CN116575063A

CN116575063A - Electrode material, electrolysis device and application thereof

Info

Publication number: CN116575063A
Application number: CN202310598068.3A
Authority: CN
Inventors: 李宇; 叶子贤; 鲁统部
Original assignee: Tianjin University of Technology
Current assignee: Tianjin University of Technology
Priority date: 2023-05-24
Filing date: 2023-05-24
Publication date: 2023-08-11

Abstract

The invention discloses an electrode material, an electrolysis device and application thereof. The electrode material comprises a substrate and bismuth nano-sheets grown on the substrate in situ, and is prepared by pretreating a substrate made of metal, loading bismuth by a soaking method, calcining, performing electrochemical reduction, performing electrochemical reconstruction and the like. Moreover, the electrode material has the advantages of strong preparation controllability, high carbon dioxide reduction activity, good selectivity, good stability, capability of being connected with other electrodes to prepare products with high added value, and the like. Meanwhile, the invention also discloses a coupling method of carbon dioxide reduction and HMF oxidation, which is characterized in that a conductive substrate material loaded with nickel cobaltate is used as an anode, a metal substrate of bismuth nanosheets grown on the substrate in situ is used as a cathode, an electrolytic reaction system is assembled for electrolysis, and the selective oxidation of 5-hydroxymethylfurfural into 2, 5-furandicarboxylic acid can be realized at the anode, and the selective reduction of carbon dioxide into formic acid can be realized at the cathode.

Description

Electrode material, electrolysis device and application thereof

Technical Field

The invention relates to the technical field of electrodes, electrolysis and resource recycling, in particular to an electrode material, an electrolysis device and application thereof.

Background

Powering CO from renewable energy sources (e.g., wind and solar energy) ₂ The electrochemical conversion into value-added chemicals and fuels has wide application prospect. To enhance electrocatalytic CO ₂ In general, nanoparticles of noble metals or transition metals are used as catalytically active components and are supported on a carrier having a large specific surface area by means of an adhesive. However, these catalysts have problems such as loss of active sites of the catalytically active component due to the adhesive, poor stability of nanoparticle structure, and poor selectivity. Clearly, the electrocatalytic reduction of CO has been developed to date ₂ The catalysts and the complete electrolysis systems of (a) are limited by lower catalytic performance, poor structural stability and lower energy conversion efficiency and still cannot be operated on an industrial scale.

The oxidation product of 5-Hydroxymethylfurfural (HMF), 2, 5-furandicarboxylic acid (FDCA), is a feedstock for the preparation of the biopolymer polyethylene furanisoparaffinate (PEF), so 2, 5-furandicarboxylic acid is considered one of the most valuable chemicals. However, the production is mainly carried out by a catalytic oxidation process at present, and the problems of low utilization rate of resources and energy consumption exist. In order to enable the production and conversion process of high-value chemical products to meet the higher requirements of green economy and chemistry, a green, environment-friendly, economical and resource utilization-efficient process for producing 2, 5-furandicarboxylic acid is required.

Therefore, the invention not only needs to develop a catalyst with strong preparation controllability, high activity, good selectivity and good stability, but also is suitable for catalyzing CO ₂ There is also a need for developing an apparatus and method capable of comprehensively utilizing carbon dioxide, 5-hydroxymethylfurfural and electric energy for electrode materials for reduction reactions.

Disclosure of Invention

In order to overcome the problems of the prior art, the invention aims to provide an electrode material, an electrolysis device and application thereof.

In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:

in a first aspect, the present invention provides an electrode material comprising a substrate and bismuth nanoplatelets grown in situ on the substrate.

Preferably, the substrate is at least one selected from foam nickel, foam copper, nickel flakes and copper flakes.

Preferably, the sheet diameter of the bismuth nanosheets is 200-600 nm.

Further preferably, the bismuth nanosheets have a sheet diameter of 300 to 500nm.

Preferably, the thickness of the bismuth nanosheets is 1-3 nm.

In a second aspect, the present invention provides a method for preparing the electrode material according to the first aspect, comprising the steps of:

1) Pretreating a substrate, and then soaking the substrate in an acidic bismuth salt solution to obtain a bismuth-loaded substrate;

2) Calcining the substrate loaded with bismuth in the step 1) in an oxidizing atmosphere to obtain a substrate loaded with bismuth oxide;

3) And (3) carrying out electrochemical reduction and electrochemical reconstruction on the substrate carrying bismuth oxide in the step (2) to obtain the electrode material in the first aspect.

Preferably, the substrate in the step 1) is at least one selected from foam nickel, foam copper, nickel sheets and copper sheets.

Preferably, the preprocessing in step 1) includes: cutting a substrate, removing oil by using an organic solvent, and removing an oxide layer by using an acid washing liquid to obtain the pretreated foamy copper.

Preferably, the specific operation of removing the oxide layer by using the pickling solution is as follows: soaking the substrate in pickling solution, and carrying out ultrasonic treatment for 20-40 min.

Preferably, the organic solvent is at least one selected from acetone, acetonitrile, ethanol, methanol, ethylene glycol and glycerol.

Preferably, the acid is at least one selected from hydrochloric acid, nitric acid and sulfuric acid.

Preferably, the concentration of the acid in the pickling solution is 0.1-3 mol/L.

Preferably, the method for preparing the acidic bismuth salt solution in the step 1) is as follows:

the soluble bismuth salt, acid, water and organic solvent are mixed to prepare an acidic bismuth salt solution.

Preferably, the concentration of the soluble bismuth salt in the acidic bismuth salt solution is 0.01-0.5 mol/L based on the final concentration; the concentration of the acid in the acidic bismuth salt solution is 0.1-3 mol/L.

Preferably, the soluble bismuth salt is at least one selected from bismuth nitrate and bismuth nitrate hydrate.

Preferably, the bismuth nanosheets on the bismuth loaded substrate of step 1) have a sheet diameter of 100 to 300nm.

Preferably, the bismuth nanoplatelets on the bismuth-loaded substrate of step 1) have a thickness of 8 to 10nm.

Preferably, the soaking time in the step 1) is 10-30 s.

Preferably, the soaking temperature in the step 1) is 20-25 ℃.

Preferably, the oxidizing atmosphere in step 2) is one selected from oxygen and air.

Preferably, the calcination in step 2) takes 10 to 16 hours.

Further preferably, the calcination in step 2) takes about 12 hours.

Preferably, the calcination temperature in step 2) is 180 ℃ to 230 ℃.

Preferably, the heating rate of the calcination in the step 2) is 1-3 ℃ for min ^–1 。

Preferably, the electrochemical reduction and electrochemical reconstruction process in step 3) includes the following steps:

s1: the substrate loaded with bismuth oxide in the step 2) is used as a working electrode, an Ag/AgCl electrode is used as a reference electrode, a Pt electrode 1 is used as a counter electrode and an electrolyte to construct an electrolytic system, and the electrolytic system is electrolyzed for 3 to 5 hours under the potential of-1.50V vs. Ag/AgCl to-1.20V vs. Ag/AgCl and is used for reducing the bismuth oxide on the substrate loaded with bismuth oxide into metallic bismuth;

s2: changing a new electrolyte, and electrolyzing for 0.5 to 1.5 hours at the potential of-1.55V vs. Ag/AgCl to-1.65V vs. Ag/AgCl for reconstructing the metallic bismuth nano-sheet on the substrate to obtain an electrode material;

wherein in S1 and S2, the electrolyte is selected from CO ₂ Saturated KHCO ₃ Solution, K ₂ CO ₃ Solution of NaHCO ₃ Solution, na ₂ CO ₃ At least one of the solutions, and the solute concentration in the electrolyte is 0.1-1.0 mol/L. Specifically, the solute is KHCO ₃ 、K ₂ CO ₃ Solution of NaHCO ₃ 、Na ₂ CO ₃ At least one of them.

Preferably, in S1, an electrolysis system is constructed, firstly, electrolysis is carried out for 0.2 to 1 hour under the potential of-1.50V vs. Ag/AgCl to-1.40V vs. Ag/AgCl, and then electrolysis is carried out for 3 to 5 hours under the potential of-1.50V vs. Ag/AgCl to-1.40V vs. Ag/AgCl, so that bismuth oxide on a substrate loaded with bismuth oxide is reduced into metallic bismuth.

In a third aspect, the invention provides a coupling method of carbon dioxide reduction and 5-hydroxymethylfurfural oxidation, comprising the steps of:

the electrode material according to the first or second aspect is used as a cathode to support NiCo ₂ O ₄ Taking the conductive substrate material of (2) as an anode, taking a 5-hydroxymethylfurfural solution as an anode electrolyte, and taking a carbonate solution saturated by carbon dioxide as a cathode electrolyte; the electrolyte reaction system is assembled for electrolysis, 5-hydroxymethylfurfural is oxidized into 2, 5-furandicarboxylic acid at the anode, and carbon dioxide is reduced into formic acid at the cathode.

Preferably, the coupling method of carbon dioxide reduction and 5-hydroxymethylfurfural oxidation further comprises: separating the anolyte and the catholyte by a proton exchange membrane; and carbon dioxide is introduced into the catholyte during electrolysis for providing the cathode with a reactant gas.

Preferably, the electrolysis is performed in a constant voltage mode, and the voltage is 1.5-4V.

Further preferably, the electrolysis is performed by a constant voltage, and the voltage is 1.5 to 3V.

Preferably, in the electrolysis process, the flow rate of carbon dioxide introduced into the cathode chamber is 15-30 mL/min.

Preferably, the load is NiCo ₂ O ₄ The preparation method of the conductive substrate material comprises the following steps:

1) Dissolving soluble nickel salt, soluble cobalt salt and urea in water to obtain nickel cobalt precursor solution;

2) Immersing the pretreated conductive substrate in nickel-cobalt precursor solution, and carrying out hydrothermal reaction and annealing to obtain the NiCo-loaded conductive substrate ₂ O ₄ Is provided.

Specifically, the synergistic effect of the self-supporting electrode substrate and the bimetallic base material can further improve the conductivity of the catalyst material, and simultaneously can enable the catalyst to expose more active sites, so that the catalytic performance of the catalyst is greatly improved.

Preferably, the soluble nickel salt in the step 1) is one or more of nickel nitrate, nickel nitrate hydrate, nickel chloride and nickel sulfate.

Preferably, the soluble cobalt salt in the step 1) is one or more of cobalt nitrate and cobalt nitrate hydrate.

Preferably, the mole ratio of the soluble nickel salt, the soluble cobalt salt and the urea in the step 1) is 1 (1-3): (4-6).

Preferably, the pretreatment in the pretreated conductive substrate in step 2) includes: oil removal, descaling, water washing and alcohol washing.

Preferably, the temperature of the hydrothermal reaction in the step 2) is 110-140 ℃.

Preferably, the hydrothermal reaction in the step 2) is carried out for 4-8 hours.

Preferably, the annealing in step 2) is performed in an air atmosphere or an oxygen atmosphere.

Preferably, the heating rate of the annealing in the step 2) is 1-3 ℃ for min ^–1 。

Preferably, the annealing temperature in the step 2) is 280-350 ℃, and the annealing time is 1-5 h.

Preferably, the cathode and the anode are immersed in a catholyte and an anolyte, respectively. Preferably, the volume ratio of the effective area of the cathode to the catholyte is (1-5) cm ² : (10-20) mL. Preferably, the volume ratio of the effective area of the anode to the anolyte is (1-5) cm ² ：(10～20)mL。

Preferably, the ratio of the effective areas of the cathode and the anode is 1: (0.8-1.2).

Preferably, the load is NiCo ₂ O ₄ The conductive substrate in the conductive substrate material is one or more of carbon cloth, carbon rod, foam nickel, foam copper, copper sheet and nickel sheet.

Preferably, the carbon dioxide saturated carbonate solution is selected from the group consisting of CO ₂ Saturated KHCO ₃ Solution, K ₂ CO ₃ Solution of NaHCO ₃ Solution, na ₂ CO ₃ At least one of the solutions, and the solute concentration in the electrolyte is 0.1-1.0 mol/L.

Preferably, the concentration of 5-hydroxymethylfurfural in the 5-hydroxymethylfurfural solution is 5-20 mmol/L.

Preferably, the 5-hydroxymethylfurfural solution further comprises 0.5-3 mol/L of alkali, and the alkali is at least one selected from sodium hydroxide and potassium hydroxide.

Further preferred, the 5-hydroxymethylfurfural solution consists of 5-hydroxymethylfurfural and the base.

In a fourth aspect, the invention provides the use of the method of the third aspect in the production of 2, 5-furandicarboxylic acid or the integrated use of carbon dioxide.

In a fifth aspect, the present invention provides an electrolysis device comprising an electrode material according to the first aspect or an electrode material produced according to the second aspect.

Preferably, the electrolysis apparatus comprises: cathode, anode, container, diaphragm, wire, power supply and air vent;

the cathode is the electrode material of the first or second aspect, and the anode is NiCo-loaded ₂ O ₄ The anode electrolyte is 5-hydroxymethyl furfural solution, and the cathode electrolyte is carbonate solution saturated by carbon dioxide;

wherein the membrane separates the container into a cathode chamber and an anode chamber; the cathode, the power supply and the anode are connected in sequence by leads.

Preferably, the vent is provided in the cathode chamber for supplying carbon dioxide feed gas to the electrolysis device.

Preferably, the cathode and the anode are respectively immersed in a catholyte and an anolyte, and the effective area of the cathode and the anode is 1-5 cm ² 。

Preferably, the power supply is one of a direct current power supply and an alternating current power supply.

Preferably, the power supply is a power supply capable of supplying a voltage of 1.1V to 5V.

Further preferably, the power supply is a power supply capable of supplying a voltage of 1.5V to 4V.

Preferably, the temperature of the hydrothermal reaction in the step 2) is 110-140 ℃. Preferably, the hydrothermal reaction in the step 2) is carried out for 4-8 hours.

Preferably, the membrane is a proton exchange membrane. Further preferably, the membrane is a Nafion 117 type proton exchange membrane.

Preferably, the volume of the catholyte is no more than two-thirds of the volume of the cathode chamber.

Preferably, the volume of the anolyte is no more than two-thirds of the volume of the anode chamber.

The beneficial effects of the invention are as follows: the electrode material comprises a substrate and bismuth nano-sheets grown on the substrate in situ, and is prepared by pretreating a substrate made of metal, loading bismuth by a soaking method, calcining, performing electrochemical reduction, performing electrochemical reconstruction and the like. Moreover, the electrode material has the advantages of strong preparation controllability, high carbon dioxide reduction activity, good selectivity, good stability, capability of being connected with other electrodes to prepare products with high added value, and the like. The method comprises the following steps:

(1) The electrode material does not need an adhesive, has the advantages of good environment protection, stable structure and strong preparation controllability, and is suitable for large-scale preparation and practical application.

(2) Aiming at the anodic HMF oxidation reaction, the invention prepares the sea urchin-shaped NiCo which grows on the surface of the foam nickel in situ ₂ O ₄ Catalyst (NiCo) ₂ O ₄ @ NF) is capable of efficiently oxidizing HMF to FDCA. For cathode CO ₂ The Bi-based catalyst prepared by the method has higher selectivity and activity to formate, and the nano-sheet on the Bi catalyst has good structure stability effect, thus being suitable for electrocatalytic CO ₂ And (5) reduction.

(3) The coupling method of HMF oxidation and carbon dioxide reduction is to use a NiCo spinel oxide catalyst (NiCo ₂ O ₄ @NF) is used as an anode, the electrode material (namely Bi NSs@CF electrode) is used as a cathode, an electrolytic reaction system is assembled for electrolysis, 5-hydroxymethylfurfural is selectively oxidized into 2, 5-furandicarboxylic acid at the anode, and carbon dioxide is selectively reduced into formic acid at the cathode; wherein the anolyte is alkaline solution containing 10mM HMF, and the catholyte isAnd an ion exchange membrane is arranged between the anolyte and the catholyte in the electrolysis reaction system.

(4) The electrolytic device and the coupling method can realize CO ₂ The comprehensive utilization of HMF and electric energy can improve the comprehensive utilization rate of resources (including raw materials and energy sources) and can produce the 2, 5-furandicarboxylic acid product with high added value under the condition of low concentration of reactants.

(5) The electrolytic device or the coupling method can reach higher Faraday efficiency and yield of the target product at the same time at the cathode and the anode under the condition of lower cell voltage.

Drawings

FIG. 1 is a schematic diagram of CO in the present invention ₂ Schematic structural diagram of an electrolyzer for reduction and HMF oxidative coupling.

FIG. 2 is NiCo in example 1 ₂ O ₄ @NF and Co in comparative example 1 ₃ O ₄ XRD pattern of @ NF.

FIG. 3 is NiCo in example 1 ₂ O ₄ SEM image of @ NF.

FIG. 4 is Co of comparative example 1 ₃ O ₄ SEM image of @ NF.

FIG. 5 is NiCo in example 1 ₂ O ₄ @NF and Co in comparative example 1 ₃ O ₄ LSV plot @ NF.

FIG. 6 is NiCo of example 1 ₂ O ₄ @NF and Co in comparative example 1 ₃ O ₄ Comparative graphs of FDCA yield and FDCA faraday efficiency at different voltages @ NF.

FIG. 7 is an XRD pattern for Bi NSs@CF in example 2.

Fig. 8 is an SEM image of bi@cf in example 2.

Fig. 9 is SEM and HRTEM images of Bi nss@cf in example 2.

FIG. 10 is a LSV plot of Bi NSs@CF and Bi@CF in example 2.

FIG. 11 is a graph of Faraday efficiency of the formate salts of Bi NSs@CF and Bi@CF in example 2.

FIG. 12 is a schematic diagram of example 3NiCo of (C) ₂ O ₄ LSV graph of @ NF @ Bi NSs @ CF two electrode catalytic system.

FIG. 13 is NiCo in example 3 ₂ O ₄ HCOO in two-electrode catalytic system of @ NF Bi NSs @ CF ^– Results of the tests of faraday efficiency of FDCA, faraday efficiency of FDCA and yield of FDCA.

Detailed Description

The present invention will be described in further detail with reference to specific examples. The "effective area" in the present invention refers to the contact area of the electrode material with the electrolyte on a macroscopic scale, unless otherwise specified.

Example 1

The present embodiment provides an anode material (NiCo ₂ O ₄ @nf) comprising the steps of:

(1) Pretreatment of foam nickel: first, a block of 2X 3cm is put ² Cleaning the foam nickel with acetone to remove greasy dirt on the surface of the foam nickel and obtain the foam nickel after oil removal;

then transferring the deoiled foam nickel into 1.0M HCl solution, performing ultrasonic treatment for 30 minutes, and then flushing with water and ethanol to obtain pretreated foam nickel;

(2) Sea urchin-like NiCo ₂ O ₄ Preparation of @ NF: 1.0mmol Ni (NO) ₃ ) ₂ ·6H ₂ O，2.0mmol Co(NO ₃ ) ₂ ·6H ₂ O and 5.0mmol urea are dissolved in 35ml ultra-pure water, and then stirred for 20min to obtain nickel cobalt precursor solution;

transferring the nickel-cobalt precursor solution into a high-pressure reaction kettle with the capacity volume of 50mL, and then placing the treated foam nickel into the high-pressure reaction kettle, and ensuring to be soaked in the nickel-cobalt precursor solution;

placing the reaction kettle in an oven, setting at 393K (about 120 ℃) for reaction for 6 hours, naturally cooling to room temperature, and then washing with distilled water and ethanol for precipitation for several times to remove residual metal salt on the surface of the foam nickel;

drying the precipitate at 333K (about 60 deg.C) for 12 hr, and air-drying for 2K min ^–1 (2℃min ^–1 ) The temperature rise rate of (C) was increased to 573K (about 300 ℃ C.), and annealing was performed for 3 hours to obtain an anode material (referred to as NiCo) ₂ O ₄ @ NF, morphology: sea urchin-like).

Comparative example 1

The present embodiment provides an anode material (Co ₃ O ₄ @nf) comprising the steps of:

then, the foam nickel after degreasing is transferred into 1.0M HCl solution, and after ultrasonic treatment for 30 minutes, the foam nickel after pretreatment is obtained by washing with water and ethanol.

(2)Co ₃ O ₄ Preparation of @ NF: 3.0mmol Co (NO) ₃ ) ₂ ·6H ₂ O and 5.0mmol urea are dissolved in 35ml ultra-pure water, and then stirred for 20min to obtain nickel cobalt precursor solution;

drying the precipitate at 333K (about 60 deg.C) for 12 hr, and air-drying for 2K min ^–1 (2℃min ^–1 ) The temperature rise rate of (C) was increased to 573K (about 300 ℃ C.), and annealing was performed for 3 hours to obtain an anode material (denoted as Co) ₃ O ₄ @NF)。

Characterization and performance testing of anode materials:

1. NiCo in example 1 ₂ O ₄ @NF and Co in comparative example 1 ₃ O ₄ An X-ray diffraction (XRD) pattern of @ NF, as shown in fig. 2.

As can be seen from fig. 2: as can be seen from the figure, niCo was prepared ₂ O ₄ At @ NF2 theta = 31.1 °,36.7 °,44.6 °,59.1 ° and 65.0 ° XRD diffraction peaks, co prepared ₃ O ₄ Obvious XRD diffraction peaks at 2θ=31.3°,36.9 °,44.8 °,59.4 ° and 65.2 ° for the @ NF electrode correspond to NiCo, respectively ₂ O ₄ (PDF # 20-0781) and Co ₃ O ₄ (PDF # 42-1467) illustrating the successful in situ loading of NiCo on a nickel foam material by hydrothermal method in example 1 and comparative example 1, respectively ₂ O ₄ And Co ₃ O ₄ 。

2. NiCo in example 1 ₂ O ₄ Scanning electron microscope (Scanning Electron Microscope, SEM) image of @ NF, as shown in fig. 3. Co in comparative example 1 ₃ O ₄ SEM image of @ NF, as shown in fig. 4.

As can be seen from fig. 3 and 4: from NiCo ₂ O ₄ In SEM pictures of NF it can be seen that example 1 is able to be calcined by hydrothermal reaction and high temperature, the surface of the nickel foam is covered with a dense nano sea urchin structure, which is mainly assembled from nanofibers of relatively uniform size resembling petals. This demonstrates that example 1 successfully produced NiCo with three-dimensional nano sea urchin structure ₂ O ₄ @nf electrode material.

By further amplification and analysis, the sea urchin structure NiCo of example 1 ₂ O ₄ The @ NF electrode material is made of NiCO having a diameter and length of about 50nm and 960nm ₂ O ₄ The nanoneedle is assembled. Furthermore, in example 1, a large amount of NiCo was produced on the surface of nickel foam ₂ O ₄ The nanoneedle is epitaxially grown from the center to form a sea urchin shape, and the unique structure thereof enables NiCo to be formed ₂ O ₄ Has larger specific surface area, is beneficial to exposing more active sites so as to improve the activity of the catalyst.

From Co ₃ O ₄ In SEM pictures of @ NF electrodes, co grown in situ on nickel foam of comparative example 1 was observed ₃ O ₄ Is formed by mixing and growing nano sheets with larger sheet diameters and nano needles, and the arrangement of the nano structures is disordered.

3.

Test sample: in example 1NiCo ₂ O ₄ @ NF, co in comparative example 1 ₃ O ₄ @NF

The electrocatalytic HMF oxidation test method for single electrode (anode) is as follows:

the electrochemical tests of the experiment are all carried out under the conditions of room temperature (20-25 ℃) and normal pressure (100-102 kPa) by using a CHI 760e electrochemical workstation.

(1) The H-type electrolytic cell was divided into two parts using an anion exchange membrane (FAA-PK-130); the cathode chamber and the anode chamber are filled with 16mL of 1.0M KOH solution, and the effective area is 1X 1cm ² Directly as working electrode, pt plate electrode (1X 1 cm) ² ) And an Ag/AgCl electrode (3M saturated KCl solution) were used as a counter electrode and a reference electrode, respectively, to construct a three-electrode system.

(2) Faraday efficiency and yield test of FDCA: in the electrochemical HMF oxidation test, a certain amount of HMF was added to the anolyte so that the initial concentration of HMF of the anolyte was 10mM, and the performance of electrochemical HMF oxidation was tested in different constant voltage modes.

Meanwhile, quantitative analysis is carried out on HMF and products thereof by using an island body High Performance Liquid Chromatograph (HPLC) provided with a detector with lambda=265 nm and a C18 column; wherein, HPLC mobile phase setting parameters are: 5mM ammonium formate aqueous solution and methanol, the volume ratio of the two is 7:3, flow rate of 0.5 mL min ^–1 Column temperature is 40 ℃; the quantitative and qualitative analyses are based on external standard calibration curves of known concentrations of pure components.

The FDCA yield and FDCA faraday efficiency were measured by testing and analysis, as shown in fig. 6.

Testing of LSV curve: the three-electrode system in (1) was tested with 1.0V-1.6V and scanning rate of 5mV/s to obtain NiCo in different cases by using 1.0M KOH solution without HMF (denoted OER) or 1.0M KOH solution containing 10mM HMF (5-hydroxymethylfurfural) (denoted HMFOER) as anolyte ₂ O ₄ @NF and Co ₃ O ₄ The LSV curve at NF and the results are shown in FIG. 5.

Test results:

NiCo ₂ O ₄ @NF and Co ₃ O ₄ The LSV plot for NF is shown in fig. 5.

As can be seen from fig. 5: it is evident from fig. 5 that the catalyst activity was low without HMF and the OER reaction initiation potential was greater than 1.45V. The potential of the same test sample (catalyst) at the same current density was significantly reduced after HMF addition compared to OER group. Moreover, the test results demonstrate that under the test conditions of HMFOR, niCo ₂ O ₄ The electrooxidative activity of @ NF was higher than Co ₃ O ₄ @NF。

NiCo ₂ O ₄ @NF and Co ₃ O ₄ Comparative plots of FDCA yield and FDCA faraday efficiency at different voltages for @ NF, as shown in fig. 6; wherein, the bar graph shows the change of FDCA Faraday efficiency under different voltages, and the graph shows the change of FDCA yield under different voltages.

As can be seen from fig. 6: FIG. 6 records NiCo ₂ O ₄ @NF and Co ₃ O ₄ Variation in faradaic efficiency and yield of FDCA in the range of 1.25 to 1.50vvs.rhe when HMFOR was performed by @ NF.

NiCo ₂ O ₄ The @ NF is in the potential range of 1.30V to 1.35V, and the Faraday efficiency and yield of the FDCA are both above 90 percent. At 1.35V, FDCA Faraday efficiency and yield were 97.3%, co ₃ O ₄ FDCA Faraday efficiency and yield at 1.40V for @ NF was highest at 94.8% and 87.8%, respectively.

However, with increasing potential, the competing effects of the Oxygen Evolution Reaction (OER) of water become increasingly apparent. NiCo ₂ O ₄ FDCA faraday efficiency and yield of @ NF gradually decrease; at 1.50V, FDCA faraday efficiency was less than 70% and FDCA yield was less than 80%.

These results clearly demonstrate that: 1.35V is NiCo ₂ O ₄ The @ NF catalyzes the optimal potential for HMF oxidation.

Example 2

The embodiment provides a preparation method of a cathode material (Bi NSs@CF), which comprises the following steps:

(1) Pretreatment of foam copper: first, a block of 1X 3cm is put ² Is a bulb of (2)Washing foam copper with acetone to remove greasy dirt on the surface of the foam copper and obtain deoiled foam copper;

then, the deoiled copper foam is transferred into 1.0M HCl solution, and after ultrasonic treatment for 30 minutes, the pretreated copper foam is obtained by washing with water and ethanol.

(2) Preparation of Bi@CF: immersing the pretreated copper foam in a solution containing 0.1M Bi (NO ₃ ) ₃ And 1.0M HNO ₃ In the bismuth salt solution (the solvent consists of water and acetonitrile, and the volume ratio of the water to the acetonitrile is 1:1), the color of the foam copper is changed from reddish brown to light gray immediately, after soaking for 20 seconds, the foam copper is taken out of the solution, washed by water and ethanol, and dried by nitrogen to obtain the foam copper loaded with bismuth (marked as Bi@CF).

(3)Bi ₂ O ₃ Preparation of @ CF: placing Bi@CF in a tube furnace for 2K min ^–1 (2℃min ^–1 ) The temperature rise rate of (2) was increased to 473K (about 200 ℃) and calcination was controlled under an air atmosphere for 12 hours, and after natural cooling to room temperature, bismuth oxide-supported copper foam (noted as Bi) was obtained ₂ O ₃ @ CF, color: yellow).

(4) Preparation of Bi NSs@CF: bi NSs@CF is derived from Bi ₂ O ₃ The @ CF was formed by electrochemical reduction and in situ reconstitution.

Bi is used as ₂ O ₃ The @ CF is a working electrode, the Ag/AgCl electrode is a reference electrode, and the Pt sheet is a counter electrode; in CO ₂ Saturated 0.5M KHCO ₃ Is electrolyzed at a potential of-1.45V vs. Ag/AgCl for 0.5 hours, and then at a potential of-1.25V vs. Ag/AgCl for 4 hours, bi is electrolyzed ₂ O ₃ Preliminary reduction in @ CF to Bi;

subsequently, the new electrolyte (i.e. 0.5M KHCO) ₃ Solution of (c), introducing CO ₂ After saturation, electrolysis was further carried out for 1 hour at a potential of-1.6V vs. Ag/AgCl to give a cathode material (noted Bi NSs@CF);

the cathode material was tested and analyzed to be Bi nss@cf with stable nanoplatelet structure.

Characterization and performance testing of cathode materials:

1. XRD patterns of Bi NSs@CF in example 2 are shown in FIG. 7.

As can be seen from fig. 7: the XRD spectrum of Bi nss@cf in example 2 showed diffraction peaks at 2θ=27.3°, 38.1 °, 39.7 °, 48.9 ° and 56.3 °, which are coincident with the (012), (104), (110), (202) and (024) crystal planes in standard card pdf#85-1331 of Bi, demonstrating that the material on the copper foam is metallic Bi.

2. SEM images of bi@cf in example 2 are shown in fig. 8. SEM images of Bi nss@cf and high-resolution transmission electron microscope (High Resolution Transmission Electron Microscope, HRTEM) images in example 2 are shown in (a) and (b) of fig. 9, respectively.

As can be seen from fig. 8 and 9: fig. 8 shows SEM images of bi@cf, from which it can be observed that irregular Bi nanoplatelets grow closely on the surface of copper foam, and that the Bi nanoplatelets in bi@cf have a sheet diameter of about 100 to 300nm and a thickness of about 8 to 10nm. Although the Bi@CF prepared by preliminary reduction has a nano-platelet structure, bi on the Bi@CF prepared by preliminary reduction is used for electrocatalytic CO ₂ In-situ reconstruction occurs in the reduction process, and the structural stability of the material is poor, which is unfavorable for practical application.

In order to prepare the Bi-based catalyst (Bi NSs@CF) with the stable nano-sheet structure, the Bi@CF needs to be oxidized into Bi in the preparation process of the Bi NSs@CF ₂ O ₃ And (3) reducing the nano-sheet structure Bi NSs@CF under the electrochemical reduction condition. After the electrochemical preliminary reduction, the CO needs to be replaced ₂ Saturated KHCO ₃ And electrolyzed at a potential of-1.6 v vs. ag/AgCl (i.e., carbon dioxide reduction potential) for one hour, thereby enabling the formation of stable Bi nanoplatelet morphology on copper foam, which is biased toward vertical growth (see fig. 9).

Fig. 9 (a) shows an SEM image of Bi nss@cf, from which it can be observed that a plurality of fan-shaped Bi nanoplatelets grow in groups on the surface of copper foam, with a sheet diameter of about 400nm and a thickness of about 2nm. Under the reaction condition, the morphology of the Bi nano-sheets is changed only through reconstruction, and the Bi nano-sheets which have larger sheet diameter size, are more stable and are more suitable for carbon dioxide reduction are formed. Fig. 9 (b) shows the HRTEM image display of Bi nss@cf: the nano-sheets on the Bi NSs@CF are self-assembled from particles having a particle size of about 5 nm.

As the Bi nano-sheets on the Bi NSs@CF have thinner thickness and larger sheet diameter, and pores are arranged among particles, the specific surface area is favorably improved, the exposure number of active reaction sites is increased, the mass transfer is promoted, the electron transfer efficiency is improved, and the catalytic performance of the cathode is further improved. In addition, generally, the potential energy of the nano particles is larger, the structural stability is poorer, however, the Bi nano sheet assembled by the nano particles on the Bi NSs@CF has better stability in the carbon dioxide reduction process, and is suitable for practical popularization and application.

3. Test sample: bi NSs@CF and Bi@CF in example 2

The performance test method of the electrocatalytic reduction of carbon dioxide of the cathode (single electrode) is as follows:

CO in the present invention unless otherwise specified ₂ RR tests were all performed using a CHI 760e electrochemical workstation at room temperature (20-25 ℃) and normal pressure (100-102 kPa).

The sealed H-cell in this experiment was divided into two parts by a proton exchange membrane (Nafion 117).

(1) The test sample was used directly as a working electrode (effective area 1X 1cm ² ) Pt sheet electrode (1X 1 cm) ² ) And an Ag/AgCl electrode (3M saturated KCl solution) respectively serving as a counter electrode and a reference electrode, so as to construct a three-electrode system;

16mL of 0.5M KHCO was poured into both the cathode and anode chambers ₃ A solution; the volume of the cavity at the top of the electrolytic cell is controlled to be 16mL, and the electrolytic cell is used for buffering and facilitating the gas to enter and exit;

before the electrocatalytic carbon dioxide reduction test is carried out, high-purity CO is respectively introduced into the cathode chamber and the anode chamber ₂ The gas was saturated for 30 minutes.

(2) And (3) activating treatment: in the electrocatalytic carbon dioxide reduction test and the linear sweep voltammetry test, in order to avoid the electricity consumption of the catalyst due to the oxide formed by spontaneous oxidation in the air contained in the surface, the test sample is firstly subjected to activation treatment by a cyclic voltammetry method, and the activation conditions are as follows: scanning potential range of-0.6 to 0V vs. RHE, scanningAt a speed of 50mV s ^-1 The method comprises the steps of carrying out a first treatment on the surface of the Activation is completed when the cyclic voltammogram is close to coincidence.

(3) Faraday efficiency test of formate: after the activation was completed, in the linear sweep voltammetric test, the sweep rate was set to 5mV s ^-1 The method comprises the steps of carrying out a first treatment on the surface of the Subsequently, potentiostatic electrolysis was performed at various potentials, and after the electric quantity reached 5C, the electrolysis was stopped, and the liquid in the cathode chamber was collected, and quantitative analysis of formate was performed using an ion chromatograph equipped with an anion analysis column (Metrosep A support 5-150/4.0). The diluted electrolyte is manually injected by using a syringe by 4 to 5 milliliters, 10 mu L of the chromatographic automatic sampling enters an analysis column for detection, the diluted electrolyte is manually injected by using a syringe by 4 to 5 milliliters, 10 mu L of the chromatographic automatic sampling enters the analysis column for detection, and the calculated and analyzed results are shown in figure 11.

Testing of LSV curve: by Ar or CO ₂ Saturated 0.5M KHCO ₃ The solution was used as electrolyte and the three-electrode system of test method (1) was used, with a scan rate of 5mV s in the voltage range of-0.6 to-1.2V vs. RHE ^-1 The LSV curves of Bi NSs@CF and Bi@CF were measured, respectively.

Test results:

the LSV curves for Bi NSs@CF and Bi@CF are shown in FIG. 10.

As can be seen from fig. 10: it can be seen from FIG. 10 that the current density of Bi NSs@CF is greater than that of Bi@CF over the voltage range of-0.6 to-1.2V vs. RHE. In Ar saturated electrolyte, the current density of Bi NSs@CF was 9.7mA cm at a voltage of-0.75V vs. RHE ^–2 The method comprises the steps of carrying out a first treatment on the surface of the In CO ₂ In saturated electrolyte, bi NSs@CF can achieve 34.2mA cm at this potential ^–2 While the current density of Bi@CF is only 2.4mA cm ^–2 . The results illustrate: bi NSs@CF has a higher CO than Bi@CF ₂ RR activity.

To evaluate Bi NSs@CF and Bi@CF vs. CO ₂ RR product selectivity this experiment was performed using potentiostatic electrolysis in the voltage range-0.6 to-0.8 v vs. rhe. The faraday efficiencies of Bi nss@cf and bi@cf formate in example 2 are compared as shown in fig. 11.

As can be seen from fig. 11: at a potential of-0.75V vs. RHE, the Faraday efficiency of the formate was highest, reaching 94.1%. While the Faraday efficiency of the formate at this potential was 81.1% for Bi@CF.

This indicates that: bi NSs@CF is capable of more selectively converting CO than Bi@CF ₂ Reduced to formate.

Example 3

The present embodiment provides a CO ₂ The reduction and HMF oxidative coupling electrolysis apparatus (see fig. 1) is essentially an H-type cell comprising: niCo in example 1 ₂ O ₄ NF (cathode, active area: 1X 1 cm) ² ) Bi nss@cf in example 2 (anode, active area: 1X 1cm ² ) 1M KOH solution (anolyte) containing 10mM 5-Hydroxymethylfurfural (HMF), 0.5M KHCO saturated with carbon dioxide ₃ Solution (catholyte), container, nafion 117 type proton exchange membrane, wire, power supply, air vent;

a vessel consisting of 50mL of anode chamber and 50mL of cathode chamber, the anode chamber and anode chamber being separated by a Nafion 117 type proton exchange membrane;

NiCo in example 1 ₂ O ₄ The @ NF (cathode), bi nss @ cf (anode) of example 2 were immersed in the catholyte and anolyte, respectively, and the cathode, power supply and anode were connected by wires;

a vent is provided in the cathode chamber for providing a catholyte with a feed gas comprising carbon dioxide.

The power supply in the electrolytic device of this embodiment may be capable of supplying a voltage of 1.5 to 4V.

The electrolysis device is used for simultaneously realizing the processes of oxidizing 5-hydroxymethylfurfural into 2, 5-furandicarboxylic acid (FDCA) and reducing carbon dioxide into formic acid, and not only can produce FDCA with higher value, but also can realize the purposes of recycling and comprehensive utilization of carbon dioxide resources.

The embodiment also provides a CO ₂ A method of reduction and HMF oxidative coupling (see fig. 1), comprising the steps of:

(1) Construction of an electrolysis device: an H-type electrolytic cell is selected as an electrolytic device, a cathode chamber and an anode chamber of the electrolytic cell are separated by a Nafion 117 type proton exchange membrane, and the volumes of the cathode chamber and the anode chamber are 32mL;

16mL of 1M KOH solution containing 10mM HMF was poured into the anode chamber;

16mL of 0.5M KHCO was poured into the cathode chamber ₃ After the solution, 0.5M KHCO was introduced into the cathode chamber through the vent ₃ Continuously introducing carbon dioxide gas into the solution, and ensuring that air in the cathode chamber is discharged, wherein electrolyte in the cathode chamber is in a carbon dioxide saturated state (the ventilation time is 30 min);

with an effective area of 1X 1cm ² Bi NSs@CF of (1X 1 cm) as anode ² NiCo of (C) ₂ O ₄ The @ NF is used as a cathode; and sequentially connecting the cathode, the power supply and the anode by using leads to assemble NiCo ₂ O ₄ Two-electrode catalytic system of @ NF @ Bi NSs @ CF (see FIG. 1); thus, the electrolytic device of this example was constructed.

(2) Operation of the device: controlling the electrolyte in the cathode chamber to be 20mL min ^-1 Continuously introducing carbon dioxide gas into the flow of the catalyst, and simultaneously turning on a power supply to electrolyze the catalyst to realize the electric oxidation of the HMF of the 5-hydroxymethylfurfural and the electric catalysis of CO ₂ And (5) reduction.

And after the electric quantity is 87 ℃, quantitatively detecting the anode product by utilizing high performance liquid chromatography analysis, and quantitatively detecting the cathode product by utilizing gas chromatography and ion chromatography.

CO in the present invention ₂ The structure of the electrolytic device for reduction and HMF oxidative coupling is schematically shown in fig. 1.

As can be seen from fig. 1: the invention provides a CO ₂ A method of reduction and HMF oxidative coupling, which couples 2 electrocatalytic reaction processes. Specifically, it is a NiCo spinel oxide catalyst (NiCo ₂ O ₄ @NF) is used as an anode, a Bi NSs@CF electrode is used as a cathode, a double-electrode catalytic reaction system is assembled for electrolysis, selective oxidation of 5-hydroxymethylfurfural into 2, 5-furandicarboxylic acid is realized at the anode, and selective reduction of carbon dioxide into formic acid is realized at the cathode;

wherein the anolyte is a potassium hydroxide solution containing 5-hydroxymethylfurfural and the catholyte is a carbon dioxide saturated bicarbonate solution (e.g., potassium bicarbonate solution); an ion exchange membrane is arranged between the anolyte and the catholyte in the electrolytic reaction system.

Performance test:

using the electrolysis apparatus of example 3, and by merely varying the HMF content in the anolyte, niCo was performed when the anolyte contained HMF (10 mM) and did not contain HMF ₂ O ₄ The LSV curve test of the @ NF @ Bi NSs @ CF two-electrode catalyst system was used to evaluate the coupled HMF oxidation and carbon dioxide reduction reactions, the test results of which are shown in FIG. 12.

As can be seen from fig. 12: the cell pressure of the HMF-containing electrolyzer was significantly reduced and the current was significantly increased relative to the HMF-free electrolyzer. This demonstrates that the electrolyzer or process is capable of driving the HMF oxidation and carbon dioxide reduction reactions at a voltage of 1.25V, and NiCo ₂ O ₄ The two-electrode catalytic system of @ NF @ Bi NSs @ CF has better catalytic reaction activity.

Using the electrolyzer of example 3, niCo in example 3 ₂ O ₄ HCOO of @ NF Bi NSs @ CF two-electrode catalytic system in the cell voltage range of 1.5 to 2.1V ^– Faraday efficiency, FDCA faraday efficiency and yield of FDCA were tested as shown in fig. 13.

As can be seen from fig. 13: the Faraday efficiency of formate and FDCA increases and decreases with increasing cell pressure, and is highest at 1.9V, where the Faraday efficiency of FDCA in the electrooxidation reaction of HMF at the anode is 90.7% and the cathode CO ₂ The Faraday efficiency of formate in the electro-reduction reaction of (2) can also reach 85.1%, and the yield of FDCA can also reach 90%.

The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.

Claims

1. An electrode material, characterized in that it comprises a substrate and bismuth nanoplatelets grown in situ on the substrate.

2. The electrode material according to claim 1, wherein: the substrate is at least one selected from foam nickel, foam copper, nickel sheets and copper sheets; the sheet diameter of the bismuth nano sheet is 200-600 nm.

3. The method for producing an electrode material according to claim 1 or 2, characterized by comprising the steps of:

3) And (3) carrying out electrochemical reduction and electrochemical reconstruction on the substrate carrying bismuth oxide in the step (2) to obtain the electrode material.

4. The method for preparing an electrode material according to claim 3, wherein the electrochemical reduction and electrochemical reconstruction process in step 3) comprises the steps of:

s1: the substrate loaded with bismuth oxide in the step 2) is used as a working electrode, an Ag/AgCl electrode is used as a reference electrode, a Pt electrode 1 is used as a counter electrode and an electrolyte to construct an electrolytic system, and the electrolytic system is electrolyzed for 3 to 5 hours under the potential of-1.50V vs. Ag/AgCl to-1.20V vs. Ag/AgCl to obtain an electrochemically reduced material;

wherein in S1 and S2, the electrolyte is selected from CO ₂ Saturated KHCO ₃ Solution, K ₂ CO ₃ Solution of NaHCO ₃ Solution, na ₂ CO ₃ In solution toOne less, and the solute concentration in the electrolyte is 0.1-1.0 mol/L.

5. The method for producing an electrode material according to claim 3 or 4, comprising the steps of: step 2) the oxidizing atmosphere is selected from one of oxygen and air; the calcining temperature in the step 2) is 180-230 ℃; the calcination time in the step 2) is 10-16 h.

6. A coupling method of carbon dioxide reduction and 5-hydroxymethylfurfural oxidation, comprising the steps of:

an electrode material as a cathode, which is prepared by the method of any one of claims 3 to 5, and which is NiCo-supported ₂ O ₄ The conductive substrate material of (2) is used as an anode, a 5-hydroxymethylfurfural solution is used as an anolyte, a carbonate solution saturated by carbon dioxide is used as a catholyte, an electrolytic reaction system is assembled for electrolysis, the oxidation of 5-hydroxymethylfurfural into 2, 5-furandicarboxylic acid is realized at the anode, and the reduction of carbon dioxide into formic acid is realized at the cathode.

7. The coupling method of carbon dioxide reduction and 5-hydroxymethylfurfural oxidation according to claim 6, wherein: the said load is NiCo ₂ O ₄ The preparation method of the conductive substrate material comprises the following steps:

2) Immersing the pretreated conductive substrate in nickel-cobalt precursor solution, and carrying out hydrothermal reaction and annealing to obtain the NiCo-loaded conductive substrate ₂ O ₄ Is a conductive base material of (a);

wherein, the mole ratio of the soluble nickel salt, the soluble cobalt salt and the urea in the step 1) is 1 (1-3): (4-6);

the temperature of the hydrothermal reaction in the step 2) is 110-140 ℃; step 2) the annealing is performed in an air atmosphere or an oxygen atmosphere; the annealing temperature in the step 2) is 280-350 ℃.

8. The coupling method of carbon dioxide reduction and 5-hydroxymethylfurfural oxidation according to claim 6 or 7, characterized in that: the voltage adopted by the electrolysis is 1.5-4V; the carbon dioxide saturated carbonate solution is selected from CO ₂ Saturated KHCO ₃ Solution, K ₂ CO ₃ Solution of NaHCO ₃ Solution, na ₂ CO ₃ At least one of the solutions.

9. Use of the coupling process according to any one of claims 6 to 8 for the production of 2, 5-furandicarboxylic acid or for the integrated utilization of carbon dioxide.

10. An electrolysis apparatus, comprising: cathode, anode, container, diaphragm, wire, power supply and air vent;

the cathode is an electrode material prepared by the method of any one of claims 3 to 5, and the anode is a NiCo-loaded anode ₂ O ₄ The anode electrolyte is 5-hydroxymethyl furfural solution, and the cathode electrolyte is carbonate solution saturated by carbon dioxide;

wherein the membrane separates the container into a cathode chamber and an anode chamber; the cathode, the power supply and the anode are connected in sequence by leads;

the vent is disposed in the cathode chamber.