A graphitic phase carbon nitride / polyaniline / nickel sulfide heterostructure photocatalyst and a preparation method thereof

Abstract

The application relates to a preparation method of a g-C3N4-PANI-NiS heterostructure photocatalyst, which comprises the following steps: (1) g-C3N4 nanosheet preparation: placing a carbon-nitrogen source in a ceramic crucible with a cover in a muffle furnace for calcination to obtain light yellow g-C3N4 powder, then placing the g-C3N4 powder in a porcelain boat in a tube furnace for secondary calcination under an air atmosphere, washing the synthesized sample with deionized water and anhydrous ethanol for three times, drying in a vacuum drying box overnight, and then grinding to obtain white g-C3N4 nanosheets; (2) g-C3N4-PANI preparation: dispersing aniline in a 0.1 mol / L HCl solution, adding appropriate ammonium persulfate and g-C3N4 nanosheets into the mixed solution, continuously stirring under an ice bath, and obtaining green precipitates as the product; (3) ultrasonic dispersion of the g-C3N4-PANI in deionized water, sequentially adding a nickel source and a sulfur source and appropriate triethanolamine, ultrasonic dispersion to obtain a uniformly dispersed suspension, irradiating the suspension in a photocatalytic reactor at room temperature by using a xenon lamp, and obtaining the g-C3N4-PANI-NiS heterostructure photocatalyst. The g-C3N4-PANI-NiS heterostructure photocatalyst prepared by the above method has good application in photocatalytic hydrogen evolution.

Description

Technical Field

[0001] This invention relates to a photocatalytic material, specifically to a method for preparing a g-C3N4-PANI-NiS heterostructure photocatalyst, belonging to the field of materials synthesis technology. Background Technology

[0002] Fossil fuels, upon which humanity depends for survival, are unsustainable and their reserves are finite. With the rapid development of global industry, the shortage of fossil fuels has led to serious concerns about the ever-increasing energy demands of modern society. Simultaneously, the combustion of fossil fuels has caused increasingly prominent environmental problems. Therefore, developing low-cost, clean, and sustainable energy sources is of great significance. Since Fujishima's groundbreaking paper in 1972, it has been discovered that semiconductor photocatalysis technology can split water to produce hydrogen, converting low-density solar energy into high-density hydrogen energy for storage. From both energy utilization and environmental protection perspectives, hydrogen energy is a high-energy, pollution-free renewable energy source, making it an ideal energy source for the 21st century. Therefore, the development of hydrogen energy is imperative.

[0003] Non-metallic polymer semiconductor graphitic carbon nitride (g-C3N4) has been actively and extensively studied in the field of photocatalytic water splitting due to its advantages such as wide availability of precursors, simple preparation methods, environmental friendliness (no heavy metal pollution), high photochemical stability, and band structure suitable for photocatalytic hydrogen / oxygen production. However, the bottleneck problems of low carrier separation rate, weak water oxidation driving force, and limited visible light absorption of g-C3N4 have not been effectively solved, which has seriously limited the development of g-C3N4 photocatalytic water splitting. To overcome these problems, various strategies have been used to improve the photocatalytic hydrogen production efficiency of g-C3N4, including adjusting size, morphology, electronic structure, metal or non-metal deposition, and the construction of heterostructures. Among these, establishing heterostructure-connected photocatalytic systems is an effective method to promote charge separation of photogenerated electron-hole pairs.

[0004] Polyaniline (PANI) is a p-type conductive polymer with high light absorption coefficient and high electron mobility in the visible light range, attracting widespread attention in the field of photocatalysis. Both PANI and g-C3N4 possess π-conjugated structures, making them more likely to form composite materials. When PANI is coated onto the surface of g-C3N4, it not only improves the solar energy utilization rate of g-C3N4 but also provides a "transport channel" for the separation of photogenerated electron-hole pairs, promoting the separation of photogenerated charge carriers and thus enhancing its photocatalytic performance.

[0005] In photocatalytic hydrogen production, introducing a co-catalyst onto the photocatalyst surface is one of the most effective methods to improve photocatalytic performance because it has the advantages of accelerating interfacial electron transfer, inhibiting photoexcited charge recombination, and increasing effective active sites. NiS, as a transition metal chalcogenide, possesses excellent electrochemical performance and good conductivity, making it an effective co-catalyst in the photocatalytic hydrogen evolution reaction. Furthermore, compared to other non-noble metals, NiS has a lower activation energy when forming Ni-H bonds with adsorbed water on its surface during proton reduction, which promotes the hydrogen adsorption-reduction-desorption process, thereby significantly enhancing the photocatalytic hydrogen production reaction. Summary of the Invention

[0006] g-C3N4 nanosheets were synthesized via thermal polymerization. Then, using aniline as a monomer and ammonium persulfate as an oxidant, the synthesized polyaniline (PANI) was coated onto the g-C3N4 nanosheets in an acidic medium via chemical oxidative polymerization to prepare g-C3N4-PANI. Subsequently, NiS was supported on g-C3N4-PANI using photodeposition to prepare a g-C3N4-PANI-NiS photocatalyst. The prepared g-C3N4-PANI-NiS photocatalyst exhibited a high photocatalytic hydrogen evolution performance of 7.818 mmol / g under visible light. -1 h -1 .

[0007] This invention provides a method for preparing g-C3N4-PANI-NiS composite photocatalysts, characterized in that the method includes the following steps:

[0008] (1) Preparation of g-C3N4 nanosheets: The carbon and nitrogen source was placed in a covered ceramic crucible and calcined in a muffle furnace to obtain pale yellow g-C3N4 powder. The g-C3N4 powder was then placed in a ceramic boat and calcined again in an air atmosphere in a tube furnace. The synthesized sample was washed three times with deionized water and anhydrous ethanol, dried overnight in a vacuum drying oven, and then ground to obtain white g-C3N4 nanosheets.

[0009] (2) Preparation of g-C3N4-PANI: Aniline was dispersed in dilute hydrochloric acid solution, and an appropriate amount of ammonium persulfate and g-C3N4 nanosheets were added to the above mixture. The mixture was continuously stirred under ice bath, and the resulting green precipitate was the product.

[0010] (3) Preparation of g-C3N4-PANI-NiS: g-C3N4-PANI was ultrasonically dispersed in deionized water, and nickel source, sulfur source and appropriate amount of triethanolamine were added in sequence. The suspension was ultrasonically dispersed to obtain a uniformly dispersed suspension. The suspension was irradiated with a xenon lamp at room temperature in a photocatalytic reactor to obtain g-C3N4-PANI-NiS composite photocatalyst and dried.

[0011] In the above preparation method, in step (1), the carbon and nitrogen source can be selected from monoamine, dicyandiamine, melamine, urea or thiourea.

[0012] In the above preparation method, in step (1), the first calcination temperature is 300-1000℃, and the second calcination temperature is 100-500℃.

[0013] In the above preparation method, the stirring time in step (2) is 1 to 10 hours.

[0014] In the above preparation method, in step (2), the concentration of dilute hydrochloric acid is 0.05-0.5 mol / L.

[0015] In the above preparation method, the ultrasonic time in step (3) is 0.5 to 2 hours.

[0016] In the above preparation method, in step (3), the nickel source can be selected as nickel nitrate, nickel chloride, nickel sulfate, nickel bromide or nickel hydroxyl.

[0017] In the above preparation method, in step (3), the sulfur source is thiourea, thioacetamide, cysteine, etc.

[0018] In the above preparation method, the irradiation time in step (3) is 10 to 60 minutes.

[0019] In the above preparation method, the drying temperature in step (3) is 50-80℃.

[0020] The g-C3N4-PANI-NiS composite photocatalyst prepared using this technology has a simple preparation process and exhibits good photocatalytic activity. Attached Figure Description

[0021] Figure 1 This is the XRD pattern of the g-C3N4-PANI-NiS composite photocatalyst prepared in Example 1 of this invention.

[0022] Figure 2 This is a graph showing the photocatalytic hydrogen evolution performance of the g-C3N4-PANI-NiS composite photocatalyst prepared in Example 1 of this invention. Detailed Implementation

[0023] The technical solution of the present invention will be further described below with reference to the embodiments.

[0024] This invention proposes a method for preparing a high-performance g-C3N4-PANI-NiS composite photocatalyst. The method involves using thermal polymerization of g-C3N4 nanosheets, followed by chemical oxidative polymerization using aniline as a monomer and ammonium persulfate as an oxidant in an acidic medium to coat the synthesized polyaniline (PANI) onto the g-C3N4 nanosheets to obtain g-C3N4-PANI. Then, NiS is loaded onto the g-C3N4-PANI using photodeposition to prepare the g-C3N4-PANI-NiS composite photocatalyst. The method includes the following steps and contents:

[0025] (1) The carbon and nitrogen source can be monoamine, dicyandiamine, melamine, urea or thiourea, etc.

[0026] (2) The carbon and nitrogen source was placed in a ceramic boat and calcined in an air atmosphere in a tube furnace at a temperature of 300-1000℃ to obtain g-C3N4 nanosheets.

[0027] (3) Aniline was dispersed in 0.05-0.5 mol / L HCl solution, and an appropriate amount of ammonium persulfate and g-C3N4 nanosheets were added to the above mixture. The mixture was stirred continuously under an ice bath to obtain g-C3N4-PANI.

[0028] (4) The nickel source can be nickel nitrate, nickel chloride, nickel sulfate, nickel bromide or nickel hydroxyl, etc., and the sulfur source can be thiourea, thioacetamide, cysteine, etc. The g-C3N4-PANI is ultrasonically dispersed in deionized water, and the nickel source, sulfur source and appropriate amount of triethanolamine are added in sequence. The suspension is ultrasonically dispersed to obtain a uniformly dispersed suspension. The suspension is irradiated with a xenon lamp at room temperature in a photocatalytic reactor, collected and dried at 80°C to obtain the g-C3N4-PANI-NiS composite photocatalyst.

[0029] In summary, this technology can be used to obtain high-performance g-C3N4-PANI-NiS composite photocatalysts.

[0030] Example 1: 20g of urea was weighed and placed in a covered ceramic crucible. The crucible was heated to 550℃ in a muffle furnace at a heating rate of 2℃ / min and held for 4 hours to obtain g-C3N4 powder. After grinding, 10g of the g-C3N4 powder was weighed, placed in a ceramic boat, and transferred to a tube furnace. The furnace was heated to 450℃ in air at a heating rate of 2℃ / min and held for 6 hours to obtain g-C3N4 nanosheets. 50μL of aniline was dispersed in 20mL of 0.1mol / L HCl solution using a pipette. 0.08g of ammonium persulfate and 5g of g-C3N4 nanosheets were then added to the mixture. The mixture was continuously stirred in an ice bath for 8 hours to obtain g-C3N4-PANI. 20mg of g-C3N4-PANI was dispersed in 4mL of deionized water and ultrasonically dispersed for 0.5 hours. Then, 1mL of 0.1M HCl was added sequentially. Ni(NO3)2·6H2O solution, 1 mL 0.1M thiourea solution, 4 mL triethanolamine were added, and the mixture was sonicated again to obtain a uniformly dispersed suspension. The suspension was transferred to a photocatalytic reactor, and after being evacuated for 30 min, the mixed solution was irradiated with a xenon lamp at room temperature for 30 min to obtain the g-C3N4-PANI-NiS composite photocatalyst.

[0031] The synthesized g-C3N4-PANI-NiS composite photocatalyst has a simple preparation process and exhibits good photocatalytic activity.

Claims

1. A method for preparing a g-C3N4-PANI-NiS heterostructure photocatalyst, characterized in that, The method includes the following steps: (1) Preparation of g-C3N4 nanosheets: The carbon and nitrogen source was placed in a covered ceramic crucible and calcined in a muffle furnace to obtain pale yellow g-C3N4 powder. The g-C3N4 powder was then placed in a ceramic boat and calcined again in an air atmosphere in a tube furnace. The synthesized sample was washed three times with deionized water and anhydrous ethanol, dried overnight in a vacuum drying oven, and then ground to obtain white g-C3N4 nanosheets. (2) Preparation of g-C3N4-PANI: Aniline was dispersed in dilute hydrochloric acid solution, and an appropriate amount of ammonium persulfate and g-C3N4 nanosheets were added to the above mixture. The mixture was continuously stirred under ice bath, and the resulting green precipitate was the product. (3) Preparation of g-C3N4-PANI-NiS: g-C3N4-PANI was ultrasonically dispersed in deionized water, and nickel source, sulfur source and appropriate amount of triethanolamine were added in sequence. The suspension was ultrasonically dispersed to obtain a uniformly dispersed suspension. The suspension was irradiated with a xenon lamp at room temperature in a photocatalytic reactor to obtain g-C3N4-PANI-NiS composite photocatalyst and dried.

2. The preparation method according to claim 1, characterized in that, In step (1), the carbon and nitrogen source is monoamine, dicyandiamine, melamine, urea or thiourea; in step (1), the first calcination temperature is 300-1000℃ and the second calcination temperature is 100-500℃; in step (2), the stirring time is 1-10h; in step (2), the concentration of dilute hydrochloric acid is 0.05-0.5mol / L; in step (3), the ultrasonic time is 0.5-2h; in step (3), the nickel source is nickel nitrate, nickel chloride, nickel sulfate, nickel bromide or nickel hydroxyl; in step (3), the sulfur source is thiourea, thioacetamide or cysteine; in step (3), the irradiation time is 10-60min; in step (3), the drying temperature is 50-80℃.

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