阅读说明：本技术 一种镍离子掺杂的氧化锌/硫化镉高性能分解水产氢光催化剂及制备方法 (Nickel ion doped zinc oxide/cadmium sulfide high-performance water decomposition hydrogen production photocatalyst and preparation method thereof ) 是由 范大勇 彭国良 刘勇平 于 2020-12-20 设计创作，主要内容包括：一种镍离子掺杂的氧化锌/硫化镉高性能分解水产氢光催化剂及制备方法,本发明的镍离子掺杂的氧化锌/硫化镉光催化剂由氧化锌,硝酸,柠檬酸,四水硝酸镉,乙酸镍,硫脲制成。方法：使用一定量的蒸馏水和浓硝酸溶解氧化锌,加入乙酸镍、柠檬酸并溶解,放入60℃烘箱干燥,形成白色凝胶,在马弗炉中500℃保温半小时,得到纳米级掺杂镍氧化锌；将硫脲、硝酸镉溶解于蒸馏水,加入掺杂镍纳米氧化锌后放入80℃水浴锅边搅拌边加热180分钟,取烧杯底部粉末经洗涤烘干放入450℃氩气中退火90分钟,得到镍离子掺杂的氧化锌/硫化镉复合光催化剂。(The invention discloses a nickel ion doped zinc oxide/cadmium sulfide high-performance water decomposition hydrogen production photocatalyst and a preparation method thereof. The method comprises the following steps: dissolving zinc oxide with a certain amount of distilled water and concentrated nitric acid, adding nickel acetate and citric acid, dissolving, drying in a 60 ℃ oven to form white gel, and keeping the temperature in a muffle furnace at 500 ℃ for half an hour to obtain nano-grade nickel-doped zinc oxide; dissolving thiourea and cadmium nitrate in distilled water, adding nickel-doped nano zinc oxide, then placing the mixture into a water bath kettle at 80 ℃ for heating for 180 minutes while stirring, taking powder at the bottom of a beaker, washing and drying the powder, and placing the powder into argon gas at 450 ℃ for annealing for 90 minutes to obtain the nickel ion-doped zinc oxide/cadmium sulfide composite photocatalyst.)

1. A nickel-doped nano zinc oxide/cadmium sulfide powder photocatalyst has a molecular formula of Ni: ZnO/CdS, and is characterized in that Ni is doped into a composite ZnO (hexagonal phase)/CdS (hexagonal phase) nanocrystal and is synthesized step by step in the following mode:

(1) preparing a precursor solution:

precursor solution of nano ZnO: weighing 0.5-1.0g of raw material a, adding a certain amount of distilled water and 1-3mL of high-concentration inorganic acid to dissolve the raw material a, then uniformly mixing the raw material a with the solution D, and then weighing 1.0-1.5g of citric acid to add into the solution to obtain a solution A; precursor solution of CdS (B and C): dissolving the raw material B in deionized water to obtain a solution B of 6-10g/L, and dissolving the raw material C in deionized water to obtain a solution C of 6-10 g/L; wherein the raw material b is a water-soluble sulfur-containing inorganic compound, and the raw material c is nitrate of soluble Cd; precursor solution D of Ni ion: dissolving a certain amount of raw material D in deionized water to obtain a solution D;

(2) drying and annealing treatment:

putting the solution A into a drying oven at 60 ℃ for drying until white gel is formed, then putting the crucible into a muffle furnace at 500 ℃, and preserving heat for half an hour to obtain nano-scale zinc oxide F; putting the beaker containing the solutions B and C and a certain amount of F into a water bath kettle at the temperature of 80 ℃, and heating for 180 minutes while stirring; and (3) taking powder at the bottom of the beaker after the reaction is finished, washing the powder with distilled water for five times, putting the washed powder into a drying oven at 60 ℃ for drying, and annealing the dried powder in argon atmosphere at 450 ℃ for 90 minutes to obtain the nickel-doped nano zinc oxide/cadmium sulfide powder photocatalyst.

2. The nickel-doped nano zinc oxide/cadmium sulfide powder photocatalyst as claimed in claim 1, wherein the raw material a is commercial ZnO powder.

3. The nickel-doped nano zinc oxide/cadmium sulfide powder photocatalyst as claimed in claim 1, wherein the raw material d is soluble divalent ni (ii) salt.

4. The nickel-doped nano zinc oxide/cadmium sulfide powder photocatalyst as claimed in claim 1, wherein the raw material b is thiourea.

5. The nickel-doped nano zinc oxide/cadmium sulfide powder photocatalyst as claimed in claim 1, wherein the raw material c is cadmium nitrate.

6. The nickel-doped nano zinc oxide/cadmium sulfide powder photocatalyst as claimed in claim 1, wherein the molar ratio of the raw material D added to the preparation solution D to the raw material a added to the preparation solution A is 0.1-15%.

Technical Field

The invention relates to the technical field of photocatalysts, in particular to a nickel ion doped zinc oxide/cadmium sulfide high-performance water-decomposing hydrogen-producing photocatalyst and a preparation method thereof.

Background

Due to the ever-increasing demand of people for living standard of substances, the over-development and the use of fossil fuels have caused huge greenhouse effect on the earth and threaten the survival of human beings. There is an urgent need to find a new green, clean and sustainable energy source to replace the fossil fuels that are increasingly exhausted. The preparation of hydrogen by directly decomposing water by solar photocatalysis is a promising technology, and because solar energy is used as energy and is directly converted into a high-heat-value hydrogen energy (the heat generated by combusting hydrogen with the same mass is 2.56 times of natural gas and 2.95 times of common gasoline), and the combustion of the hydrogen does not contain any pollutant, the photocatalytic water decomposition technology is considered to be an ideal future energy solution.

For the photocatalytic technology, the most central part is the photocatalyst, the photocatalytic performance is practical, and the activity or energy conversion efficiency of the photocatalyst is the most critical index. An ideal photocatalytic water splitting catalyst should have good absorption properties in the visible region of the solar spectrum, good hydrogen production activity under visible light and long-term stability, and reduce the cost of preparing a unit mass of photocatalyst, including energy consumption, the amount of noble metal used, and the like, as much as possible.

Disclosure of Invention

The invention relates to a zinc oxide/cadmium sulfide photocatalyst doped with nickel ions and a preparation method thereof. The catalyst is characterized by having the characteristics of nanoscale powder, having the absorption capacity on a visible light region of a solar spectrum, having high efficiency of hydrogen production by photocatalytic decomposition of water under visible light, having the hydrogen production activity under visible light (with the wavelength of more than 420nm) of 8.5mmol/g/h, being 28 times of that of a photocatalyst without nickel-doped zinc oxide/cadmium sulfide, and not needing noble metal as a cocatalyst. The doping element nickel needed by the preparation of the catalyst has low dosage and low price, the preparation method is simple, the energy consumption is low, the yield is high, and the method is suitable for large-scale industrial preparation.

The technical scheme of the invention is as follows:

a nickel-doped nano zinc oxide/cadmium sulfide powder photocatalyst has a molecular formula of Ni: ZnO/CdS, and is characterized in that Ni is doped into a composite ZnO (hexagonal phase)/CdS (hexagonal phase) nanocrystal and is synthesized step by step in the following mode:

(1) preparing a precursor solution:

precursor solution of nano ZnO: weighing 0.5-1.0g of raw material a, adding a certain amount of distilled water and 1-3mL of high-concentration inorganic acid to dissolve the raw material a, then uniformly mixing the raw material a with the solution D, and then weighing 1.0-1.5g of citric acid to add the citric acid into the solution to obtain a solution A. Wherein the raw material a is commercial ZnO powder.

Precursor solution of CdS: dissolving the raw material B in deionized water to obtain a solution B of 6-10g/L, and dissolving the raw material C in deionized water to obtain a solution C of 6-10 g/L; wherein the raw material b is a water-soluble sulfur-containing inorganic compound, and the raw material c is nitrate of soluble Cd.

Precursor solution of Ni ion: dissolving the raw material D in deionized water to obtain 0.03-0.1g/L solution D; wherein the raw material d is soluble Ni acetate.

(2) Drying and annealing treatment:

and (3) drying the solution A in an oven at 60 ℃ until white gel is formed, then placing the crucible in a muffle furnace at 500 ℃, and preserving heat for half an hour to obtain the nano-nickel doped nano-zinc oxide F.

And putting the beaker containing the solutions B and C and a certain amount of F into a water bath kettle at the temperature of 80 ℃ and heating for 180 minutes while stirring. And (3) taking powder at the bottom of the beaker after the reaction is finished, washing the powder with distilled water for five times, putting the washed powder into a drying oven at 60 ℃ for drying, and annealing the dried powder in argon atmosphere at 450 ℃ for 90 minutes to obtain the nickel-doped nano zinc oxide/cadmium sulfide powder photocatalyst.

Drawings

FIG. 1 is an X-ray powder diffraction pattern of nano-ZnO/CdS photocatalysts with different Ni contents prepared in examples 1, 2, 3 and 4 of the present invention;

FIG. 2 is an SEM image of a 1% nickel doped nano zinc oxide/cadmium sulfide powder photocatalyst prepared in example 1 of the present invention;

FIG. 3 is an SEM image of an undoped nano zinc oxide/cadmium sulfide powder photocatalyst prepared in example 4 of the present invention;

FIG. 4 is a graph of the UV-visible diffuse reflectance absorption spectrum of a nano-ZnO/CdS powder photocatalyst prepared according to different amounts of Ni doping in examples 1, 2, 3 and 4 of the present invention;

FIG. 5 shows the photocatalytic hydrogen production for 5 hours for the nano-ZnO/CdS photocatalysts with different Ni doping amounts prepared in the embodiments 1, 2, 3 and 4 of the present invention;

FIG. 6 shows the stability test of photocatalytic hydrogen production for 5 hours each time after 5 cycles of the 1% Ni-doped nano-ZnO/CdS powder photocatalyst prepared in example 1 of the present invention;

FIG. 7 shows the average hydrogen production per hour of nano zinc oxide/cadmium sulfide powder photocatalysts with different nickel doping amounts prepared in examples 1, 2, 3 and 4 of the present invention.

Detailed Description

Example 1 was carried out:

the process for preparing the nickel-doped zinc oxide/cadmium sulfide catalyst is carried out in two steps:

synthesizing nickel-doped zinc oxide: weighing nickel acetate tetrahydrate and 0.8098g of zinc oxide (the molar ratio is 1:99) into a porcelain crucible, adding a certain amount of distilled water and 2mL of concentrated nitric acid to dissolve the zinc oxide, then weighing 1.5g of citric acid to dissolve the zinc oxide, and after the solution is clarified, putting the solution into an oven at 60 ℃ for drying to form gel. Then, it was placed in a muffle furnace at 500 ℃ and incubated for half an hour.

Synthesis of Ni, ZnO/CdS: first, 0.7g of thiourea was weighed and dissolved in 100mL of distilled water, and then 0.6169g of Cd (NO) was added thereto₃)₂·5H₂O and 0.3255g of nickel-doped zinc oxide (mass ratio 1:4), and the beaker was then placed in a 80 ℃ water bath and heated for 180 minutes with stirring. And after the reaction is finished, taking powder at the bottom of the beaker, washing the powder with distilled water for five times, drying the powder in a drying oven at 60 ℃, and annealing the dried powder in argon atmosphere at 450 ℃ for 90 minutes.

Example 2 was carried out:

the process for preparing the nickel-doped zinc oxide/cadmium sulfide catalyst is carried out in two steps:

synthesizing nickel-doped zinc oxide: weighing nickel acetate tetrahydrate and 0.8098g of zinc oxide (the molar ratio is 0.5:99.5) into a porcelain crucible, adding a certain amount of distilled water and 2mL of concentrated nitric acid to dissolve the zinc oxide, weighing 1.5g of citric acid to dissolve the zinc oxide, clarifying the solution, and drying in an oven at 60 ℃ to form gel. Then, it was placed in a muffle furnace at 500 ℃ and incubated for half an hour.

Ni-ZnO/CdS synthesis: first, 0.7g of thiourea was weighed and dissolved in 100mL of distilled water, and then 0.6169g of Cd (NO) was added thereto₃)₂·5H₂O and 0.3255g of nickel-doped zinc oxide (mass ratio 1:4), and the beaker was then placed in a 80 ℃ water bath and heated for 180 minutes with stirring. And after the reaction is finished, taking powder at the bottom of the beaker, washing the powder with distilled water for five times, drying the powder in a drying oven at 60 ℃, and annealing the dried powder in argon atmosphere at 450 ℃ for 90 minutes.

Example 3 of implementation:

synthesizing nickel-doped zinc oxide: weighing nickel acetate tetrahydrate and 0.8098g of zinc oxide (molar ratio is 2:98) into a porcelain crucible, adding a certain amount of distilled water and 2mL of concentrated nitric acid to dissolve the zinc oxide, weighing 1.5g of citric acid to dissolve the zinc oxide, clarifying the solution, and drying in an oven at 60 ℃ to form gel. Then, it was placed in a muffle furnace at 500 ℃ and incubated for half an hour.

Synthesis of Ni, ZnO/CdS: first, 0.7g of thiourea was weighed and dissolved in 100mL of distilled water, and then 0.6169g of Cd (NO) was added thereto₃)₂·5H₂O and 0.3255g of nickel-doped zinc oxide (mass ratio 1:4) were added, and the beaker was placed in a 80 ℃ water bath and heated for 180 minutes while stirring. And after the reaction is finished, taking powder at the bottom of the beaker, washing the powder with distilled water for five times, drying the powder in a drying oven at 60 ℃, and annealing the dried powder in argon atmosphere at 450 ℃ for 90 minutes.

Example 4 of implementation:

synthesizing nickel-doped zinc oxide: 0.8098g of zinc oxide is weighed into a porcelain crucible, a certain amount of distilled water and 2mL of concentrated nitric acid are added to dissolve the zinc oxide, 1.5g of citric acid is weighed into the solution to dissolve the zinc oxide, and the solution is placed into an oven at 60 ℃ to be dried after being clarified to form gel. Then the mixture is put into a muffle furnace at 500 ℃ and is kept warm for half an hour to obtain the non-doped zinc oxide.

Ni-ZnO/CdS synthesis: first, 0.7g of thiourea was weighed and dissolved in 100mL of distilled water, and then 0.6169g of Cd (NO) was added thereto₃)₂·5H₂O and 0.3255g of undoped zinc oxide (mass ratio 1:4), and then the beaker was placed in a water bath kettle at 80 ℃ and heated for 180 minutes with stirring. And after the reaction is finished, taking powder at the bottom of the beaker, washing the powder with distilled water for five times, drying the powder in a drying oven at 60 ℃, and annealing the dried powder in argon atmosphere at 450 ℃ for 90 minutes.

Referring to the attached figure 1, the X-ray powder diffraction patterns of different nickel-doped nano zinc oxide/cadmium sulfide powder photocatalysts prepared in examples 1, 2, 3 and 4 are shown; all the components meet the standard spectrograms of zinc oxide and cadmium sulfide, no impurity phase is generated, the intensity of diffraction peak is high, and the crystallinity is good.

Referring to FIG. 2, is an SEM image of the undoped nano zinc oxide/cadmium sulfide powder photocatalyst of example 4; the characteristic size is about 20-30nm of small spheres, and the monodispersity is good.

Referring to FIG. 3, it is an SEM image of the 1% Ni-doped nano-ZnO/CdS powder photocatalyst prepared in example 1; the characteristic size is about 50nm of particle globules, and the size is uniform. .

Referring to the attached figure 4, the ultraviolet visible diffuse reflection absorption spectrum of the nano zinc oxide/cadmium sulfide powder photocatalyst under different nickel doping amounts prepared in examples 1, 2, 3 and 4 is shown; the nickel-doped optical fiber has better visible light region absorption performance.

Referring to the attached figure 5, the amount of the nano zinc oxide/cadmium sulfide powder photocatalyst with different nickel doping amounts prepared in the examples 1, 2, 3 and 4 is the amount of hydrogen produced by photocatalysis for 5 hours; the photocatalyst (0.03g) was dispersed in 30mL of Na of 0.1moL/L concentration₂SO₃And 0.2moL/L Na₂S·9H₂In the O-mixed solution, a 300W xenon lamp (. lamda.) was used>420nm filter) as a visible light source to illuminate the reactor vertically. Before illumination, the reactor is vacuumized and then is communicatedArgon is introduced as a protective gas to ensure that the internal pressure and the external pressure of the reactor are equal. Every hour of light exposure, 200. mu.L of gaseous product was extracted from the reactor and the amount of hydrogen produced was determined by gas chromatography (TCD method, GC-7900, China). The doping of nickel obviously improves the photocatalytic hydrogen production amount in unit time, and different nickel doping concentrations have obvious influence on the hydrogen production activity.

Referring to the attached figure 6, the 2% nickel-doped nano zinc oxide/cadmium sulfide powder photocatalyst prepared in example 1 is subjected to 5 cycles, and the stability of photocatalytic hydrogen production is tested for 5 hours each time; after 5 cycles of photocatalytic hydrogen production test for 5 hours each time, the catalyst still maintains more than 70% of the initial hydrogen production.

Referring to fig. 7, the average hydrogen production per hour of the nano zinc oxide/cadmium sulfide powder photocatalysts with different nickel doping amounts prepared in examples 1, 2, 3 and 4 is shown. The optimized hydrogen production performance is obtained in the example 1, and the hydrogen production activity can reach 8.5mmol/g/h calculated by the catalyst in unit time and unit mass.

Although embodiments of the present invention have been shown and described, it will be understood that the embodiments described above are illustrative and should not be construed as limiting the invention, and that various changes, modifications, substitutions and alterations can be made therein by those skilled in the art without departing from the spirit and scope of the invention.