Controlled synthesis of CuO nanostructures by a simple solution route

A simple solution route has been developed to prepare nanostructured CuO with Cu(NO₃)₂·3H₂O and NaOH as starting materials. CuO nanoribbons or nanorods and their assemblies into hierarchical structures have been synthesized, respectively, by controlling the molar ratio of NaOH to Cu(NO₃)₂, reaction temperature and the concentration of the starting NaOH solution. Experiments demonstrate that the molar ratio of NaOH to Cu(NO₃)₂ is an important parameter which may decide whether CuO exists in nanoribbons (nanorods) or assemblies into hierarchical structures. Whether Cu(NO₃)₂ is dissolved in ethanol or water also influences the formation of monodispersed CuO nanoribbons (nanorods). The growth mechanism of these nanostructures is discussed. The products were characterized by X-ray diffraction, field-emission scanning electron microscopy and transmission electron microscopy (HRTEM) and their optical absorption spectra were also studied.     

制备方法对CuO/CeO_2-ZrO_2催化CO低温氧化活性的影响

采用微波加热分解法(一步法)和微波加热处理共沉淀+浸渍法(两步法)制备了CuO/CeO2-ZrO2催化剂,并对其进行了X射线衍射、低温氮气吸附/脱附和程序升温还原等表征,采用色谱流动法考察了催化剂的催化CO低温氧化性能.结果表明,一步法比两步法更有利于使催化剂表面CuO高度分散,CuO与CeO2-ZrO2间的相互作用更强,CuO更容易被还原,从而具有更高的催化CO氧化活性.与CeO2-ZrO2有相互作用的高分散和小颗粒CuO有利于催化剂活性的提高,与CeO2-ZrO2无相互作用的大颗粒CuO对催化剂的活性有抑制作用.     

Synthesis of Copper-Based Nanostructures in Liquid Environments by Means of a Non-equilibrium Atmospheric Pressure Nanopulsed Plasma Jet

The influence of the liquid composition on the chemical and morphological properties of copper-based nanostructures synthesized by a non-equilibrium atmospheric plasma treatment is investigated and discussed. The synthesis approach is simple and environmentally friendly, employs a non-equilibrium nanopulsed atmospheric pressure plasma jet as a contactless cathode and a Cu foil as immersed anode. The process was studied using four distinct electrolyte solutions composed of distilled water and either NaCl?+?NaOH, NaCl only or NaOH only at two different concentrations, without the addition of any copper salts. CuO crystalline structures with limited impurities (e.g. Cu and Cu(OH)₂ phases) were produced from NaCl?+?NaOH containing solutions, mainly CuO and CuCl₂ structures were synthesized in the electrolyte solution containing only NaCl and no synthesis occurred in solutions containing only NaOH. Both aggregated and dispersed nanostructures were produced in the NaCl?+?NaOH and NaCl containing solutions. Reaction pathways leading to the formation of the nanostructures are proposed and discussed.     

不同沉淀剂制备CuO-ZnO催化剂甲醛乙炔化反应性能

分别以NaOH、Na₂CO₃、NaHCO₃为沉淀剂,采用共沉淀法制备了Cu：Zn摩尔比为2：1的CuO-ZnO催化剂,利用氢气程序升温还原（H₂-TPR）、热重（TG）、X射线衍射（XRD）及拉曼光谱（Raman）等技术对催化剂进行了表征,结合甲醛乙炔化活性评价,研究了沉淀剂对催化剂结构及催化性能的影响.结果表明,不同沉淀剂对催化剂中活性组分分散度有较大影响,进而在甲醛乙炔化合成1,4-丁炔二醇反应中表现出不同的催化活性.以Na₂CO₃为沉淀剂制备的催化剂中形成CuO-ZnO固溶体,提高了CuO的分散度及Cu⁺在还原性气氛下的稳定性,经活化后可生成较多的活性物种炔化亚铜,表现出最佳的炔化反应活性与1,4-丁炔二醇选择性.     

Preparation,Characterization, and Catalytic Behavior of Nanostructured Mesoporous CuO/ZrO2 Catalysts for Low-Temperature CO Oxidation

High-surface area mesoporous 20 mol% CuO/ZrO₂ catalyst was prepared by a surfactant-assisted method of nanocrystalline particle assembly, and characterized by x-ray powder diffraction (XRD), N₂ adsorption, transmission electron microscopy (TEM), H₂-TPR, TG-DTA, and x-ray photoelectron spectra (XPS) techniques. The catalytic properties of the CuO/ZrO₂ nanocatalysts calcined at different temperature were evaluated by low-temperature carbon monoxide oxidation using a CATLAB system. The results showed that these mesoporous nanostructured CuO/ZrO₂ catalysts were very active for low-temperature CO oxidation and the CuO/ZrO₂ catalyst calcined at 400°C exhibited the highest catalytic activity.     

Conversion of CuO Nanoplates into Porous Hybrid Cu2O/Polypyrrole Nanoflakes through a Pyrrole‐Induced Reductive Transformation Reaction

Porous hybrid Cu₂O/polypyrrole nanoflakes have been synthesized from solid CuO nanoplate templates through the pyrrole‐induced reductive transformation reaction at elevated temperature. The conversion mechanism involves the reductive transformation of CuO to Cu₂O and the in situ oxidative polymerization of pyrrole to polypyrrole. In addition, the morphology of the as‐converted nanohybrids depends on the shape of the CuO precursors. The strategy enables us to transform single‐crystalline CuO nanosheets into hollow hybrid Cu₂O/polypyrrole nanoframes. The ability to transform CuO and an organic monomer into porous hybrid materials of conducting polymer and Cu₂O with macrosized morphological retention opens up interesting possibilities to create novel nanostructures. Electrochemical examinations show that these porous hybrid Cu₂O/polypyrrole nanostructures exhibit efficient catalytic activity towards oxygen reduction reaction (ORR), excellent methanol tolerance ability, and catalytic stability in alkaline solution, thus making them promising nonprecious‐metal‐based catalysts for ORR in alkaline fuel cells and metal–air batteries.     

Room temperature electrochemical synthesis of CuO flower-like microspheres and their electrooxidative activity towards hydrogen peroxide

We describe a facile electrochemical route for the synthesis of CuO flower-like microspheres (CuO FMs) by anodic dissolution of bulk Cu in sodium hydroxide solution at room temperature and without heating. Scanning electron microscopy and X-ray diffraction revealed that the CuO FMs are phase-pure monoclinic crystallites and comprised of CuO nanoflakes. The concentration of NaOH has a large effect on the size of the CuO FMs. The possible formation mechanism is discussed. The CuO FMs are electrocatalytically active towards the oxidation of H₂O₂, and this has resulted in a sensor for H₂O₂. To our knowledge, this is the simplest way to obtain clean CuO FMs.

A glassy carbon electrode modified with poly(anthranilic acid), poly(diphenylamine sulfonate) and CuO nano-particles for the sensitive determination of hydrogen peroxide

We report on a modified glassy carbon electrode (GCE) for sensing hydrogen peroxide (H₂O₂). It was constructed by consecutive electrochemical deposition of poly(anthranilic acid) and poly(diphenylamine sulfonate) on the GCE, followed by the deposition of copper oxide (CuO). The morphology and electrochemistry of the modified electrode was characterized by atomic force microscopy, X-ray diffraction, cyclic voltammetry, and electrochemical impedance spectroscopy. The catalytic performance of the sensor was studied with the use of differential pulse voltammetry under optimized conditions. This sensor displayed significantly better electrocatalytic activity for the reduction of H₂O₂ in comparison to a GCE without or with modification with CuO or polymer films alone. The response to H₂O₂ is linear in the range between 0.005 to ~11 mM, and the detection limit is 0.18 μM (at an S/N of 3).

Study of CuO/Ce0.8Zr0.2O2 catalysts for low-temperature CO oxidation

Summary Copper oxide catalysts supported on Ce_0.8Zr_0.2O₂ were prepared via an impregnation method and characterized by XRD and H₂-TPR techniques. The catalytic activity of the samples for low-temperature CO oxidation was investigated by means of a microreactor-GC system. The influence of calcination temperature, calcination time and different CuO content on the catalytic activity was studied. TPR analysis indicated that well-dispersed CuO was responsible for the low-temperature CO oxidation. The results of the investigation showed that the calcination temperature and CuO loadings had larger influence than the calcination time.     

Intrinsic Peroxidase‐like Activity of Porous CuO Micro‐/nanostructures with Clean Surface

Porous CuO micro‐/nanostructures with clean surface, prepared through Cu₂(OH)₂CO₃ precursor followed by calcination in air, were proven to be an effective peroxidase mimic. They can quickly catalyze oxidation of the peroxidase substrate 3,3′,5,5′‐tetramethylbenzidine (TMB) in the presence of H₂O₂, producing a blue color. The obtained porous CuO micro‐/nanostructure have potential application in wastewater treatment. The apparent steady‐state kinetic parameter was studied with TMB as the substrate. In addition, the potential application of the porous CuO in wastewater treatment was demonstrated with phenol‐containing water as an example. Such investigation not only confirms the intrinsic peroxidase‐like activity of micro‐/nanostructured CuO, but also suggests its potential application in wastewater treatment.     

Effect of the nanoparticle size of supported copper-containing catalysts on their activity in the selective oxidation of CO in an excess of H<Subscript>2</Subscript>

The catalytic properties of systems prepared by the supporting of CuO onto CeO₂, ZrO₂, and Zr_0.5Ce_0.5O₂ with particle sizes of 15–25 nm (nitrate pyrolysis (p)) and 5–6 nm (microemulsion method (me)) in the reaction of CO oxidation in an excess of H₂ were studied. In the latter case, the supports had an almost homogeneous surface and a small number of defects. The catalytic activity of (me) and (p) supports was low and almost the same, whereas the catalytic activity of CuO/(CeO₂, ZrO₂, and Zr_0.5Ce_0.5O₂)(me) samples was lower than that of CuO/(CeO₂ and ZrO₂)(p). The maximum CO conversion (∼100% at 125°C) was observed on 5% CuO/CeO₂ (p). The CO and CO₂ adsorption species on (p) and (me) catalysts were studied by TPD. Differences in the compositions of copper-containing centers on the surfaces of (p) and (me) systems were found using TPR. The nature of the active centers of CO oxidation and the effect of support crystallite size on the catalytic activity were considered.     

Influence of Pd deposition pH value on the performance of Pd-CuO/SiO2 catalyst for semi-hydrogenation of 2-methyl-3-butyn-2-ol（MBY）

The selective hydrogenation of C≡C to C=C bonds is an important step, yet remains to be a great challenge in chemical industry. In this study, we have revealed the influence of Pd deposition pH value on the catalytic performance of Pd-CuO/SiO₂ catalyst for the semi-hydrogenation of 2-methyl-3-butyn-2-ol（MBY）. Trace amount of Pd（about 500 ppm） was loaded via deposition-reduction method on CuO/SiO₂ support by using H₂PdCl₄ solution as precursor and NaBH<...     

Fe2O3含量对Cu-Fe/铝土矿水煤气变换催化剂结构和性能的影响

利用具有高比表面积和介孔结构的改性铝土矿为载体,采用并流共沉淀法制备不同Fe₂O₃含量的Cu-Fe/铝土矿催化剂。以水煤气变换反应为探针反应,考察了催化剂性能。利用X射线荧光元素分析(XRF)、X射线粉末衍射(XRD)、H₂程序升温还原(H₂-TPR)、CO程序升温脱附(CO-TPD)和X射线光电子能谱(XPS)等对催化剂进行了表征。结果表明:负载的Fe₂O₃能显著提高CuO/改性铝土矿催化剂的水煤气变换活性特别是热稳定性能,且随负载的Fe₂O₃含量增加而提高,当负载量为20%时达到最佳。其原因是负载的Fe₂O₃和CuO之间发生了相互作用,形成了类似于CuFe₂O₄复合氧化物,且随负载的Fe₂O₃含量的增加而增强,这种相互作用同时促进了CuO和Fe₂O₃的还原,抑制了CuO的烧结,进而提高了催化剂的性能。     

Fe2O3含量对Cu-Fe/铝土矿水煤气变换催化剂结构和性能的影响

利用具有高比表面积和介孔结构的改性铝土矿为载体,采用并流共沉淀法制备不同Fe2O3含量的Cu-Fe/铝土矿催化剂。以水煤气变换反应为探针反应,考察了催化剂性能。利用X射线荧光元素分析(XRF)、X射线粉末衍射(XRD)、H2程序升温还原(H2-TPR)、CO程序升温脱附(CO-TPD)和X射线光电子能谱(XPS)等对催化剂进行了表征。结果表明:负载的Fe2O3能显著提高CuO/改性铝土矿催化剂的水煤气变换活性特别是热稳定性能,且随负载的Fe2O3含量增加而提高,当负载量为20%时达到最佳。其原因是负载的Fe2O3和CuO之间发生了相互作用,形成了类似于CuFe2O4复合氧化物,且随负载的Fe2O3含量的增加而增强,这种相互作用同时促进了CuO和Fe2O3的还原,抑制了CuO的烧结,进而提高了催化剂的性能。     

超声改性的CuO/Al2O3-MgO催化剂结构 及其超低浓度甲烷催化燃烧性能

采用普通浸渍和超声改性的方法分别制备了CuO/Al₂O₃-MgO催化剂,用于超低浓度甲烷的催化燃烧,并利用SEM、XRD、XPS、H₂-TPR等技术对催化剂进行表征,研究了超声改性作用对催化剂的结构和性能的影响.结果表明,与普通浸渍法制备的催化剂相比,在超声改性的CuO/Al₂O₃-MgO催化剂上,甲烷的转化率得到提高,燃烧特征温度降低.随着超声时间的延长和超声功率的增加,催化剂的催化活性均呈现先增大后减小的趋势;催化剂制备的最佳超声工况为功率150 W、时间20 min.超声改性可使催化剂的比表面积和孔容积增大,表面催化活性较高的Cu⁺浓度增加,活性组分CuO由晶相向非晶相转变、分散度增大,晶粒粒径变小、分布更均匀;这使得甲烷催化燃烧的表观活化能下降、催化剂活性得到增强.     

CuO纳米片催化H2O2氧化降解亚甲基蓝

以十六烷基三甲基溴化铵(CTAB)为保护剂, 采用水热法成功制备了CuO纳米片. 将制备的CuO纳米片在H₂O₂存在下用于催化氧化降解亚甲基蓝, 探讨了其在不同反应条件(如温度、氧化剂浓度及催化剂用量)下对亚甲基蓝降解反应的影响. 该催化反应符合一级动力学模型, 活化能为54.0kJ/mol. CuO纳米片表现出非常高的催化活性, 但其稳定性与重复利用性有待于进一步提高.     

Fruit waste (Pulp) decorated CuO NFs as promising platform for enhanced catalytic response and its peroxidase mimics evaluation

Herein, we report for the first time, an eco-compatible hydrothermal route for the synthesis of carbon enriched mesoporous material (CuO NFs@MP) using fruit waste (Pulp) obtained from Citrus limetta’s (Mausambi) decorated irregular shaped CuO nanoflakes (NFs). The CuO NFs@MP nanocomposite was fully characterized through several spectroscopic-cum-analytical techniques such as TEM and XPS, which further confirmed the presence of CuO NFs. CuO NFs@MP could serve as an excellent catalyst for N-Arylation reaction and also paves promising peroxidase mimic activity. The preliminary results indicated that CuO NFs@MP shows the catalytic advantage of higher yields, shorter reaction time and greener conditions. Simultaneously, the oxidation of colorless TMB with H₂O₂ into blue-green colored ox-TMB was also observed in 60 s with CuO NFs@MP. The present nanocomposite is easy to synthesize, economical, retrievable and a reusable catalyst for synthesizing a varied range of N-Arylated products and could also mimic peroxidase without significant loss of activity.     

CuO超细粉体的形貌与红外特性研究

CuO作为一种多功能精细无机材料，在印染、陶瓷、玻璃及医药等领域的应用已有数十年的历史，作为催化剂的主要活性成分，近年来在氧化、加氢、C１化学合成、NOx还原、CO及碳氢化合物燃烧、精细化工等多种催化反应中也得到了广泛的应用。可以推测，当CuO材料的粒度达到纳米级时，将使它的功能更加独特，应用更为广泛。因此CuO纳米材料的制备方法、聚集状态、与其他组分或载体的作用状况及催化活性等成为当前功能材料发展的研究热点之一犤１～８犦。我们在前文中报道了直接热解Cu２（OH）２CO３所得CuO粒径小、分布均匀、比表面积大，…     

树枝状钯纳米结构的控制合成及硝基苯加氢反应的催化活性

以氯钯酸为前驱体, 苯甲醇为还原剂和溶剂, 十六烷基吡咯烷酮(PVP)为稳定剂, 在微波辐射下制备了分散均匀、形貌均一的树枝状钯纳米结构. 产物用透射电子显微镜(TEM), X射线粉末衍射(XRD), X射线光电子能谱(XPS)进行了表征, 表明所制备的Pd纳米颗粒呈树枝状, 形貌单一, 分散均匀, 是由许多近似圆形的小颗粒自组装而成的二级结构. 对树枝状钯催化硝基苯加氢反应进行探究, 表明树枝状钯的催化活性比市售的钯碳催化剂的催化活性高.