A copper atomic cluster modified carbon-based copper monatomic catalyst and a preparation method thereof

Abstract

This invention discloses a carbon-based copper single-atom catalyst modified with copper atom clusters and its preparation method. Cu-ACs / SAs uses 2-aminoterephthalic acid as a carbon-based precursor and is prepared by inducing Cu with ammonia water. 2+ It was prepared by self-assembly with 2-aminoterephthalic acid and combined with molten salt calcination. During the self-assembly process, ammonia water not only provided an alkaline environment to force the deprotonation of 2-aminoterephthalic acid, but also strengthened its reaction with Cu. 2+ The chemical coordination of the catalyst also promotes the formation of self-assembled compounds. Persulfate activation and pollutant degradation experiments show that Cu-ACs / SAs can efficiently activate persulfate and degrade organic pollutants under near-infrared light induction, exhibiting excellent stability and recyclability. The catalyst of this invention has a simple preparation process, significant catalytic effect, and high stability, demonstrating broad application potential.

Description

Technical Field

[0001] This invention belongs to the field of material preparation and advanced treatment of organic wastewater, specifically relating to a carbon-based copper single-atom catalyst modified with copper atom clusters and its preparation method. Background Technology

[0002] Environmental pollution has evolved into one of the major global challenges, with water pollution being particularly prominent. Large quantities of toxic and harmful pollutants, especially emerging organic pollutants, are constantly entering aquatic environments. Because they are difficult to decompose, they pose a serious threat to the ecological environment and human health.

[0003] In recent years, advanced oxidation technologies using persulfate as an oxidant (PS-AOPs) have been considered one of the most advanced wastewater treatment technologies for removing organic pollutants due to their ability to generate various oxygen-containing reactive species with high oxidation potentials within the system. To efficiently activate persulfate, researchers have explored and developed a large number of oxidants such as Co... 2+ Fe 2+ Ag + Homogeneous catalysts and heterogeneous catalysts such as Fe2O3 and Co3O4 are used. Although these catalysts all exhibit high persulfate activation performance, heterogeneous catalysts are favored by environmental workers due to their recyclability compared to homogeneous catalysts.

[0004] Unfortunately, most of the heterogeneous catalysts currently developed suffer from problems such as insufficient exposure of active sites, heterogeneous catalytic site structure, and easy filtration of metal ions. These factors significantly affect their efficiency in activating persulfate and degrading pollutants. Therefore, there is an urgent need to develop a highly efficient, stable catalyst with a uniform active site structure to activate persulfate in order to achieve PS-AOPs treatment of wastewater pollution.

[0005] Single-atom catalysts (SACs) have emerged as rising stars in the field of catalysis due to their high metal utilization, homogeneous and tunable composition and structure, and the combined characteristics of homogeneous and heterogeneous catalysts. Currently, single-atom catalysts centered on different metals are used for persulfate activation and pollutant degradation, demonstrating great potential. However, the single metal active center leads to excessive charge accumulation, resulting in insufficient performance of conventional single-atom catalysts in persulfate activation kinetics, leading to poor overall persulfate activation efficiency and low pollutant degradation performance. Therefore, to obtain a highly efficient single-atom activated PS-AOPs system for degrading organic pollutants, the development of novel single-atom-based catalysts is urgently needed. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing single-atom catalysts for activating persulfate to degrade pollutants, and to provide a carbon-based Cu single-atom catalyst modified with Cu atom clusters, its preparation method, and its application in efficiently activating persulfate to degrade organic pollutants.

[0007] The technical solution adopted in this invention is as follows: a carbon-based Cu single-atom catalyst modified with Cu atom clusters, the carbon-based Cu single-atom catalyst modified with Cu atom clusters is labeled as Cu-ACs / SAs, which is prepared by using 2-aminoterephthalic acid as a carbon-based precursor, inducing Cu components and 2-aminoterephthalic acid to achieve self-assembly through ammonia water, and combining it with molten salt calcination method.

[0008] Furthermore, a method for preparing a carbon-based copper single-atom catalyst modified with copper atom clusters includes the following steps:

[0009] Step S1: Prepare a self-assembled Cu component and 2-aminoterephthalic acid;

[0010] First, 2-aminoterephthalic acid was dispersed in 150 mL of ammonia solution and stirred for 15 min until completely dissolved. Then, 30 mL of CuSO4 aqueous solution was added dropwise under vigorous stirring and stirring was continued for 5 h. After centrifugation, washing with deionized water and vacuum drying at 60 °C, the resulting sample was denoted as Cu-NH2-BDC.

[0011] Step S2: Weigh the dried Cu-NH2-BDC sample and grind it evenly with a mixture of KCl and KBr salts. Then, put it into a crucible, compact it, and place it in a tube furnace. Calcinate it at high temperature under a nitrogen atmosphere so that Cu-NH2-BDC carbonizes and recombines under molten salt conditions to form a unified and ordered coordination structure and obtain a solid.

[0012] In step S3, the obtained solid is dispersed in deionized water to remove residual salts; finally, it is filtered and vacuum dried to obtain a solid, denoted as Cu-ACs / SAs.

[0013] Furthermore, in step S1, the concentration of ammonia water is 0.5-0.9% by volume fraction, the molar concentration of CuSO4 solution is 0.2-0.3 mol / L, and the molar ratio of CuSO4 to 2-aminoterephthalic acid is 1:1.5-1:2.5.

[0014] Furthermore, in step S2, the mass ratio of the mixed salt KCl to KBr is 1:2.5 to 1:3.5, the mass ratio of Cu-NH2-BDC to the mixed salt is 1:30 to 1:40, the calcination temperature is 720 to 750℃, and the calcination time is 2.5 to 3.5 h.

[0015] Furthermore, carbon-based Cu single-atom catalysts modified with Cu atom clusters were used to activate persulfate for the degradation of organic pollutants under near-infrared light induction.

[0016] The present invention uses 2-aminoterephthalic acid as a carbon-based support precursor, and induces Cu with ammonia water. 2+ A carbon-based Cu single-atom catalyst (Cu-ACs / SAs) modified with Cu atom clusters was prepared by self-assembling a precursor with 2-aminoterephthalic acid and then subjected to high-temperature heat treatment via molten salt method. During the self-assembly process, ammonia not only provided an alkaline environment to force the deprotonation of 2-aminoterephthalic acid, but also enhanced its affinity for Cu. 2+ The chemical coordination of ammonia also promotes the formation of self-assembled structures. Furthermore, ammonia itself can participate in Cu synthesis by donating lone pair electrons from its N atom. 2+ Coordination is achieved, thereby supplementing the nitrogen source. During calcination, the mixed salt melts into a liquid state at high temperature, effectively promoting the migration of metal components, accelerating metal dispersion and recombination, and achieving the synergistic coexistence of Cu single atoms and Cu atom clusters. Persulfate activation and pollutant degradation experiments show that Cu-ACs / SAs can efficiently activate persulfate and degrade organic pollutants under near-infrared light induction, exhibiting excellent stability and recyclability. The catalyst preparation process of this invention is simple, the catalytic effect is significant, and the catalytic system has high stability, showing broad application potential.

[0017] Furthermore, an application of a carbon-based Cu single-atom catalyst modified with Cu atom clusters: under near-infrared light induction, it can be used to activate persulfate and degrade organic pollutants.

[0018] The carbon-based Cu single-atom catalyst (Cu-ACs / SAs) modified with Cu atom clusters in this invention uses 2-aminoterephthalic acid as a carbon-based support precursor and ammonia water to induce Cu... 2+ The catalyst was prepared by self-assembly with 2-aminoterephthalic acid followed by high-temperature heat treatment under molten salt stress. This method is not only simple to operate, but the addition of ammonia water also facilitates the pre-establishment of the local coordination environment of the Cu component. Furthermore, the mixed salt heat treatment not only lowers the carbonization temperature but also enhances metal dispersion and improves surface porosity, which is beneficial for mass transfer during the reaction. In the synthesized material, the atomic clusters not only accelerate charge transport due to their lower Fermi levels but also inhibit the migration of individual metal atoms during the reaction, improving their stability and thus effectively enhancing the kinetics of persulfate activation and the efficiency of organic pollutant degradation. Currently, there are no reports on the preparation of atomic cluster-modified single-atom composite catalysts for the activation of persulfate degradation of organic pollutants using the method of this invention.

[0019] The significant advantages of this invention are:

[0020] (1) This invention is the first to utilize an ammonia-induced self-assembly synergistic molten salt high-temperature calcination strategy, using 2-aminoterephthalic acid as a carbon support precursor to coordinate Cu components, and preparing a carbon-based Cu single-atom catalyst modified with atomic clusters through high-temperature pyrolysis. This strategy can pre-set the local coordination environment of the metal center, reducing the uncertainty caused by migration in traditional pyrolysis. At the same time, it effectively reduces the pyrolysis temperature and promotes the dispersion of metal components, forming a dual effect of synergistic enhancement of spatial configuration and local structure, thereby improving the kinetics of persulfate activation and accelerating the removal efficiency of pollutants.

[0021] (2) The single-atom catalysts (Cu-ACs / SAs) modified by atomic clusters synthesized in this invention have porous surface morphology, which is conducive to the full exposure of metal active sites and mass transfer of catalytic substrate, thereby improving catalytic performance.

[0022] (3) The catalyst of the present invention has a simple preparation process, significant catalytic effect, high reproducibility and stable catalytic system, which is conducive to large-scale promotion and has broad application prospects. Attached Figure Description

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0024] Figure 1 These are the SEM images (a), TEM images (bc), spherical aberration electron microscopy STEM images (de), and elemental distribution maps (f) of Cu-ACs / SAs of the present invention.

[0025] Figure 2 This is the XRD pattern of Cu-ACs / SAs of the present invention.

[0026] Figure 3 This is a diagram showing the bisphenol A (BPA) degradation activity of the present invention, where (a) only PDS + near-infrared light is added, (b) only Cu-ACs / SAs are added under light-free conditions, and (c) nitrogen-doped porous carbon is added.

[0027] +PDS+near-infrared light, (d) is the addition of Cu-ACs / SAs and PDS under light-free conditions, (e) is the addition of Cu single-atom catalyst (Cu-SAs)+PDS+near-infrared light, and (f) is the addition of Cu-ACs / SAs+PDS+near-infrared light. Detailed Implementation

[0028] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0029] Comparative Example 1

[0030] The preparation of nitrogen-doped porous carbon (NC) catalyst involves the following steps: 400 mg of 2-aminoterephthalic acid and 14 g of a mixed salt of KCl and KBr (mass ratio 1:3) are uniformly mixed, packed into a crucible, compacted, and placed in a tube furnace for calcination at 730 °C for 3 h; after cooling to room temperature, the resulting solid is dispersed in 100 mL of deionized water, ultrasonically homogenized, and stirred for 2 h; after filtration, repeated washing, and drying, the solid is denoted as nitrogen-doped porous carbon (NC).

[0031] Comparative Example 2

[0032] The preparation of Cu single-atom (Cu-SAs) catalysts involved the following steps: 1.086 g of 2-aminoterephthalic acid was dispersed in 150 mL of 0.7% ammonia solution and stirred for 15 min until completely dissolved. Then, 30 mL of 0.25 mol / L CuSO4 aqueous solution was added dropwise under vigorous stirring, and stirring continued for 5 h. After centrifugation, washing with deionized water, and vacuum drying at 60 °C, the resulting sample was designated Cu-NH2-BDC. 400 mg of the dried Cu-NH2-BDC sample was weighed and mixed with 14 g of KCl and KBr (… The mixed salts (mass ratio 1:3) were uniformly mixed, packed into a crucible, compacted, and placed in a tube furnace. The mixture was calcined at 730°C for 3 hours under a nitrogen atmosphere to allow Cu-NH2-BDC to carbonize and recombine under molten salt conditions, forming a unified and ordered coordination structure. The resulting solid was then dispersed in 100 mL of deionized water, ultrasonically homogenized, and stirred for 2 hours to remove residual salts. Finally, it was etched in a 5 mol / L sulfuric acid solution and heated at 60°C for 24 hours to remove atomic clusters. After cooling, the solid was obtained by filtration, repeated washing, and drying, and is denoted as Cu single atoms (Cu-SAs).

[0033] Example 1

[0034] The preparation of Cu-ACs / SAs catalyst involved the following steps: First, 1.086 g of 2-aminoterephthalic acid was dispersed in 150 mL of 0.7% ammonia solution and stirred for 15 min until completely dissolved. Then, 30 mL of 0.25 mol / L CuSO4 aqueous solution was added dropwise under vigorous stirring, and stirring was continued for 5 h. After centrifugation, washing with deionized water, and vacuum drying at 60 °C, the resulting sample was designated Cu-NH2-BDC. 400 mg of the dried... The Cu-NH2-BDC sample was uniformly mixed with 14g of a mixed salt of KCl and KBr (mass ratio 1:3), packed into a crucible, compacted, and placed in a tube furnace. It was calcined at 730℃ for 3h under a nitrogen atmosphere to allow Cu-NH2-BDC to carbonize and recombine under molten salt conditions to form a unified and ordered coordination structure. The resulting solid was then dispersed in 100mL of deionized water, ultrasonically homogenized, and stirred for 2h to remove residual salts. Finally, solid Cu-ACs / SAs were obtained by filtration, repeated washing, and drying. Figure 1 SEM, TEM, aberration-corrected transmission electron microscopy (TEM) STEM, and elemental distribution maps of Cu-ACs / SAs are presented. The SEM and TEM images show that Cu-ACs / SAs exhibit a two-dimensional sheet-like structure. No Cu nanoparticles were observed, but numerous porous structures were found on the surface, which is beneficial for mass transfer of the reaction substrate. The STEM images show a large number of Cu single atoms anchored on the carbon material surface, along with numerous atomic-level clusters, indicating that the Cu-NH2-BDC precursor underwent carbonization reforming during calcination, with some Cu species agglomerating to form atomic-level clusters. The elemental distribution map shows that Cu is relatively uniformly distributed on the carbon support. XRD characterization shows that Cu-ACs / SAs have two broad diffraction peaks at approximately 2θ = 25.4° and 43.6°, which can be attributed to the (002) plane of graphitized carbon. No diffraction peaks of Cu nanoparticles were detected, consistent with the TEM results. Based on the above characterization, Cu-based single atoms and atomic clusters are indeed present in the catalyst, indicating that the carbon-based Cu single-atom catalyst modified with Cu atomic clusters was successfully synthesized.

[0035] Example 2

[0036] Bisphenol A (BPA) degradation performance: The synthesized catalyst was used to activate persulfate (PDS) for BPA degradation. The specific steps were as follows: 20 mg of the prepared Cu-ACs / SAs catalyst was weighed and dispersed in 50 mL of an aqueous solution containing 20 mg / L BPA. The mixture was stirred until homogeneous. 1.5 mmol / L PDS was added under near-infrared light excitation to trigger the reaction. Samples were taken periodically, filtered through a disposable filter, and the concentration of residual BPA was determined by high-performance liquid chromatography (HPLC). The degradation efficiency was as follows: Figure 3As shown, under near-infrared light irradiation, the concentration of BPA hardly changes when only PDS is added, indicating that PDS alone has no degradation activity for BPA. When only Cu-ACs / SAs are added, the removal rate of BPA is only 12.4%, and the removal efficiency does not change significantly with increasing reaction time, indicating that the Cu-ACs / SAs catalyst only has a simple adsorption effect on BPA. However, when PDS is added, the degradation effect of BPA is significantly improved, and it can be completely removed within 3 minutes, indicating that PDS can be effectively activated and remove BPA under the action of Cu-ACs / SAs catalyst. When porous carbon (C) is used to replace the Cu-ACs / SAs catalyst to activate PDS, the degradation efficiency of BPA is only 28.7%, indicating that the Cu component plays a key role in the activation of persulfate. Meanwhile, when Cu single atoms (Cu-SAs) are used to replace the Cu-ACs / SAs catalyst to activate PDS, the degradation efficiency of BPA reaches 71.7%. Although this efficiency indicates that the introduction of a single-atom metal improves catalyst performance, the catalyst's single metal active site leads to excessive charge accumulation, preventing complete BPA degradation. Furthermore, without the introduction of near-infrared light, Cu-ACs / SAs exhibited only a 67.1% BPA removal efficiency after 12 minutes in the presence of PDS, suggesting that near-infrared light plays a role in promoting catalytic efficiency. These experimental results demonstrate that Cu-ACs / SAs catalysts possess high PDS activation efficiency and pollutant degradation performance under near-infrared light induction.

[0037] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A carbon-based copper single-atom catalyst modified with copper atom clusters, characterized in that: The carbon-based Cu single-atom catalyst modified with Cu atom clusters, labeled Cu-ACs / SAs, is prepared using 2-aminoterephthalic acid as a carbon-based precursor. It achieves self-assembly of Cu components with 2-aminoterephthalic acid through ammonia-induced self-assembly, followed by molten salt calcination. During self-assembly, ammonia not only provides an alkaline environment that forces the deprotonation of 2-aminoterephthalic acid, but also enhances its affinity for Cu. 2+ The chemical coordination of ammonia also promotes the formation of self-assembled structures; furthermore, ammonia itself can participate in Cu by donating lone pairs of electrons through N atoms. 2+ Coordination, thereby replenishing the nitrogen source; A method for preparing a carbon-based copper single-atom catalyst modified with copper atom clusters includes the following steps: Step S1: Prepare a self-assembled Cu component and 2-aminoterephthalic acid; First, 2-aminoterephthalic acid was dispersed in 150 mL of ammonia solution and stirred for 15 min until completely dissolved. Then, 30 mL of CuSO4 aqueous solution was added dropwise under vigorous stirring and stirring was continued for 5 h. After centrifugation, washing with deionized water and vacuum drying at 60 °C, the resulting sample was denoted as Cu-NH2-BDC. Step S2: Weigh the dried Cu-NH2-BDC sample and grind it evenly with a mixture of KCl and KBr salts. Then, put it into a crucible, compact it, and place it in a tube furnace. Calcinate it at high temperature under a nitrogen atmosphere so that Cu-NH2-BDC carbonizes and recombines under molten salt conditions to form a unified and ordered coordination structure and obtain a solid. Step S3: The obtained solid is dispersed in deionized water to remove residual salts; finally, it is filtered and vacuum dried to obtain a solid, denoted as Cu-ACs / SAs. In step S1, the concentration of ammonia water is 0.5-0.9% by volume fraction, the molar concentration of CuSO4 solution is 0.2-0.3 mol / L, and the molar ratio of CuSO4 to 2-aminoterephthalic acid is 1:1.5-1:2.

5. In step S2, the mass ratio of the mixed salt KCl to KBr is 1:2.5 to 1:3.5, the mass ratio of Cu-NH2-BDC to the mixed salt is 1:30 to 1:40, the calcination temperature is 720 to 750℃, and the calcination time is 2.5 to 3.5 h.

2. The application of the carbon-based copper single-atom catalyst modified with copper atom clusters as described in claim 1, characterized in that: Carbon-based Cu single-atom catalysts modified with Cu atom clusters were activated under near-infrared light to degrade organic pollutants using persulfate.

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