Synthesis of Cu2O Nanotubes with Efficient Photocatalytic Activity by

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Synthesis of CuO Nanotubes with Efficient Photocatalytic Activity by Electrochemical Corrosion Method Qi Wang, Yanlin Jia, Mingpu Wang, Weihong Qi, Yong Pang, Xueming Cui, Wenhai Ji, and Jiang Yi J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/acs.jpcc.5b06213 • Publication Date (Web): 04 Sep 2015 Downloaded from http://pubs.acs.org on September 7, 2015

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The Journal of Physical Chemistry

Synthesis of Cu2O Nanotubes with Efficient Photocatalytic Activity by Electrochemical Corrosion Method Qi Wang1, Yanlin Jia1, 2*, Mingpu Wang1, Weihong Qi1, Yong pang1, Xueming Cui1, Wenhai Ji1, Jiang Yi1

1

School of Materials Science and Engineering, Central South University, Changsha,

410083, P. R. China 2

Department of Metallurgy and Environment, Central South University, Changsha

410083, P. R. China

AUTHOR INFORMATION Corresponding Author * Corresponding authors: [email protected] (Yanlin Jia)

ACS Paragon Plus Environment


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ABSTRACT: Metal oxide nanotubes have been synthesized with varied methods based on mechanisms such as Kirkendall effect, dislocation driven growth and so on. However, most of these methods pose a challenge to these thermally unstable metal oxides. Herein, we firstly adopted the concept of electrochemical corrosion in the successful synthesis of scalable tubular Cu2O nanoparticle (>10 µm in length, 20-500 nm in diameter) in aqueous solution at room temperature. By investigating different growth stages of the reaction process, a CuBrଶି ions diffusion mechanism was rationally put forward associating with literatures, instead of atom diffusion mechanism in Kirkendall effect. The products exhibit outstanding specific surface area and photocatalytical activity. The present method provides a new route for synthesizing metal oxides with hollow structures. 1. INTRODUCTION Hollow-structured metal oxide nanomaterials have attracted increasing research interest in the past decades due to the advantages such as large surface area, lighter weight, saving of material.1 2

They have been extensively applied in areas like chemical storage, nano-reactor, drug delivery

and catalysis.1-3 So far, diversified hollow metal oxide nanoparticles, including ZnO, TiO2, SnO2, MnO2, CuO/Cu2O, Co3O4 and so on, have been successfully synthesized using numerous methods, such as hard templates, soft template, self-assembly methods et al.4-13 Among these methods the sacrificial template-directed chemical transformation method based on Kirkendall effect has been proved to be one of the most effective methods, to synthesize hollow 1D nanostructure metal oxides in particular.9,

14

Reactive sacrificial templates, acted as both

templates and reactive precursors, are free from template removal which has long plagued


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researchers. However, Kirkendall voids on account of the different diffusivities of atoms are in demand of high temperature and long reaction time especially when templates are beyond certain size, which is unfavorable to those poor thermal stable metal oxide.15-18

As a cheap and eco-friendly p-type semiconductor, Cu2O has a direct band gap of about 2.17 eV and a high optical absorption coefficient. These traits allow Cu2O to be used in solar energy conversion, photocatalysis, gas sensors and electrode materials.19-21 Consequently, many efforts have been devoted towards the synthesis of hollow-structured Cu2O. Spherical, octahedral and cubic hollow Cu2O nanocrystals had been successfully prepared.22-24 However, most of these synthesizing routes are not suitable for hollow 1D nanostructure. With reference to Cu2O nanotube, limited success has been achieved by now. Song Jin and co-workers obtained ~95% of Cu2O nanotubes via screw dislocation driven growth process.25 Jin-Hui Zhong and co-workers prepared Cu2O nanotubes by a first formation of Cu2O nanorod and then selectively dissolution of as-formed nanorods.21 R. Nakamura et al. obtained Cu2O nanotubes based on Kirkendall effect by oxidation of Cu nanowires at 423 K for 5.4 ks.17 Here, another challenge is the selective oxidation of Cu to be Cu2O rather than more stable cupric oxide (CuO).

It is widely recognized that the life-span of bulk copper can be greatly shortened in the presence of halide like Clି and Br ି due to electrochemical corrosion, and a great deal of research is available on this subject.26-30 From the conventional viewpoint, the occurrence of electrochemical corrosion is not a desirable process because of its huge



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destruction to metal products. In this paper, electrochemical corrosion has been positively applied as a new synthetic route to design hollow metal oxide nanostructures. High-quality cuprous oxide (>10 µm in length, 20-500 nm in diameter) was synthesized readily in a mild condition at room temperature, which is easy to scale-up. Products containing almost 100% tubular-structure were obtained with high reaction yield (up to 94.4%). The Cu2O nanotubes exhibit far larger specific surface area (54 m2/g) than those reported in most literatures and show outstanding performance while catalyzing degradation of Methyl Orange. 2. EXPERIMENTAL METHOD 2.1 Chemicals and Materials. Sodium hydroxide (NaOH, 97%), Ethylene Diamine

(EDA,

99%), hydrazine hydrate (80%), Copper(Ⅱ) nitrate trihydrate (Cu(NO3)2·3H2O, 99%), Sodium bromide (NaBr, 99%) and Methyl Orange (C13H14N3NaO3S) were purchased from Sinopharm Chemical Reagent Co. Ltd. (Shanghai, China). Hexadecyl trimethyl ammonium Bromide (CTAB, 99%) was purchased from Sigma–Aldrich. All materials were of analytical grade and used as received without further purification 2.2 Material Synthesis Synthesis of Cu Nanowires: Cu nanowires were prepared using a reported method.31 Typically, 1 ml of 0.1 M Cu(NO3) 2·3H2O solution and 1.5 ml EDA was added to a 50 ml conical flask containing 20 ml of 15 M NaOH solution. After 15 minutes’ stirring, 25µl hydrazine hydrate was subsequently added. The flask was immediately capped and stirred for another 1 minutes. The resulting homogeneous mixture was then transferred to 60 ℃


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water bath and incubated for 40 minutes before it was cooled to room temperature. The resulting colloidal products were collected by filtering using 0.2 micron pore size membranes and washed 4 times with deionized water. Actually, the reaction time could varied from 40 minutes to 80 minutes, and the average diameter is directly proportional to the reaction time Synthesis of Cu2O Nanotubes: In a typical synthesis of Cu2O nanotubes, 6.4 mg as-prepared Cu nanowires was dispersed in 50 ml deionized water and sonicated for 15 minutes to get homogeneous-dispersed mixture. 27 mg CTAB was then added and stirred for 60 min at room temperature (25 ℃). The color changed from red to brown and eventually a yellow aqueous solution was acquired. The resulting products were harvested by filtering using 0.2 micron pore size membranes and washed 4 times with ethanol/water mixture. After drying overnight in vacuum in 60 ℃, the product was then stored in a vacuum oven or in cool and dry container in case of oxidation. The reaction yield of this method was obtained by repeating the experiment several times, and the quality of products varied from 6.3 to 6.8 mg, indicating a very high reaction yield. To discuss the growth process, the intermediate state was obtained in 5 minutes and 15 minutes by centrifuging the reactive solution and washed with ethanol quickly. 2.3 Photocatalysis experiments For the photocatalytic activity measurements, 10 mg Cu2O nanotubes and 10 mg commercial TiO2 were dispersed in 100 ml of 20 mg/L aqueous methyl orange solution in a quartz flask. The solution was stirred for 60 min in the dark to make sure the establishment of an adsorption/desorption equilibrium prior to illumination. After that, the flask was transferred to



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25 ℃water bath and irradiated with light from 250W high pressure mercury lamp. About 4 ml of suspension were sampled at a fixed interval of time (20 min). These samples were centrifuged with 12000 rpm to remove the catalyst and then tested with UV-Vis spectrophotometer. 2.4 Characterization Scanning electron microscope (SEM) images were taken on a FEI SIRION200 scanning electron microscope, and the high magnification SEM images were taken on a FEI Helios Nanolab 600i scanning electron microscope. Samples were prepared by dropping ethanol dispersion onto silicon wafers. Transmission electron microscope (TEM), High-resolution transmission electron microscopy (HRTEM) images were carried out on a FEI Tecnai G2 F20 transmission electron microscope. Samples were prepared by dropping ethanol dispersion onto carbon-coated copper TEM grids. All SEM and TEM samples were dried under laboratory conditions. X-ray powder diffraction (XRD) patterns were collected on a Rigaku D/Max 2500 X-ray Powder Diffractometer with Cu-Kα radiation. X-ray photoelectron spectrum (XPS) was obtained by using a Thermo Fisher ESCALAB 250Xi X-ray photoelectron spectrometer. UV-vis absorption spectra were acquired with the aid of BSW spectrophotometer. The BET specific surface area were tested by APAS 2020 (Micromeritics, USA) 3. RESULTS AND DISCUSSION 3.1 Characterization of the Cu nanowires and Cu2O nanotubes The SEM, TEM and HRTEM images shown in Figure S1(A-D) are the Cu nanowires used as templates in the synthesis of Cu2O nanotubes. The XRD pattern in Figure 1(A) shows a representative XRD patterns of copper nanowires used as template (black line)


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and as-prepared Cu2O nanotubes, which are well indexed to FCC copper (JCPDS card, No. 03-1018) and cuprous oxide (JCPDS card, No. 05-0667), respectively. No other characteristic peaks from impurities such as CuO or Cu, were detected in Cu2O nanotubes. Furthermore, XPS was also used to identify the surface composition of nanotubes. The spectrum shown in Figure 1(B) clearly states the signature of Cu 2p and O 1s of Cu2O. More details in Figure 1(C) suggest that the main peaks locate at 952.5 eV and 932.6 eV. It coincides well with the XPS chemical state shifts (dashes in Figure 1(C) represent typical Cu peaks’ location). They can be assigned to 2p1/2 and 2p3/2 of Cu2O in good agreement with data in literature.32 The morphology and structure of the product were further studied using SEM and high-resolution TEM. A typical SEM image of the sonicated nanotubes shown in Figure 2(A), directly indicates that the product consists of uniform tubes and no other morphology is observed. The inset obtained from the broken tubes obviously illustrates that these nanoparticles were hollow. High-magnification SEM image (Figure 2(B)) indicates that the external surface of Cu2O nanotubes was rough. From the low-magnification SEM image shown in Figure S2(A), we can get an overall view of the as-prepared nanotubes and thus acquire the diameter distribution histogram as in Figure S2(B). The diameter of nanotubes ranged from 50nm to 200nm. The relationship between thickness and diameter (Figure S2(D)) was acquired from a large scale measurement of low-magnification TEM images (Figure S2(C)). It reveals that the thickness is in a certain proportion to the diameter in the experimental conditions. That, coupled with Figure



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S2(A,B), demonstrates that nanotubes in a broad range of diameter can be acquired through the use of anticipated template. TEM image shown in Figure 2(C) indicates that their walls were uniform in thickness. The thorny external surface is in accordance with high magnification SEM image (Figure 2(B)). Yet the internal surface is relatively smooth. The high-resolution TEM image shown in Figure 2(D) was taken from the central region of nanotube (region 1 in Figure 2(C)). It is clear that the wall of nanotube composed of multi-Cu2O grains. In addition, these tiny grains are not compact assembled, voids and gaps exist between some grains (as indicated by arrows). These voids provided an efficient route for the outward diffusion of cuprous ion in the process of reaction as well as active sites during catalysis. Figure 2(E) shows high-resolution TEM image taken from the edge of the wall. Voids and gaps are also detected. A lattice-resolved HR-TEM image of the nanotubes is given in Figure2(F). Two sets of fringes with lattice spacing of 2.14 Å and 2.46 Å were observed in the image which is corresponding to the (200) and (111) planes of Cu2O, respectively. The inset shows a Fourier transforms of the image corresponding to the [110] zone axis of the crystal, which further confirmed the phase of products. 3.2 Growth process and chemical mechanism Although the corrosion mechanism of bulk copper in halide medium had been sufficiently studied, it varied from cases.26-30, 33-34 In order to further investigate the chemical mechanism, we have studied the structure evolution in different reaction stages. The initial surface state of copper nanowires were acquired by immediately observation using TEM after washing (Figure


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S3(A, B)).It is observed that a thin oxide layer (~4 nm) covered on copper nanowires, which is inevitable while washing in room temperature according to Cabrera-Mott Theory. The HRTEM images in Figure S3(B) indicates the oxide layer to be cuprous oxide. Due to the existence of this layer, copper nanowires were prevented from further oxidation. Hence intimal Cu nanowires were pretty much the same after stored in medium without bromide for 48 h (Figure S3(C, D)) except for transformation of Cu2O layer to CuO layer. This Cu2O layer becomes a “hard template and initial layer” for later formed nanotubes and prevents a direct penetration of O2 (avoiding inward formation of Cu2O). With reference to the growth process, two growth stages were studied (at 5 min and 15 min, respectively). At the early stage, Cu2O grains formed on Cu2O layer in minutes. Figure 3(B) and Figure 3(C) show representative TEM image and corresponding SAED patterns viewed along the [001] direction of copper template in this period. The clearly observation of two sets of lattice, which belong to Cu and Cu2O, respectively, indicates the initial formation of Cu2O grains. Subsequently, the fresh generated Cu2O deposited on the external surface of Cu2O layer. Consequently, the layer became thicker while the inner diameter remained constantly in the experimental condition. On the other hand, because of the outward-diffusion of Cu ions, voids and holes emerged under the Cu2O layer. In some sites, it went so far as to form segmental tube, as shown in Figure 3(D) and Figure 3(E). The SAED patterns obtained in this stage consist of rings that could be indexed to Cu2O and a square lattice belonging to copper template. Finally, copper



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nanowires exhausted and Cu2O nanotubes formed.Figure 3(A) gives an abridged general view of evolution (the inset shows color change during reactive process). As reported in bulk copper, researchers have extensively acknowledged bromide could penetrate through oxide layer easily.26-29 Local corrosion would take place attributing to anodic polarization of copper in contact with bromide. In these sites, the main process of electrochemical dissolution of copper can be described as follows: ‫ ݑܥ‬+ 2‫ݎܤݑܥ ↔ ି ݎܤ‬ଶି + ݁ ି Where CuBrଶି ion acted as a diffusion particle rather than Cu atom in comparison with Kirkendall effect.14,

35-36

Anodic electrons generated in the process and accumulated in Cu

nanowires. These electrons subsequently transferred to Cu2O layer and eventually captured by dissolved oxygen, and cathodic reaction occurred: ܱଶ + 2‫ܪ‬ଶ ܱ + 4݁ ି ↔ 4ܱ‫ି ܪ‬ A short-circuit corrosion-cell is formed between Cu nanowires and CTAB solution, like what has been depicted in Figure 4. Cu2O deposits on the already formed Cu2O layer when ܱ‫ ିܪ‬reacts with CuBrଶି , and the overall reaction can then be formulated as follows: 2‫ݎܤݑܥ‬ଶି + 2ܱ‫ݑܥ ↔ ିܪ‬ଶ ܱ + ‫ܪ‬ଶ ܱ + 4‫ି ݎܤ‬ The released Br ion can penetrate to Cu nanowires again and bring Cu atoms out just like a “vehicle”. 3.3 BET Analysis and Photocatalytic Activity


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What is also worth to point out is that the surface area of the product is impressive, which could partially attribute to their rough external surface and loose walls. Figure 5(A) shows the N2 adsorption–desorption isotherms of Cu2O nanotubes. The BET surface area is measured to be 53.807 m3/g, which is comparable to the largest surface area of Cu2O nanocrystals (63.4 m3/g).19 Moreover, from the corresponding pore-size distribution curve calculated from the desorption branch by the Barrett-Joyner-Halenda (BJH) method ( Figure 5(B)), two sharp peaks at 4 nm and 7 nm, respectively, were also observed besides a broad peak ranging from 20 nm to 150 nm due to hollow of nanotubes. The mesopore under 10 nm can be attributed to the rough surface and gaps of nanotubes.

Furthermore, the photocatalytic behavior for the degradation of methyl orange (MO) dyes under visible-light irradiation was explored (Figure 5(C)). For comparison, the performance of a commercial P25 TiO2was also investigated. As shown in Figure 4C, it can be distinctly seen that the Cu2O nanotubes exhibited vastly superior photocatalytic activity to commercial TiO2 for the MO degradation reaction when 10 mg of catalyst was used in our degradation experiments (no other addictive added). The Cu2O nanotubes could almost completely degrade 20 mg/L of MO dye in 60 minutes, while P25 could degrade only 3% of MO dye at the same time. In contrast with the most existed photocatalytic experiments of Cu2O, the degradation rate is remarkable (a summary of some previous work, see support information Table S1). Additionally, stability is another significant factor regarding to the catalyst and should be taken into account. Hence, a recycling test was conducted to further investigate the stability of Cu2O nanotubes. As shown in



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Figure 5(D), the product shows no significant loss in activity after 3 cycles 94% of MO could be degraded in 80 min in 3 cycles (though 80 min was needed to completely degrade MO in cycle 2 and cycle 3, but taken slight loss in Cu2O mass and residual MO adsorbing in Cu2O into account, the minor slack is reasonable.). SEM images shown in Figure S5 indicate the morphology change after 3 cycles’ photocatalytic test. An obvious decrease in length (Figure S5(A)) was detected in comparison with the initial stage (Figure S5(B)). It was considered as a result of long time stirring. Slight nanotubes (about 6 broken tubes in 100 tubes，namely 6%）suffered from surface corrosion inevitable (Figure S5(C)). But most nanotubes remained almost the same in surface after test (Figure S5(C)) which is an acceptable result.

4. CONCLUSION For the first time, the concept of nanoscale chemical corrosion was adopted in the synthesis of nanoparticles to the best of our knowledge, and a tubular Cu2O was successfully synthesized with this idea. The advantages of this method are as below: (1) Mild condition. The procedure in our experiment was constantly in a mild aqueous solution at room temperature. The reaction temperature was the lowest in the synthesis of Cu2O so far, which was favorable to the stability of Cu2O. (2) Uniformity. Almost 100% tubular-structure Cu2O nanotubes were obtained and each of these nanotubes was homogeneous in thickness.


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(3) High yield. Reaction yield of 94.5% was obtained through reduplicative experiments. In consideration of product loss during washing, almost all copper nanowires used as templates were transformed to Cu2O nanotubes.

Cooperative techniques were applied to fully understand the composition, structure and evolution of as-prepared products. The Cu2O nanotube shows large surface area and outstanding photodegradation activity in contrast to commercial P25. According to our research, various shapes of hollow Cu2O nanoparticles can be obtained through the use of specific copper template within a certain size range. Furthermore, the novel method proposed in this work may be widely used in synthesis of metallic oxide with hollow structure.

ACKNOWLEDGMENTS

This work was supported by National Nature Science Foundation of China (Grant No. 21373273) and Hunan Provincial Natural Science Foundation of China (Grant No. 13JJ1002).

ASSOCIATED CONTENT

Supporting Information Experimental section, Additional sample characterization including TEM, SEM images of copper nanowires, surface state of copper in different stages (oh and 48 h), measurement of nanotubes, DR-UVS discussion, table of previous work. This material is available free of charge via the Internet at http://pubs.acs.org.



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Corresponding Author *Email: [email protected] (Yanlin Jia)

Notes We declare no competing financial interests.

Reference 1.

Mahmoud, M. A.; Garlyyev, B.; El-Sayed, M. A., Controlling the Catalytic Efficiency on the

Surface of Hollow Gold Nanoparticles by Introducing an Inner Thin Layer of Platinum or Palladium. The Journal of Physical Chemistry Letters 2014, 5, 4088-4094. 2.

Lou, X. W. D.; Archer, L. A.; Yang, Z., Hollow Micro/Nanostructures: Synthesis and

Applications. Advanced Materials 2008, 20, 3987-4019. 3.

Liu, H.; Cooper, V. R.; Dai, S.; Jiang, D, Windowed Carbon Nanotubes for Efficient CO2

Removal from Natural Gas. The Journal of Physical Chemistry Letters 2012, 3, 3343-3347. 4.

Liu, B.; Zeng, H. C., Hollow ZnO Microspheres with Complex Nanobuilding Units.

Chemistry of Materials 2007, 19, 5824-5826. 5.

Wang, Z.; Zhou, L., Metal Oxide Hollow Nanostructures for Lithium‐Ion Batteries.

Advanced materials 2012, 24, 1903-1911.


Page 15 of 25

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


6.

Chang, Y.; Teo, J. J.; Zeng, H. C., Formation of Colloidal CuO Nanocrystallites and Their

Spherical Aggregation and Reductive Transformation to Hollow Cu2O Nanospheres. Langmuir 2005, 21, 1074-1079. 7.

Yu, Y.; Yin, X.; Kvit, A.; Wang, X., Evolution of Hollow TiO2 Nanostructures Via the

Kirkendall Effect Driven by Cation Exchange with Enhanced Photoelectrochemical Performance. Nano letters 2014, 14, 2528-2535. 8.

Ren, S.; Wang, M.; Xu, M.; Yang, Y.; Jia, C.; Hao, C., Fabrication of High-Performance

Supercapacitors Based on Hollow SnO2 Microspheres. Journal of Solid State Electrochemistry 2014, 18, 909-916. 9.

Fan, H. J.; Knez, M.; Scholz, R.; Hesse, D.; Nielsch, K.; Zacharias, M.; Gösele, U.,

Influence of Surface Diffusion on the Formation of Hollow Nanostructures Induced by the Kirkendall Effect: The Basic Concept. Nano letters 2007, 7, 993-997. 10. Wu, R.; Qian, X.; Rui, X.; Liu, H.; Yadian, B.; Zhou, K.; Wei, J.; Yan, Q.; Feng, X. Q.; Long, Y., Zeolitic Imidazolate Framework 67‐Derived High Symmetric Porous Co3O4 Hollow Dodecahedra with Highly Enhanced Lithium Storage Capability. Small 2014, 10, 1932-1938. 11. Sun, D.; Chen, J.; Yang, J.; Yan, X., Morphology and Crystallinity-Controlled Synthesis of MnO2 Hierarchical Nanostructures and Their Application in Lithium Ion Batteries. CrystEngComm 2014, 16, 10476-10484. 12. Meng, F.; Morin, S. A.; Forticaux, A.; Jin, S., Screw Dislocation Driven Growth of Nanomaterials. Accounts of chemical research 2013, 46, 1616-1626. 13. Morin, S. A.; Bierman, M. J.; Tong, J.; Jin, S., Mechanism and Kinetics of Spontaneous



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 16 of 25

Nanotube Growth Driven by Screw Dislocations. Science 2010, 328, 476-480. 14. Fan, H. J.; Gösele, U.; Zacharias, M., Formation of Nanotubes and Hollow Nanoparticles Based on Kirkendall and Diffusion Processes: A Review. Small 2007, 3, 1660-1671. 15. Medford, J. A.; Johnston-Peck, A. C.; Tracy, J. B., Nanostructural Transformations During the Reduction of Hollow and Porous Nickel Oxide Nanoparticles. Nanoscale 2013, 5, 155-159. 16. Nakamura, R.; Lee, J.-G.; Tokozakura, D.; Mori, H.; Nakajima, H., Formation of Hollow ZnO through Low-Temperature Oxidation of Zn Nanoparticles. Materials letters 2007, 61, 1060-1063. 17. Nakamura, R.; Matsubayashi, G.; Tsuchiya, H.; Fujimoto, S.; Nakajima, H., Formation of Oxide Nanotubes Via Oxidation of Fe, Cu and Ni Nanowires and Their Structural Stability: Difference in Formation and Shrinkage Behavior of Interior Pores. Acta Materialia 2009, 57, 5046-5052. 18. Nakamura, R.; Tokozakura, D.; Nakajima, H.; Lee, J.-G.; Mori, H., Hollow Oxide Formation by Oxidation of Al and Cu Nanoparticles. Journal of applied physics 2007, 101, 074303. 19. Wang, J.; Ma, J.; Li, X.; Li, Y.; Zhang, G.; Zhang, F.; Fan, X., Cu2O Mesoporous Spheres with a High Internal Diffusion Capacity and Improved Catalytic Ability for the Aza-Henry Reaction Driven by Visible Light. Chem. Commun. 2014, 50, 14237-14240. 20. Jing, H.-Y.; Wen, T.; Fan, C.-M.; Gao, G.-Q.; Zhong, S.-L.; Xu, A.-W., Efficient Adsorption/Photodegradation of Organic Pollutants from Aqueous Systems Using Cu2O Nanocrystals as a Novel Integrated Photocatalytic Adsorbent. Journal of Materials Chemistry A 2014, 2, 14563-14570.


Page 17 of 25

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


21. Zhong, J.-H.; Li, G.-R.; Wang, Z.-L.; Ou, Y.-N.; Tong, Y.-X., Facile Electrochemical Synthesis of Hexagonal Cu2O Nanotube Arrays and Their Application. Inorganic chemistry 2010, 50, 757-763. 22. Hung, L. I.; Tsung, C. K.; Huang, W.; Yang, P., Room‐Temperature Formation of Hollow Cu2O Nanoparticles. Advanced Materials 2010, 22, 1910-1914. 23. Feng, L.; Zhang, C.; Gao, G.; Cui, D., Facile Synthesis of Hollow Cu2O Octahedral and Spherical Nanocrystals and Their Morphology-Dependent Photocatalytic Properties. Nanoscale research letters 2012, 7, 1-10. 24. Liu, H.; Zhou, Y.; Kulinich, S. A.; Li, J.-J.; Han, L.-L.; Qiao, S.-Z.; Du, X.-W., Scalable Synthesis of Hollow Cu2O Nanocubes with Unique Optical Properties Via a Simple Hydrolysis-Based Approach. J. Mater. Chem. A 2012, 1, 302-307. 25. Hacialioglu, S.; Meng, F.; Jin, S., Facile and Mild Solution Synthesis of Cu2O Nanowires and Nanotubes Driven by Screw Dislocations. Chemical Communications 2012, 48, 1174-1176. 26. Aben, T.; Tromans, D., Anodic Polarization Behavior of Copper in Aqueous Bromide and Bromide/Benzotriazole Solutions. Journal of the Electrochemical Society 1995, 142, 398-404. 27. Brolo, A.; Temperini, M.; Agostinho, S., Effect of Hexamethylenetetramine as a Corrosion Inhibitor for Copper in Bromide Medium. Journal of Electroanalytical Chemistry 1992, 335, 83-92. 28. Brolo, A.; Temperini, M.; Agostinho, S., Copper Dissolution in Bromide Medium in the Absence and Presence of Hexamethylenetetramine (HMTA). Electrochimica acta 1998, 44, 559-571.



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29. Brossard, L., Potentiodynamic Investigation of Copper in the Presence of Bromide Ions. Journal of The Electrochemical Society 1984, 131, 1847-1849. 30. Kear, G.; Barker, B.; Walsh, F., Electrochemical Corrosion of Unalloyed Copper in Chloride Media––a Critical Review. Corrosion science 2004, 46, 109-135. 31. Chang, Y.; Lye, M. L.; Zeng, H. C., Large-Scale Synthesis of High-Quality Ultralong Copper Nanowires. Langmuir 2005, 21, 3746-3748. 32. Wang, W. Z.; Wang, G.; Wang, X. S.; Zhan, Y.; Liu, Y.; Zheng, C. L., Synthesis and Characterization of Cu2O Nanowires by a Novel Reduction Route. Advanced Materials 2002, 14, 67-69. 33. M. Georgiadou, R. A., Modelling of Copper Etching in Aerated Chloride Solutions. Journal of Applied Electrochemistry 1998, 28, 127-134. 34. Plieth, W., Electrochemistry for Materials Science; Elsevier, 2008. 35. Anderson, B. D.; Tracy, J. B., Nanoparticle Conversion Chemistry: Kirkendall Effect, Galvanic Exchange, and Anion Exchange. Nanoscale 2014, 6, 12195-12216. 36. Wang, W.; Dahl, M.; Yin, Y., Hollow Nanocrystals through the Nanoscale Kirkendall Effect. Chemistry of Materials 2012, 25, 1179-1189.


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FIGURE

Figure 1 (A) XRD patterns of copper nanowires (red line) and Cu2O nanotubes (black line). (B) XPS survey spectra of Cu2O nanotubes. (C) and (D) XPS spectra of Cu 2p and O 1s.



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Figure 2 (A) SEM image showing an overview of as-prepared Cu2O nanotubes, magnified in the inset highlighting the tubular structure. (B) High magnification SEM images of external surface. (C) TEM image of Cu2O nanotubes showing the uniformity of tubular structure. (D) HRTEM image of region 1 in (C). (E) High-resolution TEM image taken from the edge of such a nanostructure. (F) Lattice-resolved HRTEM image of region 3. Inset showing Fourier transforms of the image.


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Figure 3 (A) Scheme for the growth of Cu2O nanotubes by electrochemical corrosion. (B, D) TEM images in different reaction time (5min and 15 min). (C, E)SAED patterns corresponding to red site in (B) and (D).



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Figure 4 scheme of electrochemical corrosion mechanism in the process


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Figure 5 (A) Nitrogen adsorption/desorption isotherm and (B) the BJH pore-size distribution curve for Cu2O nanotubes. (C) Photocatalytic activity of as-prepared Cu2O nanotubes and commercial P25 for MO under visible light. (D) Cycling runs in photocatalytic degradation of MO



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FIGURES Figure1 (A) XRD patterns of copper nanowires (red line) and Cu2O nanotubes (black line). (B) XPS survey spectra of Cu2O nanotubes. (C) and (D) XPS spectra of Cu 2p and O 1s. Figure 2 (A) SEM image showing an overview of as-prepared Cu2O nanotubes, magnified in the inset highlighting the tubular structure. (B) High resolution SEM images of external surface. (C) TEM image of Cu2O nanotubes showing the uniformity of tubular structure. (D) HRTEM image of region 1 in (C). (E) High-resolution TEM image taken from the edge of such a nanostructure. (F)

Lattice-resolved HRTEM image of region 3.

Inset showing Fourier transforms of the image. Figure 3 (A) Scheme for the growth of Cu2O nanotubes by electrochemical corrosion. (B, D) TEM images in different reaction time (5min and 15 min). (C, E) SAED patterns corresponding to red site in (B) and (D). Figure 4 scheme of electrochemical corrosion mechanism in the process Figure 5 (A) Nitrogen adsorption/desorption isotherm and (B) the BJH pore-size distribution curve for Cu2O nanotubes. (C) Photocatalytic activity of as-prepared Cu2O nanotubes and commercial P25 for MO under visible light. (D) Cycling runs in photocatalytic degradation of MO


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Synthesis of Cu2O Nanotubes with Efficient Photocatalytic Activity by

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