Mn-cu s catalyst and method for hydrogen peroxide production

Abstract

A Mn-CuS catalyst and method for hydrogen peroxide production, the Mn-CuS (manganese-doped copper sulfide) can make Mn-CuS have excellent selectivity and high yield of H2O2 (hydrogen peroxide) in the electrochemical synthesis of H2O2, and the Mn-CuS catalyst shows very good cycle stability, Mn-CuS is expected to be widely used in energy production field due to the advantages of simple synthesis scheme, environmental friendliness, cost effectiveness and the like, and is also expected to be widely used in other 2e ‑ The design of the -ORR catalyst is inspiring.

Description

TECHNICAL FIELD

[0001] The present application relates to transition metal sulfide catalyst technology in hydrogen peroxide production, in particular a Mn-CuS catalyst and method for hydrogen peroxide production, which can make Mn-CuS have excellent selectivity and high yield of H2O2 (hydrogen peroxide) in the realization of electrochemical synthesis of H2O2, and the Mn-CuS catalyst exhibits very good cycle stability, and Mn-CuS is expected to be widely used in energy production field due to its advantages such as simple synthesis scheme, environmental friendliness, cost-effectiveness, etc., and can be used as a 2e - -ORR catalyst design is of great significance. BACKGROUND

[0002] Hydrogen peroxide (H2O2) is widely used as an environmentally friendly chemical oxidant in environmental treatment and chemical industry, including wastewater treatment, medical disinfection, papermaking and pulp bleaching, and organic / inorganic chemical synthesis. In addition, due to the high oxidation potential, easy transportation and storage, and clean water byproduct of H2O2, it can also be used as a sustainable energy carrier to replace oxygen (O2) and hydrogen (H2) in fuel cells. At present, the industrial production of H2O2 mainly adopts anthraquinone method. This method not only involves a large amount of energy and resource input, but also needs subsequent complex extraction, purification and transportation treatment. In addition, this method also produces a large amount of waste liquid. Therefore, this route is not an economic and environmentally friendly method. Another way is to directly synthesize H2O2 using a mixture of H2 and O2. However, this method is thermodynamically favorable for the production of water rather than H2O2, and usually requires the use of noble metal-based catalysts. In addition, the selectivity of H2O2 is poor and the yield is relatively low. Moreover, the mixture of raw materials H2 and O2 also has the potential risk of explosion. In order to solve the above problems, another direct and efficient method for producing H2O2 has emerged, which is based on the cathode-driven oxygen reduction reaction (ORR) and the anode-based water oxidation reaction (WOR) based on proton-coupled electron transfer (PCET). However, due to uphill thermodynamics and slow kinetics (1.76V), the electrochemical WOR itself is difficult to achieve, and the yield of H2O2 is extremely low. Therefore, most of the current research is mainly focused on the ORR reaction. Generally, the ORR at the cathode involves a multi-electron transfer process, in which O2 can be reduced to H2O through a four-electron pathway (4e - -ORR) or a two-electron pathway (2e - -ORR). In these two pathways, 4e - -ORR has been widely concerned, while 2e - -ORR electrochemical synthesis of H2O2 has become a new field. In recent years, direct electrochemical 2e --ORR for H2O2 production has attracted increasing attention. However4e - -ORR pathway is2e - -ORR pathway is a strong competing reaction for electrochemical synthesis of H2O2, significantly limiting the activity and selectivity of H2O2 production. Therefore, by electrochemical2e - -ORR for efficient production of H2O2 remains a major challenge. Developing catalysts with high catalytic activity, good selectivity, excellent stability, and cost-effectiveness, specifically for2e - -ORR pathway for H2O2 production has become an urgent problem.

[0003] In the early studies, most of the2e - -ORR pathway catalysts for H2O2 production were mainly made of expensive noble metal-based materials. Later, carbon-based materials also began to be used as2e - -ORR pathway catalysts. For carbon materials, carbon defect sites with structural diversity and electrochemical stability are crucial. For carbon-based materials, their tunable pore structure, intrinsic defects, good electrical conductivity, high surface area, and excellent stability make them very suitable for electrochemical2e - -ORR pathway in acid / alkaline electrolytes. Bao and colleagues developed porous carbon with different pore size ranges for electrochemical synthesis of H2O2 in alkaline media, which showed high selectivity for H2O2. In recent years, transition metal-based materials (mainly first-row elements such as Fe, Co, Ni, Cu, and Mn) have attracted much attention due to their excellent performance and have been developed as2e - -ORR pathway electrocatalysts. Certain types of metal oxides / sulfides also exhibit excellent performance in electrochemical H2O2 production. Li and colleagues synthesized a high-concentration single-atom Pt site catalyst, and the resulting Pt / CuSx catalyst achieved H2O2 production in 0.1 M HCIO4 with a selectivity of 92-96%, but the accumulation of H2O2 was not much. Yumauchi et al. found that nanoporous Mn-Ru oxides can also be used as a promising catalyst for electrochemical synthesis of H2O2 in 0.1 M KOH solution, which exhibits excellent long-term stability. Recently, Kim and colleagues developed a mesoporous C / Mn hybrid electrocatalyst (Mn-O / N@NCs) for electrochemical synthesis of H2O2. They found that the uniform distribution of Mn-Nx sites on nanocrystals (NCs) can promote2e -N-doped C without Mn can promote the 4e—ORR pathway, and the presence of Mn significantly inhibits the decomposition of H2O2. Therefore, proper surface functionalization of transition metal-based catalysts, including increasing the specific surface area and electrical conductivity, introducing defects and hierarchical porous structures, and metal atom doping, designing and forming single-atom catalysts with clear metal sites, etc. can achieve the electrochemical synthesis of H2O2. SUMMARY

[0004] The present application aims at the deficiencies in the prior art, and provides a Mn-CuS catalyst and method for hydrogen peroxide production. The Mn-CuS (manganese-doped copper sulfide) can enable the Mn-CuS to have excellent selectivity and high yield of H2O2 (hydrogen peroxide) in the electrochemical synthesis of H2O2, and the Mn-CuS catalyst exhibits very good cycle stability. The Mn-CuS is expected to be widely used in the field of energy production due to its advantages such as simple synthesis scheme, environmental friendliness, cost-effectiveness, etc. It is of great significance for the design of 2e - -ORR catalysts.

[0005] The technical solution of the present application is as follows:

[0006] A Mn-CuS catalyst for hydrogen peroxide production, characterized in that the content of each element in the Mn-CuS is Mn=11.8-25.69, Cu=43.97-33.35, and S=44.23-37.7 in wt%.

[0007] The Mn-CuS has a coral-like hierarchical porous nanosheet cluster microstructure.

[0008] A preparation method of a Mn-CuS catalyst for hydrogen peroxide production, characterized in that it comprises synthesizing Mn-CuS by one-pot hydrothermal reaction with copper chloride, manganese chloride, and thioacetamide (TAA) as raw materials.

[0009] The copper chloride is CuCl2·2H2O, the manganese chloride is MnCl2·4H2O, and the Mn-CuS has a coral-like hierarchical porous nanosheet cluster microstructure.

[0010] The synthesis of the Mn-CuS catalyst comprises the following steps:

[0011] Step 1, stirring and mixing CuCl2·2H2O, MnCl2·4H2O, ethylene glycol and deionized water into a first mixed solution;

[0012] Step 2, adding thioacetamide (TAA) to the first mixed solution under magnetic stirring to form a second mixed solution;

[0013] Step 3, the second mixed solution is heated in a stainless steel autoclave to synthesize Mn-CuS.

[0014] The molar ratio of MnCl2·4H2O and CuCl2·2H2O in step 1 is 1:0.5-4, and the volume ratio of ethylene glycol and deionized water is 2-4:1.

[0015] The molar ratio of MnCl2·4H2O and CuCl2·2H2O in step 1 is 1:2-3.5.

[0016] The molar ratio of CuCl2·2H2O and thioacetamide (TAA) in step 2 is 1:2.5-6.

[0017] The temperature in the stainless steel autoclave in step 3 is 180℃±10℃.

[0018] The content of each element in the Mn-CuS is 11.8-25.69wt%, Cu is 43.97-33.35wt%, and S is 44.23-37.7wt%.

[0019] The technical effects of the present application are as follows:(1) The raw materials of the present application are abundant, the preparation cost of the catalyst is low, and the preparation process is simple.(2) The present application develops a new type of bimetallic sulfide Mn-CuS catalyst through manganese doping strategy.(3) The present application not only changes the crystal structure of the atoms around the CuS catalyst, but also introduces a coral-like hierarchical porous structure, realizes a large increase in specific surface area and introduces a large number of lattice defects, so that the 2e – -ORR path is superior to the 4e – -ORR path, realizes the 2e – -ORR path has high selectivity for H2O2 production.(4) The present application synthesizes Mn-CuS-x composite materials containing different Mn contents by controlling the molar ratio of Mn to Cu, and finds that when Mn:Cu=1:3, the obtained composite material shows the most excellent performance for producing hydrogen peroxide, and the hydrogen peroxide concentration is as high as 24.5mM at 0.6V (relative to RHE) in 3 hours. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a scanning electron microscope (SEM) image of the CuS and Mn-CuS morphology involved in the preparation method of the Mn-CuS catalyst for hydrogen peroxide production of the present application. Figure 1The a, b, c, d, e, f figures contained in the middle are the morphologies of CuS, Mn-CuS-1, Mn-CuS-2, Mn-CuS-3, Mn-CuS-4, Mn-CuS-5, respectively. In wt%, Cu = 49.36, S = 50.64 in CuS; Mn = 11.8, Cu = 43.97, S = 44.23 in Mn-CuS-1; Mn = 12.56, Cu = 43.19, S = 44.25 in Mn-CuS-2; Mn = 13.27, Cu = 43.92, S = 42.82 in Mn-CuS-3; Mn = 14.17, Cu = 41.13, S = 44.17 in Mn-CuS-4; Mn = 25.69, Cu = 33.35, S = 37.7 in Mn-CuS-5.

[0021] Figure 2 is a performance parameter chart of CuS and Mn-CuS. Figure 2 in Figure 2 a is the comparison of ORR performance (solid line) and simultaneous hydrogen peroxide detection current on a ring electrode (dashed line) of CuS and Mn-CuS catalysts at 1,600 rpm, at 10 mV s -1 Scan disc potential, ring potential constant at 1.5V vs. RHE, where RHE is a reversible hydrogen electrode (N = 37.3%); Figure 2 b is the hydrogen peroxide selectivity at different potentials calculated from RRDE data, where RRDE is a rotating ring disk electrode. Figure 2 c is the comparison of hydrogen peroxide current (0.5V) of CuS and Mn-CuS; Figure 2 d is the EIS of CuS and all prepared Mn-CuS samples, where EIS is electrochemical impedance spectroscopy. Figure 2 e is the polarization curve of Mn-CuS-2 before and after 500 LSVs cycle durability test, where LSVs is linear sweep voltammetry. Figure 2 The inset in e represents the selectivity of the catalyst.

[0022] Figure 3 is a production device and test chart. Figure 3 in Figure 3 a is a schematic diagram of an electrochemical device for electrochemical production of hydrogen peroxide; Figure 3 b is a schematic diagram of the amount of hydrogen peroxide produced and reaction time when the cell output voltage is 0.6V; Figure 3c is a schematic diagram of the chronoamperometry stability test (0.6 V, 0.1 M KOH) of Mn-CuS-2. DETAILED DESCRIPTION

[0023] The application will be described below with reference to the accompanying drawings Figures 1-3 ) and examples.

[0024] Figure 1 is a SEM diagram of the morphology of CuS and Mn-CuS involved in a preparation method of Mn-CuS catalyst for hydrogen peroxide production. Figure 2 is a performance parameter diagram of CuS and Mn-CuS. Figure 3 is a production device and test diagram. Referring to Figures 1 to 3 , a Mn-CuS catalyst for hydrogen peroxide production is characterized in that the content of each element in the Mn-CuS is Mn = 11.8-25.69, Cu = 43.97-33.35, and S = 44.23-37.7 in wt%. The Mn-CuS has a coral-like hierarchical porous nanosheet cluster microstructure. A preparation method of Mn-CuS catalyst for hydrogen peroxide production comprises synthesizing Mn-CuS by one-pot hydrothermal reaction with copper chloride, manganese chloride, and thioacetamide (TAA) as raw materials. The copper chloride is CuCl2·2H2O, the manganese chloride is MnCl2·4H2O, and the Mn-CuS has a coral-like hierarchical porous nanosheet cluster microstructure.

[0025] The synthesis of Mn-CuS catalyst comprises the following steps: Step 1, stirring and mixing CuCl2·2H2O, MnCl2·4H2O, ethylene glycol, and deionized water into a first mixed solution; Step 2, adding thioacetamide (TAA) into the first mixed solution under magnetic stirring to form a second mixed solution; Step 3, heating and reacting the second mixed solution in a stainless steel autoclave to synthesize Mn-CuS. In Step 1, the molar ratio of MnCl2·4H2O to CuCl2·2H2O is 1:0.5-4, and the volume ratio of ethylene glycol to deionized water is 2-4:1. In Step 1, the molar ratio of MnCl2·4H2O to CuCl2·2H2O is 1:2-3.5. In Step 2, the molar ratio of CuCl2·2H2O to thioacetamide (TAA) is 1:2.5-6. In Step 3, the temperature in the stainless steel autoclave is 180℃±10%. In the Mn-CuS, the content of each element is Mn = 11.8-25.69, Cu = 43.97-33.35, and S = 44.23-37.7 in wt%.

[0026] The application designs a non-noble transition metal sulfide Mn-CuS catalyst by using a one-pot hydrothermal method, the catalyst has a hierarchical porous structure and defects derived from Mn doping. The obtained Mn-CuS realizes excellent selectivity and high yield of H2O2, and the catalyst shows very good cycle stability. Mn-CuS is expected to be engaged in some energy science activities due to the advantages of simple synthesis scheme, environmental friendliness, cost-effectiveness and the like, and can realize 2e – The design of the -ORR catalyst is inspiring.

[0027] A preparation method of a non-noble transition metal sulfide Mn-CuS catalyst, comprising the following steps:

[0028] Step A, CuCl2·2H2O and MnCl2·4H2O are added to a mixture of ethylene glycol and deionized water and stirred;

[0029] Step B, thioacetamide (TAA) is added to the above mixture under magnetic stirring;

[0030] Step C, the solution obtained in step B is transferred to a stainless steel autoclave for heating reaction to prepare a Mn-CuS catalyst material.

[0031] The features of the application include: (1) a new type of Mn-CuS composite nanosheet cluster; (2) a one-pot hydrothermal method is used to prepare a coral-like Mn-CuS composite nanosheet cluster; (3) an optimized ratio of Mn:Cu=1:3; (4) the concentration of H2O2 is as high as 24.5mM at 0.6V (relative to RHE) within 3 hours.

[0032] The application discloses a non-noble metal catalyst Mn-CuS-x which can be used for efficiently preparing hydrogen peroxide. The application has the characteristics that a transition metal sulfide catalyst Mn-CuS-x is synthesized through a one-pot hydrothermal reaction, and the coral-like hierarchical porous structure generated thereby not only has a high specific surface area, but also introduces a large number of defects. Through strategic structural design, the electrocatalyst makes the 2e - path superior to the 4e - path in kinetics. The 2e - path leads to high selectivity for hydrogen peroxide production, and the concentration of hydrogen peroxide is as high as 24.5mM at 0.6V (relative to RHE) within 3 hours. Among all the Mn-CuS-x catalysts, the Mn-CuS-2 catalyst shows very good stability, which shows that Mn-CuS can realize high stability and significant improvement of hydrogen peroxide production at the same time. The research provides a green, low-cost and efficient way for producing hydrogen peroxide, and is very promising for future applications in chemical and liquid fuel production.

[0033] Table S1. Formulations of Mn-CuS-x Samples

[0034] Table S1. Formulations of Mn-CuS-x Samples

[0035] sample MnCl2-4H2O (mmol) [CuCl2·2H2O (mmol)] TAA (mmol) CuS 0 1.5 3 Mn-CuS-1 0.5 2 5 Mn-CuS-2 0.5 1.5 4 Mn-CuS-3 0.5 1 3 Mn-CuS-4 1 1 4 Mn-CuS-5 1 0.5 3 MnS 1.5 0 3

[0036] Table S2. ICP measurement of atom content(Cu, Mn and S) of Mn-CuS-x samples.

[0037] Table S2. ICP measurement of atom content(Cu, Mn and S) of Mn-CuS-x samples.

[0038] sample M% Mn ]] Mn-CuS-1 11.09％ Mn-CuS-2 12.88％ Mn-CuS-3 14.81％ Mn-CuS-4 15.23％ Mn-CuS-5 46.76％

[0039] Table S3. Elemental compositions of CuS and Mn-CuS with different manganese dopant contents.

[0040] Table S3. Elemental compositions of CuS and Mn-CuS with different manganese dopant contents.

[0041] CuS Mn-CuS-1 Mn-CuS-2 Mn-CuS-3 Mn-CuS-4 Mn-CuS-5 Mn 0 11.8 12.56 13.27 14.17 25.69 Cu 49.36 43.97 43.19 43.92 41.13 33.35 S 50.64 44.23 44.25 42.82 44.17 37.7

[0042] Example 1: Coral-like Mn-CuS composite nanosheet clusters were prepared by a one-pot hydrothermal method. In a typical procedure, CuCl2-2H2O and MnCl2-4H2O (molar ratio of 2:1) were first added into a mixture of ethylene glycol and deionized water (volume ratio of 3:1) with stirring for 20 min. Subsequently, thioacetamide (TAA) was added into the solution under magnetic stirring for 20 min. The solution was then transferred into a 100 mL stainless steel autoclave and heated at 180 °C for 3 h.

[0043] Catalyst ink was prepared by dispersing 0.5 mg of catalyst in a solution containing 0.99 mL of deionized water and 10 μL of 5 wt% Nafion and sonicating for 10 min. Then 4.95 μL of catalyst ink was cast on the glassy carbon (GC) electrode portion surface of a rotating ring-disk electrode (RRDE) and dried to form a uniform thin film, where the loading of the electrode was 10 μg cm -2 . Measurements were performed using 0.1 M KOH aqueous solution saturated with O2 as the electrolyte, and the working electrode was rotated at a speed of 1,600 rpm, unless otherwise stated.

[0044] Example 2: Coral-like Mn-CuS composite nanosheet clusters were prepared by one-pot hydrothermal method. In a typical procedure, CuCl2-2H2O and MnCl2-4H2O (molar ratio of 1 : 1) were first added into a mixture of ethylene glycol and deionized water (volume ratio of 3: 1) with stirring for 20 min. Subsequently, thioacetamide (TAA) was added into the solution under magnetic stirring for 20 min. The solution was then transferred into a 100 mL stainless steel autoclave and heated at 180 °C for 3 h.

[0045] Catalyst ink was prepared by dispersing 0.5 mg of catalyst in a solution containing 0.99 mL of deionized water and 10 pL of 5 wt% Nafion and sonicating for 10 min. 4.95 pL of catalyst ink was then cast on the glassy carbon (GC) electrode portion surface of a rotating ring-disk electrode (RRDE) and dried to form a uniform thin film, with a loading of 10 pg cm -2 . Measurements were performed using 0.1 M KOH aqueous solution saturated with O2 as electrolyte, with a working electrode rotating at 1,600 rpm, unless otherwise stated.

[0046] Example 3: Coral-like Mn-CuS composite nanosheet clusters were prepared by one-pot hydrothermal method. In a typical procedure, CuCl2-2H2O and MnCl2-4H2O (molar ratio of 1 : 2) were first added into a mixture of ethylene glycol and deionized water (volume ratio of 3: 1) with stirring for 20 min. Subsequently, thioacetamide (TAA) was added into the solution under magnetic stirring for 20 min. The solution was then transferred into a 100 mL stainless steel autoclave and heated at 180 °C for 3 h.

[0047] Catalyst ink was prepared by dispersing 0.5 mg of catalyst in a solution containing 0.99 mL of deionized water and 10 pL of 5 wt% Nafion and sonicating for 10 min. 4.95 pL of catalyst ink was then cast on the glassy carbon (GC) electrode portion surface of a rotating ring-disk electrode (RRDE) and dried to form a uniform thin film, with a loading of 10 pg cm -2 . Measurements were performed using 0.1 M KOH aqueous solution saturated with O2 as electrolyte, with a working electrode rotating at 1,600 rpm, unless otherwise stated.

[0048] Example 4: Coral-like Mn-CuS composite nanosheet clusters were prepared by one-pot hydrothermal method. In a typical procedure, CuCl2-2H2O and MnCl2-4H2O (molar ratio of 1 :3) were first added into a mixture of ethylene glycol and deionized water (volume ratio of 3:1) with stirring for 20 min. Subsequently, thioacetamide (TAA) was added into the solution under magnetic stirring for 20 min. The solution was then transferred into a 100 mL stainless steel autoclave and heated at 180 °C for 3 h.

[0049] Catalyst ink was prepared by dispersing 0.5 mg of catalyst in a solution containing 0.99 mL of deionized water and 10 μL of 5 wt% Nafion and sonicating for 10 min. Then 4.95 μL of catalyst ink was cast on the glassy carbon (GC) electrode portion surface of a rotating ring-disk electrode (RRDE) and dried to form a uniform thin film, with a loading of 10 μg cm -2 on the electrode. Measurements were performed using 0.1 M KOH aqueous solution saturated with O2 as the electrolyte, with the working electrode rotating at 1,600 rpm, unless otherwise stated.

[0050] Example 5: Coral-like Mn-CuS composite nanosheet clusters were prepared by one-pot hydrothermal method. In a typical procedure, CuCl2-2H2O and MnCl2-4H2O (molar ratio of 1 :4) were first added into a mixture of ethylene glycol and deionized water (volume ratio of 3:1) with stirring for 20 min. Subsequently, thioacetamide (TAA) was added into the solution under magnetic stirring for 20 min. The solution was then transferred into a 100 mL stainless steel autoclave and heated at 180 °C for 3 h.

[0051] Catalyst ink was prepared by dispersing 0.5 mg of catalyst in a solution containing 0.99 mL of deionized water and 10 μL of 5 wt% Nafion and sonicating for 10 min. Then 4.95 μL of catalyst ink was cast on the glassy carbon (GC) electrode portion surface of a rotating ring-disk electrode (RRDE) and dried to form a uniform thin film, with a loading of 10 μg cm -2 on the electrode. Measurements were performed using 0.1 M KOH aqueous solution saturated with O2 as the electrolyte, with the working electrode rotating at 1,600 rpm, unless otherwise stated.

[0052] Experimental materials and methods: CuCl2 2H2O, MnCl2 4H2O, thioacetamide, KOH, HC1, HCIO4 and ethylene glycol were purchased from National Pharmaceutical Group Chemical Reagent Co., Ltd. (China) and used as received. Cerium sulfate (Ce(SO4)2, purity 99.9%) was provided by Araldin Co., Ltd. (Shanghai). The coral-like Mn-CuS composite nanosheet clusters were prepared by a one-pot hydrothermal method. In a typical procedure, CuCl2 2H2O and MnCl2 4H2O were first added into a mixture of ethylene glycol and deionized water (volume ratio 3:1) with stirring for 20 min. To investigate the effect of Mn content on the structure and performance of the final Mn-CuS catalyst, Mn-CuS-x composites containing different Mn contents were synthesized by using the same method with controlled molar ratios of Mn to Cu. Subsequently, thioacetamide (TAA) was added into the solution under magnetic stirring for 20 min. Then the solution was transferred into a 100 mL stainless steel autoclave and heated at 180 °C for 3 h.

[0053] Catalytic characterization: The morphology of the samples was characterized by using a field emission scanning electron microscope (FESEM) (S4800, Hitachi) at an operating voltage of 20.0 kV and a field emission transmission electron microscope (FETEM) (JEM 2010, JEOL, Japan) operating at 200 kV. Electron paramagnetic resonance (EPR) spectroscopy experiments were performed using a Bruker EMX-plus-10 / 12 instrument. The specific surface area and porosity of the samples were characterized using an automatic volumetric adsorption analyzer (Quantachrome, Autosorb-IQ-MP). The phase analysis and crystal structure of the synthesized materials were characterized using a Bruker D8 Advance X-ray powder diffractometer using Cu Ka radiation (l = 1.5406 nm) and operating at a voltage of 40 kV, a current of 30 mA, a 2Q angle range between 5° and 85° with a scan rate of 2° min -1 The elemental composition of the samples was determined by X-ray photoelectron spectroscopy (XPS) using a VG ESCALAB 250 spectrometer (Thermo Electron, UK) with an Al Ka X-ray source (1486 eV). Raman spectra were collected using an XploRA PLUS (HORIBA, France) and inductively coupled plasma atomic emission spectrometer (ICP-AES) measurements were performed using an Optima 7300DV.

[0054] Electrochemical measurements: Rotating ring-disk electrode (RRDE) tests. The electrochemical performance of selective ORR was evaluated in a standard three-electrode system controlled by a potentiostat (CHI760C, CH Instrument, USA) equipped with a RRDE apparatus. A Pt sheet and a saturated calomel electrode (SCE) were used as the counter and reference electrodes, respectively. A pre-polished glassy carbon (GC) disk with a Pt ring electrode (E7R9; Pine Instrument Company; 0.2475 cm 2 disk area and 0.1866 cm 2 ring area; 0.37 theoretical collection efficiency) was used as the working electrode.

[0055] Catalyst ink was prepared by dispersing 0.5 mg of catalyst in a solution containing 0.99 mL of deionized water and 10 pL of 5 wt% Nafion and sonicating for 10 min. Then 4.95 pL of catalyst ink was cast on the GC portion surface of the RRDE and dried to form a uniform thin film, where the loading of the electrode was 10 pg cm -2 -2. Unless otherwise stated, measurements were performed using 0.1 M KOH aqueous solution saturated with O2as the electrolyte, and the working electrode was rotated at a speed of 1,600 rpm.

[0056] Electrochemical direct synthesis of H2O2: The electrochemical ORR was performed in a custom-made H-type electrolytic cell with a Nafion membrane as the separator to quantify the amount of H2O2(FIG. S2, ESI). The two-port chamber of the cell was filled with 50 mL of O2-saturated electrolyte and 10 mM ethylenediaminetetraacetic acid (EDTA). EDTA can be used as an inhibitor for the decomposition of H2O2. To remove surface oxides, carbon paper was pretreated with 6 M HC1 before being used as the current collector to test the electrochemical performance and stability of the prepared electrode materials during the H2O2 generation process. The cathode was prepared by depositing Mn-CuS catalyst ink on carbon paper with a size of 2 cm x 2 cm (2 mg cm -2 -2). The electrolyte in the cathode chamber was purged with pure O2gas and stirred with a magnetic stirrer to ensure that the reactant could reach the electrode surface. The electrolyte in the cathode chamber was constantly purged with oxygen and stirred with a magnetic stirrer to ensure that oxygen could reach the electrode surface. In practice, the device is usually operated at a constant current or potential. Therefore, we controlled the constant potential for H2O2 production and catalyst durability testing at -0.65 V (vs. SCE).

[0057] H2O2 concentration measurement: The H2O2 concentration can be determined by the traditional cerium sulfate Ce(SO4)2 titration method.

[0058] The content not described in detail in the specification of the present application belongs to the prior art known to the person skilled in the art. It is indicated here that the above description helps the person skilled in the art to understand the present application, but does not limit the protection scope of the present application. Any implementation of equivalent replacement, modification, improvement and / or deletion of the above description without departing from the essential content of the present application falls within the protection scope of the present application.

Claims

1. A Mn-CuS catalyst for the production of hydrogen peroxide, used in the electrochemical synthesis of H2O2, characterized in that, The elemental contents in Mn-CuS, expressed in wt%, are Mn = 11.8–25.69, Cu = 43.97–33.35, and S = 44.23–37.

7.

2. The Mn-CuS catalyst for hydrogen peroxide production according to claim 1, characterized in that, The Mn-CuS exhibits a coral-like hierarchical porous nanosheet cluster microstructure.

3. A method for preparing a Mn-CuS catalyst for hydrogen peroxide production, wherein the Mn-CuS catalyst is used for the electrochemical synthesis of H2O2, characterized in that... This includes the synthesis of Mn-CuS via a one-pot hydrothermal reaction using copper chloride, manganese chloride, and thioacetamide (TAA) as raw materials; The content of each element in the Mn-CuS is calculated in wt%, with Mn = 11.8–25.69, Cu = 43.97–33.35, and S = 44.23–37.

7.

4. The method for preparing the Mn-CuS catalyst for hydrogen peroxide production according to claim 3, characterized in that, The copper chloride is CuCl2·2H2O, the manganese chloride is MnCl2·4H2O, and the Mn-CuS has a coral-like hierarchical porous nanosheet cluster microstructure.

5. The method for preparing the Mn-CuS catalyst for hydrogen peroxide production according to claim 3, characterized in that, The synthesis of Mn-CuS catalysts includes the following steps: Step 1: Mix CuCl2·2H2O, MnCl2·4H2O, ethylene glycol and deionized water to form a first mixture. Step 2: Add thioacetamide (TAA) to the first mixture under magnetic stirring to form the second mixture; Step 3: The second mixture is heated in a stainless steel autoclave to synthesize Mn-CuS.

6. The method for preparing the Mn-CuS catalyst for hydrogen peroxide production according to claim 5, characterized in that, In step 1, the molar ratio of MnCl2·4H2O and CuCl2·2H2O is 1:0.5-4, and the volume ratio of ethylene glycol and deionized water is 2-4:

1.

7. The method for preparing the Mn-CuS catalyst for hydrogen peroxide production according to claim 5, characterized in that, In step 1, the molar ratio of MnCl2·4H2O and CuCl2·2H2O is 1:2 to 3.

5.

8. The method for preparing the Mn-CuS catalyst for hydrogen peroxide production according to claim 5, characterized in that, In step 2, the molar ratio of CuCl2·2H2O to thioacetamide (TAA) is 1:2.5–6.

9. The method for preparing the Mn-CuS catalyst for hydrogen peroxide production according to claim 5, characterized in that, In step 3, the temperature in the stainless steel autoclave is 180℃±10℃.

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