High-entropy metaphosphate catalyst as well as preparation method and application thereof
By using a high-entropy metaphosphate catalyst preparation method, the problem of low efficiency of existing ORR catalysts in the three-electron oxygen reduction reaction is solved, achieving high efficiency in the degradation of organic dyes and catalyst stability, which is suitable for fuel cells and electrochemical degradation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG UNIV OF TECH
- Filing Date
- 2026-02-09
- Publication Date
- 2026-05-26
AI Technical Summary
Existing ORR catalysts suffer from low efficiency and catalyst corrosion in the three-electron oxygen reduction reaction, especially in fuel cells where H2O2 accumulation leads to reduced efficiency.
A one-step calcination method using high-entropy metaphosphate catalysts was developed. This method involves reacting ammonium phosphate salts and metal salts at 800°C for 2 hours in an air atmosphere to form a high-entropy metaphosphate catalyst, which is then used for the degradation of organic dyes via three-electron oxygen reduction reaction.
It achieves a highly efficient three-electron oxygen reduction reaction, degrading organic dyes while avoiding H2O2 accumulation, thus improving the stability and reaction kinetics of the catalyst and making it suitable for large-scale production.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of ORR catalytic materials, specifically to a high-entropy metaphosphate catalyst and its preparation method, as well as its application in the degradation of organic dyes by three-electron oxygen reduction reaction. Background Technology
[0002] The oxygen reduction reaction (ORR) is one of the core reactions in energy conversion and storage fields (such as fuel cells and metal-air batteries). Traditionally, the ORR mainly follows a four-electron pathway (O₂ + 4H₂O) in acidic or alkaline electrolytes. + + 4e - → 2H₂O or O₂ + 2H₂O + 4e - → 4OH - ORR can achieve direct and efficient conversion of oxygen molecules to water with high energy utilization. However, under certain material or reaction conditions, ORR can partially generate hydrogen peroxide (H2O2) intermediates via a two-electron pathway. Although this pathway can be used for the electrosynthesis of H2O2, it can lead to reduced efficiency and catalyst corrosion in fuel cells.
[0003] In recent years, the three-electron oxygen reduction reaction (3e...) has become increasingly important. - ORR (oral regeneration response) has attracted attention as an intermediate mechanism, with the reaction pathway being O2 + 2H+. + + 2e - → H2O2 and H2O2 + 2H + + 2e - → The coupling of 2H₂O results in a total of 4 electrons, but if only the first half (generating H₂O₂) occurs, it results in 2 electrons. If H₂O₂ is further completely reduced, it will have 4 electrons. Strictly speaking, "three-electron ORR" usually refers to the process where oxygen molecules directly generate intermediates such as hydroxyl radicals through three steps of single-electron transfer, or the direct conversion of O₂ to H₂O and OH⁻ on the surface of a special catalyst. - The 3-electron pathway, such mechanisms, can be used in catalytic design to adjust reaction selectivity, avoid H2O2 accumulation, and maintain high reaction kinetics.
[0004] Phosphate materials (such as transition metal phosphates and carbon phosphorylation materials) exhibit unique advantages in regulating ORR pathways, especially in promoting efficient and stable three-electron ORR processes. Specifically, they possess tunable surface electronic structures, excellent stability and corrosion resistance, and low cost and environmental friendliness. Therefore, reducing energy consumption, saving costs, simplifying synthesis processes, and rationally designing transition metal phosphate materials with excellent electrochemical performance are urgent priorities. Here, we propose a simple and rapid one-step calcination method to synthesize metaphosphates for electrocatalytic performance testing and electrochemical degradation of pollutants. Summary of the Invention
[0005] The purpose of this invention is to provide a novel high-entropy metaphosphate catalyst, its preparation method, and its applications. This invention has advantages such as simple process and equipment, low energy consumption, and ease of large-scale production.
[0006] The technical solution of the present invention is as follows: A method for preparing a high-entropy metaphosphate catalyst, comprising: Using ammonium phosphate as the P source and metal salt as the structure control agent, the mixture was ground and transferred to a crucible. The crucible was then placed in a muffle furnace and heated to 800°C for 2 hours in an air atmosphere to obtain the high-entropy metaphosphate catalyst. Ammonium polyphosphate is preferred over ammonium phosphate. The metal salt is selected from one or more of cobalt nitrate hexahydrate, nickel nitrate hexahydrate, ferric nitrate nonahydrate, copper nitrate trihydrate, and manganese nitrate tetrahydrate; The preferred metal salt is a mixture of cobalt nitrate hexahydrate and nickel nitrate hexahydrate, and the mass ratio of ammonium polyphosphate, cobalt nitrate hexahydrate, and nickel nitrate hexahydrate is 1:0.3:0.317; Alternatively, the preferred metal salt is a mixture of cobalt nitrate hexahydrate, nickel nitrate hexahydrate, ferric nitrate nonahydrate, copper nitrate trihydrate, and manganese nitrate tetrahydrate, and the mass ratio of ammonium polyphosphate, cobalt nitrate hexahydrate, nickel nitrate hexahydrate, ferric nitrate nonahydrate, copper nitrate trihydrate, and manganese nitrate tetrahydrate is 1:0.1:0.101:0.147:0.772:0.0927.
[0007] This invention relates to the high-entropy metaphosphate catalyst prepared by the above-described preparation method.
[0008] The high-entropy metaphosphate catalyst described in this invention can be used for the degradation of organic dyes, such as methyl orange, via a three-electron oxygen reduction reaction.
[0009] Compared with the prior art, the present invention has the following beneficial effects: The raw materials used are readily available, the preparation method is simple and reproducible, which is beneficial for the large-scale production of metaphosphate catalysts. The high-entropy metaphosphate catalyst prepared by this invention is suitable for the degradation of organic dyes such as methyl orange by the three-electron oxygen reduction reaction. Attached Figure Description
[0010] Figure 1 XRD patterns of the catalyst materials prepared in Examples 1-3 of this invention.
[0011] Figure 2 SEM image of CoMPi prepared in Example 1 of this invention.
[0012] Figure 3SEM image of CoNiMPi prepared in Example 2 of this invention.
[0013] Figure 4 SEM image of HEMPi prepared in Example 3 of this invention.
[0014] Figure 5 TEM image of CoMPi prepared in Example 1 of this invention.
[0015] Figure 6 TEM image of CoNiMPi prepared in Example 2 of this invention.
[0016] Figure 7 TEM image of HEMPi prepared in Example 3 of this invention.
[0017] Figure 8 XPS image of CoMPi prepared in Example 1 of this invention (M represents a metal element).
[0018] Figure 9 XPS image of CoNiMPi prepared in Example 2 of this invention.
[0019] Figure 10 XPS image of HEMPi prepared in Example 3 of this invention.
[0020] Figure 11 LSV performance curves of the catalyst materials prepared in Examples 1-3 of this invention in 0.1M KOH solution for ORR (n represents the number of electrons transferred in the ORR reaction).
[0021] Figure 12 EPR curve of CoMPi prepared in Example 1 of this invention.
[0022] Figure 13 EPR curve of CoNiMPi prepared in Example 2 of this invention.
[0023] Figure 14 EPR curve of HEMPi prepared in Example 3 of this invention.
[0024] Figure 15 Degradation performance of the catalyst materials prepared in Examples 1-3 of this invention in 0.1M KOH solution containing 20ppm methyl orange. Detailed Implementation
[0025] The present invention is further described below through specific embodiments, but the scope of protection of the present invention is not limited thereto.
[0026] In the following examples, ammonium polyphosphate was purchased from Maclean Chemical Reagent Co., Ltd. (NH4PO3) n(n < 20, water solubility > 90 g / 100 ml)
[0027] Example 1: CoMPi
[0028] Ammonium polyphosphate (1 g) and cobalt nitrate hexahydrate (0.3 g) were mixed and ground for 5 minutes, then transferred to a crucible. The crucible was placed in a muffle furnace and heated to 800 °C (heating rate 5 °C / min) in air for 2 hours to obtain CoMPi. The crystalline phase analysis is as follows: The crystalline phases of CoMPi were analyzed using powder X-ray diffraction (XRD), and the results are as follows: Figure 1 As shown, the synthesized material corresponds to the characteristic peaks of the cobalt metaphosphate standard card, indicating that the metaphosphate was successfully synthesized.
[0029] Surface analysis is as follows: The surface morphology of the material was observed using a scanning electron microscope (SEM), and the results are as follows: Figure 2 As shown, CoMPi has a blocky structure with an uneven surface and a large surface area.
[0030] Transmission electron microscopy analysis is as follows: The material surface was observed using a transmission electron microscope (TEM), and the results are as follows: Figure 5 As shown, the material exhibits a blocky structure with small dimensions on its surface, and the three elements Co, P, and O are uniformly distributed on the surface.
[0031] The X-ray photoelectron spectroscopy analysis is as follows:
[0032] The material structure was analyzed using X-ray photoelectron spectroscopy, and the results are as follows: Figure 8 As shown. This material contains PO, MO bonds and PO3. - XPS plots of Co show that it possesses a two-state spin orbital configuration of 2p1 / 2 and 2p3 / 2, as well as characteristic features of Co. 2+ Satellite peaks (as shown in Sat).
[0033] Electron paramagnetic resonance (EPR) spectroscopy analysis is as follows: Electron paramagnetic resonance spectroscopy was used to detect hydroxyl radicals in different material systems. The signal of OH) and the result are as follows Figures 12-14As shown, CoMPi has a weaker signal, thus exhibiting the weakest activity in the 3e-ORR reaction, while CoNiMPi and HEMPi show very strong signals, indicating that these two materials will have higher catalytic activity in the 3e-ORR reaction.
[0034] Electrochemical performance testing: Preparation of catalyst ink: 5 mg of catalyst sample was dispersed in 700 μL of deionized water, 250 μL of ethanol, and 50 μL of Nafion (5 wt%) to form catalyst ink.
[0035] Electrochemical tests were performed using a traditional three-electrode electrochemical workstation (CHI 760E), with a Pt wire as the counter electrode, a glassy carbon electrode coated with the catalyst ink as the working electrode, and an Ag-AgCl (saturated potassium chloride solution) electrode as the reference electrode.
[0036] All potentials were calibrated relative to the reversible hydrogen electrode (RHE) using the following calculation: E(vs. RHE) = E(vs. Ag-AgCl) + 0.222 + 0.059 pH. All polarization profiles were corrected for 95% IR compensation.
[0037] Linear sweep voltammetry (LSV) was performed with 0.1 M KOH solution as the electrolyte. The results are as follows: Figure 11 As shown, the half-wave potential of CoMPi is 0.7V, and its response is closer to 4e-ORR.
[0038] Electrochemical degradation test of methyl orange dye: The solution was a 0.1M KOH solution containing 20 ppm methyl orange.
[0039] Preparation of catalyst ink: 5 mg of catalyst sample was dispersed in 700 μL of deionized water, 250 μL of ethanol, and 50 μL of Nafion (5 wt%) to form catalyst ink.
[0040] The degradation test also used a traditional three-electrode electrochemical workstation (CHI 760E), with a Pt wire as the counter electrode, a glassy carbon electrode coated with catalyst ink as the working electrode, and an Ag-AgCl (saturated potassium chloride solution) electrode as the reference electrode.
[0041] Electrolysis was performed under saturated oxygen conditions with an applied potential of 4V. The resulting solution was then tested to determine the concentration of methyl orange. Figure 15 As shown, the degradation performance of the CoMPi catalyst is significantly lower than that of the other two catalysts.
[0042] Example 2: CoNiMPi
[0043] Ammonium polyphosphate (1g), cobalt nitrate hexahydrate (0.3g), and nickel nitrate hexahydrate (0.317g) were mixed and ground for 5 minutes, then transferred to a crucible. The crucible was placed in a muffle furnace and heated to 800℃ (heating rate 5℃ / min) in air atmosphere for 2 hours to obtain CoNiMPi.
[0044] Its surface morphology is as follows Figure 3 As shown, its surface also has an uneven, blocky structure, as seen in transmission electron microscopy images. Figure 6 It was also observed to have a blocky structure. Structural analysis is as follows: Figure 9 As shown, this material contains PO, MO bonds and PO3. - The XPS plots of Co and Ni show that they possess two spin-orbit states coiled into 2p1 / 2 and 2p3 / 2, as well as characteristic Co and Ni satellite peaks (as shown in Sat). EPR tests are as follows. Figure 13 As shown in the figure, it can be seen that it has a high EPR signal intensity. Electrocatalytic ORR performance testing is as follows: Figure 11 As shown, its half-wave potential was measured to be 0.61 V, and its reaction is closer to 3e-ORR. Electrochemical degradation of methyl orange dye, as shown... Figure 15 As shown, the degradation rate can reach 99% in 50 minutes.
[0045] Example 3: HEMPi
[0046] Ammonium polyphosphate (1g), cobalt nitrate hexahydrate (0.1g), nickel nitrate hexahydrate (0.101g), ferric nitrate nonahydrate (0.147g), copper nitrate trihydrate (0.772g), and manganese nitrate tetrahydrate (0.0927g) were mixed and ground for 5 minutes, then transferred to a crucible. The crucible was placed in a muffle furnace and heated to 800℃ (heating rate 5℃ / min) in air atmosphere for 2 hours to obtain HEMPi.
[0047] Its surface morphology is as follows Figure 4 The image also shows an uneven, blocky structure, as seen in transmission electron microscopy (TEM) images. Figure 7 It was observed to have a blocky structure. Structural analysis is as follows: Figure 10 As shown, this material contains PO, MO bonds and PO3. - XPS plots of Fe, Co, Ni, Cu, and Mn show their characteristic spin-orbit dual states, coiled into 2p¹ / ² and 2p³ / ² spin orbitals, as well as the characteristic Fe, Co, Ni, Cu, and Mn satellite peaks (as shown in Sat). EPR tests are as follows... Figure 14 As shown in the figure, it can be seen that it has a high EPR signal intensity. Electrocatalytic ORR performance testing is as follows: Figure 11 As shown, its half-wave potential was measured to be 0.608V, and its response is closer to 3e-ORR. EPR testing is as follows... Figure 13As shown, it exhibits a high EPR signal intensity. Electrochemical degradation of methyl orange dye, such as... Figure 15 As shown, the degradation rate can reach 99% in 50 minutes.
Claims
1. A method for preparing a high-entropy metaphosphate catalyst, characterized in that, include: Using ammonium phosphate as the P source and metal salt as the structure control agent, the mixture was ground and transferred to a crucible. The crucible was then placed in a muffle furnace and heated to 800°C for 2 hours in an air atmosphere to obtain the high-entropy metaphosphate catalyst. The metal salt is selected from one or more of cobalt nitrate hexahydrate, nickel nitrate hexahydrate, ferric nitrate nonahydrate, copper nitrate trihydrate, and manganese nitrate tetrahydrate.
2. The preparation method according to claim 1, characterized in that, Ammonium phosphate salt is ammonium polyphosphate.
3. The preparation method according to claim 1, characterized in that, The ammonium phosphate salt is ammonium polyphosphate, and the metal salt is a mixture of cobalt nitrate hexahydrate and nickel nitrate hexahydrate.
4. The preparation method according to claim 3, characterized in that, The mass ratio of ammonium polyphosphate, cobalt nitrate hexahydrate, and nickel nitrate hexahydrate is 1:0.3:0.
317.
5. The preparation method according to claim 1, characterized in that, The ammonium phosphate salt is ammonium polyphosphate, and the metal salt is a mixture of cobalt nitrate hexahydrate, nickel nitrate hexahydrate, ferric nitrate nonahydrate, copper nitrate trihydrate, and manganese nitrate tetrahydrate.
6. The preparation method according to claim 5, characterized in that, The mass ratio of ammonium polyphosphate, cobalt nitrate hexahydrate, nickel nitrate hexahydrate, ferric nitrate nonahydrate, copper nitrate trihydrate, and manganese nitrate tetrahydrate is 1:0.1:0.101:0.147:0.772:0.0927.
7. The high-entropy metaphosphate catalyst prepared by the preparation method according to any one of claims 1 to 6.
8. The application of the high-entropy metaphosphate catalyst as described in claim 7 in the degradation of organic dyes by three-electron oxygen reduction reaction.