阅读说明：本技术 一种新型电催化还原二氧化碳电极材料及其制备方法及应用 (Novel electrocatalytic reduction carbon dioxide electrode material and preparation method and application thereof ) 是由 安长华 马小茗 姚爽 闫文秀 安超 肖雄 于 2019-08-20 设计创作，主要内容包括：本发明提供了一种新型电催化还原二氧化碳电极材料及其制备方法和应用,所述电极材料具有三维纳米多孔结构,表面富金而形成核壳结构,表达式为AuCu_3@Au。通过Fe~(3+)一步氧化刻蚀Au_(20)Cu_(80)中的Cu,得到表面富金的纳米多孔AuCu_3@Au核壳结构。将Au_(20)Cu_(80)的金属条带置于Fe~(3+)溶液中得到孔径、韧带分布均匀,表面富金的核壳结构AuCu_3@Au。这种电极表现出优异的电催化还原二氧化碳性能,在RHE为-0.6V时CO的法拉第效率为97.27％,一氧化碳的分电流密度为5.3mA/cm。由于其良好的导电性和柔韧性,可直接制备长度约为23厘米的AuCu_3多孔电极,在RHE为-0.7V时电流达到37.2mA。该发明为电催化还原二氧化碳提供了新的催化剂研发思路,为其工业化应用提供了简易技术。(The invention provides a novel electrocatalytic reduction carbon dioxide electrode material and a preparation method and application thereof, wherein the electrode material has a three-dimensional nano porous structure, the surface of the electrode material is rich in gold to form a core-shell structure, and the expression is AuCu 3 @ Au. By Fe 3+ One-step oxidation etching Au 20 Cu 80 The Cu in the solution is used for obtaining the nano porous AuCu with gold-rich surface 3 @ Au core-shell structure. Mixing Au 20 Cu 80 Is placed in Fe 3+ Obtaining the core-shell structure AuCu with uniform pore diameter and ligament distribution and gold-rich surface in the solution 3 @ Au. The electrode shows excellent performance of electrocatalytic reduction of carbon dioxide, and farad of CO at RHE of-0.6VThe first efficiency was 97.27%, and the partial current density of carbon monoxide was 5.3 mA/cm. Because of good conductivity and flexibility, AuCu with the length of about 23cm can be directly prepared 3 The current of the porous electrode reaches 37.2mA at the RHE of-0.7V. The invention provides a new catalyst research and development idea for electrocatalytic reduction of carbon dioxide and provides a simple technology for industrial application of the catalyst.)

1. A novel electrocatalytic reduction carbon dioxide electrode material is characterized in that: the electrode material has a three-dimensional nano porous structure, the surface of the electrode material is rich in gold to form a core-shell structure, the ratio of gold to copper of the surface shell is 2:1, the ratio of gold to copper of the interior of the electrode material is 1:3, and the expression is AuCu₃@Au。

2. A method for preparing the novel electrocatalytic reduction carbon dioxide electrode material as set forth in claim 1, which comprises the steps of:

(1) adding 0.0325-1g FeCl into 40-100mL deionized water₃Magnetically stirring to obtain solution A;

(2) weighing 40-80mg of Au raw material₂₀Cu₈₀Adding the solution A, and magnetically stirring for 30 min;

(3) washing with deionized water for several times, and drying in a vacuum drying oven for 6-12 h.

3. Use of the electrocatalytic reduction carbon dioxide electrode material of claim 1 for electrocatalytic reduction of carbon dioxide.

4. Use of the electrocatalytic reduction carbon dioxide electrode material of claim 1 for the preparation of bulk large electrodes.

Technical Field

The invention belongs to the technical field of electrocatalytic materials, and particularly relates to a three-dimensional nano porous core-shell AuCu with gold-rich surface₃An electrocatalytic reduction carbon dioxide electrode material, a preparation method and application thereof.

Background

Electrocatalytic conversion of carbon dioxide into fuels that can be utilized by humans is of great importance. The carbon monoxide is used as a material with wide application, and plays an important role in the aspects of generating high-carbon liquid fuel from Fischer-Tropsch reaction raw material gas, synthesizing a series of organic chemical products and intermediates and the like. Meanwhile, carbon dioxide is accumulated in human production and life continuously, so that the greenhouse effect caused by the increasing content has serious negative influence on the environment. Therefore, the conversion of excessive carbon dioxide in the air into chemical fuels useful for people's life is not slow, and the conversion of carbon dioxide into industrial raw materials by the electrocatalysis technology draws wide attention at home and abroad.

The key to the electrocatalytic conversion of carbon dioxide to industrial feedstocks is the discovery of suitable electrode materials. Gold can efficiently convert carbon dioxide into carbon monoxide in the process of electrocatalytic reduction of carbon dioxide, but the application of gold is limited because the gold is expensive and is greatly influenced by voltage in the reaction process. Copper is currently the only known electrode material capable of converting carbon dioxide to C2 and C3 and is inexpensive. Currently, single copper has low activity and low selectivity in the electrocatalytic reduction process of carbon dioxide.

Therefore, how to solve the above defects is the problem to be solved by the present invention.

Disclosure of Invention

The invention provides a novel electro-catalytic reduction methodThe carbon dioxide electrode material, the preparation method and the application thereof not only greatly improve the activity, the selectivity and the stability of the electrocatalytic reduction of the carbon dioxide, but also realize the large-scale nano porous AuCu with good ductility₃The preparation of the @ Au electrode has great significance for promoting the industrialization of the electrocatalytic reduction of the carbon dioxide.

In order to solve the technical problems, the invention adopts the following technical scheme:

a novel electrocatalytic reduction carbon dioxide electrode material has a three-dimensional nano porous structure, gold is enriched on the surface of the electrode material to form a core-shell structure, the electrocatalytic reduction carbon dioxide performance can be greatly improved, and the expression of the electrode material is as follows: AuCu₃@Au。

The preparation method of the novel electrocatalytic reduction carbon dioxide electrode material comprises the following steps:

(1) adding 0.0325-1g FeCl into 40-100mL deionized water₃Magnetically stirring to obtain solution A;

(2) weighing 40-80mg of Au raw material₂₀Cu₈₀Adding the solution A, and magnetically stirring for 30 min;

(3) washing with deionized water for several times, and drying in a vacuum drying oven for 6-12 h.

The application of the electrocatalytic reduction carbon dioxide electrode material in the aspect of electrocatalytic reduction of carbon dioxide.

The application of the electrocatalytic reduction carbon dioxide electrode material in preparing a bulk large electrode is provided. The nanoporous AuCu of the invention₃@ Au can be used for preparing bulk large electrodes, i.e. the electrodes can be made longer.

The invention selects and synthesizes the AuCu bimetallic electrode material, thereby not only reducing the cost, but also improving the selectivity of the copper to CO, and simultaneously, the porous AuCu bimetallic electrode material₃The electrode can realize a long-term reaction of 100 hours. In addition, the porous structure causes the surface of the catalyst to have a plurality of concave-convex surfaces and high-density atomic steps and kinks, and the nodes are generally considered as active centers of catalytic reaction. In addition, the core-shell structure generated by the gold-rich surface not only reduces the surface coordination number, but also reduces the Cu to oxide such as: CO 2_ads and OH_adsThereby inhibiting HER reaction and improving desorption of CO. More importantly, large nanoporous AuCu with good ductility was achieved₃Preparation of electrode promotes CO₂The practical application of electrocatalysis reduction technology.

By Fe³⁺One-step oxidation etching Au₂₀Cu₈₀The Cu in the solution is used for obtaining the nano porous AuCu with gold-rich surface₃@ Au core-shell structure. Mixing Au₂₀Cu₈₀Is placed in Fe³⁺Obtaining the core-shell structure AuCu with uniform pore diameter and ligament distribution and gold-rich surface in the solution₃@ Au. The electrode shows excellent performance of electrocatalytic reduction of carbon dioxide, the Faraday efficiency of CO is 97.27% at RHE of-0.6V, and the partial current density of carbon monoxide is 5.3 mA/cm. Because of good conductivity and flexibility, AuCu with the length of about 23cm can be directly prepared₃The current of the porous electrode reaches 37.2mA at the RHE of-0.7V. The invention provides a new catalyst research and development idea for electrocatalytic reduction of carbon dioxide and provides a simple technology for industrial application of the catalyst.

The invention provides a preparation method and application of a novel electrocatalytic reduction carbon dioxide electrode, and the electrode material is three-dimensional nano porous AuCu₃The surface of the core-shell structure is rich in gold layers. The method has the characteristics of simple process, low cost and good repeatability, and can be used for preparing the electrocatalytic reduction carbon dioxide electrode with controllable components, high activity and selectivity and good stability.

The three-dimensional nanoporous core-shell structure AuCu with gold-rich surface₃The @ Au electrode material is prepared by the following steps:

(1) 0.0325g FeCl was added to 40mL deionized water₃Magnetically stirring to obtain solution A;

(2) weighing 40mg of raw material Au₂₀Cu₈₀Adding the solution A, and magnetically stirring for 30 min;

(3) washing with deionized water for several times, and drying in a vacuum drying oven for 6-12 h.

The application of the electrocatalytic reduction carbon dioxide electrode material in the aspect of electrocatalytic reduction of carbon dioxide.

The invention develops a three-dimensional nano porous AuCu with a core-shell structure₃@ Au electrode material, the Faraday efficiency of CO was 97.27% at RHE of-0.6V, at which time the partial current density of CO was 5.3mA/cm²And the compound has good activity, selectivity and stability.

Novel nanoporous AuCu₃The study on the performance of the @ Au electrode in the electrocatalytic reduction of carbon dioxide comprises the following steps:

respectively preparing 40mL of 0.5M KHCO₃Placing the solution in two half cells of an H-type electrolytic cell, and selecting 2 cm-long AuCu₃The electrode material is used as a working electrode, a platinum sheet is selected as a counter electrode, a silver-silver chloride electrode is selected as a reference electrode, high-purity carbon dioxide is introduced into the solution for 30min, the solution is tested by a CHI 760E electrochemical workstation under magnetic stirring, sampling is carried out at intervals of 25min, and the product enters a gas chromatograph to be analyzed to determine the content of the product. And recovering the catalyst after the reaction is finished.

The catalyst is prepared by adopting an oxidation etching method: in Fe³⁺The AuCu with uniform pore diameter distribution and gold-rich core-shell structure on the surface is obtained in the system₃@ Au electrode. The electrocatalytic material prepared by the invention has high activity, selectivity and stability, and can be directly used as an electrode; the current of the prepared long bulk electrode reaches 37.2mA when the RHE is-0.7V, and the industrial application of electrocatalytic reduction of carbon dioxide is promoted. These characteristics indicate that the electrode material is in CO₂The resource recycling application field has higher application value.

The most preferable composition of the nano porous electrode material with the core-shell structure is as follows: the ratio of gold to copper on the surface shell is 2:1, the ratio of gold to copper in the interior is 1:3, and the expression is AuCu₃@ Au. The existence of the surface copper enables electron transfer between gold and copper, and the average coordination number of the Au surface is reduced, so that the free energy of the COOH is reduced, and the separation efficiency of CO is improved. In addition, the formation of a porous structure enables a large number of active sites to be formed on the surface, which is beneficial to CO₂Adsorption of (3).

The electrode material has good application effect in the aspect of electrocatalytic reduction of carbon dioxide, and is a novel electrocatalytic material which accords with the cyclic utilization of carbon resources.

Compared with the prior art, the invention has the advantages and positive effects that: the invention prepares the novel three-dimensional nano-porous electrocatalytic reduction carbon dioxide electrode with the core-shell structure by a simple one-step method, and is effectively applied to electrocatalytic reduction of carbon dioxide.

Drawings

FIG. 1 shows AuCu prepared in example 1 of the present invention₃SEM photograph of @ Au product;

FIG. 2 shows AuCu prepared in example 1 of the present invention₃The XRD diffraction pattern of the @ Au product;

FIG. 3 shows AuCu prepared in example 1 of the present invention₃TEM photographs of @ Au products;

FIG. 4 shows AuCu prepared in example 1 of the present invention₃HAADF-STEM photograph of @ Au product;

FIG. 5 shows AuCu prepared in example 1 of the present invention₃XPS and content plots for @ Au products;

FIG. 6 shows AuCu prepared in example 2 of the present invention₃Graph of electrocatalytic reduction carbon dioxide performance of @ Au product;

FIG. 7 shows AuCu prepared in example 2 of the present invention₃Graph of electrocatalytic reduction carbon dioxide stability for @ Au product;

FIG. 8 shows AuCu prepared in example 2 of the present invention₃SEM photograph of @ Au after 100 hours stability test;

FIG. 9 shows 23cm AuCu prepared in examples 3-4 of the present invention₃@ Au electrocatalytic reduction carbon dioxide performance diagram;

Detailed Description

Aiming at the defects of the prior art, the invention provides AuCu with a nano-porous core-shell structure₃The preparation method of @ Au and the application of converting carbon dioxide into carbon monoxide.

(1) 0.0325g FeCl was added to 40mL deionized water₃Magnetically stirring to obtain solution A;

(2) weighing 40mg of raw material Au₂₀Cu₈₀Adding the solution A, and magnetically stirring for 30 min;

(3) washing with deionized water for several times, and vacuum drying for 6-12 hr.

The invention develops a three-dimensional nano porous AuCu with a core-shell structure₃According to the electrode preparation technology, when the RHE is-0.6V, the Faraday efficiency of CO is 97.27%, and the partial current density of CO is 5.3mA/cm²And the compound has good activity, selectivity and stability.

Novel electrode material nano porous AuCu₃The method for researching the performance of the electrocatalytic reduction of the carbon dioxide comprises the following steps:

respectively preparing 40mL of 0.5M KHCO₃Placing the solution in two half cells of an H-type electrolytic cell, and selecting 2 cm-long AuCu₃And @ Au electrode immersed 1cm below the liquid level, platinum sheet as counter electrode, silver/silver chloride electrode as reference electrode, introducing high-purity carbon dioxide into the solution for 30min, testing by CHI 760E electrochemical workstation under magnetic stirring, sampling once every 25min, and analyzing the product by gas chromatography to determine the content of the product. And recovering the catalyst after the reaction is finished.

The present invention will be described in further detail with reference to the following drawings and specific examples.

Example 1

Three-dimensional nano porous AuCu with electrocatalytic reduction carbon dioxide performance₃Preparation of @ Au.

(1) 0.0325g FeCl was added to 40mL deionized water₃Magnetically stirring to obtain solution A;

(2) weighing 40mg of raw material Au₂₀Cu₈₀Adding the solution A, and magnetically stirring for 30 min;

(3) washing with deionized water for several times, and vacuum drying for 6-12 hr.

Example 2

Three-dimensional nano porous AuCu₃Testing the performance of the electrocatalytic reduction carbon dioxide of @ Au.

Respectively preparing 40mL of 0.5M KHCO₃The solution is placed in two half cells of an H-shaped electrolytic cell, and AuCu in the embodiment 1 with the length of 2cm is selected₃Electrode material, clamping with platinum sheet electrode clamp about 0.5cm to make the length below the liquid level 1cm, selecting platinum sheet as counter electrode, and performing silver/silver chloride electroplatingAnd (3) using a reference electrode, introducing high-purity carbon dioxide into the solution for 30min, testing by using a CHI 760E electrochemical workstation under magnetic stirring, sampling every 25min, and analyzing the product by using a gas chromatograph to determine the content of the product. In addition, in order to examine the stability of the electrode material, long-time electrocatalytic reduction of carbon dioxide and I-t reaction for up to 100 hours were performed, the faraday efficiency and current density of CO were examined, and SEM and XRD characterization were performed on the catalyst recovery after the reaction to compare whether the catalyst was stable before and after the reaction.

Example 3

Three-dimensional nano porous AuCu with electrocatalytic reduction carbon dioxide performance₃Preparation of @ Au.

(1) To 228.8mL of deionized water was added 0.1859g of FeCl₃Magnetically stirring and dissolving to obtain a solution A;

(2) weighing 228.8mg of raw material Au₂₀Cu₈₀Adding the solution A, and magnetically stirring for 30 min;

(3) washing with deionized water for several times, and vacuum drying for 6-12 hr.

Example 4

Three-dimensional nano porous AuCu₃Testing the performance of the electrocatalytic reduction carbon dioxide of @ Au.

Respectively preparing 40mL of 0.5M KHCO₃The solution is placed in two half cells of an H-type electrolytic cell, and the AuCu synthesized in the embodiment 3 with the length of 24cm is selected₃Electrode material, clamping about 0.5cm by a platinum sheet electrode clamp, ensuring that the length below the liquid level is 23cm, selecting a platinum sheet as a counter electrode and a silver/silver chloride electrode as a reference electrode, introducing high-purity carbon dioxide into the solution for 30min, testing by a CHI 760E electrochemical workstation under magnetic stirring, sampling once every 25min, and analyzing the product by gas chromatography to determine the content of the product.

The invention develops a three-dimensional nano porous AuCu with a core-shell structure₃@ Au electrode material, the Faraday efficiency of CO was 97.27% at RHE of-0.6V, at which time the partial current density of CO was 5.3mA/cm²And the compound has good activity, selectivity and stability.

FIG. 1 is an SEM photograph of example 1. As can be seen from the figure, the synthesized electrode material is a three-dimensional nano-porous structure and is distributed uniformly, and the ligament size is about 40 nm.

FIG. 2 is the XRD diffraction pattern of example 1. As can be seen from the figure, the synthesized electrode material is AuCu₃There were several weak Au peaks.

Fig. 3 is a TEM photograph of example 1. (a) Is AuCu₃Low magnification TEM photograph of @ Au; (b) a line scan mapping chart for one ligament selected in (a); (c) is AuCu₃High-magnification TEM photograph of @ Au; (c)₁-c₂) An enlarged view of the corresponding lattice fringes in (c). The synthesized electrode material AuCu can be seen from the figure₃The gold-rich material has a core-shell structure, the surface of the gold-rich material is a gold-rich shell, and the corresponding lattice fringes are 0.189nm and correspond to a (200) crystal face of Au; inside is AuCu₃Corresponding to a lattice fringe of 0.208nm for AuCu₃The 200 crystal plane of (1).

FIG. 4 is a photograph of HAADF-STEM of example 1. (a) A high-power transmission image of a selected ligament; (b) is a step of the convex surface in the step (a); (c) is a step position of the concave surface in the step (a). It can be seen from the figure that the ligament surface has positive, negative and saddle-shaped surface curvatures, and there is a high density of atomic steps on the concave-convex curvature surface.

FIG. 5 is a XPS and elemental content chart for example 1. (a) 4f orbital for Au; (b) 2p orbital of Cu; (c) the gold and copper contents of the surface, the interior and the comparison thereof are shown in the order of (a) and (b). As can be seen from the figure, the surface is rich in gold, and the XPS depth analysis test shows that the Cu content is increased along with the depth of the test, thereby proving that the surface is a gold-rich shell and the inside is AuCu₃The core-shell structure of (1).

FIG. 6 is a graph of the performance of the electrocatalytic reduction of carbon dioxide of example 2. (a) Is an LSV diagram; (b) is the divided current density; (c) is the faraday efficiency. The figure shows that the electrode material has good activity and stability in electrocatalytic reduction of carbon dioxide, the Faraday efficiency of CO reaches 97.27% when RHE is-0.6V, and the current density of CO is 5.3mA/cm²。

FIG. 7 is a graph of the stability of electrocatalytic reduction of carbon dioxide for example 2. From the figureIt can be seen that the total current density was maintained at 10mA/cm after 100 hours of the electrocatalytic reduction reaction of carbon dioxide²On the other hand, the faradaic efficiency of CO was maintained at about 94% at this time, and the stability of the electrode material was confirmed to be good.

Fig. 8 is an SEM photograph of example 2 after the electrocatalytic reduction of carbon dioxide for 100h stability test. The synthesized electrode material still maintains a three-dimensional nano porous structure, and the good stability of the synthesized electrode material is fully proved.

FIG. 9 is a graph showing the performance of the electrocatalytic reduction of carbon dioxide in examples 3 to 4. As can be seen from the figure, the current of the synthesized long bulk electrode reaches 37.2mA when the RHE is-0.7V, and the practicability of electrocatalytic reduction of carbon dioxide is promoted.

The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.