A high-exposure (111) prussian blue analogue catalyst and preparation and application thereof
By synthesizing a CoFe PBA catalyst with highly exposed (111) crystal planes via a hydrothermal method, the problem of balancing catalyst activity, selectivity and stability in the prior art is solved, and the effect of efficient electrosynthesis of hydrogen peroxide is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FUZHOU UNIV
- Filing Date
- 2026-04-01
- Publication Date
- 2026-06-16
AI Technical Summary
Existing catalysts struggle to achieve a balance between high activity, high selectivity, and high stability during the electrosynthesis of hydrogen peroxide, and existing methods for controlling the crystal facets of Prussian blue catalysts are not simple or controllable enough.
A Prussian blue-like catalyst with highly exposed (111) crystal planes was synthesized by hydrothermal method. By controlling the hydrothermal reaction temperature and component ratio, a CoFe PBA catalyst with a truncated octahedral structure was prepared. The electronic structure of the metal center was regulated to moderately adsorb *OOH, thereby achieving efficient electrosynthesis of H2O2.
It achieved high selectivity (98.75%) and high stability (no significant deactivation after 50 h), and exhibited excellent 2e–ORR electrocatalytic performance in both rotating ring disk electrode and gas diffusion electrode, with H2O2 production rate of 7.72 mol gcat.-1h-1 and 100% Faraday efficiency.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of energy catalysis, specifically relating to a Prussian blue-like catalyst with high exposure of (111) crystal planes, its preparation, and its application in the electrocatalytic two-electron oxygen reduction (2e... – Application of ORR in the synthesis of hydrogen peroxide. Background Technology
[0002] Hydrogen peroxide (H₂O₂) is an important green oxidant widely used in chemical synthesis, wastewater treatment, and pulp bleaching. Currently, the anthraquinone process is the main industrial method for producing H₂O₂. While this process allows for large-scale production, it cannot avoid high energy consumption and poses an explosion risk during the production, transportation, and storage of large amounts of organic waste, which does not meet the requirements of green chemistry development. The electrochemical two-electron oxygen reduction reaction (2e⁻² ... – Direct synthesis of H2O2 (ORR) is considered a promising alternative route due to its low energy consumption, environmental friendliness, and immediate usability. Therefore, developing an efficient, inexpensive, and highly selective H2O2 synthesis method is crucial. – ORR electrocatalysts have become a research hotspot in this field.
[0003] In recent years, transition metal-based electrocatalysts have attracted much attention from researchers due to their excellent performance and low cost. Published literature ( Chem (2020, 6, 658) indicates that among many transition metals, Co-based catalysts exhibit moderate adsorption with *OOH, thus achieving 100% H2O2 selectivity. As reported in most studies, Co shows weak activation for O2, exhibiting low activity. Fe-based catalysts, due to their strong adsorption with O2, demonstrate high ORR activity. Published literature ( Energy Environ. Sci., (2019, 12, 2548-2558) indicates that Fe-NC catalysts prepared using zinc-based zeolite imidazole (ZIF-8) as a precursor exhibit high ORR activity due to their strong adsorption to O2, and can reduce the ORR half-wave potential (E) to 2548-2558. 1 / 2 Increased to 0.88 V vs. RHE, however, cannot achieve high H2O2 selectivity due to its strong adsorption with *OOH. Furthermore, highly active sites are prone to irreversible oxidation or dissolution during the reaction, leading to decreased stability, while low-activity sites exhibit the opposite performance. Nat. Catal. (2025, 8, 417). Therefore, a 2e-type ion with high activity, high selectivity, and high stability is designed. – ORR catalysts are urgently needed.
[0004] Studies have shown that there is a significant structure-activity relationship between the exposed crystal facets of a catalyst and its catalytic performance. Catalysts with different exposed crystal facets directly determine the degree of exposure of catalytic active sites, the mass transfer pathway of reactants / products, and electronic structure characteristics, thus leading to significant differences in catalytic performance. (Published literature...) J. Am. Chem. Soc. 2023, 145, 7791- 7799 This indicates that, compared to ZnCo ZIF with exposed (110) crystal faces, the Co centers in ZnCo ZIF with exposed (100) crystal faces are adjusted to electron-deficient centers, exhibiting moderate adsorption of reaction intermediates. Simultaneously, it promotes the protonation of H2O and the desorption of *HOOH, improving the H2O2 selectivity (100%) and the H2O2 preparation rate (4.35 mol g). cat. -1 h -1 However, this catalyst only achieves stability for 2 hours, still failing to achieve a balance between high activity, high selectivity, and high stability. (Published literature...) Adv. Mater, 2025, 37, 2500250 A method combining liquid metal-assisted chemical vapor deposition and high-temperature calcination was disclosed to obtain two MoP catalysts with different exposed crystal faces: nanosheets and nanopillars. Among them, the nanopillar MoP improved the selectivity (92%) and stability (80 h) of H2O2 compared with the nanosheets by reducing the adsorption strength of *OOH. However, the synthesis process of this method is complicated and the high-temperature calcination has certain risks.
[0005] Prussian blue-like (PBA) catalysts are ideal electrocatalytic materials due to their well-defined lattice structure, tunable metal centers, high specific surface area, and adjustable exposed crystal faces. In existing technologies, PBA catalysts are mostly prepared using co-precipitation methods, resulting in PBA with predominantly (100) crystal faces and relatively low exposure of the highly active (111) face. Furthermore, the lack of simple and controllable methods for crystal facet manipulation makes it difficult to simultaneously achieve both selectivity and catalytic activity for H2O2. Meanwhile, existing technology (CN119040942A) discloses the preparation of oxygen-rich vacancy- and surface-cyano-modified transition metal oxides using PBA as a precursor via alkaline etching, which are then used for 2e... – ORR electrocatalytic production of hydrogen peroxide utilizes defect engineering to modify metal oxides and enhance catalytic performance. However, the resulting product is a transition metal oxide, not the Prussian blue-like catalyst itself, and it does not involve the crystal facet control of the Prussian blue-like catalyst, thus failing to achieve crystal facet control for 2e⁻. – Targeted optimization of ORR performance. Summary of the Invention
[0006] The purpose of this invention is to overcome the shortcomings of existing catalysts that cannot achieve a balance of high activity, high selectivity and high stability in the electrosynthesis of H2O2, and the difficulty in precisely controlling the exposed crystal facets in the existing synthesis methods for preparing Prussian blue catalysts. The invention proposes a Prussian blue-like catalyst with high exposure of (111) crystal facets and its preparation method.
[0007] To achieve the above objectives, the present invention adopts the following technical solution: A Prussian blue-like catalyst with high exposure of (111) crystal facets, which is a truncated octahedron with a size of about 250 nm and an (111) crystal facet exposure of more than 14%, helps to adjust the electronic structure of the metal center to achieve moderate *OOH adsorption, thereby achieving efficient and stable electrosynthesis of H2O2.
[0008] The preparation method of the Prussian blue-like catalyst with high exposure (111) crystal plane includes the following steps: 1) Dissolve soluble cobalt salt and sodium citrate dihydrate in water to prepare solution A; dissolve potassium ferricyanide in water to prepare solution B; under stirring conditions, quickly pour solution B into solution A, mix evenly, and then transfer the resulting mixture to a polytetrafluoroethylene liner for hydrothermal precipitation. 2) The product obtained in step 1) was ultrasonically cleaned three times with deionized water and ethanol respectively. After centrifugation, the product was collected and placed in a vacuum oven and dried at 60 °C for 12 h to obtain the Prussian blue-like catalyst with high exposure (111) crystal plane.
[0009] Further, the soluble cobalt salt mentioned in step 1) is any one of cobalt nitrate, cobalt acetate, and cobalt chloride.
[0010] Further, the mass ratio of the soluble cobalt salt to sodium citrate dihydrate used in step 1) is (1~3):(3~1).
[0011] Further, in step 1), the molar ratio of Co to Fe in the mixture is (1~10):(10~1).
[0012] Further, the temperature of the hydrothermal precipitation in step 1) is 0 ℃~140 ℃ (preferably 90 ℃), and the time is 12~24 h.
[0013] The Prussian blue-like catalyst with highly exposed (111) crystal planes can be used for the electrocatalytic two-electron oxygen reduction (2e... – The reaction for preparing hydrogen peroxide (ORR) is mild, highly selective, and the cathode catalyst is highly stable for H2O2.
[0014] Furthermore, its application method specifically includes the following steps: 1) Polish the suede with 0.05 μm Al2O3 powder until it is mirror-finished, then rinse it with deionized water to remove physically adsorbed particles, and then blow it dry with argon to obtain the initial electrode. 2) Add 1 mL of isopropanol to 10 mg of Prussian blue-like catalyst, sonicate for 1 h, then add 35 μL of 5 wt% Nafion proton exchange membrane solution, and sonicate for another 30 min to obtain a homogeneous slurry; under an infrared lamp, use a pipette to evenly drop 10 μL of the slurry onto a working area of 0.2475 cm². 2 Working electrode 1 is fabricated on the initial electrode; 20 μL of slurry is uniformly drop-coated onto a working area of 1 × 1 cm. 2 The working electrode 2 is fabricated on hydrophobic carbon paper; 3) Using Pt wire as the counter electrode, Ag / AgCl as the reference electrode, alkaline solution as the electrolyte, and working electrode 1 obtained in step 2) to form a three-electrode system, an external voltage is applied in the rotating ring disk electrode test system to perform electrochemical catalytic oxygen reduction test. 4) Using a Pt sheet as the counter electrode, Ag / AgCl as the reference electrode, and an alkaline solution as the electrolyte, a three-electrode system is formed with the working electrode 2 obtained in step 2). An electrochemical catalytic oxygen reduction test is performed in a gas diffusion electrode electrolytic cell with an external constant current applied.
[0015] Furthermore, the electrolyte mentioned in steps 3) and 4) is an oxygen-saturated potassium hydroxide solution with a concentration of 0.1 mol / L.
[0016] Furthermore, in step 3), when conducting the test in the rotating ring-disc electrode test system, the voltage on the disk electrode is 0.2 ~ 0.8 V. vs. RHE, the voltage applied to the ring electrode is 1.5 V. vs. RHE.
[0017] Furthermore, in step 4), when conducting the test in the gas diffusion electrode electrolytic cell, the constant current used is -10 to -90 mA cm⁻¹. –2 The flow rate is 2~10 mL / min. –1 The reaction time is 1~24 h.
[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The method for preparing Prussian blue-like catalysts in this invention is simple and easy to implement, and the product can be obtained by hydrothermal treatment in just one step.
[0019] (2) The active component of the CoFe-type Prussian blue (CoFe PBA) obtained in this invention is a non-precious metal, which has the advantages of being inexpensive, readily available, and abundant in nature.
[0020] (3) This invention effectively controls the metal valence state of the catalyst through crystal plane engineering strategy, thereby achieving appropriate *OOH adsorption, which greatly improves the selectivity and activity of the Prussian blue-like catalyst, making it exhibit excellent 2e – The ORR electrocatalytic performance achieves 98.75% H2O2 selectivity in the rotating ring-disc electrode system and 7.72 mol g in the gas diffusion electrode system. cat. -1 h -1 The H2O2 production rate is 100% Faraday efficiency.
[0021] (4) The Prussian blue-like catalyst obtained in this invention did not show significant deactivation after reacting in a gas diffusion electrode for 50 h, indicating high catalyst stability.
[0022] (5) Electrocatalysis of 2e using the Prussian blue catalyst of the present invention – The process for preparing hydrogen peroxide using ORR is simple, the conditions are mild, and it is conducive to industrial production. Attached Figure Description
[0023] Figure 1 The XRD patterns of CoFe PBA prepared in the examples and comparative examples 1-3 are shown.
[0024] Figure 2 Scanning electron microscope images of CoFe PBA prepared in the examples and comparative examples 1-3.
[0025] Figure 3 Transmission electron microscope image of CoFe PBA prepared for the example.
[0026] Figure 4 The 2e of CoFe PBA prepared for Examples and Comparative Examples 1-3 – ORR linear scan voltammetry (a) and selectivity plot (b).
[0027] Figure 5 The H2O2 production rate (a) and Faraday efficiency (b) of CoFe PBA prepared in Examples 1-3 and Comparative Examples 1-3 at different current densities in a gas diffusion electrode device.
[0028] Figure 6 CoFe PBA prepared for this example was used in a gas diffusion electrode at -50 mA cm⁻¹ -2 The long-cycle H2O2 production rate, Faraday efficiency, and corresponding potential obtained under the given conditions. Detailed Implementation
[0029] A Prussian blue-like catalyst with highly exposed (111) crystal faces is prepared by dissolving soluble cobalt salt and sodium citrate dihydrate in water at a mass ratio of (1~3):(3~1) to prepare solution A; dissolving potassium ferricyanide in water to prepare solution B; and rapidly pouring solution B into solution A under stirring at a molar ratio of Co to Fe of (1~10):(10~1). After mixing evenly, the resulting mixture is transferred to a polytetrafluoroethylene liner and subjected to hydrothermal reaction at 0 ℃~140 ℃ for 12~24 h. The resulting product is ultrasonically cleaned three times with deionized water and ethanol, respectively. After centrifugation, the product is placed in a vacuum oven and dried at 60 ℃ for 12 h to obtain a Prussian blue-like catalyst with highly exposed (111) crystal faces.
[0030] The soluble cobalt salt is any one of cobalt nitrate, cobalt acetate, and cobalt chloride.
[0031] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto. Example
[0032] 0.1494 g of cobalt acetate (Co(CH3COO)2) and 0.2647 g of sodium citrate dihydrate (C6H5Na3O7·2H2O) were accurately weighed and completely dissolved in 20 mL of deionized water to obtain solution A; 0.1317 g of potassium ferricyanide (K3Fe(CN)6) was weighed and completely dissolved in 20 mL of deionized water to obtain solution B. Under continuous magnetic stirring, solution B was quickly poured into solution A, and stirring was continued for 30 min to obtain a suspension. The resulting suspension was then transferred to a polytetrafluoroethylene liner and hydrothermally heated at 90 °C for 24 h. After the reaction was completed, the product was collected by centrifugation, and the precipitate was repeatedly washed with deionized water and ethanol and centrifuged multiple times to remove impurities and unreacted substances. Finally, the washed precipitate was dried in a vacuum oven at 60 °C to obtain CoFe PBA with highly exposed (111) crystal faces (Co / Fe=2.11).
[0033] Comparative Example 1 The 90 ℃ hydrothermal bath was replaced with a 0 ℃ ice-water bath, and other operations were the same as in the previous example, resulting in a CoFe PBA with exposed (100) crystal planes.
[0034] Comparative Example 2 The hydrothermal temperature was changed from 90 °C to 40 °C, and other operations were the same as in the example, resulting in a CoFe PBA with low exposure of (111) crystal planes.
[0035] Comparative Example 3 The hydrothermal temperature was changed from 90 ℃ to 140 ℃, and other operations were the same as in the previous example, resulting in an irregular CoFePBA.
[0036] Figure 1 The XRD patterns of CoFe PBA prepared in the examples and comparative examples are shown in the figure. As can be seen from the figure, the synthesized CoFe PBA all showed diffraction peaks consistent with K2CoFe(CN)6 (PDF#75-0038) around 17.62°, 25.02°, 35.67° and 40.00°.
[0037] Figure 2 SEM images of CoFe PBA prepared in the examples and comparative examples are shown. As can be seen from the figures, CoFe PBA synthesized at a hydrothermal reaction temperature of 0℃ exhibits a perfect cubic structure, exposing the (100) crystal facet. With increasing hydrothermal reaction temperature, the (111) crystal facet gradually becomes exposed. When the hydrothermal reaction temperature rises to 90℃, the resulting CoFe PBA exhibits a truncated octahedral morphology, with the highest exposure of the (111) crystal facet. However, when the temperature continues to rise to 140℃, irregular dissolution occurs. The crystal facet exposure of each CoFe PBA sample is calculated and shown in Table 1.
[0038] Table 1. Crystal plane exposure of CoFe PBA obtained in the examples and comparative examples
[0039] As shown in Table 1, when the hydrothermal synthesis temperature is 90℃, the synthesized CoFe PBA achieves the highest exposure of the (111) crystal plane, with an exposure rate as high as 36.60% (the area and proportion of the exposed crystal plane of the Comparative Example 3 sample cannot be determined due to irregular dissolution).
[0040] Figure 3 The image shows a TEM image of the CoFe PBA prepared for the example. The image further demonstrates that the synthesized CoFe PBA has a truncated cubic structure, which exposes the (111) crystal plane.
[0041] The electrocatalytic performance of the prepared CoFePBA catalyst in the two-electron oxygen reduction reaction to produce hydrogen peroxide was investigated. The specific implementation steps are as follows: 1) Pretreatment of the rotating ring disk electrode: polish the 0.05 μm Al2O3 powder on the chamois to a mirror finish, then rinse it with deionized water to remove physically adsorbed particles, and then dry it with argon gas to obtain the initial electrode. 2) Preparation of working electrode: 10 mg of CoFe PBA catalyst and 35 μL of 5 wt% Nafion proton exchange membrane solution were ultrasonically mixed in 1 mL of isopropanol to form a slurry; under infrared lamp, 10 μL of the slurry was uniformly drop-coated onto the disk electrode of the pretreated ring-disk electrode to prepare the working electrode. 3) Assembly of the three-electrode system: The working electrode is the cathode, the Pt wire is the counter electrode, and the Ag / AgCl is the reference electrode. It is fixed in a three-electrode system with an F-type aeration tube. The volume of the electrolyte is about 100 mL.
[0042] 4) Under normal temperature and pressure conditions, the electrochemical performance of the assembled three-electrode system was tested using oxygen-saturated 0.1 M KOH solution as the electrolyte; during the reaction, the voltage on the disk electrode was 0.2 ~ 0.8 V. vs. RHE, the reaction voltage of the ring electrode is 1.5 V. vs. RHE, rotating at 1600 rpm; calculate the selectivity of H2O2 after the reaction is complete; 5) Under normal temperature and pressure conditions, using the assembled gas diffusion electrolysis cell, apply 20 μl of slurry with a pipette to a working area of 1 × 1 cm. 2 The working electrode is formed on hydrophobic carbon paper, creating a gas-solid-liquid three-phase system at the interface. A Pt sheet is used as the counter electrode, Ag / AgCl as the reference electrode, and 0.1 M KOH saturated with oxygen is used as the cathode electrolyte and 0.1 M KOH as the anolyte, separated by an anion exchange membrane. The system operates under constant current conditions (-10 ~ -90 mA cm⁻¹). 2 The reaction was carried out for 30 min, and then 100 μL of the electrolyte was taken and 1 mL of potassium iodide and 1 mL of potassium hydrogen phthalate were added for color development. The H2O2 production rate and Faraday efficiency were then detected using an Agilent high-performance liquid chromatograph. The performance test results are shown in Table 2.
[0043] Table 2. 2e of the catalysts obtained in the examples and comparative examples – ORR performance evaluation
[0044] As shown in Table 2, when the disk current density reaches -0.1 mA cm⁻¹ -2 At that time, the onset potential of the CoFe PBA with high exposure (111) crystal plane prepared in the example was 0.67 V. vs. RHE, compared to the comparative example, showed a higher onset potential, indicating higher ORR activity, and ultimately achieved 98.75% selectivity; simultaneously at -50 mA cm⁻¹ -2 It reached 7.72 mol g. cat. - 1 h -1 The H2O2 preparation rate and 100% Faraday efficiency were achieved. In contrast, the CoFe PBA with exposed (100) crystal planes in Comparative Example 1 showed only 12.32% selectivity and 1.11 mol g⁻¹.cat. -1 h -1 The H2O2 preparation rate and Faraday efficiency of 23.80% (e.g.) Figure 4 , 5 ).
[0045] The catalyst prepared in the example was used in the above-mentioned gas diffusion electrolyzer for a two-electron oxygen reduction reaction (reaction current was -50 mA cm⁻¹). -2 ), to determine its 2e - The long-term stability of ORR was demonstrated. Results showed that after 50 h of 2e-ORR performance testing, the catalyst still maintained a concentration of 7.72 mol g / L. cat. -1 h -1 The H2O2 production rate and 100% Faraday efficiency (e.g.) Figure 6 This indicates that the catalyst has the ability to efficiently and stably electrosynthesize H2O2.
[0046] In summary, this invention successfully prepared CoFe PBA with highly exposed (111) crystal faces by controlling the synthesis temperature using a simple hydrothermal method. This catalyst, with its unique crystal structure, optimizes the adsorption energy for reaction intermediates, thus achieving a balance of high activity, high selectivity, and high stability in the 2e⁻ORR electrosynthesis of H₂O₂. Its preparation method is simple and inexpensive, providing a new approach for the design and development of highly efficient electrocatalysts and demonstrating promising industrial application prospects.
[0047] The specific embodiments described above can further illustrate the purpose, technical solution and beneficial effects of the present invention. However, it should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A Prussian blue-like catalyst with high exposure of (111) crystal planes, characterized in that, Its (111) crystal plane exposure reaches more than 14%.
2. A method for preparing a Prussian blue-like catalyst with high exposure of (111) crystal planes as described in claim 1, characterized in that, Includes the following steps: 1) Dissolve soluble cobalt salt and sodium citrate dihydrate in water to prepare solution A; dissolve potassium ferricyanide in water to prepare solution B; under stirring conditions, quickly pour solution B into solution A, mix evenly, and then transfer the resulting mixture to a polytetrafluoroethylene liner for hydrothermal precipitation. 2) The product obtained in step 1) was ultrasonically cleaned three times with deionized water and ethanol, and then centrifuged, washed and dried to obtain the Prussian blue-like catalyst with high exposure of (111) crystal plane.
3. The preparation method according to claim 2, characterized in that, The soluble cobalt salt mentioned in step 1) is any one of cobalt nitrate, cobalt acetate, and cobalt chloride.
4. The preparation method according to claim 2, characterized in that, The mass ratio of the soluble cobalt salt to sodium citrate dihydrate used in step 1) is (1~3):(3~1).
5. The preparation method according to claim 2, characterized in that, Step 1) The molar ratio of Co to Fe in the mixture is (1~10):(10~1).
6. The preparation method according to claim 2, characterized in that, The temperature of the hydrothermal precipitation in step 1) is 0 ℃~140 ℃, and the time is 12~24 h.
7. The application of a Prussian blue-like catalyst with high exposure (111) crystal planes as described in claim 1 in the electrocatalytic two-electron oxygen reduction to prepare hydrogen peroxide.