Electrochemical Synthesis of Cu2O Concave Octahedrons with High

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Electrochemical Synthesis of Cu2O Concave Octahedrons with High-Index Facets and Enhanced Photoelectrochemical Activity Chang Liu, Ya-Huei Chang, Jianan Chen, and Shien-Ping Feng ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.7b12076 • Publication Date (Web): 17 Oct 2017 Downloaded from http://pubs.acs.org on October 17, 2017

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ACS Applied Materials & Interfaces

Electrochemical

Synthesis

of

Cu2O

Concave

Octahedrons with High-Index Facets and Enhanced Photoelectrochemical Activity Chang Liu†, Ya-Huei Chang†, Jianan Chen†, Shien-Ping Feng†, ‡,* †

Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Rd., Hong

Kong ‡

HKU-Zhejiang Institute of Research and Innovation (HKU-ZIRI), Hangzhou, Zhejiang 311300,

China

KEYWORDS: high-index, Cu2O, shape-controlled, concave, photoelectrochemical

ABSTRACT: High-index faceted nano/microcrystals exhibit enhanced catalytic activity and can thus serve as new-generation catalysts as their high density of low-coordinated atoms leads to significantly enhanced catalytic activity. In this study, an effective electrochemical approach termed cyclic scanning electrodeposition (CSE) was developed to convert a thin Cu film into Cu2O concave octahedrons enclosed by 24 {344} high-index facets at room temperature with high yield and high throughput. The formation mechanism and the role of each ion in the electrolyte were systematically studied, which facilitated the design of a high-index faceted metal/metal oxide through CSE. We also presented a general formula to identify the structure of individual crystal

ACS Paragon Plus Environment

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enclosed by {khh} high-index facets based on the crystals oriented along three low-index zone axes and imaged by transmission electron microscopy. Experimental results demonstrated the Cu2O concave octahedrons to be highly efficient, cost-effective catalysts for photoelectrochemical hydrogen production. This new technology is a promising route for the synthesis of metal or metaloxide crystals with high activity and has great potential for several advanced applications, such as clean energy conversion.

INTRODUCTION The development of clean energy conversion processes, such as hydrogen production, electricity generation through fuel cells, and CO2 conversion, relies on a series of electrochemical processes. A major challenge for these technologies is the development of cost-effective and robust catalysts that can effectively catalyze the reactions on the electrode surface. Inorganic microcrystals with high-index facets have attracted considerable attention as potential new-generation catalysts because their high density of low-coordinated atoms (steps, ledges, and kinks) results in considerably enhanced catalytic activity.1-3 Synthesis of high-index faceted microcrystals is challenging because the rate of crystal growth in the direction perpendicular to the high-index plane is considerably faster than that along the low-index plane, thereby causing rapid disappearance of the high-index facets during crystal formation. Recently, there has been growing interest in the controlled execution of concave structures because their negative curvatures are generally enclosed by high-index facets.4 For example, Pt concave nanocubes enclosed by {720} facets exhibited an enhanced electrocatalytic activity 2–4 times higher than that of the Pt cubes and Pt cuboctahedra for oxygen reduction reaction5 and formic acid oxidation.6 Truncated concave


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octahedral Cu2O microcrystals enclosed by 24 {332} facets and 6 {100} facets exhibited 20% improvement in the catalytic oxidation of CO compared with cubic {100} Cu2O microcrystals.[5] Several synthetic methods for synthesizing anisotropic concave metallic or metallic oxide microcrystals have been developed. These methods can be classified into two strategies: selective etching and controlled overgrowth.4, 7 In selective etching, etchants perform at different etching rates on different crystallographic planes and capping agents are used to selectively passivate the specific planes, resulting in a concave structure. In controlled overgrowth, crystal growth is kinetically controlled in a nonequilibrium condition, leading to preferential and directional growth to form a concave structure. However, these synthesis methods typically require complicated procedures, including seed preparation, intermediate purification, and removal of adsorbates (e.g., organic additives, capping agents, and surfactants). Consequently, fabrication is time consuming (10–72 h) and even a subtle change in the reaction temperature or the concentration of adsorbates results in a low production yield with different morphologies.8-10 Using adsorbates may block active sites and introduce heterogeneous impurities, leading to degraded catalytic activity. Moreover, adsorbates have different binding affinities to different metals or metal oxides; therefore, it is challenging to formulate a generic rule for selecting adsorbates for the design of targeted crystals. Although the aforementioned methods are well established in a laboratory environment, they remain unsuitable for industrial production. Therefore, an industrial technique must be developed for the design of different morphologies and the controlled execution of highindex faceted microcrystals. Electrochemical deposition is a widely used industrial process because of its inherently low cost and high throughput. This process has also been recently developed to grow metal microcrystals by controlling potential waveforms and using ions or organic additives.11-12 In this


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study, a new electrochemical approach termed cyclic scanning electrodeposition (CSE) was developed to effectively convert Cu film into Cu2O concave octahedrons enclosed by 24 {344} high-index facets at room temperature with a high yield. The formation mechanism and roles of Ni2+, SO42−, and CH3COO− in the electrolyte were systematically studied, which provided a design rule to tune Cu2O with various shapes through CSE. The effectiveness of the high-index faceted Cu2O microcrystals was demonstrated, and enhanced catalytic activity was observed in photoelectrochemical hydrogen production.

RESULTS AND DISSCUSSION Electrochemical synthesis of high-index faceted Cu2O concave octahedrons Figure 1 is a schematic of the formation of concave octahedral Cu2O microcrystals on the substrates. In this study, fluorine-doped tin-oxide (FTO) glass and a stainless-steel sheet were used as substrates. A 3-mercaptopropyl-trimethoxysilane (MPS) layer was pretreated on the substrates to promote electroplating nucleation because the MPS-grafted substrate can improve the interfacial contact between the metal layer and the substrate.12-15 The hydrolysable methoxy end-group of MPS adheres to the substrate and its sulfur functional group acts as a bridge linking the metal ions in the electrolyte.16-17 A thin Cu layer (Figure 2a) was electroplated on the MPS-grafted substrate and then subjected to CSE in a neutral electrolyte (pH 7.01) consisting of CH3COONa, NiSO4, and Na2SO4. A cyclic scanning potential from −0.75 to 1.45 V in the forward scan was used to strip-off the Cu film from the substrate to generate Cu2+ ions near the electrode, which were immediately re-electroplated on the substrate during the reverse cathodic scan. The entire process of converting the thin Cu film into Cu2O concave octahedrons in a range of 500 nm–1.5 μm was completed in less than 10 min (Figure 2b, c). Cu2O has a cubic crystal structure in which the {100}


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Figure 1. Schematic of the formation of concave octahedral Cu2O microcrystals on the substrates. An MPS layer is formed on the substrate and a Cu layer is then electroplated on the MPS-grafted substrate in Cu electrolyte. During CSE, the Cu layer is stripped from the substrate in an electrolyte comprising CH3COONa, NiSO4, and Na2SO4 in the forward anodic scan, and Cu2+ ions are re-electroplated to form concave octahedral Cu2O microcrystals in the reversed cathodic scan. facet of Cu2O is typically electrically neutral with saturated Cu and O atoms, while and {111} and {110} facets are positively charged with different interfacial arrangement of atoms such that the surface energy of Cu2O is in the sequence of γ100 < γ111 < γ110 < γhkl.10, 18-19 The crystal structure of the concave octahedrons obtained through X-ray diffraction (XRD). The XRD peaks at 2θ of 36° and 42° can be indexed to 111 and 200 peaks of cubic Cu2O phase (JCPDS No. 05-0667) (Figure S1); each Cu2O microcrystal was characterized as a single crystal through electron backscatter diffraction (EBSD) (Figure S2). In addition, CSE can also produce octahedral, truncated octahedral, and plate-like Cu2O microcrystals by changing the additive ions in the electrolyte; this is discussed in the following section. Figures 3a1-c1 present the field-emission scanning electron microscopy (SEM) images of Cu2O concave octahedron in three orientations, suggesting that the concave octahedrons are in an octagonal symmetry and enclosed by 24 identical facets. According to


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Figure 2. SEM images of (a) a Cu layer coated on the MPS-grafted substrate, (b) concave octahedral Cu2O microcrystals formed on the substrate through CSE, and (c) a single concave octahedral Cu2O microcrystal. Steno’s law, Miller indices of high-index facets can be identified by a conjunction of the angle between the facets viewed along an appropriate zone axis.20 Figures 3a2-c2 illustrate the schematic model of a concave octahedron in [111], [110], and [100] zone axes corresponding to the featured projection angles from the three orientations, respectively, where the 24 quadrangular planes are all {344} high-index facets. To confirm the high-index planes, the Cu2O concave octahedron oriented in the zone axes was examined through transmission electron microscopy (TEM) and selective area electron diffraction (SAED). Considering the first row in Figure 3 as an example, the six spots in a six-fold symmetry correspond to the {110} reflections (d-spacing, 3.0 Å) of a Cu2O crystal (Figure 3a4), indicating that the zone axis in Figure 3a3 was [111]. The projection angle of edge-on facets delineated with a red outline was then compared with the schematic model viewed in the same direction. It is noteworthy that the projection angles in the TEM image are in good agreement with the theoretical values of angles in the {344} model (the deficient apex of the Cu2O microcrystal was due to transferring of Cu2O microcrystals from the substrate to the Ni grid when preparing the TEM sample). A comparison between the TEM images and the schematic model in the three primary zone axes confirmed that the concave octahedrons are enclosed by 24 {344} high-index facets.10, 21


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Figure 3. (a1–c1) SEM images of a Cu2O concave octahedron viewed in (a1) [111], (b1) [110], and (c1) [100] orientations. (a2–c2) Schematic model of the Cu2O concave octahedron in three orientations. (a3–c3) TEM images of the Cu2O concave octahedron in three orientations; (a4–c4) Corresponding SAED patterns. Three-dimensional (3D) and two-dimensional (2D) atomic models of the Cu2O crystal are shown in Figure 4. The atomic model projected from the [110] zone axis demonstrates that the {344} facet is periodically composed of three units of {111} at the terrace and one unit of {011} at the step (Figure 4b).4 Figure 4c illustrates the {344} model along the [100] axis; this concave geometry is speculated to be a result of the considerably changed growth rates along the [111] and [100] directions. The ratio (R) given in equation (1) can be used to describe the relationship between the growth rate and the crystal morphology.19, 22 R=

growth rate along [100] direction growth rate along [111] direction

(1)


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For example, the R value of a cube is 0.58 and the R value of an octahedron is 1.73.10, 20 The detailed calculation of the R value for a {344} concave octahedron is presented according to Figure 4d, where α is 35.26° and β is 54.74°. In this case, the γ is 46.69° and the R value is 2.16, indicating that the morphology of Cu2O microcrystals is attributable to the changing growth rate along different low-index facets, which results in fast branching growth along the [100] direction.23 Figure 4d illustrates a mathematical model viewed along the [110] axis for a general concave structure, which is enclosed by {khh} high-index facets in an octagonal symmetric geometry. The relationship between the R values for this type of morphology can be derived as follows:

2k h

(2)

1 2 cos 

(3)

1  tan   tan       2

(4)

tan  =

a

b

R=

V{100} V{111}



1 cos   tan   tan      

(5)

where γ is the projection angle between the {khh} and {100} facets along the [110] direction. In future studies, this model can be used to identify {khh} high-index facets by comparing to the TEM image in an appropriate crystallographic axis.4 Role of each ion in the shape evolution of Cu2O microcrystals The preferential growth is easy to occur in the concave region because the chemical potential of an atom on a concave facet is always lower than that of an atom on a flat facet; this results in the


8

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Figure 4. (a) Unit cell of the Cu2O crystal. (b) Projection of Cu2O crystal in the [110] zone axis, indicating that {433} facets are periodically composed of three units of {111} on the terrace and one unit of {110} at the step. (c) The {344} model along the [100] zone axis. (d) General schematic model projected along the [110] direction used to calculate the R value for the crystal enclosed by {khh} high-index planes. elimination of high-index facets during the growth process.4, 24 The core of CSE is the neutral electrolyte comprising Ni2+, CH3COO−, and SO42− ions, which causes preferential and directional growth17 (the effect of Na+ ions is negligible25). To understand the role of each ion and ion interactions, a series of control experiments were conducted. Figure S3a illustrates the current– potential response of CSE in our standard electrolyte. The first anodic peak marked as A1 (0.54 V) corresponds to the formation of the Cu2O layer.26 The second anodic peak A2 at a potential of 0.97 V corresponds to the oxidation of Cu2O and the dissolution of Cu into Cu2+ ions.26-27 The electrooxidation of Ni2+ to Ni3+ occurring at a potential of 1.1 V is concealed in the broad peak of A2.28 The anodic peak A3 at 1.45 V can be attributed to oxygen evolution.29 A high concentration of


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Cu2+ ions was generated near the electrode after anodic stripping, and Cu2O concave octahedrons were then electroplated at the cathodic peak of C1 (−0.17 V) in the reverse scan.12, 17, 30 The blue curve in Figure S3b represents the current–potential response for the electrolyte without Ni2+ ions; concave octahedral Cu2O with smooth surfaces was produced (Figure S3d). A comparison of the black and blue curves in Figures S3b and c revealed that the absence of Ni 2+ ions results in a decreased current response at the anodic peak A2 for Cu stripping and an increased current response at the cathodic peak C1 for Cu2O formation. Ni2+ facilitated anodic Cu stripping during the anodic scan, and Ni3+ was produced simultaneously, acting as an oxidative etchant during Cu2O formation in the cathodic scan.12

30

To compare the pink curve with black curve in

Figure S3b, the absence of SO42− ions results in a very small anodic peak during Cu/Cu+ oxidation, indicating that SO42− plays a major role in Cu stripping in the forward anodic scan.12 Figure S3e is a photograph showing that the entire Cu film came off after CSE in the electrolyte without SO42−. As indicated by the green curve in Figure S3b, in the absence of CH3COO− ions, a faster dissolution of the Cu film resulted in a higher anodic peak A1. Figure S3f shows that Cu2O truncated octahedrons enclosed by eight hexagonal {111} facets and six square {100} facets were formed when applying CSE in the absence of CH3COO− ions, indicating the importance of CH3COO− ions in the formation of the concave shape. Anions are typically used for selective adsorption on certain crystal planes, blocking or slowing their etching or growth rate to produce high-aspect-ratio structures.22 Herein, the binding affinities and preferential adsorption of different ions were investigated to provide a design rule on tuning the morphologies of Cu2O microcrystals through CSE, as illustrated in Figure 5. SO42− and CH3COO− were the two types of anions in our electrolyte. In 0.1 M Na2SO4 electrolyte (in the absence of CH3COO−), the Cu2O microcrystal was enclosed by eight intact {111} and six


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Figure 5. Schematic with SEM images showing the feasibility of tuning the shape of Cu2O microcrystals using SO42−, CH3COO−, NO2−, and NO3−. The yellow, green, and blue colors represent {111}, {100}, and {344} facets, respectively. imperfective {100} facets at the end potential of −0.2 V; the microcrystal then evolved into truncated octahedrons with eight hexagonal {111} and six square {100} facets at a more negative potential of −0.75 V (Figure S4). This indicates that SO42− stabilizes both {111} and {100} but prefers to adhere to {111} instead of {100}, resulting in a truncated octahedron through thermodynamic growth (uniform growth and near-spherical structure). The introduction of CH3COO− in the electrolyte markedly changed the growth rate of [100]/[111], resulting in an increase in the R value from 900 s under chopped light (light on/off cycle of 20 s).

ASSOCIATED CONTENT Supporting Information The Supporting Information is available free of charge on the ACS Publications website at DOI: XXX. Additional XRD patterns, EBSD maps, SEM images, and electrochemical analysis. AUTHOR INFORMATION Corresponding Author *E-mail: [email protected]


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Notes The authors declare no competing financial interests. ACKNOWLEDGMENT This work was supported by the General Research Fund of the Research Grants Council of Hong Kong Special Administrative Region, China under Award Number 17202314 and 17204516. This work was also partially supported by the Strategic Research Theme on Clean Energy at the University of Hong Kong and HKU-Zhejiang Institute of Research and Innovation (HKU-ZIRI).

REFERENCES (1)

Mohanty, A.; Garg, N.; Jin, R. A Universal Approach to the Synthesis of Noble Metal

Nanodendrites and Their Catalytic Properties. Angew. Chem. Int. Edit. 2010, 49, 4962-4966. (2)

Shegai, T.; Johansson, P.; Langhammer, C.; Käll, M. Directional Scattering and Hydrogen

Sensing by Bimetallic Pd–Au Nanoantennas. Nano Lett. 2012, 12, 2464-2469. (3)

Chen, M.; Tang, S.; Guo, Z.; Wang, X.; Mo, S.; Huang, X.; Liu, G.; Zheng, N. Core–

Shell Pd@ Au Nanoplates as Theranostic Agents for in ‐ Vivo Photoacoustic Imaging, Ct Imaging, and Photothermal Therapy. Adv. Mater. 2014, 26, 8210-8216. (4)

Zhang, H.; Jin, M.; Xia, Y. Noble‐Metal Nanocrystals with Concave Surfaces: Synthesis

and Applications. Angew. Chem. Int. Edit. 2012, 51, 7656-7673. (5)

Yu, T.; Kim, D. Y.; Zhang, H.; Xia, Y. Platinum Concave Nanocubes with High‐Index

Facets and Their Enhanced Activity for Oxygen Reduction Reaction. Angew. Chem. Int. Edit. 2011, 123, 2825-2829.


18

Page 19 of 23

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)

Huang, X.; Zhao, Z.; Fan, J.; Tan, Y.; Zheng, N. Amine-Assisted Synthesis of Concave

Polyhedral Platinum Nanocrystals Having {411} High-Index Facets. J. Am. Chem. Soc. 2011, 133, 4718-4721. (7)

DeSantis, C. J.; Peverly, A. A.; Peters, D. G.; Skrabalak, S. E. Octopods Versus Concave

Nanocrystals: Control of Morphology by Manipulating the Kinetics of Seeded Growth Via CoReduction. Nano Lett. 2011, 11, 2164-2168. (8)

Gole, A.; Murphy, C. J. Seed-Mediated Synthesis of Gold Nanorods: Role of the Size and

Nature of the Seed. Chem. Mater. 2004, 16, 3633-3640. (9)

Sun, Y.; Mayers, B.; Herricks, T.; Xia, Y. Polyol Synthesis of Uniform Silver Nanowires:

A Plausible Growth Mechanism and the Supporting Evidence. Nano Lett. 2003, 3, 955-960. (10)

Sun, S.; Yang, Z. Recent Advances in Tuning Crystal Facets of Polyhedral Cuprous Oxide

Architectures. RSC Advances 2014, 4, 3804-3822. (11)

Hau, N. Y.; Yang, P.; Liu, C.; Wang, J.; Lee, P.-H.; Feng, S.-P. Aminosilane-Assisted

Electrodeposition of Gold Nanodendrites and Their Catalytic Properties. Sci. Rep. 2017, 7, 39839. (12)

Chang, Y.-H.; Liu, C.; Rouvimov, S.; Luo, T.; Feng, S.-P. Electrochemical Synthesis to

Convert a Ag Film into Ag Nanoflowers with High Electrocatalytic Activity. Chem. Commun. 2017, 53, 6752-6755. (13)

Hau, N. Y.; Chang, Y.-H.; Huang, Y.-T.; Wei, T.-C.; Feng, S.-P. Direct Electroplated

Metallization on Indium Tin Oxide Plastic Substrate. Langmuir. 2013, 30, 132-139. (14)

Hau, N. Y.; Chang, Y.-H.; Feng, S.-P. Kinetics Study of Silver Electrocrystallization on

(3-Mercaptopropyl) Trimethoxysilane-Grafted Indium Tin Oxide Plastic Substrate. Electrochim. Acta 2015, 158, 121-128.


19


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

(15)

Page 20 of 23

Chang, Y.-H.; Huang, Y.-T.; Lo, M. K.; Lin, C.-F.; Chen, C.-M.; Feng, S.-P.

Electrochemical Fabrication of Transparent Nickel Hydroxide Nanostructures with Tunable Superhydrophobicity/Superhydrophilicity for 2d Microchannels Application. J. Mater. Chem. A 2014, 2, 1985-1990. (16)

Wu, Q.; Diao, P.; Sun, J.; Jin, T.; Xu, D.; Xiang, M. Electrodeposition of Vertically Aligned

Silver Nanoplate Arrays on Indium Tin Oxide Substrates. J. Phys. Chem. C 2015, 119, 2070920720. (17)

Paunovic, M.; Schlesinger, M., Fundamentals of Electrochemical Deposition. john wiley

& sons: 2006; Vol. 45. (18)

Sun, S.; You, H.; Kong, C.; Song, X.; Ding, B.; Yang, Z. Etching-Limited Branching

Growth of Cuprous Oxide During Ethanol-Assisted Solution Synthesis. CrystEngComm 2011, 13, 2837-2840. (19)

Wang, Z. Transmission Electron Microscopy of Shape-Controlled Nanocrystals and Their

Assemblies. J. Phys. Chem. B. 2000, 104, 1153-1175. (20)

Sun, S.; Kong, C.; Yang, S.; Wang, L.; Song, X.; Ding, B.; Yang, Z. Highly Symmetric

Polyhedral Cu 2 O Crystals with Controllable-Index Planes. CrystEngComm 2011, 13, 2217-2221. (21)

Siegfried, M. J.; Choi, K. S. Electrochemical Crystallization of Cuprous Oxide with

Systematic Shape Evolution. Adv. Mater. 2004, 16, 1743-1746. (22)

Choi, K.-S. Shape Control of Inorganic Materials Via Electrodeposition. Dalton Trans.

2008, 5432-5438. (23)

Xu, J.; Xue, D. Five Branching Growth Patterns in the Cubic Crystal System: A Direct

Observation of Cuprous Oxide Microcrystals. Acta Mater. 2007, 55, 2397-2406. (24)

Cao, G., Synthesis, Properties and Applications. World Scientific: 2004.


20

Page 21 of 23

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


(25)

Siegfried, M. J.; Choi, K.-S. Elucidating the Effect of Additives on the Growth and

Stability of Cu2o Surfaces Via Shape Transformation of Pre-Grown Crystals. J. Am. Chem. Soc. 2006, 128, 10356-10357. (26)

Zaafarany, I.; Boller, H. Electrochemical Behavior of Copper Electrode in Sodium

Hydroxide Solutions. Curr. World Environ. 2009, 4, 277-284. (27)

Zhang, Z.; Wang, P. Highly Stable Copper Oxide Composite as an Effective Photocathode

for Water Splitting Via a Facile Electrochemical Synthesis Strategy. J. Mater. Chem. 2012, 22, 2456-2464. (28)

Tench, D.; Warren, L. F. Electrodeposition of Conducting Transition Metal

Oxide/Hydroxide Films from Aqueous Solution. J. Electrochem. Soc. 1983, 130, 869-872. (29)

Bard, A. J.; Parsons, R.; Jordan, J., Standard Potentials in Aqueous Solution. CRC press:

1985; Vol. 6. (30)

Long, R.; Zhou, S.; Wiley, B. J.; Xiong, Y. Oxidative Etching for Controlled Synthesis of

Metal Nanocrystals: Atomic Addition and Subtraction. Chem. Soc. Rev. 2014, 43, 6288-6310. (31)

Ng, C. H. B.; Fan, W. Y. Shape Evolution of Cu2O Nanostructures Via Kinetic and

Thermodynamic Controlled Growth. J. Phys. Chem. B. 2006, 110, 20801-20807. (32)

Barreca, D.; Fornasiero, P.; Gasparotto, A.; Gombac, V.; Maccato, C.; Montini, T.;

Tondello, E. The Potential of Supported Cu2O and CuO Nanosystems in Photocatalytic H2 Production. ChemSusChem 2009, 2, 230-233. (33)

Paracchino, A.; Laporte, V.; Sivula, K.; Grätzel, M.; Thimsen, E. Highly Active Oxide

Photocathode for Photoelectrochemical Water Reduction. Nature Mater. 2011, 10, 456-461. (34)

Zhang, Z.; Dua, R.; Zhang, L.; Zhu, H.; Zhang, H.; Wang, P. Carbon-Layer-Protected

Cuprous Oxide Nanowire Arrays for Efficient Water Reduction. Acs Nano 2013, 7, 1709-1717.


21


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

(35)

Page 22 of 23

Sun, S.; Song, X.; Sun, Y.; Deng, D.; Yang, Z. The Crystal-Facet-Dependent Effect of

Polyhedral Cu2O Microcrystals on Photocatalytic Activity. Catal. Sci. Technol. 2012, 2, 925-930. (36)

Zhang, L.; Shi, J.; Liu, M.; Jing, D.; Guo, L. Photocatalytic Reforming of Glucose under

Visible Light over Morphology Controlled Cu2o: Efficient Charge Separation by Crystal Facet Engineering. Chem. Commun. 2014, 50, 192-194. (37)

Zhu, C.; Osherov, A.; Panzer, M. J. Surface Chemistry of Electrodeposited Cu2O Films

Studied by Xps. Electrochim. Acta 2013, 111, 771-778. (38)

Kwon, Y.; Soon, A.; Han, H.; Lee, H. Shape Effects of Cuprous Oxide Particles on Stability

in Water and Photocatalytic Water Splitting. J. Mater. Chem. A 2015, 3, 156-162. (39)

Zheng, Z.; Huang, B.; Wang, Z.; Guo, M.; Qin, X.; Zhang, X.; Wang, P.; Dai, Y. Crystal

Faces of Cu2O and Their Stabilities in Photocatalytic Reactions. J. Phys. Chem. C 2009, 113, 14448-14453.


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Electrochemical Synthesis of Cu2O Concave Octahedrons with High

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