Tóm tắt Luận án Synthesis and characterizations of copper nanoparticles material

MINISTRY OF EDUCATION AND TRAINING VIETNAM ACADEMY SCIENCE AND TECHNOLOGY GRADUATE UNIVERSITY OF SCIENCE AND TECHNOLOGY CAO VAN DU SYNTHESIS AND CHARACTERIZATIONS OF COPPER NANOPARTICLES MATERIAL Specialization: inorganic chemistry Code number: 62 44 01 13 DOCTORAL THESIS ABSTRACTS’ INORGANIC CHEMISTRY Ho Chi Minh City – 2016 The work was completed at: Laboratory nano Lac Hong University, Laboratory of nano University of Natural Sciences, Institute for Materials Science Applications, Vietnam Academy of Science and Technology Scientific guidance: 1. Assoc. Prof. Dr. Nguyen Thi Phuong Phong 2. Dr. Nguyen Thi Kim Phuong 1st Peer Reviewer: 2nd Peer Reviewer: 3rd Peer Reviewer: The theeesis dissertation will be defended in front of doctoral thesis judgement, held at the Academy of Sciences Institute of Applied Materials, Graduate University of Science and Technology , No. 1 , Mac Dinh Chi , District 1, HCMC city, Viet Nam. At ......, , 2016 Can learn dissertation at the library: National Library of Vietnam, Library of Vietnam Academy of Science and Technology 1 INTRODUCTION In recent years, metal nanoparticles have attracted the attention of scientists due to their special properties that differ distinctly from the corresponding bulk materials by surface area to volume ratio and small size of them. The ability to synthesize metal nanoparticles with different shapes and sizes is important to explore their applications in electronics, catalysis, sensors, optical and biological devices. As most of these applications were governed by silver, gold and platinum. However, the high cost constraint of these metals restricted their applications in high volume production. Presently, copper nanoparticles provided a good alternative of silver, gold and platinum nanoparticles because of their lower cost and catalytic activity, novel electronic, optical and magnetic properties or have antibacterial and antifungal properties ... Compared to other metal nanoparticles materials, the synthesis of copper nanoparticles are more difficult because of surface easy oxidizing of copper. Therefore, the synthesis of copper nanoparticles with high purity would be a prerequisite for many application areas such as electricity - electronics, optics, catalysis, chemistry, biology ... Up to now, several methods have been developed for the preparation of copper nanoparticles, such as electron irradiation, the plasma process, chemical reduction method, in situ methods, two-step reduction method, thermal decomposition, electro-chemical reduction, reduction with ultrasound, microwave heating, supercritical methods, ... Methods for the preparation of copper nanoparticles often common aim is to create nanoparticles at small sizes, high-stability for maximize applications. However, a large number of published on synthetic of copper nanoparticles still has many disadvantages, such as long time or high temperatures to complete the reaction, copper salts were chemically reduced in organic solvents under strict conditions, complex equipment systems, using capping agents not guarantee for the stability of the copper nanoparticles colloidal solutions. Moreover, in the most recent published works, one of the most important applications of the copper nanoparticles was tested for antibacterial to treat and kill drug-resistant microorganisms. The results showed that copper nanoparticles colloidal solutions shown bactericidal activity with various gram (-), gram (+) cause disease in humans and animals. Antifungal activity has not been mentioned much, only published work of Sahar M. Ouda (2014) showed results in resistance against two strains of plant pathogenic fungi on Botrytis cinerea is Alternaria alternate and Botrytis cinerea. On this basis, to overcome the disadvantages of synthetic copper nanoparticles with traditional chemical reaction system. The content of the thesis is performed primarily with the synthesis of copper nanoparticles from the basic reaction systems including precursor, protection and reducing agent. The limitations of these reaction system will be improved by the synthesis of the new systems that is a combination of two or three protections. The combination of protective substances include protection of large molecular weight (PVA) and the protection of small molecular weight (trisodium citrate, ascorbic acid, CTAB) will make new rules of the synergistic effect in order to control the size and ensure the 2 stability of copper nanoparticles. The thesis also clarified the physicochemical and biological characteristics of copper nanoparticles materials forming. The main contents of the thesis: - Synthesis of the copper nanoparticles colloidal solutions by chemical reduction method with various precursors including copper oxalate, CuCl2, CuSO4, Cu(NO3)2 with hydrazine hydrate reducing agent, NaBH4; solvent glycerin and water, PVA and PVP protection, dispersants and protective agents: including trisodium citrate, ascorbic acid, CTAB. - Investigating the influence of the parameters in the synthesis to the shape, size and distribution of copper nanoparticles forming such as reaction temperature, concentration of reducing agent, the ratio of precursors and capping agent, solution pH. - Investigating the effect of the protective agent PVA, PVP, dispersants trisodium citrate, ascorbic acid protect auxiliaries, CTAB surfactant to the size and distribution of copper nanoparticles forming. - Investigating the specific physicochemical properties of copper nanoparticles forming by the modern analytical methods such as UV-Vis spectrum, X-ray diffraction (XRD), transmission electron microscopy (TEM). - Investigating the antifungal activity and high killing ability against Corticium salmonicolor of the copper nanoparticles colloidal solutions in the laboratory. Meaning of science and practice of the thesis The thesis provides the basis for the study a systematic process of synthetic copper nanoparticles material overview domestic and foreign researches. The results of the thesis will make clarify the rules of relationship between the size of copper nanoparticles forming with their special characteristic is surface plasmon resonance via UV-Vis spectrum. By using a various of precursors, reducing agents, protective agents, the synthesis was performed with the survey parameters which control the size of copper nanoparticles forming, from that explore best bioavailability of the copper nanoparticles colloidal solutions. This is also the scientific basis for subsequent applied research. The layout of the thesis: The thesis has 128 pages with 8 tables, 108 figures. Besides the introduction (3 pages), conclusions (2 pages), list of publications (2 pages) and references is updated to 2015 (9 pages), Annex (11 pages). The thesis is divided into 3 chapters as follows: Chapter 1 : Overview 28 pages Chapter 2 : Experimental 10 pages Chapter 3 : Results and discussions 74 Pages New contributions of the thesis 1. The first time thesis presented a systematic synthesis of the copper nanoparticles colloidal solutions base on chemical process with various precursors including copper oxalate, CuCl2, CuSO4, 3 Cu(NO3)2, various reducing agents: hydrazine hydrate, NaBH4; protective agents: PVA and PVP, dispersant and protective agents: trisodium citrate, ascorbic acid, CTAB in 2 solvent: glycerin and water. The novelty of the thesis was use glycerin solvent and protective agents (PVP, PVA, trisodium citrate) to ensure the formation of colloidal solutions with high stability. 2. Rules, relationships between the size of copper nanoparticles with absorption peak shift through surface plasmon resonance from UV-Vis analysis were characterised and clarified. Characterization: Using the chemical reduction method with reducing agent hydrazine hydrate, NaBH4 to synthesize the copper nanoparticles colloidal solutions from precursors (copper nitrate, copper chloride, copper sulfate). Using thermal reducing method with the used glycerol both solvent and reduction to synthesis the copper nanoparticles colloidal solutions from copper oxalate precursors. Using thermal analysis DTA-TG to determine temperature ranges that CuC2O4 changes volume, creating the basis for the synthesis of copper nanoparticles from copper oxalate precursors. Using UV-Vis to determine the optical properties, the shift plasmon absorption peaks of copper nanoparticles. Predicting the size of copper nanoparticle forming. Using X-ray diffraction (XRD) to determine the crystal structure, the purity of the copper nanoparticles. Using TEM to determine the morphology, size, combined with IT3 software to perform particle size distribution of copper nanoparticles. Using invitro testing method and spray directly method for testing antifungal activity and high killing ability against C. salmonicolor. 3. RESULTS AND DISCUSSION 3.1 Synthesis of copper nanoparticles from copper oxalate precursors 3.1.2 Investigating the influence of the parameters on the size of copper nanoparticles 3.1.2.1 Effect of temperature Figure 3.5 is the result UV-Vis spectrum of the copper nanoparticles colloidal solutions, the results showed: - Curve (a): UV-Vis spectrum of the mixture CuC2O4 dispersed in glycerin, only show an absorbance peak at 305 nm wavelength; this is the absorbance peak of the copper oxalate. - Curve (b): UV-Vis spectrum of the samples was prepared at reaction temperature of 220 o C, reaction time was 2 minutes. The results show that besides the absorbance peak at 305 nm wavelength, There is an absorbance peak appears at wavelength 580 nm. This is the absorbance peak of copper nanoparticles, this phenomenon was result of the surface plasmon resonance that occurs with copper nanoparticles. This result indicates that the reaction had occurred to form copper nanoparticles, but the reaction did not occur completely, therefor still has copper oxalate in solution. This result compare with the result of the thermal analysis DTA - TG Figure 3.4 could conclude that the reaction did not occur by the thermal decomposition mechanism, because the reaction of thermal decomposition copper oxalate 4 only occurs at temperatures of 270 °C. Thus, with the result obtained, it can be concluded that the reaction formed copper nanopaticles occurs in both thermal reduction and chemical reduction mechanism with glycerin acts as both solvent and reduction. - Curve (c): Samples were prepared at temperature of 230 o C, UV-Vis results showed that there was only the absorbance peak at 584 nm wavelength; do not appears absorbance peak of copper oxalate. Thus, the reduction of copper oxalate has occurred almost completely. Copper nanoparticles were synthesized at 240 °C with unchanged reaction conditions. Figure 3.6 and 3.7 are TEM images and particle size distributions of copper nanoparticles were synthesized at temperature of 230 °C and 240 °C. At temperatures of 230 °C, the copper nanoparticles were created in spherical, had average diameter in range of 12 ± 3.6 nm (Figure 3.6). At temperature of 240 °C, copper nanoparticles have spherical with the average size in range of 29.6 ± 4.2 nm (Figure 3.7). 3.1.2.2 Effect of ratio CuC2O4/PVP Table 3.1: Data and results of the copper nanoparticles were synthesized via ratio CuC2O4/PVP Samples ratio (%) CuC2O4/PVP PVP (g) CuC2O4 (g) Temperature ( o C) Absorbance peak (nm) Average size via TEM (nm) K1 1 0.2 0.002 230 580 5.5 ± 2.3 K2 3 0.006 585 K3 5 0.010 592 36 ± 5 K4 7 0.014 598 K5 9 0.018 600 68 ± 6.3 K6 11 0.022 614 K7 15 0.030 623 Table 3.1 shows summarily UV-Vis and TEM results of the copper nanoparticles colloidal solutions. The results showed that all samples had phenomenon of surface plasmon resonance which occurs with copper nanoparticles at the position of maximum absorbance peaks were K1 (580 nm), K2 Figure 3.6: TEM and particle size distribution of CuPNs were synthesized at 230 o C) Figure 3.6: TEM and particle size distribution of CuPNs were synthesized at 240 o C) Figure 3.5: UV-Vis spectra of (a) copper oxalate, (b) CuNPs + copper oxalate (220 °C, (c) and CuNPs (230 oC) 5 (585 nm ), K3 (592 nm), K4 (598 nm), K5 (600 nm), K6 (614nm), K7 (623 nm) corresponding to ratio CuC2O4 / PVP is 1, 3, 5, 7, 9, 11 , 15%, respectively. The absorbance peaks of the copper nanoparticles colloidal solutions shift to larger wavelengths (redshift) from 580 to 623 nm, while the intensity of the absorance peaks also increased. According to Mie theory, it could be predicted that the size of copper nanoparticles increase when the ratio CuC2O4/PVP increases from 1 to 15 %. The results of TEM images in Figure 3.11 to Figure 3.13 show that, at concentration 1 % of CuC2O4 compared to PVP, copper nanoparticles were created mostly in spherical and distributed with the average size was 5.5 ± 2.3 nm (Figure 3.11). When concentration of CuC2O4 increase to 5 % (Figure 3.12) and 9 % (Figure 3.13) compared to PVP, copper nanoparticles forming were distributed in a wide range and agglomerated, with the average size 36 ± 5 nm and 68 ± 6.3 nm, respectively. These results were consistent entirely compared to the shift position of maximum absorance peaks of copper nanoparticles in the UV-Vis spectrum from 580 to 600 nm. 3.1.2.3 Effect of pH Initial solution has neutral pH values, to investigate the influence of solution pH to the formation of copper nanoparticles colloidal solutions, the reaction solution was controlled pH by NaOH 0.1 M. All samples were prepared with the same condition such as CuC2O4/PVP = 5 %, the reaction time was 2 minutes. Preliminary experiments showed that when the solution pH of the mixture increases, the reaction to form copper nanoparticles occurs at lower temperatures (140 °C). Observe the change of color in the solution pH adjustment process as well as the actual reaction occured, the synthesis mechanism was changed and can be explained as follows: when adding NaOH to the mixture along with mixing, the mixture of copper oxalate in glycerol changed the color from light blue to dark blue, this could be the formation of complex [Cu(OH)4] 2+ , this complex could be bonded with PVP at the position of nitrogen and oxygen in a chain of molecule PVP. Thus, potential redox (ECu 2+ /Cu) changed and made the ΔG value of reaction was more negative, therefor the temperature of the reaction in the case of high solution pH ( 8) will be lower (140 °C) compared to the reaction occurs at neutral solution pH (230 o C). Figure 3.11: TEM image and particle size distribution of CuNPs were synthesized in the weight ratio CuC2O4 /PVP = 1 % Figure 3.12: TEM image and particle size distribution of CuNPs were synthesized in the weight ratio CuC2O4 /PVP = 5 % Figure 3.13: TEM image and particle size distribution of CuNPs were synthesized in the weight ratio CuC2O4 /PVP = 9 % 6 Table 3.2: Data and results of the copper nanoparticles were synthesized via solution pH Samples pH Value Ratio (%) CuC2O4/PVP Temperature ( o C ) Absorbance peak (nm) Average size via TEM (nm) Particle shape K3 7 5 230 592 36 ± 5 spherical D1 8 140 596 D2 9 600 77 ± 5.3 spherical, polygon D3 10 601 82 ± 4.2 spherical, polygon D4 11 601 D5 12 600 96 ± 5.6 spherical, cubic, triangle, rod The results were summarized in Table 3.2 shows that, when the pH value increases in 8 ÷ 12, the copper nanoparticles had phenomenon of surface plasmon resonance corresponding to maximum absorbance peaks at wavelengths 596; 600; 601; 601; 600 nm, respectively. TEM images showed that, when the solution pH increases, the size of copper nanoparticles forming also increases. Specific, the average size of the copper nanoparticles at pH = 9, pH = 10, pH = 12 in range of 77 ± 5.3 nm (Figure 3.16), 82 nm ± 4.2 (Figure 3.17), 96 ± 5.6 nm (Figure 3.18), respectively. In particular, copper nanoparticles were formed not only spherical but also cubic, triangle, rod, polygon. 3.2 Synthesis of copper nanoparticles from copper salt precursors 3.2.1 Synthesis of copper nanoparticles from copper nitrate precursors 3.2.1.1 Effect of the concentration of reducing agent Figure 3.22 to Figure 3.24 were TEM images and the particles size distribution of copper nanoparticles were synthesized at different concentrations of reducing agent. Figure 3.22 shows that, at HH concentration 0.1 M, the copper nanoparticles forming had smallest average size (14 ± 9 nm). However, the particle size distribution was created in the wide range from 6 ÷ 47 nm, mostly in spherical and combined of smaller particle size. When increases HH concentrations from 0.2 to 0.5 M, the copper nanoparticles were created in spherical and monodisperse with average size 25 ± 5 nm (Figure 3.23) and 67 ± 9 nm (Figure 3.24) respectively. Figure 3.17: TEM image and particle size distribution of CuNPs were synthesized at solution pH = 10 Figure 3.18: TEM image and particle size distribution of CuNPs were synthesized at solution pH = 12 Figure 3.16: TEM image and particle size distribution of CuNPs were synthesized at solution pH = 9 7 3.2.1.2 Effect of temperature Figure 3.27 to 3.29 were TEM images and particle size distribution of the copper nanoparticles were synthesized at different temperatures. At temperatures of 110 °C (Figure 3.27), the copper nanoparticles were created in spherical, monodisperse with average size of 17 ± 4 nm. As the temperatures were higher, at 130 °C (Figure 3.28) and 150 °C (Figure 3.29) the copper nanoparticles forming had larger size, in a wide range with the average size 33 ± 5 nm and 50 ± 20 nm respectively. 3.2.1.3 Effect of ratio Cu(NO3)2/PVP Figure 3.33: TEM image and particle size distribution of CuNPs were synthesized with ratio of Cu(NO3)2/PVP = 3 % Figure 3.27: TEM image and particle size distribution of CuNPs were synthesized at 110 o C Figure 3.29: TEM image and particle size distribution of CuNPs were synthesized at 150 o C Figure 3.28: TEM image and particle size distribution of CuNPs were synthesized at 130 o C Figure 3.22: TEM image and particle size distribution of CuNPs were synthesized at HH concentration 0.1 M Figure 3.23: TEM image and particle size distribution of CuNPs were synthesized at HH concentration 0.2 M Figure 3.24: TEM image and particle size distribution of CuNPs were synthesized at HH concentration 0.5 M Figure 3.32: TEM image and particle size distribution of CuNPs were synthesized with ratio of Cu(NO3)2/PVP = 1 % Figure 3.33: TEM image and particle size distribution of CuNPs were synthesized with ratio of Cu(NO3)2/PVP = 7 % 8 The results of TEM images from Figure 3:32 to 3:34 shows, as ratio of Cu(NO3)2/PVP was 1 %, the copper nanoparticles were formed mainly in spherical, monodisperse in range of 5 ± 3 nm (Figure 3.32). When the ratio of Cu(NO3)2/PVP increased to 3% and 7%, the copper nanoparticles were formed still in spherical and had diameter with average size of 15 ± 5 nm (Figure 3:33) and 22 ± 5 nm (Figure 3:34) respectively, the copper nanoparticles were agglomerated.  Summary and general discussion about the results of copper nanoparticles were synthesized from copper oxalate and copper nitrate precursors when using only PVP as protective agent: Table 3.4: Summary the results of copper nanoparticles were synthesized from copper oxalate and copper nitrate precursors Precursors/ synthetic co