Melamine-mediated pomof-derived molybdenum carbide supported copper nanoparticle catalysts, methods of making and using the same

Abstract

The application provides a melamine-mediated POMOF-derived molybdenum carbide supported copper nanoparticle catalyst and a preparation method and application thereof, and belongs to the field of photoelectric catalysis environmental pollution treatment and new energy (hydrogen production) cooperation. The preparation method of the catalyst is as follows: a methanol solution of trimesic acid, a methanol mixed solution of copper acetate monohydrate and hydrated phosphomolybdic acid, and melamine are sequentially mixed, stirred, placed, centrifuged, washed, dried and dehydrated to obtain a POMOF / melamine catalyst precursor; the POMOF / melamine catalyst precursor is pyrolyzed to obtain a melamine-mediated POMOF-derived molybdenum carbide supported copper nanoparticle catalyst; the preparation method is simple, raw materials are easy to obtain, the efficiency of antibiotic removal is high, H2 production is excellent, the applicable range of alkaline pH is wide, the electrode stability is strong and is not easily affected by water quality characteristics, is suitable for the treatment of refractory organic pollutants under complex water quality conditions, and the preparation method is simple and suitable for industrial production.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photoelectrocatalytic environmental pollution treatment and new energy (hydrogen production), in particular to a melamine-mediated POMOF-derived molybdenum carbide supported copper nanoparticle catalyst, a preparation method and application thereof. BACKGROUND

[0002] Water is an irreplaceable natural resource for the continuation and development of human society. The rapid development of industry has brought many untreated pollutants into the water environment, among which antibiotics from agricultural medicine, aquaculture, livestock and urban domestic sewage production and living processes are important sources. Although the detection value of antibiotics in various environmental media is not high (only μg / L, ng / L or even pg / L), due to their complex chemical structure, biological toxicity, environmental persistence, strong migration and biological accumulation, they are difficult to be naturally metabolized and degraded, so they will continue to accumulate, migrate and diffuse in the water environment, causing long-term pollution to the environment and potential and lasting threats to the ecological environment and human health. In view of the fact that antibiotics have been widely present in the water environment and are difficult to accurately control and completely eliminate in the short term, exploring green and efficient new technologies for deep purification of antibiotics is an important research topic to meet the needs of the national major strategy, so it is crucial to develop efficient, economical, safe and stable water purification technologies that can resist environmental interference.

[0003] In recent years, photoelectrocatalytic advanced oxidation technology (PEC-AOPs) that realizes the synchronous coupling of photocatalytic process (PC) and electrocatalytic process (EC) has shown remarkable advantages in removing refractory organic pollutants. On the one hand, compared with PC process, PEC process is a process driven by light energy and electrical energy, which contains a bias voltage to enhance the separation of photo-generated electrons and holes, realizing the synchronous coupling of PC process and EC process, which greatly improves the generation efficiency of ROS in PC process and helps the decomposition and mineralization of pollutants. On the other hand, PEC process not only solves the problem of recovery of powdered catalyst in PC process, but also reduces the cost generated by the electrolysis process driven by electricity. At the same time, in the PEC process, by taking antibiotics as an electron donor, H2 can be produced while degrading pollutants, which greatly improves the practicability of PEC process and to some extent alleviates the problem of energy shortage. The key to realizing the degradation of pollutants while efficiently producing hydrogen is the efficient separation of photo-generated electron-hole pairs, so selectively triggering the hole degradation pathway is expected to play an important role in removing antibiotic pollutants under complex water quality conditions while efficiently producing hydrogen, which highly depends on the light absorption capacity, energy band structure and electron distribution of the catalyst.

[0004] In recent years, molybdenum carbide (Mo2C) has specific catalytic activity in some chemical reactions due to its porous structure, high chemical stability, high electron conductivity, and advantages such as comparable D-orbital structure and Fermi level electronic state to noble metals (especially Pt). Meanwhile, the activity of Mo2C can be improved by introducing inexpensive transition metals (such as Fe, Co, Cu and Ni), which can ideally adjust the electronic state of Mo active centers. However, the Mo2C obtained at high temperature is inevitably prone to aggregation, which affects its catalytic performance. In order to solve this problem, it is a good solution to introduce a porous carbon-nitrogen material as a supporting framework for Mo2C to reduce its aggregation and improve its conductivity. The nitrogen-doped carbon matrix can firmly stabilize high-energy single atoms through metal-nitrogen interaction to alleviate the aggregation of metal atoms. Despite these advantages, there is still an urgent need to explore suitable precursors for the uniform hybridization of Mo and metal sources to controllably prepare optoelectronic materials with more abundant active sites, larger specific surface area and larger interface to enhance visible light absorption, slow down the recombination of photo-generated electron-hole pairs, accelerate electron transfer, optimize the electronic coordination environment, and reduce the reaction barrier. SUMMARY

[0005] Therefore, the present application aims to provide a melamine-mediated POMOF-derived molybdenum carbide supported copper nanoparticle catalyst and its preparation method and application. The obtained catalyst can effectively promote the separation of photo-generated electron-hole pairs by selectively initiating a single degradation pathway (hole), thereby enhancing the electron pair H + The reduction produces H2, thereby achieving degradation of antibiotic pollutants in complex water quality while efficiently producing H2; the preparation method is simple and has strong operability, high antibiotic removal efficiency and excellent H2 production, a wide range of suitable alkaline pH, and strong electrode stability which is not easily affected by water quality characteristics, suitable for the treatment of refractory organic pollutants under complex water quality conditions, and the preparation method is simple and suitable for industrial production.

[0006] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] In a first aspect, the present application provides a preparation method of a melamine-mediated POMOF-derived molybdenum carbide supported copper nanoparticle catalyst, comprising the following steps:

[0008] (1) mixing, stirring, standing, centrifuging, washing, drying and dehydrating methanol solutions of trimesic acid, copper acetate monohydrate and hydrated phosphomolybdic acid in sequence to obtain a POMOF / trimesine catalyst precursor;

[0009] (2) pyrolyzing the POMOF / trimesine catalyst precursor to obtain a melamine-mediated POMOF-derived molybdenum carbide supported copper nanoparticle catalyst.

[0010] In the present application, according to the Mott-Schottky heterojunction theory, the metal-semiconductor interface formed by the metal copper nanoparticles and Mo2C can change the electron transfer structure of Mo2C, and the rich interface between Cu, Mo2C and NC can also provide sufficient active sites, and the heterostructure can also promote the separation of photo-generated electron-hole pairs to further improve the utilization efficiency of holes and electrons, thereby efficiently removing antibiotic pollutants in complex water and reducing H + .

[0011] The molybdenum source of the catalyst of the present application is polyoxometalate (POM)-hydrated phosphomolybdate, which generally contains metal elements in the highest valence state and has reversible multi-electron transfer capability.

[0012] The catalyst of the present application generally utilizes the characteristic that POM is easy to disperse in MOF, and a POMOF material in which POM is coated in the cavity of MOF is prepared, which is beneficial to uniform carbonization and avoids agglomeration.

[0013] The catalyst prepared in the present application is mediated by melamine, which not only provides a nitrogen-carbon base, but also reduces divalent copper ions to copper nanoparticles and tetravalent molybdenum to divalent molybdenum, thereby increasing the redox performance of the material.

[0014] Preferably, the concentration of the methanol solution of trimesic acid in step (1) is 2%; the concentration of the methanol mixed solution of copper acetate monohydrate and hydrated phosphomolybdate is 3.8-9.7%.

[0015] Preferably, the molar ratio of trimesic acid, copper acetate monohydrate and hydrated phosphomolybdate in step (1) is 1:1:0.2.

[0016] The mass ratio of copper acetate monohydrate to melamine is 4:1.

[0017] Preferably, the stirring time in step (1) is 14h.

[0018] Further preferably, at least one of the following conditions is met in step (1):

[0019] The mixing time is 5-10min;

[0020] The standing time is 14h;

[0021] The centrifugal rate is 8000-10000r / min;

[0022] The washing solvent is methanol;

[0023] The drying temperature is 60-80℃;

[0024] The dehydration time is 12-24 h.

[0025] As preferred, the pyrolysis step in step (2) is carried out with nitrogen as the protective gas, the heating rate is 5-10℃ / min, the pyrolysis temperature is 700-900℃, and the pyrolysis holding time is 2-3 h.

[0026] In a second aspect, the present application provides a melamine-mediated POMOF-derived molybdenum carbide supported copper nanoparticle catalyst prepared by the above preparation method.

[0027] In a third aspect, the present application provides an anode of a photoelectrocatalytic reactor prepared by the above melamine-mediated POMOF-derived molybdenum carbide supported copper nanoparticle catalyst by drop coating method.

[0028] In a fourth aspect, the present application provides the use of the above melamine-mediated POMOF-derived molybdenum carbide supported copper nanoparticle catalyst in photoelectrocatalytic removal of antibiotics in wastewater while producing H2, wherein the antibiotics include one or more of tetracycline, aureomycin, doxycycline, and ciprofloxacin.

[0029] As preferred, the photoelectrocatalytic reactor is an H-type double-chamber reactor, wherein the anode is the above-prepared anode, and the cathode is a platinum sheet electrode.

[0030] As preferred, the H-type double-chamber reactor is separated by a DuPont Nafion proton membrane.

[0031] As preferred, the anode electrolyte solution in the H-type double-chamber reactor is a 0.1 mol / L sodium sulfate solution, and the cathode electrolyte is a 1.0 mol / L potassium hydroxide solution.

[0032] When removing antibiotics in wastewater, the pH value of the reaction system is 3-11, the reaction system temperature is 25-30℃, the voltage is 0.5-3.5V, and the light intensity is 2.4W / cm 2 .

[0033] As preferred, the quenching agent for removing antibiotics in wastewater includes disodium ethylenediaminetetraacetate, tert-butyl alcohol, furfuryl alcohol, and nitro blue tetrazolium.

[0034] Beneficial technical effects:

[0035] (1) According to the Mott-Schottky heterojunction theory, the present application constructs a metal-semiconductor interface formed by the combination of metal copper nanoparticles and Mo2C, which not only provides sufficient active sites, but also promotes the separation of photo-generated electron-hole pairs to further improve the utilization efficiency of holes and electrons, thereby efficiently removing antibiotic pollutants in complex water quality while reducing H + H2 in water;

[0036] The catalyst prepared by the application is derived from a POMOF, inherits the adjustable morphology and multifunctionality of the POMOF, and can expose more active sites; meanwhile, the catalyst has good dispersity and overcomes the problem of easy agglomeration of Mo2C.

[0037] (2) The catalyst is prepared by one-step calcination, and the synthesis process flow is simple; the catalyst raw material uses copper acetate monohydrate as a metal source and H3BTC as a ligand, and has the advantages of wide material source and low cost.

[0038] (3) The anode degradation chamber and the cathode reduction chamber are physically separated, so that the degradation of the anode antibiotic and the reduction of H + at the cathode are simultaneously and efficiently performed, and a catalyst capable of selectively initiating a single degradation pathway (hole) is prepared, so as to effectively promote the separation of the photo-generated electron-hole pair, enhance the reduction of H + by the electron pair, realize more than 90% removal of the antibiotic in 10-15 min, and not be easily affected by water quality characteristics, and has a wide application prospect in the treatment of antibiotic pollutants in complex water quality while producing hydrogen. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only constitute the embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of the provided drawings.

[0040] Figure 1 Figure is a graph of the removal rate of DOX in the anode degradation of the catalyst prepared in examples 1-5 in the photoelectrocatalytic system;

[0041] Figure 2 Figure is a graph of the H2 production at the cathode in the photoelectrocatalytic degradation of DOX system of the catalyst prepared in examples 1-5;

[0042] Figure 3 Figure is a graph of the removal rate of DOX in the anode degradation of the catalyst prepared in examples 2 and examples 6-8 in the photoelectrocatalytic system;

[0043] Figure 4 Figure is a graph of the H2 production at the cathode in the photoelectrocatalytic degradation of DOX system of the catalyst prepared in examples 2 and examples 6-8;

[0044] Figure 5Figure of DOX removal rate in photoelectrocatalytic system for catalyst prepared in Example 1 and Examples 9-11 at anode;

[0045] Figure 6 Figure of H2 production at cathode in photoelectrocatalytic system for catalyst prepared in Example 1 and Examples 9-11 for degradation of DOX;

[0046] Figure 7 Figure of DOX removal rate in photoelectrocatalytic system for catalyst prepared in Example 1 and Examples 12-13 at anode;

[0047] Figure 8 Figure of H2 production at cathode in photoelectrocatalytic system for catalyst prepared in Example 1 and Examples 12-13 for degradation of DOX;

[0048] Figure 9 Figure of SEM for catalyst prepared in Example 5 without calcination;

[0049] Figure 10 Figure of SEM for catalyst prepared in Example 2 without calcination;

[0050] Figure 11 Figure of SEM for catalyst prepared in Example 1 without calcination;

[0051] Figure 12 Figure of SEM for catalyst prepared in Example 1;

[0052] Figure 13 Figure of XRD for catalyst prepared in Example 1, Example 2, Example 5 and Example 5 without calcination;

[0053] Figure 14 Figure of effect of different external voltage on DOX removal rate in photoelectrocatalytic system for catalyst prepared in Example 1 at anode;

[0054] Figure 15 Figure of effect of different external voltage on H2 production at cathode in photoelectrocatalytic system for catalyst prepared in Example 1 for degradation of DOX;

[0055] Figure 16 Figure of effect of different initial pH on DOX removal rate in photoelectrocatalytic system for catalyst prepared in Example 1 at anode;

[0056] Figure 17 Figure of effect of different initial pH on H2 production at cathode in photoelectrocatalytic system for catalyst prepared in Example 1 for degradation of DOX;

[0057] Figure 18Figure of anodic degradation of different pollutants in photoelectrocatalytic system for catalyst prepared in example 1;

[0058] Figure 19 Figure of cathodic H2 production in photoelectrocatalytic degradation of different pollutants for catalyst prepared in example 1;

[0059] Figure 20 Figure of anodic degradation of DOX in photoelectrocatalytic system for catalyst prepared in example 1 after 4 cycles and calcination;

[0060] Figure 21 Figure of cathodic H2 production in photoelectrocatalytic degradation of DOX for catalyst prepared in example 1 after 4 cycles and calcination;

[0061] Figure 22 Figure of quenching experiment in photoelectrocatalytic degradation of DOX for catalyst prepared in example 1;

[0062] Figure 23 Figure of cathodic H2 production in photoelectrocatalytic degradation of DOX for catalyst prepared in example 1 at quenching. DETAILED DESCRIPTION

[0063] The present application will be described in greater detail by way of specific embodiments. These embodiments are provided to more fully describe the application and to convey the scope of the application to those skilled in the art. If not specifically mentioned, the technical means used in the embodiments are the routine means known to those skilled in the art. The test methods in the following examples are routine methods unless otherwise specified. The reagents and materials used are commercially available unless otherwise specified.

[0064] Example 1

[0065] This embodiment provides a melamine-mediated POMOF-derived molybdenum carbide supported copper nanoparticle catalyst, and the preparation steps are as follows:

[0066] 1) Under the condition of magnetic stirring, H3BTC (0.62 g, 3.0 mmol) was dissolved in methanol solution (40 ml) to form solution A, copper acetate monohydrate (0.6 g, 3.0 mmol) and hydrated phosphomolybdic acid (1.24 g, 0.6 mmol) were dissolved in methanol solution (40 ml) to form solution B, then solution A was slowly added to solution B and 0.15 g of melamine was added, and stirring was carried out at room temperature for 14 h to obtain a blue-green precipitate, which was washed with methanol and distilled water twice, and then centrifuged and collected, and dried at 60°C overnight to obtain a POMOF / melamine catalyst.

[0067] 2) The POMOF / melamine catalyst was placed in a quartz boat, which was then transferred to a tube furnace. Nitrogen was introduced into the tube furnace to remove air, and then the temperature was raised to 800°C at a rate of 5°C / min under a nitrogen atmosphere and pyrolysis was carried out for 2 h. After cooling to room temperature, the melamine-mediated POMOF-derived Cu / Mo2C / NC-5-0.25-800 catalyst was obtained.

[0068] Example 2

[0069] The preparation method of this example is the same as that of Example 1, except that no melamine is added, and Cu / MoO2-5-800 is prepared.

[0070] Example 3

[0071] The preparation method of this example is the same as that of Example 1, except that no copper acetate monohydrate and H3BTC are added, and Mo2C / NC-0.25-800 is prepared.

[0072] Example 4

[0073] The preparation method of this example is the same as that of Example 1, except that no phosphomolybdic acid hydrate is added, and Cu / Cu2O / NC-0.25-800 is prepared.

[0074] Example 5

[0075] The preparation method of this example is the same as that of Example 1, except that no phosphomolybdic acid hydrate and melamine are added, and Cu / Cu2O-800 is prepared.

[0076] Experimental Example 1

[0077] The removal rate of DOX in water and the H2 production of the products of Examples 1-5 were tested, and the testing method is as follows:

[0078] A single-chamber effective volume of 100 ml H-type double-chamber reactor was selected as the photoelectrocatalytic reactor, and the FTO working electrode prepared by drop coating method was used as the anode (effective area of 1 x 2 cm 2 ), and the foil was used as the cathode (effective area of 1 x 2 cm 2 ) to construct the PEC reactor. The anode chamber and the cathode chamber were separated by a N117 proton membrane with a diameter of 30 mm. The electrolyte solution in the anode solution was 0.1 mol / L Na2SO4 solution, and the electrolyte solution in the cathode solution was 1.0 mol / L KOH solution. The anode light source was a 250W xenon lamp with an ultraviolet filter (λ>420 nm). The initial concentration of DOX was 10 mg / L in 100 mL simulated organic wastewater, the direct current power voltage was 2.5 V, and the light intensity was 2.4 W / cm 2Without adjusting the pH of the wastewater (at this time the pH of the wastewater is 6.54), the reaction is carried out by a magnetic stirrer at 25℃, and the residual concentration of anode DOX and the cathode H2 production are measured at 1 min, 3 min, 5 min, 7 min, 10 min and 15 min, respectively, to calculate the removal rate of DOX and the amount of hydrogen production.

[0079] The calculation results are shown in Figure 1 and Figure 2 As shown, the degradation performance of Cu / MoO2 derived by adding POM is enhanced compared with Cu / Cu2O derived by Cu-MOF alone, and the hydrogen production is also improved, but the effect is not significant; in addition, the degradation performance of Cu / MoC2 / NC generated by adding melamine is further enhanced, and the hydrogen production is as high as 204.3 μmol, but the study of Cu / Cu2O / NC and MoC2 / NC derived by adding melamine to the MOF and POM materials alone shows that the addition of melamine inhibits the degradation and hydrogen production performance, which indicates that the Mott-Schottky heterojunction composed of copper nanoparticles and molybdenum carbide is the dominant factor of its excellent performance. The metal-semiconductor interface formed by the combination of copper nanoparticles and Mo2C not only provides sufficient active sites, but also promotes the separation of photo-generated electron-hole pairs to further improve the utilization efficiency of holes and electrons, thereby efficiently removing antibiotic pollutants in complex water quality while reducing H + H2 is produced.

[0080] Example 6

[0081] The preparation method of this example is the same as that of Example 1, except that 3.0 mmol of copper acetate monohydrate (0.6 g) and 0.3 mmol of hydrated phosphomolybdic acid (0.62 g) are added to solution B, and the solution is not added with melamine after mixing, to prepare Cu / Mo2O-10-800.

[0082] Example 7

[0083] The preparation method of this example is the same as that of Example 1, except that 3.0 mmol of copper acetate monohydrate (0.6 g) and 0.9 mmol of hydrated phosphomolybdic acid (1.86 g) are added to solution B, and the solution is not added with melamine after mixing, to prepare Cu / Mo2O-3.3-800.

[0084] Example 8

[0085] The preparation method of this example is the same as that of Example 1, except that 3.0 mmol of copper acetate monohydrate (0.6 g) and 1.2 mmol of hydrated phosphomolybdic acid (2.48 g) are added to solution B, and the solution is not added with melamine after mixing, to prepare Cu / Mo2O-2.5-800.

[0086] Example 9

[0087] The preparation method of this example is the same as that of Example 1, except that the amount of melamine added is 0.6 g, and Cu / Mo2C / NC-5-1.0-800 is prepared.

[0088] Example 10

[0089] The preparation method of this example is the same as that of Example 1, except that the amount of melamine added is 0.3 g, and Cu / Mo2C / NC-5-0.5-800 is prepared.

[0090] Example 11

[0091] The preparation method of this example is the same as that of Example 1, except that the amount of melamine added is 0.075 g, and Cu / Mo2C / NC-5-0.125-800 is prepared.

[0092] Experimental Example 2

[0093] The removal rate of DOX in water and the H2 production of the products of Example 1 and Examples 6-11 are tested, and the testing method is as follows:

[0094] A single-chamber effective volume of 100 ml H-type double-chamber reactor is selected as a photoelectrocatalytic reactor, and the FTO working electrode prepared by drop coating method of the catalyst prepared in the above Example 1 and Examples 6-11 is used as an anode (effective area is 1×2 cm 2 ), and a foil is used as a cathode (effective area is 1×2 cm 2 ) to construct a PEC reactor, and the anode chamber and the cathode chamber of the reactor are separated by a N117 proton membrane with a diameter of 30 mm, the electrolyte solution in the anode solution is 0.1 mol / L Na2SO4 solution, the electrolyte solution in the cathode solution is 1.0 mol / L KOH solution, the anode light source is a 250W xenon lamp with an ultraviolet filter (λ>420 nm); 100 mL of simulated organic wastewater with an initial concentration of DOX of 10 mg / L is configured, the direct current power voltage is 2.5 V, the light intensity is 2.4 W / cm 2 , the pH of the wastewater is not adjusted (at this time the pH of the wastewater is 6.54), and the reaction is carried out by fully stirring with a magnetic stirrer at 25°C, and the residual concentration of DOX at the anode and the H2 production at the cathode are measured at 1 min, 3 min, 5 min, 7 min, 10 min and 15 min, respectively, and the removal rate of DOX and the hydrogen production are calculated.

[0095] The calculation results are shown in Figures 3-6 , the optimal molar ratio of copper to molybdenum is 1:5, and the optimal amount of melamine added is 25% (0.25) compared with copper acetate.

[0096] Example 12

[0097] The preparation method of this example is the same as that of Example 1, except that the temperature of the tube furnace is raised to 700℃, and Cu / Mo2C / NC-5-0.25-700 is prepared.

[0098] Example 13

[0099] The preparation method of this example is the same as that of Example 1, except that the temperature of the tube furnace is raised to 900℃, and Cu / Mo2C / NC-5-0.25-900 is prepared.

[0100] Experimental Example 3

[0101] The removal rate of DOX in water and the H2 production of the products of Example 1 and Examples 12-13 are tested, and the testing method is as follows:

[0102] A single-chamber effective volume of 100ml H-type double-chamber reactor is selected as a photoelectrocatalytic reactor, and the FTO working electrode prepared by drop coating method of the catalyst prepared in the above Example 1 and Examples 12-13 is used as an anode (effective area is 1×2cm 2 ), and a foil is used as a cathode (effective area is 1×2cm 2 ) to construct a PEC reactor, the anode chamber and the cathode chamber of the reactor are separated by a N117 proton membrane with a diameter of 30mm, the electrolyte solution in the anode solution is 0.1mol / L Na2SO4 solution, the electrolyte solution in the cathode solution is 1.0mol / L KOH solution, the anode light source is a 250W xenon lamp with an ultraviolet filter (λ>420nm); 100mL of simulated organic wastewater with an initial concentration of DOX of 10mg / L is configured, the direct current power voltage is 2.5V, the light intensity is 2.4W / cm 2 , the pH of the wastewater is not adjusted (at this time the pH of the wastewater is 6.54), and the reaction is carried out by a magnetic stirrer at 25℃, the residual concentration of DOX at the anode and the H2 production at the cathode are measured at 1min, 3min, 5min, 7min, 10min and 15min, respectively, and the removal rate of DOX and the hydrogen production are calculated.

[0103] The calculation results are shown in Figure 7 and Figure 8 , and the best calcination temperature is 800℃.

[0104] Figures 9-12 The scanning electron microscope images of the catalysts prepared in Example 1, Example 2 and Example 5 without calcination are shown in Figures 9-11It can be seen that the catalyst in Example 5, before calcination, exhibits a distinct octahedral structure. After the addition of phosphomolybdic acid, it retains its octahedral shape, but its surface becomes smoother, and the crystal structure of the catalyst becomes more pronounced. However, the addition of melamine does not result in an octahedral structure, indicating that the addition of melamine disrupts its structural formation. Furthermore, from... Figure 12 It can be seen that the catalyst surface in Example 1 is rougher, and the calcined catalyst exhibits a cluster structure. X-ray diffraction patterns of the catalysts prepared in Examples 1, 2, 5, and the uncalcined catalyst of Example 5 are shown below. Figure 13 As shown in the figure, the catalyst prepared in Example 5 (uncalcined) exhibited distinct characteristic peaks at 2θ = 6.5°, 9.5°, 11.5°, 13.4°, 19.3°, and 26°, confirming the formation of its crystalline phase. The intensity variations of the different diffraction peaks can be attributed to the different degrees of hydration in the samples. Furthermore, the catalysts of Examples 1, 2, and 5 exhibited distinct characteristic peaks at 2θ = 43.4°, 50.6°, and 74.3°, confirming the presence of Cu nanoparticles. The catalyst of Example 2 confirmed the presence of MoO2 at 2θ = 36.5° and 53.3°, and the catalyst of Example 1 confirmed the presence of Mo2C at 2θ = 34.3° and 39.4°.

[0105] Example 14

[0106] This embodiment provides a melamine-mediated POMOF-derived molybdenum carbide-supported copper nanoparticle catalyst, and the preparation steps are as follows:

[0107] 1) Under magnetic stirring, H3BTC (0.62 g, 3.0 mmol) was dissolved in methanol solution (40 ml) to form solution A. Copper acetate monohydrate (0.6 g, 3.0 mmol) and phosphomolybdic acid hydrate (1.24 g, 0.6 mmol) were dissolved in methanol solution (40 ml) to form solution B. Then, solution A was slowly added to solution B and 0.15 g of melamine was added. The mixture was stirred at room temperature for 14 h to obtain a blue-green precipitate. The precipitate was washed twice with methanol and twice with distilled water, centrifuged, collected, and dried at 60 °C overnight to obtain the POMOF / melamine catalyst.

[0108] 2) The POMOF / melamine catalyst was placed in a quartz boat and then transferred to a tube furnace. Nitrogen gas was introduced into the tube furnace to purge the air. Then, under a nitrogen atmosphere, the temperature was increased to 800℃ at a heating rate of 5℃ / min and held for 2h for pyrolysis. After cooling to room temperature, the melamine-mediated POMOF-derived Cu / Mo2C / NC-5-0.25-800 catalyst was obtained.

[0109] Experiment Example 4

[0110] The catalyst prepared in Example 14 was set up in four treatment groups: a single-chamber effective volume of 100 ml H-type double-chamber reactor was selected as the photoelectrocatalytic reactor, the FTO working electrode prepared by drop coating method of the catalyst prepared in the above Examples 1 and 12-13 was selected as the anode (effective area of 1 x 2 cm 2 ), and the foil was selected as the cathode (effective area of 1 x 2 cm 2 ) to construct the PEC reactor, the anode chamber and the cathode chamber of the reactor were separated by a N117 proton membrane with a diameter of 30 mm, the electrolyte solution in the anode solution was 0.1 mol / L Na2SO4 solution, the electrolyte solution in the cathode solution was 1.0 mol / L KOH solution, the anode light source was a 250 W xenon lamp with an ultraviolet filter (λ > 420 nm); 100 mL of simulated organic wastewater with an initial DOX concentration of 10 mg / L was prepared, the direct current power voltage was 0.5 V (treatment group 1), 1.5 V (treatment group 2), 2.5 V (treatment group 3), 3.5 V (treatment group 4), the light intensity was 2.4 W / cm 2 , and the pH of the wastewater was not adjusted (at this time the pH of the wastewater was 6.54), the reaction was carried out at 25°C by magnetic stirrer with sufficient stirring, the residual concentration of anode DOX and the hydrogen production of cathode were measured at 1 min, 3 min, 5 min, 7 min, 10 min and 15 min, respectively, and the removal rate of DOX and the hydrogen production were calculated.

[0111] The calculation results are shown in Figure 14 and 15 , and the optimal external voltage is 2.5 V, and the voltage is too low to transfer the photo-generated electrons to the cathode, which leads to the recombination of photo-generated electron-hole pairs, reduces the degradation rate and hydrogen production, and the high voltage leads to the electrolysis of water, which competes with the degradation of DOX and reduces the degradation efficiency.

[0112] Experimental Example 5

[0113] The catalyst prepared in Example 1 was set up in six treatment groups: a single-chamber effective volume of 100 ml H-type double-chamber reactor was selected as the photoelectrocatalytic reactor, the FTO working electrode prepared by drop coating method of the catalyst prepared in the above Examples 1 and 12-13 was selected as the anode (effective area of 1 x 2 cm 2 ), and the foil was selected as the cathode (effective area of 1 x 2 cm 2) Construct a PEC reactor, the anode chamber and the cathode chamber of the reactor are separated by N117 proton membrane with a diameter of 30 mm, the electrolyte solution in the anode solution is 0.1 mol / L Na2SO4 solution, the electrolyte solution in the cathode solution is 1.0 mol / L KOH solution, the anode light source is a 250W xenon lamp with an ultraviolet filter (λ>420nm); configure 100mL of simulated organic sewage with an initial DOX concentration of 10mg / L, the direct current power voltage is 2.5V, the light intensity is 2.4W / cm 2 , respectively, adjust the initial pH of the sewage to 3 (treatment group 1), 5 (treatment group 2), 7 (treatment group 3), 9 (treatment group 4), 11 (treatment group 5), and the original water (treatment group 6), and react at 25°C by magnetic stirrer, respectively, at 1min, 3min, 5min, 7min, 10min, 15min, measure the residual concentration of anode DOX and the production of cathode H2, calculate the removal rate of DOX and the amount of hydrogen production.

[0114] The calculation results are shown in Figure 16 and Figure 17 , and the best pH treatment range is 5-11, which shows that it has significant pH adaptability in alkaline water bodies.

[0115] Experimental example 6

[0116] In example 1, the catalyst prepared is respectively set up 4 treatment groups: select a single-chamber effective volume of 100ml H-shaped double-chamber reactor as a photoelectrocatalytic reactor, the FTO working electrode prepared by drop coating method of the catalyst prepared in the above example 1 and examples 12-13 is used as an anode (effective area is 1×2cm 2 ), and the foil is used as a cathode (effective area is 1×2cm 2 ) to construct a PEC reactor, the anode chamber and the cathode chamber of the reactor are separated by N117 proton membrane with a diameter of 30 mm, the electrolyte solution in the anode solution is 0.1 mol / L Na2SO4 solution, the electrolyte solution in the cathode solution is 1.0 mol / L KOH solution, the anode light source is a 250W xenon lamp with an ultraviolet filter (λ>420nm); configure 100mL of simulated organic sewage with an initial concentration of 10mg / L: tetracycline (treatment group 1), aureomycin (treatment group 2), doxycycline (treatment group 3), ciprofloxacin (treatment group 4), the direct current power voltage is 2.5V, the light intensity is 2.4W / cm 2Without adjusting the pH of the wastewater (at this time the pH of the wastewater is 6.54), the reaction is carried out at 25°C by a magnetic stirrer for full stirring, and the residual concentration of the anode pollutants and the cathode H2 production are measured at 1 min, 3 min, 5 min, 7 min, 10 min and 15 min, respectively, to calculate the removal rate of the pollutants and the hydrogen production.

[0117] The calculation results are shown in Table 1, which show that the catalyst has certain removal ability and hydrogen production ability for the tetracycline antibiotics. Figures 18-19

[0118] Experimental Example 7

[0119] The catalyst prepared in Example 1 is used to test the cycle stability of the catalyst: a single-chamber effective volume of 100 ml H-type double-chamber reactor is selected as a photoelectrocatalytic reactor, the FTO working electrode prepared by drop coating method of the catalyst prepared in the above Example 1 and Examples 12-13 is used as an anode (effective area is 1x2 cm 2 ), and a foil is used as a cathode (effective area is 1x2 cm 2 ) to construct a PEC reactor, the anode chamber and the cathode chamber of the reactor are separated by a N117 proton membrane with a diameter of 30 mm, the electrolyte solution in the anode solution is 0.1 mol / L Na2SO4 solution, the electrolyte solution in the cathode solution is 1.0 mol / L KOH solution, the anode light source is a 250W xenon lamp with an ultraviolet filter (λ>420 nm); 100 mL of simulated organic wastewater with an initial DOX concentration of 10 mg / L is configured, the direct current power voltage is 2.5V, and the light intensity is 2.4W / cm 2 Without adjusting the pH of the wastewater (at this time the pH of the wastewater is 6.54), the reaction is carried out at 25°C by a magnetic stirrer for full stirring, and the residual concentration of the anode pollutants and the cathode H2 production are measured at 1 min, 3 min, 5 min, 7 min, 10 min and 15 min, respectively, to calculate the removal rate of the pollutants and the hydrogen production.

[0120] The test results are shown in Table 2, which show that the catalyst has significant stability in 4 cycles, and can restore certain performance after being fired. Figures 20-21

[0121] Experimental Example 8

[0122] ​​Quenching experiments were carried out with the catalysts prepared in Examples 1-5, with four treatment groups and one untreated group: a single-chamber effective volume of 100 ml H-type double-chamber reactor was selected as the photoelectrocatalytic reactor, and the FTO working electrode prepared by drop coating the catalysts prepared in Examples 1 and 12-13 was used as the anode (effective area of 1 x 2 cm 2 ), and a foil was used as the cathode (effective area of 1 x 2 cm 2 ) to construct the PEC reactor, the anode chamber and the cathode chamber of the reactor were separated by a N117 proton membrane with a diameter of 30 mm, the electrolyte solution in the anode solution was 0.1 mol / L Na2SO4 solution, the electrolyte solution in the cathode solution was 1.0 mol / L KOH solution, the anode light source was a 250W xenon lamp with an ultraviolet filter (λ>420 nm); 100 mL of simulated organic wastewater with an initial DOX concentration of 10 mg / L was prepared, the direct current power voltage was 2.5 V, the light intensity was 2.4 W / cm 2 , the pH of the wastewater was not adjusted (at this time the pH of the wastewater was 6.54), and then 500 mmol / L of tert-butyl alcohol (TBA) was added as a hydroxyl radical quencher (treatment group 1), 10 mmol / L of ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) was added as a hole quencher (treatment group 2), 10 mmol / L of furfuryl alcohol (FFA) was added as a singlet oxygen quencher (treatment group 3), and 10 mmol / L of nitro blue tetrazolium (NBT) was added as a superoxide radical quencher (treatment group 4), and the reaction was carried out by magnetic stirring at 25°C, and the residual concentration of anode DOX and the cathode H2 production were measured at 1 min, 3 min, 5 min, 7 min, 10 min, and 15 min, respectively, and the DOX removal rate and hydrogen production were calculated.

[0123] The calculation results are shown in Figures 22-23 , which shows that it is a hole-dominant reaction.

[0124] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. Application of melamine-mediated POMOF-derived molybdenum carbide supported copper nanoparticle catalyst in photoelectrocatalytic removal of wastewater antibiotics while producing H2, characterized in that, The preparation method of the melamine-mediated POMOF-derived molybdenum carbide supported copper nanoparticle catalyst comprises the following steps: (1) mixing, stirring, standing, centrifuging, washing, drying and dehydrating methanol solution of trimesic acid, methanol mixed solution of copper acetate monohydrate and hydrated phosphomolybdic acid and melamine in sequence to obtain a POMOF / melamine catalyst precursor; (2) pyrolyzing the POMOF / melamine catalyst precursor to obtain a melamine-mediated POMOF-derived molybdenum carbide supported copper nanoparticle catalyst; The pyrolysis step in the step (2) uses nitrogen as a protective gas, the heating rate is 5-10 ℃ / min, the pyrolysis temperature is 700-900 ℃, and the pyrolysis holding time is 2-3 h; The melamine-mediated POMOF-derived molybdenum carbide supported copper nanoparticle catalyst is prepared by a drop coating method to obtain an anode of a photoelectrocatalytic reactor, and the loading of the catalyst is 5 mg / cm 2 ; The antibiotic includes one or more of tetracycline, aureomycin, doxycycline and ciprofloxacin.

2. Use according to claim 1, characterized in that, The concentration of the methanol solution of trimesic acid in the step (1) is 2%; the concentration of the methanol mixed solution of copper acetate monohydrate and hydrated phosphomolybdic acid is 3.8-9.7%.

3. Use according to claim 1, characterized in that, The molar ratio of trimesic acid, copper acetate monohydrate and hydrated phosphomolybdic acid in the step (1) is 1:1:0.

2. The mass ratio of the copper acetate monohydrate to the melamine is 4:

1.

4. Use according to claim 1, characterized in that, The stirring time in the step (1) is 14 h.

5. The use according to claim 1, characterized in that, The photoelectrocatalytic reactor is an H-type double-chamber reactor, wherein the anode is the anode prepared in claim 1, and the cathode is a platinum sheet electrode.

6. Use according to claim 1, characterized in that, The anode electrolyte solution in the H-type double-chamber reactor is a 0.1 mol / L sodium sulfate solution, and the cathode electrolyte is a 1.0 mol / L potassium hydroxide solution. The pH value of the reaction system when removing the antibiotics in wastewater is 3-11, the temperature of the reaction system is 25-30 DEG C, the voltage is 0.5-3.5V, and the light intensity is 2.4 W / cm 2 .

Images