Disclosure of Invention
The invention aims to provide a CrP-Re2A preparation method of a P hydrogen evolution and oxygen evolution electrocatalyst solves the problems in the background technology.
In order to achieve the purpose, the invention provides the following technical scheme:
CrP-Re2The preparation method of the P hydrogen evolution and oxygen evolution electrocatalyst comprises the step of obtaining CrP-Re by hydrothermal, simple titration and low-temperature phosphating treatment methods2P composite material, wherein the hydrothermal method comprises the steps of growing chromium on foamed nickel to obtain a chromium-based precursor; and dropping rhenium species on the chromium-based precursor to obtain a chromium-rhenium composite material precursor, and carrying out low-temperature phosphating on the chromium-rhenium composite material precursor.
Further, the preparation of the chromium-based precursor comprises the step of ultrasonically dissolving chromium nitrate nonahydrate and urea in deionized water to obtain a chromium nitrate solution.
Further, the preparation of the chromium-rhenium composite material precursor comprises the step of dissolving the ammonium perrhenate solution in deionized water, absolute ethyl alcohol and Nafion in an ultrasonic mode to obtain the ammonium perrhenate solution.
Further, the concentration of the chromium nitrate solution is 0.03 mol/L, the temperature of the hydrothermal reaction is 120 ℃, and the reaction time is 12 hours.
Further, the concentration of the ammonium perrhenate solution is 0.36 mol/L.
Further, the temperature of the phosphating treatment is 350 ℃ in the atmosphere of nitrogen, and the time is 2 hours.
Compared with the prior art, the invention has the beneficial effects that:
the preparation method is simple, and CrP-Re is obtained by simple hydrothermal, titration and low-temperature phosphating treatment on porous foamed nickel2The P composite material has excellent electro-catalytic hydrogen evolution and oxygen evolution performances under an alkaline condition, and has long service life.
Detailed Description
The technical solution in the embodiment of the present invention will be described below with reference to fig. 1 to 7 in the embodiment of the present invention.
Firstly, preparing commercial Pt/C and RuO2As electrode samples, for comparison with examples of the present invention: weighing 2 mg of commercial Pt/C, dissolving the Pt/C in 200 muL of deionized water, 200 muL of absolute ethyl alcohol and 10 muL of Nafion solution, ultrasonically dissolving for 30 minutes, and then dropping Pt/C slurry subjected to uniform ultrasonic treatment in 1 cm2Dried at room temperature for use.
Preparation of RuO in the same manner as described above2Electrode sample, except commercial Pt/C was changed to RuO2And (4) finishing.
Second, example 1: preparation of CrP/NF material
Step (1), treating foamed nickel: cutting foamed nickel into 3 × 3 cm2Size. Then ultrasonic washing is respectively carried out in 0.5 mol/L sulfuric acid solution, deionized water and ethanol for 10 minutes, and the ultrasonic washing is carried out for three times and naturally aired for standby.
Preparing a chromium nitrate solution: weighing 2.5 mmol of chromium nitrate nonahydrate and 25 mmol of urea, dissolving in 80 mL of deionized water, and performing ultrasonic treatment for 10 minutes to obtain a chromium nitrate solution with the concentration of 0.03 mol/L.
Step (3) hydrothermal reaction: the foamed nickel was placed in a 100 mL reaction vessel and kept at 120 ℃ in an oven for 12 hours. After natural cooling, the foamed nickel is rinsed with a large amount of water and then dried at room temperature for use.
And (4) phosphating: putting the foamed nickel with the chromium precursor in the step (3) into the bottom of a quartz tube, weighing 1 g of sodium hypophosphite and putting the weighed foamed nickel into the opening of the quartz tube, and then heating the quartz tube at the temperature of 5 ℃ for min in a nitrogen atmosphere (20 sccm)-1) And calcining for 2 hours at 350 ℃, naturally cooling to room temperature, taking out, washing with a large amount of deionized water, and airing at room temperature to prepare the CrP/NF material.
Third, example 2: preparation of CrP-Re2P composite material
Step (1), treating foamed nickel: cutting foamed nickel into 3 × 3 cm2Size. Then ultrasonic washing is respectively carried out in 0.5 mol/L sulfuric acid solution, deionized water and ethanol for 10 minutes, and the ultrasonic washing is carried out for three times and naturally aired for standby.
Preparing a chromium nitrate solution: weighing 2.5 mmol of chromium nitrate nonahydrate and 25 mmol of urea, dissolving in 80 mL of deionized water, and performing ultrasonic treatment for 10 minutes to obtain a chromium nitrate solution with the concentration of 0.03 mol/L.
Step (3) hydrothermal reaction: the foamed nickel was placed in a 100 mL reaction vessel and kept at 120 ℃ in an oven for 12 hours. After natural cooling, the foamed nickel is rinsed with a large amount of water and then dried at room temperature for use.
Preparing an ammonium perrhenate solution in the step (4): weighing 0.15 mmol of ammonium perrhenate, adding 200 muL of water, 200 muL of ethanol and 10 muL of Nafion, wherein the concentration of the ammonium perrhenate solution is 0.36 mol/L, and dropping the ammonium perrhenate solution on the foamed nickel (1 cm multiplied by 1 cm) after ultrasonic dissolution.
And (5) dropping rhenium: and (4) dripping the ammonium perrhenate solution prepared in the step (4) on the foamed nickel with the chromium grown in the step (3) by using a liquid transfer gun, and naturally airing for later use.
And (6) phosphating: putting the foamed nickel with the chromium-rhenium precursor in the step (5) into the bottom of a quartz tube, weighing 1 g of sodium hypophosphite and putting the sodium hypophosphite into the opening of the quartz tube, and then heating the quartz tube at the temperature of 5 ℃ for min in a nitrogen atmosphere (20 sccm)-1) Calcining for 2 hours at 350 ℃, naturally cooling to room temperature, taking out, washing with a large amount of deionized water, and airing at room temperature to prepare the CrP-Re2P composite material.
Fourth, example 3: preparation of Re2P/NF material
Step (1), treating foamed nickel: cutting foamed nickel into 3 × 3 cm2Size. Then ultrasonic washing is respectively carried out in 0.5 mol/L sulfuric acid solution, deionized water and ethanol for 10 minutes, and the ultrasonic washing is carried out for three times and naturally aired for standby.
Preparing an ammonium perrhenate solution in the step (2): 0.15 mmol of ammonium perrhenate is weighed, 200 uL of water, 200 uL of ethanol and 10 uL of Nafion are added, and the mixture is dripped on the foamed nickel prepared in the step (1) (1 cm multiplied by 1 cm) after ultrasonic dissolution.
And (3) dropping rhenium: dripping the ammonium perrhenate solution prepared in the step (2) on the foamed nickel (1 multiplied by 1 cm) prepared in the step (1) by using a liquid transfer gun2) And (6) naturally airing for later use.
And (4) phosphating: putting the foamed nickel with the rhenium precursor in the step (3) in the bottom of a quartz tube, weighing 1 g of sodium hypophosphite and putting the weighed foamed nickel in the opening of the quartz tube, and then heating the foamed nickel in a nitrogen atmosphere (20 sccm) (5 ℃ for min)-1) Calcining at 350 deg.C for 2 hr, naturally cooling to room temperature, taking out, washing with deionized water, and air drying at room temperature to obtain Re2P/NF composite material.
Electrochemical test
Electrochemical testing: both hydrogen evolution and oxygen evolution tests were carried out on an electrochemical workstation (Bio-Logic VMP3, France) using a three-electrode system. The CrP-Re prepared in example 2 was used2The P/NF composite material is used as a working electrode, the graphite plate is used as a counter electrode, the saturated calomel electrode is used as a reference electrode, 1.0 mol/L potassium hydroxide solution is used as electrolyte, the test temperature is 25 ℃, the scanning speed is 10 mV/s, and the scanning range is-0.9 to-1.5V. The electrode potential was obtained by applying a saturated calomel electrode, and a Reversible Hydrogen Electrode (RHE) and impedance compensation correction were performed. All potentials herein were obtained according to the following nernst equation:
ERHE = ESCE+0.241+0.059pH-iR
whereiniFor the current tested, R is the solution impedance. The electrolyzed water test was carried out on an electrochemical workstation (Bio-Logic VMP3, France) using a two-electrode system.
Sixth, test results
FIG. 1 shows that the sample of example 2 has CrP and Re, respectively2Characteristic peak of typical X-ray powder diffraction of P.
FIG. 2 (a) is a scanning electron microscope image of example 2 showing a large amount of porous nanoparticles grown on the nickel foam; as shown in FIG. 2 (b) and FIG. 2 (c), transmission electron micrographs are shown; FIG. 2 (d) and FIG. 2 (e) are respectively a particle size distribution and a lattice fringe; FIG. 2 (f) is a high resolution view; the elements are uniformly distributed in the composite as shown in fig. 2 (g).
FIG. 3 shows the results in CrP-Re2The presence of CrP in P/NF composite and electron transfer effect, wherein CrP-Re in FIG. 3 (a)2The combination energy of CrP in the P/NF composite material generates positive offset, Crn+A negative bias is generated, CrP-Re in FIG. 3 (b)2Re in P/NF composite material2The binding energy of P produces a positive shift, Re4+The binding energy of (c) produces a negative bias. Thus, it was confirmed that CrP-Re2The P/NF composite material has electron synergistic effect, so that the conductivity of the catalyst is improved through the electron synergistic effectElectrical properties and intrinsic catalytic activity. FIG. 3 (c) demonstrates that both chromium and rhenium are present as phosphides.
FIG. 4 shows CrP-Re prepared according to the invention2The linear scanning polarization curve of the P/NF composite material under the industrial condition is that when the current density reaches 500 mA/cm2The cell voltage in 30% KOH solution is only 1.89V, when the current density reaches 1000 mA/cm2The cell voltage in 30% KOH solution was only 2.05V, illustrating the CrP-Re of the invention2The P/NF composite material has excellent catalytic performance.
FIG. 5 shows CrP-Re prepared according to the invention2The P/NF composite material is tested in a two-electrode system for 100 hours in 30 percent KOH solution at high current density, the potential has no obvious change, and the CrP-Re composite material shows that2The P/NF composite material has super stability under industrial conditions.
FIG. 6 and FIG. 7 show CrP-Re prepared by the present invention2The P/NF composite material is subjected to linear scanning polarization curve of hydrogen evolution and oxygen evolution in alkaline solution, and when the current density reaches-100 mA/cm2The overpotential for hydrogen evolution only needs 90 mV when the current density reaches 20 mA/cm2The overpotential for oxygen evolution needs only 255 mV to illustrate the CrP-Re of the present invention2The P/NF composite material has excellent electro-catalytic hydrogen evolution and oxygen evolution performances under alkaline conditions.
Comparing examples 1, 2 and 3, in example 1, only hydrothermal reaction is carried out, and the precursor only growing chromium is directly subjected to low-temperature phosphating treatment to obtain CrP/NF, while in example 3, ammonium perrhenate solution is dripped on pure nickel foam, and after natural airing, low-temperature phosphating treatment is carried out to obtain Re2P/NF. As shown in FIG. 6, the current densities of examples 1 and 3 under the alkaline condition reached 100 mA/cm2When the overpotential is 300 mV and 133 mV, the electrocatalytic hydrogen evolution performance is poorer than that of the example 2; as shown in FIG. 7, the current densities of examples 1 and 3 reached 20 mA/cm under the alkaline condition2The overpotentials were 285 mV and 312 mV, which showed inferior electrocatalytic oxygen evolution performance compared to example 2.
In conclusion, the invention simply carries out water on the foamed nickelThermal and simple titration and low-temperature phosphating treatment to obtain CrP-Re2The P composite material has excellent electro-catalytic hydrogen and oxygen evolution performances under an alkaline condition, and has long service life.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention, and it is to be understood that the invention is not limited thereto, but may be modified within the scope of the appended claims.