Preparation of cuprite (Cu2O), paramelaconite (Cu32+Cu21+O4) and tenorite (CuO) with magnetron sputtering ion plating: characterization by EPMA, XRD, HEED and SEM

Cu-O layers were deposited on Si-<100> wafers at 90°?C by means of reactive magnetron sputtering ion plating (R-MSIP). A Cu-target was sputtered in rf-mode by an oxygen/argon plasma, and the influence of the oxygen partial pressure on composition, structure, texture and morphology of the Cu-O layers was investigated. The analysis with EPMA, XRD, HEED and SEM yielded the following results: with an appropriate setting of the oxygen partial pressure, the oxygen content of the films could be controlled between 0 and 50 at-%. XRD bulk structure analysis shows changes in the crystal structure of the films with increasing oxygen content from the fcc structure of Cu, followed by the sc structure of Cu₂O (cuprite), the tetragonal structure of Cu₃ ²⁺Cu₂ ¹⁺O₄ (paramelaconite) to the monoclinic structure of CuO (tenorite). As revealed by HEED, the structure of the near-surface region of the latter two is the same as that of the bulk, whereas in the case of the films with fcc bulk structure, due to oxidation by air, the surface has the sc structure of Cu₂O, and in the case of the film with the sc structure, a monoclinic surface structure of CuO is observed. SEM analyses detected a disordered columnar growth of all Cu-O films.     

One‐Step Hydrothermal Synthesis of a Porous Cu2O Film and Its Photoelectrochemical Properties

A cuprous oxide (Cu₂O) film with a novel porous structure is successfully synthesized on Cu foil by using a simple hydrothermal method. A redox reaction occurs between Cu and Cu²⁺ in aqueous solution to form the Cu₂O film. The porous structures are formed as a result of the Ostwald ripening mechanism. In addition, photoluminescence measurements indicate that the porous Cu₂O film may reduce the recombination of photogenerated electrons and holes. The UV/Vis absorption property of the porous Cu₂O film is better than that of the granular Cu₂O film, and its high photocurrent is expected to make the porous Cu₂O film more suitable for solar energy applications.     

A P/N type compounded Cu<Subscript>2</Subscript>O/TiO<Subscript>2</Subscript> photo-catalytic membrane for organic pollutant degradation

A heterojunction thin film consisting of n-type titanium dioxide (TiO₂) and p-type cuprous oxide (Cu₂O) was fabricated on an FTO conducting glass. The TiO₂ films were grown on the FTO glass by sol–gel and spray pyrolysis methods, and Cu₂O was deposited on it via the hydrothermal method. The morphology, crystalline structure, and optical absorption characteristics were studied by scanning electron microscopy, X-ray diffraction, and ultraviolet–visible diffuse reflectance spectrum, respectively. The results show that the surface of the Cu₂O/TiO₂ film was composed of net and large grains, which contributed to a large specific surface area. The crystal phase of the TiO₂ in the Cu₂O/TiO₂ film remained anatase. The crystal phase of the Cu₂O could not be detected as it is found in traces. The Cu₂O/TiO₂ film had a stronger optical absorption ability than the pure TiO₂ film. To investigate catalytic activity, a photocatalytic degradation experiment of the Cu₂O/TiO₂ film was performed in a homemade thin-layer micro-reactor. The photocatalytic degradation of methylene blue increased with increasing amounts of deposited Cu₂O until a maximum limit was reached. The photocatalytic activity might have declined with an increase in Cu₂O content. The metallic oxide has the potential to screen other photocatalysts from the UV source.     

不同形貌的Cu_2O:可控合成及光学性质(英文)

Cuprous oxide(Cu₂O) hexapodal branch structure with high uniformity was prepared by a solution phase route using sodium dodecyl sulfate as a capping agent. The shapes of Cu₂O crystal(flower-like structure, nanocube and nanoplate) were tuned by varying species and concentrations of surfactants to control the growth rate on different crystal planes of Cu₂O. Cu₂O nanostructures were characterized by UV-Vis spectroscopy, XRD, TEM and SEM. XRD result shows that the obtained Cu₂O belongs to cubic phase. TEM and SEM results demonstrate that specie and concentration of surfactants play a key role in the formation of various morphologies of Cu₂O. The formation mechanism is discussed. Moreover, the optical properties of the obtained Cu₂O are shape-dependent.     

Preparation of cuprous oxides with different sizes and their behaviors of adsorption,visible-light driven photocatalysis and photocorrosion

Cuprous oxide (Cu₂O) nanoparticles and microparticles have been prepared by liquid phase chemical synthesis. The samples were characterized by means of SEM, XRD, UV/DRS and XPS. It was presented that as-prepared Cu₂O nanoparticles are substantially stable in ambient atmosphere and the Cu⁺ as main state exists on the surface of Cu₂O nanoparticles. As-prepared Cu₂O microparticles can exist stably as a Cu₂O/CuO core/shell structure; and the Cu²⁺ as main state exists on the surface of Cu₂O microparticles. The behaviors of adsorption, photocatalysis and photocorrosion of Cu₂O particles with different sizes were investigated in detail. The results show that Cu₂O nanoparticles are very easy to photocorrosion during the photocatalytic reaction, which cannot be used as photocatalyst directly to degrade organic compound, although as-prepared Cu₂O nanoparticles exhibit special property of adsorption. Cu₂O microparticles have a higher photocatalytic activity than Cu₂O nanoparticles because of its slower photocorrosion rate, although Cu₂O microparticles have much lower adsorption capacity than Cu₂O nanoparticles. The mechanisms of photocatalysis and photocorrosion for Cu₂O under visible light were also discussed.     

TiO2/Cu2O Core/Ultrathin Shell Nanorods as Efficient and Stable Photocatalysts for Water Reduction

P‐type Cu₂O has been long considered as an attractive photocatalyst for photocatalytic water reduction, but few successful examples has been reported. Here, we report the synthesis of TiO₂ (core)/Cu₂O (ultrathin film shell) nanorods by a redox reaction between Cu²⁺ and in‐situ generated Ti³⁺ when Cu²⁺‐exchanged H‐titanate nanotubes are calcined in air. Owing to the strong TiO₂‐Cu₂O interfacial interaction, TiO₂ (core)/Cu₂O (ultrathin film shell) nanorods are highly active and stable in photocatalytic water reduction. The TiO₂ core and Cu₂O ultrathin film shell respectively act as the photosensitizer and cocatalyst, and both the photoexcited electrons in the conduction band and the holes in the valence band of TiO₂ respectively transfer to the conduction band and valence band of the Cu₂O ultrathin film shell. Our results unambiguously show that Cu₂O itself can act as the highly active and stable cocatalyst for photocatalytic water reduction.     

A photoelectrochemical study of passive copper in alkaline solutions

The photoelectrochemical behaviour of copper covered with a passivating Cu₂O layer has been studied in alkaline solution. Cu₂O shows the characteristics of a p-type semiconductor with a band gap of 2.3 eV and a flatband potential of −0.28 V (SHE). Its photocurrent spectrum shows the characteristics of the absorption spectrum of Cu₂O films. Several redox systems have been tested, including a CuO layer of the duplex film formed at sufficiently positive potentials. The cathodic photocurrent leads to a reduction of the CuO overlayer to Cu₂O rather than to a self-reduction of Cu₂O to Cu. For the duplex film a decrease of the band gap and an increase of the flatband potential is found, suggesting a participation of CuO in the generation of photoelectrons.     

Cu2O薄膜的可控制备及对次甲基蓝的光催化降解

采用电化学沉积法在掺锡氧化铟(ITO)导电玻璃上通过加入不同添加剂制备了不同形貌的Cu₂O薄膜,利用XPS、XRD、SEM及UV-Vis对Cu₂O薄膜的微观结构、表面形貌及光学特性进行了表征和分析,研究了不同形貌的Cu₂O薄膜在H₂O₂-Cu₂O薄膜体系中对次甲基蓝的降解。结果表明,所制得Cu₂O薄膜为较纯的微米级Cu₂O晶体,作为光催化剂,Cu₂O薄膜3h内对次甲基蓝的降解率均可达92.1%以上。无添加剂的Cu₂O薄膜在前8次重复利用中降解率均可达92.4%以上,利用11次后仍具有较好的光催化活性,降解率可达82.4%。     

Cu2O/g-C3N4催化合成吲哚-2-羧酸酯

我们通过原位还原的方法将吸附在g-C3N4表面上Cu2+还原,制备出Cu2O/g-C3N4复合材料,并利用XRD、SEM、FT-IR、XPS等分析手段表征Cu2O/g-C3N4.表征结果显示:Cu元素主要以Cu2O的形式吸附在g-C3N4载体上.另外,还考察了Cu2O/g-C3 N4在“一锅法”合成吲哚-2-甲酸乙酯的反应中的催化性能.结果表明:即使在较低的催化担载量和温和的反应条件下,Cu2O/g-C3 N4仍能表现出良好的催化性能并获得44.1％的收率.     

Anodic oxidation of foil copper on fiber-glass plastic in sulfate-chloride electrolyte

The effect of the conditions of galvanostatic anodizing of copper foil at fiber-glass plastic on growth kinetic parameters of Cu₂O films is studied. It is shown that the anodic treatment current density in the sulfate-chloride electrolyte features a logarithmic dependence on the electric field strength in the anodic Cu₂O film, which is probably caused by the presence of either a p-n-transition, or an inversion layer of electronic conductivity at the Cu/Cu₂O interface. It is found that the dependence of the film thickness on the formation time at different current densities is nonlinear.     

Improved electrochemical performances of core-shell Cu2O/Cu composite prepared by a simple one-step method

Core-shell Cu₂O/Cu composites were successfully prepared by over-reduction of aqueous CuSO₄ with hydrazine hydrate as reductant. Field emission scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) clearly illuminate that the core is Cu₂O with 400 nm in diameter, and the shell is Cu with about 50 nm in thickness. The core-shell Cu₂O/Cu exhibited weaker polarization and higher coulombic efficiency than pure octahedral Cu₂O, especially in the initial stage of cycles. After 50 cycles, the reversible capacity of Cu₂O/Cu (360 mAh g^?1) was much higher than that of pure Cu₂O (160 mAh g^?1). The improvement of electrochemical properties is attributed to the core-shell structure of Cu₂O/Cu and the catalytic effect of Cu on the decomposition of Li₂O during the charging process.     

Cu2O/CeO2 Photo-electrochemical Water Splitting: A Nanocomposite with an Efficient Interfacial Transmission Path under the Co-action of a p–n Heterojunction and Micro-mesocrystals

Cu₂O is an ideal p-type material for photo-electrochemical (PEC) hydrogen evolution, although serious electron–hole recombination and photocorrosion restrict its further improvement for PEC activity. In this work, CeO₂ nanoparticles (NPs) self-assemble on the surface of Cu₂O octahedra, thus successfully forming a Cu₂O/CeO₂ structure in which p–n heterojunctions and micro-mesocrystals (m-MCs) work together. The optimum Cu₂O/CeO₂ composite, without the use of any cocatalyst, exhibits a fivefold higher photocurrent density (4.63 mA cm⁻² at 0 V vs. the reversible hydrogen electrode) than that of Cu₂O octahedra, which is better than most Cu₂O-based photocathodes without cocatalyst and even comparable with advanced Cu₂O-based photocathodes. The hydrogen production of the optimal Cu₂O/CeO₂ (Faradaic efficiency of ∼100 %) is 17.5 times higher than that of pure Cu₂O octahedra, and the photocurrent shows almost no decay under the 12 h stability test. The delicately designed Cu₂O/CeO₂ structure in this work provides reference and inspiration for the design of cathodes materials.     

金/氧化亚铜异质球的制备及其可见光催化性能

使用L-半胱氨酸作为连接剂, 利用硼氢化钠原位还原预先吸附在介孔氧化亚铜表面的氯金酸根离子,得到了Au/Cu₂O异质结构. 应用X射线粉末衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、X射线光电子能谱(XPS)、紫外-可见(UV-Vis)光谱和N₂物理吸附等手段对催化剂进行表征, 并以λ>400 nm的可见光作为光源, 评价了该催化剂光催化降解亚甲基蓝(MB)的活性. 实验结果表明, 直径为4 nm的金颗粒完好地负载在介孔氧化亚铜的表面, 并且介孔氧化亚铜的细微结构与孔径均未发生变化. 研究表明, 以乙醇作为反应溶剂有效抑制了AuCl₄^-与Cu₂O之间的氧化还原反应, 从而有利于氧化亚铜介孔结构的保持及金颗粒的原位还原. 光催化降解亚甲基蓝的结果表明, Au/Cu₂O异质结构的光催化活性比纯氧化亚铜光催化活性有明显提高. 推测其光催化性能提高的主要原因如下: 一方面, 金颗粒良好的导电性有利于氧化亚铜表面电子的快速转移, 实现电子-空穴分离; 另一方面, 金颗粒可能存在的表面等离子共振现象加速了光生电子的产生.     

Cu2ZnSnS4纳米晶微球的制备及其表征

以乙二醇为溶剂,采用溶剂热法合成出由纳米晶组装而成的Cu2ZnSnS4(CZTS)微球。采用X射线衍射仪(XRD)、拉曼光谱仪(Raman)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、紫外-可见漫反射光谱(DRS)对所得微球的结构与成分、颗粒大小与形貌和光学性质进行了测试分析。研究结果表明:溶剂热法制得的CZTS粉体具有四方晶相结构,微球由纳米晶组装而成,对可见光有良好的吸收;随着反应时间的增加,颗粒尺寸逐渐增大,且对形貌有一定影响;此外,文中还对CZTS微球的形成机理做了推测。     

Selective electrodeposition of ZnO onto Cu2O

The co-deposition of cuprous oxide (Cu₂O) and zinc oxide (ZnO) on indium tin oxide (ITO) substrate was executed by two different electrochemical methods and the formation mechanism of ZnO onto Cu₂O was investigated by ex-situ SEM, XRD, and XPS. The single galvanostatic electrodeposition step in a mixed nitrate electrolyte offered a useful method in preparing ZnO onto triangular Cu₂O islands formed. On the other hand, hexagonal shaped ZnO phase was electrodeposited on ITO substrate as well as on Cu₂O islands when two steps of the galvanostatic and potentiostatic process were applied.     

Ambient Pressure X-ray Photoelectron Spectroscopy Study of Oxidation Phase Transitions on Cu(111) and Cu(110)

The surface structure effect on the oxidation of Cu has been investigated by performing ambient-pressure X-ray photoelectron spectroscopy (APXPS) on Cu(111) and Cu(110) surfaces under oxygen pressures ranging from 10⁻⁸ to 1 mbar and temperatures from 300 to 750 K. The APXPS results show a subsequential phase transition from chemisorbed O/Cu overlayer to Cu₂O and then to CuO on both surfaces. For a given temperature, the oxygen pressure needed to induce initial formation of Cu₂O on Cu(110) is about two orders of magnitude greater than that on Cu(111), which is in contrast with the facile formation of O/Cu overlayer on clean Cu(110). The depth profile measurements during the initial stage of Cu₂O formation indicate the distinct growth modes of Cu₂O on the two surface orientations. We attribute these prominent effects of surface structure to the disparities in the kinetic processes, such as the dissociation and surface/bulk diffusion over O/Cu overlayers. Our findings provide new insights into the kinetics-controlled process of Cu oxidation by oxygen.     

Dense coating of surface mounted Cu<Subscript>2</Subscript>O nanoparticles upon silk fibers under ultrasound irradiation with antibacterial activity

The growth of Cu₂O nanoparticles on silk fibers was achieved under ultrasound irradiation. The effect of temperature, reaction time, ultrasound irradiation and solvent in growth of the Cu₂O nanoparticles upon fiber has been studied. These systems depicted a decrease in the size accompanying a decrease in the reaction time. Particle sizes and morphology of nanoparticle depend on power of ultrasound irradiation. Results show that in presence of ultrasound radiation, particle sizes are in a very low range. The susceptibility of the microorganisms to Cu₂O upon fiber was determined by minimum inhibitory concentration (MIC) using micro dilution method and disk diffusion method. Results suggest that the Cu₂O nanoparticles on silk fibers have antibacterial activity. The Cu₂O nanoparticles upon fibers were characterized with X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM). XRPD analyses indicated that the prepared Cu₂O nanoparticles on silk fibers were crystalline.     

Superior Electrical Conductivity in Hydrogenated Layered Ternary Chalcogenide Nanosheets for Flexible All‐Solid‐State Supercapacitors

As the properties of ultrathin two‐dimensional (2D) crystals are strongly related to their electronic structures, more and more attempts were carried out to tune their electronic structures to meet the high standards for the construction of next‐generation smart electronics. Herein, for the first time, we show that the conductive nature of layered ternary chalcogenide with formula of Cu₂WS₄ can be switched from semiconducting to metallic by hydrogen incorporation, accompanied by a high increase in electrical conductivity. In detail, the room‐temperature electrical conductivity of hydrogenated‐Cu₂WS₄ nanosheet film was almost 10¹⁰ times higher than that of pristine bulk sample with a value of about 2.9×10⁴ S m^?1, which is among the best values for conductive 2D nanosheets. In addition, the metallicity in the hydrogenated‐Cu₂WS₄ is robust and can be retained under high‐temperature treatment. The fabricated all‐solid‐state flexible supercapacitor based on the hydrogenated‐Cu₂WS₄ nanosheet film shows promising electrochemical performances with capacitance of 583.3 F cm^?3 at a current density of 0.31 A cm^?3. This work not only offers a prototype material for the study of electronic structure regulation in 2D crystals, but also paves the way in searching for highly conductive electrodes.     

制备条件对Cu2O结构及甲醛乙炔化性能的影响

以Cu（NO₃）₂·3H₂O为铜源,在液相还原过程中,调变沉淀剂NaOH、还原剂L-抗坏血酸钠的加入顺序制备了Cu₂O,借助X射线粉末衍射（XRD）、傅里叶变换红外光谱（FT-IR）、拉曼光谱（Raman）、俄歇电子能谱（XAES）和H₂程序升温还原（H₂-TPR）等手段研究了制备条件对Cu₂O结构及催化甲醛乙炔化性能的影响.结果表明,调变NaOH及L-抗坏血酸钠的添加方式改变了Cu₂O的结晶度与粒径尺寸,从而使Cu₂O表现出不同的炔化性能.先加入NaOH,后加入抗坏血酸钠,Cu₂O结晶度高,粒径大,难以转化为活性物种炔化亚铜;先加入抗坏血酸钠,后加入NaOH,Cu₂O被过度还原为非活性的金属Cu,两者均造成催化剂活性较低.而NaOH和抗坏血酸钠混合后添加的方式制备出表面Cu₂O结晶完整而体相Cu₂O分散度高的样品,这使得Cu₂O高效转化为炔化亚铜活性物种,表现出最优的炔化性能,在适宜的反应条件下,1,4-丁炔二醇收率达到71.7%,经6次循环后,仍保持在56.5%.     

Influence of substrate nature on the growth of copper oxide thin films

Cu thin films were deposited on Si(111), glass, and quartz substrates by magnetron sputtering. X‐ray diffraction, SEM, and photoemission electron microscope studies were carried out to characterize the films. An influence of the nature of substrate on the Cu₂O and CuO phases formed was observed. Copper silicide formation in case of silicon substrates aided in formation of Cu₂O rather than CuO unlike glass and quartz substrates. Formation of nanocrystallites was observed by SEM and X‐ray diffraction. Copyright © 2016 John Wiley & Sons, Ltd.