CN115522224B - Novel catalyst material, preparation method and application thereof - Google Patents
Novel catalyst material, preparation method and application thereof Download PDFInfo
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- 239000000463 material Substances 0.000 title claims abstract description 36
- 238000002360 preparation method Methods 0.000 title abstract description 7
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- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 36
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- 238000000034 method Methods 0.000 claims description 9
- 238000001354 calcination Methods 0.000 claims description 7
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 6
- 238000010041 electrostatic spinning Methods 0.000 claims description 5
- 229910002422 La(NO3)3·6H2O Inorganic materials 0.000 claims description 4
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- 238000010408 sweeping Methods 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 229920000557 Nafion® Polymers 0.000 description 1
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- ZOMNIUBKTOKEHS-UHFFFAOYSA-L dimercury dichloride Chemical compound Cl[Hg][Hg]Cl ZOMNIUBKTOKEHS-UHFFFAOYSA-L 0.000 description 1
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
- C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
- C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
- C25B11/091—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B1/00—Electrolytic production of inorganic compounds or non-metals
- C25B1/01—Products
- C25B1/02—Hydrogen or oxygen
- C25B1/04—Hydrogen or oxygen by electrolysis of water
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
Abstract
The invention belongs to the technical field of electrochemistry, and particularly relates to a novel catalyst material, a preparation method and application thereof. The novel catalyst material is a hollow nano tubular structure with heterojunction characteristics formed by compounding La 2IrO6 and IrO 2, wherein the hollow nano tubular structure has high-valence iridium atoms which exist stably. The novel catalyst material provided by the invention not only has excellent catalytic activity of acid OER in acid oxygen precipitation, but also has excellent catalytic stability, and is an oxygen evolution reaction catalyst with great potential.
Description
Technical Field
The invention belongs to the technical field of electrochemistry, and particularly relates to a novel catalyst material, a preparation method and application thereof.
Background
Electrolytic water to produce hydrogen is considered a promising energy conversion technology. Compared with the hydrogen evolution reaction of two electrons, the Oxygen Evolution Reaction (OER) of the anode is a multi-proton/electron coupling and slow dynamics process, which restricts the industrial development of the electrolyzed water. Therefore, development of an OER catalyst with high efficiency and stability is urgent. The electrolytic water can be carried out under both acidic and alkaline conditions, and the catalytic materials for the anodic oxygen evolution reaction in alkaline medium are studied very much, but the ionic conductivity of alkaline electrolyte is significantly lower than that of hydronium ions, and is easy to react with carbon dioxide to accumulate carbonate pollutants. Proton Exchange Membrane (PEM) cells offer significant advantages over alkaline cells, with higher ionic conductivity, fewer side reactions, greater current density, and higher purity hydrogen. Therefore, the study of anodic reactions under acidic conditions is of great practical importance for promoting electrochemical decomposition of water.
Currently, most catalysts applied to basic OER have proven to be unable to operate stably for long periods of time in the PEM. This is mainly because the PEM operating environment is strongly acidic, placing higher demands on the corrosion resistance of the catalyst, even though a few catalysts have good stability in acid, with surface reconstruction often accompanying in the electrocatalytic process. Therefore, revealing the structure-activity relationship of the catalyst becomes very difficult, which is disadvantageous for the development and application of the catalyst. At present iridium-based oxide (IrO 2) remains the most desirable catalyst in the PEM and is even considered the only electrocatalyst in the acidic OER that is likely to have reasonable catalytic activity and stability. However, iridium metal is a noble metal, and has a rare earth reserve and high price, which limits its large-scale application. Therefore, it is imperative to develop an acidic OER catalyst having a low content of noble metal Ir while having high activity and stability.
Composite oxides are considered as an effective way to reduce the amount of noble metal used and to increase the intrinsic activity of the metal. Perovskite (composite oxide containing a small amount of rare noble metal) enriches the types and the number of OER catalysts due to its flexible and tunable structure, and its clear specific crystal structure can be generally used as a model catalyst to analyze the reaction mechanism, which is widely appreciated by researchers. For example, by Pulsed Laser Deposition (PLD) with SrTiO 3 as the substrate, a 3C-SrIrO 3 film is deposited that exhibits good catalytic activity and stability under acidic conditions and reduces the iridium content of the bulk catalyst. Studies have shown that iridium species in the high oxidation state (such as Ir 5+ or Ir 6+) have demonstrated better OER catalytic performance. However, how to synthesize and stabilize the high Ir catalyst remains a challenge.
Disclosure of Invention
The invention aims to overcome the defects and shortcomings in the prior art and provides a novel catalyst material, a preparation method and application thereof.
In a first aspect of the invention, a novel catalyst material is provided, and is a hollow nano tubular structure with heterojunction characteristics formed by compounding La 2IrO6 and IrO 2, and is a La 2IrO6/IrO2 heterojunction structure containing high-valence iridium.
IrO 2 in the La 2IrO6/IrO2 heterojunction structure can stabilize iridium atoms of high-valence La 2IrO6, wherein two Irs can mutually adjust, so that the Ir has a faster electron transfer rate, and has proper OH adsorption capacity and a faster deprotonation rate.
Comparing the Ir 4f spectrum of La 2IrO6/IrO2 with the Ir 4f spectrum of commercial IrO 2, it was found that Ir 4f in La 2IrO6/IrO2 had higher binding energy overall, and the higher valence state of Ir, indicating that La 2IrO6/IrO2 had an iridium atom higher than +4, also demonstrated successful synthesis of the stably present iridium in the higher valence state. Polarization curve (LSV) tests were performed on different catalysts, such as commercial IrO 2 catalyst (IrO 2 -C), electrospun prepared IrO 2 nanowires (IrO 2 -ES), and La 2IrO6/IrO2 provided by the present invention, and an overpotential at a current density of 10 mAcm -2 was typically used to evaluate the catalyst for catalytic activity. A smaller overpotential represents a better catalytic activity of the catalyst. La 2IrO6/IrO2 showed the best catalytic performance with the least overpotential among several catalysts, only 279 mV. Meanwhile, the overpotential of La 2IrO6/IrO2 is smaller than that of commercial IrO 2, which shows that La 2IrO6/IrO2 has good commercial application potential. The Tariff slope curve can be obtained by fitting the polarization curve, and the Tariff slope of La 2IrO6/IrO2 is the smallest, which indicates that La 2IrO6/IrO2 has faster OER reaction kinetics and is beneficial to the OER reaction. To investigate the intrinsic catalytic activity of the La 2IrO6/IrO2 catalyst, the mass activity of La 2IrO6/IrO2 was calculated by LSV curve, and the mass activity of La 2IrO6/IrO2 was far better than that of the commercial IrO 2 catalyst, and at an overpotential of 300 mV, the mass activity of La 2IrO6/IrO2 was about 5 times as high as that of the commercial IrO 2 catalyst, further proving that La 2IrO6/IrO2 is a potential acidic OER catalyst.
Furthermore, the La 2IrO6/IrO2 catalyst material provided by the invention also shows excellent catalytic stability. La 2IrO6/IrO2 was tested for stability by chronopotentiometry, la 2IrO6/IrO2 was continuously and stably operated at a current density of 10 mAcm -2 over 80 h, little decay in catalytic performance occurred, and IrO 2 was drastically reduced in performance under this condition for only a few hours.
Electrochemical impedance spectroscopy is also commonly used to explore the reaction mechanism of the catalyst. The catalyst was EIS tested at OER potential (1.3V vs. Ag/AgCl), la 2IrO6/IrO2 had a lower phase angle and shifted to high frequency than IrO2-ES, indicating that La 2IrO6/IrO2 had a stronger adsorption capacity for OER intermediate OH and a faster deprotonation rate in OER reactions.
In conclusion, the La 2IrO6/IrO2 heterojunction structure containing high-valence iridium provided by the invention has excellent electrochemical activity and stability in the electrolytic water oxygen evolution reaction under the acidic condition, and is a catalyst for oxygen evolution reaction with great potential.
In a second aspect of the present invention, there is provided a process for the preparation of a novel catalyst material as described above, comprising the steps of:
(1) Dissolving La (NO 3)3·6H2 O and K 2IrCl6 in a mixed solution of ethanol and N, N-dimethylformamide to obtain a precursor solution;
(2) Adding a spinning aid into the precursor solution to obtain a spinning solution;
(3) Spinning the spinning solution through an electrostatic spinning device to obtain a La 2IrO6/IrO2/LaOCl precursor;
(4) Calcining the La 2IrO6/IrO2/LaOCl precursor in air to obtain La 2IrO6/IrO2/LaOCl nanotube;
(5) And purifying the La 2IrO6/IrO2/LaOCl nanotube obtained by calcination by using hydrochloric acid to obtain the La 2IrO6/IrO2 nanotube, namely the novel catalyst material.
The La 2IrO6/IrO2/LaOCl precursor is synthesized by adopting an electrostatic spinning method, and LaOCl impurities are removed by hydrochloric acid purification treatment, so that a pure La 2IrO6/IrO2 catalyst is obtained. XRD analysis is carried out on the sample after the purification is completed, so that the IrO 2 phase exists in the purified sample, and the residual diffraction peak is consistent with the La 2IrO6 diffraction peak reported in the literature, which proves that the La 2IrO6/IrO2 catalyst material is successfully synthesized, the operation is simple and safe, the large-scale synthesis is easy, and the cost is saved.
Preferably, in step (1), the molar ratio of La (NO 3)3·6H2 O to K 2IrCl6) is 1:1.
Preferably, in step (2), the spinning aid is polyvinylpyrrolidone.
Preferably, in step (4), the calcination temperature is 750 ℃.
Preferably, in step (5), the hydrochloric acid treatment time is at least 16 hours.
In a third aspect of the invention there is provided the use of a novel catalyst material as described above as an anode reaction catalyst. The La 2IrO6/IrO2 catalyst has high activity and high stability in acid oxygen precipitation, and has good application prospect.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are required in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the invention, and that it is within the scope of the invention to one skilled in the art to obtain other drawings from these drawings without inventive faculty.
Fig. 1: a La 2IrO6/IrO2 nanotube synthesis schematic;
Fig. 2: XRD diffraction pattern of La 2IrO6/IrO2/LaOCl;
Fig. 3: (a-b) low-power and high-power SEM images of La 2IrO6/IrO2/LaOCl, (c-f) TEM and HRTEM images of bulk impurities on La 2IrO6/IrO2/LaOCl, (g-h) TEM and HRTEM images of particles on La 2IrO6/IrO2/LaOCl pipe walls, (i) elemental distribution images of La 2IrO6/IrO2/LaOCl;
Fig. 4: XRD diffractograms of samples at different hydrochloric acid treatment times;
Fig. 5: XRD pattern of La 2IrO6/IrO2;
Fig. 6: (a) SEM images of La 2IrO6/IrO2, (b) TEM images of La 2IrO6/IrO2, (c) HRTEM images of La 2IrO6/IrO2, (d) elemental distribution images of La 2IrO6/IrO2;
Fig. 7: la 2IrO6/IrO2/LaOCl、La2IrO6/IrO2 and Cl 2p and Ir 4f XPS spectra of commercial IrO 2;
Fig. 8: (a) LSV curves of different materials in 0.5M H 2SO4 solution environment, all the curves are compensated by 90% iR, and the sweeping speed is 10 mVs -1; (b) a catalyst tafel slope plot corresponding to the LSV curve;
Fig. 9: (a) Mass activity LSV curves of different materials in 0.5M H 2SO4 solution environment, all the curves being compensated by 90% iR, catalyst overpotential at 10 mVs -1;（b）10 mAcm-2 current density at sweep speed and catalyst mass activity histogram at 300 mV overpotential;
fig. 10: determining La 2IrO6/IrO2 stability by a chronopotentiometric method, and observing voltage change with time under the condition that the catalyst is kept at 10 mAcm -2 current density;
Fig. 11: (a-b) cyclic voltammograms of La 2IrO6/IrO2 and IrO 2 -ES over a range of non-faradaic capacitive currents at scan rates of 10, 20, 30, 40 and 50 mV s -1, (c) fitting a plot of current density differences versus scan rate. The linear slope corresponds to twice the double layer capacitance Cdl, representing ECSA;
Fig. 12: multi-step current test, the initial current density is 10 mAcm -2, the end current density is 35 mAcm -2, and the current density is uniformly increased at intervals of 5 mAcm -2;
Fig. 13: (a) La 2IrO6/IrO2 and IrO 2 -ES Nyquist diagram, (b) La 2IrO6/IrO2 and IrO 2 -ES phase diagram at 1.3V.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings, for the purpose of making the objects, technical solutions and advantages of the present invention more apparent.
Example 1: preparation of La 2IrO6/IrO2 catalyst Material
La 2IrO6/IrO2 hollow nano-tubes are prepared by an electrostatic spinning method, and the method specifically comprises the following steps: 216.5 mg La (NO 3)3·6H2 O and 241.5 mg K 2IrCl6 (molar ratio 1:1) were dissolved in a mixed solution of 2 mL ethanol and 8mL N, N-dimethylformamide, 15 wt% PVP was added to the precursor solution after the completion of the dissolution to increase the solution viscosity, the final spinning solution was transferred to a syringe and clamped in a syringe pump, the voltage applied to the tip was 20 kV, the distance from the tip (syringe injection rate was 0.6 m h -1) to the collector was 15 cm, the temperature of the whole system was maintained at 40 ℃, the film collected on a silicone paper was calcined in air at 750℃to obtain La 2IrO6/IrO2/LaOCl nanotubes, and the temperature elevation rate was 0.5℃min -1. The nanotubes obtained by the calcination were purified by hydrochloric acid to obtain La 2IrO6/IrO2 nanotubes.
Example 2: characterization of La 2IrO6/IrO2 catalyst materials
The X-ray diffraction pattern was obtained by using a D/MAX 2400 diffractometer, cu ka radiation (40 kV, 100 mA, λ= 1.54056 a); scanning electron microscope images were obtained by using JSM-6700 (spot 3.0, 15 kV); transmission electron microscopy, high resolution transmission electron microscopy, and energy dispersive X-ray spectroscopy were obtained by using JEOL2100F (200 kV); high angle annular dark field electron microscopy was obtained by employing FEI THEMIS Z.
The synthesis schematic diagram of La 2IrO6/IrO2 is shown in figure 1, and the calcined electrostatic spinning precursor product is treated by hydrochloric acid to obtain a pure La 2IrO6/IrO2 catalyst. XRD testing of the calcined catalyst precursor was performed, and as shown in FIG. 2, by comparing XRD diffraction peaks, it was found that the calcined material had a multi-phase composition, including La 2IrO6、IrO2 and LaOCl. By SEM characterization of the calcined product, as shown in fig. 3 (a-c), SEM and TEM results indicate that electrospinning was successful, the precursor material exhibited a predominantly tubular structure with both particulate and bulk impurities present, consistent with XRD results. To further investigate the composition of the precursor material, HRTEM analysis was performed on bulk impurities in the precursor material, as shown in fig. 3 (d-f), with a fringe spacing of 0.36 nm, consistent with the (101) crystal plane of LaOCl, indicating that the bulk impurities had a main composition of LaOCl. Further investigation of the composition of the material attached to the nanotube was also conducted, and as shown in FIG. 3 (g-i), the lattice fringe spacing of the particles attached to the tube wall was 0.32nm and 0.26 nm, respectively, which were consistent with the (110) and (101) crystal planes of IrO 2, indicating that these particles attached to the tube wall consisted of IrO 2. In combination with the above conclusion, it can be found that the precursor material is obviously not a single La 2IrO6/IrO2 heterojunction structure. Therefore, we further propose a purification treatment with hydrochloric acid to obtain the La 2IrO6/IrO2 heterojunction structure.
By varying the time for which the precursor material is immersed in hydrochloric acid, it was found that the hydrochloric acid treatment time is critical to the extent of purification of the precursor. XRD tests were performed on samples with different hydrochloric acid treatment times, as shown in fig. 4, with the increase of the treatment time, the diffraction peak signals at the 2θ angles of 12.8 °,30.7 ° and 34 ° were significantly reduced, which indicates that the content of LaOCl in the sample was significantly reduced during the hydrochloric acid treatment, and after the treatment time reached 16 h, the diffraction peak signals of LaOCl were completely disappeared, which indicates that LaOCl was completely removed. To ensure complete removal of LaOCl, samples with a hydrochloric acid treatment time of 20h were taken for subsequent investigation.
By XRD analysis of the purified sample, as in fig. 5, it was found that IrO 2 phase was present in the purified sample and that the remaining diffraction peaks were also consistent with the La 2IrO6 diffraction peaks reported in the literature, indicating that La 2IrO6/IrO2 catalyst material was successfully synthesized.
To further investigate the structure of the purified catalyst, SEM and TEM of La 2IrO6/IrO2 catalyst were shown in fig. 6 (a-b), la 2IrO6/IrO2 catalyst was represented as smooth nano-tubular structure, and by analysis of La 2IrO6/IrO2 HRTEM, as shown in fig. 6 (c), lattice fringe spacing was 0.278 nm, 0.256 nm and 0.319 nm, corresponding to (112) crystal face of La 2IrO6 and (101) and (110) crystal faces of IrO 2, respectively, indicating that there was a distinct heterojunction interface between La 2IrO6 and IrO 2, which is a catalyst with heterojunction characteristics. Further, the elemental distribution of La 2IrO6/IrO2 is shown in fig. 6 (d), indicating that the La, ir, O elements are uniformly distributed in the catalyst. In order to confirm the effect of hydrochloric acid treatment purification on the electronic structure of La 2IrO6/IrO2, XPS test was performed on La 2IrO6/IrO2, and as shown in fig. 7, the signal of Cl 2p of La 2IrO6/IrO2 completely disappeared compared with the sample not subjected to hydrochloric acid treatment, indicating that the catalyst does not contain chlorine element, which is consistent with the XRD result, demonstrating that the effect of hydrochloric acid purification treatment on LaOCl removal is remarkable. In addition, la 2IrO6/IrO2 did not shift the Ir 4f spectrum position compared to the sample before purification, indicating that hydrochloric acid treatment did not alter the structural properties of La 2IrO6/IrO2. Meanwhile, by comparing the Ir 4f spectrogram of La 2IrO6/IrO2 with the Ir 4f spectrogram of commercial IrO 2, the Ir 4f in La 2IrO6/IrO2 has higher binding energy as a whole and higher valence state of Ir, which indicates that La 2IrO6/IrO2 has iridium atoms higher than 4+, which also proves that the iridium atoms with high valence state exist stably are successfully synthesized.
Example 3: electrochemical testing of La 2IrO6/IrO2 catalyst materials
All electrochemical tests in the work are completed in a 0.5M H 2SO4 solution environment, and the instrument used for the tests is Shanghai Chenhua CHI 760E. In the three-electrode system used in the test, the counter electrode is a platinum sheet electrode, the working electrode is carbon paper coated with a catalyst material, the size of the working electrode is 0.5 cm multiplied by 2 cm, and the calomel electrode is used as a reference electrode (SCE). In all electrochemical tests, the electrode potential was converted to a Reversible Hydrogen Electrode (RHE) by E vs.RHE= Evs.SCE +0.264V.
When the working electrode is prepared, weighing 4 mg catalyst materials and a 1.5ml centrifuge tube, adding 1 mL deionized water, performing ultrasonic treatment for 30min to obtain uniformly dispersed turbid liquid, sucking 10 mu L of uniformly dispersed turbid liquid through a pipette, coating the uniformly dispersed turbid liquid at the tail end of carbon paper, drying in a drying oven, coating 5 mu L of 0.2% Nafion solution again, and drying again to obtain the working electrode. By calculation, the working electrode catalyst loading used in this work was 0.56 mg cm -2.
In the electrochemical test, a linear volt-ampere curve is obtained under the sweeping speed condition of 10 mvs -1, and 90% iR compensation correction is carried out on each curve; cyclic voltammograms in the electrochemically active areas were obtained at sweep rates of 10, 20, 30, 40, 50 mv s -1, respectively; the frequency range of electrochemical impedance spectroscopy measurement was 100 kHz to 0.01 Hz, the potential was 1.3V, and the amplitude potential was 5 mV. The current density for the catalyst test in the chronovoltammetry method was 10 mAcm -2.
In a conventional three-electrode system, a series of electrochemical performance tests were performed on the catalyst. Polarization curve tests were first performed on different catalysts, such as commercial IrO 2 catalyst (IrO 2 -C), electrospun prepared IrO 2 nanowires (IrO 2 -ES), and La 2IrO6/IrO2, and the overpotential at a current density of 10 mAcm -2 was typically used to evaluate the catalyst for catalytic activity. A smaller overpotential represents a better catalytic activity of the catalyst.
As shown in fig. 8 (a), la 2IrO6/IrO2 showed the best catalytic performance with the least overpotential among several catalysts, which was 279 mV only. Meanwhile, the overpotential of La 2IrO6/IrO2 is smaller than that of commercial IrO 2, which shows that La 2IrO6/IrO2 has good commercial application potential. The tafel slope curve can be obtained by fitting the polarization curve, as shown in fig. 8 (b), and the tafel slope of La 2IrO6/IrO2 is the smallest, which indicates that La 2IrO6/IrO2 has faster OER reaction kinetics, and is beneficial to the OER reaction. To investigate the intrinsic catalytic activity of the La 2IrO6/IrO2 catalyst, the mass activity of La 2IrO6/IrO2 was calculated from the LSV curve, as shown in fig. 9 (a-b), the mass activity of La 2IrO6/IrO2 was far better than that of the commercial IrO 2 catalyst, and at an overpotential of 300 mV, the mass activity of La 2IrO6/IrO2 was about 5 times as high as that of the commercial IrO 2 catalyst, further proving that La 2IrO6/IrO2 is a potential acidic OER catalyst. La 2IrO6/IrO2 not only has excellent acidic OER catalytic activity, but also exhibits excellent catalytic stability. As shown in fig. 10, the stability of La 2IrO6/IrO2 was tested by chronopotentiometry, la 2IrO6/IrO2 was continuously and stably operated at a current density of 10 mAcm -2 over 80 h, the catalytic performance was hardly attenuated, and IrO 2 was drastically reduced under this condition for only a few hours. From this, la 2IrO6/IrO2 can be demonstrated to have not only excellent OER catalytic activity, but also excellent OER catalytic stability, demonstrating that La 2IrO6/IrO2 is a very potential oxygen evolution reaction catalyst.
The electrochemical activity specific surface area of all catalysts was evaluated by electrochemical double layer capacitance based on electrochemical cyclic voltammetry, so that the reason why La 2IrO6/IrO2 has excellent catalytic activity was briefly revealed. As shown in FIG. 11 (c), la 2IrO6/IrO2 had an electrochemically active area higher than IrO 2 -ES, indicating that La 2IrO6/IrO2 exposed more active sites in the OER reaction. And in the multi-step amperometric test of fig. 12, la 2IrO6/IrO2 increased stepwise with current density, the overpotential also increased uniformly, indicating that La 2IrO6/IrO2 also had excellent charge transfer kinetics.
Electrochemical impedance spectroscopy is also commonly used to explore the reaction mechanism of the catalyst. The catalyst was subjected to EIS testing at OER potential (1.3V vs. Ag/AgCl) as shown in FIG. 13 (a). Analysis of the nyquist plot revealed a smaller charge transfer resistance (Rct) in the low frequency region La 2IrO6/IrO2, indicating that La 2IrO6/IrO2 has faster charge transfer kinetics; la 2IrO6/IrO2 also has faster diffusion kinetics in the high frequency region. Furthermore, as shown in fig. 13 (b), analysis of EIS phase diagram, la 2IrO6/IrO2 has a lower phase angle and shifts to higher frequency than IrO 2 -ES, demonstrating that La 2IrO6/IrO2 has a stronger adsorption capacity for OER intermediate OH and a faster deprotonation rate in OER reactions.
The foregoing disclosure is illustrative of the present invention and is not to be construed as limiting the scope of the invention, which is defined by the appended claims.
Claims (7)
1. A catalyst material characterized by: the hollow nano-tubular structure with heterojunction characteristics is formed by compounding La 2IrO6 and IrO 2.
2. The method for preparing a catalyst material according to claim 1, characterized by comprising the steps of:
(1) Dissolving La (NO 3)3·6H2 O and K 2IrCl6 in a mixed solution of ethanol and N, N-dimethylformamide to obtain a precursor solution;
(2) Adding a spinning aid into the precursor solution to obtain a spinning solution;
(3) Spinning the spinning solution through an electrostatic spinning device to obtain a La 2IrO6/IrO2/LaOCl precursor;
(4) Calcining the La 2IrO6/IrO2/LaOCl precursor in air to obtain La 2IrO6/IrO2/LaOCl nanotube;
(5) And purifying the La 2IrO6/IrO2/LaOCl nanotube obtained by calcination by using hydrochloric acid to obtain the La 2IrO6/IrO2 nanotube.
3. The method for producing a catalyst material according to claim 2, characterized in that: in step (1), la (molar ratio of NO 3)3·6H2 O to K 2IrCl6 was 1:1.
4. The method for producing a catalyst material according to claim 2, characterized in that: in the step (2), the spinning aid is polyvinylpyrrolidone.
5. The method for producing a catalyst material according to claim 2, characterized in that: in step (4), the calcination temperature was 750 ℃.
6. The method for producing a catalyst material according to claim 2, characterized in that: in step (5), the hydrochloric acid treatment time is at least 16 hours.
7. Use of the catalyst material according to claim 1 as an anode oxygen evolution reaction catalyst.
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| CN113398923A (en) * | 2021-05-24 | 2021-09-17 | 北京化工大学 | Carbon-supported IrO2@ Ir heterojunction composite catalyst with strawberry-shaped structure and preparation method and application thereof |
| KR20220076414A (en) * | 2020-11-30 | 2022-06-08 | 한국과학기술원 | Iridium Oxide-Based Electrocatalyst and Preparation Method Thereof |
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| KR20220076414A (en) * | 2020-11-30 | 2022-06-08 | 한국과학기술원 | Iridium Oxide-Based Electrocatalyst and Preparation Method Thereof |
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