Universal base material photocatalytic electron-proton migration channel material as well as preparation and application methods thereof

Abstract

The invention belongs to the technical field of photocatalysis and new energy materials, and particularly relates to a universal base material photocatalysis electron-proton migration channel material and a preparation and application method thereof. The material comprises a conductive functional base material, a proton migration channel layer and a photocatalytic heterojunction layer which are stacked in sequence, an electron transmission path and a proton channel capable of being continuously conducted are introduced to the surface of the conductive functional base material, so that directional migration of photo-induced electrons to the base material and migration of protons along a water film or the proton migration channel layer are achieved, and the photocatalytic performance of the material is improved. And a reduction reaction is carried out on a cathode interface. The material system can use broad-spectrum base materials such as aluminum, titanium, stainless steel, PI, FTO glass and a carbon fiber composite material, and different photocatalytic applications can be realized through different construction parameters. The system disclosed by the invention has the advantages of high photon-generated carrier separation efficiency, adjustable interface energy band, extensibility to large-area coating and the like, and is a general bottom layer technology which can be used for photocatalytic hydrogen production, VOC (Volatile Organic Compound) degradation, gas purification and surface self-cleaning.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photocatalysis and new energy materials, and particularly relates to a general substrate photocatalytic electron-proton migration channel material and a preparation and application method thereof. BACKGROUND

[0002] Titanium dioxide (TiO2) is widely used in the field of photocatalytic water splitting to produce hydrogen due to its good chemical stability, low price, and non-toxicity. However, TiO2 has a wide band gap (about 3.2 eV) and mainly responds to ultraviolet light, which accounts for only about 4% of sunlight. In addition, the photogenerated carrier recombination rate is fast, resulting in low photocatalytic efficiency.

[0003] Graphitic carbon nitride (g-C3N4) is a non-metallic visible light photocatalytic material with a band gap of about 2.7 eV, which can absorb part of the visible light and has a reduction hydrogen evolution potential. However, its electrical conductivity is poor, the specific surface area is limited, and it is prone to aggregation. When used alone, the hydrogen production efficiency is limited, and there are problems such as photo corrosion, poor adhesion, and difficulty in stable loading on the surface of metal substrates.

[0004] Previous studies have shown that the combination of TiO2 and g-C3N4 to form a heterojunction structure can enhance visible light absorption and improve the separation efficiency of photogenerated electrons and holes. However, there is still a lack of stable electron-proton channel design, which limits its application. SUMMARY

[0005] In order to overcome the shortcomings of the prior art, the present application provides a general substrate photocatalytic electron-proton migration channel material and a preparation and application method thereof, which has dual electron and proton migration channels, realizes efficient separation and recombination control of photogenerated carriers, and improves the photocatalytic reaction rate and stability.

[0006] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows: The first aspect of the present application provides a general substrate photocatalytic electron-proton migration channel material, and a structural schematic diagram is shown as Figure 1 The conductive functional substrate, the proton migration channel layer, and the photocatalytic heterojunction layer are sequentially stacked. Electrons are guided from the photocatalytic heterojunction layer to the substrate, and protons move along the proton migration channel layer during the photocatalytic reaction and undergo reduction reaction at the cathode interface. The proton migration channel layer is at least one of a TiO2 layer containing oxygen vacancies (TiO 2-x ), a sulfonated polyether ether ketone membrane (SPEEK), and a phosphoric acid doped polybenzimidazole membrane (PBI-H3PO4), which is used to conduct protons during the photocatalytic reaction. The photocatalytic heterojunction layer is composed of TiO2 and g-C3N4, forming a type II heterojunction or a Z-Scheme heterojunction, which realizes the separation of photogenerated electrons and holes.

[0007] Further, the conductive functional substrate is any one of aluminum, titanium, stainless steel, magnesium alloy, FTO glass, ITO glass, polyimide, polyether ether ketone, carbon fiber composite material.

[0008] Further, the thickness of the proton migration channel layer is 20 nm-10 µm, and the proton conductivity is ≥1×10 -4 S / cm.

[0009] Further, in the photocatalytic heterojunction layer, the g-C3N4 accounts for 1-30 wt%, and the TiO2 is anatase phase or anatase / rutile composite phase.

[0010] The second aspect of the present application provides a preparation method of the universal substrate photocatalytic electron-proton migration channel material, which comprises the following steps: (1) Pretreating the surface of the conductive functional substrate to introduce hydroxyl, amino or carboxyl functional groups; (2) Constructing a proton migration channel layer on the surface of the pretreated conductive functional substrate; (3) Forming a photocatalytic heterojunction layer by film forming and annealing on the surface of the proton migration channel layer.

[0011] Further, the method for film forming and annealing of the photocatalytic heterojunction layer is: Step X1: heat polymerization of melamine, urea or dicyanediamine to obtain g-C3N4 powder; Step X2: adding the g-C3N4 powder into TiO2 hydrosol to form a composite solution by ultrasonic / high-speed shearing dispersion; Step X3: film forming by dip coating, spray coating, spin coating or blade coating; Step X4: annealing and solidification to form a heterojunction interface.

[0012] Further, in step X1, the temperature of the heat polymerization is 500-580 ℃.

[0013] Further, in step X4, the temperature of the annealing is 180-300 ℃.

[0014] The third aspect of the present application provides an application of the universal substrate photocatalytic electron-proton migration channel material in photocatalytic reaction, which includes visible light decomposition of water to produce hydrogen, photocatalytic degradation of VOC, CO2 photo-reduction to methane / methanol, air purification and self-cleaning functional surface.

[0015] Further, the method for visible light decomposition of water to produce hydrogen comprises the following steps: Step Y1: irradiating the photocatalytic heterojunction layer under air humidity ≥ 20% or liquid water environment; Step Y2: photo-generated electrons flow along the photocatalytic heterojunction layer to the conductive functional substrate and are collected by the conductive functional substrate; Step Y3: protons migrate along the proton migration channel layer to the cathode interface; Step Y4: 2H + + 2e - → H2 reaction to generate hydrogen gas.

[0016] The mechanism of the general substrate photocatalytic electron-proton migration channel material of the application is as follows: 1. Electron / hole separation and energy band matching When TiO2 (band gap ≈ 3.2 eV) and g-C3N4 (band gap ≈ 2.7 eV) form a type II heterojunction, the electrons e - of g-C3N4 are injected into the conduction band CB of TiO2, and protons h + and holes are left in the valence band VB of g-C3N4, so the separation efficiency of electrons and holes is high and the lifetime of photo-generated electrons is improved, which is suitable for organic matter degradation and formaldehyde decomposition (strong oxidation end).

[0017] Z-Scheme (direct or mediated Z-type electron transfer): retaining the strong reducing potential of g-C3N4 and the strong oxidizing potential of TiO2, suitable for water decomposition / CO2 reduction (strong reduction end). By constructing a quasi-Z-Scheme channel through interface defects / heterophase crystal surfaces and conductive carbon dots / metal nanodots (trace amounts), the electron reduction potential and lifetime can be improved without introducing an external power source.

[0018] 2. Proton (H + ) migration and solid-state channel Inorganic proton channel: oxygen vacancy-containing TiO2 (TiO 2-x ) can realize near-surface proton migration through intermediates.

[0019] Polymer proton membrane: sulfonic acid / phosphoric acid sites such as SPEEK, PBI-H3PO4 provide a continuous proton channel (10 -4 -10 -2 S·cm -1 in the wet state).

[0020] H + and e - only occur reduction after convergence in the cathode region, not in the channel.

[0021] 3. Spatial and temporal separation of electron migration and reaction sites Electron path: g-C3N4 → TiO2 → conductive functional substrate.

[0022] Proton path: water -> photocatalytic heterojunction layer surface -> proton migration channel layer -> cathode reaction interface.

[0023] Reaction occurrence location: 2H only occurs at the cathode end (conductive layer / conductive functional substrate adjacent interface) + + 2e - -> H2.

[0024] Since electrons migrate in the solid and protons migrate in the water film / channel, the two are not prone to random recombination during migration; through the built-in electric field (oxygen vacancy gradient / heterojunction; conductive layer work function matching; film thickness control), the intermediate recombination can be further inhibited, and the lifetime can be improved.

[0025] 4. Gas partition and safety Oxygen production area: upper layer (close to the g-C3N4 interface) - hole oxidation of H2O to generate O2.

[0026] Hydrogen production area: lower layer (close to the conductive / cathode interface) - electron + proton to generate H2.

[0027] Export: H2 is exported through the cathode interface; O2 is released from the anode interface -> physical partition to prevent mixing.

[0028] The "single-substrate multi-functional partition coating" path is materially realizable, and is supported by sufficient band gap / carrier dynamics and solid-state proton conduction mechanism, and can operate under the condition of "only sunlight + water", without relying on an external power source.

[0029] Compared with the prior art, the present application has the following advantages: The present application provides a universal substrate photocatalytic electron-proton migration channel material and a preparation and application method thereof. The material described in the present application comprises a conductive functional substrate, a proton migration channel layer and a photocatalytic heterojunction layer which are stacked in sequence, by introducing an electron transport path and a continuously conductive proton channel on the surface of the conductive functional substrate, the photo-generated electrons are directed to migrate to the conductive functional substrate, the protons migrate along the water film or the proton migration channel layer, and the reduction reaction occurs at the cathode interface. The material system of the present application can use a wide range of substrates such as aluminum, titanium, stainless steel, PI, FTO glass, carbon fiber composite materials, and can realize different photocatalytic applications through different construction parameters. The system of the present application has the advantages of high photo-generated carrier separation efficiency, adjustable interface energy band, and expandable to large-area coating, and is a universal bottom technology which can be used for photocatalytic hydrogen production, VOC degradation, gas purification and self-cleaning surface.

[0030] Specifically, the present application has the following advantages: (1) The photo-generated electron-proton separation efficiency of the photocatalytic electron-proton migration channel material of the present application is 2-3 times higher than that of single-layer TiO2. (2) The hydrogen production rate of the photocatalytic electron-proton migration channel material of the present invention is 4-6 times higher than that of monolayer TiO2; (3) The photocatalytic electron-proton migration channel material of the present invention is compatible with a variety of substrates and has significantly improved adhesion; (4) The photocatalytic electron-proton migration channel material of the present invention can be extended to photocatalytic systems such as CO2 reduction and VOC degradation. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the general-purpose substrate photocatalytic electron-proton migration channel material of the present invention. Detailed Implementation

[0032] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0033] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0034] The raw material types and manufacturers used in the following examples are shown in Table 1.

[0035] Table 1 The relevant test methods in the following embodiments are as follows: 1. Hydrogen production rate rH2 (unit: μmol·m) -2 ·h -1 The testing method is as follows: Light source: AM 1.5G, 100 mW·cm -2 (Calibrated by an irradiometer), sample distance from lamp surface 15 cm; test temperature 25 ± 1 °C. Liquid water / water vapor: sealed quartz reactor, bottom containing 2 mL of deionized water; gas phase volume V_gas = 120 mL.

[0036] Sampling: Initial evacuation (or N2 filling, recording initial pressure / volume), followed by illumination to steady state, sampling every 10 minutes for a total of 120 minutes.

[0037] Detection: GC-TCD (N2 carrier gas), external standard calibration (H2 100, 500, 1000, 2000 ppm). Effective light-receiving area A = 25 cm². 2 (5 cm × 5 cm). The hydrogen concentration C was obtained from GC.H2 (t) (ppm), the algorithm for the conversion of the number of moles is as follows: The rate is obtained from the slope dn / dt in the linear steady state region.

[0038] Area normalization: Apparent quantum efficiency AQE@420 nm (%): 420 ± 10 nm monochromatic light, photon flux measured: wherein, .

[0039] 2. The CO2 photoreduction performance test method is as follows: Gas-solid phase reaction, photocatalytic sheet area: 4 cm 2 , quartz reactor volume: 80 mL, CO2 saturated water vapor environment (maintain proton source), pressure: 101 kPa, light source: 300 W xenon lamp, 420 nm cut-off filter (remove ultraviolet light), incident light intensity: 80 mW / cm 2 (visible light).

[0040] The reactor is vacuumed to 0.01 MPa, about 80 mL of dry CO2 is introduced, 0.5 mL of deionized water (provides H + ) is added, the reaction is closed, and the light reaction is carried out for 6 h, and sampling is carried out once every 30 min (100 μL), and GC-TCD / FID is used to quantitatively determine CH4, CO, CH3OH and H2.

[0041] Example 1: Preparation of aluminum substrate / TiO 2-x / SPEEK / TiO2@g-C3N4 Z-Scheme heterojunction photocatalytic electron-proton migration channel material and its application in the photodecomposition of water to produce hydrogen (1) Substrate treatment 6061 aluminum sheet (20 × 20 × 0.5 mm) is selected, polished with 400 mesh sandpaper for 1 minute, then alkaline washed with 3 wt% NaOH solution at 55 °C for 2 minutes, and then neutralized with 1 wt% HNO3 for 30 seconds, so that the surface of the aluminum sheet is uniform matte.

[0042] (2) Preparation of TiO 2-x Oxygen vacancy layer (electron channel) Spray 2 wt% TiO2 sol on the surface of the treated aluminum sheet (nozzle diameter 0.3 mm), dry at 80 °C for 5 minutes, then anneal at 300 °C for 1 hour in air atmosphere, obtain a TiO2 layer with a thickness of about 150-200 nm, treat in argon (95%) + hydrogen (5%) mixed atmosphere at 350 °C for 30 minutes to construct oxygen vacancies, TiO2 becomes blue tone TiO 2-x (electron concentration is improved, conductivity ~ 10 -5 S / cm).

[0043] (3) Constructing SPEEK proton channel layer Prepare a 12 wt% SPEEK solution using SPEEK resin and NMP solvent, stir at 60 °C for 2 hours, then spin coat on the surface of the TiO 2-x oxygen vacancy-containing layer (800 rpm x 10 s, 3000 rpm x 40 s), dry at 80 °C for 1 hour under vacuum 0.09 MPa, obtain a SPEEK proton channel layer with a film thickness of ~700 nm, its wet-state proton conductivity is 3.1 x 10 -3 S·cm -1 .

[0044] (4) Preparation of g-C3N4 powder Take 10 g of melamine and place it in a crucible with a lid, heat to 550 °C (5 °C / min) in a muffle furnace and keep for 3 hours, obtain yellow fluffy g-C3N4 (particle size 0.5-2 μm).

[0045] (5) Preparation of TiO2@g-C3N4 Z-Scheme heterojunction solution Add g-C3N4 powder to TiO2 sol (2 wt%) to make the concentration of g-C3N4 powder 15 wt% (relative to TiO2 solid content), 100 W ultrasonic for 30 min, then high shear at 3000 rpm for 5 min, obtain a stable yellow composite solution.

[0046] (6) Film formation and interface solidification Dip coat the SPEEK proton channel layer obtained in step (3) in the TiO2@g-C3N4 Z-Scheme heterojunction solution for 2 times, pulling speed is 2 mm / s, then dry at room temperature for 10 min, solidify at 250 °C for 1 hour in air atmosphere, finally obtain a photocatalytic layer with a thickness of ~800-1200 nm.

[0047] (7) Verification of technical effect Hydrogen production rate test: the test light source is AM 1.5G (100 mW / cm2 ), under water vapor condition, the test area is 4 cm 2 , the test time is 2 h, the hydrogen production rate of the photocatalytic material of the present embodiment is 58 μmol·h -1 ·cm -2 .

[0048] Example 2: Preparation of FTO glass substrate / PBI-H3PO4 / TiO2@g-C3N4 Z-Scheme heterojunction photocatalytic electron-proton migration channel material and application of CO2 photoreduction to prepare CH4 / CH3OH (1) Substrate cleaning and activation treatment The FTO glass is cut into a size of 20 mm × 20 mm, and then sequentially subjected to ultrasonic treatment with deionized water for 10 min, ultrasonic treatment with ethanol for 10 min, ultrasonic treatment with acetone for 10 min, and nitrogen blowing to dry, followed by plasma surface treatment (power: 100 W, time: 2 min) to form -OH groups on the surface and improve the adhesion of the subsequent PBI film.

[0049] (2) Preparation of PBI-H3PO4 proton migration channel layer PBI resin and solvent DMAc are prepared into a 15 wt% PBI solution, stirred at 90 °C for 4 hours to form a uniform light yellow solution, which is coated on the treated FTO glass to form a film (knife gap: 50 μm, coating speed: 30 mm / s), to obtain a wet film thickness of about 50-60 μm, dried at 80 °C for 1 h under vacuum and at 120 °C for 1 h, then the dry film is immersed in an 85 wt% H3PO4 solution, immersed at 70 °C for 4 h, then taken out and rinsed with deionized water for 10 s, and dried at 60 °C under vacuum for 2 h to obtain a PBI-H3PO4 proton migration channel layer. Through proton conductivity test, the σ of the wet state (RH 70%, 25 °C) is measured to be 4.5 × 10 -3 S / cm, the film thickness is about 1.5-2.0 μm, and the PBI-H3PO4 proton migration channel layer is a key structure in the CO2 reduction system because: CO2 reduction requires the participation of protons (H + ), the solid-state proton film ensures directional proton migration, and the coupling of electrons and protons at the cathode interface improves selectivity (towards methane or methanol).

[0050] (3) Preparation of g-C3N4 powder Melamine 10 g is placed in a muffle furnace and heated to 550 °C (temperature rise 5 °C / min), and kept for 3 h to obtain yellow lamellar g-C3N4, which is ground and passed through a 300 mesh sieve with a particle size of ~1-2 μm.

[0051] (4) Preparation of TiO2@g-C3N4 Z-Scheme heterojunction coating solution Mixing ratio (optimized after experiment): TiO2 hydrosol (solid content: 2 wt%) was mixed with g-C3N4 powder, and the mass ratio of g-C3N4:TiO2 was controlled at 20:80 (wt%). After 200 W ultrasonic treatment for 30 min, high-shear dispersion was performed at 4000 rpm for 5 min, and a light yellow stable composite coating solution was obtained.

[0052] (5) Film forming step The composite coating solution was spin-coated (800 rpm x 10 s, 2500 rpm x 40 s) on the surface of the PBI-H3PO4 proton migration channel layer prepared in step (2), and was annealed at 220 °C for 1 h in an air atmosphere for curing. The temperature of 220 °C can ensure that the structure of g-C3N4 is not significantly damaged, and can also promote interfacial bonding (Ti-O-C bond). The final photocatalytic layer has a thickness of about 700-900 nm.

[0053] (6) Verification of technical effects After verification, the product and yield in this embodiment are shown in Table 2.

[0054] Table 2 Among them, the total carbon-based product selectivity is > 97%, and the non-selective product (CO / H2) is significantly inhibited.

[0055] Example 3: Preparation of carbon fiber composite (CFRP) substrate / TiO 2-x / SPEEK-PBI / TiO2@g-C3N4 heterojunction photocatalytic electron-proton migration channel material and its application in flexible and rollable air purification film for rapid degradation of VOC (formaldehyde, benzene series) and anti-fouling self-cleaning (1) CFRP substrate treatment (key step) The surface of carbon fiber is inert and smooth, and needs to be activated to enhance the adhesion. The surface resin is lightly sanded with 2000 mesh sandpaper (10-15 seconds) to remove the surface float glue, and then plasma activation is performed (power: 150 W, time: 90 s) to form functional groups such as C-OH, C=O, COOH, etc., to improve hydrophilicity and coating adhesion. After surface energy test (water drop method), the contact angle is optimized from 94° to 47°, indicating that the activation is successful.

[0056] (2) Preparation of TiO 2-x Electron migration channel layer (flexible and bendable) Spray 2 wt% TiO2 sol on the surface of the treated CFRP substrate (air pressure: 0.15 MPa, spray distance: 15 cm), spray back and forth 2 times, pre-dry at 80 °C for 10 min, then anneal at 250 °C for 40 min to solidify (CFRP thermal deformation temperature ≈ 260 °C, this temperature is in the safe range), build oxygen vacancies (local reduction) under 95% Ar + 5% H2 atmosphere at 230 °C for 20 min, the obtained TiO 2-x The film is light blue in color, with a thickness of about 100-150 nm, and does not crack under bending conditions.

[0057] (3) Preparation of SPEEK-PBI composite proton migration channel layer The composite layer is used to improve flexibility, bending resistance and proton conductivity. A 10 wt% SPEEK solution is prepared using SPEEK resin and solvent NMP, a 5 wt% PBI solution is prepared using PBI resin and nmp solvent, and the two are mixed in a volume ratio of 4:1, stirred at 60 °C for 2 hours to obtain a composite solution. The purpose is to form an interpenetrating network (IPN) to enhance mechanical toughness and proton conduction stability. The composite solution is coated on the TiO 2-x The surface of the electron migration channel layer is spin-coated into a film (1500 rpm x 45 s), dried at 70 °C for 1 h, and then vacuum dried at 100 °C for 1 h, obtaining a dry film with a thickness of 0.9-1.2 μm. Then immerse in 50 wt% H3PO4 solution, immerse at 60 °C for 1 h, this condition ensures both proton channel and flexibility. Test results show that the proton conductivity of the SPEEK-PBI composite proton migration channel layer is 2.8 x 10 -3 S / cm, the conductivity decreases by < 6% after 500 bending cycles, and the performance is stable.

[0058] (4) Preparation of TiO2@g-C3N4 photocatalytic heterojunction layer Take 10 g of melamine and place it in a muffle furnace, heat at 530 °C (5 °C / min) for 2 h, obtain sheet-like g-C3N4 (thickness about 1 μm), add g-C3N4 to TiO2 aqueous sol (2 wt%), g-C3N4 addition amount is 10-15 wt% (relative to TiO2 solid content), 200 W ultrasonic for 20 min, the solution is light yellow and uniform colloid. Then scrape the film on the surface of the SPEEK-PBI composite proton migration channel layer prepared in step (3) (scraping gap: 30 μm), then dry at room temperature for 20 min, low temperature curing at 200 °C for 1 hour in air atmosphere, this temperature ensures that the CFRP does not warp and is not damaged, the final film thickness is 600-800 nm.

[0059] (5) Technical effect verification Flexible bending performance test: bending angle 0-180° back and forth cycle, bending radius: 5 mm, cycle number: 1000 times, test results are shown in Table 3. The test results show that the material has excellent flexibility and adhesion.

[0060] Table 3 Evaluation index Before bending After bending Resistance change Reference ↑ 4.8% Photocatalytic efficiency (formaldehyde degradation) 100% reference Retained 92% Film surface cracks None No visible cracks Photocatalytic air purification performance evaluation: the initial concentration of formaldehyde is 1 ppm (standard room air simulation), the light source is LED (410-450 nm), visible light, the flow rate of the flow reactor is 200 mL / min, the test area is 10 cm 2 , the temperature is 25°C, and the test results are: the formaldehyde degradation rate is 98.3% after irradiation for 120 min.

[0061] Stain self-cleaning test: 10 μL of methyl orange solution (1×10 -4 M) is added on the surface of the material, 420 nm LED light irradiation for 40 min, and the basic color fades, the surface is washed with clean water and returns to clean without residual dye. It shows that the material has photocatalytic self-cleaning ability.

[0062] The embodiments of the application are described in detail above, but the application is not limited to the described embodiments. For those skilled in the art, various changes, modifications, replacements and variations of the embodiments can be made without departing from the principles and spirits of the application, and still fall within the protection scope of the application.

Claims

1. A general-purpose substrate photocatalytic electron-proton migration channel material, characterized by, The photocatalytic heterojunction layer is formed by TiO2 and g-C3N4, forming a type II heterojunction or a Z-Scheme heterojunction, realizing the separation of photo-generated electrons and holes. The conductive functional substrate is any one of aluminum, titanium, stainless steel, magnesium alloy, FTO glass, ITO glass, polyimide, polyether ether ketone, and carbon fiber composite material. The photocatalytic heterojunction layer contains 1-30 wt% of g-C3N4 and TiO2 in an anatase phase or an anatase / rutile composite phase.

2. The universal substrate photocatalytic electron-proton migration channel material according to claim 1, characterized in that, The preparation method comprises the following steps:

3. The universal substrate photocatalytic electron-proton migration channel material according to claim 1, characterized in that, The proton-conducting channel layer has a thickness of 20 nm to 10 µm and a proton conductivity of ≥ 1 × 10 -4 S / cm.

4. The universal substrate photocatalytic electron-proton migration channel material according to claim 1, characterized in that, (1) Pretreating the surface of the conductive functional substrate to introduce hydroxyl, amino, or carboxyl functional groups; 5. A method for preparing a universal substrate photocatalytic electron-proton migration channel material according to any one of claims 1-4, characterized in that, (2) Constructing a proton migration channel layer on the surface of the pretreated conductive functional substrate; (3) Forming a photocatalytic heterojunction layer on the surface of the proton migration channel layer and annealing. The method for forming and annealing the photocatalytic heterojunction layer comprises the following steps: Step X1: Thermal polymerization of melamine, urea, or dicyandiamide to obtain g-C3N4 powder; 6. The method of claim 5, wherein the method is characterized by: Step X2: Adding the g-C3N4 powder to TiO2 hydrosol, and dispersing by ultrasonic / high-speed shearing to form a composite solution; Step X3: Film formation by dip coating, spray coating, spin coating, or blade coating; Step X4: Annealing and solidification to form a heterojunction interface. In step X1, the thermal polymerization temperature is 500-580 ℃. In step X4, the annealing temperature is 180-300 ℃.

7. The method of claim 6, wherein the method is characterized by: The photocatalytic reaction includes visible light water splitting for hydrogen production, photocatalytic degradation of VOC, CO2 photo-reduction to methane / methanol, air purification, and self-cleaning functional surface.

8. The method of claim 6, wherein the method is characterized by: The method for visible light water splitting for hydrogen production comprises the following steps:

9. Use of the universal substrate photocatalytic electron-proton migration channel material according to any one of claims 1-4 in a photocatalytic reaction, characterized in that, Step Y1: Irradiating the photocatalytic heterojunction layer under an air humidity of ≥20% or in a liquid water environment; 10. Use of the general substrate photocatalytic electron-proton migration channel material according to claim 9 in a photocatalytic reaction, characterized in that, Step Y2: Photo-generated electrons flow along the photocatalytic heterojunction layer to the conductive functional substrate and are collected by the conductive functional substrate; Step Y3: Protons migrate along the proton migration channel layer to the cathode interface; ​ ​ Step Y4: 2H at the cathode end + + 2e - → H2 reaction to produce hydrogen gas.

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