Method for electrocatalytic efficient synthesis of formaldehyde from carbon monoxide

Abstract

The application provides a method for efficiently synthesizing formaldehyde by electrocatalysis of carbon monoxide, and the core is: first, a phthalocyanine cobalt molecular material is used as an electrocatalyst for selectively preparing formaldehyde, the material has a clear C1 selective formaldehyde generation path, and can essentially inhibit the undesired C-C coupling of intermediates; second, the reaction is carried out under high carbon monoxide pressure to enhance the competitive adsorption effect of carbon monoxide. The application proposes a carbon monoxide competitive adsorption strategy, which combines the intrinsic substituent regulation of phthalocyanine cobalt molecular materials and external carbon monoxide pressurization to inhibit the over-reduction of formaldehyde, detach the formaldehyde intermediate from the active site, and realize the selective electro-synthesis. The CoPc-OMe MDE optimized by the application realizes 98% CO-to-HCHO selectivity under 90 bar carbon monoxide, the peak Faraday efficiency is 72%, and the formaldehyde partial current density is more than 110 mA·cm ‑2 .

Description

Technical Field

[0001] This invention relates to the field of electrocatalysis, specifically to a method for the efficient synthesis of formaldehyde from carbon monoxide via electrocatalysis. Background Technology

[0002] Formaldehyde (HCHO) is a key C1 platform molecule with a global annual production capacity exceeding 52 million tons. It plays an indispensable role in petrochemicals, pharmaceuticals, and agriculture, and is also considered a core chemical intermediate for the sustainable production of carbohydrates. Traditional industrial synthesis of formaldehyde relies on a multi-step redox tandem reaction: first, carbon monoxide (CO) is catalytically hydrogenated to methanol (200-300℃, 50-100 bar), followed by the partial oxidation / dehydrogenation of methanol (300-400℃) to produce formaldehyde. This indirect synthesis route requires energy-intensive combustion and purification processes, and is accompanied by emissions of carbon dioxide and volatile organic compounds (VOCs). Notably, approximately 35% of global methanol production is used for formaldehyde production. For a long time, direct CO2 / CO conversion to formaldehyde has been considered a more energy-efficient alternative. In a recent study of ruthenium-based catalytic systems, researchers achieved selectivity >65% under moderate pressure conditions (10 bar CO2, 10 bar H2), but the yield remained low (0.00048 mol·g⁻¹) due to thermodynamic limitations. 催化剂 -1 ·h -1 ).

[0003] In existing technologies, electrocatalytic CO2 / CO reduction reactions coupled with renewable energy provide a sustainable alternative pathway for the green synthesis of chemicals. Currently, the most advanced electrochemical systems have achieved Faradaic efficiencies (FE) >50% and partial current densities (j) for stable C1-C3 products (such as CH4, CH3OH, C2H4). C1-C3 >100 mA·cm -2 However, formaldehyde is rarely reported as a major product. In copper-based catalysts that dominate CO2 / CO deep reduction systems, formaldehyde intermediates were not detected because intermediate species (CO or HCHO) on the copper (Cu) surface inherently tend to undergo rapid CC coupling. Existing research indicates that molecularly dispersed cobalt phthalocyanine electrocatalysts uniquely mediate the C1-selective conversion pathway from CO2 to CH3OH via formaldehyde intermediates, achieving a formaldehyde Faradaic efficiency (FE) of 17% after optimization (including lowering the operating temperature and using CO as a feedstock). HCHO ).

[0004] However, the partial current density of formaldehyde (j HCHO It is still two orders of magnitude lower than that of methanol (<0.65 mA·cm⁻¹). -2This indicates that formaldehyde readily undergoes rapid hydrogenation under reducing conditions. To achieve selective electrosynthesis of formaldehyde, strategies to suppress excessive reduction are needed, but related research remains limited.

[0005] In conclusion, a new technical solution is urgently needed to address the problems existing in the current technology. Summary of the Invention

[0006] This invention provides a method for the efficient electrocatalytic synthesis of formaldehyde from carbon monoxide. The invention proposes a competitive adsorption strategy for carbon monoxide, combining intrinsic substituent regulation of cobalt phthalocyanine molecular materials with external carbon monoxide pressurization to suppress excessive reduction of formaldehyde, desorbing the formaldehyde intermediate from the active site and achieving its selective electrosynthesis. The CoPc-OMe MDE optimized by this invention achieves 98% CO-to-HCHO selectivity at 90 bar of carbon monoxide, with a peak Faraday efficiency of 72% and a formaldehyde fractional current density exceeding 110 mA·cm⁻¹. -2 .

[0007] One object of the present invention is to provide a method for the efficient electrocatalytic synthesis of formaldehyde from carbon monoxide, comprising the following steps: S1. Carbon nanotubes and cobalt phthalocyanine molecular materials are dispersed in solvent 1 to obtain carbon nanotube suspension and cobalt phthalocyanine molecular material suspension respectively; the carbon nanotube suspension and cobalt phthalocyanine molecular material suspension are blended, ultrasonically treated, and stirred to obtain crude product; the crude product is purified and dried to obtain cobalt phthalocyanine-based molecularly dispersed electrocatalyst. S2. The cobalt phthalocyanine-based molecularly dispersed electrocatalyst and the ionic polymer are dispersed in solvent 2 and then coated onto carbon paper to obtain a cobalt phthalocyanine-based molecularly dispersed electrocatalyst electrode. S3. The phthalocyanine cobalt-based molecularly dispersed electrocatalyst electrode is installed in an electrolytic cell, and carbon monoxide is introduced to carry out an electrocatalytic reaction to obtain formaldehyde; in, The gas pressure of the carbon monoxide is 5-120 bar.

[0008] Further, in step S1, the cobalt phthalocyanine molecular material is selected from one or more of cobalt phthalocyanine or cobalt phthalocyanine derivatives.

[0009] Furthermore, the cobalt phthalocyanine derivative includes electron-withdrawing cobalt phthalocyanine and electron-donating cobalt phthalocyanine.

[0010] Further, the electron-withdrawing group of the electron-withdrawing cobalt phthalocyanine is selected from one or more of cyano, -Cl, -F or -NO2; the electron-donating group of the electron-donating cobalt phthalocyanine is selected from one or more of methoxy, -OH, -NH2 or -Me; the electron-withdrawing cobalt phthalocyanine is preferably cyano-substituted cobalt phthalocyanine; the electron-donating cobalt phthalocyanine is preferably methoxy-substituted cobalt phthalocyanine.

[0011] Further, in step S1, the mass ratio of the carbon nanotubes to the cobalt phthalocyanine molecular material is (6-100):1.

[0012] Further, in step S2, the mass ratio of the cobalt phthalocyanine-based molecularly dispersed electrocatalyst to the ionic polymer is 1:(0.01-1).

[0013] Further, in step S1, the solvent 1 is selected from one or more of N,N-dimethylformamide or dimethyl sulfoxide.

[0014] Further, in step S2, the solvent 2 is selected from one or more of methanol or ethanol.

[0015] Furthermore, in step S2, the amount of cobalt phthalocyanine-based molecularly dispersed electrocatalyst supported on the carbon paper is 0.1-2 mg·cm⁻¹. -2 .

[0016] The present invention has the following beneficial effects: This invention provides a method for the efficient electrocatalytic synthesis of formaldehyde from carbon monoxide. The core of this method lies in two aspects: First, using cobalt phthalocyanine as an electrocatalyst for the selective preparation of formaldehyde. This type of material exhibits a clear C1-selective formaldehyde generation pathway, which can essentially suppress undesirable C-C coupling of intermediates. Second, conducting the reaction under high carbon monoxide pressure conditions to enhance the competitive adsorption effect of carbon monoxide. Since the adsorption strength of carbon monoxide on cobalt phthalocyanine is significantly higher than that on formaldehyde, competitive adsorption can effectively prevent excessive reduction of formaldehyde. Simultaneously, by optimizing the molecular structure of cobalt phthalocyanine, the adsorption advantage of carbon monoxide relative to formaldehyde can be further enhanced. Given that the low solubility of carbon monoxide (0.95 mM) under standard conditions may limit the competitive adsorption kinetics, this invention further proposes a technical solution using even higher carbon monoxide pressure. By combining intrinsic substituent regulation with external carbon monoxide pressurization, the competitive adsorption of CO-HCHO is strategically enhanced to improve the selectivity of formaldehyde in the carbon monoxide electroreduction reaction, ultimately achieving efficient desorption of formaldehyde intermediates from active sites and selective electrosynthesis. The CoPc-OMe MDE optimized by this invention achieves excellent technical performance under carbon monoxide pressures of 5-120 bar, especially achieving 98% CO-to-HCHO selectivity at 90 bar carbon monoxide pressure, with a peak Faraday efficiency of 72% and a formaldehyde fractional current density exceeding 110 mA·cm⁻¹.-2 . Attached Figure Description

[0017] Figure 1 The diagram shows different formaldehyde production routes and a comparison of the Faraday efficiency and local current density for the electrocatalytic preparation of different products. in, Figure 1 (a) shows a schematic diagram of different formaldehyde production routes; Figure 1 (b) shows a comparison of the Faraday efficiency for the electrocatalytic preparation of different products; Figure 1 (c) shows a comparison of local current densities for different products.

[0018] Figure 2 The C1 conversion pathway of CO2 reduction on a cobalt phthalocyanine-based molecularly dispersed electrocatalyst and the high-angle annular dark-field scanning transmission electron microscope image of the CoPc-OMe MDE are shown. in, Figure 2 (a) illustrates the C1 conversion pathway of CO2 reduction on a cobalt phthalocyanine-based molecularly dispersed electrocatalyst; Figure 2 (b) shows a high-angle annular dark-field scanning transmission electron microscope image of the CoPc-OMe MDE.

[0019] Figure 3 The intrinsic substituent regulation of CoPc and the comparison of its calculated adsorption energies for carbon monoxide and formaldehyde are shown. in, Figure 3 (a) illustrates the intrinsic substituent regulation of CoPc; Figure 3 (b) shows a comparison of the calculated adsorption energies of CoPc, CoPc-CN, and CoPc-OMe for carbon monoxide and formaldehyde.

[0020] Figure 4 The diagrams show the direct electroreduction of formaldehyde under normal pressure and the inhibitory effect of formaldehyde electroreduction under high pressure CO conditions. in, Figure 4 (a) shows a schematic diagram of the direct electroreduction of formaldehyde under normal pressure; Figure 4 (b) shows a schematic diagram of the inhibitory effect of formaldehyde electroreduction under high pressure CO conditions.

[0021] Figure 5The LSV curves of formaldehyde electroreduction catalyzed by three cobalt phthalocyanine-based molecularly dispersed electrocatalysts and the LSV curves of formaldehyde electroreduction catalyzed by CoPc-OMe MDE under different carbon monoxide pressures are shown. in, Figure 5 (a) shows the LSV curves of formaldehyde electroreduction catalyzed by three cobalt phthalocyanine-based molecularly dispersed electrocatalysts; Figure 5 (b) shows the LSV curves of formaldehyde electroreduction catalyzed by CoPc-OMe MDE under different carbon monoxide pressures.

[0022] Figure 6 A schematic diagram illustrating the inhibition of further reduction of formaldehyde by high-pressure carbon monoxide competitive adsorption is shown.

[0023] Figure 7 The electrolyte sample is shown. 13 C NMR and 1 The magnified area of ​​the H NMR spectrum, as well as the UV-Vis spectrum used for colorimetric quantification of formaldehyde and photographs of the solution before and after the reaction; in, Figure 7 (a) shows the electrolyte sample. 13 C NMR and 1 Magnified region of H NMR spectrum; Figure 7 (b) shows the UV-Vis spectrum used for colorimetric quantification of formaldehyde and photographs of the solution before and after the reaction.

[0024] Figure 8 The total current density is shown to be -10 mA·cm. -2 At the same time, FE and j under different carbon monoxide applied pressures HCHO And under a carbon monoxide pressure of 90 bar, the FE and j corresponding to different applied potentials HCHO ; in, Figure 8 (a) shows a total current density of -10 mA·cm -2 At the same time, FE and j under different carbon monoxide applied pressures HCHO ; Figure 8 (b) shows the FE and j corresponding to different applied potentials under a carbon monoxide pressure of 90 bar. HCHO .

[0025] Figure 9 The selectivity of formaldehyde production from carbon monoxide via electrocatalysis is shown to vary with carbon monoxide pressure and potential.

[0026] Figure 10The long-cycle electrocatalytic performance of the cobalt phthalocyanine-based molecularly dispersed electrocatalyst is demonstrated. in, Figure 10 (a) shows the liquid-phase product Faraday efficiency and the change in applied potential of a methoxy-substituted cobalt phthalocyanine molecularly dispersed electrocatalyst for the electroreduction of carbon monoxide; Figure 10 (b) shows the corresponding performance data for the cobalt phthalocyanine molecularly dispersed electrocatalyst; Figure 10 (c) shows the corresponding performance data of the cyano-substituted cobalt phthalocyanine molecularly dispersed electrocatalyst; Figure 10 (d) shows the cyclic voltammetry curves before and after the electrocatalytic reaction of the CoPc-OMe MDE molecularly dispersed electrocatalyst; Figure 10 (e) shows the cyclic voltammetry curves of the CoPc MDE molecularly dispersed electrocatalyst before and after the electrocatalytic reaction; Figure 10 (f) shows the cyclic voltammetry curves of the CoPc-CN MDE molecularly dispersed electrocatalyst before and after the electrocatalytic reaction.

[0027] Figure 11 The in-situ attenuated total reflectance Fourier transform infrared spectrum is shown. in, Figure 11 (a) shows the in-situ attenuated total reflectance Fourier transform infrared spectra of CO adsorbed on a gold electrode under different carbon monoxide pressures; Figure 11 (b) shows the in-situ attenuated total reflectance Fourier transform infrared spectrum of formaldehyde after the addition of commercial formaldehyde; Figure 11 (c) shows the in-situ attenuated total reflectance Fourier transform infrared spectrum of methanol after the addition of commercial methanol.

[0028] Figure 12 The correlation between the adsorbed CO concentration and the formaldehyde / methanol Faraday efficiency ratio is shown. in, Figure 12 (a) shows the pressure dependence of the normalized CO adsorption area of ​​the methoxy-substituted cobalt phthalocyanine molecularly dispersed electrocatalyst at open circuit potential (normalized to 1.0 based on the maximum peak area at 50 bar). Figure 12 (b) shows a methoxy-substituted cobalt phthalocyanine molecularly dispersed electrocatalyst at -10 mA cm⁻¹ -2 Pressure dependence of the formaldehyde / methanol Faraday efficiency ratio at current density.

[0029] Figure 13 The mechanistic test results for the selectivity of pressure-regulated products are shown; in, Figure 13 (a) shows the in-situ attenuation total reflectance Fourier transform infrared spectra of CO adsorption by a methoxy-substituted cobalt phthalocyanine molecularly dispersed electrocatalyst under different carbon monoxide pressures; Figure 13 (b) shows the potential-dependent decay total reflectance Fourier transform infrared spectroscopy of a methoxy-substituted cobalt phthalocyanine molecularly dispersed electrocatalyst at 1 bar of carbon monoxide pressure; Figure 13 (c) shows the potential-dependent decay total reflectance Fourier transform infrared spectroscopy of the methoxy-substituted cobalt phthalocyanine molecularly dispersed electrocatalyst at 50 bar of carbon monoxide pressure; Figure 13 (d) shows the results at 1 bar and 50 bar carbon monoxide pressures, at -10 mA·cm⁻¹ -2 The concentrations of carbon monoxide and formaldehyde at the electrolyte-electrode interface were obtained through multi-scale simulation calculations during the electroreduction reaction of carbon monoxide at a given current density.

[0030] Figure 14 The peak areas of methanol and formaldehyde in in-situ attenuated total reflectance Fourier transform infrared spectra are shown.

[0031] Figure 15 The product distribution of the methoxy-substituted cobalt phthalocyanine molecularly dispersed electrocatalyst in different electrolytes is shown.

[0032] Figure 16 The large-scale preparation and application of formaldehyde based on the carbon monoxide electroreduction reaction are shown. in, Figure 16 (a) shows a schematic diagram of the gas diffusion electrode used in the high-pressure carbon monoxide electroreduction reaction; Figure 16 (b) shows the Faraday efficiency and formaldehyde current density of each product on the methoxy-substituted cobalt phthalocyanine molecularly dispersed electrocatalyst under high current conditions. Figure 16 (c) shows a current density of -100 mA·cm -2 The Faraday efficiency of each product and the change of applied potential during the 8-hour constant electrolysis of carbon monoxide electroreduction; Figure 16 (d) shows the bactericidal effect of the electrolyte after the electrocatalytic reaction characterized by an E. coli growth experiment; Figure 16(e) shows the synthesis of carbohydrate compounds from formaldehyde obtained by the electroreduction of carbon monoxide.

[0033] Figure 17 A physical image of the high-voltage electrochemical reactor used for testing the electroreduction performance of carbon monoxide is shown. in, Figure 17 (a) shows an H-type electrolytic cell; Figure 17 (b) shows the gas diffusion electrode (GDE) system.

[0034] Figure 18 The mass spectrum of the electrocatalytic product after benzylation is shown. Detailed Implementation

[0035] To more clearly illustrate the technical solution of the present invention, the following embodiments are provided. Unless otherwise stated, the raw materials, reactions, and post-processing methods appearing in the embodiments are all commercially available raw materials and technical methods well known to those skilled in the art.

[0036] The terms "preferred," "more preferably," and "more suitable" used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0037] It should be understood that, except in any operational instance or otherwise indicated, the amounts or all figures representing ingredients used, for example, in the specification and claims, should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise stated, the numerical parameters set forth in the following specification and appended claims are approximate values ​​varying according to the desired performance to be obtained according to the invention.

[0038] The present invention uses the following materials: Carbon nanotubes (CNTs)

[0039] Cobalt phthalocyanine: CoPc.

[0040] Methoxy-substituted cobalt phthalocyanine: CoPc-OMe; 2,9(10),16(17),23(24)-tetramethoxycobalt phthalocyanine(II).

[0041] Cyanosubstituted cobalt phthalocyanine: CoPc-CN; 2,3,9,10,16,17,23,24-octacyanophthalocyanine cobalt(II).

[0042] Ionic polymer: Nafion, D-520.

[0043] Example 1 A method for the efficient electrocatalytic synthesis of formaldehyde from carbon monoxide includes the following steps: S1. 30 mg of CNT and 1.5 mg of CoPc were dispersed in DMF (20 mL and 10 mL of DMF, respectively), and sonicated in a water bath for 0.5 h to obtain CNT and CoPc suspensions. The two suspensions were mixed, sonicated for 1 h, and then stirred at 25 °C for 24 h to obtain a crude product. The crude product was centrifuged at 8700 rpm for 5 min, and the precipitate was washed twice each with DMF, ethanol, and ultrapure water, and then freeze-dried to obtain a cobalt phthalocyanine-based molecularly dispersed electrocatalyst (CoPcMDE). S2. Add 2 mg of the cobalt phthalocyanine-based molecularly dispersed electrocatalyst and the ionomer to 1 mL of ethanol, and disperse by ultrasonication to obtain an ethanol dispersion (the ionomer accounts for 0.0325 wt% of the total mass of the ethanol dispersion); drop-coat the ethanol dispersion onto polytetrafluoroethylene-treated carbon paper (Toray 060, 50% PTFE, Fuel Cell Store), with a catalyst loading of 0.4 mg·cm⁻¹. -2 (Geometric area: 0.5 cm²) 2 ), to obtain a cobalt phthalocyanine-based molecularly dispersed electrocatalyst electrode; S3. Install the phthalocyanine cobalt-based molecularly dispersed electrocatalyst electrode in a commercial high-pressure H-type electrolytic cell system (pressure-resistant type, equipped with a calibrated pressure gauge). The electrolyte is a 0.1 M potassium bicarbonate solution. Continuously purge high-purity CO (99.999%) into the anode and cathode chambers. After the electrolyte is saturated, close the gas outlet, pressurize the electrolytic cell with CO to 90 bar, and maintain this pressure for 20 min to establish gas-liquid equilibrium. Then, pressurize the electrolytic cell to -10 mA·cm⁻¹. -2 A constant-current CO electroreduction reaction was carried out at a certain current density, and the liquid product was collected to obtain formaldehyde.

[0044] Example 2 A method for the efficient electrocatalytic synthesis of formaldehyde from carbon monoxide is disclosed. The difference between this embodiment and Example 1 is that in step S1, CoPc is replaced with CoPc-OMe, and the cobalt content in the electrocatalyst is ensured to be consistent with that in Example 1 by adjusting the ratio of CNT to CoPc-OMe, thereby obtaining a cobalt phthalocyanine-based molecularly dispersed electrocatalyst (CoPc-OMe MDE). Other steps and dosages are the same as in Example 1.

[0045] Example 3 A method for the efficient synthesis of formaldehyde from carbon monoxide via electrocatalysis. The difference between this embodiment and Example 1 is that in step S1, CoPc is replaced with CoPc-CN, and the cobalt content in the electrocatalyst is ensured to be consistent with that in Example 1 by adjusting the ratio of CNT to CoPc-CN, thereby obtaining a cobalt phthalocyanine-based molecularly dispersed electrocatalyst (CoPc-CN MDE). Other steps and dosages are the same as in Example 1.

[0046] Comparative Example 1 A method for the efficient electrocatalytic synthesis of formaldehyde from carbon monoxide. The difference between this comparative example and Example 2 is that step S1 is omitted, and step S2 is modified as follows: 1 mg of CoPc-OMe, 1 mg of CNT, and the ionomer were added to 1 mL of ethanol and ultrasonically dispersed to obtain an ethanol dispersion (the amount of ionomer was the same as in Example 2). The ethanol dispersion was drop-coated onto polytetrafluoroethylene-treated carbon paper (Toray 060, 50% PTFE, Fuel Cell Store) with a catalyst loading of 0.4 mg·cm⁻¹. -2 (Geometric area: 0.5 cm²) 2 ), to obtain a cobalt phthalocyanine-based molecularly dispersed electrocatalyst electrode; The other steps and dosages are the same as in Example 1.

[0047] Comparative Example 2 A method for the efficient electrocatalytic synthesis of formaldehyde from carbon monoxide. The difference between this comparative example and Example 2 is that step S1 is omitted, and step S2 is modified as follows: 1 mg of CoPc-OMe and the ionomer were added to 1 mL of ethanol and ultrasonically dispersed to obtain an ethanol dispersion (the amount of ionomer was the same as in Example 2). The ethanol dispersion was drop-coated onto polytetrafluoroethylene-treated carbon paper (Toray 060, 50% PTFE, Fuel Cell Store) with a catalyst loading of 0.4 mg·cm⁻¹. -2 (Geometric area: 0.5 cm²) 2 ), to obtain a cobalt phthalocyanine-based molecularly dispersed electrocatalyst electrode; The other steps and dosages are the same as in Example 1.

[0048] Figure 1 The diagram shows different formaldehyde production routes and a comparison of the Faraday efficiency and local current density for the electrocatalytic preparation of different products. in, Figure 1 (a) shows a schematic diagram of different formaldehyde production routes; by Figure 1(a) It can be seen that the traditional industrial synthesis of formaldehyde requires a multi-step redox cascade process under harsh conditions, while the one-pot electrosynthesis technology proposed in this invention can use green electricity to reduce CO2 / CO to formaldehyde. Figure 1 (b) shows a comparison of the Faraday efficiency for the electrocatalytic preparation of different products; Figure 1 (c) shows a comparison of the local current densities of different products; by Figure 1 (b) Figure 1 (c) It can be seen that the performance of electrocatalytic reduction of CO2 / CO to formaldehyde is relatively limited, which is in stark contrast to the excellent performance of electrocatalytic preparation of various products such as methanol, methane, acetic acid, ethylene, ethanol and allyl alcohol.

[0049] Figure 2 The C1 conversion pathway of CO2 reduction on a cobalt phthalocyanine-based molecularly dispersed electrocatalyst and the high-angle annular dark-field scanning transmission electron microscope image of the CoPc-OMe MDE are shown. in, Figure 2 (a) illustrates the C1 conversion pathway of CO2 reduction on a cobalt phthalocyanine-based molecularly dispersed electrocatalyst; Figure 2 (b) shows a high-angle annular dark-field scanning transmission electron microscope image of the CoPc-OMe MDE.

[0050] Test Example 1 All electrochemical measurements in this invention employ a three-electrode system, using a CHI 760E electrochemical workstation or a DH7001 electrochemical workstation (for gas diffusion electrode experiments). Formaldehyde reduction and carbon monoxide electroreduction experiments were conducted in a commercial high-pressure H-type electrolytic cell system (pressure-resistant type, equipped with a calibrated pressure gauge). This system includes a reference electrode (Ag / AgCl, saturated potassium chloride solution), a counter electrode (platinum sheet), and an anion exchange membrane (Fumasep). ® FAA-3). The potential is recorded relative to the Ag / AgCl reference electrode and converted to the reversible hydrogen electrode (RHE) scale using the following formula: E RHE =E Ag / AgCl +0.197 V+0.059×pH-0.85×iR; in, iR correction is applied to 85% of the uncompensated resistance, where i is the average current and R is the solution resistance.

[0051] The electrolyte for formaldehyde electroreduction was a 0.1 M potassium bicarbonate solution containing 25 mM formaldehyde, and the electrolyte for carbon monoxide electroreduction was a 0.1 M potassium bicarbonate solution or phosphate-buffered saline (PBS, pH 7.0); 0.1 M potassium bicarbonate was provided via KH₂PO₄ / K₂HPO₄. + (Ions). High-purity carbon monoxide (99.999%) or argon (99.999%) is continuously introduced into the anode and cathode chambers. In the atmospheric pressure experiment (1 bar), the electrolyte is initially introduced at 20 sccm (standard cm·min). -1 The system was pre-saturated with gas at a flow rate of 10 min, and the gas flow was maintained during the test. In the high-pressure experiment, the gas outlet was closed after the electrolyte was saturated, and the electrolytic cell was pressurized. Before electrochemical measurements, the system was maintained at the target pressure for 20 min to establish gas-liquid equilibrium.

[0052] The turnover number (TON) value is calculated based on the catalyst loading on the matrix and the metal content in the catalyst, assuming full electrochemical accessibility to all metal sites. This assumption provides a conservative estimate, representing the lower limit of the practical TON value. The reported FE and potential values ​​reflect the average of at least three independent measurements.

[0053] Numerical methods: Two-dimensional simulations were performed in COMSOL Multiphysics, incorporating species concentration modeling in the electrolyte. Steady-state solutions at operating pressures of 1 bar or 50 bar were calculated to compare their effects. The mesh was validated by selecting an extremely fine mesh and adding a boundary layer near the electrode surface for refinement.

[0054] The process of establishing a pressure-regulated competitive adsorption strategy for carbon monoxide: (1) By calculating the adsorption energy difference (G) ad (HCHO) and G ad (CO) was used to investigate the competitive adsorption behavior of formaldehyde and carbon monoxide on cobalt phthalocyanine molecules.

[0055] Three molecular systems were compared: CoPc, CoPc-OMe, and CoPc-CN. The selected substituents play a crucial role in modulating the electronic structure of the cobalt center through their unique electron-donating (methoxy) and electron-withdrawing (cyano) effects. Notably, the methoxy substituent simultaneously inhibits formaldehyde adsorption and enhances carbon monoxide adsorption; therefore, CoPc-OMe exhibits a lower G than CoPc and CoPc-CN. ad (CO)−G ad (HCHO) value.

[0056] The calculation results are as follows Figure 3 As shown.

[0057] Figure 3The intrinsic substituent regulation of CoPc and the comparison of its calculated adsorption energies for carbon monoxide and formaldehyde are shown. in, Figure 3 (a) illustrates the intrinsic substituent regulation of CoPc; Figure 3 (b) shows a comparison of the calculated adsorption energies of CoPc, CoPc-CN, and CoPc-OMe for carbon monoxide and formaldehyde.

[0058] The calculation results show that carbon monoxide on CoPc-OMe has a higher intrinsic advantage in competitive adsorption relative to formaldehyde, which can inhibit excessive reduction of formaldehyde.

[0059] (2) Linear scanning voltammetry (LSV) test.

[0060] Test method: To verify the above predictions, CoPc, CoPc-OMe, and CoPc-CN were immobilized on carbon nanotubes to prepare molecularly dispersed electrocatalysts (MDEs): CoPc-OMe MDE, CoPc MDE, and CoPc-CN MDE, with a cobalt loading of approximately 0.3 wt%. This design ensures rapid electron transport to the catalytic center through the conductive carbon nanotube network and maximizes the accessibility of active sites, which is beneficial for exhibiting the inherent activity of the molecular catalyst. LSV tests were performed on the three molecularly dispersed electrocatalysts in an electrolyte with a formaldehyde concentration of 25 mM and a potassium bicarbonate concentration of 0.1 M.

[0061] Test results are as follows Figure 4-5 As shown.

[0062] Figure 4 The diagrams show the direct electroreduction of formaldehyde under normal pressure and the inhibitory effect of formaldehyde electroreduction under high pressure CO conditions. in, Figure 4 (a) shows a schematic diagram of the direct electroreduction of formaldehyde under normal pressure; Figure 4 (b) shows a schematic diagram of the inhibitory effect of formaldehyde electroreduction under high pressure CO conditions.

[0063] Figure 5 The LSV curves of formaldehyde electroreduction catalyzed by three cobalt phthalocyanine-based molecularly dispersed electrocatalysts and the LSV curves of formaldehyde electroreduction catalyzed by CoPc-OMe MDE under different carbon monoxide pressures are shown. in, Figure 5 (a) shows the LSV curves of formaldehyde electroreduction catalyzed by three cobalt phthalocyanine-based molecularly dispersed electrocatalysts; Figure 5(b) shows the LSV curves of CoPc-OMe MDE for the electroreduction of formaldehyde under different carbon monoxide pressures.

[0064] The test results show that, compared with the condition without formaldehyde, the electrocatalyst exhibits obvious formaldehyde reduction activity (enhanced cathodic current). Substituent-dependent regulation of the reduction potential was also observed: the potentials of CoPc-OMe MDE, CoPc MDE, and CoPc-CN MDE at a current density of -3 mA·cm -2 are -0.41, -0.40, and -0.38 V (versus the reversible hydrogen electrode, RHE), respectively. This trend is inversely proportional to the calculated formaldehyde adsorption energy (G ad (HCHO)): CoPc-CN < CoPc < CoPc-OMe (this result can also be seen from Figure 3 (b)).

[0065] To further investigate the inhibitory effect of carbon monoxide on the over-reduction of formaldehyde, we introduced carbon monoxide gas into the electrolyte during the electroreduction of formaldehyde, and the test results are shown in Figure 5 (b).

[0066] As can be seen from Figure 5 (b), at 1 bar carbon monoxide (about 0.95 mM in solution), the formaldehyde reduction current on CoPc-OMe MDE decreased by 26% (from -7.6 mA·cm -2 to -5.6 mA·cm -2 at -0.5 V (versus RHE potential), where carbon monoxide reduction is unfavorable); while at 50 bar carbon monoxide (47 mM in solution), the inhibitory effect is more significant, and the current decreased by 84% (to -0.92 mA·cm -2 ). The control experiment with 50 bar argon shows that the activity loss is negligible, excluding pressure artifacts and confirming that carbon monoxide adsorption is the main inhibitory mechanism. It is worth noting that the activity of the hydrogen evolution reaction (HER) is also inhibited under high-pressure carbon monoxide, highlighting the strong blocking effect of carbon monoxide on the active sites of CoPc-OMe.

[0067] Based on the experimental results of formaldehyde reduction, the present invention established a pressure-regulated carbon monoxide competitive adsorption strategy for the selective electrosynthesis of formaldehyde by electroreduction of carbon monoxide, and the schematic diagram of the reaction path is as shown in Figure 6 .

[0068] Figure 6 shows a schematic diagram of the inhibition of the further reduction of formaldehyde by the competitive adsorption of high-pressure carbon monoxide.

[0069] (3) Product quantitative test.

[0070] The product of Example 2 was quantitatively tested.

[0071] Test method: Quantitative analysis of gaseous products: Gaseous products were collected in a 20 L balloon, equilibrated for 10 min, and then analyzed by online gas chromatography (GC, 9720 Plus, Fuli Instruments).

[0072] Quantitative analysis of liquid-phase products: Quantitative analysis of liquid-phase carbon products (such as formaldehyde and methanol) is performed by mixing the electrolyte (400 μL) after the reaction with heavy water (100 μL) containing potassium benzoate (10 mmol, internal standard). 13 C nuclear magnetic resonance (C10) 13 It is achieved through CNMR (Central Magnetic Resonance Spectroscopy) analysis.

[0073] Formaldehyde quantification: Method 1: Using 1 H nuclear magnetic resonance (H nuclear magnetic resonance) 1 Quantification was performed using the 1H NMR method. To solve... 1 To address the signal overlap issue between water molecules and formaldehyde in H NMR, the electrolyte (50 mL) after the reaction was derivatized with saturated hydroxylamine hydrochloride (3 mL) before preparing the NMR sample.

[0074] Method 2: Quantification was performed using ultraviolet-visible (UV-Vis) spectrophotometry. When quantifying formaldehyde in the electrolyte using UV-Vis spectrophotometry, 10 mL of the reacted electrolyte was mixed with 2 mL of acetylacetone reagent solution and heated in boiling water for 3 min to promote derivatization. The preparation method of acetylacetone reagent is as follows: 25 g of ammonium acetate and 3 mL of glacial acetic acid were dissolved in deionized water, 0.25 mL of acetylacetone was added, and the solution was diluted to 100 mL. The pH was adjusted to 6.0 with hydrochloric acid or sodium hydroxide solution.

[0075] Test results are as follows Figure 7 As shown.

[0076] Figure 7 The electrolyte sample is shown. 13 C NMR and 1 The magnified area of ​​the H NMR spectrum, as well as the UV-Vis spectrum used for colorimetric quantification of formaldehyde and photographs of the solution before and after the reaction; in, Figure 7 (a) shows the electrolyte sample. 13 C NMR and 1 The magnified region of the H NMR spectrum; by Figure 7 (a) This confirms the formation of formaldehyde; Figure 7(b) shows the UV-Vis spectrum used for colorimetric quantification of formaldehyde and photographs of the solution before and after the reaction; by Figure 7 (b) It can be seen that the generated formaldehyde reacts with acetylacetone and ammonium acetate to form a yellow diacetyl dihydrolutidine complex.

[0077] Gas chromatography analysis showed that hydrogen was the only gaseous byproduct. It is noteworthy that... Figure 7 (a) It can be seen that, through 13 Free formaldehyde was directly detected by NMR in the liquid phase, with a significantly higher signal intensity than that of adjacent methanol. Subsequently, it was derivatized with hydroxylamine (NH₂-OH) and detected by... 1 ¹H NMR confirmed the formation of formaldehyde oxime (H₂C=NOH), thus enabling the quantitative determination of formaldehyde. Spectrophotometric analysis further verified the accumulation of formaldehyde in the solution, revealing a characteristic absorption peak at 413 nm (the maximum absorption wavelength of the diacetyl dihydrorutidine complex), the intensity of which was quantitatively correlated with the formaldehyde concentration.

[0078] (4) Gas Diffusion Electrode (GDE) Experiment.

[0079] Test method: The gas diffusion electrode experiment was conducted in a self-made high-pressure container (volume: 3 L) containing a three-chamber electrochemical cell (gas chamber, cathode chamber, and anode chamber). The working electrode had a window with a diameter of 0.8 cm and an effective geometric area of ​​0.5 cm². 2 .

[0080] The gas diffusion electrode is prepared by: using the ethanol dispersion from Example 2 (containing 2 mg / ml of cobalt phthalocyanine-based molecularly dispersed electrocatalyst). -1 The catalyst (containing 0.0325 wt% Nafion) was drop-coated onto a microporous carbon layer of commercial gas diffusion carbon paper (GDL, SGL39BB, Fuel Cell Store). The final catalyst loading was 0.6 mg·cm⁻¹. -2 The total electrode area is 1.5 × 1.5 cm. 2 During testing, 0.2 M phosphate-buffered saline (PBS, pH 7.0) pre-saturated with argon gas was used as the electrolyte. Residual air was replaced with carbon monoxide gas, and the pressure was increased to 90 bar after the gas outlet was closed. The system was allowed to equilibrate for 20 min to stabilize the gas-liquid dissolution before electrochemical measurements were performed. The electrodes were operated in constant current mode, with each current density maintained for 1000 s to determine the steady-state Faraday efficiency (FE).

[0081] Test results are as follows Figure 8-9 As shown.

[0082] Figure 8The total current density is shown to be -10 mA·cm. -2 At the same time, FE and j under different carbon monoxide applied pressures HCHO And under a carbon monoxide pressure of 90 bar, the FE and j corresponding to different applied potentials HCHO ; in, Figure 8 (a) shows a total current density of -10 mA·cm -2 At the same time, FE and j under different carbon monoxide applied pressures HCHO ; Figure 8 (b) shows the FE and j corresponding to different applied potentials under a carbon monoxide pressure of 90 bar. HCHO .

[0083] Figure 9 The selectivity for formaldehyde production from carbon monoxide via electrocatalysis is shown as a function of carbon monoxide pressure and potential. All electrocatalytic tests were conducted in a 0.1 M potassium bicarbonate electrolyte saturated with carbon monoxide.

[0084] Depend on Figure 8 (a) It can be seen that at atmospheric pressure (1 bar), when the operating current density is -10 mA·cm -2 At that time, the Faraday efficiency (FE) of formaldehyde electrosynthesis HCHO The current density is 6%, with a partial current density of -0.6 mA·cm⁻¹. -2 It is significantly lower than the methanol (FE) produced at the same time. CH3OH (28%). These data are consistent with earlier studies reporting that, in similar electrochemical environments, the formaldehyde Faraday efficiency is approximately 5%, with a partial current density (j HCHO The value is -0.1 mA·cm. -2 It is noteworthy that increasing the carbon monoxide pressure to 90 bar dramatically enhances formaldehyde selectivity: the Faraday efficiency increases from 6% to 72%. HCHO Reaching -18 mA·cm -2 This marks the first successful direct and efficient electrosynthesis of formaldehyde from carbon monoxide, surpassing previous benchmarks (Faraday efficiency <17% at 10°C). HCHO <0.65 mA·cm -2 ).

[0085] Depend on Figure 9 It can be seen that the selectivity for the conversion of carbon monoxide to formaldehyde increased from 32% at 1 bar to 94% at 90 bar. This change is attributed to the increased carbon monoxide concentration in the solution, which promoted competitive adsorption and inhibited excessive formaldehyde reduction. Meanwhile, the total Faraday efficiency (FE) of the C1 product also increased. HCHO+CH3OHThe hydrogen Faraday efficiency (FE) is significantly improved, while the hydrogen evolution reaction is suppressed, resulting in a significant increase in the hydrogen Faraday efficiency. H2 Under high pressure carbon monoxide, it decreased from 67% to 9.8%.

[0086] Depend on Figure 8 (b) It can be seen that under a carbon monoxide pressure of 90 bar, the formaldehyde Faraday efficiency exhibits a volcano-like relationship with the applied potential, reaching a peak of 72% at -0.79 V. Conversely, the methanol Faraday efficiency steadily increases with increasing cathode polarization. Meanwhile, from Figure 9 It can be seen that when the potential changes from -0.68 V to -0.95 V, the selectivity for the conversion of carbon monoxide to formaldehyde decreases from 98% to 76%. This indicates that at lower potentials, formaldehyde is more likely to be reduced to methanol. The measured formaldehyde selectivity order is CoPc-OMe > CoPc > CoPc-CN, consistent with the calculated G. ad (CO)-G ad The results for (HCHO) were consistent. A control experiment with CoPc-OMe without carbon nanotubes showed no formaldehyde generation at -0.96 V, a methanol Faraday efficiency of only 17%, and a total current density as low as -0.5 mA·cm⁻¹. -2 Scanning electron microscopy (SEM) images showed significant molecular aggregation of the original CoPc-OMe, indicating that molecular aggregation hinders the efficient conversion of carbon monoxide and exacerbates the excessive reduction of formaldehyde.

[0087] Test Example 2 Long-term stability testing.

[0088] Test method: The test method of “(4) Gas diffusion electrode (GDE) experiment” in Test Example 1 was adopted to continuously test CoPcMDE, CoPc-OMe MDE and CoPc-CN MDE for 8 hours.

[0089] Test results are as follows Figure 10 As shown.

[0090] Figure 10 The long-cycle electrocatalytic performance of the cobalt phthalocyanine-based molecularly dispersed electrocatalyst is demonstrated. in, Figure 10 (a) shows the liquid-phase product Faraday efficiency and the change in applied potential of a methoxy-substituted cobalt phthalocyanine molecularly dispersed electrocatalyst for the electroreduction of carbon monoxide; Figure 10 (b) shows the corresponding performance data for the cobalt phthalocyanine molecularly dispersed electrocatalyst; Figure 10 (c) shows the corresponding performance data of the cyano-substituted cobalt phthalocyanine molecularly dispersed electrocatalyst; Figure 10(d) shows the cyclic voltammetry curves before and after the electrocatalytic reaction of the CoPc-OMe MDE molecularly dispersed electrocatalyst; Figure 10 (e) shows the cyclic voltammetry curves of the CoPc MDE molecularly dispersed electrocatalyst before and after the electrocatalytic reaction; Figure 10 (f) shows the cyclic voltammetry curves of the CoPc-CN MDE molecularly dispersed electrocatalyst before and after the electrocatalytic reaction. Figure 10 All tests were performed in 0.1 mol / L potassium bicarbonate electrolyte; long-cycle stability tests were conducted under the following conditions: 60 bar carbon monoxide atmosphere, -10 mA cm⁻¹. -2 Constant current density; cyclic voltammetry was performed at 1 bar atmospheric pressure with a scan rate of 200 mV / s. -1 .

[0091] Long-term stability tests showed significant differences in the stability of the three cobalt phthalocyanine-based molecularly dispersed electrocatalysts: the overpotential of the cobalt phthalocyanine-based molecularly dispersed electrocatalyst increased slowly over 6 hours, with an increase of 67 mV; while the overpotential of the cyano-substituted cobalt phthalocyanine-based molecularly dispersed electrocatalyst increased dramatically within only 2 hours, with an increase of 455 mV (see...). Figure 10 (a)-10(c)). Cyclic voltammetry characterization of the catalysts before and after the electrocatalytic reaction confirmed that the molecularly dispersed electrocatalysts of cobalt phthalocyanine and cyano-substituted cobalt phthalocyanine have relatively poor stability (see...). Figure 10 (e)-10(f)); In contrast, the cyclic voltammetry curves of the methoxy-substituted cobalt phthalocyanine molecularly dispersed electrocatalyst before and after the reaction almost completely overlap, exhibiting excellent electrochemical stability (see […]). Figure 10 (d)).

[0092] Test Example 3 Pressure-dependent mechanism of carbon monoxide electroreduction.

[0093] Test method: In-situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) measurements were performed in a commercially available high-voltage H-type electrochemical cell equipped with a reference electrode (Ag / AgCl electrode in saturated potassium chloride solution), a counter electrode (platinum sheet), and an anion exchange membrane. The working electrode was prepared by drop-coating a CoPc-OMe molecularly dispersed electrocatalyst ink onto a gold-plated silicon prism window of a Nicolet iS50 Fourier transform infrared spectrometer (Thermo Fisher Scientific). The electrolyte was a 0.1 M potassium bicarbonate solution. Spectra were collected at 0.03 V intervals during a linear potential scan from 0 V to -2.5 V (relative to Ag / AgCl). Background spectra were acquired at the open-circuit potential (OCP) prior to the electrochemical measurements to correct for baseline absorption.

[0094] Test results are as follows Figure 11-12 As shown.

[0095] Figure 11 The in-situ attenuated total reflectance Fourier transform infrared spectrum is shown. in, Figure 11 (a) shows the in-situ attenuated total reflectance Fourier transform infrared spectra of CO adsorbed on a gold electrode under different carbon monoxide pressures; Figure 11 (b) shows the in-situ attenuated total reflectance Fourier transform infrared spectrum of formaldehyde after the addition of commercial formaldehyde; Figure 11 (c) shows the in-situ attenuated total reflectance Fourier transform infrared spectrum of methanol after the addition of commercial methanol. The upward peak shape changes in each wavenumber range correspond to the adsorption behavior of CO, formaldehyde, and methanol, respectively. The electrolyte is a 0.1 mol / L potassium bicarbonate solution.

[0096] Figure 12 The correlation between the adsorbed CO concentration and the formaldehyde / methanol Faraday efficiency ratio is shown. in, Figure 12 (a) shows the pressure dependence of the normalized CO adsorption area of ​​the methoxy-substituted cobalt phthalocyanine molecularly dispersed electrocatalyst at open circuit potential (normalized to 1.0 based on the maximum peak area at 50 bar). Figure 12 (b) shows a methoxy-substituted cobalt phthalocyanine molecularly dispersed electrocatalyst at -10 mA cm⁻¹ -2 Pressure dependence of the formaldehyde / methanol Faraday efficiency ratio at current density.

[0097] The pressure-dependent mechanism of carbon monoxide electroreduction on CoPc-OMe MDE was investigated using in-situ attenuated total reflectance Fourier transform infrared spectroscopy. The results showed that in 0.1 M potassium bicarbonate, a 2100 cm⁻¹ spectral density attributable to adsorbed carbon monoxide appeared at an open-circuit potential. -1 The peak is observed, and its intensity increases when the carbon monoxide pressure exceeds 5 bar. Control experiments on bare gold substrates show that this peak is negligible (see [link to control experiments]). Figure 11 (a) indicates that carbon monoxide binds only to the active sites of CoPc-OMe. At low carbon monoxide pressures (1–5 bar), the peak area integral of carbon monoxide increases sharply, while the increase slows down under high pressure, consistent with the change in the Faraday efficiency ratio of HCHO / CH3OH (see [link to article]). Figure 12 This correlation indicates that formaldehyde selectivity is strongly regulated by carbon monoxide adsorption behavior.

[0098] Test Example 4 Operational potential dependence analysis of carbon monoxide electroreduction.

[0099] Test method: In-situ attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was used to investigate the pressure-dependent mechanism of carbon monoxide electroreduction reaction on a methoxy-substituted cobalt phthalocyanine molecularly dispersed electrocatalyst.

[0100] Test results are as follows Figure 13 , Figure 11 (b) 11 (c) Figure 14 , Figure 15 As shown.

[0101] Figure 13 The mechanistic test results for the selectivity of pressure-regulated products are shown; in, Figure 13 (a) shows the in-situ attenuation total reflectance Fourier transform infrared spectra of CO adsorption by a methoxy-substituted cobalt phthalocyanine molecularly dispersed electrocatalyst under different carbon monoxide pressures; Figure 13 (b) shows the potential-dependent decay total reflectance Fourier transform infrared spectroscopy of a methoxy-substituted cobalt phthalocyanine molecularly dispersed electrocatalyst at 1 bar of carbon monoxide pressure; Figure 13 (c) shows the potential-dependent decay total reflectance Fourier transform infrared spectroscopy of the methoxy-substituted cobalt phthalocyanine molecularly dispersed electrocatalyst at 50 bar of carbon monoxide pressure; Figure 13 (d) shows the results at 1 bar and 50 bar carbon monoxide pressures, at -10 mA·cm⁻¹ -2 The concentrations of carbon monoxide and formaldehyde at the electrolyte-electrode interface during the electroreduction reaction of carbon monoxide at a given current density were obtained through multi-scale simulation calculations. The values ​​shown in the figure represent the surface concentration at a distance of 0 micrometers from the electrode.

[0102] Figure 14 The peak areas of methanol and formaldehyde in in-situ attenuated total reflectance Fourier transform infrared spectra are shown. The spectra were recorded in a 50 bar carbon monoxide atmosphere at a potential of approximately -0.8 V relative to a reversible hydrogen electrode.

[0103] Figure 15 The product distribution of the methoxy-substituted cobalt phthalocyanine molecularly dispersed electrocatalyst in different electrolytes is shown. Under a 90 bar carbon monoxide atmosphere and -10 mA cm⁻¹ atmosphere... -2At a current density of 0.1 mol / L potassium bicarbonate electrolyte, the formaldehyde Faradaic efficiency and the formaldehyde / methanol Faradaic efficiency ratio of the methoxy-substituted cobalt phthalocyanine molecularly dispersed electrocatalyst in dipotassium hydrogen phosphate-potassium dihydrogen phosphate electrolyte (total potassium ion concentration 0.1 mol / L) are slightly lower.

[0104] Test results showed that at 1 bar of carbon monoxide, when -0.05 V (relative to the RHE potential) was applied, a 1640 cm⁻¹ was observed. -1 The C=O stretching vibration peak was attributed to the formation of CHO or HCHO, a finding confirmed by standard formaldehyde control experiments (see [link to experiment]). Figure 11 (b) When the potential dropped further to -0.2 V, a new 1400 cm⁻¹ appeared. -1 The peak corresponds to the OH bending vibration mode of CH3OH (see...). Figure 11 (c)), while the CHO / HCHO signal is weakened (see Figure 13 (b) This continuous conversion from formaldehyde to methanol explains the low selectivity of formaldehyde (Faraday efficiency of approximately 6%) in the atmospheric pressure carbon monoxide electroreduction. This necessitates the desorption of formaldehyde from the catalyst surface to prevent further reduction. At 50 bar carbon monoxide, the CHO / HCHO peak intensity at approximately -0.69 V increased 30-fold compared to the 1 bar condition (see [link to article]). Figure 13 (c) It is noteworthy that even at -0.8 V (the potential at which formaldehyde is almost completely converted to methanol at 1 bar), a formaldehyde signal could still be detected, with a signal area ratio of 16 between formaldehyde and methanol (see [reference]). Figure 14 This indicates that very little methanol has accumulated.

[0105] Through -10 mA·cm -2 By performing multi-scale computational simulations of the electrolyte-electrode interface at current densities, we elucidate the pressure-dependent concentration of C1 compounds in the electroreduction of carbon monoxide (see...). Figure 13(d) At 1 bar of carbon monoxide, the bulk carbon monoxide concentration was 0.95 mM, and carbon monoxide was rapidly consumed near the electrolyte-electrode interface. This consumption resulted in a carbon-depleted microenvironment with a low interfacial carbon monoxide concentration (0.13 mM). In contrast, upon pressurizing to 50 bar of carbon monoxide, the relative concentration at the electrolyte-electrode interface reversed. The bulk carbon monoxide concentration increased to 47 mM (a 50-fold increase), and despite the accelerated carbon monoxide consumption (formaldehyde Faradaic efficiency 66%, methanol Faradaic efficiency 13%), the residual interfacial concentration remained at 44 mM. This resulted in a 300-fold increase in the molar amount of carbon monoxide compared to the 1 bar condition, and a 7-fold increase compared to the locally generated formaldehyde (5.9 mM). The excess carbon monoxide promoted the desorption of formaldehyde from the active sites while inhibiting proton adsorption to reduce hydrogen evolution (hydrogen Faradaic efficiency: <19% at 50 bar, 67% at 1 bar).

[0106] Formaldehyde serves as a universal C1 building block, enabling the microbial synthesis of complex molecules through natural extension pathways, and breakthroughs in protein engineering have now led to product diversification. To achieve in-situ formaldehyde generation that can be directly used for biosynthesis and eliminates the separation step, we employed a biocompatible phosphate-buffered saline (PBS) system (0.1 M potassium dihydrogen phosphate / dipotassium hydrogen phosphate, pH 7.0) to synthesize formaldehyde in situ via carbon monoxide electroreduction. The synthesis was carried out at 90 bar carbon monoxide pressure and -10 mA·cm⁻¹. -2 At the given current density, the formaldehyde Faraday efficiency of this system is 62%, slightly lower than the 72% under the 0.1 M potassium bicarbonate condition (see [reference needed]). Figure 15 It is worth noting that the carbon-free PBS electrolyte also confirmed that formaldehyde originated entirely from carbon monoxide reduction.

[0107] Test Example 5 Industrial production methods.

[0108] To achieve industrial-related production rates, this invention employs a gas diffusion electrode due to its rapid carbon monoxide mass transfer kinetics.

[0109] Test results are as follows Figure 16 , 17 As shown.

[0110] Figure 16 The large-scale preparation and application of formaldehyde based on the carbon monoxide electroreduction reaction are shown. in, Figure 16 (a) shows a schematic diagram of the gas diffusion electrode used in the high-pressure carbon monoxide electroreduction reaction; Figure 16(b) shows the Faraday efficiency and formaldehyde current density of each product on the methoxy-substituted cobalt phthalocyanine molecularly dispersed electrocatalyst under high current conditions. Figure 16 (c) shows a current density of -100 mA·cm -2 The Faraday efficiency of each product and the change of applied potential during the 8-hour constant electrolysis of carbon monoxide electroreduction were studied. The electrolyte was a 0.2 mol / L phosphate buffer solution (potassium dihydrogen phosphate / dipotassium hydrogen phosphate, pH=7.0). Figure 16 (d) shows the bactericidal effect of the electrolyte after the electrocatalytic reaction characterized by an E. coli growth experiment; Figure 16 (e) illustrates the synthesis of carbohydrate compounds from formaldehyde obtained by the electroreduction of carbon monoxide. The figure shows the sugar solution (left) and the control solution (right) obtained by the reaction of formaldehyde polysaccharide with formaldehyde obtained by the electroreduction of carbon monoxide. Yellow is the characteristic color of the generated sugar. In the proton nuclear magnetic resonance spectrum of the carbon monoxide electroreduction group, the characteristic proton signal of carbohydrate generation appeared at the chemical shift of 3.5-5 ppm.

[0111] Figure 17 A physical image of the high-voltage electrochemical reactor used for testing the electroreduction performance of carbon monoxide is shown. in, Figure 17 (a) shows an H-type electrolytic cell; Figure 17 (b) shows the gas diffusion electrode (GDE) system.

[0112] CoPc-OMe MDE was subjected to 0.2 M PBS (pH 7.0) and 90 bar of carbon monoxide, and the temperature ranged from -60 to -300 mA·cm⁻¹. -2 It exhibits stable operation within the current density range (see) Figure 16 (b) -60 mA·cm -2 At that time, the formaldehyde Faraday efficiency exceeded 57%, increasing with current density up to -300 mA·cm⁻¹. -2 The Faraday efficiency gradually decreased to 38%, while the peak current density of the formaldehyde portion reached -114 mA·cm. -2 This resulted in a yield of 4.5 × 10⁻⁶. 6 mol·gcat -1 ·h -1 This established a benchmark for large-scale CO-to-HCHO synthesis, achieving a performance improvement of 10 orders of magnitude compared to the best thermocatalytic route. (At -100 mA·cm⁻¹) -2 Electrolysis was carried out for more than 8 hours (see) Figure 16(c) The average Faraday efficiency was 44% for formaldehyde and 26% for methanol, with a total turnover (TON) of 198,307 (assuming all CoPc-OMe molecules are electrochemically accessible). The final electrolyte contained 500 ppm formaldehyde and 157 ppm methanol, with a formaldehyde to methanol mass ratio of approximately 3.2, highly consistent with the ratio in commercial sterilization formulations.

[0113] Test Example 6 Sterilization experiment.

[0114] Test method: Escherichia coli BL21 chemocompetent cells were inoculated into 10 mL of fresh LB medium (containing 50 ng·μL). -1 In kanamycin, the cells were cultured overnight at 37°C and 800 rpm with shaking. After recovery, E. coli BL21 cells were diluted 1:1000 in 1L of LB medium containing kanamycin and divided into three groups: (1) 0.2 M PBS with 30 ppm methanol as a control; (2) electrolyte with carbon monoxide electroreduction; and (3) electrolyte without carbon monoxide electroreduction. All groups were cultured in a constant temperature shaker at 37°C and 400 rpm. The absorbance (OD) at 600 nm was measured periodically. 600 ), to assess cell proliferation rate.

[0115] Test results are as follows Figure 16 As shown in (d).

[0116] Figure 16 (d) shows the bactericidal effect of the electrolyte after the electrocatalytic reaction characterized by an Escherichia coli growth experiment.

[0117] The test results above show that the Escherichia coli growth experiment verified the bactericidal effect of the product of this invention (see...). Figure 16 (d) In the control sample with electrolyte that had not undergone carbon monoxide electroreduction, an exponential increase was observed, with the absorbance at 600 nm (OD) increasing within 500 min. 600 The formaldehyde concentration increased from 0.06 to 0.91. In contrast, the electrolyte, after carbon monoxide electroreduction treatment and a final formaldehyde concentration of 100 ppm, completely inhibited bacterial growth, and the OD... 600 Stabilized at the initial value. The control sample containing only methanol (30 ppm in electrolyte) maintained a high survival rate, with the final OD... 600 The value was 0.84. These results confirm that the formaldehyde solution synthesized by carbon monoxide electroreduction possesses practical and strong antibacterial activity.

[0118] Test Example 7 Formalin reaction.

[0119] Test method: The electrolyte from carbon monoxide electroreduction was not purified after synthesis to retain the natural catalytic intermediate. The experimental procedure was as follows: 30 mL of carbon monoxide electroreduction electrolyte containing 1 mM glycolaldehyde and 15 mg calcium hydroxide was added to a 50 mL reactor, and the mixture was heated at 75 °C with controlled stirring for 75 min. For glycoderivatization, benzylation was carried out by sequentially adding sodium hydroxide / potassium carbonate (1:4, m / m), tetrabutylammonium bisulfate, benzyl chloride, and dimethyl sulfoxide (DMSO) to the aqueous product mixture. The reaction was vigorously stirred at room temperature for 12 h to ensure complete functionalization. The benzylated derivative was extracted with ethyl acetate, and its molecular identity was confirmed by electrospray ionization mass spectrometry (ESI-MS).

[0120] Test results are as follows Figure 16 (e) Figure 18 As shown.

[0121] Figure 16 (e) shows the synthesis of carbohydrate compounds from formaldehyde obtained by the electroreduction of carbon monoxide.

[0122] Figure 18 The mass spectrum of the electrocatalytic product after benzylation is shown. The resulting sugars (such as glucose) are benzylated to allow for separation from the salt matrix after the formalin reaction.

[0123] This invention utilizes an electrolyte containing 500 ppm formaldehyde generated by the electroreduction of carbon monoxide, and further investigates sugar synthesis via a formalin reaction (see...). Figure 16 (e)). The product 1 ¹H NMR contrast analysis revealed the presence of characteristic proton signals of carbohydrates (δ = 3.5–5 ppm), which were not detected in the control experiment without carbon monoxide electroreduction. Furthermore, benzyl derivatization electrospray ionization mass spectrometry (ESI-MS) confirmed the molecular identity of the sugar product (see [link to study]. Figure 18 ).

[0124] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0125] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

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Claims

1. A method for electrocatalytic high-efficiency synthesis of formaldehyde from carbon monoxide, characterized in that, Includes the following steps: S1. Carbon nanotubes and cobalt phthalocyanine molecular materials are dispersed in solvent 1 to obtain carbon nanotube suspension and cobalt phthalocyanine molecular material suspension respectively; the carbon nanotube suspension and cobalt phthalocyanine molecular material suspension are blended, ultrasonically treated, and stirred to obtain crude product; the crude product is purified and dried to obtain cobalt phthalocyanine-based molecularly dispersed electrocatalyst. S2. The cobalt phthalocyanine-based molecularly dispersed electrocatalyst and the ionic polymer are dispersed in solvent 2 and then coated onto carbon paper to obtain a cobalt phthalocyanine-based molecularly dispersed electrocatalyst electrode. S3. The phthalocyanine cobalt-based molecularly dispersed electrocatalyst electrode is installed in an electrolytic cell, and carbon monoxide is introduced to carry out an electrocatalytic reaction to obtain formaldehyde; in, The gas pressure of the carbon monoxide is 5-120 bar.

2. The method of claim 1, wherein the electrocatalytic conversion of carbon monoxide to formaldehyde is carried out at a current density of 10 mA / cm2 to 100 mA / cm2. In step S1, the cobalt phthalocyanine molecular material is selected from one or more of cobalt phthalocyanine or cobalt phthalocyanine derivatives.

3. The method of claim 2, wherein the electrocatalytic conversion of carbon monoxide to formaldehyde is carried out at a current density of 10 mA / cm2 to 100 mA / cm2. The cobalt phthalocyanine derivatives include electron-withdrawing cobalt phthalocyanine and electron-donating cobalt phthalocyanine.

4. The method of claim 3, wherein the electrocatalytic conversion of carbon monoxide to formaldehyde is carried out at a current density of 10 mA / cm2 to 100 mA / cm2. The electron-withdrawing group of the cobalt phthalocyanine is selected from one or more of cyano, -Cl, -F or -NO2; the electron-donating group of the cobalt phthalocyanine is selected from one or more of methoxy, -OH, -NH2 or -Me.

5. The method of claim 1, wherein the electrocatalytic conversion of carbon monoxide to formaldehyde is carried out at a current density of 10 mA / cm2 to 100 mA / cm2. In step S1, the mass ratio of the carbon nanotubes to the cobalt phthalocyanine molecular material is (6-100):

1.

6. The method of claim 1, wherein the electrocatalytic conversion of carbon monoxide to formaldehyde is carried out at a current density of 10 mA / cm2 to 100 mA / cm2. In step S2, the mass ratio of the cobalt phthalocyanine-based molecularly dispersed electrocatalyst to the ionic polymer is 1:(0.01-1).

7. The method of claim 1, wherein the electrocatalytic conversion of carbon monoxide to formaldehyde is carried out at a current density of 10 mA / cm2 to 100 mA / cm2. In step S1, solvent 1 is selected from one or more of N,N-dimethylformamide or dimethyl sulfoxide.

8. The method of claim 1, wherein the electrocatalytic conversion of carbon monoxide to formaldehyde is carried out with high efficiency. In step S2, the solvent 2 is selected from one or more of methanol or ethanol.

9. The method for efficient electrocatalytic synthesis of formaldehyde from carbon monoxide according to claim 1, characterized in that, The amount of the phthalocyanine cobalt-based molecularly dispersed electrocatalyst supported on the carbon paper in step S2 is 0.1-2 mg-cm -2 .

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