CN-118125563-B - Method for electrochemical reduction of nitrate by transition metal nitride and application thereof

Abstract

The invention provides a method for electrochemically reducing nitrate by using transition metal nitride and application thereof, belonging to the field of environmental catalysis, wherein the method for electrochemically reducing nitrate by using transition metal nitride comprises the steps of constructing an electrochemical catalytic system by taking a transition metal nitride catalytic electrode as a working electrode, and under the condition of electrifying, promoting reduction of nitrate in electrolyte by interconversion between metal ions on the surface of the transition metal nitride and zero-valent transition metal generated by electroreduction, wherein the transition metal is iron group transition metal.

Inventors

• LIU RUI
• CHEN NING

Assignees

• 中国科学院生态环境研究中心

Dates

Publication Date

20260508

Application Date

20240307

Claims (6)

1. 1. A method for electrochemically reducing nitrate by using a transition metal nitride, comprising: An electrochemical catalytic system is constructed by taking a transition metal nitride catalytic electrode as a working electrode, under the condition of electrification, the interconversion between metal ions on the surface of the transition metal nitride and zero-valent transition metal generated by electroreduction promotes the reduction of nitrate radical in electrolyte, the applied voltage is-1.3V, and the duration time is 3 hours, wherein the transition metal is iron group transition metal; The iron group transition metal is iron, the transition metal nitride catalytic electrode is an iron nitride catalytic electrode, and iron nitride on the iron nitride catalytic electrode has a (111) crystal structure, wherein the atomic ratio of iron to nitrogen in the crystal structure is 2:1; The transition metal nitride catalytic electrode is obtained by the steps of: Mixing transition metal salt and surfactant to obtain mixed solution, placing the mixed solution in ice-water bath, adding cold reducing agent to make reduction reaction, ageing, separating to obtain transition metal precursor, and mixing Coating the dispersion liquid containing the transition metal precursor on a carrier, and sintering in an ammonia atmosphere to obtain the transition metal nitride catalytic electrode with transition metal nitride distributed on the carrier; The reducing agent is selected from any one of potassium borohydride and sodium borohydride, and the ratio of the reducing agent to the transition metal salt is 4-10:1.
2. 2. The method of claim 1, wherein the transition metal nitride has a size of 100-300nm.
3. 3. The method of claim 1, wherein the sintering temperature is 400-600 ℃, the sintering temperature rise rate is 5-10 ℃ per minute, and the sintering time is 100-150 minutes.
4. 4. The method of claim 1, wherein the transition metal salt is selected from any one of a chlorinated transition metal salt, a sulfuric acid transition metal salt, a nitric acid transition metal salt; the surfactant is polyoxyethylene ether; The ratio of the amount of the transition metal salt to the amount of the surfactant and the amount of the water is 6-10:1-4:2.2 10 5 。
5. 5. The method of claim 1, wherein the carrier is any one of carbon paper, carbon cloth, carbon rod, carbon felt, foamed titanium plate, conductive glass.
6. 6. Use of the method of claim 1 in wastewater treatment.

Description

Method for electrochemical reduction of nitrate by transition metal nitride and application thereof Technical Field The invention belongs to the field of environmental catalysis, and particularly relates to a method for electrochemically reducing nitrate by using transition metal nitride and application thereof, and more particularly relates to a method for electrochemically reducing nitrate by using iron-based transition metal nitride and application thereof. Background Nitrate (NO 3-) is the highest oxidation state of the global nitrogen cycle, accumulating in both industrial and agricultural wastewater and domestic sewage, and its main artificial sources include fertilizer use and fossil fuel combustion. The excessive nitrate can not only seriously affect the water ecological system, such as eutrophication, toxic algal bloom, water anoxia and the like, but also threaten human health by affecting drinking water. The conversion of the existing NO 3- is mainly carried out in two directions, namely (1) reduction into nitrogen (N 2) through a denitrification process of a sewage treatment plant for harmless treatment, and (2) recycling treatment through nitrate/nitrite reductase secreted by microorganisms (reduction into ammonium (NH 4+) through a nitrate dissimilation process), and recovery of ammonium nitrogen through combining processes such as air stripping, ion exchange, struvite precipitation and the like. The metal catalyst commonly used for NO 3- reduction is a supported Cu-based catalyst, a doped metal alloy catalyst and a noble metal catalyst, and the preparation cost is high because the used metal is noble metal, and the increasing production of NO 3- cannot be met, so that the development of the NO 3- reduction catalyst based on cheap metal has practical significance. Although transition metals have some applications in the design of NO 3- reduction catalysts, most of them have better properties as the second metal element doped in alloys and their oxides, which are not the main elements providing active sites, and more are adjusting the binding energy and D-band center of the metal, thus improving the adsorption and dissociation of the material to NO 3- and reaction intermediates. And the catalyst taking the transition metal as the main component is relatively slow in NO 3- reduction, and the ordered mesoporous carbon loaded nano zero-valent iron has only 65 percent conversion rate to 50mg/L NO 3- in the electrolyte in the electrocatalytic process of 24 hours. The nitrogen doped graphite carbon encapsulated iron nanoparticles had only 83% conversion of 50mg/L NO 3- in the electrolyte for 24 hours. The polymer bead loaded nZVI 24 hours gave 80% conversion of 50mg/L NO 3- in the electrolyte. Although the nano enzyme catalyst FeNPs@MXene realizes 97.8% of NO 3- conversion rate, the selectivity of the target product NH 4+ is still low and is only 76.8%. in addition, many reported transition metal catalysts have problems of poor stability and corrosion resistance. Disclosure of Invention Aiming at the technical problems, the invention provides a method for electrochemically reducing nitrate by using transition metal nitride and application thereof, so as to at least partially solve the technical problems. As a first aspect of the present invention, there is provided a method for electrochemically reducing nitrate by using a transition metal nitride, comprising: An electrochemical catalytic system is constructed by taking a transition metal nitride catalytic electrode as a working electrode, and under the condition of electrifying, the interconversion between metal ions on the surface of the transition metal nitride and zero-valent transition metal generated by electroreduction promotes the reduction of nitrate in electrolyte, wherein the transition metal is iron group transition metal. As a second aspect of the invention, the invention provides the use of the above method in sewage treatment. In the embodiment of the invention, the prepared transition metal nitride catalytic electrode is used as a working electrode to construct an electrochemical catalytic system, and under the condition of electrification, the working electrode generates transition metal reduction reaction, nitrate radical reduction reaction and hydrogen evolution reaction, wherein the interconversion between metal ions on the surface of the transition metal nitride and zero-valent transition metal generated by electroreduction promotes the reduction of nitrate radical in the electrolyte, and the nitrate radical reduction reaction is used as the main reaction, so that the nitrate radical conversion rate, conversion speed and product selectivity are improved. Meanwhile, the transition metal nitride is relatively stable and not easy to corrode, and can stably operate for a long time. The method reduces nitrate by transition metal nitride electrochemistry, and is convenient to operate. In addition, the method for electrochemicall