稳定型氧化铜粉体表面活性剂的合成与表征

B. Bita, V. Ţucureanu, I. Cernica, M. Popescu, A. Matei, C. Romanițan
{"title":"稳定型氧化铜粉体表面活性剂的合成与表征","authors":"B. Bita, V. Ţucureanu, I. Cernica, M. Popescu, A. Matei, C. Romanițan","doi":"10.21741/9781945291999-6","DOIUrl":null,"url":null,"abstract":"In the present work, CuO nanoparticles were successfully prepared by the coprecipitation method using copper acetate (Cu(CH3COO)2) as a basic precursor, sodium hydroxide (NaOH) as a precipitator material, sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) as anionic and cationic surfactants, respectively. The synthesized powders samples were characterized by Fourier transform infrared spectrometry (FTIR), field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The investigation showed that the added types of surfactants have effects on the decrease of the crystallite size, on the CuO particles morphology, shape and uniform distribution as it is noticed in the XRD and SEM characterizations. Additionally, the FTIR spectra for all the powders samples showed the same Cu-O stretching vibration mode which indicates the presence of a crystalline CuO monoclinic structure. The obtained results create premises for further advanced the applications of CuO powders in various domains. Introduction Over the years, the interests in developing nanoparticles metal oxides have considerably increased due to the necessity of obtaining materials with outstanding physical and chemical properties. Various methods of metal oxide synthesis have been know so far, researches continue to development a new approaches with a strict control over nanoparticles morphology, size and composition for several technological applications. Copper oxide (CuO), belonging to the nanomaterials class, which has attracted recent research because of its excellent properties, cost effectiveness and wide spectrum of practical applications (solar and electrochemical cells, gas sensors, field emitters, active catalyst and antimicrobial activity, etc.). Also, CuO as nanostructured oxide being classified as a p-type monoclinically structured semiconductor material with a direct band-gap value of 1.85 eV presents a particular attention. This type of material has a special concern because it extends the use in a board range of applications, such as electronics and optoelectronics, catalysts, sensors and biosensors, chemical sensing devices, nanofluids and field emitters, desinfection, cosmetic pigments, antibacterial agent, etc. [1–4]. In order for this material to exhibit viable properties in the desired field of applicability, it is intended to establish its method of obtaining and its synthesis parameters; there Powder Metallurgy and Advanced Materials – RoPM&AM 2017 Materials Research Forum LLC Materials Research Proceedings 8 (2018) 52-60 doi: http://dx.doi.org/10.21741/9781945291999-6 53 have been elaborated and known various physical and chemical methods so far, such as sol-gel, coprecipitation, hydrothermal synthesis, mechanical mixing, solid state reaction, thermal descomposition of precursors, microemulsion, microwave irraditiaon, physical vapor deposition, ablation, etc. [3, 5, 6]. From the bottom-up type methods, precipitation is a cheap one, with applicability on a broadscale, and which does not involve the addition of secondary reaction products [7–9]. Particularly, in order to obtain CuO, the method involves precipitation of various soluble copper salts (nitrates, chlorides, sulphates and acetates) in aqueous solutions, followed by their thermal decomposition with oxide formation [4, 5, 10]. Inorganic salts are mixed in an aqueous medium and under a rigorous pH control by using solutions of NaOH, KOH, (NH4)2CO3 or NH4OH, finally the precipitates obtained are subject to characteristic thermal treatment. In the synthesis process the reaction parameters (pH, rate of addition of reactants and speed of stirring, solution concentration, reaction temperature, etc.) have a determining role in the particle size, morphology and granulometry [11 – 13]. In the literature various thermal treatments at relatively high temperature (between 700 °C and 1100 °C) are presented, leading to the phenomenon of agglomeration and increase of particles average size. To prevent the tendency of agglomeration and to favour the formation of nanostructured materials, the use surfactants have been proposed to be used. The use of different surfactants allows the improvement of particles structural, physico-chemical and morphological properties due to the electrostatic and stearic stabilizing mechanisms that reduce the solutions surface tension and improve the nanocrystalline material properties [6, 14 – 18]. Also, the addition of surfactants in the oxide materials precipitation process leads to increase nanoparticle stability and interaction between surfactant molecules and metal ions. The surfactants are chemical substances, focusing on the surface and solubilized materials with low affinity relative to each other. They have an asymmetrical molecular structure, consisting of a non-polar (hydrocarbon) and a polar (ionisable or non-ionisable) part. The role of surfactants is to provide an effective and efficient coating to induce electrostatic or stearic repulsions that can counterbalance van der Waals attractions [19 – 22]. The specialized literature shows research studies to improve the properties and formation of CuO nanoparticles by using various surfactants of the type of of oleic acid (OA), polyethylene glycol (PEG), cetyltrimethylammonium bromide (CTAB), hypochlorite dodecyl sulphate (SDS), polyvinylpyrrolidone (PVP), tetraoctylammonium bromide (TOAB), playing an important role in the synthesis process steps since the incipient phase. The reason for selecting the two types of surfactants (CTAB and SDS) in the experiments carried out in the present study is based on their remarkable effects on particle stability, size changing, morphology and the surface properties of the precipitated particles, but also because they have low price, can be found relatively easy on the market and have low toxicity [7, 14, 23 – 25]. This paper presents the study of obtaining CuO nanoparticles by the coprecipitation method, in the absence and in the presence of two types of surfactants, anionic (SDS) and cationic (CTAB). It is presented the effect of surfactants on CuO nanoparticles morphology, average size and crystalline structure. The morphological and structural properties are highlighted by using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Fourier transform infrared spectrometry (FT-IR). Powder Metallurgy and Advanced Materials – RoPM&AM 2017 Materials Research Forum LLC Materials Research Proceedings 8 (2018) 52-60 doi: http://dx.doi.org/10.21741/9781945291999-6 54 Experimental details For the synthesis of CuO powders: copper acetate monohydrate [Cu(CH3COO)2], sodium hydroxide [NaOH] and surfactants of type anionic [C12H25NaO4S, SDS 99%] and [C19H42BrN, CTAB > 99 %], were used as starting materials. All reagents were purchased from the company Sigma-Aldrich without any previous purification. For the synthesis of CuO in the absence and in the presence of surfactants the stock solutions of 1M [Cu(CH3COO)2] and 1M [NaOH] were prepared, respectively. From the stock solution of acetate one part is taken and the pH is adjusted in basic medium by adding NaOH solution in dropwise until the formation of a greenish-blue precipitate was observed. In the case of samples with surfactant, over the source of copper the afferent surfactants (SDS and CTAB concentration 0.1 M) was added and under continuous stirring the precipitating agent (NaOH) was adding in dropwise until the precipitate formed and the pH was adjusted to about 1011. After the precipitation formation, the stirring continues up to a temperature of 80 °C. The introduction of SDS anionic surfactant induces a homogeneous nuclear process due to considerable size effect of counter-ions on the crystal facets. By adding CTAB as a cationic surfactant there is a complete ionization and cation formation in the tetrahedric structure, but it also determines a control of the growth rates of different faces of the CuO nanoparticles [14, 26]. For all synthesized samples the same synthetic conditions (time, temperature and pH) were maintained. The precipitates thus formed are left in the rest position, then have been filtered under vacuum using a Buchner funnel, and following they were washed with a water-ethanol mixture for purification and removal of the secondary compounds. After washing, the samples were subjected to the drying step in the oven at a temperature of 80 °C, preceded by calcination sintering at a temperature of 550 °C for 3 hours in normal atmosphere. Due to the sintering temperature of the dry samples changed colour from green to blue to black. The functional groups and the chemical bonds of the synthesized oxide samples were analyzed by Fourier Transform Infrared spectrometry (Bruker Optics, Vertex 80V) using the KBr pellet method in the wavenumber range of 4000-400 cm by averaging 64 scans. In the processing of all spectra, the bands attributable to the vibration mode of the C=O bond in CO2 were extracted. In order to investigate the morphology and particle size a Field Emission Scanning electron microscope (FE-SEM), obtained at an operating voltage at 10 kV and a magnitude of 30 000x has been used. X-ray diffraction measurements of the synthesized CuO particles were recorded using a Rigaku Smartlab diffractometer with the radiation CuKa=1.540593 Å, indicating the limit of variation for the current between 150 mA and 190 mA. Data were collected at a scan rate of 12°/min. in the range 20 = 20-95°. Results and Discussion FTIR Spectra The FTIR spectra of the different samples are presented as a comparison between CuO powders obtained in the absence of surfactants (Figure 1a) and in the presence of surfactants (Fig. 1b and c). For all samples treated at 550 °C, bands attributed to both the vibration mode of the Cu-O linkages in the precursor and to the surfactants vibration mode can be seen, thus suggesting the binding of surfactants to particle surface. Band","PeriodicalId":20390,"journal":{"name":"Powder Metallurgy and Advanced Materials","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2018-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":"{\"title\":\"Synthesis and characterization of various surfactants for stabilized CuO powder\",\"authors\":\"B. Bita, V. Ţucureanu, I. Cernica, M. Popescu, A. Matei, C. Romanițan\",\"doi\":\"10.21741/9781945291999-6\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"In the present work, CuO nanoparticles were successfully prepared by the coprecipitation method using copper acetate (Cu(CH3COO)2) as a basic precursor, sodium hydroxide (NaOH) as a precipitator material, sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) as anionic and cationic surfactants, respectively. The synthesized powders samples were characterized by Fourier transform infrared spectrometry (FTIR), field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The investigation showed that the added types of surfactants have effects on the decrease of the crystallite size, on the CuO particles morphology, shape and uniform distribution as it is noticed in the XRD and SEM characterizations. Additionally, the FTIR spectra for all the powders samples showed the same Cu-O stretching vibration mode which indicates the presence of a crystalline CuO monoclinic structure. The obtained results create premises for further advanced the applications of CuO powders in various domains. Introduction Over the years, the interests in developing nanoparticles metal oxides have considerably increased due to the necessity of obtaining materials with outstanding physical and chemical properties. Various methods of metal oxide synthesis have been know so far, researches continue to development a new approaches with a strict control over nanoparticles morphology, size and composition for several technological applications. Copper oxide (CuO), belonging to the nanomaterials class, which has attracted recent research because of its excellent properties, cost effectiveness and wide spectrum of practical applications (solar and electrochemical cells, gas sensors, field emitters, active catalyst and antimicrobial activity, etc.). Also, CuO as nanostructured oxide being classified as a p-type monoclinically structured semiconductor material with a direct band-gap value of 1.85 eV presents a particular attention. This type of material has a special concern because it extends the use in a board range of applications, such as electronics and optoelectronics, catalysts, sensors and biosensors, chemical sensing devices, nanofluids and field emitters, desinfection, cosmetic pigments, antibacterial agent, etc. [1–4]. In order for this material to exhibit viable properties in the desired field of applicability, it is intended to establish its method of obtaining and its synthesis parameters; there Powder Metallurgy and Advanced Materials – RoPM&AM 2017 Materials Research Forum LLC Materials Research Proceedings 8 (2018) 52-60 doi: http://dx.doi.org/10.21741/9781945291999-6 53 have been elaborated and known various physical and chemical methods so far, such as sol-gel, coprecipitation, hydrothermal synthesis, mechanical mixing, solid state reaction, thermal descomposition of precursors, microemulsion, microwave irraditiaon, physical vapor deposition, ablation, etc. [3, 5, 6]. From the bottom-up type methods, precipitation is a cheap one, with applicability on a broadscale, and which does not involve the addition of secondary reaction products [7–9]. Particularly, in order to obtain CuO, the method involves precipitation of various soluble copper salts (nitrates, chlorides, sulphates and acetates) in aqueous solutions, followed by their thermal decomposition with oxide formation [4, 5, 10]. Inorganic salts are mixed in an aqueous medium and under a rigorous pH control by using solutions of NaOH, KOH, (NH4)2CO3 or NH4OH, finally the precipitates obtained are subject to characteristic thermal treatment. In the synthesis process the reaction parameters (pH, rate of addition of reactants and speed of stirring, solution concentration, reaction temperature, etc.) have a determining role in the particle size, morphology and granulometry [11 – 13]. In the literature various thermal treatments at relatively high temperature (between 700 °C and 1100 °C) are presented, leading to the phenomenon of agglomeration and increase of particles average size. To prevent the tendency of agglomeration and to favour the formation of nanostructured materials, the use surfactants have been proposed to be used. The use of different surfactants allows the improvement of particles structural, physico-chemical and morphological properties due to the electrostatic and stearic stabilizing mechanisms that reduce the solutions surface tension and improve the nanocrystalline material properties [6, 14 – 18]. Also, the addition of surfactants in the oxide materials precipitation process leads to increase nanoparticle stability and interaction between surfactant molecules and metal ions. The surfactants are chemical substances, focusing on the surface and solubilized materials with low affinity relative to each other. They have an asymmetrical molecular structure, consisting of a non-polar (hydrocarbon) and a polar (ionisable or non-ionisable) part. The role of surfactants is to provide an effective and efficient coating to induce electrostatic or stearic repulsions that can counterbalance van der Waals attractions [19 – 22]. The specialized literature shows research studies to improve the properties and formation of CuO nanoparticles by using various surfactants of the type of of oleic acid (OA), polyethylene glycol (PEG), cetyltrimethylammonium bromide (CTAB), hypochlorite dodecyl sulphate (SDS), polyvinylpyrrolidone (PVP), tetraoctylammonium bromide (TOAB), playing an important role in the synthesis process steps since the incipient phase. The reason for selecting the two types of surfactants (CTAB and SDS) in the experiments carried out in the present study is based on their remarkable effects on particle stability, size changing, morphology and the surface properties of the precipitated particles, but also because they have low price, can be found relatively easy on the market and have low toxicity [7, 14, 23 – 25]. This paper presents the study of obtaining CuO nanoparticles by the coprecipitation method, in the absence and in the presence of two types of surfactants, anionic (SDS) and cationic (CTAB). It is presented the effect of surfactants on CuO nanoparticles morphology, average size and crystalline structure. The morphological and structural properties are highlighted by using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Fourier transform infrared spectrometry (FT-IR). Powder Metallurgy and Advanced Materials – RoPM&AM 2017 Materials Research Forum LLC Materials Research Proceedings 8 (2018) 52-60 doi: http://dx.doi.org/10.21741/9781945291999-6 54 Experimental details For the synthesis of CuO powders: copper acetate monohydrate [Cu(CH3COO)2], sodium hydroxide [NaOH] and surfactants of type anionic [C12H25NaO4S, SDS 99%] and [C19H42BrN, CTAB > 99 %], were used as starting materials. All reagents were purchased from the company Sigma-Aldrich without any previous purification. For the synthesis of CuO in the absence and in the presence of surfactants the stock solutions of 1M [Cu(CH3COO)2] and 1M [NaOH] were prepared, respectively. From the stock solution of acetate one part is taken and the pH is adjusted in basic medium by adding NaOH solution in dropwise until the formation of a greenish-blue precipitate was observed. In the case of samples with surfactant, over the source of copper the afferent surfactants (SDS and CTAB concentration 0.1 M) was added and under continuous stirring the precipitating agent (NaOH) was adding in dropwise until the precipitate formed and the pH was adjusted to about 1011. After the precipitation formation, the stirring continues up to a temperature of 80 °C. The introduction of SDS anionic surfactant induces a homogeneous nuclear process due to considerable size effect of counter-ions on the crystal facets. By adding CTAB as a cationic surfactant there is a complete ionization and cation formation in the tetrahedric structure, but it also determines a control of the growth rates of different faces of the CuO nanoparticles [14, 26]. For all synthesized samples the same synthetic conditions (time, temperature and pH) were maintained. The precipitates thus formed are left in the rest position, then have been filtered under vacuum using a Buchner funnel, and following they were washed with a water-ethanol mixture for purification and removal of the secondary compounds. After washing, the samples were subjected to the drying step in the oven at a temperature of 80 °C, preceded by calcination sintering at a temperature of 550 °C for 3 hours in normal atmosphere. Due to the sintering temperature of the dry samples changed colour from green to blue to black. The functional groups and the chemical bonds of the synthesized oxide samples were analyzed by Fourier Transform Infrared spectrometry (Bruker Optics, Vertex 80V) using the KBr pellet method in the wavenumber range of 4000-400 cm by averaging 64 scans. In the processing of all spectra, the bands attributable to the vibration mode of the C=O bond in CO2 were extracted. In order to investigate the morphology and particle size a Field Emission Scanning electron microscope (FE-SEM), obtained at an operating voltage at 10 kV and a magnitude of 30 000x has been used. X-ray diffraction measurements of the synthesized CuO particles were recorded using a Rigaku Smartlab diffractometer with the radiation CuKa=1.540593 Å, indicating the limit of variation for the current between 150 mA and 190 mA. Data were collected at a scan rate of 12°/min. in the range 20 = 20-95°. Results and Discussion FTIR Spectra The FTIR spectra of the different samples are presented as a comparison between CuO powders obtained in the absence of surfactants (Figure 1a) and in the presence of surfactants (Fig. 1b and c). For all samples treated at 550 °C, bands attributed to both the vibration mode of the Cu-O linkages in the precursor and to the surfactants vibration mode can be seen, thus suggesting the binding of surfactants to particle surface. Band\",\"PeriodicalId\":20390,\"journal\":{\"name\":\"Powder Metallurgy and Advanced Materials\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2018-11-05\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"1\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Powder Metallurgy and Advanced Materials\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.21741/9781945291999-6\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Powder Metallurgy and Advanced Materials","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.21741/9781945291999-6","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 1

摘要

本文以乙酸铜(Cu(CH3COO)2)为碱性前驱体,氢氧化钠(NaOH)为沉淀剂,十二烷基硫酸钠(SDS)和十六烷基三甲基溴化铵(CTAB)分别为阴离子和阳离子表面活性剂,采用共沉淀法成功制备了CuO纳米颗粒。采用傅里叶变换红外光谱(FTIR)、场发射扫描电镜(FESEM)和x射线衍射(XRD)对合成的粉末样品进行了表征。XRD和SEM表征表明,表面活性剂的添加类型对CuO颗粒的形貌、形状和均匀分布都有影响。此外,所有粉末样品的FTIR光谱显示出相同的Cu-O拉伸振动模式,表明存在结晶CuO单斜结构。所得结果为进一步推进氧化铜粉体在各个领域的应用创造了前提。多年来,由于需要获得具有优异物理和化学性能的材料,人们对纳米金属氧化物的开发兴趣大大增加。金属氧化物的合成方法多种多样,研究人员不断开发新的方法,严格控制纳米颗粒的形态、大小和组成,用于多种技术应用。氧化铜(CuO),属于纳米材料类,因其优异的性能、成本效益和广泛的实际应用(太阳能和电化学电池、气体传感器、场发射体、活性催化剂和抗菌活性等)而受到近年来的研究。此外,CuO作为纳米结构氧化物被归类为p型单临床结构半导体材料,其直接带隙值为1.85 eV,引起了特别的关注。这类材料受到特别关注,因为它扩展了电路板的应用范围,如电子和光电子、催化剂、传感器和生物传感器、化学传感装置、纳米流体和场发射器、消炎、化妆品颜料、抗菌剂等[1-4]。为了使该材料在期望的应用领域中表现出可行的性能,拟建立其获得方法及其合成参数;粉末冶金与先进材料- RoPM&AM 2017 Materials Research Forum LLC Materials Research Proceedings 8 (2018) 52-60 doi: http://dx.doi.org/10.21741/9781945291999-6 53迄今为止已经阐述和了解了各种物理和化学方法,如溶胶-凝胶,共沉淀,水热合成,机械混合,固相反应,前驱体热分解,微乳液,微波辐照,物理气相沉积,烧蚀等[3,5,6]。从自下而上的方法来看,沉淀法成本低,适用范围广,且不需要添加二次反应产物[7-9]。特别是,为了获得CuO,该方法涉及在水溶液中沉淀各种可溶性铜盐(硝酸盐、氯化物、硫酸盐和醋酸盐),然后热分解生成氧化物[4,5,10]。将无机盐用NaOH、KOH、(NH4)2CO3或NH4OH溶液在严格的pH控制下,在水介质中混合,最后得到沉淀,进行特征热处理。在合成过程中,反应参数(pH、反应物的加入速度、搅拌速度、溶液浓度、反应温度等)对颗粒的大小、形貌和粒度具有决定性作用[11 - 13]。文献中提出了在相对高温(700 ~ 1100℃)下的各种热处理方法,导致颗粒团聚现象,颗粒平均尺寸增大。为了防止团聚的倾向,有利于纳米结构材料的形成,建议使用表面活性剂。由于静电和硬脂稳定机制降低了溶液的表面张力,改善了纳米晶材料的性能,不同表面活性剂的使用可以改善颗粒的结构、物理化学和形态性能[6,14 - 18]。此外,在氧化材料沉淀过程中加入表面活性剂可以提高纳米颗粒的稳定性以及表面活性剂分子与金属离子之间的相互作用。表面活性剂是一种化学物质,主要作用于相对亲和力较低的表面和可溶解物质。它们具有不对称的分子结构,由非极性(碳氢化合物)和极性(可电离或不可电离)部分组成。 表面活性剂的作用是提供一种有效的涂层,以诱导静电或硬脂排斥,从而抵消范德华引力[19 - 22]。专业文献显示,利用油酸(OA)、聚乙二醇(PEG)、十六烷基三甲基溴化铵(CTAB)、次氯酸十二烷基硫酸酯(SDS)、聚乙烯吡咯烷酮(PVP)、四辛基溴化铵(TOAB)等不同类型的表面活性剂来改善纳米CuO的性能和形成的研究,从初始阶段起就在合成过程中起着重要作用。本研究实验中选择CTAB和SDS两种表面活性剂的原因是基于它们对颗粒稳定性、粒径变化、形貌和沉淀颗粒表面性能的显著影响,同时也因为它们价格低廉,在市场上相对容易找到,毒性低[7,14,23 - 25]。本文研究了在阴离子(SDS)和阳离子(CTAB)两种表面活性剂存在和不存在的情况下,用共沉淀法制备CuO纳米颗粒。研究了表面活性剂对纳米CuO形貌、平均尺寸和晶体结构的影响。利用场发射扫描电镜(FESEM)、x射线衍射(XRD)和傅里叶变换红外光谱(FT-IR)对其形貌和结构进行了表征。粉末冶金与先进材料- RoPM&AM 2017 Materials Research Forum LLC Materials Research Proceedings 8 (2018) 52-60 doi: http://dx.doi.org/10.21741/9781945291999-6 54实验细节:以一水乙酸铜[Cu(CH3COO)2]、氢氧化钠[NaOH]和阴离子型表面活性剂[C12H25NaO4S, SDS 99%]和[C19H42BrN, CTAB > 99%]为原料合成CuO粉末。所有试剂均购自Sigma-Aldrich公司,未经任何纯化。为了在无表面活性剂和有表面活性剂的情况下合成CuO,分别制备了1M [Cu(CH3COO)2]和1M [NaOH]的原液。从乙酸原液中取一部分,在碱性介质中,通过滴加NaOH溶液调节pH,直至观察到形成青蓝色沉淀。在有表面活性剂的样品中,在铜源上加入进样表面活性剂(SDS和CTAB浓度为0.1 M),在连续搅拌的情况下,滴入沉淀剂(NaOH),直至沉淀形成,并将pH调至1011左右。沉淀形成后,继续搅拌至80℃。引入SDS阴离子表面活性剂后,由于反离子在晶面上的尺寸效应,导致了均匀的核过程。通过添加CTAB作为阳离子表面活性剂,在四面体结构中实现了完全的电离和阳离子形成,但也决定了CuO纳米颗粒不同面生长速率的控制[14,26]。所有合成样品均保持相同的合成条件(时间、温度和pH)。这样形成的沉淀物被留在剩余位置,然后用布克纳漏斗在真空下过滤,然后用水-乙醇混合物洗涤,以净化和去除二级化合物。样品洗净后,在80℃的烘箱中烘干,然后在550℃的常压下煅烧烧结3小时。由于干燥样品的烧结温度,颜色由绿色变为蓝色再变为黑色。采用傅里叶变换红外光谱法(Bruker Optics, Vertex 80V)对合成的氧化物样品的官能团和化学键进行了分析,平均扫描64次,波数范围为4000 ~ 400 cm。在所有光谱的处理中,提取了CO2中C=O键的振动模式的能带。为了研究其形貌和颗粒大小,使用了在10 kV工作电压和30 000x量级下获得的场发射扫描电子显微镜(FE-SEM)。合成的CuO粒子的x射线衍射测量使用Rigaku Smartlab衍射仪记录,辐射CuKa=1.540593 Å,表明电流的变化极限在150 mA到190 mA之间。以12°/min的扫描速率收集数据。在20 = 20-95°范围内。不同样品的FTIR光谱是在没有表面活性剂(图1a)和有表面活性剂(图1b和c)的情况下获得的CuO粉末的比较。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Synthesis and characterization of various surfactants for stabilized CuO powder
In the present work, CuO nanoparticles were successfully prepared by the coprecipitation method using copper acetate (Cu(CH3COO)2) as a basic precursor, sodium hydroxide (NaOH) as a precipitator material, sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) as anionic and cationic surfactants, respectively. The synthesized powders samples were characterized by Fourier transform infrared spectrometry (FTIR), field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The investigation showed that the added types of surfactants have effects on the decrease of the crystallite size, on the CuO particles morphology, shape and uniform distribution as it is noticed in the XRD and SEM characterizations. Additionally, the FTIR spectra for all the powders samples showed the same Cu-O stretching vibration mode which indicates the presence of a crystalline CuO monoclinic structure. The obtained results create premises for further advanced the applications of CuO powders in various domains. Introduction Over the years, the interests in developing nanoparticles metal oxides have considerably increased due to the necessity of obtaining materials with outstanding physical and chemical properties. Various methods of metal oxide synthesis have been know so far, researches continue to development a new approaches with a strict control over nanoparticles morphology, size and composition for several technological applications. Copper oxide (CuO), belonging to the nanomaterials class, which has attracted recent research because of its excellent properties, cost effectiveness and wide spectrum of practical applications (solar and electrochemical cells, gas sensors, field emitters, active catalyst and antimicrobial activity, etc.). Also, CuO as nanostructured oxide being classified as a p-type monoclinically structured semiconductor material with a direct band-gap value of 1.85 eV presents a particular attention. This type of material has a special concern because it extends the use in a board range of applications, such as electronics and optoelectronics, catalysts, sensors and biosensors, chemical sensing devices, nanofluids and field emitters, desinfection, cosmetic pigments, antibacterial agent, etc. [1–4]. In order for this material to exhibit viable properties in the desired field of applicability, it is intended to establish its method of obtaining and its synthesis parameters; there Powder Metallurgy and Advanced Materials – RoPM&AM 2017 Materials Research Forum LLC Materials Research Proceedings 8 (2018) 52-60 doi: http://dx.doi.org/10.21741/9781945291999-6 53 have been elaborated and known various physical and chemical methods so far, such as sol-gel, coprecipitation, hydrothermal synthesis, mechanical mixing, solid state reaction, thermal descomposition of precursors, microemulsion, microwave irraditiaon, physical vapor deposition, ablation, etc. [3, 5, 6]. From the bottom-up type methods, precipitation is a cheap one, with applicability on a broadscale, and which does not involve the addition of secondary reaction products [7–9]. Particularly, in order to obtain CuO, the method involves precipitation of various soluble copper salts (nitrates, chlorides, sulphates and acetates) in aqueous solutions, followed by their thermal decomposition with oxide formation [4, 5, 10]. Inorganic salts are mixed in an aqueous medium and under a rigorous pH control by using solutions of NaOH, KOH, (NH4)2CO3 or NH4OH, finally the precipitates obtained are subject to characteristic thermal treatment. In the synthesis process the reaction parameters (pH, rate of addition of reactants and speed of stirring, solution concentration, reaction temperature, etc.) have a determining role in the particle size, morphology and granulometry [11 – 13]. In the literature various thermal treatments at relatively high temperature (between 700 °C and 1100 °C) are presented, leading to the phenomenon of agglomeration and increase of particles average size. To prevent the tendency of agglomeration and to favour the formation of nanostructured materials, the use surfactants have been proposed to be used. The use of different surfactants allows the improvement of particles structural, physico-chemical and morphological properties due to the electrostatic and stearic stabilizing mechanisms that reduce the solutions surface tension and improve the nanocrystalline material properties [6, 14 – 18]. Also, the addition of surfactants in the oxide materials precipitation process leads to increase nanoparticle stability and interaction between surfactant molecules and metal ions. The surfactants are chemical substances, focusing on the surface and solubilized materials with low affinity relative to each other. They have an asymmetrical molecular structure, consisting of a non-polar (hydrocarbon) and a polar (ionisable or non-ionisable) part. The role of surfactants is to provide an effective and efficient coating to induce electrostatic or stearic repulsions that can counterbalance van der Waals attractions [19 – 22]. The specialized literature shows research studies to improve the properties and formation of CuO nanoparticles by using various surfactants of the type of of oleic acid (OA), polyethylene glycol (PEG), cetyltrimethylammonium bromide (CTAB), hypochlorite dodecyl sulphate (SDS), polyvinylpyrrolidone (PVP), tetraoctylammonium bromide (TOAB), playing an important role in the synthesis process steps since the incipient phase. The reason for selecting the two types of surfactants (CTAB and SDS) in the experiments carried out in the present study is based on their remarkable effects on particle stability, size changing, morphology and the surface properties of the precipitated particles, but also because they have low price, can be found relatively easy on the market and have low toxicity [7, 14, 23 – 25]. This paper presents the study of obtaining CuO nanoparticles by the coprecipitation method, in the absence and in the presence of two types of surfactants, anionic (SDS) and cationic (CTAB). It is presented the effect of surfactants on CuO nanoparticles morphology, average size and crystalline structure. The morphological and structural properties are highlighted by using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Fourier transform infrared spectrometry (FT-IR). Powder Metallurgy and Advanced Materials – RoPM&AM 2017 Materials Research Forum LLC Materials Research Proceedings 8 (2018) 52-60 doi: http://dx.doi.org/10.21741/9781945291999-6 54 Experimental details For the synthesis of CuO powders: copper acetate monohydrate [Cu(CH3COO)2], sodium hydroxide [NaOH] and surfactants of type anionic [C12H25NaO4S, SDS 99%] and [C19H42BrN, CTAB > 99 %], were used as starting materials. All reagents were purchased from the company Sigma-Aldrich without any previous purification. For the synthesis of CuO in the absence and in the presence of surfactants the stock solutions of 1M [Cu(CH3COO)2] and 1M [NaOH] were prepared, respectively. From the stock solution of acetate one part is taken and the pH is adjusted in basic medium by adding NaOH solution in dropwise until the formation of a greenish-blue precipitate was observed. In the case of samples with surfactant, over the source of copper the afferent surfactants (SDS and CTAB concentration 0.1 M) was added and under continuous stirring the precipitating agent (NaOH) was adding in dropwise until the precipitate formed and the pH was adjusted to about 1011. After the precipitation formation, the stirring continues up to a temperature of 80 °C. The introduction of SDS anionic surfactant induces a homogeneous nuclear process due to considerable size effect of counter-ions on the crystal facets. By adding CTAB as a cationic surfactant there is a complete ionization and cation formation in the tetrahedric structure, but it also determines a control of the growth rates of different faces of the CuO nanoparticles [14, 26]. For all synthesized samples the same synthetic conditions (time, temperature and pH) were maintained. The precipitates thus formed are left in the rest position, then have been filtered under vacuum using a Buchner funnel, and following they were washed with a water-ethanol mixture for purification and removal of the secondary compounds. After washing, the samples were subjected to the drying step in the oven at a temperature of 80 °C, preceded by calcination sintering at a temperature of 550 °C for 3 hours in normal atmosphere. Due to the sintering temperature of the dry samples changed colour from green to blue to black. The functional groups and the chemical bonds of the synthesized oxide samples were analyzed by Fourier Transform Infrared spectrometry (Bruker Optics, Vertex 80V) using the KBr pellet method in the wavenumber range of 4000-400 cm by averaging 64 scans. In the processing of all spectra, the bands attributable to the vibration mode of the C=O bond in CO2 were extracted. In order to investigate the morphology and particle size a Field Emission Scanning electron microscope (FE-SEM), obtained at an operating voltage at 10 kV and a magnitude of 30 000x has been used. X-ray diffraction measurements of the synthesized CuO particles were recorded using a Rigaku Smartlab diffractometer with the radiation CuKa=1.540593 Å, indicating the limit of variation for the current between 150 mA and 190 mA. Data were collected at a scan rate of 12°/min. in the range 20 = 20-95°. Results and Discussion FTIR Spectra The FTIR spectra of the different samples are presented as a comparison between CuO powders obtained in the absence of surfactants (Figure 1a) and in the presence of surfactants (Fig. 1b and c). For all samples treated at 550 °C, bands attributed to both the vibration mode of the Cu-O linkages in the precursor and to the surfactants vibration mode can be seen, thus suggesting the binding of surfactants to particle surface. Band
求助全文
通过发布文献求助,成功后即可免费获取论文全文。 去求助
来源期刊
自引率
0.00%
发文量
0
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
copy
已复制链接
快去分享给好友吧!
我知道了
右上角分享
点击右上角分享
0
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术官方微信