Furfural electrooxidation catalyst as well as preparation method and application thereof

Abstract

The invention relates to a furfural electro-oxidation catalyst as well as a preparation method and application thereof. The furfural electro-oxidation catalyst is applied to hydrogen production through furfural electro-oxidation coupling water electrolysis hydrogen evolution reaction under an alkaline condition. The furfural electrooxidation catalyst comprises copper nanowires derived from foamy copper doped with oxyphilic metal. The inactivation of the copper-based catalyst is delayed by introducing the oxyphilic metal, the oxyphilic metal enables copper to expose more active sites, and local electron transfer exists between the oxyphilic metal and the copper metal, so that the phenomenon that the metal copper is oxidized due to electron loss can be relieved. Meanwhile, the furfural electrooxidation catalyst is large in specific surface area, multiple in active sites and high in conductivity, the catalytic activity of the catalyst can be improved, and then the yield of a target product is improved. The catalyst is applied to furfural electrooxidation under the alkaline condition, a coupling hydrogen evolution reaction is carried out on an anode, the potential of hydrolysis hydrogen production can be reduced, and the hydrogen production efficiency can be further improved.

Description

Technical Field

[0001] The invention relates to the technical field of catalysts, in particular to a small molecule electro-oxidation coupled water electrolysis hydrogen production catalyst, and in particular to a furfural electro-oxidation catalyst and a preparation method and application thereof. Background Art

[0002] As human society continues to develop, energy demand is growing rapidly, a large amount of fossil energy is consumed, and the natural environment is seriously threatened. Therefore, it is urgent to develop more environmentally friendly and sustainable energy technologies. 2 ) has the characteristics of high energy density and no carbon emissions when used. It can be used as a clean energy carrier to replace fossil fuels, solve the energy crisis and alleviate environmental problems.

[0003] Currently, H 2 It is mainly produced by reforming traditional fossil resources (such as natural gas, oil and coal) under harsh conditions, which has the problems of carbon dioxide release and unsustainability. Water electrolysis combined with intermittent renewable energy has become a new energy source for the production of high-purity H 2 This provides a sustainable and effective strategy. However, the high energy consumption of water electrolysis limits its widespread application.

[0004] In the traditional water electrolysis system, the hydrogen evolution reaction (HER) occurs at the cathode and the oxygen evolution reaction (OER) occurs at the anode. Compared with HER, OER is a relatively complex four-electron transfer process with slow reaction kinetics and high theoretical decomposition potential (1.23V vs. RHE), which leads to a large overpotential for driving OER and seriously reduces the energy conversion efficiency of water electrolysis. At the same time, the product of OER, oxygen (O 2 ) may cross-link with H 2 An explosive mixture is formed and reactive oxygen species may be produced, which can degrade the ion exchange membrane in the electrolyzer and cause the performance of the water electrolysis device to rapidly deteriorate.

[0005] An effective strategy to solve the above-mentioned hydrogen production from water electrolysis is to use the thermodynamically more favorable electro-oxidation reaction of small molecules (such as alcohols and amines, etc.) instead of OER coupled with HER. The theoretical potential of these small molecule electro-oxidation is usually lower than that of OER, which can not only reduce the electrolyzer voltage, but also produce value-added products (such as carboxylic acids and nitriles) at the anode. However, the electrolyzer composed of the electro-oxidation of these organic small molecules coupled with HER still has a high electrolyzer voltage (>1.0V vs.RHE).

[0006] Researchers have found that low-potential electro-oxidation of furfural (FF) or 5-hydroxymethylfurfural (HMF) coupled with HER can achieve bipolar hydrogen production at a lower voltage (0.3V vs. RHE) in the electrolyzer, while producing high value-added products (furfuric acid or 2,5-furandicarboxylic acid, etc.) at the anode. Compared with the electro-oxidation process of other organic small molecules, the use of furfural small molecules can not only significantly reduce the electrolyzer voltage, but also achieve hydrogen production with lower energy consumption. The anode reaction equation is: When Cu-based materials are used as catalysts, the aldehyde reactants can be converted into the corresponding carboxylates and H at a low starting potential of only 0.05 V vs. RHE. 2 Due to the low oxidation potential, studies have shown that the H atom of the aldehyde group can undergo a Tafel step. Recombination releases H 2 , rather than the conventional aldehyde electrooxidation through the Volmer step Oxidation to H 2 O. It is worth mentioning that the reaction substrates FF and HMF used in the low-potential oxidation are very abundant and easily accessible biomass-derived platform molecules that can be obtained from a variety of sustainable biomass raw materials (such as starch, cellulose and hemicellulose), and their oxidation products (corresponding carboxylic acids) are important precursors of value-added chemicals and a series of products, which can be used to prepare drug molecules, perfumes or other polymers.

[0007] Furthermore, further studies have shown that only Ag and Cu can serve as electrodes for low-potential oxidation and achieve hydrogen production. In addition, Cu can better balance the toxic intermediate CO compared to Ag. * adsorption and activation of CH bonds, and provide suitable * H and * The binding strength of OH is increased, thereby achieving a low potential oxidation process.

[0008] However, to achieve rapid conversion of furfural molecules, the intrinsic activity of Cu-based catalysts must be improved. Otherwise, furfural will be partially lost through spontaneous polymerization or Cannizzaro side reaction. In addition, due to the poor stability of Cu-based catalysts, this poses a challenge to long-term stable electrolysis, thus limiting its further application. Therefore, it is crucial to develop stable, efficient and durable Cu-based catalysts. Summary of the invention

[0009] In order to solve the above technical problems, the present invention provides a furfural electro-oxidation catalyst and its preparation method and application. When the anode furfural electro-oxidation reaction is coupled with the cathode hydrogen evolution reaction to electrolyze water to produce hydrogen, the potential of electrolyzing water to produce hydrogen will be significantly reduced, and the hydrogen production efficiency will be further improved, but the required catalyst needs to have higher intrinsic activity and stability. The furfural electro-oxidation catalyst provided by the present invention delays the oxidation and deactivation of metallic copper due to loss of electrons by doping copper nanowires with oxophilic metals, and the copper nanowires have a large specific surface area and many active sites, high conductivity, and improved catalytic activity of the catalyst.

[0010] To achieve this object, the present invention adopts the following technical solutions:

[0011] In a first aspect, the present invention provides a furfural electro-oxidation catalyst, comprising copper nanowires derived from copper foam doped with an oxophilic metal; the oxophilic metal comprises a first oxophilic metal; and the first oxophilic metal comprises manganese.

[0012] The present invention delays the deactivation of the copper-based catalyst by introducing an oxophilic metal. The oxophilic metal competitively adsorbs hydroxide, thereby exposing more active sites to the copper, and there is local electron transfer between the oxophilic metal and the copper metal, which can further alleviate the phenomenon that the metal copper is oxidized due to the loss of electrons. At the same time, the prepared copper nanowire catalyst has a large specific surface area, which can expose more active sites and has high conductivity, which can further improve the catalytic activity of the catalyst, thereby improving the yield of the target product. The catalyst of the present invention is applied to the electro-oxidation of furfural under alkaline conditions, replacing the anode oxygen evolution reaction in the electrolysis of water to decouple the hydrogen evolution reaction, which can not only reduce the potential of hydrogen production by hydrolysis, but also further improve the efficiency of hydrogen production and the yield of hydrogen.

[0013] Preferably, the oxophilic metal further comprises a second oxophilic metal.

[0014] Preferably, the second oxophilic metal includes any one or a combination of at least two of tungsten, zirconium, cerium, titanium, chromium, palladium or rhodium. Typical but non-limiting combinations include a combination of tungsten and zirconium, a combination of cerium and titanium, or a combination of chromium, palladium and rhodium.

[0015] Preferably, the molar ratio of the first oxophilic metal to the second oxophilic metal is (0.5-1.5):1, for example, 0.5:1, 0.7:1, 0.9:1, 1:1, 1.3:1 or 1.5:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0016] Preferably, typical but non-limiting combinations of the oxophilic metals include a combination of manganese and tungsten, a combination of manganese and cerium, a combination of manganese and titanium, a combination of manganese and chromium, a combination of manganese and palladium, or a combination of manganese and rhodium.

[0017] Preferably, in the furfural electro-oxidation catalyst, the molar ratio of the first oxophilic metal to copper is 1:(40-60), for example, it can be 1:40, 1:45, 1:50, 1:55 or 1:60, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] In a second aspect, the present invention provides a method for preparing the furfural electro-oxidation catalyst as described in the first aspect, the preparation method comprising: cleaning a copper source to obtain a cleaned copper source, and then preparing copper hydroxide nanowires by an anodic oxidation method or a chemical immersion method; annealing the copper hydroxide nanowires to obtain cuprous oxide nanowires, and then hydrothermally treating the cuprous oxide nanowires to obtain the furfural electro-oxidation catalyst; the hydrothermally treated solution comprises a mixed solution of a first oxophilic metal source and urea.

[0019] Preferably, the hydrothermal treatment solution further comprises a second oxophilic metal source.

[0020] Preferably, in the hydrothermal treatment solution, the concentration of the first oxophilic metal source is 0.9 g / L-3.6 g / L, for example, 0.9 g / L, 1.8 g / L, 2.7 g / L, 3 g / L or 3.6 g / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] Preferably, in the hydrothermal treatment solution, the concentration of the second oxophilic metal source is 0.9 g / L-3.6 g / L, for example, 0.9 g / L, 1.8 g / L, 2.7 g / L, 3 g / L or 3.6 g / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0022] Preferably, in the hydrothermal treatment solution, the concentration of urea is 0.9 g / L-3.6 g / L, for example, 0.9 g / L, 1.8 g / L, 2.7 g / L, 3 g / L or 3.6 g / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] Preferably, the copper source comprises copper foam.

[0024] Preferably, the first oxophilic metal source solution comprises a first oxophilic metal sulfate solution and / or a first oxophilic metal chloride solution.

[0025] Preferably, the second oxophilic metal source solution comprises a second oxophilic metal sulfate solution and / or a second oxophilic metal chloride solution.

[0026] Preferably, the cleaning detergent includes any one of alcohol detergent, acid detergent or deionized water, or a combination of at least two of them. Typical but non-limiting combinations include a combination of alcohol detergent and acid detergent, or a combination of alcohol detergent, acid detergent and deionized water.

[0027] Preferably, the alcohol detergent comprises anhydrous ethanol.

[0028] Preferably, the washing time of the alcohol detergent is 5 min-15 min, for example, 5 min, 7 min, 9 min, 10 min, 13 min or 15 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] Preferably, the acid detergent comprises hydrochloric acid.

[0030] Preferably, the concentration of the hydrochloric acid is 0.5mol / L-1.5mol / L, for example, 0.5mol / L, 0.7mol / L, 1mol / L, 1.2mol / L or 1.5mol / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] Preferably, the washing time of the acid detergent is 5 min-15 min, for example, 5 min, 7 min, 9 min, 10 min, 13 min or 15 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0032] Preferably, the washing time of the deionized water is 5 min-15 min, for example, 5 min, 7 min, 9 min, 10 min, 13 min or 15 min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0033] Preferably, the cleaning method comprises ultrasonic cleaning.

[0034] Preferably, the steps of the anodization method include: using a platinum sheet as a counter electrode, anodizing the cleaned copper source in an alkaline electrolyte to prepare copper hydroxide nanowires.

[0035] Preferably, the alkaline electrolyte includes sodium hydroxide solution and / or potassium hydroxide solution.

[0036] Preferably, the concentration of the alkaline electrolyte is 0.5mol / L-1.5mol / L, for example, 0.5mol / L, 0.7mol / L, 1mol / L, 1.2mol / L or 1.5mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0037] Preferably, the anodization time is 5 min-30 min, for example, 5 min, 10 min, 15 min, 20 min, 25 min or 30 min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0038] The present invention can not only improve the density of the copper hydroxide nanowire array by further regulating the time of anodic oxidation, but also further improve the mass transfer effect of the catalyst, thereby improving the catalytic activity of the catalyst. Within the preferred range of anodic oxidation time, the prepared copper hydroxide nanowire array has a uniform and moderate density, the catalyst has many active sites, good mass transfer effect, and high catalytic efficiency.

[0039] Preferably, the current density of the anodization is 20 mA / cm 2 -100 mA / cm 2 , for example 20mA / cm 2 , 40mA / cm 2 、60mA / cm 2 、80mA / cm 2 or 100mA / cm 2 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

[0040] The present invention can further control the diameter of the copper hydroxide nanowire array by further controlling the current density of the anodic oxidation, which can not only improve the density of the copper hydroxide nanowire array, but also further improve the mass transfer effect of the catalyst, thereby improving the catalytic activity of the catalyst. Within the preferred anodic oxidation current density range, the prepared copper hydroxide nanowire array has a moderate diameter, the density of the nanowire array per unit area is uniform and moderate, the catalyst has many active sites, the mass transfer effect is good, and the catalytic efficiency of the catalyst is high.

[0041] Preferably, the chemical immersion method comprises: immersing the cleaned copper source in a mixed solution to prepare copper hydroxide nanowires.

[0042] Preferably, the mixed solution comprises an alkaline solution and an ammonium thiosulfate solution.

[0043] Preferably, the concentration of the alkaline solution is 2.5mol / L-3mol / L, for example, 2.5mol / L, 2.6mol / L, 2.7mol / L, 2.9mol / L or 3mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0044] Preferably, the alkaline solution comprises sodium hydroxide solution and / or potassium hydroxide solution.

[0045] Preferably, the concentration of the sodium thiosulfate solution is 0.1 mol / L-0.2 mol / L, for example, 0.1 mol / L, 0.13 mol / L, 0.15 mol / L, 0.18 mol / L or 0.2 mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0046] Preferably, the soaking time is 20 min-40 min, for example, 20 min, 25 min, 30 min, 35 min, 39 min or 40 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0047] The present invention can not only improve the density of the copper hydroxide nanowire array by further regulating the soaking time, but also further improve the mass transfer effect of the catalyst, thereby improving the catalytic activity of the catalyst. Within the preferred soaking time range, the prepared copper hydroxide nanowire array has a uniform and moderate density, the catalyst has many active sites, the mass transfer effect is good, and the catalytic efficiency of the catalyst is high.

[0048] Preferably, the holding temperature of the annealing treatment is 300°C-500°C, for example, 300°C, 350°C, 400°C, 450°C or 500°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0049] The present invention further regulates the conversion rate of the copper hydroxide array being thermally reduced to the cuprous oxide array by further regulating the annealing temperature. Within the preferred annealing temperature range, not only can the copper hydroxide array be completely thermally reduced to the cuprous oxide array, but also the original morphology of the nanowire array can be maintained, and the density of the nanowire array can be kept unchanged.

[0050] Preferably, the heating rate of the annealing treatment is 3°C / min-6°C / min, for example, 3°C / min, 4°C / min, 5°C / min, 5.5°C / min or 6°C / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0051] Preferably, the holding time of the annealing treatment is 1 h-3 h, for example, 1 h, 1.5 h, 2 h, 2.5 h or 3 h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0052] Preferably, the ambient atmosphere of the annealing treatment includes an inert gas atmosphere.

[0053] Preferably, the inert gas atmosphere includes a nitrogen atmosphere and / or an argon atmosphere.

[0054] Preferably, the holding temperature of the hydrothermal treatment is 100°C-150°C, for example, 100°C, 110°C, 120°C, 140°C or 150°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0055] Preferably, the holding time of the hydrothermal treatment is 4 h-12 h, for example, 4 h, 6 h, 8 h, 10 h or 12 h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0056] Preferably, the hydrothermal treatment is followed by washing and drying.

[0057] Preferably, the washing detergent comprises deionized water.

[0058] Preferably, the drying insulation temperature is 50°C-70°C, for example, 50°C, 55°C, 60°C, 65°C or 70°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0059] Preferably, the drying heat preservation time is 8h-16h, for example, 8h, 10h, 12h, 14h or 16h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0060] As a preferred technical solution of the present invention, the method for preparing the furfural electro-oxidation catalyst comprises the following steps:

[0061] (1) ultrasonically cleaning the copper foam, wherein the ultrasonic cleaning comprises sequentially cleaning with hydrochloric acid for 5 min to 15 min, cleaning with anhydrous ethanol for 5 min to 15 min, and cleaning with deionized water for 5 min to 15 min, to obtain the cleaned copper foam.

[0062] (2) Using a platinum sheet as the counter electrode, the cleaned copper foam was placed in an alkaline electrolyte of 0.5 mol / L-1.5 mol / L at 20 mA / cm 2 -100 mA / cm 2 The current density was used for anodic oxidation for 5 min-30 min to obtain Cu(OH) 2 of nanowires.

[0063] Alternatively, the cleaned copper foam is immersed in a mixed solution of 2.5mol / L-3mol / L alkaline solution and 0.1mol / L-0.2mol / L sodium thiosulfate solution for 20min-40min to obtain Cu(OH) 2 Nanowires.

[0064] (3) Cu(OH) 2 The nanowires were heated to 300-500°C at a heating rate of 3-6°C / min in an inert gas atmosphere and annealed for 1-3 hours to obtain Cu 2 O nanowires.

[0065] (4) Cu 2 The O nanowires are immersed in a mixed solution of 1.8 g / L-7.2 g / L oxophilic metal source solution and 0.9 g / L-3.6 g / L urea solution, and then hydrothermally treated at 100°C-150°C for 4h-12h, first washed with deionized water, and then dried at 50°C-70°C for 8h-16h to obtain an oxophilic metal-doped copper nanowire furfural electro-oxidation catalyst; the oxophilic metal source solution includes 0.9 g / L-3.6 g / L of a first oxophilic metal source, and the oxophilic metal source solution also includes 0.9 g / L-3.6 g / L of a second oxophilic metal source.

[0066] In a third aspect, the present invention provides an application of a furfural electro-oxidation catalyst as described in the first aspect, wherein the furfural electro-oxidation catalyst is applied to produce hydrogen by coupling the electrolysis of water with the electrooxidation of furfural under alkaline conditions; the electrolyte for producing hydrogen by electrolysis of water comprises furfural at a concentration of 10 mmol / L-100 mmol / L.

[0067] Specifically, the concentration of furfural in the electrolyte can be 10mmol / L, 30mmol / L, 50mmol / L, 70mmol / L, 90mmol / L or 100mmol / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0068] Preferably, the process of producing hydrogen by electrolysis of water comprises: placing a copper electrode in an anode electrolysis chamber containing a potassium hydroxide electrolyte containing furfural, placing a platinum electrode in a cathode electrolysis chamber containing a potassium hydroxide electrolyte, connecting an electrochemical workstation for electrolysis, and collecting the gases generated by the cathode and anode respectively through a gas collection device.

[0069] Compared with the prior art, the present invention has at least the following beneficial effects:

[0070] (1) The present invention delays the deactivation of the copper-based catalyst by introducing an oxophilic metal. The oxophilic metal competitively adsorbs hydroxide, thereby exposing more active sites of copper. There is also local electron transfer between the oxophilic metal and copper metal, which can further alleviate the phenomenon of metallic copper being oxidized due to loss of electrons.

[0071] (2) The furfural electro-oxidation catalyst of the present invention has a large specific surface area, a large number of active sites, and a high conductivity, which can improve the catalytic activity of the catalyst and thus increase the yield of the target product.

[0072] (3) When the catalyst of the present invention is used for furfural electrooxidation under alkaline conditions to replace the anodic oxygen evolution reaction in electrolyzed water to decouple the hydrogen evolution reaction, adding furfural to the anolyte can not only reduce the oxidation potential of hydrogen production by hydrolysis, but also further improve the efficiency of hydrogen production and the yield of hydrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] Figure 1 is a scanning electron microscope image of the furfural electro-oxidation catalyst described in Example 1 of the present invention;

[0074] Figure 2 is the XRD diagram of the furfural electro-oxidation catalyst described in Example 1 of the present invention;

[0075] Figure 3 1 is the linear sweep voltammetry curve of the furfural electro-oxidation catalyst described in Example 1 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0076] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0077] Example 1

[0078] The present embodiment provides a furfural electro-oxidation catalyst, the furfural electro-oxidation catalyst comprising copper nanowires derived from manganese-doped copper foam, the molar ratio of manganese element to copper element being 1:50, and the preparation method of the furfural electro-oxidation catalyst comprising the following steps:

[0079] (1) ultrasonically cleaning the copper foam, wherein the ultrasonic cleaning comprises sequentially cleaning with 1 mol / L hydrochloric acid for 10 min, cleaning with anhydrous ethanol for 10 min, and cleaning with deionized water for 10 min to obtain the cleaned copper foam;

[0080] (2) Using a platinum sheet as the counter electrode, the cleaned copper foam was placed in a 1 mol / L sodium hydroxide electrolyte at 60 mA / cm 2 The current density was 20 min for anodization to obtain Cu(OH) 2 of nanowires;

[0081] (3) Cu(OH) 2 The nanowires were heated to 400°C at a heating rate of 5°C / min in an argon atmosphere and annealed for 2 h to obtain Cu 2 O nanowires;

[0082] (4) Cu 2O nanowires were immersed in 1.8 g / L MnSO 4 ·H 2 O solution and 1.8 g / L urea solution, and then hydrothermally treated at 120 °C for 10 h, washed with deionized water, and then dried at 60 °C for 12 h to obtain the furfural electro-oxidation catalyst of manganese-doped copper nanowires.

[0083] Figure 1 is a scanning electron microscope image of the furfural electro-oxidation catalyst described in Example 1 of the present invention, Figure 2 3 is the XRD diagram of the furfural electro-oxidation catalyst described in Example 1 of the present invention. It can be seen from the figure that the furfural electro-oxidation catalyst prepared in this example has a clear nanowire structure and its main component is metallic copper.

[0084] Example 2

[0085] The present embodiment provides a furfural electro-oxidation catalyst, the furfural electro-oxidation catalyst comprising copper nanowires derived from titanium-manganese doped copper foam, the molar ratio of the titanium element to the manganese element being 1:1, and the molar ratio of the manganese element to the copper element being 1:40, and the preparation method of the furfural electro-oxidation catalyst comprising the following steps:

[0086] (1) ultrasonically cleaning the copper foam, wherein the ultrasonic cleaning comprises sequentially cleaning with 1.5 mol / L hydrochloric acid for 5 min, cleaning with anhydrous ethanol for 5 min, and cleaning with deionized water for 5 min to obtain the cleaned copper foam;

[0087] (2) Using a platinum sheet as the counter electrode, the cleaned copper foam was placed in a 0.5 mol / L potassium hydroxide electrolyte at 20 mA / cm 2 The current density was 0.0447 W / m and the anodization was carried out for 30 min to obtain Cu(OH) 2 of nanowires;

[0088] (3) Cu(OH) 2 The nanowires were heated to 300°C at a heating rate of 3°C / min in a nitrogen atmosphere and annealed for 3 h to obtain Cu 2 O nanowires;

[0089] (4) Cu 2 O nanowires were immersed in 0.9 g / L titanium chloride solution, 0.9 g / L MnSO 4 ·H 2 O solution and 0.9 g / L urea solution, and then hydrothermally treated at 150 °C for 4 h, washed with deionized water, and then dried at 50 °C for 16 h to obtain the titanium manganese doped copper nanowires furfural electro-oxidation catalyst.

[0090] Example 3

[0091] The present embodiment provides a furfural electro-oxidation catalyst, the furfural electro-oxidation catalyst comprising copper nanowires derived from cerium-manganese doped copper foam, the molar ratio of the cerium element to the manganese element is 1:1.5, the molar ratio of the manganese element to the copper element is 1:60, and the preparation method of the furfural electro-oxidation catalyst comprises the following steps:

[0092] (1) ultrasonically cleaning the copper foam, wherein the ultrasonic cleaning comprises sequentially cleaning with 0.5 mol / L hydrochloric acid for 15 min, cleaning with anhydrous ethanol for 15 min, and cleaning with deionized water for 15 min to obtain the cleaned copper foam;

[0093] (2) The cleaned copper foam was immersed in a mixed solution of 2.67 mol / L sodium hydroxide solution and 0.13 mol / L sodium thiosulfate solution for 30 min to obtain Cu(OH) 2 Nanowires;

[0094] (3) Cu(OH) 2 The nanowires were heated to 500°C at a heating rate of 6°C / min in a nitrogen atmosphere and annealed for 1 h to obtain Cu 2 O nanowires;

[0095] (4) Cu 2 O nanowires were immersed in 3.6 g / L cerium sulfate source solution, 3.6 g / L MnSO 4 ·H 2 O solution and 3.6 g / L urea solution, and then hydrothermally treated at 100 °C for 12 h, washed with deionized water, and then dried at 70 °C for 8 h to obtain the furfural electro-oxidation catalyst of cerium-doped copper nanowires.

[0096] Example 4

[0097] The only difference between this embodiment and embodiment 1 is that, except for the time of anodization in step (2) being 3 minutes, the rest is the same as embodiment 1.

[0098] Example 5

[0099] The only difference between this embodiment and embodiment 1 is that, except for the time of anodization in step (2) being 32 minutes, the rest is the same as embodiment 1.

[0100] Example 6

[0101] The only difference between this embodiment and embodiment 1 is that, except that the holding temperature of the annealing treatment in step (3) is 250° C., the rest is the same as embodiment 1.

[0102] Example 7

[0103] The only difference between this embodiment and embodiment 1 is that, except that the holding temperature of the annealing treatment in step (3) is 550° C., the rest is the same as embodiment 1.

[0104] Example 8

[0105] The only difference between this embodiment and embodiment 1 is that, except that the holding temperature of the hydrothermal treatment in step (4) is 90° C., the rest is the same as embodiment 1.

[0106] Example 9

[0107] The only difference between this embodiment and embodiment 1 is that, except that the holding temperature of the hydrothermal treatment in step (4) is 160° C., the rest is the same as embodiment 1.

[0108] Comparative Example 1

[0109] The only difference between this comparative example and Example 1 is that, except that the mixed solution in step (4) only includes 0.9 g / L urea solution, the rest is the same as Example 1.

[0110] Figure 3 It is the linear sweep voltammetry curve of the catalyst described in Example 1 of the present invention and Comparative Example 1. It can be seen from the figure that compared with the undoped copper catalyst, the manganese-doped copper catalyst has a higher furfural oxidation current at the same voltage, indicating that manganese doping improves the catalytic activity of the copper catalyst.

[0111] Comparative Example 2

[0112] The difference between this comparative example and Example 1 is that, except for not performing step (4), the rest is the same as Example 1.

[0113] Comparative Example 3

[0114] The difference between this comparative example and Example 1 is that, except that step (2) to step (4) are not performed, the rest are the same as Example 1.

[0115] Comparative Example 4

[0116] This comparative example provides a furfural electro-oxidation catalyst, the furfural electro-oxidation catalyst comprising copper nanowires derived from cobalt-doped copper foam, the molar ratio of the cobalt element to the copper element being 1:50, and the preparation method of the furfural electro-oxidation catalyst comprising the following steps:

[0117] (1) ultrasonically cleaning the copper foam, wherein the ultrasonic cleaning comprises sequentially cleaning with 1 mol / L hydrochloric acid for 10 min, cleaning with anhydrous ethanol for 10 min, and cleaning with deionized water for 10 min to obtain the cleaned copper foam;

[0118] (2) Using a platinum sheet as the counter electrode, the cleaned copper foam was placed in a 1 mol / L sodium hydroxide electrolyte at 60 mA / cm 2 The current density was 20 min for anodization to obtain Cu(OH) 2 of nanowires;

[0119] (3) Cu(OH) 2 The nanowires were heated to 400°C at a heating rate of 5°C / min in an inert gas atmosphere and annealed in an argon atmosphere for 2 h to obtain Cu 2 O nanowires;

[0120] (4) Cu 2 O nanowires were immersed in 1.8 g / L CoSO 4 The mixture was added into a mixed solution of the solution and 1.8 g / L urea solution and then hydrothermally treated at 120°C for 10 h, washed with deionized water and then dried at 60°C for 12 h to obtain a furfural electro-oxidation catalyst of manganese-doped copper nanowires.

[0121] Test Method

[0122] The furfural electro-oxidation catalysts described in Examples 1 to 9 and Comparative Examples 1 to 4 were used as working electrodes, furfural was added to an electrolytic cell, and platinum was used as a counter electrode to electrolyze water to produce hydrogen. The prepared hydrogen and furoic acid were collected, and their yields were calculated and recorded in Table 1.

[0123] Table 1

[0124]

[0125]

[0126] The test results show that:

[0127] (1) It can be seen from Examples 1 to 9 and Comparative Examples 1 to 4 that the present invention delays the deactivation of the copper-based catalyst by introducing an oxophilic metal. The oxophilic metal will competitively adsorb hydroxide, thereby exposing more active sites to the copper, and there will be local electron transfer between the oxophilic metal and the copper metal, which can further alleviate the phenomenon of oxidation of metallic copper due to loss of electrons. At the same time, the prepared copper nanowire catalyst has a large specific surface area, which can expose more active sites and has high conductivity, which can further improve the catalytic activity of the catalyst and thus improve the yield of the target product. The catalyst of the present invention is applied to the electro-oxidation of furfural under alkaline conditions. When the anodic oxygen evolution reaction is replaced by the decoupling hydrogen evolution reaction in the electrolyzed water, furfural is added to the anodic electrolyte, which can not only reduce the oxidation potential of hydrogen production by hydrolysis, but also further improve the efficiency of hydrogen production and the yield of hydrogen.

[0128] (2) It can be seen from Example 1 and Example 4-Example 5 that the present invention can further increase the yield of hydrogen and furoic acid by further regulating the time of anodic oxidation.

[0129] (3) It can be seen from Example 1 and Example 6-Example 7 that the present invention can further increase the yield of hydrogen and furoic acid by further regulating the holding temperature of the annealing treatment.

[0130] (4) It can be seen from Example 1 and Example 8-Example 9 that the present invention can further increase the yield of hydrogen and furoic acid by further regulating the holding temperature of the hydrothermal treatment.

[0131] In summary, the present invention delays the deactivation of copper-based catalysts by introducing oxophilic metals. Oxophilic metals competitively adsorb hydroxides, thereby exposing more active sites to copper, and there will be local electron transfer between oxophilic metals and copper metal, which can further alleviate the phenomenon of oxidation of metallic copper due to loss of electrons. At the same time, the prepared copper nanowire catalyst has a large specific surface area, which can expose more active sites and has high conductivity, which can further improve the catalytic activity of the catalyst, thereby improving the yield of the target product. The catalyst of the present invention is applied to the electro-oxidation of furfural under alkaline conditions. When replacing the anodic oxygen evolution reaction in electrolyzed water to decouple the hydrogen evolution reaction, furfural is added to the anodic electrolyte, which can not only reduce the oxidation potential of hydrogen production by hydrolysis, but also further improve the efficiency of hydrogen production and the yield of hydrogen.

[0132] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A furfural electro-oxidation catalyst, characterized in that: The furfural electro-oxidation catalyst comprises copper nanowires derived from copper foam doped with an oxophilic metal; The oxophilic metal comprises a first oxophilic metal; The first oxophilic metal includes manganese.

2. The furfural electro-oxidation catalyst according to claim 1, characterized in that: The oxophilic metal further comprises a second oxophilic metal; Preferably, the second oxophilic metal comprises any one or a combination of at least two of tungsten, zirconium, cerium, titanium, chromium, palladium or rhodium; Preferably, the molar ratio of the first oxophilic metal to the second oxophilic metal is (0.5-1.5):

1.

3. The furfural electro-oxidation catalyst according to claim 1 or 2, characterized in that: In the furfural electro-oxidation catalyst, the molar ratio of the first oxophilic metal to copper is 1:(40-60).

4. A method for preparing the furfural electro-oxidation catalyst according to any one of claims 1 to 3, characterized in that: The preparation method comprises: The copper source is cleaned to obtain a cleaned copper source, and then an anodic oxidation method or a chemical immersion method is used to prepare copper hydroxide nanowires; the copper hydroxide nanowires are annealed to obtain cuprous oxide nanowires, and then the cuprous oxide nanowires are hydrothermally treated to obtain the furfural electro-oxidation catalyst; The hydrothermal treatment solution includes a mixed solution of a first oxophilic metal source and urea.

5. The preparation method according to claim 4, characterized in that: The copper source includes foamed copper; Preferably, the first oxophilic metal source solution comprises a first oxophilic metal sulfate solution and / or a first oxophilic metal chloride solution; Preferably, the cleaning detergent comprises any one of an alcohol detergent, an acid detergent or deionized water, or a combination of at least two thereof; Preferably, the cleaning method comprises ultrasonic cleaning.

6. The preparation method according to claim 4 or 5, characterized in that: The steps of the anodizing method include: using a platinum sheet as a counter electrode, anodizing the cleaned copper source in an alkaline electrolyte to prepare copper hydroxide nanowires.

7. The preparation method according to claim 6, characterized in that: The alkaline electrolyte includes sodium hydroxide solution and / or potassium hydroxide solution; Preferably, the anodizing time is 5 min-30 min; Preferably, the current density of the anodization is 20 mA / cm 2 -100 mA / cm 2 .

8. The preparation method according to claim 4, characterized in that: The chemical soaking method comprises: soaking the cleaned copper source in a mixed solution to prepare copper hydroxide nanowires; Preferably, the mixed solution comprises an alkaline solution and an ammonium thiosulfate solution; Preferably, the soaking time is 20 min-40 min.

9. The preparation method according to any one of claims 4 to 8, characterized in that: The holding temperature of the annealing treatment is 300°C-500°C; Preferably, the holding time of the annealing treatment is 1h-3h; Preferably, the holding temperature of the hydrothermal treatment is 100°C-150°C; Preferably, the holding time of the hydrothermal treatment is 4h-12h.

10. Use of the furfural electro-oxidation catalyst according to any one of claims 1 to 3, characterized in that: The furfural electro-oxidation catalyst is applied to produce hydrogen by coupling the electro-oxidation of furfural with the hydrogen evolution reaction of water electrolysis under alkaline conditions; the electrolyte for producing hydrogen by water electrolysis comprises furfural with a concentration of 10 mmol / L-100 mmol / L.

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