A novel bifunctional phosphate-modulated nanorod heterojunction photocatalyst and a preparation method thereof

Abstract

The application discloses a novel bifunctional phosphate-modulated Cu2O / CeO2 nanorod heterojunction photocatalyst and a preparation method thereof. The photocatalyst is prepared by using cerium nitrate hexahydrate and copper sulfate pentahydrate as raw materials, sodium hypophosphite and ethylene glycol as polar solvents, and adopting a heating stirring-centrifugation assisted method. The microstructure of the prepared Cu2O / CeO2 nanorod heterojunction photocatalyst is a rod structure, and the surface of the photocatalyst contains rich functional groups. The Cu2O / CeO2 composite material is prepared by adopting a conventional wet chemical method, and different Cu2O proportions are used to construct the phosphate-modulated Cu2O / CeO2 heterojunction. The Cu2O / CeO2 nanorod heterojunction photocatalyst prepared by the method has excellent photocatalytic hydrogen production activity under visible light.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor photocatalysis, specifically relating to a novel bifunctional phosphate-modulated Cu2O / CeO2 nanorod heterojunction photocatalyst and its preparation method. Technical Background

[0002] The world today faces the severe challenges of dwindling fossil fuel resources and escalating environmental pollution. Developing renewable and clean energy has become a crucial issue related to human survival and sustainable development. Hydrogen energy, as a secondary energy source, is considered one of the most ideal green energy sources. The International Hydrogen Energy Agency (IEA) predicts that with the development of hydrogen production, storage, and utilization technologies, hydrogen energy will occupy a vital position in the global energy mix by 2050, ushering in a "hydrogen economy" era for the world economy. Currently, among mature hydrogen production technologies, fossil fuel-based hydrogen production cannot fundamentally solve the energy shortage and environmental pollution problems; water electrolysis for hydrogen production is costly; and high-temperature pyrolysis of water for hydrogen production has low energy conversion efficiency, making it difficult to develop into a viable energy hydrogen production technology. Therefore, developing clean, efficient, and low-cost hydrogen production technologies has significant social and economic implications.

[0003] Among semiconductor materials, CdS has a band gap of 2.4 eV (~516 nm), making it one of the most promising materials for detecting visible light radiation. It is considered an important material in optoelectronic fields, such as optical displays, solar cells, light-emitting diodes, and transistors. Beyond these applications, it has also created a new research hotspot in the field of visible light-driven photocatalysis. As is well known, photocatalysis is a surface-catalyzed reaction, strongly influenced by variations in the shape, size, and morphology of the catalyst. Therefore, various attempts have been explored to fabricate 1D to 3D CdS nanostructured photocatalysts using different methods, such as colloidal methods, hydrothermal / solvothermal methods, laser growth processes, template-based electrochemically induced deposition, and thermal evaporation. However, research on morphology control and its impact on photocatalytic performance within the same system is scarce, especially regarding the large-scale preparation of uniform CdS nanosphere photocatalysts under mild conditions, which still presents numerous challenges. Summary of the Invention

[0004] To address the problems existing in the background technology, the present invention provides a novel bifunctional phosphate-modulated nanorod heterojunction photocatalyst and its preparation method.

[0005] The present invention specifically adopts the following technical solution:

[0006] A novel method for preparing bifunctional phosphate-modified nanorod heterojunction photocatalysts is described, which uses cerium nitrate hexahydrate and copper sulfate pentahydrate as raw materials, sodium hypophosphite and ethylene glycol as polar solvents, and employs a heating-stirring-centrifugation assisted method.

[0007] Furthermore, the preparation method of the novel bifunctional phosphate-modulated nanorod heterojunction photocatalyst includes the following steps:

[0008] (1) Dissolve cerium nitrate hexahydrate in deionized water, combine it with sodium hydroxide, heat the resulting solution in a hydrothermal steel reactor at a certain temperature for a period of time, wash and dry the precipitate, and calcine it in a muffle furnace at a certain temperature for a period of time.

[0009] (2) Then, a certain amount of copper sulfate pentahydrate and sodium hypophosphite were added to water and dissolved using a magnetic stirrer. Then, sodium hydroxide solution was added and stirred at the same time. After stirring for a certain period of time, ethylene glycol was added and heated for a period of time. Then, the cuprous oxide nanorods were centrifuged, washed with alcohol, and dried in a vacuum.

[0010] (3) Then a certain amount of Cu2O / CeO2 is dispersed into a certain amount of deionized water / anhydrous ethanol, stirred for a period of time, and then the mixture is dried in a water bath while being stirred continuously.

[0011] (4) Then, different amounts of phosphoric acid were added to the dispersion mixture of cerium oxide, stirred in ethanol solution for a period of time, and then different proportions of cuprous oxide were used to construct novel bifunctional phosphate-modified Cu2O / CeO2 nanorod heterojunction photocatalysts.

[0012] Furthermore, the heating time in the hydrothermal steel reactor at a certain temperature mentioned in step (1) is 20 to 24 hours at a temperature of 120°C to 150°C.

[0013] Furthermore, the calcination in the muffle furnace at a certain temperature mentioned in step (1) is carried out for 3 to 4 hours at a muffle furnace at a temperature of 500°C to 600°C.

[0014] Further, in step (2), 0.125g of copper sulfate pentahydrate and 0.12g of sodium hypophosphite are dissolved in 10mL of water for 10 minutes using a magnetic stirrer to achieve complete dissolution.

[0015] Further, in step (2), 10-15 mL of 0.15 M NaOH is gradually added to the solution, and after stirring for 15-20 minutes, 20-30 mL of ethylene glycol is added. The suspension is then heated statically for 3-4 hours to 65-75°C.

[0016] Further, in step (2), the produced Cu2O nanorods are centrifuged, washed with anhydrous alcohol, and dried in a vacuum at 40°C for 6–7 hours.

[0017] Further, in step (3), a certain amount of Cu2O and 1.0g CeO2 are dispersed in 50mL / 50mL~70mL of deionized water / anhydrous ethanol. The Cu2O and CeO2 dispersion mixture is magnetically stirred for 18~24 hours. Then the mixture is dried in a water bath while being continuously stirred with a magnetic stirrer at a temperature <80℃.

[0018] Further, in step (4), different amounts of phosphoric acid are added to a dispersion mixture of 0.5g CeO2, and stirred in 50mL to 75mL of ethanol for 10 to 12 hours to obtain phosphate-modified CeO2 (yP-CeO2); then, novel bifunctional phosphate-modified Cu2O / CeO2 nanorod heterojunction photocatalysts are constructed using different Cu2O ratios.

[0019] The present invention has the following beneficial effects:

[0020] In this invention, cerium nitrate hexahydrate and copper sulfate pentahydrate are used as raw materials, and sodium hypophosphite and ethylene glycol are used as polar solvents, employing a heating-stirring-centrifugation assisted method. The sodium hypophosphite and ethylene glycol mixture acts as polar solvents to adjust the solvent polarity during the reaction process. The use of cerium nitrate hexahydrate and copper sulfate pentahydrate as raw materials facilitates the decomposition to generate copper and cerium ions. The vacuum condition prevents oxidation during the preparation of Cu₂O / CeO₂ nanorods, removes dissolved oxygen from the solvent, reduces interfacial partial pressure, and lowers the surface tension of solvent molecules. The stirring process ensures thorough mixing of the reactants, guaranteeing uniform distribution of the reactants in the reaction system, while also preventing product precipitation and maintaining temperature uniformity within the reaction system. Attached Figure Description

[0021] Figure 1 This is a transmission electron microscope (TEM) image of the Cu2O / CeO2 nanorod heterojunction photocatalyst prepared in Example 1 of this invention.

[0022] Figure 2 The image shows the XRD pattern of the Cu2O / CeO2 nanorod heterojunction photocatalyst prepared in Example 1 of this invention.

[0023] Figure 3 The fluorescence spectrum and electrochemical impedance spectroscopy of the Cu2O / CeO2 nanorod heterojunction photocatalyst prepared in Example 1 of this invention are shown.

[0024] Figure 4 This is a graph showing the photocatalytic activity of the Cu2O / CeO2 nanorod heterojunction photocatalyst prepared in Example 1 of this invention under light irradiation to evaluate CO2 conversion. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0026] Example 1

[0027] A method for preparing a novel bifunctional phosphate-modified Cu2O / CeO2 nanorod heterojunction photocatalyst includes the following steps:

[0028] (1) Dissolve cerium nitrate hexahydrate in deionized water, combine it with sodium hydroxide, heat the resulting solution in a hydrothermal steel reactor at 120°C for 20 hours, wash and dry the precipitate, and calcine it in a muffle furnace at 500°C for 3 hours.

[0029] (2) Then, 0.125 g of copper sulfate pentahydrate and 0.12 g of sodium hypophosphite were dissolved in water using a magnetic stirrer. Then, 15 mL of sodium hydroxide solution was added and stirred at the same time. After stirring for 20 min, 25 mL of ethylene glycol was added and heated for 4 hours. Then, the cuprous oxide nanorods were centrifuged, washed with alcohol, and dried in a vacuum.

[0030] (3) Then a certain amount of Cu2O / CeO2 was dispersed into 50 mL of deionized water / anhydrous ethanol and stirred for 18 hours. The mixture was then dried in a water bath while being stirred continuously at 70°C.

[0031] (4) Then, different amounts of phosphoric acid were added to the dispersion mixture of cerium oxide, and the mixture was stirred in 50 mL of ethanol solution for 10 hours. Then, novel bifunctional phosphate-modified Cu2O / CeO2 nanorod heterojunction photocatalysts were constructed using cuprous oxide in different ratios of 1:2, 1:4, 1:6, and 1:8.

[0032] Figure 1-4 The characterization results of the Cu2O / CeO2 nanorod heterojunction photocatalyst prepared in Example 1 are as follows:

[0033] Figure 1 The image shows a transmission electron microscope (TEM) image of the Cu2O / CeO2 nanorod heterojunction photocatalyst prepared in Example 1 of this invention. As can be seen from the image, CeO2 exhibits a rod-like structure, with Cu2O particles loaded on the surface of the CeO2 rod-like structure, thus demonstrating a Cu2O / CeO2 composite heterojunction.

[0034] Figure 2 The image shows the XRD pattern of the Cu2O / CeO2 nanorod heterojunction photocatalyst prepared in Example 1 of this invention. As can be seen from the image, the XRD pattern of the Cu2O / CeO2 nanorod heterojunction mainly shows the diffraction peak of CeO2, while the diffraction peak of Cu2O is weaker, which is mainly due to the low surface loading of Cu2O.

[0035] Figure 3 The fluorescence spectrum and electrochemical impedance spectroscopy of the Cu2O / CeO2 nanorod heterojunction photocatalyst prepared in Example 1 of this invention are shown in the figure. As can be seen from the figure, the 6Cu2O / 6P-CeO2 sample shows the lowest fluorescence intensity and the smallest electrochemical impedance value, indicating that the 6Cu2O / 6P-CeO2 sample has excellent separation and migration efficiency of photogenerated electron-hole pairs.

[0036] Figure 4 This figure shows the photocatalytic activity of the Cu2O / CeO2 nanorod heterojunction photocatalyst prepared in Example 1 of this invention under light irradiation to evaluate CO2 conversion. As can be seen from the figure, the photocatalytic CO2 reduction products of all samples are methane and carbon monoxide, with no other products generated. Compared with other samples, the 6Cu2O / 6P-CeO2 sample exhibits the highest photocatalytic performance.

[0037] Example 2

[0038] A method for preparing a novel bifunctional phosphate-modified Cu2O / CeO2 nanorod heterojunction photocatalyst includes the following steps:

[0039] (1) Dissolve cerium nitrate hexahydrate in deionized water, combine it with sodium hydroxide, heat the resulting solution in a hydrothermal steel reactor at 150°C for 20 hours, wash and dry the precipitate, and calcine it in a muffle furnace at 600°C for 3 hours.

[0040] (2) Then, 0.125 g of copper sulfate pentahydrate and 0.12 g of sodium hypophosphite were dissolved in water using a magnetic stirrer. Then, 15 mL of sodium hydroxide solution was added and stirred at the same time. After stirring for 20 min, 25 mL of ethylene glycol was added and heated for 4 hours. Then, the cuprous oxide nanorods were centrifuged, washed with alcohol, and dried in a vacuum.

[0041] (3) Then a certain amount of Cu2O / CeO2 was dispersed into 50 mL of deionized water / anhydrous ethanol and stirred for 18 hours. The mixture was then dried in a water bath while being stirred continuously at 70°C.

[0042] (4) Then, different amounts of phosphoric acid were added to the dispersion mixture of cerium oxide, and the mixture was stirred in 50 mL of ethanol solution for 10 hours. Then, novel bifunctional phosphate-modified Cu2O / CeO2 nanorod heterojunction photocatalysts were constructed using cuprous oxide in different ratios of 1:2, 1:4, 1:6, and 1:8.

[0043] Example 3

[0044] A method for preparing a novel bifunctional phosphate-modified Cu2O / CeO2 nanorod heterojunction photocatalyst includes the following steps:

[0045] (1) Dissolve cerium nitrate hexahydrate in deionized water, combine it with sodium hydroxide, heat the resulting solution in a hydrothermal steel reactor at 120°C for 24 hours, wash and dry the precipitate, and calcine it in a muffle furnace at 500°C for 4 hours.

[0046] (2) Then, 0.125 g of copper sulfate pentahydrate and 0.12 g of sodium hypophosphite were dissolved in water using a magnetic stirrer. Then, 15 mL of sodium hydroxide solution was added and stirred at the same time. After stirring for 20 min, 25 mL of ethylene glycol was added and heated for 4 hours. Then, the cuprous oxide nanorods were centrifuged, washed with alcohol, and dried in a vacuum.

[0047] (3) Then a certain amount of Cu2O / CeO2 was dispersed into 50 mL of deionized water / anhydrous ethanol and stirred for 18 hours. The mixture was then dried in a water bath while being stirred continuously at 70°C.

[0048] (4) Then, different amounts of phosphoric acid were added to the dispersion mixture of cerium oxide, and the mixture was stirred in 50 mL of ethanol solution for 10 hours. Then, novel bifunctional phosphate-modified Cu2O / CeO2 nanorod heterojunction photocatalysts were constructed using cuprous oxide in different ratios of 1:2, 1:4, 1:6, and 1:8.

[0049] Comparative Example 1

[0050] A method for preparing a nanorod heterojunction photocatalyst includes the following steps:

[0051] (1) Dissolve cerium nitrate hexahydrate in deionized water, combine it with sodium hydroxide, heat the resulting solution in a hydrothermal steel reactor at 120°C for 20 hours, wash and dry the precipitate, and calcine it in a muffle furnace at 550°C for 3 hours.

[0052] (2) Then, 0.125 g of copper sulfate pentahydrate and 0.12 g of sodium hypophosphite were dissolved in water using a magnetic stirrer. Then, 10 mL of sodium hydroxide solution was added and stirred at the same time. After stirring for 15 min, 20 mL of ethylene glycol was added and heated for 4 hours. Then, the cuprous oxide nanorods were centrifuged, washed with alcohol, and dried in a vacuum.

[0053] (3) Then a certain amount of Cu2O / CeO2 was dispersed into 50 mL of deionized water / anhydrous ethanol and stirred for 18 hours. The mixture was then dried in a water bath while being stirred continuously at 70°C.

[0054] (4) Then, different amounts of phosphoric acid were added to the dispersion mixture of cerium oxide, and the mixture was stirred in 50 mL of ethanol solution for 10 hours. Then, phosphate-modified Cu2O / CeO2 heterojunctions were constructed using cuprous oxide in different ratios of 1:2, 1:4, 1:6, and 1:8.

[0055] Comparative Example 2

[0056] A method for preparing a nanorod heterojunction photocatalyst includes the following steps:

[0057] (1) Dissolve cerium nitrate hexahydrate in deionized water, combine it with sodium hydroxide, heat the resulting solution in a hydrothermal steel reactor at 120°C for 20 hours, wash and dry the precipitate, and calcine it in a muffle furnace at 500°C for 3 hours.

[0058] (2) Then, 0.125 g of copper sulfate pentahydrate and 0.12 g of sodium hypophosphite were dissolved in water using a magnetic stirrer. Then, 15 mL of sodium hydroxide solution was added and stirred at the same time. After stirring for 20 min, 25 mL of ethylene glycol was added and heated for 4 hours. Then, the cuprous oxide nanorods were centrifuged, washed with alcohol, and dried in a vacuum.

[0059] (3) Then a certain amount of Cu2O / CeO2 is dispersed into 70 mL of deionized water / anhydrous ethanol and stirred for 24 hours. The mixture is then dried in a water bath while being stirred continuously at 80 °C.

[0060] (4) Then, different amounts of phosphoric acid were added to the dispersion mixture of cerium oxide, and the mixture was stirred in 50 mL of ethanol solution for 10 hours. Then, phosphate-modified Cu2O / CeO2 heterojunctions were constructed using cuprous oxide in different ratios of 1:2, 1:4, 1:6, and 1:8.

[0061] Comparative Example 3

[0062] A method for preparing a nanorod heterojunction photocatalyst includes the following steps:

[0063] (1) Dissolve cerium nitrate hexahydrate in deionized water, combine it with sodium hydroxide, heat the resulting solution in a hydrothermal steel reactor at 120°C for 20 hours, wash and dry the precipitate, and calcine it in a muffle furnace at 500°C for 3 hours.

[0064] (2) Then, 0.125 g of copper sulfate pentahydrate and 0.12 g of sodium hypophosphite were dissolved in water using a magnetic stirrer. Then, 15 mL of sodium hydroxide solution was added and stirred at the same time. After stirring for 20 min, 25 mL of ethylene glycol was added and heated for 4 hours. Then, the cuprous oxide nanorods were centrifuged, washed with alcohol, and dried in a vacuum.

[0065] (3) Then a certain amount of Cu2O / CeO2 was dispersed into 50 mL of deionized water / anhydrous ethanol and stirred for 18 hours. The mixture was then dried in a water bath while being stirred continuously at 70°C.

[0066] (4) Then, different amounts of phosphoric acid were added to the dispersion mixture of cerium oxide and stirred in 75 mL of ethanol solution for 12 hours. Then, phosphate-modified Cu2O / CeO2 heterojunctions were constructed using cuprous oxide in different ratios of 1:2, 1:4, 1:6, and 1:8.

[0067] The above description is only for understanding the method and core idea of ​​the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

Claims

1. A method for preparing a bifunctional phosphate-modulated nanorod heterojunction photocatalyst, characterized in that: Includes the following steps: (1) Dissolve cerium nitrate hexahydrate in deionized water, combine it with sodium hydroxide, heat the resulting solution in a hydrothermal steel reactor at a certain temperature for a period of time, wash and dry the precipitate, and calcine it in a muffle furnace at a certain temperature for a period of time. (2) Then, a certain amount of copper sulfate pentahydrate and sodium hypophosphite were added to water and dissolved using a magnetic stirrer. Then, sodium hydroxide solution was added and stirred at the same time. After stirring for a certain period of time, ethylene glycol was added and heated for a period of time. Then, the cuprous oxide nanorods were centrifuged, washed with alcohol, and dried in a vacuum. (3) Then a certain amount of Cu2O and CeO2 are dispersed into a certain amount of deionized water / anhydrous ethanol, stirred for a period of time, and then the mixture is dried in a water bath while being stirred continuously. (4) Then, different amounts of phosphoric acid were added to the dispersion mixture of cerium oxide, stirred in ethanol solution for a period of time, and then bifunctional phosphate-modified Cu2O / CeO2 nanorod heterojunction photocatalysts were constructed using different proportions of cuprous oxide. The heating time in the hydrothermal steel reactor at a certain temperature mentioned in step (1) is 20 to 24 hours at a temperature of 120℃ to 150℃. The calcination in a muffle furnace at a certain temperature mentioned in step (1) is calcination in a muffle furnace at 500℃~600℃ for 3~4 hours; In step (2), 10-15 mL of 0.15 M NaOH is gradually added to the solution. After stirring for 15-20 minutes, 20-30 mL of ethylene glycol is added, and the suspension is heated statically for 3-4 hours to 65-75°C.

2. The method for preparing the bifunctional phosphate-modified nanorod heterojunction photocatalyst according to claim 1, characterized in that, In step (2), 0.125 g of copper sulfate pentahydrate and 0.12 g of sodium hypophosphite are dissolved in 10 mL of water for 10 minutes using a magnetic stirrer to achieve complete dissolution.

3. The method for preparing the bifunctional phosphate-modified nanorod heterojunction photocatalyst according to claim 1, characterized in that, In step (2), the produced Cu2O nanorods are centrifuged, washed with anhydrous alcohol, and dried in a vacuum at 40°C for 6-7 hours.

4. A bifunctional phosphate-modulated Cu2O / CeO2 nanorod heterojunction photocatalyst prepared by the method according to any one of claims 1 to 3.

Images