Self-luminous photoelectric synergistic catalytic oxidation electrode and application thereof

Abstract

The invention discloses a self-luminous quantum dot photoelectric synergistic catalytic oxidation electrode which is sequentially composed of a substrate, a hole transport layer, a quantum dot layer and a catalytic material layer from bottom to top. Or the quantum dot catalytic material co-doped solar cell is composed of the substrate, the hole transport layer, the quantum dot catalytic material co-doped layer and the electron blocking layer from bottom to top in sequence; the electrode can be effectively coupled with the photoelectrocatalysis effect, the catalytic reduction efficiency of the electrode and the sensing detection performance of reducing pollutants are improved, and wastewater and waste gas treatment, electrochemical synthesis and electrochemical detection can be achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrocatalytic materials, and particularly relates to a self-luminous quantum dot photoelectric synergistic catalytic oxidation electrode and application thereof. BACKGROUND

[0002] Photoelectrocatalytic reaction has attracted much attention due to its less secondary pollution, low cost, simple process and the like. For example, patent CN111589460A discloses a W 18 O 49 / BiOX composite photocatalytic material, wherein X is chlorine, bromine or iodine. The W 18 O 49 / BiOX composite photocatalytic material can effectively separate photo-generated carriers and improve catalytic efficiency. However, the photoelectric detection device of the above-mentioned composite photocatalytic material is not good enough in photoelectric response ability in a wide spectral range (375-800 nm). Patent CN202110178404.X discloses a titanium dioxide photoelectrode with three-dimensional crystal face junction properties and preparation and application thereof. A titanium mesh is used as a titanium source, hydrochloric acid is used as a morphology control agent, and hydrogen peroxide is used as an oxidizing agent. One-dimensional upright rutile TiO2 nanorods with top {111} crystal face exposure are grown in situ on the titanium mesh substrate by a gas-phase hydrothermal method. Then, {101}, {111} nanosheets are grown outside the nanorods by secondary hydrothermal method, forming a three-dimensional crystal face junction structure. The electrode has high photoelectrocatalytic degradation performance, but TiO2 itself is still limited by the problem of limited light response range. The article published by Van Dien Dang et al. in Applied Catalysis B: Environmental uses nitrogen-doped carbon dots (NCD) anchored g-C3N4 / α-Fe2O3 (CNFO) shell / core nanocomposites for photocatalytic degradation of trimethoprim (TMP) and hydrogen production. NCD is mainly used as an electronic intermediate to promote the recombination of Fe2O3 conduction band electrons and g-C3N4 valence band holes, retain the strong reduction electrons of the g-C3N4 conduction band (generate ·O2⁻) and the strong oxidation holes of the Fe2O3 valence band (generate ·OH), effectively promote the degradation of TMP (95%) and make the hydrogen production rate reach 850 μmol / (cm 2·h), but in this system, an external light source is used, and in practical applications, the dependence on external light source is strong, so the light conversion efficiency (PCE) is only 0.32%, which is far from the ideal value (>10%). The traditional photoelectrocatalytic anode material uses an external light source, has the problems of narrow light absorption range, high carrier recombination rate and poor stability, and in practical application, an external light source needs to be additionally set, and in the environment, most of the light cannot effectively penetrate due to the propagation medium, so it cannot reach the surface of the catalyst to excite its catalytic activity. These problems lead to the fact that the photoelectric synergistic catalysis technology cannot be widely used in the fields of wastewater treatment, electrochemical synthesis and electrochemical detection, and how to solve the problem of weak or no light in the actual environment affecting the catalytic performance is the top priority of the photoelectric synergistic catalysis technology. SUMMARY

[0003] The application provides a self-luminous quantum dot photoelectric synergistic catalytic oxidation electrode, which is applied as an anode in wastewater and waste gas treatment, electrochemical synthesis and electrochemical detection, and realizes efficient catalysis and stable operation in weak light or no light environment.

[0004] The self-luminous quantum dot photoelectric synergistic catalytic oxidation electrode comprises, from bottom to top, a substrate, a hole transport layer, a quantum dot layer and a catalytic material layer; or comprises, from bottom to top, a substrate, a hole transport layer, a quantum dot catalytic material co-doped layer and an electron blocking layer. The substrate is one of carbon cloth, titanium mesh and ITO glass; the hole transport layer material is one of TiO2 nanotube array, cobalt tetracarboxy phthalocyanine and CuO nanosheet array; the quantum dot layer material is one of CdSe quantum dots, nitrogen-sulfur co-doped graphene quantum dots, a composite of CsPbBr3 quantum dots and boron nitride; the catalytic material layer is one of platinum nanoparticles, cerium-doped tungsten oxide nanomaterial and nickel oxide; and the material in the electron blocking layer is zinc oxide.

[0005] The preparation method of the hole transport layer is one of constant-voltage anodization, solid-phase synthesis, electrodeposition and spin coating.

[0006] The preparation method of the quantum dot layer is one of successive ionic layer adsorption reaction (SILAR), thermal injection, hydrothermal method, in-situ doping and spin coating, so as to ensure that the wavelength <400 nm is excited by electroluminescence effect.

[0007] The preparation method of the catalytic material layer is one of electrodeposition, sol-gel calcination, in-situ doping and atomic layer deposition.

[0008] The technical advantage of the application lies in that: (1) the self-luminous characteristic of the quantum dots widens the light absorption range, and the electroluminescence effect enhances the concentration of photo-generated carriers; (2) The electrode material constructed in different structures has the advantages of high charge separation efficiency and high charge transfer rate, and the reaction catalytic efficiency is higher than that of ordinary electrodes; (3) Compared with traditional photocatalytic materials and photoelectrocatalytic materials, the application scene is more widely, and the electrode of the self-luminous material prepared on the traditional photocatalytic material is proposed, and the photoelectrocatalytic reaction can be carried out in a complex environment. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 It is a structural schematic diagram of the self-luminous quantum dot photoelectric synergistic catalytic oxidation electrode; Figure 2 It is a degradation rate schematic diagram of ciprofloxacin in Example 1; Figure 3 It is a linear voltammetry scan diagram in Example 2; Figure 4 It is a glycerol conversion rate schematic diagram in Example 3. DETAILED DESCRIPTION

[0010] The application will be described in detail below in combination with specific embodiments, but the protection scope of the application is not limited to the content described; the method in the examples is a conventional method unless otherwise specified.

[0011] Example 1: The self-luminous quantum dot photoelectric synergistic catalytic oxidation electrode and photoelectrocatalytic degradation of ciprofloxacin in wastewater In this embodiment, titanium mesh is used as a base layer, TiO2 nanotube array is used as a hole transport layer material, CdSe is used as a quantum dot layer material, and platinum nanoparticles are used as a catalytic material.

[0012] 1. Base layer treatment TA1 grade pure titanium mesh (specification 100x100x0.20mm, rhombic hole long axis 1.00mm) was selected, placed in a polytetrafluoroethylene beaker containing a mixture of acetone-isopropyl alcohol (V / V=3:1), treated in a 40kHz ultrasonic tank at 25℃ for 10 minutes, repeated three times to ensure both sides clean; after washing with ultrapure water for 120s, immersed in an etching solution (40% HF:68% HNO3:H2O=1:6:8, v / v) at 20℃ for 120s, immediately transferred to a 5wt% boric acid solution for 30s, and then transferred to a 0.1M Na2CO3 solution for 60s to terminate the reaction; 2. Hole transport layer TiO2 nanotube arrays were prepared by constant voltage anodization. 99.8% ethylene glycol was placed in a double-layer glass reactor, and 0.5% NH4F by volume of ethylene glycol and 3% ultrapure water by volume of ethylene glycol were added. The solution was dissolved by magnetic stirring at 400 rpm for 30 minutes, and then high-purity nitrogen (99.99%) was bubbled to remove oxygen for 30 minutes to obtain an ethylene glycol electrolyte. A titanium mesh was fixed as an anode on a clamp and immersed in the above-mentioned ethylene glycol electrolyte. A platinum sheet was used as a cathode, a direct current source was connected, a voltage of 30V was set, the solution temperature was maintained at 15℃ (by external refrigeration circulator), 200 rpm magnetic stirring and 0.5 L / min solution external circulation were started at the same time, and the titanium mesh was taken out after 4 hours. A dense blue nanotube layer was formed on the surface. Immediately, an injection syringe was used to inject ultrapure water to replace the electrolyte, and the titanium mesh was washed three times. Then, the titanium mesh was immersed in a 0.01M (NH4)2SO4 solution for 10 minutes, and then immersed in anhydrous ethanol for 5 minutes. The titanium mesh was placed in a muffle furnace and heated to 450℃ at a rate of 5℃ / min. The temperature was maintained for 2 hours, and then the furnace was cooled to below 80℃. The hole transport layer was formed on the titanium mesh substrate. 3. Preparation of CdSe quantum dot layer A continuous ion layer adsorption reaction (SILAR) was used, which was carried out in a nitrogen-filled glove box (O2<0.1ppm, H2O<0.1ppm). A 0.05M cadmium acetate ethanol solution and a 0.05M Na2SeO3 methanol solution (oxygen was removed by nitrogen bubbling for 30 minutes) were prepared. A titanium mesh with a hole transport layer prepared in step 2 was clamped with a polytetrafluoroethylene forceps and immersed in the cadmium acetate ethanol solution for 30 seconds, taken out and placed above the liquid surface for 5 seconds, moved into anhydrous ethanol for 15 seconds, and vertically blown with a nitrogen gun (0.15MPa) for 20 seconds. Then, the titanium mesh was moved into the Na2SeO3 methanol solution for 30 seconds, rinsed with methanol for 15 seconds, and dried with nitrogen. This was one SILAR cycle. After 20 cycles, the titanium mesh was moved into a tube furnace and heated at 180℃ for 30 minutes under N2 / H2 mixed gas (95:5), and then heated to 240℃ for 90 minutes. A CdSe quantum dot layer was formed on the hole transport layer. 4. Preparation of catalytic material layer Platinum nanoparticles were deposited by electrodeposition. A 1.00mM H2PtCl6 and 0.1M H2SO4 solution was prepared as an electrodeposition solution, and nitrogen was bubbled to remove oxygen for 20 minutes. A titanium mesh with a CdSe quantum dot layer prepared in step 3 was used as a working electrode, a platinum sheet was used as a counter electrode, and a saturated Ag / AgCl reference electrode was inserted. After stirring at 500 rpm, a constant potential of -0.200V was set on the electrochemical workstation. The open circuit potential was stabilized for 10 seconds, and then deposition was started. The current density was maintained at -1.85±0.05 mA / cm². After 60 seconds, the titanium mesh was taken out, vertically immersed in an ultrapure water tank for ultrasonic cleaning for 5 seconds (power 100W), and finally dried by blowing with high-purity nitrogen. A self-luminous quantum dot photoelectric synergistic catalytic oxidation electrode was obtained.Figure 1 5. The electrochemical reactor was carried out in the dark, the anode was the self-luminous quantum dot photoelectric synergistic catalytic oxidation electrode of step 4, the cathode was carbon paper (5 cm x 5 cm), the electrolyte was an aqueous solution containing 0.1 M Na2SO4 and 5 mM PBS, the parameters were set as peak voltage 5.00 V and frequency 15.00 kHz; 10.0 mg / L ciprofloxacin was used as the degradation object, and the results are shown in Figure 2 , the results show that the degradation rate can reach 99.2% within 1 h.

[0013] Example 2: Real-time detection of nitrite (NO2 - ) in the environment by using the self-luminous photoelectric synergistic catalytic electrode In this example, ITO glass substrate was used as the substrate, cobalt tetracarboxy phthalocyanine (CoPc-COOH) was used as the hole transport layer material, and nitrogen and sulfur co-doped graphene quantum dots (N, S-GQDs) were used as the quantum dot material. Cerium-doped tungsten oxide nanomaterial (WO x :Ce) was used as the catalytic material.

[0014] 1. Substrate layer treatment: ITO glass substrate (thickness 1 mm, square resistance 15 Ω / sq) was sequentially ultrasonically cleaned with acetone and isopropanol for 15 minutes, and then dried with nitrogen and treated with ultraviolet ozone for 20 minutes. 2. Hole transport layer preparation and deposition CoPc-COOH synthesis: 15 g of 1,2,4-benzene tricarboxylic anhydride, 30 g of urea, 7 g of cobalt chloride hexahydrate, and 0.24 g of molybdate ammonium tetrahydrate were sequentially added to a mortar and ground for about 10 minutes until they were crushed. Then, the powder was transferred to a flask, heated to 250°C and kept at a constant temperature for 8 hours. The resulting black product was soaked in HCl (300 mL, 1.0 M) for 14 hours and washed several times with deionized water until the pH was close to 7. Then, the product was transferred to a flask containing 1.0 M NaOH solution (300 mL), boiled for 0.5 hours, and dried in a 30°C vacuum oven for 14 hours after centrifugation. The dried product was transferred to a 300 mL flask containing 2 M NaOH in a saturated NaCl solution, and the mixture was heated to 100°C under reflux conditions for 8 hours. After cooling, it was poured into deionized water, filtered, and the filtrate was adjusted to pH 1.5 with 1.0 M HCl. The product was allowed to precipitate for 14 hours, washed with methanol / water alternately until neutral, and dried at 60°C under vacuum to obtain purple CoPc-COOH.

[0015] Film formation: CoPc-COOH was dissolved in anhydrous DMF (concentration 3 mg / mL), filtered through a 0.22 μm PTFE filter, and a film was formed on the ITO surface by spin coating. The hole transport layer was formed by annealing at 150°C for 30 minutes in a nitrogen atmosphere.​ 3. Constructing a self-luminescent quantum dot layer Synthesis of graphene oxide (GO): 2 g of graphite and 1 g of NaNO3 were added to a 250 mL flask in an ice bath, 50 mL of concentrated H2SO4 was slowly added (maintain ≤5°C), 7 g of KMnO4 was added in batches after stirring for 30 minutes in a stirrer (control temperature ≤20°C), and the reaction was moved to a 35°C water bath for 2 hours; 55 mL of ice water and 7 mL of 30% H2SO4 were added to terminate the reaction, and after filtration, the suspension was washed with 3% HCl, and the suspension was left to stand for 7 days, and dried at 40°C to obtain GO.

[0016] Synthesis of N, S-GQDs: 100 mg of GO was dissolved in 100 mL of water, ultrasonic for 1 hour to form a suspension, 100 mL of hydrazine hydrate was added, and rGO was obtained after refluxing at 100°C for 3 hours. 50 mg of rGO was added to mixed acid (V concentrated H2SO4:V concentrated HNO3=1:3), ultrasonic at 45°C for 6 hours, and after dilution, it was filtered through a 0.22 μm membrane, the solid was dispersed and dissolved in 40 mL of water, and the pH was adjusted to 8 with 1M NaOH; it was transferred to an autoclave, and reacted at 200°C for 10 hours to obtain N, S-GQDs.

[0017] N, S-GQDs were dissolved in 6 mg / mL of chlorobenzene, spin-coated on the hole transport layer, annealed at 100°C for 10 minutes, and a uniform quantum dot layer was formed.

[0018] 4. Preparation of a catalytic material layer (WO x :Ce) 2M HCl was added dropwise to an aqueous solution containing 0.1M Na2WO4·2H2O and 5 mol% Ce(NO3)3·6H2O until the pH was 2.0, and the solution was stirred for 24 hours to obtain a light yellow sol, which was then spin-coated on the quantum dot layer at 2000 rpm using a spin-coating-calcination method, pre-baked at 120°C for 10 minutes, repeated 3 times, and then annealed in a tube furnace at 180°C for 1 hour under nitrogen, and then calcined at 450°C at a rate of 2°C / min for 2 hours to form a porous WO x :Ce catalytic layer, and a self-luminescent quantum dot photoelectric synergistic catalytic oxidation electrode was prepared; 5. Assembly of a three-electrode system: the anode was a self-luminescent quantum dot photoelectric synergistic catalytic oxidation electrode prepared as described above, the counter electrode was a platinum wire, and the reference electrode was Ag / AgCl (3M KCl) to form a three-electrode system, which was placed in a sealed electrolytic cell (containing 0.1M PBS electrolyte), and the scanning rate was 50 mV / s, and the potential range was +0.4 V to +1.2 V (vs. Ag / AgCl). A significant peak appeared at 0.88 V, and the peak height (current size) increased with increasing nitrite concentration, and the linear sweep voltammogram obtained is shown in Figure 3 .

[0019] Example 3: The self-luminous photoelectric synergistic catalytic electrode and application in photoelectric catalytic glycerol oxidation for lactic acid production In this embodiment, carbon cloth is used as the substrate layer, CuO2 nanosheet array is used as the hole transport layer, CsPbBr3-BN quantum dots and NiO are co-doped to form a multifunctional composite layer, and ZnO is coated outside; 1. Substrate treatment: carbon cloth with a thickness of 0.3 mm (1 cm 2 ) was sequentially ultrasonically cleaned in acetone, ethanol, and deionized water for 15 minutes each, then immersed in a nitric acid / water mixture (68% nitric acid: water = 1:3, V / V) and placed in a polytetrafluoroethylene hydrothermal kettle at 100°C for 6 hours of hydrothermal reaction. After washing with deionized water until the pH reached 7, the sample was vacuum dried at 80°C for 2 hours; 2. In-situ growth of CuO2 nanosheet array Electrodeposition was performed using an electrolyte containing 3 g / L copper sulfate pentahydrate and 80 g / L polyethylene glycol (PEG-2000) with a pH adjusted to 9.0 using 0.1 mol / L NaOH solution. Carbon cloth was used as the working electrode, a graphite rod as the counter electrode, and a saturated calomel electrode as the reference electrode. A constant voltage of -1.2 V was applied for 30 minutes in a 60°C water bath with continuous stirring under nitrogen protection. After electrodeposition, the sample was rinsed with deionized water to remove residual electrolyte, then placed in a tube furnace and heated to 400°C at a rate of 2°C / min under an oxygen atmosphere. The sample was held at 400°C for 1.5 hours. After cooling to room temperature, a hole transport layer of CuO nanosheet array was formed on the carbon cloth; 3. Synthesis of CsPbBr3-BN quantum dots Cs2CO3 (0.45 mmol), dodecylbenzenesulfonic acid (DBSA) (3.6 mmol), and 10 mL of octadecene (ODE) were stirred under argon at 150°C for 30 minutes until transparent, obtaining a Cs-DBSA precursor solution. Separately, 0.14 g of PbBr2 was dissolved in a mixture of 10 mL of ODE, 1 mL of oleic acid (OA), and 1 mL of oleylamine (OAm). After dissolving at 130°C, the temperature was increased to 165°C, and 1.6 mL of the Cs-DBSA precursor solution was quickly injected. After 20 seconds of reaction, the mixture was quenched in an ice bath, washed with methyl acetate, and centrifuged to obtain CsPbBr3 quantum dots. The CsPbBr3 quantum dots and BN nanosheets were dispersed in a 10 mg / mL toluene solution at a mass ratio of 1:3, shielded from light, and magnetically stirred for 24 hours. After centrifugation and drying, CsPbBr3-BN composite powder was obtained; 4. In-situ integration of quantum dots / NiO co-doped layer The acetylacetone nickel (Ni(acac)2) is dissolved in anhydrous ethanol to prepare a Ni(acac)2 solution with a concentration of 0.05 mol / L. The CsPbBr3-BN powder is mixed with the Ni(acac)2 solution at a mass ratio of 1:10. The mixture is spin-coated on the hole transport layer. After spin-coating at 1000 rpm for 30 s and spin-coating again at 3000 rpm for 60 s, the sample is annealed on a hot plate at 80°C for 10 minutes. The spin-coating process is repeated three times, and the sample is annealed in nitrogen at 150°C for 1 hour to form a quantum dot catalytic material co-doped layer. 5. A zinc oxide electron blocking layer is constructed on the quantum dot / NiO co-doped layer using atomic layer deposition (ALD) technology The ALD reaction cavity is kept at a constant temperature of 150°C, and the substrate is kept rotating at a constant speed. Diethyl zinc (DEZ) is used as the zinc source, and a pulse-sweep cycle process is adopted. First, 0.1 seconds of DEZ vapor is injected into the cavity, followed by 15 seconds of high-purity nitrogen gas purging. Then, 0.1 seconds of deionized water vapor is injected, and finally, nitrogen gas is purged again for 15 seconds. This cycle is repeated 30 times to form a ZnO thin film. After completing the ALD deposition, the electrode is vertically immersed in a 5mM 4-mercapto pyridine ethanol solution, and placed in a dark environment for 20 minutes. After taking it out, it is washed with ultrapure ethanol three times, dried with nitrogen flow, and a self-luminescent quantum dot photoelectric synergistic catalytic oxidation electrode is prepared. 6. Electrode assembly: the anode uses the self-luminescent quantum dot photoelectric synergistic catalytic oxidation electrode prepared in step 5 above, the cathode uses a Pt sheet (1 cm 2 ), the electrolyte is a water solution containing 0.5 M Na2SO4+0.1 M glycerol+0.01 M NaOH (pH=10.0), a bias voltage of 1.5 V is applied, and the temperature is maintained at 60°C. It is applied to the photoelectrocatalytic glycerol oxidation to produce lactic acid. The glycerol conversion rate can reach up to 90.2% within 5 hours. The results are shown in the attached Figure 4 .

Claims

1. A self-emissive quantum dot photoelectrochemical co-catalytic oxidation electrode, characterized in that: From bottom to top, it consists of a substrate, a hole transport layer, a quantum dot layer, and a catalytic material layer; or from bottom to top, it consists of a substrate, a hole transport layer, a quantum dot catalytic material co-doped layer, and an electron blocking layer. The hole transport layer material is one of TiO2 nanotube array, cobalt tetracarboxylated phthalocyanine, or CuO nanosheet array. The quantum dot layer material is one of CdSe quantum dots, nitrogen-sulfur co-doped graphene quantum dots, or a composite of CsPbBr3 quantum dots and boron nitride. The material in the catalytic material layer is one of platinum nanoparticles, cerium-doped tungsten oxide nanomaterials, or nickel oxide. The electron blocking layer is made of zinc oxide.

2. The self-emissive quantum dot photoelectrochemical synergistic catalytic oxidation electrode according to claim 1, characterized in that: The substrate is one of carbon cloth, titanium mesh, or ITO glass.

3. The application of the self-luminous quantum dot photoelectrochemical synergistic catalytic oxidation electrode as described in claim 1 in wastewater and waste gas treatment, electrochemical synthesis, and electrochemical detection.

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