CN112723409B

CN112723409B - SrTiO3Method for preparing polyhedron

Info

Publication number: CN112723409B
Application number: CN202011237201.5A
Authority: CN
Inventors: 朱小鹏; 陆磊; 程瑜; 宋若飞; 乔冠军
Original assignee: Jiangsu University
Current assignee: Jiangsu University
Priority date: 2020-11-09
Filing date: 2020-11-09
Publication date: 2022-04-26
Anticipated expiration: 2040-11-09
Also published as: CN112723409A

Abstract

The invention belongs to the field of inorganic non-metallic materials, and particularly relates to SrTiO₃A preparation method of polyhedron. The invention takes strontium hydroxide and titanium dioxide as raw materials, sodium chloride and bicarbonateSodium is a molten salt. The method comprises the following steps: (1) mixing strontium hydroxide and titanium dioxide raw materials with sodium chloride and sodium bicarbonate composite molten salt; (2) carrying out wet grinding and drying treatment on the obtained mixed material; (3) reacting the obtained powder particles at 700-900 ℃ for 5-10 h; (4) washing and drying the obtained product to finally obtain SrTiO with high crystallinity, good dispersity and jointly exposed crystal faces of (001) and (110)₃Polyhedral powder material. The method has simple operation steps, no other by-products, mass preparation and convenient industrial production.

Description

SrTiO3Method for preparing polyhedron

Technical Field

The invention belongs to the field of inorganic non-metallic materials, and particularly relates to SrTiO₃A preparation method of polyhedron.

Background

SrTiO₃Is typically of perovskite (ABO)₃Type) structure, which has a high dielectric constant and low dielectric loss, good piezoelectric properties, ferroelectricity and thermal stability, and a suitable optical forbidden bandwidth and energy band structure, has wide and important applications in the fields of electronic devices, industrial ceramics, energy sources, catalysis, and the like.

Research shows that the physical and chemical properties of the material depend greatly on the micro-morphology and structure of the material. For example, TiO₂The nano-rods, the nano-fibers and the cubes all present irregular TiO₂The particles have more excellent photoelectrochemical properties. At present, SrTiO with cubic, nanorod, micro-nano flower-shaped and other morphological structures₃Have been widely reported. With the progress of research, the physical and chemical properties of the material can be remarkably improved by regulating and controlling the specific exposed crystal face of the material and utilizing the synergistic effect between the crystal faces. The main reason for this is that the electron structures of different exposed crystal planes differ from each other due to different atomic arrangements. Typically, a semiconductor energy band presents anisotropy in a three-dimensional direction of a space, and a crystal plane electric field can be formed by changing an exposed crystal plane of a semiconductor, so that the effective separation of photo-generated electrons and holes is realized, and the photoelectric catalytic performance of the semiconductor energy band is improved. Thus, SrTiO is prepared₃The polyhedron has important significance for improving the photoelectrochemistry and other properties of the polyhedron.

Literature (Scientific Reports 2014,4, 5084; Nano Research 2014,7,1311) reported a process using TiCl₄And SrCl₂Taking organic alcohol (propylene glycol, glycerol or butanetriol) as a surfactant as a raw material, adjusting the pH of the solution by using LiOH, and hydrothermally synthesizing SrTiO₃A preparation method of the octadecahedron. However, the preparation process of the method is complex, and the TiCl serving as the reaction raw material needs to be controlled in an ice-water bath₄The dropping speed of the solution is high, meanwhile, the reaction time is long, the temperature needs to be kept at 180 ℃ for 48 hours, and organic matter residues exist on the surface of the material and need to be removed by high-temperature annealing treatment. The invention patent (publication number CN105727922B) discloses a Li-doped SrTiO₃The preparation method of the octodecahedron nano-particles comprises the steps of preparing titanium hydroxide by using titanium sulfate and potassium hydroxide, and then mixing the titanium hydroxide with strontium nitrate solution, potassium hydroxide solution and halite octahedron LiTiO₂The nano particles are stirred and mixed to carry out hydrothermal reaction. The method not only needs to use an easy-explosion reagent, but also has the dropping speed of the raw materials and the LiTiO₂The morphology has strict requirements. In addition, strontium carbonate formed by mixing carbon dioxide into the precursor needs to be removed by acetic acid cleaning.

Disclosure of Invention

Aiming at the technical problem, the invention provides SrTiO₃The simple synthesis method of the polyhedron has simple operation steps, does not need organic surfactant, strong alkali and acid washing treatment, can be prepared in large batch and is convenient for industrial production.

The invention aims to prepare SrTiO₃Polyhedral and provides a simple and effective synthesis method.

The invention takes strontium hydroxide and titanium dioxide as raw materials and sodium chloride and sodium bicarbonate as molten salt to prepare SrTiO₃High crystallinity, good dispersibility, and polyhedral structure with exposed (001) and (110) crystal faces. The method comprises the following specific steps:

(1) weighing strontium hydroxide and titanium dioxide in a stoichiometric ratio as raw materials; mixing sodium chloride and sodium bicarbonate according to the weight ratio of 3-8: 1 to obtain composite molten salt; and mixing the raw materials and the composite molten salt according to the proportion of 1: mixing at a molar ratio of 8-20 to obtain a mixture;

(2) adding an ethanol water solution or pure water into the mixture for wet grinding, and drying after the mixture is fully mixed;

(3) adding the dried powder particles into a crucible, heating to 700-900 ℃ at a heating rate of 5 ℃/min in an air atmosphere, reacting for 5-10 h, and naturally cooling to room temperature after the reaction is finished;

(4) washing the obtained product with deionized water, and drying to obtain SrTiO₃Polyhedral powder material.

Compared with the prior art, the invention has the beneficial effects that:

(1) SrTiO prepared by the invention₃The polyhedron has high crystallinity and good dispersibility;

(2) the preparation method has the advantages of simple preparation flow, low equipment requirement, low raw material cost, large-scale synthesis and easy industrial production;

(3) the invention does not need to use organic surface active agent, and has no environmental pollution.

Drawings

FIG. 1 shows SrTiO synthesized in example 1₃XRD pattern of polyhedral particles.

FIG. 2 shows SrTiO synthesized in example 1₃SEM pictures of polyhedral particles.

FIG. 3 shows SrTiO synthesized in example 2₃SEM pictures of polyhedral particles.

FIG. 4 shows SrTiO synthesized in example 3₃TEM pictures of polyhedral particles.

FIG. 5 shows SrTiO synthesized in example 4₃TEM and SAED pictures of polyhedral particles.

FIG. 6 shows SrTiO synthesized in example 4₃Polyhedral particle and SrTiO synthesized by traditional solid phase method₃Photocatalytic reduction of CO by particles₂Performance is compared to the graph.

Detailed Description

Example 1

(1) Weighing strontium hydroxide (0.304g) and titanium dioxide (0.2g) in a stoichiometric ratio; sodium chloride (1.16g) and sodium bicarbonate (0.42g) were mixed as a 4: 1 to obtain composite molten salt; and mixing the raw materials and the composite molten salt according to the proportion of 1: 10 mol ratio mixing;

(2) adding an ethanol aqueous solution into the mixture for wet grinding, and drying after the mixture is fully mixed;

(3) adding the fully dried powder particles into a crucible, heating to 700 ℃ at a heating rate of 5 ℃/min in an air atmosphere, reacting for 10h, and naturally cooling to room temperature after the reaction is finished;

FIG. 1 shows SrTiO prepared₃The polyhedron XRD pattern has all diffraction peaks corresponding to standard card JCPDS #35-0734 one by one and is pure cubic phase SrTiO₃A material. The diffraction peak intensity is high, the half-peak width is narrow, and the prepared SrTiO is illustrated₃The degree of polyhedral crystallinity is high.

FIG. 2 shows SrTiO prepared₃The crystal surface of the polyhedron SEM picture is smooth, has no obvious defects, shows good crystallinity, and SrTiO₃Has an eighteen-hedron structure, good dispersibility and particle size of 200-500 nm.

Example 2

This example is the same as example 1 except that the aqueous ethanol solution was replaced with pure water during wet ball milling.

FIG. 3 shows SrTiO prepared₃Polyhedral SEM picture, change of milling dispersant to synthetic SrTiO compared to example 1₃The polyhedral structure, dispersibility and particle size of the particles have no obvious influence.

Example 3

This example is the same as example 1 except that sodium chloride (1.74g) and sodium bicarbonate (0.42g) were weighed in 6: 1 to obtain composite molten salt; and mixing the raw materials and the composite molten salt according to the proportion of 1: and (4) mixing at a ratio of 14.

FIG. 4 shows SrTiO prepared₃Polyhedral TEM picture, SrTiO₃The polyhedral structure of (A) is not changed along with the change of process parameters, and the dispersity of particles is improved along with the increase of the proportion of molten salt.

Example 4

This example is identical to the procedure of example 1, except that the reaction temperature is 900 ℃ and the holding time is 5 hours.

FIG. 5 shows SrTiO prepared according to the present invention₃And (3) polyhedral TEM and SAED pictures, wherein the TEM picture shows a typical polyhedral structure, and shows that the change of reaction temperature and time does not influence the synthesis of SrTiO in a sodium chloride and sodium bicarbonate composite molten salt system₃Structural features of polyhedrons. SrTiO in SAED picture₃The diffraction spots are in periodic ordered lattice arrangement, which shows that the prepared SrTiO₃Is a single crystal. Obtaining the crystal face distance by taking the reciprocal after measuring the distance between the target diffraction point and the diffraction center, comparing with a standard card JCPDS #35-0734, and determining the SrTiO in the corresponding TEM picture₃The exposed crystal planes of the polyhedrons are the (001) and (110) crystal planes.

Photocatalytic reduction of CO₂And (3) performance comparison test:

0.1g of SrTiO prepared by the invention is weighed respectively₃Polyhedrons and SrTiO prepared by traditional solid-phase sintering method₃Placing the particles as photocatalyst in a photocatalytic reaction device, vacuumizing to remove oxygen-containing gaseous molecules, introducing high-purity carbon dioxide into the photocatalytic reaction device to make the pressure reach one atmosphere, adding 0.4ml of distilled water, and irradiating SrTiO with 300W xenon lamp₃Carbon dioxide reduction reaction is carried out.

FIG. 6 shows SrTiO synthesized in example 4₃Polyhedral nano-particle and SrTiO synthesized by traditional solid phase method₃Photocatalytic reduction of CO by particles₂Performance is compared to the graph. SrTiO₃Photocatalytic reduction of CO₂The products of (A) are CO and CH₄， SrTiO₃Polyhedral CO and CH₄The yield is obviously higher than that of a sample prepared by a solid phase method, and the synthesis of the polyhedron is favorable for improving SrTiO₃The photocatalytic performance of (a).

The invention has been described in detail with reference to specific embodiments and illustrative examples, but the description is not intended to be construed in a limiting sense. It will be understood by those skilled in the art that various equivalent substitutions or modifications may be made to the technical solution of the present invention and the embodiments thereof without departing from the spirit and scope of the present invention, which fall within the scope of the present invention. The scope of the invention is defined by the appended claims.

Claims

1. SrTiO₃Method for preparing polyhedron, SrTiO₃The polyhedron has a polyhedron structure with the crystal faces of (001) and (110) exposed together, and is characterized in that SrTiO is synthesized by adopting a molten salt growth method₃The method comprises the following specific steps:

(1) weighing strontium hydroxide and titanium dioxide in a stoichiometric ratio as raw materials; mixing sodium chloride and sodium bicarbonate according to a certain proportion to obtain composite molten salt; mixing the raw materials and the composite molten salt according to a certain proportion to obtain a mixture;

(2) carrying out wet grinding on the mixture obtained in the step (1), and drying after grinding and mixing uniformly;

(3) reacting the powder particles dried in the step (2) at 700-900 ℃ for 5-10 h, and naturally cooling to room temperature after the reaction is finished;

(4) washing the product obtained in the step (3) with deionized water, and drying to obtain SrTiO₃Polyhedral powder material.

2. SrTiO 2 according to claim 1₃The preparation method of the polyhedron is characterized in that in the step (1), the molar ratio of sodium chloride to sodium bicarbonate is 3-8: 1; the molar ratio of the raw materials to the composite molten salt is 1: 8 to 20.

3. SrTiO 2 according to claim 1₃The preparation method of the polyhedron is characterized in that in the step (2), the dispersing agent used in the wet grinding is ethanol water solution or pure water.

4. SrTiO 2 according to claim 1₃The preparation method of the polyhedron is characterized in that in the step (3), the temperature is raised to 700-900 ℃ at a rate of 5 ℃/min in the air atmosphere.