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CN-121976227-A - For NO2RR CoNi alloy catalyst, preparation and application method

CN121976227ACN 121976227 ACN121976227 ACN 121976227ACN-121976227-A

Abstract

A CoNi alloy catalyst for NO 2 RR is prepared from three-dimensional porous foam titanium as conducting substrate, active layer of CoNi alloy nanoparticles carried on said substrate, natural oxide/hydroxy layer on surface of active layer to form "alloy core-oxide layer shell" structure, and features that the precursor liquid containing Co2 + and Ni2 + is prepared, the foam titanium substrate is step-by-step ultrasonic cleaned and activated, and Co2 + and Ni2 + are synchronously reduced and alloyed by constant-current electrodeposition in said precursor liquid, and finally cleaned and dried. The design enables the catalyst to realize the effective unification of high catalytic activity, high ammonia selectivity and excellent structural stability through the coordination of CoNi solid solution alloy design, core-shell interface regulation and control and a three-dimensional self-supporting framework.

Inventors

  • HE SISI
  • LI YUAN
  • ZHONG XIAOHUA

Assignees

  • 武汉市碳翁科技有限公司

Dates

Publication Date
20260505
Application Date
20260119

Claims (10)

  1. 1. A CoNi alloy catalyst for NO 2 RR is characterized by comprising a conductive substrate, a CoNi alloy nanoparticle layer supported on the surface of the conductive substrate, and an oxidation/hydroxyl layer formed on the CoNi alloy nanoparticle layer by natural oxidation.
  2. 2. The CoNi alloy catalyst for NO 2 RR as defined in claim 1, wherein the conductive substrate is foamed titanium, and the CoNi alloy nanoparticle layer is in a CoNi solid solution phase, and the atomic mole ratio of Co to Ni is 60:40-90:10.
  3. 3. A CoNi alloy catalyst for NO 2 RR as defined in claim 2, wherein the oxide/hydroxy layer comprises Co-O and Ni-O species, and the oxide/hydroxy layer has a thickness of 5nm to 50nm.
  4. 4. A method for preparing a CoNi alloy catalyst for NO 2 RR as defined in claim 1,2 or 3, wherein the method comprises the following steps: S1, dissolving soluble cobalt salt and soluble nickel salt in water to obtain a mixed salt solution containing cobalt ions and nickel ions, and then adding conductive salt or complexing agent into the mixed salt solution to obtain a precursor solution; S2, firstly placing the titanium foam in an organic solvent for ultrasonic cleaning, then taking out the titanium foam, placing the titanium foam in a strong acid aqueous solution for ultrasonic cleaning again, and obtaining a pretreated conductive substrate; S3, taking the precursor solution as electrolyte, taking the conductive substrate as a working electrode, performing electrochemical deposition in a three-electrode electrochemical system by adopting a constant current mode, synchronously reducing cobalt ions and nickel ions in the precursor solution on the surface of the conductive substrate to form a CoNi alloy nano particle layer, taking out the conductive substrate loaded with the CoNi alloy nano particle layer after the electrochemical deposition is completed, and then cleaning and drying the conductive substrate to finally obtain the catalyst.
  5. 5. The method of preparing a catalyst according to claim 4, wherein in S1, the molar concentration ratio of cobalt ions to nickel ions in the mixed salt solution is 60:40-90:10.
  6. 6. The method for preparing a catalyst according to claim 5, wherein in S1, when adding a conductive salt to the mixed salt solution is selected, the conductive salt is NH 4 Cl, the addition amount of NH 4 Cl is 3.5g-4.5g per 50mL of the mixed salt solution, and when adding a complexing agent to the mixed salt solution, the complexing agent is citric acid, and the addition amount of citric acid is 0.8g-1g per 50mL of the mixed salt solution.
  7. 7. The method for preparing the catalyst according to claim 4, wherein in the step S2, the titanium foam is placed in an organic solvent for ultrasonic cleaning for 18-22 min, the organic solvent is ethanol, the titanium foam is placed in a strong acid aqueous solution for ultrasonic cleaning for 18-22 min, the strong acid aqueous solution is hydrochloric acid solution, and the concentration of the hydrochloric acid solution is 2-6 mol/L.
  8. 8. The method of preparing a catalyst according to claim 4, wherein the constant current mode has a current density of 0.8A/cm2 to 1.2A/cm2 and the electrochemical deposition time is 250S to 350S in S3.
  9. 9. The method for preparing a catalyst according to claim 8, wherein in the step S3, the three-electrode electrochemical system comprises a working electrode, a counter electrode and a reference electrode, wherein the counter electrode is a carbon rod, and the reference electrode is an Ag/AgCl electrode filled with saturated potassium chloride.
  10. 10. A method for using the CoNi alloy catalyst for NO 2 RR as set forth in claim 1, 2 or 3, wherein the method comprises the step of reducing nitrite to ammonia by using the catalyst as a working electrode and performing potentiostatic or galvanostatic electrolysis in an alkaline electrolyte containing nitrite ions.

Description

CoNi alloy catalyst for NO 2 RR, preparation and application method Technical Field The invention relates to a catalyst and preparation and application methods thereof, belongs to the field of preparing ammonia by electrocatalytic nitrite reduction, and particularly relates to a CoNi alloy catalyst for NO 2 RR, and preparation and application methods thereof. Background The ammonia is used as an important chemical raw material and a clean energy carrier, and the electrocatalytic nitrite reduction reaction (NO 2 RR) is a key technical route for preparing ammonia in a green way, and has important application value in the fields of environmental management and sustainable energy. In the prior art, the catalyst for NO 2 RR is usually based on noble metals and transition metal single metal systems such as iron, cobalt, nickel and the like. However, the single metal catalyst is limited by the single intrinsic electronic structure, so that the efficient adsorption, deep hydrogenation and competitive reaction inhibition of nitrite (NO 2-) are difficult to cooperatively realize, the problems of low activity and poor selectivity are generally existed, the structure corrosion and active component dissolution are easy to occur under the high current density, and the stability is insufficient. In order to solve the above problems, the prior art attempts to improve by means of alloying, defect engineering and the like, and improves part of the performance of the catalyst to a certain extent. For example, the adsorption and hydrogenation capacity can be improved by alloying the control electronics, or the number of active sites can be increased by morphological optimization, but these improvements still have significant limitations in that most schemes focus on optimization of only a single performance dimension, failing to form a systematic design strategy, either to increase activity but to suppress HER competition, or to improve selectivity but to sacrifice long-term stability, and always fail to achieve efficient unification of high activity, high selectivity and high stability. The Chinese patent application with the application number of CN202210185440.3 and the application date of 2022.02.28 discloses an ultrathin iron phosphide nano-array electrocatalyst taking a titanium sheet as a substrate, and a preparation method and application thereof. The design has the advantages that the substrate-active layer integrated structure is adopted, the nano array morphology provides high specific surface area and abundant active sites, the preparation process is simple, the raw material cost is low, and certain catalytic activity is shown in the nitrite reduction reaction. However, the design still does not break through the existing bottleneck, the active component is single metal phosphide, the electronic structure is single, the deep hydrogenation kinetics is limited, the ammonia selectivity lifting space is limited, a natural oxide layer is easy to form on the surface of FeP, the oxide layer can reduce the utilization rate of active sites and can not effectively inhibit the hydrogen gas precipitation reaction, the interface combination of the FeP active layer and a titanium sheet substrate depends on the physical-chemical action, the problems of active layer stripping, phosphorus element dissolution and the like are easy to occur when the high-current density (> 300 mA/cm < 2 >) is operated for a long time, and the stability is insufficient. Still has the following drawbacks: The effective unification of high activity, high selectivity and high stability is not realized. The disclosure of this background section is only intended to increase the understanding of the general background of the application and should not be taken as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art. Disclosure of Invention The invention aims to overcome the defect that the catalyst in the prior art cannot realize high activity, high selectivity and high stability and effectively unify, and provides a CoNi alloy catalyst for NO 2 RR, which can realize high activity, high selectivity and high stability and effectively unify, and a preparation method and an application method thereof. In order to achieve the above object, the technical solution of the present invention is: A CoNi alloy catalyst for NO 2 RR, the catalyst comprising a conductive substrate, a CoNi alloy nanoparticle layer supported on a surface of the conductive substrate, and an oxide/hydroxy-based layer formed by natural oxidation on the CoNi alloy nanoparticle layer. The conductive substrate is foam titanium, and the CoNi alloy nano particle layer is a CoNi solid solution phase, wherein the atomic mole ratio of Co to Ni is 60:40-90:10. The oxidation/hydroxyl base layer comprises Co-O and Ni-O species, and the thickness of the oxidation/hydroxyl base layer is 5nm-50nm. A method for prepar