Bismuth/non-stoichiometric ratio Oriviris compound nano composite material and preparation method and application thereof
Technical Field
The invention belongs to the technical field of chemistry and chemical engineering, functional materials and nano materials, and particularly relates to a nano composite material of a bismuth composite non-stoichiometric ratio Olympus compound, and a preparation method and application thereof.
Background
The bismuth-based material can be widely applied to various fields such as electronic ceramic materials, electrolyte materials, photoelectric materials, sensors, microelectronic elements, high-temperature superconducting materials, catalysts, ferroelectric materials and the like due to the special physicochemical properties of the bismuth-based material, and can also be used for fireproof materials, high-refractive index glass and nuclear engineering glassGlass manufacturing, nuclear reactor fuel and the like. Of which a series of oxides of the orivivis type are attracting increasing attention, these compounds being composed of perovskites [ A ]n-1BnO3n+1]The layers and fluorite layers are alternately arranged. These orivivis-type oxides have excellent photoelectrochemical properties, and thus have attracted much attention as photocatalysts. The photocatalytic reaction of the catalyst is mainly carried out between layers, and the activity of the catalyst is changed along with the difference of ions between the layers; such as Bi2MoO6、Bi2WO6、BiVO4And the like. It is clear from the existing literature reports that the photocatalytic performance of orivivis type oxides still needs to be improved.
The non-stoichiometric compound has special optical, electric, acoustic, magnetic, force and thermal properties due to the existence of crystal defects. Therefore, the synthesis of the non-stoichiometric Oriviruses type oxide has important theoretical significance and practical value. For example, Xie et al (Journal of Alloys and Compounds,2010,503: 159-3.64Mo0.36O6.55Nanospheres. The method has complex steps and complex operation, and is not beneficial to popularization and application. And Chinese patent (application publication No. CN103418333A) discloses a Bi3.64Mo0.36O6.55A preparation method of nano particles, which obtains Bi in an aqueous phase by adjusting the pH value of a solution3.64Mo0.36O6.55Nano-particle, but phase-pure Bi3.64Mo0.36O6.55Due to the limitation of the characteristics of the photocatalyst, the utilization efficiency of photon-generated carriers is low, and higher photocatalytic activity cannot be embodied. The photoelectric property of the material can be improved by constructing the composite nano material, so that the photocatalytic property of the material can be improved. A method for improving the photocatalytic performance of a material by directionally separating photogenerated carriers through metal loading is reported in large quantity, but a Bi composite non-stoichiometric orivivis type is not generated in an alcohol phase system through NaOH regulationMethods for synthesizing oxide composites are reported.
Disclosure of Invention
The invention aims to provide a nano composite material of a bismuth composite non-stoichiometric orivitis compound, which has strong photocatalytic activity and wide application range, and the related preparation method is simple, has mild reaction conditions and strong repeatability, and is suitable for the application fields of photocatalytic degradation of organic matters and the like.
In order to achieve the purpose, the invention adopts the technical scheme that:
a nano-class composite material of bismuth-enriched non-stoichiometric orivitis compound with the chemical expression of Bi/Bi3.64Mo0.36O6.55Or Bi/Bi3.84W0.16O6.24Which is composed of non-stoichiometric ratios of Bi3.64Mo0.36O6.55Or Bi3.84W0.16O6.24The surface of the particle is deposited with metal Bi, the shape of the particle is uniform nano particles, and the average particle size is 20-30 nm.
The preparation method of the nano composite material of the bismuth composite non-stoichiometric orivitis compound comprises the following steps: dissolving and dispersing bismuth nitrate and sodium molybdate or sodium tungstate in Ethylene Glycol (EG) to be uniformly mixed to obtain a mixed solution I, then adding ethanol and alkali liquor into the obtained mixed solution I, uniformly stirring, carrying out hydrothermal reaction on the obtained reaction solution, then carrying out centrifugal washing to remove residual impurities, drying and cooling to obtain the bismuth composite non-stoichiometric orivitis compound nanocomposite.
In the scheme, the molar ratio of bismuth nitrate to sodium molybdate or bismuth nitrate to sodium tungstate is 2: 1.
In the scheme, the concentration of the bismuth nitrate in the mixed solution I is 0.1-0.5 mol/L.
In the scheme, the volume ratio of the ethylene glycol to the ethanol is (2-1): 1.
In the scheme, the alkali liquor is sodium hydroxide or potassium hydroxide solution, and the concentration of the sodium hydroxide or potassium hydroxide in the reaction solution is 0.35-0.65 mol/L.
In the scheme, the hydrothermal reaction temperature is 140-200 ℃, and the time is 10-16 h.
The invention also provides the application of the composite material in the field of degrading organic pollutants under visible light, and the synthesized bismuth composite non-stoichiometric Olympus compound nano composite material further improves the utilization efficiency of photon-generated carriers due to the small size and the directional transfer of simple substance bismuth to electrons, thereby showing excellent photocatalytic performance.
The synthesis mechanism of the invention is as follows: the invention adopts a bismuth source and a molybdenum source (or a tungsten source) with a molar ratio of 2:1, adds a proper amount of sodium hydroxide into a prepared ethanol/ethylene glycol system, and regulates the dissociation of alcohol by changing the concentration of hydroxyl in a solvent to ensure that Bi in the system3+Polymerization to form a high polymer [ BinOn]n+(ii) a Then under the condition of hydrothermal reaction, the acid radical ions of molybdenum (or tungsten) in the solution react with bismuth oxygen ions ([ Bi)nOn]n+With MoO4 -Or WO4 -Reaction), bismuth is much more molybdenum (or tungsten) and further non-stoichiometric bismuth molybdate (Bi) is formed3.64Mo0.36O6.55) Or bismuth tungstate (Bi)3.84W0.16O6.24) (ii) a In addition, the reducibility of the glycol is gradually enhanced along with the increase of the amount of the sodium hydroxide in the solution, bismuth oxygen ions in the solution are reduced and deposited on the surfaces of the formed nonstoichiometric ratio bismuth molybdate (bismuth tungstate) particles, and the Bi/Bi is obtained3.64Mo0.36O6.55Or Bi/Bi3.84W0.16O6.24And (3) nanoparticles.
The beneficial results of the invention are:
1) this patent proposes and synthesizes for the first time to obtain Bi/Bi3.64Mo0.36O6.55And Bi/Bi3.84W0.16O6.24The two nano composite materials have uniform appearance and smaller particle size, and the defects of uneven appearance or wider particle size distribution of nano particles obtained by the existing method are overcome.
2) The method adopts a solvothermal synthesis process, takes alcohol as a solvent and a reducing agent, regulates the reducibility of the obtained reaction system through alkali, does not need to additionally add reducing substances, surfactants and the like, avoids secondary pollution, simplifies the synthesis process, effectively reduces the production cost, is green and environment-friendly, and can realize large-scale production of products.
Drawings
Fig. 1 is an XRD pattern of the nanocomposite of the bismuth composite non-stoichiometric orivitis compound obtained in example 1.
Fig. 2 is an SEM image of the nanocomposite of the bismuth composite non-stoichiometric orivitis compound obtained in example 1.
Fig. 3 is a TEM image of a nanocomposite of bismuth composite non-stoichiometric orivitis compound obtained in example 1.
Fig. 4 is an XRD pattern of the nanocomposite of the bismuth composite non-stoichiometric orivitis compound obtained in example 2.
Fig. 5 is a solid uv-vis diffuse reflectance spectrum of the nanocomposite of bismuth composite non-stoichiometric orivitis compound obtained in example 2.
Fig. 6 is an XRD pattern of the nanocomposite of the bismuth composite non-stoichiometric orivitis compound obtained in example 5.
Fig. 7 is an SEM image of the nanocomposite of the bismuth composite non-stoichiometric orivitis compound obtained in example 5.
FIG. 8 is a graph comparing the performance of the nanocomposites of bismuth composite non-stoichiometric Oriviris compounds obtained in example 2 with the photocatalytic degradation of bisphenol A of single-component non-stoichiometric bismuth molybdate.
Detailed Description
The invention will be further described with reference to examples and drawings, but the scope of the invention as claimed is not limited to the examples shown.
Example 1
A bismuth/non-stoichiometric orivitis compound nano composite material is prepared by the following steps:
dissolving 4mmol of bismuth nitrate pentahydrate and 2mmol of sodium molybdateUltrasonically dispersing uniformly in 20mL of Ethylene Glycol (EG), then placing the obtained solution on a stirrer, adding 20mL of ethanol and 10mL of sodium hydroxide (2mol/L) into the mixed solution while stirring, stirring for 30min, uniformly mixing, then placing the obtained reaction solution in a reaction kettle, reacting at 160 ℃ for 12h, cooling to room temperature, centrifugally washing the obtained product to remove residual impurities, drying at 60 ℃ for 12h, and cooling to obtain bismuth molybdate (Bi/Bi) with a bismuth/nonstoichiometric ratio3.64Mo0.36O6.55) A nanocomposite material.
The product obtained in this example was subjected to X-ray diffraction analysis using an X-ray diffraction analyzer (XRD) model Bruker axs D8, and the results are shown in FIG. 1. Comparison of standard cards PDF #85-1330(Bi) and PDF #43-446 (Bi)3.64Mo0.36O6.55) From the graph, the product obtained in example 1 is Bi/Bi3.64Mo0.36O6.55A nanocomposite; and no other impurity peak appears, which indicates that the obtained product is Bi/Bi with high purity3.64Mo0.36O6.55A nanocomposite material.
FIG. 2 is an SEM photograph of the product obtained in this example, as observed by a Hitachi S4800 type Scanning Electron Microscope (SEM). As can be seen from FIG. 2, Bi/Bi3.64Mo0.36O6.55The nano composite material is nano small particles, and the synthesized material has uniform appearance and average particle size of about 20 nm.
FIG. 3 is a TEM image of the product obtained in this example, which is observed by a Transmission Electron Microscope (TEM) of Philips TecnaiG2 type, and it can be seen from FIG. 3(a) that the synthesized material is nanoparticles with uniform size and good dispersity, and the particle diameter is about 20 nm. As can be seen from the electron selective area diffraction pattern in fig. 3(b), the synthesized non-stoichiometric bismuth molybdate has a polycrystalline structure, and it can be clearly seen that elemental bismuth and the grain boundary of the non-stoichiometric bismuth molybdate are in contact.
Example 2
A bismuth/non-stoichiometric orivitis compound nano composite material is prepared by the following steps:
4mmol of bismuth nitrate pentahydrate and 2mmol of molybdenumDissolving sodium in 20mL of Ethylene Glycol (EG), uniformly dispersing by ultrasonic wave, then placing the obtained solution on a stirrer, adding 10mL of ethanol and 8mL of sodium hydroxide (2mol/L) into the mixed solution while stirring, uniformly mixing by stirring for 30min, then placing the obtained reaction solution in a reaction kettle, reacting at 160 ℃ for 14h, cooling to room temperature, centrifugally washing the obtained product to remove residual impurities, drying at 60 ℃ for 12h, and cooling to obtain bismuth molybdate (Bi/Bi) with bismuth/nonstoichiometric ratio3.64Mo0.36O6.55) A nanocomposite material.
FIG. 4 is an XRD pattern obtained from the product of this example tested using a Bruker axs model D8X-ray diffraction analyser (XRD). As can be seen from the graph, the product obtained in the example is Bi/Bi3.64Mo0.36O6.55A nanocomposite material. And no other impurity peak appears, which indicates that the obtained product is Bi/Bi with high purity3.64Mo0.36O6.55A nanocomposite material.
FIG. 5 is a solid UV-visible diffuse reflectance spectrum of the product obtained in this example. As shown in the figure, the obtained Bi/Bi3.64Mo0.36O6.55Relative to Bi3.64Mo0.36O6.55The absorption range of (A) is remarkably widened.
Example 3
A bismuth/non-stoichiometric orivitis compound nano composite material is prepared by the following steps:
dissolving 2mmol of bismuth nitrate pentahydrate and 1mmol of sodium molybdate in 10mL of Ethylene Glycol (EG), ultrasonically dispersing uniformly, then placing the obtained solution on a stirrer, adding 10mL of ethanol and 2mL of potassium hydroxide (4mol/L) into the mixed solution while stirring, stirring for 30min, uniformly mixing, then placing the obtained reaction solution in a reaction kettle, reacting for 16h at 140 ℃, cooling to room temperature, centrifugally washing the obtained product to remove residual impurities, drying at 60 ℃ for 12h, and cooling to obtain bismuth/non-stoichiometric ratio bismuth molybdate (Bi/Bi)3.64Mo0.36O6.55) A nanocomposite material.
Example 4
A bismuth/non-stoichiometric orivitis compound nano composite material is prepared by the following steps:
dissolving 2mmol of bismuth nitrate pentahydrate and 1mmol of sodium molybdate in 20mL of Ethylene Glycol (EG), ultrasonically dispersing uniformly, then placing the obtained solution on a stirrer, adding 20mL of ethanol and 13mL of potassium hydroxide (2mol/L) into the mixed solution while stirring, stirring for 30min, uniformly mixing, then placing the obtained reaction solution in a reaction kettle, reacting for 10h at 200 ℃, cooling to room temperature, centrifugally washing the obtained product to remove residual impurities, drying at 60 ℃ for 12h, and cooling to obtain bismuth/non-stoichiometric ratio bismuth molybdate (Bi/Bi)3.64Mo0.36O6.55) A nanocomposite material.
Example 5
A bismuth/non-stoichiometric orivitis compound nano composite material is prepared by the following steps:
dissolving 4mmol of bismuth nitrate pentahydrate and 2mmol of sodium tungstate in 20mL of Ethylene Glycol (EG), ultrasonically dispersing uniformly, then placing the obtained solution on a stirrer, adding 10mL of ethanol and 8mL of sodium hydroxide (2mol/L) into the mixed solution while stirring, stirring for 30min, uniformly mixing, then placing the obtained reaction solution in a reaction kettle, reacting for 12h at 160 ℃, cooling to room temperature, centrifugally washing the obtained product to remove residual impurities, drying at 60 ℃ for 12h, and cooling to obtain bismuth tungstate (Bi/Bi) with bismuth non-stoichiometric ratio (Bi/Bi)3.84W0.16O6.24) A nanocomposite material.
FIG. 6 is an XRD pattern obtained from the product of this example tested using a Bruker axs D8 model X-ray diffraction analyser (XRD). Comparing standard cards PDF #85-1330(Bi) and PDF #43-447 (Bi)3.84W0.16O6.24) As can be seen from the graph, the product obtained by the method is Bi/Bi3.84W0.16O6.24The nano composite material has no other impurity peaks, and the obtained product is high-purity bismuth oxide.
FIG. 7 is an SEM image of the product obtained in the present example, as observed by a Hitachi S4800 type Scanning Electron Microscope (SEM). As can be seen from FIG. 7, Bi/Bi3.64Mo0.36O6.55Nanocomposite materialIs nano-sized particles, and the synthesized material has uniform appearance and average particle size of about 20 nm.
Example 6
A bismuth/non-stoichiometric orivitis compound nano composite material is prepared by the following steps:
dissolving 2mmol of bismuth nitrate pentahydrate and 1mmol of sodium tungstate in 10mL of Ethylene Glycol (EG), ultrasonically dispersing uniformly, then placing the obtained solution on a stirrer, adding 10mL of ethanol and 6mL of sodium hydroxide (2mol/L) into the mixed solution while stirring, stirring for 30min, uniformly mixing, then placing the obtained reaction solution in a reaction kettle, reacting for 14h at 180 ℃, cooling to room temperature, centrifugally washing the obtained product to remove residual impurities, drying at 60 ℃ for 12h, and cooling to obtain bismuth tungstate (Bi/Bi) with bismuth non-stoichiometric ratio3.84W0.16O6.24) A nanocomposite material.
Application example
The bismuth/nonstoichiometric ratio of bismuth molybdate (Bi/Bi) obtained in example 23.64Mo0.36O6.55) The nano composite material is subjected to a photocatalytic degradation bisphenol A performance test, and the specific steps are as follows:
0.02g of the product obtained in example 2 was weighed out and dispersed in 40mg/L bisphenol A solution, and the solution was magnetically stirred in the dark for half an hour to reach the equilibrium of adsorption and desorption. Then, a 300W xenon lamp (UV light below 400nm was filtered off with a filter) was turned on, and 2ml of the suspension was removed with a dropper at intervals. And after centrifugation, taking the supernatant into a quartz cuvette, and analyzing the absorbance change of the bisphenol A in an ultraviolet-visible spectrophotometer so as to represent the degradation effect of the bisphenol A. The degradation rate is calculated by the formula (A)0-A)/A0×100%(A0-raw absorbance; a-absorbance after degradation). FIG. 8 is a graph showing the nonstoichiometric ratio of bismuth molybdate (Bi/Bi) in which bismuth was complexed as obtained in example 23.64Mo0.36O6.55) Comparison of the Properties of the nanomaterials and Single component bismuth molybdate for the photocatalytic degradation of bisphenol A by visible light, it can be seen that the bismuth-complexed bismuth molybdate (Bi/Bi) obtained in example 23.64Mo0.36O6.55) Nano materialThe bisphenol A can be degraded by 80% in 4h, and the degradation rate of the single-component non-stoichiometric bismuth molybdate to the bisphenol A in 4h is less than 20%. FIG. 8 shows that the bismuth-complexed non-stoichiometric bismuth molybdate (Bi/Bi) obtained by the method of the present invention3.64Mo0.36O6.55) The degradation efficiency of the nano composite material for photocatalytic degradation of bisphenol A is obviously superior to that of single-component bismuth molybdate with non-stoichiometric ratio.
It is to be understood that the organic contaminants described herein are not limited to bisphenol a.
The preparation method of the single-component non-stoichiometric bismuth molybdate comprises the following steps: dissolving 2mmol of bismuth nitrate pentahydrate and 1mmol of sodium molybdate in 20mL of Ethylene Glycol (EG), ultrasonically dispersing uniformly, then placing the obtained solution on a stirrer, adding 20mL of ethanol and 6mL of sodium hydroxide (2mol/L) into the mixed solution while stirring, stirring for 30min, uniformly mixing, then placing the obtained reaction solution in a reaction kettle, reacting for 12h at 160 ℃, cooling to room temperature, centrifugally washing the obtained product to remove residual impurities, drying at 60 ℃ for 12h, and cooling to obtain the non-stoichiometric bismuth molybdate (Bi)3.64Mo0.36O6.55)。
It should be noted that the above-mentioned preferred embodiments illustrate rather than limit the invention, and that, although the invention has been described in detail with reference to the above-mentioned preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention as defined by the appended claims.