CN103318978A - Preparation method of mesoporous nickel cobaltate fiber and application thereof - Google Patents

Abstract

The invention brings forward a preparation method of mesoporous nickel cobaltate fiber. According to the preparation method, an organic solvent is added during the preparation process of a precursor; a mixed phase of a water phase and an organic phase is used as a solvent, soluble nickel salt and cobalt salt are used as raw materials, and oxalate is used as a precipitating agent; in a system of Ni<2+>-Co<2+>-NH3-NH4<+>-SG<n->-C2O4<2->-H20-C2H5OH, a fibrous precursor is prepared; and the fibrous precursor is subjected to thermal decomposition in the air atmosphere at 250-400 DEG C so as to obtain the mesoporous NiCo2O4 fiber. According to the invention, coprecipitation based on the Ni-Co ratio set in the raw materials is effectively realized. The prepared NiCo2O4 powder is a cubic phase, has high purity and large specific surface area, is fibrous and porous, and is applicable to be used as a catalyst or an alkaline solution oxygen-evolution/hydrogen-evolution electrode material or direct alcohol fuel cell anode catalyst. The method provided by the invention is simple to operate and easy to control, has advantages of mild condition and low cost, and is suitable for commercialized production.

Description

A kind of preparation method and application of mesoporous nickel cobalt oxide fiber

technical field

The invention belongs to the field of one-dimensional transition metal oxides, and in particular relates to a preparation method and application of nickel cobaltate.

Background technique

In recent years, direct alcohol fuel cells have attracted extensive attention due to their non-toxicity and high theoretical energy density. At present, most of the anode catalysts used are platinum, ruthenium and other noble metals and their binary or multi-component materials, which are costly and prone to CO poisoning in the battery reaction. Therefore, looking for non-noble metals with good catalytic performance and low cost as an alternative anode catalyst has become There is an urgent need for the development of direct alcohol fuel cells. Nickel cobaltate (NiCo ₂ O ₄ ) is a composite oxide with an inverse spinel structure, which has excellent electrochemical properties, and its conductivity and electrochemical activity are higher than those of single metal nickel and cobalt oxides. ³⁺ /Co ²⁺ and Ni ³⁺ /Ni ²⁺ redox couples have been widely used in the fields of catalysis, electrochemical industry and environmental protection. For example: in terms of catalyst application, due to the high activity and good stability of NiCo ₂ O ₄ with spinel structure, it can be used as the active component of catalysts used to control organic waste gas pollution, and can replace expensive platinum, rhodium, palladium and other precious metals ; In terms of electrode materials, NiCo ₂ O ₄ is an ideal anode material for electrolysis of water, which has good catalytic performance for the precipitation and reduction of oxygen; as an electrode material for supercapacitors, nickel cobaltate has a relatively high specific capacitance, It can replace RuO ₂ ; in addition, due to its good electrocatalytic performance, nickel cobaltate can also be used as anode material for sodium ion battery, high rate lithium ion anode material, etc. Although nickel cobalt oxide is so widely used, so far, there are few studies on the application of nickel cobalt oxide in direct alcohol fuel cells. In addition, the performance of the material is directly related to the geometric shape of the material. One-dimensional porous nanomaterials can effectively improve their electrocatalytic performance due to their good contact, short electron and ion transport paths, and high electrical conductivity. Research hotspots.

The main synthesis methods of nickel cobaltate are: high-temperature solid-phase method, mechanochemical synthesis method, sol-gel method, liquid-phase chemical co-precipitation, spray thermal decomposition, hydrothermal method, etc. However, due to its thermally unstable nature, it will partially decompose into a simple oxide and another cobalt-rich spinel phase between 400 and 600 ° C, reducing some activities such as catalytic activity. Therefore, conventional high-temperature solid The phase method is not suitable for nickel cobaltate. A large number of strains and defects are introduced in the mechanochemical synthesis process, and the dispersion of the product is poor; the powder prepared by the spray pyrolysis method has a large particle size, and component segregation is prone to occur; the sol-gel method adds a surfactant, and the particle size of the product Small, evenly distributed ingredients, but high cost, easy to introduce impurities. The hydrothermal method requires higher temperature and pressure, and has higher requirements on reaction conditions and equipment materials, making it difficult to industrialize and expand production. In contrast, the co-precipitation thermal decomposition method has the advantages of controllable powder morphology, accurate stoichiometry, and easy industrial production, and is currently the most studied method. However, due to the different solubility and precipitation kinetics of different metal compounds, the traditional co-precipitation method is prone to segregation, resulting in the co-precipitation process is actually a step-by-step precipitation of each component, that is, the co-precipitation product is a mechanical mixture on the microscopic level, which affects The physical and electrochemical properties of NiCo ₂ O ₄ powders were investigated. Therefore, it is an effective way to realize industrial production of high-performance NiCo ₂ O ₄ powder by developing a method that can effectively realize metal ion co-precipitation, controllable morphology, low cost, and excellent physical and chemical properties of the product. JiangHao et al. (Hao Jiang et al.Hierarchical porous NiCo ₂ O ₄ nanowires for high-rate supercapacitors.Chem.Comm., 2012,48,4465-4467) used oxalic acid as precipitant, Ni(NO ₃ )·6H ₂ O and Co(NO ₃ )·6H ₂ O was used as raw material, P123 was used as soft template, ethanol and PEG were used as solvent, and nickel cobaltate fibers with hierarchical porosity were synthesized by co-precipitation thermal decomposition method, and its performance as a high-rate capacitor was studied. application, this method uses P123 as a soft template, and the process conditions in the production process are difficult to control. In addition, due to the large amount of organic solvent used, the cost is relatively high. Chinese patent (CN201110195864.X, 2011) provides a co-precipitation synthesis method of nickel cobaltate nanoparticles, respectively, the precipitant sodium hydroxide and nickel cobalt metal nitrate Ni(NO ₃ ) 6H ₂ O and Co(NO ₃ ) Dissolve 6H ₂ O in ethylene glycol or dimethylformamide organic solvent, add the metal salt solution to the precipitant solution, and stir for 0.5-48 hours at 0-80°C to obtain the precursor Then the precursor is thermally decomposed at 300-400°C to obtain nano-nickel cobaltate material, which is used to make capacitor electrode materials, and its specific capacitance can reach 671F·g ^-1 . The method is simple to operate and the conditions are mild, but the organic reagent used is ethylene glycol or dimethylamide, and the ratio to deionized water is 1-10:1, and the cost is relatively high. In addition, due to the addition of sodium hydroxide, filtration is relatively Difficult, industrialized operation is difficult. Patent (CN03159576, 2003) invented a method for preparing fibrous nickel-cobalt composite oxide powder, in Ni ²⁺ —Co ²⁺ —NH ₃ —NH ⁴⁺ —SG ^n- —C ₂ O ₄ ^2- —H In the ₂ O reaction system, the fibrous nickel-cobalt composite oxide powder was prepared under the condition of 600℃-900℃ by co-precipitation thermal decomposition method. In the process of precursor synthesis, the pH of this method is controlled in a weakly alkaline environment of 7.0-9.0. It is difficult for nickel-cobalt ions to enter the co-precipitation co-products at the nickel-cobalt ratio set in the raw material. The experimental process needs precise control. Reproducibility is poor, industrial application is difficult, thermal decomposition temperature is high, energy consumption is large, product purity is low, generally a mixture of nickel oxide, cobalt oxide, nickel-cobalt composite oxide, small specific surface area, low catalytic activity. The applicant once disclosed a method for preparing fibrous nickel-cobalt alloy and The preparation method of nickel-cobalt composite oxide powder, in Ni ²⁺ —Co ²⁺ —NH ₃ —NH ⁴⁺ —Cl ^- —C ₂ O ₄ ^2- —H ₂ O—A reaction system, adopts co-precipitation thermal decomposition The fibrous porous nickel-cobalt composite oxide powder was prepared in an oxygen atmosphere. In this method, in an oxygen atmosphere, the precursor needs to be thermally decomposed at a temperature of about 500 ° C to obtain fibrous porous nickel cobaltate. According to the properties of nickel cobaltate itself, this kind of nickel cobaltate product has low purity, small specific surface area, and catalytic activity. Low, high energy consumption.

Contents of the invention

Aiming at the deficiencies of the prior art, the invention proposes a method for preparing mesoporous nickel cobaltate fibers. The preparation method of the mesoporous NiCo ₂ O ₄ fiber is based on soluble nickel salt and cobalt salt as raw materials, oxalate as precipitant, ammonia as pH regulator, ethanol and deionized water as solvent, in Ni ²⁺ - Co ²⁺ -NH ₃ -NH ₄ ⁺ -SG ^n- -C ₂ O ₄ ^2- -H ₂ OC ₂ H ₅ OH (SG ^n- represents the acid radical Cl ^- , SO ₄ ^2- , NO ^3- or CH ₃ COO ^- ) A precursor solution is obtained in the system, and the precursor is washed, dried and thermally decomposed to obtain mesoporous nickel cobaltate fibers.

Another object of the present invention is to propose the mesoporous nickel cobaltate fiber obtained by the preparation method.

The third object of the present invention is to propose the application of the mesoporous nickel cobalt oxide fiber as an electrode material for alcohol fuel cells.

The technical scheme that realizes the above-mentioned purpose of the present invention is:

A preparation method of mesoporous nickel cobaltate fiber, comprising steps:

1) Dissolve soluble nickel salt and soluble cobaltate in deionized water to prepare mixed metal salt solution A containing Ni ²⁺ /Co ²⁺ molar ratio of 1:2;

2) Dissolving stoichiometric oxalate in a mixed solvent of organic reagent and deionized water to configure oxalate solution B;

3) Add the mixed metal salt solution A prepared in step 1) to the oxalate solution B prepared in step 2), while controlling the reaction temperature to 50-75°C, adjust the pH of the solution to 7.5-8.6 with ammonia water, and complete the dropwise addition Continue stirring for 0-2 hours to obtain a precursor solution;

4) filtering the precursor solution obtained in step 3), washing with deionized water and absolute ethanol, and drying the washed precursor;

5) The dried precursor obtained in step 4) is placed at a temperature of 250-400° C., thermally decomposed in an air atmosphere for 0.5-5 hours, and the mesoporous NiCo ₂ O ₄ fibers are obtained after cooling.

In step 3), when solution A is added to oxalate solution B, it needs to be fully dispersed, and it can be stirred while adding dropwise.

In step 4), it can be washed 3-5 times with deionized water, and then washed 2-3 times with absolute ethanol. The drying can be carried out in a vacuum drying oven or a blast drying oven at 70-150° C. for 10-48 hours; other conventional methods in the field can also be used, such as natural drying to remove water and absolute ethanol.

Wherein, the soluble nickel salt is selected from one of nickel chloride hexahydrate, nickel sulfate heptahydrate, nickel nitrate hexahydrate, nickel chloride, nickel sulfate, nickel nitrate; the soluble cobalt salt is selected from cobalt chloride , cobalt sulfate, cobalt nitrate, cobalt chloride hexahydrate, cobalt sulfate heptahydrate, cobalt nitrate hexahydrate.

Wherein, in the mixed metal salt solution A, the total concentration of Ni ²⁺ and Co ²⁺ is 0.3mol/L˜1.2mol/L.

Wherein, the organic reagent is ethanol with a purity greater than 99.0%; in the precursor solution in step 3), the volume ratio of the organic reagent to deionized water is 1:1-20.

Preferably, in the precursor solution, the volume ratio of the organic reagent to the deionized water is 1:1-9.

Wherein, the oxalate is oxalic acid or ammonium oxalate, and the concentration of oxalate is 0.3mol/L˜1.8mol/L.

Wherein, the ratio of the amount of oxalate in the step 3) to the total amount of Ni ²⁺ and Co ²⁺ in the mixed metal salt solution A is 1:1.0˜1.5.

The mesoporous nickel cobaltate fiber prepared by the method of the invention.

Application of the mesoporous nickel cobaltate fiber in the preparation of direct alcohol fuel cell electrode materials. The application is to modify the glassy carbon electrode with the mesoporous nickel cobaltate fiber.

Preferably, the direct alcohol fuel cell is preferably a direct ethanol fuel cell, and the electrode material is an anode electrode material. The specific application method is as follows: the mesoporous nickel cobaltate is dispersed in water, coated on the surface of the glassy carbon electrode, and then coated with Nafion solution, and dried to obtain the anode electrode material. The loading amount of active material on the glassy carbon electrode modified by mesoporous nickel cobaltate is 0.1-1 mg/cm ² .

The beneficial effects of the present invention are:

1. The present invention adopts coprecipitation thermal decomposition method, under normal temperature and pressure, in Ni ²⁺ -Co ²⁺ -NH ₃ -NH ₄ ⁺ -SG ^n- -C ₂ O ₄ ^2- -H ₂ OC ₂ H ₅ In the OH (SG ^n- stands for acid radical Cl ^- , SO ₄ ^2- , NO ₃ ^- or CH ₃ COO ^- ) system, the co-precipitation of the set nickel-cobalt ratio in the raw material is effectively realized, and a fibrous precursor is formed. The mesoporous nickel cobaltate fiber can be obtained in an air atmosphere at -400°C; the whole preparation process is simple to operate, environmentally friendly, with very good experimental reproducibility, low cost, and easy industrial production.

2. The mesoporous NiCo ₂ O ₄ fibers prepared by the method proposed in the present invention have high purity and large specific surface area, and are suitable for electrochemical catalysis. The results of electrochemical tests show that the glassy carbon electrode modified by mesoporous nickel cobalt oxide fibers has good catalytic performance and long-term cycle stability.

3. The obtained mesoporous nickel cobaltate fiber is a spinel-type cubic phase with high purity and high specific surface area. It can be used as an anode catalyst for direct ethanol fuel cells. It can catalyze ethanol with a concentration greater than 5mmol/L, and is also suitable for alkali Electrode materials for oxygen evolution and hydrogen evolution in neutral solutions, electrode materials for supercapacitors.

Description of drawings

Fig. 1 is the SEM image of the mesoporous _NiCo2O4 fiber precursor prepared in _Example 1

Fig. 3 is the SEM figure of the mesoporous nickel cobalt oxide fiber prepared in embodiment 1

Fig. 2 is _the XRD spectrum of the mesoporous nickel cobaltate _NiCo2O4 fiber prepared by embodiment 1;

Fig. 4 is the nitrogen adsorption-desorption isotherm curve of the mesoporous nickel cobaltate fiber.

Fig. 5 is the pore size distribution curve of the prepared mesoporous nickel cobalt oxide fiber.

Figure 6 is the cyclic voltammetry curves of the fibrous nickel cobaltate modified platinum carbon electrode under different ethanol concentrations.

Fig. 7 is the CV diagram of the porous nickel cobaltate modified glassy carbon electrode and the blank glassy carbon electrode in the presence or absence of ethanol solution.

Figure 8 is the cycle life diagram of fibrous nickel cobaltate (the electrolyte solution is 1M NaOH solution)

Detailed ways

The present invention is illustrated with the following preferred embodiments, but they are not used to limit the scope of the present invention.

Example 1:

1) Weigh 0.02 mol of NiCl ₂ 6H ₂ O with a purity of 98.0% and 0.04 mol of CoCl ₂ 6H ₂ O with a purity of 99.0% respectively, and the ratio of NiCl ₂ 6H ₂ O to CoCl ₂ 6H ₂ O is 1:2. Dissolve NiCl ₂ 6H ₂ O and CoCl ₂ 6H ₂ O in 100ml of deionized water to prepare 100ml of mixed metal salt solution A containing Ni ²⁺ and Co ²⁺ . In this mixed metal salt solution A, Ni ²⁺ And the total concentration of Co ²⁺ is 0.6mol/L.

2) Dissolve 0.072mol of oxalic acid with a purity of 99% in a mixed solvent of 50ml of organic reagent ethanol and 50ml of deionized water. The organic reagent is ethanol with a purity of 99.7%, and configure it as oxalic acid solution B.

3) Add 100ml of mixed metal salt solution A prepared in step 1 dropwise to 100ml of oxalic acid solution B prepared in step 2, stir while adding dropwise, while controlling the reaction temperature to 60°C, adjust the pH value with ammonia water, and keep the pH value 8.2, continue to stir for 0.5 hours after the dropwise addition to obtain the precursor solution;

4) Filter the precursor solution obtained in step 3), wash it four times with deionized water, and wash it twice with absolute ethanol to prepare the precursor, and put the precursor in a vacuum drying oven at a temperature of 100°C Dry for 24 hours; the SEM photo of the precursor after drying is shown in Figure 1.

5) The dried precursor obtained in step 4) was placed in an electric furnace regulated by PID, the temperature was controlled at 300°C, thermally decomposed in an air atmosphere for 1 hour, and cooled to obtain mesoporous NiCo ₂ O ₄ fibers. Its SEM photo is shown in Figure 2.

6) Characterize the mesoporous nickel cobalt oxide fiber obtained in step 5), the X-ray diffraction data and the position of the diffraction peak corresponding to the XRD pattern (Figure 3) are consistent with the standard card of spinel phase NiCo ₂ O ₄ (JCPDS No. .20-0781) consistent, no other impurity phases appear, indicating that the synthesis is nickel cobaltate with high purity. From the results of the nitrogen adsorption-desorption isotherm curve in Figure 4, it can be seen that the synthesized mesoporous nickel cobaltate fiber has a relatively high specific surface area (54.5m ² g ^-1 ), and the pore size distribution curve in Figure 5 shows that the pores of the nickel cobaltate product are It is mesoporous (the average pore diameter is 13.4nm), and the specific surface area of desorption pores is relatively large (76.8m ² g ^-1 ).

Example 2: Electrode material prepared by mesoporous nickel cobaltate and its electrochemical characterization

A modified glassy carbon electrode was used as the working electrode. First, use 50nm alumina polishing powder to grind the glassy carbon electrode on a polishing cloth until the surface is smooth; then ultrasonically wash it three times in distilled water, and dry it for use. Take 0.05 g of the mesoporous nickel cobaltate powder prepared in Step Example 1, dissolve it in 2 mL of distilled water, and disperse evenly by ultrasonic; use a micro-sampler to draw 0.4 μL of sample, and apply it on the surface of the glassy carbon electrode. After drying at room temperature, 0.2 μL of Nafion solution (0.5 wt%) was applied to the surface of the sample. After drying at normal temperature, a glassy carbon electrode modified with mesoporous nickel cobaltate is obtained, with a loading capacity of 0.5 mg/cm ² .

The glassy carbon electrode modified by mesoporous nickel cobaltate was placed in a solution containing ethanol and NaOH, a platinum sheet (1cm×1cm) was used as the counter electrode, and a 232-type saturated calomel electrode (SCE) was used as the reference electrode. The platinum carbon electrode was used for electrochemical tests (Figure 6, cyclic voltammetry curve, scan speed 50mV/s). In FIG. 6 , the ethanol concentrations indicated by the serial numbers are 1:0.5M, 2:0.2M, 3:0.1M, 4:0.05M, 5:0.02M, 6:0.005M, and 7:0M. When catalyzing ethanol, the minimum concentration of ethanol is only 0.005mol/L, reflecting good electrocatalytic performance.

The glassy carbon electrode without mesoporous nickel cobaltate modification was used as the working electrode, and the electrochemical test (cyclic voltammetry) was also done. The comparison with the results of the glassy carbon electrode modified by mesoporous nickel cobaltate is shown in Figure 7. The serial numbers in Figure 7 represent 1: the CV curve of the nickel cobaltate modified glassy carbon electrode in ethanol solution (the concentration of ethanol is 0.5M, and the electrolyte solution is 1M NaOH solution), 2: the nickel cobaltate modified glassy carbon electrode in the ethanol-free solution 3: CV curve of blank glassy carbon electrode in ethanol solution, 4: CV curve of blank glassy carbon electrode in ethanol-free solution. It can be seen from Figure 7 that mesoporous nickel cobaltate has good catalytic performance.

Figure 8. The glassy carbon electrode modified by mesoporous nickel cobaltate was subjected to 500 cycles in 0.5M ethanol solution (the electrolyte solution was 1M NaOH solution), and the curves of the first cycle (1-1st cycle) and the 500th cycle (2-500th cycle ), the results show that after 500 redox cycles, the peak current only drops by 25%, which has good cycle stability.

Example 3:

1) Weigh 0.02 mol of NiCl ₂ 6H ₂ O with a purity of 98.0% and 0.04 mol of CoCl ₂ 6H ₂ O with a purity of 99.0% respectively, the amount of NiCl ₂ 6H ₂ O and CoCl ₂ 6H ₂ O The ratio is 1:2. Dissolve the NiCl ₂ 6H ₂ O and CoCl ₂ 6H ₂ O in 100ml of deionized water together to prepare mixed metal salt solution A100ml containing Ni ²⁺ and Co ²⁺ , the mixed metal salt solution In A, the total concentration of Ni ²⁺ and Co ²⁺ is 0.6mol/L.

2) Dissolve 0.072mol of ammonium oxalate with a purity of 99.0% in a mixed solvent of 20ml of ethanol and 80ml of deionized water, the ethanol is ethanol with a purity of 99.7%, and configure as oxalate solution B.

3) Add 100ml of mixed metal salt solution A prepared in step 1 dropwise to 100ml of oxalic acid solution B prepared in step 2), stir while adding dropwise, while controlling the reaction temperature to 60°C, adjust the pH value with ammonia water, and maintain the pH value is 8.0, after the dropwise addition, continue to stir for 0.5 hours to obtain a precursor solution;

4) Filter the precursor solution obtained in step 3), wash 5 times with deionized water, and wash 2 times with absolute ethanol to prepare the precursor, and dry the precursor in a vacuum drying oven for 24 hours ;

5) The dried precursor prepared in step 4) was placed in a PID-regulated electric furnace at a controlled temperature of 280°C, and thermally decomposed in an air atmosphere for 2 hours to obtain mesoporous NiCo ₂ O ₄ fibers.

Characterize the mesoporous nickel cobaltate fiber obtained in step 5), and the XRD pattern shows that the synthesized one is nickel cobaltate with high purity and no impurities. According to the nitrogen adsorption-desorption isotherm curve test, the synthesized mesoporous nickel cobaltate fiber has a specific surface area of 53.9m ² g ^-1 .

Example 4:

1) Weigh 0.02 mol of NiCl ₂ 6H ₂ O with a purity of 98.0% and 0.04 mol of CoCl ₂ 6H ₂ O with a purity of 99.0% respectively, and the ratio of NiCl ₂ 6H ₂ O to CoCl ₂ 6H ₂ O is 1:2. Dissolve NiCl ₂ 6H ₂ O and CoCl ₂ 6H ₂ O in 100ml of deionized water to prepare 100ml of mixed metal salt solution A containing Ni ²⁺ and Co ²⁺ . In this mixed metal salt solution A, Ni ²⁺ And the total concentration of Co ²⁺ is 0.6mol/L.

2) Dissolve 0.072mol of oxalic acid with a purity of 99.0% in a mixed solvent of 90ml of organic reagent ethanol (purity of 99.7%) and 10ml of deionized water to prepare oxalic acid solution B.

3) Add 100ml of mixed metal salt solution A prepared in step 1 dropwise to 100ml of oxalic acid solution B prepared in step 2, stir while adding dropwise, while controlling the reaction temperature to 60°C, adjust the pH value with ammonia water, and keep the pH value 8.6, continue to stir for 0.5 hours after the dropwise addition to obtain the precursor solution;

4) Filter the precursor solution obtained in step 3), wash 4 times with deionized water, and wash 3 times with absolute ethanol to prepare the precursor, and dry the precursor in a vacuum drying oven for 24 hours;

5) The dried precursor prepared in step 4) was placed in a PID-regulated electric furnace at a controlled temperature of 400 °C, and thermally decomposed in an air atmosphere for 1 hour to obtain mesoporous NiCo ₂ O ₄ fibers.

Characterize the mesoporous nickel cobaltate fiber obtained in step 5), and the XRD pattern shows that the synthesized one is nickel cobaltate with high purity and no impurities. According to the nitrogen adsorption-desorption isotherm curve test, the synthesized mesoporous nickel cobaltate fiber has a specific surface area of 55.2m ² g ^-1 .

Example 5:

1) Weigh 0.01 mol of Ni(NO ₃ ) ₂ 6H ₂ O with a purity of 98.0% and 0.02 mol of Co(NO ₃ ) ₂ 6H ₂ O with a purity of 99.0% and Ni(NO ₃ ) ₂ 6H ₂ O The ratio of the amount of substance to Co(NO ₃ ) ₂ ·6H ₂ O is 1:2. Dissolve Ni(NO ₃ ) ₂ 6H ₂ O and Co(NO ₃ ) ₂ 6H ₂ O in 100ml of deionized water to prepare mixed metal salt solution A100ml containing Ni ²⁺ and Co ²⁺ . In mixed metal salt solution A, the total concentration of Ni ²⁺ and Co ²⁺ is 0.3mol/L.

2) Dissolve 0.045 mol of ammonium oxalate with a purity of 99.0% in a mixed solvent of 50 ml of organic reagent ethanol and 50 ml of deionized water. The organic reagent is ethanol with a purity of 99.7%, and configure it as oxalic acid solution B.

3) Add 100ml of mixed metal salt solution A prepared in step 1 dropwise to 100ml of oxalic acid solution B prepared in step 2, and stir while adding dropwise, while controlling the reaction temperature to 60°C, using ammonia water to condition the pH value and keep the pH value 8.2, continue to stir for 0.5 hours after the dropwise addition to obtain the precursor solution;

4) Filter the precursor solution obtained in step 3), wash four times with deionized water, and wash twice with absolute ethanol to obtain a precursor, and dry the precursor in a vacuum drying oven for 24 hours;

5) The dried precursor obtained in step 4) was placed in an electric furnace regulated by PID, the temperature was controlled at 280°C, and thermal decomposition was carried out in an air atmosphere for 1 hour to obtain mesoporous NiCo ₂ O ₄ fibers.

Characterize the mesoporous nickel cobaltate fiber obtained in step 5), and the XRD pattern shows that the synthesized one is nickel cobaltate with high purity and no impurities. According to the nitrogen adsorption-desorption isotherm curve test, the synthesized mesoporous nickel cobaltate fiber has a specific surface area of 55.8m ² g ^-1 .

Embodiment 6:

1) Weigh 0.04 mol of NiSO ₄ 7H ₂ O with a purity of 98.0% and 0.08 mol of CoSO ₄ 7H ₂ O with a purity of 99.0% respectively. The ratio of NiSO ₄ 7H ₂ O to CoSO ₄ 7H ₂ O is 1:2. Dissolve NiSO ₄ 7H ₂ O and CoSO ₄ 7H ₂ O in 100ml of deionized water to prepare 100ml of mixed metal salt solution A containing Ni ²⁺ and Co ²⁺ . In said mixed metal salt solution A, Ni The total concentration of ²⁺ and Co ²⁺ is 1.2mol/L.

2) Dissolve 0.18 mol of ammonium oxalate with a purity of 99.0% in a mixed solvent of 50 ml of organic reagent ethanol and 10 ml of deionized water. The organic reagent is ethanol with a purity of 99.7%, and configure it as oxalate solution B.

3) Add 100ml of mixed metal salt solution A prepared in step 1 dropwise to 100ml of oxalate solution B prepared in step 2), stir while adding dropwise, and control the reaction temperature at 65°C, adjust the pH value with ammonia water, and keep The pH value is 8.2, and the stirring is continued for 0.5 hours after the dropwise addition to obtain the precursor solution;

4) Filter the precursor solution obtained in step 3), wash four times with deionized water, and wash twice with absolute ethanol to obtain a precursor, and dry the precursor in a vacuum drying oven for 24 hours;

5) The dried precursor obtained in step 4) was placed in an electric furnace regulated by PID, the temperature was controlled at 350°C, and thermal decomposition was carried out in an air atmosphere for 1 hour to obtain mesoporous NiCo ₂ O ₄ fibers.

Characterize the mesoporous nickel cobaltate fiber obtained in step 5), and the XRD pattern shows that the synthesized one is nickel cobaltate with high purity and no impurities. According to the nitrogen adsorption-desorption isotherm curve test, the synthesized mesoporous nickel cobaltate fiber has a specific surface area of 54.9m ² g ^-1 .

Embodiment 7:

1) Weigh 0.04 mol of NiCl ₂ 6H ₂ O with a purity of 98.0% and 0.08 mol of CoCl ₂ 6H ₂ O with a purity of 99.0% respectively, the amount of NiCl ₂ 6H ₂ O and CoCl ₂ 6H ₂ O The ratio is 1:2. Dissolve the NiCl ₂ 6H ₂ O and CoCl ₂ 6H ₂ O in 100ml of deionized water together to prepare mixed metal salt solution A100ml containing Ni ²⁺ and Co ²⁺ , the mixed metal salt solution In A, the total concentration of Ni ²⁺ and Co ²⁺ is 1.2mol/L.

2) Dissolve 0.18 mol of ammonium oxalate with a purity of 99.0% in a mixed solvent of 50 ml of organic reagent ethanol and 50 ml of deionized water. The organic reagent is ethanol with a purity of 99.7%, configured as oxalate solution B.

3) Add 100ml of mixed metal salt solution A prepared in step 1 dropwise to 100ml of oxalate solution B prepared in step 2, stir while adding dropwise, and control the reaction temperature at 65°C at the same time, condition the pH value with ammonia water, and maintain the pH The value is 8.2, after the dropwise addition, continue to stir for 0.5 hours to obtain the precursor solution;

4) Filter the precursor solution obtained in step 3), wash four times with deionized water, and wash twice with absolute ethanol to obtain a precursor, and dry the precursor in a vacuum drying oven for 24 hours;

5) The dried precursor prepared in step 4) was placed in a PID-regulated electric furnace at a controlled temperature of 350°C, and thermally decomposed in an air atmosphere for 1 hour to obtain mesoporous NiCo ₂ O ₄ fibers.

Characterize the mesoporous nickel cobaltate fiber obtained in step 5), and the XRD pattern shows that the synthesized one is nickel cobaltate with high purity and no impurities. According to the nitrogen adsorption-desorption isotherm curve test, the synthesized mesoporous nickel cobaltate fiber has a specific surface area of 55.8g ^-1 .

Other physical and chemical properties of the products of Examples 1 and 2-7 are as follows: short diameter ≤ 250nm, fiber long diameter ≥ 10μm, carbon ≤ 0.01wt%, sulfur ≤ 0.001wt%, iron ≤ 0.01wt%.

The above embodiments are only descriptions of preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. On the premise of not departing from the design spirit of the present invention, ordinary engineers and technicians in the field may make various modifications to the technical solutions of the present invention. and improvements, all should fall within the scope of protection determined by the claims of the present invention.

Claims (10)

1. the preparation method of a mesoporous cobalt acid nickel fiber is characterized in that, comprises step:

1) soluble nickel salt and solubility cobaltates are dissolved in the deionized water, are configured to contain Ni ²⁺/ Co ²⁺Mol ratio is the mixed salt solution A of 1:2;

2) will be dissolved in the mixed solvent of organic reagent and deionized water by stoichiometric oxalate, be configured to oxalate solution B;

3) the mixed salt solution A with step 1) configuration joins step 2) among the oxalate solution B of configuration, controlling simultaneously temperature of reaction is 50～75 ℃, regulating the pH value with ammoniacal liquor is 7.5～8.6, dropwises to continue to stir 0～2 hour, obtains precursor solution;

4) with step 3) precursor solution that obtains filters, and is with deionized water and absolute ethanol washing, that the presoma after the washing is dry;

5) with step 4) the dried presoma that makes places under 250～400 ℃ of temperature, carries out thermolysis 0.5～5 hour under air atmosphere.

2. preparation method according to claim 1 is characterized in that, described soluble nickel salt is selected from a kind of in six water nickelous chlorides, seven water single nickel salts, six water nickelous nitrates, nickelous chloride, single nickel salt, the nickelous nitrate; Described solubility cobalt salt is selected from a kind of in cobalt chloride, rose vitriol, Jing Ti/Bao Pian COBALT NITRATE CRYSTALS/FLAKES, CoCL2 6H2O, heptahydrate, the cobalt nitrate hexahydrate.

3. preparation method according to claim 1 is characterized in that, among the described mixed salt solution A, and Ni ²⁺And Co ²⁺Total concn be 0.3mol/L～1.2mol/L.

4. preparation method according to claim 1 is characterized in that, described organic reagent is purity greater than 99.0% ethanol.

5. arbitrary described preparation method is characterized in that according to claim 1～4, described step 3) in precursor solution in, the volume ratio of organic reagent and deionized water is 1:1～20; Preferably, in the described precursor solution, the volume ratio of organic reagent and deionized water is 1:1～9.

6. preparation method according to claim 1 is characterized in that, among the described oxalate solution B, described oxalate is oxalic acid or ammonium oxalate, and the concentration of oxalate is 0.3mol/L～1.8mol/L.

7. preparation method according to claim 1 is characterized in that, the Ni among described step 3) Oxalate and the described mixed salt solution A ²⁺And Co ²⁺The ratio of total amount of substance be 1:1.0～1.5.

8. the mesoporous cobalt acid nickel fiber for preparing of the arbitrary described method of claim 1～7.

9. mesoporous cobalt acid nickel fiber claimed in claim 8 can be used as the direct alcohol fuel cell electrode materials.

10. application according to claim 9 is characterized in that, is to use the fiber-modified glass-carbon electrode of mesoporous cobalt acid nickel.

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