CN110655654A

CN110655654A - Preparation of two-dimensional layered cobalt-based metal organic framework (Co-MOF) electrode material and research on oxygen evolution performance

Info

Publication number: CN110655654A
Application number: CN201910881402.XA
Authority: CN
Inventors: 谢爱娟; 张洁; 多晓晓; 刘忠翔; 常珈宁; 陶祥; 张江辉; 罗士平
Original assignee: Changzhou University
Current assignee: Changzhou University
Priority date: 2019-09-18
Filing date: 2019-09-18
Publication date: 2020-01-07

Abstract

The invention belongs to the technical field of novel energy, and particularly relates to preparation of a two-dimensional layered Co-MOF electrode material with remarkably improved water oxidation performance and oxygen evolution performance research. The invention prepares a two-dimensional layered Co-MOF electrode material by a simple and mild hydrothermal method, and then uses the prepared electrode material for the oxidation performance research of electrolyzed water, comprising the following steps: preparing a two-dimensional layered Co-MOF electrode material by a hydrothermal method; and (3) researching the oxygen evolution performance of the prepared electrode material. The invention has the beneficial effects that: the two-dimensional layered Co-MOF electrode material has good stability, good oxygen evolution reaction performance and wide application prospect in the technical field of novel energy.

Description

Preparation of two-dimensional layered cobalt-based metal organic framework (Co-MOF) electrode material and research on oxygen evolution performance

Technical Field

The invention belongs to the technical field of novel energy, and particularly relates to preparation of a two-dimensional layered Co-MOF electrode material with remarkably improved water oxidation performance and oxygen evolution performance research.

Background

With the development of science and technology, the demand of people for energy is continuously increased, and people are forced to find a clean, efficient and renewable new-generation energy conversion and storage system. Recently, scientists have made new research advances on water that is ubiquitous in everyday life. Various efficient and rapid hydrogen production methods such as photolysis of water, power generation and water supply electrolysis, nuclear energy cracking, steam reforming and the like are explored at present. The central process of these studies is the Oxygen Evolution Reaction (OER), which often occurs at the interface between phases (solid, liquid, gas). Therefore, in order to promote the progress of the oxygen evolution reaction, thereby improving the activity of the oxygen evolution reaction and improving the energy efficiency, it is urgent to develop an electrode material having a high catalytic electrolytic water reaction performance.

At present, it is popular to research the preparation of electrode materials by using porous Metal Organic Frameworks (MOFs) as complexes, and the materials have large specific surface area, uniform structure and adjustable composition structure, which is caused by variable metal centers and organic ligands. For the selection of metal centers for MOF materials, almost all metals in the periodic table can be covered, but Co, Cu, etc. are more commonly used. The metal ions act as catalytic active centers throughout the metal organic framework precursor material, while the majority of the organic ligands act as micro-channel frameworks throughout the MOF material. The metal ions of the organic ligands have many active centers, which promote the propagation and diffusion of multiple channels during reaction and interaction. Meanwhile, the framework of the MOF has a redundant active site structure, so that a proper place is provided for synthesizing an electrocatalyst material with excellent performance.

Disclosure of Invention

The invention provides a simple and mild two-dimensional layered Co-MOF electric material preparation method based on the reasons, and then the prepared electrode material is used for oxidation performance research of electrolyzed water. The preparation method of the two-dimensional layered Co-MOF electrode material comprises the following specific steps:

(1) 128mL of DMF (N, N-dimethylformamide), 8mL of ethanol and 8mL of deionized water are accurately measured in a 250mL beaker, and a disposable plastic film and a rubber band are used for sealing to prevent the DMF and the ethanol from volatilizing. After mixing uniformly, 0.4984g (3 mmol) of terephthalic acid (H2 BDC) is weighed, then under the ultrasonic condition (40 KHz), 0.7472g (3 mmol) of cobalt acetate tetrahydrate (C4H6CoO4.4H2O) is added, and the mixture is transferred to a hydrothermal kettle;

(2) and placing the hydrothermal kettle in an oven for reaction, taking out the hydrothermal kettle which is cooled to room temperature after the reaction is finished, pouring out the generated metal organic framework, cooling and carrying out centrifugal treatment for 2-3 times, hanging the residual solid in the centrifugal tube into a watch glass by using distilled water and a glass rod, and drying in a constant-temperature oven at 60 ℃ to remove water. And taking out the culture dish after the product is completely dried, grinding uniformly, and marking as Co-MOF.

Further, in the step (1), the volume ratio of DMF, ethanol and deionized water is 16: 1: 1; the molar ratio of the organic ligand terephthalic acid to the tetrahydrate cobalt acetate is 1: 1.

further, the hydrothermal reaction temperature of the solution in the step (2) is 140 ℃; the reaction time was 12, 24, 48 hours.

Further, the time for cooling the hydrothermal reaction kettle to room temperature in the step (2) is 8 ~ 10 hours.

Further, in the step (2), the drying time in the oven at the constant temperature of 60 ℃ is 4 ~ 6 hours.

The invention has the beneficial effects that:

the two-dimensional layered Co-MOF electrode material prepared by the method has good stability, good oxygen evolution reaction performance and wide application prospect in the technical field of novel energy.

Drawings

The invention will be further explained with reference to the drawings.

FIG. 1 is XRD pattern of two-dimensional layered Co-MOF electrode material in example 1

FIG. 2 is an SEM picture of a two-dimensional layered Co-MOF electrode material prepared in example 1

FIG. 3 is a comparison of oxygen evolution performance of two-dimensional layered Co-MOF electrode material and Cu-MOF in comparative example 2.

Detailed Description

The invention will now be further illustrated by reference to specific examples, which are intended to be illustrative of the invention and are not intended to be a further limitation of the invention.

Example 1:

the preparation method of the composite electrode material comprises the following steps:

(2) the hydrothermal kettle is reacted in an oven at 140 ℃ for 24 hours, the hydrothermal kettle after the reaction is finished and cooled is taken out, a generated metal organic framework is poured out, the hydrothermal kettle is cooled to room temperature and is subjected to centrifugal treatment for 2 to 3 times, distilled water and a glass rod are used for scraping residual solids in a centrifugal tube into a watch glass and then the watch glass is placed in a constant-temperature oven at 60 ℃ for drying so as to remove moisture in the residual solids, and after a product is completely dried, the product is uniformly ground and packaged for later use, wherein crystal faces of (200), (001), (201) and (201) of the Co-MOF are proved by an XRD (X-ray diffraction) diagram of the prepared Co-MOF, four obvious diffraction peaks of less than 10 degrees and about 15 degrees ~ 20 degrees are respectively corresponding to the Co-MOF, and the crystal faces of (2), (201) and (201) of the Co-MOF are shown in a scanning electron microscope diagram of the Co-.

Example 2:

the electrode material prepared in example 1 was used for water electrolysis by placing a Co-MOF modified electrode in 0.1mol/L KOH saturated with O2, scanning at 5mV/s, rotating at 1600rpm, potential window of 0 ~ 1.0.0V, and OER performance testing with sensitivity of 1X 10-3.

Comparative example 1:

changing the reaction time in the constant-temperature oven in the step (2) of the example 1 into 12h and 48h, controlling the residual conditions to be unchanged, synthesizing other two Co-MOF materials, and carrying out OER performance test. Test method, test conditions were identical to those of example 2. The test results showed that the overpotential at 10mA/cm2 for Co-MOF prepared with a reaction time of 24 hours was 480mV, which was lower than the reaction times of 12h (570 mV) and 48h (520 mV). The Co-MOF electrode material prepared under the condition that the hydrothermal reaction time is 24 hours has better OER performance.

Comparative example 2:

and (3) comparing the OER performance of the Co-MOF electrode material and the Cu-MOF electrode material, wherein the Cu-MOF preparation method is completely consistent with the Co-MOF preparation method, and only the initial reactant is changed from cobalt acetate to copper acetate. The test method and test conditions were the same as in example 2. FIG. 3 is a LSV graph of two electrode materials, Co-MOF and Co-MOF, from which it is clear that the overpotential of the Co-MOF electrode material at 10mA/cm2 is 470 mV, which is significantly lower than 730mV of Cu-MOF for OER reaction, indicating that the electrocatalytic performance is significantly better than that of the Cu-MOF electrode material. The method shows that the selection of metal ions can cause certain influence in the synthesis process of the MOF material, and the two-dimensional layered Co-MOF electrode material prepared by the method has better stability, good oxygen evolution reaction performance and wide application prospect in the technical field of novel energy sources.

Claims

1. A preparation method and oxygen evolution performance research of a two-dimensional layered Co-MOF electric material are characterized by comprising the following main steps:

(1) accurately measuring 128mL of DMF (N, N-dimethylformamide), 8mL of ethanol and 8mL of deionized water in a 250mL beaker, sealing by using a disposable plastic film and a rubber band to prevent DMF and ethanol from volatilizing, weighing 0.4984g (3 mmol) of terephthalic acid (H2 BDC) after uniformly mixing, then adding 0.7472g (3 mmol) of cobalt acetate tetrahydrate (C4H6CoO4.4H2O) under the ultrasonic condition (40 KHz), and transferring to a hydrothermal kettle;

(2) and (3) placing the hydrothermal kettle in an oven for reaction, taking out the hydrothermal kettle which is cooled to room temperature after the reaction is finished, pouring out the generated metal organic framework, cooling and centrifuging for 2-3 times, scraping the residual solid in the centrifugal tube into a watch glass by using distilled water and a glass rod, drying in a constant-temperature oven at 60 ℃ to remove water, taking out the watch glass after the product is completely dried, grinding uniformly, and marking as Co-MOF.

2. The preparation method and the oxygen evolution performance research of the two-dimensional layered Co-MOF electric material according to claim 1, wherein the volume ratio of DMF, ethanol and deionized water in the step (1) is 16: 1: 1; the molar ratio of the organic ligand terephthalic acid to the tetrahydrate cobalt acetate is 1: 1.

3. the preparation method and the oxygen evolution performance research of the two-dimensional layered Co-MOF electric material according to claim 1, wherein the hydrothermal reaction temperature of the solution in the step (2) is 140 ℃; the reaction time was 12, 24, 48 hours.

4. The preparation method and the oxygen evolution performance research of the two-dimensional layered Co-MOF electric material according to claim 1, wherein the time for cooling the hydrothermal reaction kettle to room temperature in the step (2) is 8 ~ 10 hours.

5. The preparation method and the oxygen evolution performance research of the two-dimensional layered Co-MOF electric material according to claim 1, wherein the drying time in the oven at the constant temperature of 60 ℃ in the step (2) is 4 ~ 6 hours.