Co-coated Ni3S2-x catalyst with monatomic Co anchored in S vacancy and preparation method and application thereof

Abstract

The invention discloses a Co-coated Ni3S2-x catalyst with monatomic Co anchored in S vacancy and a preparation method and application thereof, and the synthesis method comprises the following steps: adding thiourea into deionized water, fully dissolving and uniformly dispersing, immersing foamed nickel into the mixed solution, and preparing Ni3S2 through a hydrothermal method. The preparation method comprises the following steps: carrying out argon plasma bombardment on Ni3S2 to prepare Ni3S2-x containing S vacancies, dipping Ni3S2-x in an aqueous solution containing Co (NO3) 2.6 H2O, and calcining in an H2 / Ar atmosphere to anchor monatomic Co on the S vacancies to prepare Co (at) Ni3S2-x. The Co-coated Ni3S2-x catalyst prepared by the invention can be used for converting PET derivative ethylene glycol into high-value formic acid at normal temperature and normal pressure.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrocatalytic materials, and particularly relates to a Co@Ni3S 2-x catalyst, a preparation method and application thereof. BACKGROUND

[0002] In recent years, the demand for plastics has rapidly increased and is expected to continue to grow in the future. However, only about 26% of plastic waste is recycled, and the rest is transported to landfills, illegal dumping sites or abandoned, with 4.8-12.7 million tons of plastic entering the ocean every year. Due to factors such as weathering, degradation and microbial metabolism, plastics present in the environment will gradually decompose into various forms, including spheres, fragments and fibers, which are referred to as microplastics (MPs). Polyethylene terephthalate (PET) is one of the most widely used plastics, commonly used in beverage and drinking water bottles. From 2016 to 2021, the compound annual growth rate of PET will reach 21.93 million tons. It is worrying that PET microplastics are widely distributed and can be found in all marine environments and some urban coastal sediment environments. Generally, humans can ingest these particles through food, air and skin contact, causing serious harm to living organisms, such as oxidative stress, cytotoxicity and chronic inflammation. Therefore, it is urgent to seek an appropriate method to recycle waste PET plastic waste.

[0003] PET waste plastics can be hydrolyzed into terephthalic acid (TPA) and ethylene glycol (EG) in an alkaline aqueous solution, and EG can be used to convert into high-value-added products. Electrocatalytic methods can upgrade EG to formic acid or glycolic acid under mild conditions. Ni3S2 electrocatalysts have certain performance in electrocatalytic oxidation of PET, but their selectivity and Faraday efficiency still need to be improved. The electronic structure of Ni3S2 can be adjusted through the synergistic effect of single-atom doping and S vacancies, which can improve the performance of electrocatalytic PET oxidation and has important guiding significance for electrocatalytic PET waste plastic upgrading. SUMMARY

[0004] In view of the problems in the prior art, the application is designed to provide a Co@Ni3S 2-x catalyst and a preparation method and application thereof, which are specifically implemented by the following technical solutions:

[0005] A Co@Ni3S 2-x catalyst, which is a thin sheet structure composed of S vacancies introduced by argon plasma bombardment of Ni3S2 and atomically anchored Co.

[0006] A Co@Ni3S2-x The method for preparing the catalyst includes the following steps:

[0007] 1) Thiourea was dissolved in deionized water and dispersed evenly. Then, nickel foam was immersed in the thiourea solution to prepare Ni3S2 by hydrothermal method.

[0008] 2) Ni3S2 rich in S vacancies was prepared by bombarding with argon plasma. 2-x ;

[0009] 3) Ni3S 2-x Co@Ni3S was prepared by impregnation in an aqueous solution containing Co(NO3)2·6H2O followed by calcination under an H2 / Ar atmosphere. 2-x ;

[0010] Further, step 1) specifically involves dissolving 0.2-0.6 mmol of thiourea in 25 mL of deionized water and uniformly dispersing it using ultrasonic oscillation at a power of 90 W for 10-50 min. Then, nickel foam (3 × 2 cm) is immersed in the thiourea solution to prepare Ni3S2 via a hydrothermal method at a temperature of 120-140 °C for 12-20 h.

[0011] Further, step 2) specifically involves preparing Ni3S2 rich in S vacancies by bombarding it with argon plasma. 2-x The power of argon plasma bombardment is 80-120W, and the bombardment time is 5-15min.

[0012] Further, step 3) specifically involves: applying Ni3S... 2-x Co@Ni3S was prepared by impregnation in an aqueous solution containing Co(NO3)2·6H2O (concentration of 0.5-1.5 mmol / L) for 3 h, followed by calcination under an H2 / Ar atmosphere. 2-x The calcination temperature is 300-400℃, the heating rate is 5℃ / min, and the calcination time is 1-3h. The material prepared by calcination for 2h is Co@Ni3S. 2-x The materials prepared by calcination for 1 and 3 hours were Co1@Ni3S, respectively. 2-x and Co 3@Ni3S 2-x .

[0013] The Co@Ni3S obtained above 2-x Application of catalysts in electrocatalytic PET oxidation.

[0014] The raw material used in the preparation method is low in price and easy to obtain, the reaction condition is mild, the prepared catalyst has a low overpotential of 1.32V in 1M KOH+0.16M ethylene glycol electrolyte, 100mA / cm 2 and can efficiently oxidize PET derivatives to prepare formic acid, thereby providing an efficient electrocatalytic solution for plastic recycling and high-value conversion. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The XRD pattern of the material Co@Ni3S 2-x prepared in Example 1;

[0016] Figure 2 The SEM pattern of the material Co@Ni3S 2-x prepared in Example 1;

[0017] Figure 3 The spherical aberration electron microscope pattern of the material Co@Ni3S 2-x prepared in Example 1;

[0018] Figure 4 The TEM and Mapping pattern of the material Co@Ni3S 2-x prepared in Example 1;

[0019] Figure 5 The EPR pattern of the material Co@Ni3S 2-x prepared in Example 1;

[0020] Figure 6 The LSV pattern of the material Co@Ni3S 2-x prepared in Example 1 in 1M KOH+0.16M ethylene glycol;

[0021] Figure 7 The LSV pattern of the material Co 1@Ni3S 2-x prepared in Example 2 in 1M KOH+0.16M ethylene glycol;

[0022] Figure 8 The LSV pattern of the material Co 3@Ni3S 2-x prepared in Example 3 in 1M KOH+0.16M ethylene glycol;

[0023] Figure 9 The LSV pattern of the material Ni3S 2-x without anchoring Co atoms in 1M KOH+0.16M ethylene glycol;

[0024] Figure 10 The LSV pattern of the material Ni3S2 in 1M KOH+0.16M ethylene glycol;

[0025] Figure 11 Co@Ni3S material prepared in Example 1 2-x LSV plot in 1M KOH;

[0026] Figure 12 Co@Ni3S material prepared in Example 1 2-x NMR after electrolysis at 1.40V potential for 9h in electrolyte of 1M KOH + 0.16M ethylene glycol 1 H spectrum;

[0027] Figure 13 PET oxidation performance test plot for Example 4. DETAILED DESCRIPTION

[0028] The present application is further described in the following by specific examples, so as to better understand the technical solutions.

[0029] Example 1

[0030] 0.4mmol of thiourea was dissolved in 25mL of deionized water and uniformly dispersed by ultrasonic oscillation, the ultrasonic power was 90W and the ultrasonic time was 50min. Then the foamed nickel (3x2cm) was immersed in the thiourea solution, and Ni3S2 was prepared by hydrothermal method, the hydrothermal temperature was 130℃ and the hydrothermal time was 16h.

[0031] The Ni3S2 was prepared by argon plasma bombardment to obtain S-vacancy-rich Ni3S 2-x , the power of argon plasma bombardment was 100W and the bombardment time was 10min.

[0032] The Ni3S 2-x was immersed in an aqueous solution containing Co(NO3)2.6H2O, the concentration of Co(NO3)2.6H2O solution was 1mmol / L, the immersion time was 3h, and then calcined under H2 / Ar atmosphere to prepare Co@Ni3S 2-x , the calcination temperature was 350℃, the heating rate was 5℃ / min, the calcination time was 2h, and the prepared material was Co@Ni3S 2-x .

[0033] As shown in Figure 1 , the prepared Co@Ni3S 2-x matched the standard card (JCPDS No. 44-1418) of Ni3S2 and had no impurity peak.

[0034] As shown in Figure 2 , the Co@Ni3S 2-x material prepared in the example had a flake structure.

[0035] AsFigure 3 and Figure 4 As shown, Co single atoms are uniformly dispersed in Ni3S. 2-x Surface, TEM, and mapping tests further confirmed the presence of Co single atoms in Ni3S. 2-x The surface is evenly dispersed.

[0036] like Figure 5 As shown, the peak appearing at g = 2.003 is Ni3S 2-x The peak of the upper S vacancy, while Co@Ni3S 2-x The peak at g = 2.003 weakens significantly, confirming that the Co single atom has been anchored to Ni3S. 2-x On the empty S position.

[0037] Example 2

[0038] 0.2 mmol of thiourea was dissolved in 25 mL of deionized water and uniformly dispersed by ultrasonic oscillation at a power of 90 W for 40 min. Then, nickel foam (3 × 2 cm) was immersed in the thiourea solution to prepare Ni3S2 via a hydrothermal method at 120 °C for 12 h.

[0039] Ni3S2 rich in S vacancies was prepared by bombardment with argon plasma. 2-x The argon plasma bombardment power was 80W, and the bombardment time was 5 minutes.

[0040] Ni3S 2-x Co@Ni3S was prepared by impregnation in an aqueous solution containing Co(NO3)2·6H2O (0.5 mmol / L) for 3 hours, followed by calcination under an H2 / Ar atmosphere. 2-x The calcination temperature was 300℃, the heating rate was 5℃ / min, and the calcination time was 1h. The materials prepared were Co1@Ni3S. 2-x .

[0041] Example 3

[0042] 0.6 mmol of thiourea was dissolved in 25 mL of deionized water and uniformly dispersed by ultrasonic oscillation at a power of 90 W for 30 min. Then, nickel foam (3 × 2 cm) was immersed in the thiourea solution to prepare Ni3S2 via a hydrothermal method at 140 °C for 20 h.

[0043] Ni3S2 rich in S vacancies was prepared by bombardment with argon plasma. 2-xThe argon plasma bombardment power was 120W, and the bombardment time was 15min.

[0044] Ni3S 2-x Co@Ni3S was prepared by impregnation in an aqueous solution containing Co(NO3)2·6H2O (1.5 mmol / L) for 3 h, followed by calcination under an H2 / Ar atmosphere. 2-x The calcination temperature was 400℃, the heating rate was 5℃ / min, and the calcination time was 3h. The material prepared by calcination for 3h was Co3@Ni3S. 2-x .

[0045] Application Example 1

[0046] Electrochemical workstation with three electrode system (CHI 760E) was used to study Ni3S2 and Ni3S... 2-x Co1@Ni3S 2-x Co@Ni3S 2-x and Co 3@Ni3S 2-x The performance was tested using C rods, Ni3S2, and Ni3S as electrodes. 2-x Co 1@Ni3S 2-x Co@Ni3S 2-x and Co 3@Ni3S 2-x The Hg / HgO electrode was used as the working electrode, and the electrolyte was 1M KOH + 0.16M ethylene glycol. All potentials were calibrated relative to the reversible hydrogen electrode (RHE) using the following calculations: E RHE =E Hg / HgO +0.098V +0.059pH, all polarization curves were corrected with 90% iR compensation.

[0047] like Figure 6 As shown, at room temperature, the electrolyte is 1M KOH + 0.16M ethylene glycol, and the current density is 100 mA / cm². 2 At that time, the Co@Ni3S prepared in Example 1 of the present invention 2-x The potential is 1.32V.

[0048] like Figure 7 As shown, at room temperature, the electrolyte is 1M KOH + 0.16M ethylene glycol, and the current density is 100 mA / cm². 2 At that time, the Co1@Ni3S prepared in Example 2 of the present invention 2-x The potential is 1.37V.

[0049] like Figure 8 As shown, at room temperature, the electrolyte is 1M KOH + 0.16M ethylene glycol, and the current density is 100 mA / cm².2 At the same time, the Co3@Ni3S prepared in Example 3 of the present invention 2-x The potential is 1.35V.

[0050] like Figure 9 As shown, at room temperature, the electrolyte is 1M KOH + 0.16M ethylene glycol, and the current density is 100 mA / cm². 2 At that time, Ni3S rich in S vacancies and unanchored Co atoms 2-x The potential is 1.40V;

[0051] like Figure 10 As shown, at room temperature, the electrolyte is 1M KOH + 0.16M ethylene glycol, and the current density is 100 mA / cm². 2 At that time, the potential of Ni3S2 without argon plasma bombardment and Co atom anchoring was 1.44V.

[0052] Application Example 2

[0053] Electrochemical workstation with three electrode system (CHI 760E) was used to study Ni3S2 and Ni3S... 2-x Co1@Ni3S 2-x Co@Ni3S 2-x and Co 3@Ni3S 2-x The performance was tested using C rods, Ni3S2, and Ni3S2 electrodes. 2-x Co 1@Ni3S 2-x Co@Ni3S 2-x and Co 3@Ni3S 2-x The Hg / HgO electrode was used as the working electrode, and the electrolyte was 1M KOH. All potentials were calibrated relative to the reversible hydrogen electrode (RHE) using the following calculations: E RHE =E Hg / HgO +0.098V +0.059pH, all polarization curves were corrected with 90% iR compensation.

[0054] like Figure 11 As shown, at room temperature, with an electrolyte of 1M KOH, when the current density is 100 mA / cm² 2 At that time, the Co@Ni3S described in this invention 2-x The potential is 1.58V.

[0055] Application Example 3

[0056] Electrochemical workstation with three electrode system (CHI 760E) was used to study Co@Ni3S 2-x The performance was tested using a C rod as the counter electrode and a Co@Ni3S electrode as the working electrode. 2-xThe reference electrode is Hg / HgO, and the electrolyte is 1M KOH + 0.16M ethylene glycol. All potentials are calibrated relative to the reversible hydrogen electrode (RHE) using the following calculations: E RHE =E Hg / HgO +0.098V +0.059pH, electrolyzed at 1.35V for 9 hours, and then the electrolyzed solution was subjected to nuclear magnetic resonance (NMR) analysis. 1 H) test.

[0057] like Figure 12 As shown, with the increase of electrolysis time, the characteristic peak of ethylene glycol gradually weakens, while the characteristic peak of formic acid gradually strengthens, indicating that ethylene glycol is gradually converted into formic acid during the electrolysis process.

[0058] Application Example 4

[0059] The polyethylene terephthalate (PET) hydrolysate was obtained by treating waste PET plastic bottles under alkaline conditions. The collected waste PET plastic bottles were washed, cut into small pieces, and dried. Then, 12g of the dried waste plastic bottle pieces were added to 200mL of KOH solution (2M), and the mixture was heated with magnetic stirring in an oil bath at 90°C for 100h.

[0060] like Figure 13 As shown, an electrochemical workstation (CHI 760E) with a two-electrode system was used to study Co@Ni3S. 2-x The oxidation performance of PET under real-world conditions was tested, with the working anode electrode being Co@Ni3S. 2-x The cathode working electrode is a platinum-plated titanium felt (Pt / Tifelt), the reference electrode is Hg / HgO, the electrolyte introduced at the anode is 1M KOH + 0.16M ethylene glycol, the electrolyte introduced at the cathode is 1M KOH, and the flow rate is 5 mL / min. -1 Electrolysis was performed at a potential of 1.70V for 6 hours. 120mL of H2 was obtained from the cathode, and 0.32g of formic acid was obtained from the anolyte after recrystallization and filtration.

Claims

1. Co@Ni3S with single-atom Co anchored at S vacancy 2-x Catalyst characterized in that, The catalyst is a thin sheet structure composed of S vacancies introduced by argon plasma bombardment of Ni3S2 and anchoring atomic-level Co.

2. Co@Ni3S with single-atom Co anchored at S vacancy 2-x Process for the preparation of a catalyst, characterized in that The method comprises the following steps: 1) Dissolving thiourea in deionized water and uniformly dispersing it, then immersing foamed nickel into the thiourea solution to prepare Ni3S2 by a hydrothermal method; 2) Ni3S2 was prepared using argon plasma bombardment to obtain S-vacancy-rich Ni3S 2-x ; 3) Ni3S 2-x Co@Ni3S 2-x was prepared by impregnation in an aqueous solution containing Co(N03)2-6H20 followed by calcination under H2 / Ar atmosphere.

3. Co@Ni3S of claim 2, wherein a single atom of Co is anchored at S vacancy 2-x Process for the preparation of a catalyst, characterized in that, In step 1), the amount of substance of thiourea is 0.2-0.6 mmol, the volume of deionized water is 25 mL, and the volume of foamed nickel is 3×2 cm.

4. Co@Ni3S of claim 2, wherein a single atom of Co is anchored at S vacancy 2-x Process for the preparation of a catalyst, characterized in that, In step 1), the ultrasonic oscillation method is used to uniformly disperse thiourea in deionized water, the ultrasonic power is 90 W, the ultrasonic time is 10-50 min, the hydrothermal temperature is 120-140 ℃, and the hydrothermal time is 12-20 h.

5. Co@Ni3S of claim 2, wherein a single atom of Co is anchored at S vacancy 2-x Process for the preparation of a catalyst, characterized in that, In step 2), the power of argon plasma bombardment is 80-120 W, and the bombardment time is 5-15 min.

6. A Co@Ni3S of single-atom Co anchored at S-vacancy as claimed in claim 2 2-x Process for the preparation of a catalyst, characterized in that, In step 3), the concentration of the Co(NO3)2·6H2O solution is 0.5-1.5 mmol / L, the impregnation time is 3 h, the calcination temperature is 300-400 ℃, the heating rate is 5 ℃ / min, and the calcination time is 1-3 h.

7. Co@Ni3S according to any one of claims 1 to 6 2-x Use of the catalyst in the electrocatalytic oxidation of PET.

Images