine hydrate to the flask, and stir for 24 h under heating conditions; repeatedly wash and centrifuge the reaction solution with ionized water to wash away the unreacted hydrazine hydrate. Finally, freeze-dry the obtained black solid under vacuum to obtain a dry PDDA-GR solid, add ultrapure water and ultrasonically disperse it evenly to obtain a 0.1 mg / ml PDDA-GR dispersion; (3) Prepare a cadmium selenide quantum dot / graphene composite material; Disperse the PDDA-modified graphene in the cadmium selenide quantum dot solution under ultrasonic conditions, and after reacting for a period of time, obtain a cadmium selenide quantum dot / graphene composite material; (4) Prepare titanium dioxide nanorods grown on FTO conductive glass; Add tetrabutyl titanate to hydrochloric acid, stir for a period of time, then add this solution to the reaction kettle, and vertically place the FTO conductive glass at the bottom of the reaction kettle with the conductive side facing the inner wall of the reaction kettle. After thermal reaction, obtain a TiO2 nanorod array grown on the FTO conductive glass; (5) Prepare a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode; Take the cadmium selenide quantum dot / graphene composite material solution, drop-coat it on the FTO electrode grown with TiO2, and after natural drying, obtain a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode.

[0007] In some embodiments, in step (3), an equal volume of cadmium selenide quantum dot solution and PDDA-modified graphene dispersion are taken. While the PDDA-modified graphene dispersion is under ultrasonic treatment, the cadmium selenide quantum dot solution is slowly dropped into it at a rate of 1 - 2 drops per second. After mixing, ultrasonic treatment is continued for 30 min to obtain a cadmium selenide quantum dot / graphene composite material.

[0008] In some embodiments, in step (4), 0.4 ml of tetrabutyl titanate is added to 18% hydrochloric acid, and the mixture is stirred for about 30 minutes. The solution is then added to a 50-ml reaction kettle. The FTO conductive glass is placed vertically at the bottom of the reaction kettle with the conductive side facing the inner wall of the reaction kettle, and heated at 150 °C for 4 hours. After cooling to room temperature, it is taken out and washed to obtain a TiO2 nanorod array grown on the FTO conductive glass.

[0009] In a second aspect, the present invention provides an application of a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode. Preferably, the cadmium selenide quantum dot / graphene composite material is used to sensitize the titanium dioxide nanorod photoanode for photoelectric conversion and catalytic oxidation of ascorbic acid.

[0010] In some embodiments, the application includes the following steps: A 10-ml sealed H-type electrolytic cell is used, and the two chambers are separated by a Nafion117 proton membrane in the middle. 0 - 0.12 M ascorbic acid is added to the PBS electrolyte of the photoanode, and nitrogen is used to remove excess oxygen.

[0011] In some embodiments, the anode light source is a 300-W xenon lamp equipped with an AM1.5G simulated sunlight filter, and the light intensity on the electrode surface is 80 - 100 mW / cm 2 。

[0012] In some embodiments, the cathode uses a Pt / C catalyst.

[0013] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: 1. The present invention proposes the preparation and application of a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode. By modifying graphene with PDDA and CdSe QDs with mercaptoacetic acid, they can be connected by electrostatic adsorption, with reliable connection and improvement of the problem of insufficient conductivity of quantum dots. A rod-shaped TiO2 photoanode is synthesized by high temperature and high pressure in a reaction kettle, which has a large surface area and excellent electron transport efficiency.

[0014] 2. The cadmium selenide quantum dot-graphene composite material (CdSe QDs-PGR) prepared by the present invention has good response to visible light and, as a sensitizer, greatly broadens the spectral absorption range of the TiO2 photoanode; the prepared cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod (CdSe QDs-PGR / TiO2 NRAs / FTO) photoanode can effectively generate photocurrent and catalytically oxidize ascorbic acid in a neutral PBS electrolyte containing ascorbic acid.

[0015] 3. The cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod (CdSe QDs-PGR / TiO2 NRAs / FTO) photoanode prepared by the method of the present invention has a simple synthesis method and low cost. This material exhibits excellent photoelectric conversion ability. It has been verified that this material can broaden the spectral absorption range of TiO2 to 546 nm, and the assembled battery can achieve an energy output of 187.65 μW / cm 2 and an open-circuit potential of 0.75 V under visible light. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 FIG. 11 is an SEM image of the front side of the TiO2 nanorods prepared by the method for preparing a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode provided in Example 1 of the present invention; Figure 2 a is Figure 1 the SEM image of the cross-section of the TiO2 nanorods in FIG. 11, Figure 2 b is Figure 1 the SEM image of the side of the TiO2 nanorods in FIG. 11; Figure 3 FIG. 23 is a TEM image of the cadmium selenide quantum dots prepared by the method for preparing a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode provided in Example 1 of the present invention; Figure 4 FIG. 26 is an XRD pattern of the cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode (CdSe QDs-PGR / TiO2 NRAs / FTO) and TiO2 NRAs / FTO prepared by the method for preparing a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode provided in Example 1 of the present invention; Figure 5 a is the ultraviolet-visible (UV-Vis) absorption spectrum of the cadmium selenide quantum dots (CdSe QDs) prepared by the method for preparing a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode provided in Example 1 of the present invention; wherein, the abscissa is the wavelength and the ordinate is the absorbance; Figure 5 b is the corresponding absorption spectrum of the cadmium selenide quantum dots in Example 2 of the present invention; Figure 5 c is the corresponding absorption spectrum of the cadmium selenide quantum dots in Example 3 of the present invention; Figure 6 a is the luminescence image under ultraviolet light of the composite material of cadmium selenide quantum dots and cadmium selenide quantum dots and graphene prepared by the method for preparing a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode provided in Example 1 of the present invention; Figure 6 b corresponds to Example 2; Figure 6 c corresponds to Example 3; Figure 7 is the power density of the cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode prepared by the method for preparing a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode provided in Example 1 of the present invention under different voltages; Figure 8 is the power density of the cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode prepared by the method for preparing a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode provided in Example 1 of the present invention under different ascorbic acid concentrations. Detailed implementation manners

[0017] The present invention will be further described below with reference to the accompanying drawings. The following examples are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0018] Unless otherwise specified, the experimental methods used in the following examples are the experimental methods without specific conditions noted in the examples, and usually follow conventional conditions. The materials, reagents, etc. used in the following examples can be obtained from commercial channels unless otherwise specified.

[0019] The present invention provides a method for preparing a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode, which is characterized by including the following steps: (1) Prepare a cadmium selenide quantum dot solution; Disperse a certain amount of selenium powder in an anhydrous sodium sulfite solution to obtain a Na2SeSO3 solution; disperse mercaptoacetic acid in a CdCl2 solution, adjust it to alkaline, add the Na2SeSO3 solution, and heat for reaction to obtain a cadmium selenide quantum dot solution; (2) Prepare PDDA-modified graphene; Mix the graphene oxide solution and the PDDA solution, add hydrazine hydrate and carry out a reaction; then wash and centrifuge the reaction solution repeatedly to obtain a black solid; Freeze-dry the black solid under vacuum to obtain PDDA-modified graphene; (3) Prepare a composite material of cadmium selenide quantum dots and graphene; Disperse the PDDA-modified graphene in the cadmium selenide quantum dot solution under ultrasonic conditions, and after reacting for a period of time, obtain a composite material of cadmium selenide quantum dots and graphene; (4) Prepare titanium dioxide nanorods grown on FTO conductive glass; Add tetrabutyl titanate to hydrochloric acid. After stirring for a period of time, add this solution into the reaction kettle, and place the FTO conductive glass vertically at the bottom of the reaction kettle with the conductive side facing the inner wall of the reaction kettle. After thermal reaction, a TiO₂ nanorod array grown on the FTO conductive glass is prepared; (5) Sensitize the titanium dioxide nanorod photoanode with a cadmium selenide quantum dot and graphene composite; Take the cadmium selenide quantum dot and graphene composite solution, drop-coat it onto the FTO electrode grown with TiO₂, and after natural drying, a cadmium selenide quantum dot and graphene composite-sensitized titanium dioxide nanorod photoanode is prepared.

[0020] It should be noted that in step (1), the amount of anhydrous sodium sulfite used is 1.58 g, the amount of the CdCl₂ solution used is 20 ml, the concentration is 5 mM, the amount of mercaptoacetic acid used is 20 μl, and the amount of the Na₂SeSO₃ solution used is 0.5 ml.

[0021] In some embodiments, in step (1), at a temperature of 40 - 100 °C, the Na₂SeSO₃ solution is rapidly injected into the mercaptoacetic acid solution dispersed in the CdCl₂ solution, and heating is continued for 1 - 2 hours.

[0022] The present invention also provides an application of a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode, and the cadmium selenide quantum dot and graphene composite-sensitized titanium dioxide nanorod photoanode is used for photoelectric conversion and catalytic oxidation of ascorbic acid.

[0023] The present invention will be described in detail below through examples, but the protection scope of the present invention is not limited thereto.

[0024] Example 1 A preparation method of a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode, comprising the following steps: (1) Prepare a cadmium selenide quantum dot solution; a. First, mix 0.39 g of selenium powder with 1.58 g of anhydrous sodium sulfite, add 20 ml of water as a solvent, continuously stir while heating at 90 °C, and after the reaction is completed, add ultrapure water to make up to 50 ml to obtain a Na₂SeSO₃ solution; b. Add 20 μl of mercaptoacetic acid to 20 ml of a 5 mM CdCl2 solution, then adjust the pH to 10 using 0.5 M NaOH, and make up to 50 ml with ultrapure water. Rapidly inject 0.5 ml of the Na2SeSO3 solution into the CdCl2 solution containing mercaptoacetic acid at 100 °C, and continue heating for 1 hour. After the reaction is completed, a cadmium selenide quantum dot (CdSe QDs) solution is obtained; (2) Prepare PDDA-modified graphene; a. Place 100 ml of a 5 mg / ml graphene oxide solution and 20% PDDA solution in a 250 mL flask, stir evenly at room temperature for 30 min, then add 0.5 mL of 80% hydrazine hydrate to the flask, and stir for 24 h under heating conditions; b. Wash and centrifuge the reaction solution repeatedly with ionic water to wash away the unreacted hydrazine hydrate. Finally, freeze-dry the obtained black solid under vacuum to obtain a dry PDDA-GR solid, add ultrapure water and disperse it evenly by ultrasonic treatment to obtain a 0.1 mg / ml PDDA-GR dispersion; (3)Prepare cadmium selenide quantum dot and graphene composite (CdSe QDs-PGR); Take equal volumes of the CdSe QDs solution and the PDDA-GR dispersion. While the PDDA-GR dispersion is under ultrasonic treatment, slowly drop the CdSe QDs solution into it, controlling the dropping rate at 1-2 drops per second. After mixing, continue ultrasonic treatment for 30 min to obtain the cadmium selenide quantum dot and graphene composite (CdSe QDs-PGR).

[0025] (4)Prepare titanium dioxide nanorods grown on FTO conductive glass; Add 0.4 ml of tetrabutyl titanate to 10 ml of 18% hydrochloric acid, stir for about 30 minutes, add the solution to a 50 ml reaction kettle, place the FTO conductive glass vertically at the bottom of the reaction kettle, with the conductive side facing the inner wall of the reaction kettle. Heat at 150 °C for 4 hours, take it out and wash it after cooling to room temperature to obtain a TiO2 nanorod array grown on the FTO conductive glass.

[0026] (5)Prepare a cadmium selenide quantum dot and graphene composite-sensitized titanium dioxide nanorod photoanode; Prepare a cadmium selenide quantum dot graphene composite-loaded titanium dioxide nanorod grown on FTO conductive glass (CdSe QDs-PGR / TiO2 NRAs / FTO) photoanode Take 100 μL of the CdSe QDs-PGR solution and directly drop-coat it onto the FTO electrode grown with TiO2, and let it dry naturally to obtain the CdSe QDs-PGR / TiO2 NRAs / FTO photoanode.

[0027] In this embodiment, after the synthesis is completed, SEM characterization is performed on the surface, cross-section, and side of the TiO2 NRAs synthesized in step (4). As shown in Figure 1 , Figure 2 a, Figure 2 b, it shows that TiO2 is a bottom-up vertical growth structure with a height of about 1-2 μm and its growth is very dense.

[0028] The CdSe QDs solution in step (1) b of Example 1 is laid on an ultra-thin copper mesh for transmission electron microscopy (TEM) testing. The TEM image is as shown in Figure 3 . The CdSe QDs have a diameter of 6-8 nm, and at the same time, a lattice fringe of 0.22 nm is found.

[0029] The XRD patterns of TiO2 NRAs / FTO and CdSe QDs-PGR / TiO2 NRAs / FTO in steps (4) and (5) of Example 1 are as shown in Figure 4 . For CdSe QDs-PGR / TiO2 NRAs / FTO, in addition to the characteristic peaks of TiO2 NRAs, the characteristic peaks at about 24°, 25°, and 42° represent the crystal plane diffractions of the (100), (002), and (101) crystal planes of the zinc blende crystal form respectively. Compared with the Figure 3 0.22 nm lattice fringe, it also shows that the CdSe quantum dots are successfully deposited on the surface of TiO2 NRAs.

[0030] The ultraviolet-visible absorption spectrum of the CdSe QDs-PGR prepared in the example is tested. As shown in Figure 5 a, the CdSe QDs-PGR can absorb visible light up to 546 nm.

[0031] The CdSe QDs-PGR and CdSe QDs prepared in the example are irradiated with an ultraviolet lamp. As shown in Figure 6 a, the CdSe QDs can emit red light, and the luminescence intensity of the CdSe QDs-PGR is significantly lower.

[0032] An application of a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode in a photocatalytic fuel cell includes the following steps: The CdSe QDs-PGR / TiO2 NRAs / FTO prepared in Example 1 was placed in a sealed 10-ml H-type electrolytic cell. The two chambers were separated by a Nafion117 proton membrane in the middle. Ascorbic acid with a concentration of 0 - 0.12 M was added to the PBS electrolyte of the photoanode. Excess oxygen was removed using nitrogen. The cathode used a Pt / C catalyst, which was loaded onto a 3-mm glassy carbon electrode. Oxygen was continuously introduced into the cathode PBS electrolyte. The anode light source was provided by a 300-W xenon lamp equipped with an AM1.5G simulated sunlight filter, and the light intensity on the electrode surface was adjusted to 100 mW / cm 2 .

[0033] Summary: The attached results are as Figure 7 、 Figure 8 shown. The results indicate that in the PBS electrolyte containing ascorbic acid, this photoanode can effectively generate photocurrent under light source irradiation and catalyze the oxidation of ascorbic acid. Among them, in the voltage range of 0 - 0.8 V, an energy output of 187.65 μW / cm can be generated at 0.5 V. Meanwhile, within the range of ascorbic acid concentration of 0 - 0.12 M, the highest power density is achieved when the ascorbic acid concentration is 0.1 M. 2 Example 2

[0034] The preparation method of the cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode is the same as that in Example 1 and will not be elaborated here. The differences are as follows: In step (1) b, the heating temperature is 70 °C, and the other steps are the same as those in Example 1.

[0035] The CdSe QDs-PGR prepared in the example was tested for its ultraviolet-visible absorption spectrum. As Figure 5 shown in b, CdSe QDs-PGR can absorb visible light up to 497 nm.

[0036] The CdSe QDs-PGR and CdSe QDs prepared in the example were irradiated with an ultraviolet lamp. As Figure 6 shown in b, CdSe QDs can emit yellow light, and the luminescence intensity of CdSe QDs-PGR is significantly lower.

[0037] For the application of a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode in a photocatalytic fuel cell, except that the CdSe QDs-PGR / TiO2 NRAs / FTO photoanode used was prepared in Example 2, the other steps are the same as those in Example 1 and will not be elaborated here. Example 3

[0038] ​The preparation method of the cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode is the same as that of Example 1, and the differences are as follows: in step (1) b, the heating temperature is 40 °C, and the other steps are the same as those in Example 1.

[0039] The ultraviolet-visible absorption spectrum of the CdSe QDs-PGR prepared in the example was tested. As Figure 5 shown in c, CdSe QDs-PGR can absorb visible light up to 470 nm.

[0040] The CdSe QDs-PGR and CdSe QDs prepared in the example were irradiated with an ultraviolet lamp. As Figure 6 shown in c, CdSe QDs can emit blue-green light, and the luminescence intensity of CdSe QDs-PGR is significantly lower.

[0041] The application of a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode in a photocatalytic fuel cell. Except that the CdSe QDs-PGR / TiO2 NRAs / FTO photoanode used is the one prepared in Example 2, the other steps are the same as those in Example 1 and will not be elaborated here.

[0042] The preparation and application of a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode disclosed by the present invention belong to the field of photoelectrocatalytic technology. Aiming at the problems in the existing photocatalysis field that it is difficult to achieve high-power output and the cost of photoanodes is extremely high, CdSe quantum dots are modified with mercaptoacetic acid, and graphene is modified with PDDA. Through a simple electrostatic adsorption method, a CdSe QDs-PGR composite material is prepared and synthesized to solve the problem of insufficient conductivity of the quantum dots themselves and reduce the occurrence of the phenomenon of photoelectric recombination. As a sensitizer for photoanodes, it can effectively broaden the spectral absorption range. TiO2 NRAs grown on FTO conductive glass are prepared in one step under high temperature and high pressure in a reaction kettle. The synthesis is simple and the cost is low. At the same time, the rod-shaped TiO2 has a higher surface area and a more efficient electron transfer efficiency.

[0043] The CdSe QDs-PGR / TiO2 NRAs / FTO photoanode prepared by the present invention can effectively perform photoelectric conversion in a photocatalytic fuel cell, catalytically oxidize ascorbic acid while generating photocurrent, and greatly improve the power output. Experiments have confirmed that after optimization, the pH of the CdCl2 solution is adjusted to 10, the reaction temperature is 100 °C, the dosage of hydrochloric acid is 10 ml, and the dosage of tetrabutyl titanate is 0.4 ml. That is, Example 1 is the best process parameter. The raw materials of this technology are cheap and easily available, and the process is simple and controllable, providing new ideas for the development of clean energy materials.

[0044] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode, characterized in that, It includes the following steps: (1) Prepare a cadmium selenide quantum dot solution; Disperse a certain amount of selenium powder in an anhydrous sodium sulfite solution to obtain a Na2SeSO3 solution; disperse mercaptoacetic acid in a CdCl2 solution and adjust it to be alkaline. At a certain temperature, quickly inject the Na2SeSO3 solution into the CdCl2 solution containing mercaptoacetic acid. After reacting for a period of time, a cadmium selenide quantum dot solution is prepared; (2) Prepare PDDA-modified graphene; Mix the graphene oxide solution and the PDDA solution, add hydrazine hydrate and carry out a heating reaction. Then, wash and centrifuge the reaction solution repeatedly to obtain a black solid; Freeze-dry the black solid under vacuum to obtain PDDA-modified graphene; (3) Prepare a composite material of cadmium selenide quantum dots and graphene; Disperse the PDDA-modified graphene in the cadmium selenide quantum dot solution under ultrasonic conditions. After reacting for a period of time, a composite material of cadmium selenide quantum dots and graphene is prepared; (4) Prepare titanium dioxide nanorods grown on FTO conductive glass; Add tetrabutyl titanate to hydrochloric acid and stir for a period of time. Then, add this solution to the reaction kettle, and place the FTO conductive glass vertically at the bottom of the reaction kettle with the conductive side facing the inner wall of the reaction kettle. After a thermal reaction, a TiO2 nanorod array grown on the FTO conductive glass is prepared; (5) Prepare a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode; Take the composite material solution of cadmium selenide quantum dots and graphene, drop-coat it onto the FTO electrode grown with TiO2, and let it dry naturally to obtain a cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode.

2. The preparation method of the cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode according to claim 1, characterized in that, In step (1), the mass ratio of the selenium powder to the anhydrous sodium sulfite is 1-10, and the concentration of the CdCl2 solution is 2-10 mM.

3. The preparation method of the cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode according to claim 2, characterized in that, In step (1), the amount of anhydrous sodium sulfite used is 1.58 g, the amount of the CdCl2 solution used is 20 ml, the concentration is 5 mM, the amount of mercaptoacetic acid used is 20 μl, and the amount of the Na2SeSO3 solution used is 0.5 ml.

4. The preparation method of the cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode according to claim 3, characterized in that, In step (1), at a temperature of 40-100 °C, quickly inject the Na2SeSO3 solution into the CdCl2 solution containing mercaptoacetic acid and continuously heat for 1-2 hours.

5. The preparation method of the cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode according to claim 1, characterized in that, In step (3), take equal volumes of the cadmium selenide quantum dot solution and the PDDA-modified graphene dispersion. Under ultrasonic conditions, slowly drop the cadmium selenide quantum dot solution into the PDDA-modified graphene dispersion, controlling 1-2 drops per second. After mixing, continue ultrasonic treatment for 30 min to obtain a composite material of cadmium selenide quantum dots and graphene.

6. The preparation method of the cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode according to claim 1, characterized in that, In step (4), add 0.4 ml of tetrabutyl titanate to 18% hydrochloric acid and stir for about 30 minutes. Add the solution to a 50 ml reaction kettle. Place the FTO conductive glass vertically at the bottom of the reaction kettle with the conductive side facing the inner wall of the reaction kettle, and heat at 150 °C for 4 hours. After cooling to room temperature, take it out and wash it to obtain a TiO2 nanorod array grown on the FTO conductive glass.

7. Use of the cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode obtained by the preparation method according to claim 1, characterized in that, The cadmium selenide quantum dot / graphene-sensitized titanium dioxide nanorod photoanode is used for photoelectric conversion and catalytic oxidation of ascorbic acid.

8. The application according to claim 7, characterized in that It includes the following steps: A 10-ml sealed H-type electrolytic cell was used, with a Nafion 117 proton membrane in the middle to separate the two chambers. Ascorbic acid with a concentration of 0 - 0.12 M was added to the PBS electrolyte of the photoanode, and nitrogen was used to remove excess oxygen.

9. The application according to claim 8, characterized in that, The anode light source is a 300W xenon lamp equipped with an AM1.5G simulated sunlight filter, and the light intensity on the electrode surface is 80 - 100 mW / cm 2 .

10. The application according to claim 9, characterized in that, The cathode used a Pt / C catalyst.

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