CN113003602B - Aluminothermic reduction cerium dioxide octahedral material and preparation method and application thereof - Google Patents

Aluminothermic reduction cerium dioxide octahedral material and preparation method and application thereof Download PDF

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CN113003602B
CN113003602B CN202110205364.3A CN202110205364A CN113003602B CN 113003602 B CN113003602 B CN 113003602B CN 202110205364 A CN202110205364 A CN 202110205364A CN 113003602 B CN113003602 B CN 113003602B
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王�琦
汪宙
李瞳
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Abstract

The invention discloses an aluminothermic reduction cerium dioxide octahedral material and a preparation method and application thereof, the material has an octahedral single crystal structure, a (111) crystal face is exposed, the surface of the octahedral single crystal structure contains oxygen vacancies, the surface of the octahedral single crystal structure is covered with an amorphous layer of 1-2 nm, and the amorphous layer contains oxygen vacancies and Ce3+. The preparation method comprises the following steps: the octahedral cerium dioxide nano-crystal is prepared by a hydrothermal method and is subjected to aluminothermic reduction treatment to obtain the octahedral cerium dioxide nano-crystal. The material provided by the invention is used for preparing an electrode, has high catalytic activity, high sensitivity, wide linear range, good stability and high selectivity, and is proved to be suitable for H in a real sample2O2Detection is carried out, the error is extremely low, and the requirements of practical application can be met.

Description

Aluminothermic reduction cerium dioxide octahedral material and preparation method and application thereof
Technical Field
The invention belongs to the technical field of electrochemical sensor manufacturing and detection analysis, and relates to an aluminothermic reduction cerium dioxide octahedron material, and a preparation method and application thereof.
Background
The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.
Crystal surface engineering can improve catalyst activity by adjusting surface electronic structure and properties, and the method is widely applied. Common surface engineering modification methods include: doping, morphology regulation, preferential exposure of active crystal faces, defect engineering, formation of surface heterojunctions and the like. Generally speaking, the optimization of the surface morphology can most directly affect the catalytic activity of the catalyst, different morphologies often determine different types and proportions of main exposed crystal faces, and different crystal faces have different surface energies and selectivities, thereby affecting the catalytic performance of the catalyst. On the other hand, during the catalytic process, the charge that reaches the catalyst surface will migrate to the atoms with lower coordination numbers, which generally act as active sites for redox reactions to occur. The defect engineering can increase the surface active center of the catalyst and introduce additional energy level so as to improve the catalytic performance. Oxygen vacancies, the most common and most widely studied surface defects, have a relatively low energy of formation at the oxide surface. The oxygen vacancy with abundant local electrons is beneficial to enhancing the adsorption and activation of reactants, reducing the energy barrier of the reaction and increasing the surface catalytic active sites.
Hydrogen peroxide (H)2O2) As a simple and common Reactive Oxygen Species (ROS), the method has important application in the fields of living of human beings such as biology, medical treatment, textile, environment, food production and the like, and strict detection and control should be carried out on the ROS. A number of methods have been developed for H2O2The enzyme-based electrochemical sensor has the advantages of high sensitivity, good selectivity, convenient detection, low cost and the like, and is widely applied to the detection of medical institutions and food. However, enzymes are very sensitive to environmental changes, especially temperature and pH, and are easily inactivated. Transition Metal Oxides (TMO) are enzyme-free H due to their unique electronic structure and excellent enzyme-like catalytic properties2O2Ideal candidate materials for electrochemical sensor electrodes. There have been some crystal plane or defect pairs H of transition metal oxides2O2The influence of the electrochemical sensing performance is not found, but the influence of the synergistic effect between the oxygen vacancy and the crystal face on the catalytic performance is not researched.
Cerium oxide (CeO)2) As a common rare earth oxide, the rare earth oxide has abundant reserves, no toxicity, harmlessness, controllable appearance and oxygen vacancy on the surface to cause Ce3+And Ce4+Coexist so that CeO2Has good catalytic performance and excellent oxidation-reduction characteristics, and is widely applied to the aspects of thermal catalysis, photocatalysis, electrocatalysis and sensors. And in the preparation of CeO2Oxygen vacancy is easily and spontaneously formed in the process, so that Ce is generated3+And Ce4+Thereby improving the oxidation-reduction capability in the catalytic process. The inventors have found that CeO is present in spite of containing a certain amount of oxygen vacancies2Possessing active sites, but CeO2The disadvantage of poor intrinsic activity also limits its large-scale application.
Disclosure of Invention
In order to solve the defects of the prior art, the invention aims to provide a thermite reduction dioxideThe cerium octahedron material provided by the invention is used for preparing an electrode, has high catalytic activity, high sensitivity, wide linear range, good stability and high selectivity, and is proved to be suitable for H in a real sample2O2Detection is carried out, the error is extremely low, and the requirements of practical application can be met.
In order to achieve the purpose, the technical scheme of the invention is as follows:
on one hand, the thermite reduction cerium dioxide octahedral material has an octahedral single crystal structure, a (111) crystal face is exposed, the surface of the octahedral single crystal structure contains oxygen vacancies, the surface of the octahedral single crystal structure is covered with an amorphous layer of 1-2 nm, and the amorphous layer contains oxygen vacancies and Ce3+。
Experiments show that compared with cerium dioxide nanocrystals with other shapes, the octahedral cerium dioxide nanocrystal has the most stable (111) crystal face exposed and has better sensing performance. The surface of the amorphous layer is covered with an amorphous layer with the thickness of 1-2 nm, and the amorphous layer contains more oxygen vacancies and Ce3+More active catalytic sites can be provided, thereby facilitating amplification of the sensing signal.
On the other hand, the preparation method of the aluminothermic reduction cerium dioxide octahedron material adopts a hydrothermal method to prepare octahedron cerium dioxide nano crystals, and the octahedron cerium dioxide nano crystals are subjected to aluminothermic reduction treatment to obtain the aluminothermic reduction cerium dioxide octahedron material.
The invention combines a hydrothermal method to prepare CeO with different crystal faces exposed2Nano crystal and the prepared CeO is treated by the defect engineering method of aluminothermic reduction reaction2Nanocrystals in which the octahedral electrode material performs best after reduction due to thermite reaction producing large amounts of oxygen defects and Ce on the crystal surface3+The catalytic center with high amount and high activity is provided for catalytic reaction, and the energy of the (111) crystal face is the lowest, so that the formed oxygen vacancy can exist stably, and the optimal electrocatalytic activity is realized.
In a third aspect, use of an aluminothermically reduced ceria octahedral material as described above in the preparation of an electrochemical sensor electrode and/or an electrochemical sensor.
In a fourth aspect, an electrochemical sensor electrode includes any one of the following (a) or (b):
(a) the aluminothermic reduced ceria octahedral material;
(b) a substrate, and the above-described aluminothermally reduced ceria octahedral material supported by the substrate.
In a fifth aspect, a method for preparing an electrode of an electrochemical sensor comprises depositing the above-described aluminothermally reduced ceria octahedral material on a substrate surface by electrophoretic deposition.
In a sixth aspect, an electrochemical sensor comprises at least one working electrode comprising the above-described aluminothermally reduced ceria octahedral material and/or the above-described electrochemical sensor electrode.
In a seventh aspect, an electrode for an electrochemical sensor and/or an electrochemical sensor as described above are provided in H2O2Application in detection.
The invention has the beneficial effects that:
(1) the hydrothermal method of the invention is used for preparing the CeO with octahedral morphology2(CeO2O) exposes the most stable (111) crystal face, facilitating the stable existence of a large number of oxygen vacancies after the subsequent aluminothermic reduction treatment.
(2) The invention leads CeO to be reduced by aluminothermic reduction reaction2Oxygen vacancy and Ce are formed on the surface of the sample3+Octahedral CeO with exposed (111) crystal face2Oxygen vacancy and Ce which nanocrystals can stably form3+Increase the surface catalytic active sites and reduce H2O2In CeO2The adsorption energy of the surface of the nanocrystal is easier to adsorb on a (111) crystal face containing oxygen vacancies, which is favorable for H2O2The sensitivity of the electrochemical sensor is greatly improved. The invention has the advantages of simple equipment, easy control of technological process, low cost, suitability for actual production and high material utilization rate, and the sensor made of the material has excellent electrochemical performance.
(3) The invention preferably uses FTO as a substrate, the FTO has good mechanical stability and high conductivity, and the FTO is used as the substrate to be electrically connectedOctahedron CeO after electrophoretic deposition reduction2The nanocrystalline material can effectively improve the stability and the conductivity of the electrode material.
(4) The invention uses reduced octahedron CeO2H assembled by nanocrystalline electrode material2O2The electrochemical sensor has higher sensitivity, low detection limit and wide linear range, and expands the application range of the semiconductor heterojunction material.
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The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
FIG. 1 shows octahedral CeO before (a) comparative example 1 and after (b) example 12Scanning electron microscope images of nanocrystals;
FIG. 2 shows octahedral CeO before (a, c) comparative example 1 and after (b, d) example 1 reduction according to the invention2Transmission electron microscopy of the nanocrystals (inset is selected area electron diffraction);
FIG. 3 shows pre-reduced CeO of comparative example 1 and comparative example 2 of the present invention2The sample was incubated with (a)0mM and (b)1mM H2O2N of (A)2CV curves in saturated 0.1M PBS; example 1 and comparative example 2 reduced CeO2The sample was incubated with (c)0mM and (d)1mM H2O2N of (A)2Saturating cyclic voltammograms in 0.1M PBS;
FIG. 4 shows octahedral CeO before reduction in comparative example 1 and after reduction in example 1 according to the invention2Nanocrystalline electrodes for H2O2A Chronoamperometric (CA) curve of the electrochemical sensing;
FIG. 5 shows octahedral CeO before reduction in comparative example 1 and after reduction in example 1 according to the invention2Nanocrystalline electrodes for H2O2Calibration curve for electrochemical sensing.
FIG. 6 shows CeO with different morphologies for example 1 and comparative example 2 of the present invention2Scanning electron microscope image of (a): (a) octahedra, (b) cube, (c) rod-like and (d) spherical;
Detailed Description
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
In view of the problems that the prior semiconductor material has low catalytic activity and is difficult to meet the practical sensing application and the like, the invention provides an aluminothermic reduction cerium dioxide octahedron material and a preparation method and application thereof.
The invention provides an aluminothermic reduction cerium dioxide octahedral material, which has an octahedral single crystal structure, exposes a (111) crystal face, contains oxygen vacancies on the surface, and is covered with an amorphous layer with the thickness of 1-2 nm, and the amorphous layer contains oxygen vacancies and Ce3+。
The material provided by the invention is based on octahedral cerium dioxide nanocrystals, and has better sensing performance due to the most stable (111) crystal face exposed in the morphology. The surface of the material is covered with an amorphous layer with the thickness of 1-2 nm, and the material contains more oxygen vacancies and Ce3+More active catalytic sites can be provided, thereby facilitating amplification of the sensing signal.
In some examples of this embodiment, the octahedral single crystal structure has a side length of 100 to 150 nm.
The invention provides a preparation method of an aluminothermic reduction cerium dioxide octahedron material, which comprises the steps of preparing octahedral cerium dioxide nanocrystals by a hydrothermal method, and carrying out aluminothermic reduction treatment on the octahedral cerium dioxide nanocrystals to obtain the aluminothermic reduction cerium dioxide octahedron material.
CeO with different morphologies prepared by hydrothermal method in specific example and comparative example of the invention2In the nanocrystal, octahedral CeO2(CeO2-O) having an edge length of about 100nm to 150nm, CeO being cubic2(CeO2-C) has an edge length of 10nm to 40 nm; rod-shaped CeO2(CeO2-R) a diameter of about 10nm and a length of 50nm to 200 nm; spherical CeO2(CeO2-S) diameter is about 150 nm. The research shows that: the same material has different appearance, crystal phase, grain size and other factors, and may have great influence on the conductivity, catalytic activity and electrochemical performance of the electrode material. The invention carries out aluminothermic reduction reaction and CeO with different shapes2The combination is carried out, and CeO with different crystal faces after reduction is researched2H of nanocrystalline2O2The electrochemical sensing performance solves the problem of low reaction activity of transition metal oxide particles, so that CeO2Surface oxygen vacancies and Ce3+The content is increased, and the catalytic active sites are fully exposed; in addition, the oxygen vacancies formed are also such that H2O2In CeO2The adsorption energy of crystal face is reduced, which is beneficial to H2O2The adsorption and further reaction of the electrochemical sensor greatly improve the sensitivity of the prepared electrochemical sensor. Experiments show that octahedron CeO is reduced by aluminothermic process2The nanocrystals perform best.
In some examples of this embodiment, octahedral cerium dioxide nanocrystals are prepared by hydrothermal methods using cerium nitrate and sodium phosphate.
In the hydrothermal reaction process, different hydrothermal temperatures, times and added reagents have great influence on the crystal morphology. In one or more embodiments, the temperature of the hydrothermal method is 155-165 ℃ and the reaction time is 11.5-12.5 h. Can ensure the formation of octahedral cerium dioxide nano crystal.
The process of aluminothermic reduction treatment comprises the following steps: adding CeO2The nanometer crystal is spread in a burning boat and placed at the downstream of the tube furnace, the excessive aluminum powder is filled in the upstream burning boat, and the reduced CeO with different shapes can be obtained by calcining under the vacuum condition2A nanocrystal.
The existing nanocrystalline materials areAfter the preparation is finished, defect control is difficult to perform. In some embodiments of the embodiment, the aluminothermic reduction is performed under the condition of calcining at 650-750 ℃ for 2-4 h at a heating rate of 4-6 ℃/min under a vacuum condition. The appearance of the sample is not changed after reduction treatment, wherein the octahedron CeO is reduced2Nanocrystal H2O2The enzyme-free electrochemical sensing performance is best. Because a large amount of stable oxygen vacancies and Ce are formed on the surface of the cerium-doped cerium oxide3 +So that the octahedral CeO after reduction2The conductivity, catalytic activity and electrochemical performance of the nanocrystalline electrode material are obviously enhanced.
In a third embodiment of the present invention, there is provided a use of the above-described aluminothermally reduced ceria octahedral material for the preparation of an electrochemical sensor electrode and/or an electrochemical sensor.
In a fourth embodiment of the present invention, there is provided an electrochemical sensor electrode including any one of the following (a) or (b):
(a) the aluminothermic reduced ceria octahedral material;
(b) a substrate, and the above-described aluminothermally reduced ceria octahedral material supported by the substrate.
The substrate comprises a metal substrate, a carbon material substrate and conductive glass, wherein the conductive glass is selected from FTO, ITO, AZO and ZnO: B. ZnO: ga. ZnO: in and Cd2SnO4、Zn2SnO4、TiO2：Nb、SrTiO3：Nb、CuS、CuAlO2And CuAlS2Any of these is preferably FTO.
In a fifth embodiment of the present invention, a method for preparing an electrode of an electrochemical sensor is provided, wherein the above-mentioned aluminothermally reduced ceria octahedral material is deposited on the surface of a substrate by an electrophoretic deposition method.
In a sixth embodiment of the invention, there is provided an electrochemical sensor comprising at least one electrode comprising at least the above-described aluminothermally reduced ceria octahedral material and/or the above-described electrochemical sensor electrode. The electrochemical sensor of the present invention has high sensitivity, low detection limit and wide linear range.
Specifically, the electrochemical sensor comprises one or two or three electrodes, and correspondingly, the electrochemical sensor is a single-electrode, double-electrode or three-electrode electrochemical sensor.
In some embodiments, the electrochemical sensor is a single electrode electrochemical sensor, with only one working electrode.
In some embodiments, the electrochemical sensor is a two-electrode electrochemical sensor comprising a working electrode and a counter electrode.
In some embodiments, the electrochemical sensor is a three-electrode electrochemical sensor comprising a working electrode, a counter electrode, and a reference electrode. More specifically, in the three-electrode electrochemical sensor, the counter electrode is a Pt sheet electrode; the reference electrode is a saturated Ag/AgCl electrode; the electrolyte was a 0.1M PBS solution.
In a seventh embodiment of the present invention, there is provided the above-mentioned thermite-reduced ceria octahedral material, an electrochemical sensor electrode, and/or the above-mentioned electrochemical sensor electrode in H2O2Application in detection.
Application areas include, but are not limited to, the food industry, the chemical industry, the environmental and medical fields; further includes but is not limited to deinking waste paper, fiber bleaching, preparing inorganic epoxide, preparing organic peroxide, sterilizing, treating waste water, treating waste gas, sterilizing for medical purpose, early detecting clinical diseases, monitoring the treating process in real time, detecting the causes of DNA damage and gene mutation, etc.
In order to make the technical solution of the present invention more clearly understood by those skilled in the art, the technical solution of the present invention will be described in detail below with reference to specific examples and comparative examples. If the experimental conditions not specified in the examples are specified, the conditions are generally as usual or as recommended by the reagents company; reagents, consumables and the like used in the following examples are commercially available unless otherwise specified.
Example 1
A,Aluminothermic reduction of octahedral CeO2Preparation of nanocrystalline electrode material
H2O2The enzyme-free electrochemical sensor electrode adopts octahedron CeO after thermite reduction2An electrode material.
The preparation method comprises the following steps:
(1) octahedron CeO2Preparation of nanocrystalline materials
First, 0.08mmol of Na3PO4·12H2O is dissolved in 64mL of deionized water, and after complete dissolution, 8mmol Ce (NO) is added3)3·6H2O, magnetically stirred for 1h, then the mixture was transferred to an 80mL Teflon lined stainless steel autoclave and held in an oven at 160 ℃ for 24 h. After the hydrothermal reaction, the mixture at the bottom of the reaction vessel was centrifuged, and washed with deionized water and ethanol to neutrality. Finally, drying the CeO in an oven at 80 ℃ for 24h, and then raising the temperature to 600 ℃ at the speed of 2 ℃/min to calcine the CeO for 5h to obtain the CeO with the octahedral morphology2And (3) sampling.
(2) Aluminothermic reduction of octahedral CeO2Preparation of nanocrystals
The prepared octahedron CeO2Uniformly spreading the sample in an alumina burning boat, placing the alumina burning boat at one end of the tube furnace far away from the vacuum pump, placing the burning boat containing excessive aluminum powder at one end close to the vacuum pump, and vacuumizing until the pressure is lower than 6 multiplied by 10-4Pa. Then heating to 700 ℃ at the heating rate of 5 ℃/min and keeping for 3h, taking out the sample after cooling to room temperature to obtain the aluminothermic reduced octahedral CeO2A nanocrystalline sample.
(3) Aluminothermic reduction of octahedral CeO2Preparation of nanocrystalline electrodes
And preparing the working electrode by an electrophoretic deposition method. 9.6mg of aluminothermic reduction of octahedral CeO2The nanocrystalline powder and 2.4mg iodine were ultrasonically dispersed in 20mL of acetone. Two pieces of FTO glass were placed in parallel and kept in the above solution under a bias of 10V for 5 min. Obtaining an area of 1cm on FTO2The prepared working electrode is placed in a vacuum oven at 150 ℃ for drying for 2 hours.
Second, assembly H2O2Electrochemical transducerSensor for measuring body weight
Aluminothermic reduction of octahedral CeO in a three-electrode system2The nanocrystalline electrode is used as a working electrode, the saturated Ag/AgCl electrode is used as a reference electrode, and the Pt sheet electrode is used as a counter electrode; preparing 0.1M PBS solution, connecting the three electrodes with a test system, namely completing the assembly H2O2An electrochemical sensor.
FIG. 1 and FIG. 2 show octahedral CeO before and after thermite reduction2The result of the microscopic morphology image of the nano crystal shows that the morphology does not obviously change before and after reduction. As can be seen from FIG. 2, the resulting reduced octahedral CeO2The catalyst has a single crystal structure, exposes a (111) crystal face, and forms an amorphous layer with the thickness of 1nm-2nm on the surface, so that the conductivity can be effectively improved, and more active catalytic sites can be provided. The prepared aluminothermic reduced octahedron CeO2Nanocrystalline material in the presence and absence of 1mM H2O2The results of cyclic voltammogram analysis in 0.1M PBS are shown in FIGS. 3c and 3 d. It can be seen that the octahedron after reduction has the highest current density increase, indicating that it has H2O2The sensing performance is best. FIG. 4 is octahedral CeO before and after reduction2Nanocrystalline electrode material is continuously added with H with different concentrations2O2The measured CA (chronoamperometry) curve is shown by adding trace H2O2The resulting current change was observed in the reduced octahedral CeO of example 12Nanocrystalline electrode material pair H2O2The concentration changes all respond more dramatically. FIG. 5 is octahedral CeO before and after reduction2The nanocrystalline electrode material was calculated from FIG. 4 to obtain the current-H2O2The concentration curve can be fit and calculated to obtain the octahedron CeO before reduction in the invention2H of nanocrystalline2O2The sensitivity of the sensor was 82.23. mu.A/(mM. cm)2) Linear range 20. mu.M-11.61 mM (R)20.995); and reduced octahedral CeO2The sensitivity of the nanocrystalline electrode material is up to 128.83 mu A/(mM cm)2) Linear range 20. mu.M-13.61 mM (R)2＝0.995)。
Comparative example 1: octahedral CeO not reduced by aluminothermic process2Nanocrystalline electrode
As in example 1, except that: the step (2) of aluminothermic reduction treatment is not performed after the step (1).
FIG. 3 shows that octahedral CeO before reduction2The nanocrystalline electrodes exhibited a pair of redox peaks in the potential ranges of-0.25V to-0.35V and-0.4V to-0.5V, respectively (FIG. 3 a). After addition of 1mM H2O2After that, a significant increase in the reduction peak occurred (FIG. 3 b). As can be seen from FIGS. 3c and 3d, the octahedral CeO after reduction2The oxidation reduction peak current of the nanocrystalline electrode is obviously improved, which shows that the octahedral CeO is reduced2The nanocrystal can be used as a signal amplifier to increase H2O2The sensitivity of sensing thereby improves sensing performance.
Comparative example 2: reduced rod-shaped, cube-shaped and spherical CeO2Nanocrystalline electrode
As in example 1, except that: octahedral CeO in step (1)2The preparation method of the nanocrystalline is replaced by rod-shaped, cubic and spherical CeO2A method for preparing a nanocrystal.
Preparation of rod-shaped and cubic CeO2Nano-crystalline: first, 3.2 mmoleCe (NO) was added3)3·6H2O and 0.384mol NaOH are dissolved in 64ml deionized water, the mixture is magnetically stirred for 30min, then the mixture is transferred to a stainless steel high-pressure reaction kettle with an inner lining of 80ml Teflon, the prepared rod-shaped nano-crystals are kept at 100 ℃ for 24h, and the prepared cubic nano-crystals are kept at 180 ℃ for 24 h. After the hydrothermal reaction, the mixture at the bottom of the reaction vessel was centrifuged, and washed with deionized water and ethanol to neutrality. Finally, drying the CeO in an oven at the temperature of 80 ℃ for 24 hours, and then raising the temperature to 600 ℃ at the speed of 2 ℃/min to calcine the CeO for 5 hours to obtain the CeO with the rod-like and cube morphology2And (3) sampling.
Preparation of spherical CeO2Nano-crystalline: firstly 4.6 mmoleCe (NO)3)3·6H2O and 0.8g PVP were dissolved in 56ml ethylene glycol, then 8ml deionized water was added to the mixture, magnetic stirred for 30min, then the mixture was poured into an 80ml Teflon lined stainless steel autoclave and held in an oven at 160 ℃ for 24 h. After hydrothermal reaction, centrifuging the mixture at the bottom of the reaction kettleAnd washing the mixture to be neutral by deionized water and ethanol. Finally, drying the CeO in an oven at the temperature of 80 ℃ for 24 hours, and then raising the temperature to 600 ℃ at the speed of 2 ℃/min to calcine the CeO for 5 hours to obtain the CeO with the spherical morphology2And (3) sampling.
CeO with different morphologies2The morphology of the nanocrystals is shown in fig. 6, and the sensing performance test results are shown in fig. 3. All samples before reduction in the absence of H2O2Under the condition, a pair of oxidation-reduction peaks appear in the potential ranges of-0.25V to-0.35V and-0.4V to-0.5V; add 1mMH2O2After that, the reduction peaks of all samples showed a significant increase and were comparable in level, but rod-like, cubic, spherical CeO2The whole electrochemical activity of the nanocrystalline electrode is obviously lower than that of the reduced octahedral CeO2And (4) a nanocrystalline electrode. The electrochemical feedback of all electrodes after reduction is enhanced compared with that before reduction, but the electrochemical feedback of all electrodes after reduction is enhanced, but the electrodes are rod-shaped, cubic and spherical CeO2Sensing performance of nanocrystalline electrode and reduced octahedral CeO2The nanocrystalline electrode remained poor due to the octahedral CeO after reduction2The (111) crystal face of the nanocrystal can form more stable oxygen vacancies and unsaturated Ce3+Can promote H2O2Adsorption and decomposition.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (3)

1. A preparation method of an aluminothermic reduction cerium dioxide octahedral material is characterized in that cerium nitrate and sodium phosphate are adopted to carry out a hydrothermal method to prepare octahedral cerium dioxide nanocrystals, and the octahedral cerium dioxide nanocrystals are subjected to aluminothermic reduction treatment to obtain the aluminothermic reduction cerium dioxide octahedral material; wherein the temperature of the hydrothermal method is 155-165 ℃, the reaction time is 11.5-12.5 h, and the condition of thermite reduction is calcining for 2-4 h at 650-750 ℃ at the heating rate of 4-6 ℃/min under the vacuum condition.
2. An octahedral material for thermite reduction of cerium oxide, characterized in that it is prepared by the method of claim 1, and has an octahedral single crystal structure with exposed (111) crystal face and oxygen vacancy on the surface, and the octahedral single crystal structure is covered with 1-2 nm amorphous layer containing oxygen vacancy and Ce on the surface3+。
3. The aluminothermally reduced ceria octahedral material according to claim 2, wherein the octahedral single crystal structure has a side length of 100 to 150 nm.
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