In2O3 Nanostructures by

The results revealed that the growth behavior of In(OH)3 was mainly determined by the indium nitrate concentration and applied potential, and well-def...
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Shape-Controlled Growth of In(OH)3/In2O3 Nanostructures by Electrodeposition Dewei Chu,* Yoshitake Masuda, Tatsuki Ohji, and Kazumi Kato National Institute of Advanced Industrial Science and Technology (AIST ), 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560, Japan Received March 24, 2010. Revised Manuscript Received August 11, 2010 In(OH)3 nanostructures with controllable shapes were successfully synthesized using indium nitrate as an indium source by one-step electrodeposition process. The influences of the reaction temperature, time, indium nitrate concentration, and the applied potential on the morphology of the obtained products were discussed in detail. The results revealed that the growth behavior of In(OH)3 was mainly determined by the indium nitrate concentration and applied potential, and well-defined ellipsoids, cubes, and rods could be prepared under suitable conditions. Their possible growth mechanisms as well as photocatalytic applications were addressed. Furthermore, In2O3 nanostructures were obtained from In(OH)3 upon heating, while size and morphology can be maintained during this process.

Introduction Controlled synthesis of micro- and nanoscale materials has attracted increasing interest because of their specific structures and properties that differ from their solid counterparts, as well as potential applications in chemistry, biotechnology, and materials science.1-6 To date, various growth approaches, including vaporand solution-based techniques, have been widely developed to fabricate micro/nanostructures with well-defined morphologies, compositions, and dimensions.3,7-10 Among them, solutionbased methods, such as solvothermal, hydrothermal, and sol-gel processes, have been proven to be more convenient and effective for the synthesis of shape-controllable nanostructures.11-14 Moreover, they have played a key role in understanding the basic crystal growth mechanism. Especially, electrodeposition has unique advantages; for example, it is difficult to obtain nanostructures directly attached on a substrate by a solvothermal or hydrothermal process. Besides, the crystal structure, size, and chemical composition can be controlled easily by monitoring *To whom correspondence should be addressed. Tel: þ81 52-736-7238. Fax: þ81 52-736-7234. E-mail: [email protected]. (1) Subramanian, V.; Gnanasekar, K. I.; Rambabu, B. Solid State Ionics 2004, 175(1-4), 181–184. (2) Murali, A.; Barve, A.; Leppert, V. J.; Risbud, S. H.; Kennedy, I. M.; Lee, H. W. H. Nano Lett. 2001, 1(6), 287–289. (3) Li, Z. H.; Gebner, A.; Richters, J. P.; Kalden, J.; Voss, T.; Kubel, C.; Taubert, A. Adv. Mater. 2008, 20(7), 1279–1285. (4) Oprea, A.; Gurlo, A.; Barsan, N.; Weimar, U. Sens. Actuators, B 2009, 139(2), 322–328. (5) Yoon, J.-H.; Jang, S.-R.; Vittal, R.; Lee, J.; Kim, K.-J. J. Photochem. Photobiol. A 2006, 180(1-2), 184–188. (6) Liu, Z.; Zhang, D.; Han, S.; Li, C.; Tang, T.; Jin, W.; Liu, X.; Lei, B.; Zhou, C. Adv. Mater. 2003, 15(20), 1754–1757. (7) Sun, Y.; Fuge, G. M.; Ashfold, M. N. R. Chem. Phys. Lett. 2004, 396(1-3), 21–26. (8) Chiou, W. T.; Wu, W. Y.; Ting, J. M. Diamond Relat. Mater. 2003, 12(10-11), 1841–1844. (9) Gao, T.; Li, Q.; Wang, T. Chem. Mater. 2005, 17(4), 887–892. (10) Wang, C. Y.; Ali, M.; Kups, T.; R lig, C. C.; Cimalla, V.; Stauden, T.; Ambacher, O. Sens. Actuators, B 2008, 130(2), 589–593. (11) Dev, A.; Panda, S. K.; Kar, S.; Chakrabarti, S.; Chaudhuri, S. J. Phys. Chem. B 2006, 110(29), 14266–14272. (12) Ku, C.-H.; Wu, J.-J. J. Phys. Chem. B 2006, 110(26), 12981–12985. (13) Govender, K.; Boyle, D. S.; Kenway, P. B.; O’Brien, P. J. Mater. Chem. 2004, 14(16), 2575–2591. (14) Chu, D.; Zeng, Y.-P.; Jiang, D.; Masuda, Y. Sens. Actuators, B 2009, 137(2), 630–636.

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current density, electrolyte, and potentials, without using organic solvents or surfactants. However, up to now, a detailed understanding of microstructure design and adjustment by this method is still lacking for the fabrication of nanostructures, as well as resulting property improvements. Indium hydroxide, an important semiconductor with a wide band gap (Eg = 5.15 eV), has drawn much interest because of its semiconductor and optical properties. For example, Yan et al. found that In(OH)3 is a better photocatalyst for the removal of benzene under 254 nm UV light irradiation compared to P25 TiO2.15 On the other hand, indium oxide, which is widely used as a transparent semiconductor oxide, can be fabricated simply by calcining the corresponding indium hydroxide without changing its particle shape.16 Several procedures have been reported for the fabrication of uniform indium hydroxide nanoparticles with different technical routes including hydrolysis of indium nitrate, double-jet precipitation, and the hydrothermal method.17-19 The hydrothermal method, due to its simplicity, high efficiency, and low cost, has been widely adopted to prepare In(OH)3 of various shapes, such as nanosheets, spheres, nanorods, and nanocubes. However, for these In(OH)3 nanostructures, the hydrothermal synthesis routes deal generally with both high pressure and high temperature more than 160 °C and using some toxic and expensive solvents, for example, N,N-dimethylformamide (DMF), ethylenediamine, 1,3-dihydroxybenzene (resorcinol), and formamide.15,20-23 As an alternative, electrodeposition has been (15) Yan, T.; Wang, X.; Long, J.; Liu, P.; Fu, X.; Zhang, G.; Fu, X. J. Colloid Interface Sci. 2008, 325(2), 425–431. (16) Wang, X.; Zhang, M.; Liu, J.; Luo, T.; Qian, Y. Sens. Actuators, B 2009, 137(1), 103–110. (17) Zhang, X.-H.; Xie, S.-Y.; Ni, Z.-M.; Zhang, X.; Jiang, Z.-Y.; Xie, Z.-X.; Huang, R.-B.; Zheng, L.-S. Inorg. Chem. Commun. 2003, 6(12), 1445–1447. (18) Wang, L.; Perez-Maqueda, L. A.; Matijevic, E. Colloid Polym. Sci. 1998, 276(9), 847–850. (19) Lu, X.; Wang, T.; Zhang, X.; Qiu, A.; Cui, D. J. Phys. Conf. Ser. 2009, 188, 012010. (20) Huang, J.; Gao, L. Cryst. Growth. Des. 2006, 6(6), 1528–1532. (21) Tang, Q.; Zhou, W.; Zhang, W.; Ou, S.; Jiang, K.; Yu, W.; Qian, Y. Cryst. Growth. Des. 2004, 5(1), 147–150. (22) Zhuang, Z.; Peng, Q.; Liu, J.; Wang, X.; Li, Y. Inorg. Chem. 2007, 46(13), 5179–5187. (23) Yin, W.; Su, J.; Cao, M.; Ni, C.; Cloutier, S. G.; Huang, Z.; Ma, X.; Ren, L.; Hu, C.; Wei, B. J. Phys. Chem. C. 2009, 113(45), 19493–19499.

Published on Web 08/23/2010

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applied to prepare In(OH)3 nanostructures under mild conditions, while the morphology control has not been addressed.24 Herein, a systematic study of the controlled synthesis of indium hydroxides and indium oxides nanostructures has been carried out by electrodeposition. The optimum synthesis condition, structure, and morphology variation of the nanostructures were investigated, The possible growth mechanism as well as the photocatalytic properties of the as-obtained In(OH)3 were studied.

Experimental Section For In(OH)3, electrodeposition was carried out using an aqueous solution containing In(NO3)3 3 3H2O (99% purity, Wako) by constant potential deposition at 65-85 °C using a HA151 Potentiostat (Hokuto Denko Corp.). A standard three-electrode setup in an undivided cell was used. Tin-doped indium oxide (ITO, 14 Ω, Asashi Glass Corp., Japan, 1.1 mm  26 mm  30 mm) was used as the working electrode, while platinum foil (0.2 mm  10 mm  20 mm) was used as the counterelectrode. The distance between the two electrodes was 30 mm. The reference electrode was an Ag/AgCl electrode in 4 M KCl solution, against which all of the potentials reported herein were measured. After deposition, the film was washed by water and dried in air at 80 °C for 10 h. To obtain In2O3, the film was then heated at 300 °C for 30 min in air. The phase composition of the samples was characterized by X-ray powder diffraction (XRD, RINT-2100 V, Rigaku, Cu KR). The morphologies of the samples were observed by field emission scanning electron microscopy (FESEM; JSM-6335FM, JEOL, with an accelerating voltage of 5 kV) and transmission electron microscopy (TEM, JEM-2010, JEOL). The photocatalytic activity of as-prepared In(OH)3 for decomposing methylene blue (MB) in aqueous solution was investigated by the bleaching of dye in solution. In a typical measurement, 8 mg of In(OH)3 (scratched from the substrate) was put into a glass reactor with 50 mL of MB aqueous solution, and the initial concentration of MB was 20 mg L-1. The reactor was then kept in the dark with agitation for 30 min to obtain adsorption equilibrium, prior to light irradiation by a 110W UV lamp (SUV110GS36, SEN Light Corp.). The efficiency of the degradation processes was evaluated by monitoring the dye decolorization at the maximum absorption around λ = 663 nm as a function of irradiation time in the separated MB solution with a UV-vis spectrometer (JASCO V-670).

Results and Discussion The electrochemical synthesis of indium hydroxide is a two step process: First, nitrate ions and H2O are electrochemically reduced at the surface of the working electrode, resulting in an increase in local pH value in the vicinity of the electrode (eqs 1 and 2). Then, the increase in the local pH leads to the precipitation of indium ions as indium hydroxide (eq 3) at suitable temperatures: NO3 - þ H2 O þ 2e - f NO2 - þ 2OH -

ð1Þ

for -0.20 V versus Ag/AgCl 2H2 O þ 2e - f H2 þ 2OH -

ð2Þ

for -1.05 V versus Ag/AgCl In3þ þ 3OH - f InðOHÞ3

ð3Þ

The linear sweep voltammetry of In(OH)3 deposition from 0.05 M In(NO3)3 solution at 85 °C in our case showed that it was (24) Lei, Z.; Ma, G.; Liu, M.; You, W.; Yan, H.; Wu, G.; Takata, T.; Hara, M.; Domen, K.; Li, C. J. Catal. 2006, 237(2), 322–329.

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Table 1. Experimental Conditions Used in Preparation of In(OH)3 with Different Morphology [In3þ] (M)

potential (V)

temperature (°C)

time (min)

structure

0.05 0.05 0.05 0.008 0.008 0.008 0.008

-1.2 -1.0 -1.0 -1.2 -1.2 -1.2 -0.8

85 85 65 85 65 85 85

60 60 60 60 60 20 20

hollow sphere hollow sphere ellipsoid cube sheet cube rod

difficult to electrodeposit In(OH)3 on the substrate at an electrode potential higher than -0.6 V due to too low of a current density. In this case, we chose -0.8, -1.0, and -1.2 V as the cathodic potentials, and different In(OH)3 nanostructures, including ellipsoids, cubes, and rods, were obtained by tuning reaction parameters. Table 1 lists the morphology of the products prepared under different conditions. Figure 1 shows the SEM images of In(OH)3 nanostructures synthesized in various conditions. As to the sample deposited at a potential of -1.0 V, from 0.05 M In(NO3)3 solution at 65 °C for 1 h, In(OH)3 ellipsoids with the average horizontal axis of 0.6 μm and longitudinal axis of 1 μm can be found, which is shown in Figure 1a. The high magnification SEM image in Figure 1b indicates that the surface of the ellipsoid is rough. The inset figure shows an imperfect ellipsoid, which is composed of assembled nanosheets. In contrast, In(OH)3 microcubes with a size of ∼0.6 μm (Figure 1c) are synthesized at low In3þ concentrations ([In3þ] = 0.008M) at 85 °C and -1.2 V for 1 h. The surface of the cube is smooth with stacking defects, and the cube is simply enclosed with crystal faces of {001} surfaces,15 which can be found in the enlarged SEM image (Figure 1d). Alternatively, In(OH)3 rod arrays with diameters of about 160 nm are deposited under -0.8 V at 85 °C for 20 min (Figure 1e,f). Thus, it is found that the morphology of deposited In(OH)3 can be controlled by electrochemical parameters. Additional experiments were comparatively designed to analyze the most important variables for these three kinds of nanostructures. For In(OH)3 ellipsoids, if the reaction temperature was increased to 85 °C, large hollow spheres with an average diameter of 0.8 mm were obtained, the hollow structure was clearly revealed from a broken sphere, and the wall of the spheres was composed of ellipsoids (Supporting Information, Figure S1). According to eq 2, if the applied potential arrives at 1 V, H2 bubbles are generated on the electrode surface. The release of H2 bubbles can act as a template for the formation of hollow structure. Meanwhile, the evolution of H2 (eq 2) would be very slow at low temperature (65 °C); thus, only In(OH)3 ellipsoids were obtained. If increasing the applied potential to 1.2 V, hollow spheres with larger diameter can be found. As to the cubes, when the electrodeposition temperature was set at 65 °C, only a small amount of cubes was obtained, and most of the samples were nanosheets (Supporting Information, Figure S2). From these results, it can be found that the In3þ concentration plays a crucial role in the control of In(OH)3 nanostructures. Briefly, for the electrodeposition solution with different In3þ concentrations, the pH value and current density would be different. In the parallel experiment of In(OH)3 rods, the applied potential was set as -1.2 V. Interestingly, microcubes were also obtained (Supporting Information, Figure S3). This result implies that the applied potential also determines the growth behavior of In(OH)3. Further characterization for In(OH)3 nanostructures was performed with TEM. It can be seen from Figure 2b that the In(OH)3 DOI: 10.1021/la102255k

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Figure 1. SEM images of In(OH)3 prepared at different conditions: (a and b) -1.0 V, 0.05 M In3þ, 65 °C for 1 h; (c and d) -1.2 V, 0.008 M In3þ, 85 °C for 1 h; and (e and f) -0.8 V, 0.008 M In3þ, 85 °C for 20 min.

ellipsoid consists of highly parallel nanosheets. The lattice plane spacing between the adjacent lattice planes is 0.282 nm, which is consistent with the {220} d-spacing of cubic In(OH)3. The inset in Figure 2b is an SAED pattern of the ellipsoid, where the spotty rings can be indexed as {220} and {440} reflections. The results indicate that the main surface of the nanosheets is the (220) lattice plane. Similarly, a HRTEM image of the In(OH)3 cube in Figure 2d shows {220} d-spacing. However, in the corresponding SAED pattern, clear {200} reflections are observed, implying that the cube is enclosed by {200} planes. In addition, the truncations of the cube at {220} facets are also observed. Combined with Figure S2 in the Supporting Information, it is reasonable to deduce that the conversion of the nanosheets into cubes occurs during electrochemical deposition. As to In(OH)3 nanorods, it can be clearly seen in Figure 2f that the nanorod is composed of nanosheets with multilayers. The (200) plane in the corresponding SAED pattern is perpendicular to the longitudinal axis of the rod, indicating the growth direction of [100]. The XRD patterns of the as-prepared ellipsoids, cubes, and rods are shown in Figure 3a, in which all of the peaks can be indexed as a pure, cube phase of In(OH)3 (JCPDS card 76-1463), 14816 DOI: 10.1021/la102255k

with lattice constants of a(ellipsoids) = 0.7974 nm, a(cubes) = 0.7974 nm, and a(rods) = 0.7957 nm, which agrees with the literature value of a = 0.7974 nm (JCPDS card 76-1463). The strong and sharp diffraction peaks reveal that the samples are well crystallized. Specially, for rods, the relative intensity of (200) peak is much stronger than that of other peaks, indicating that the rods have a preferred orientation along the [100] direction, which is consistent with SEM and TEM observations. Generally, the electrodeposition process of In(OH)3 can be described at the atomic level as different stages: The first involves the formation of stable nuclei, consisting of the motion of In3þ ions from the electrolyte to the cathode, electron transfer and the formation of adsorbed atoms, and finally the grouping of atoms to form a stable In(OH)3 nucleus. The second stage consists of the isolated growth of individual In(OH)3 nuclei through the incorporation of new atoms, the merging of nuclei, and the formation of continuous layers (nanosheets) over the cathode. The nanosheets are small and not thermodynamically stable for crystal growth. As a result, the adjacent nanosheets are self-assembled by sharing a common crystallographic orientation. The elimination of the pairs of high energy surfaces would result in a substantial Langmuir 2010, 26(18), 14814–14820

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Figure 2. TEM and HRTEM images of In(OH)3 prepared at different conditions: (a and b) -1.0 V, 0.05 M In3þ, 65 °C for 1 h; (c and d) -1.2 V, 0.008 M In3þ, 85 °C for 1 h; and (e and f) -0.8 V, 0.008 M In3þ, 85 °C for 20 min.

Figure 3. XRD patterns of as-deposited (a) In(OH)3 and (b) In2O3. Langmuir 2010, 26(18), 14814–14820

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reduction in surface free energy. After the nanosheets are assembled to a stable size, they will grow by combining with smaller

Figure 4. Schematic representation of the formation process of In(OH)3 ellipsoids, cubes, and rods.

Figure 5. Concentration changes of MB as a function of irradiation time with In(OH)3 ellipsoids, cubes, and rods, respectively.

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unstable nuclei. In this case, the final crystal morphology is determined by the degree of supersaturation, the diffusion of the unstable nuclei to the surface of the crystals, surface, and interfacial energy, and the crystal structure. This kind of growth mode could lead to the formation of faceted particles or perfect anisotropic crystals if there is a sufficient difference in the surface energies for different crystallographic faces. In the cubic In(OH)3 structure, the {001} planes contain three equivalent planes, (100), (010), and (001), which are perpendicular to three directions, [100], [010], and [001], respectively. Consequently, the cubic morphology of the sample enclosed with {001} surfaces is obtained. The formation of various In(OH)3 nanostructures, including ellipsoids and rods, could be explained by the different crystal growth surroundings. Figure 4 shows a schematic representation of the formation process of ellipsoids, cubes, and rods. As to the synthesis of In(OH)3 ellipsoids, the concentration of indium nitrate is much higher than that of cubes, which means a lower pH value in the reaction solution. Thus, the concentration of OHalso would be lower, resulting in a lower nucleation rate of In(OH)3. Under this condition, the collision rate between In(OH)3 nanosheets is much quicker than the growth rate of a single In(OH)3 crystal in solution, so ellipsoid-like agglomerates composed of small nanosheets are obtained through random aggregation for minimizing surface energy. For In(OH)3 rods, the formation of rod structure can be attributed to preferential onedimensional orientation of the nanosheets along the [100] growth direction at an early stage. In this case, it is suggested that the relatively low potential (-0.8 V) might play an important role in deciding the final morphology. During electrodeposition, the working electrode is parallel to the counter electrode, and thus, the electric field can be regarded as perpendicular to the substrate. At a relatively low deposition rate (-0.8 V), the atomic arrangement rate along the electric field direction would be increased, resulting in preferential growth perpendicular to the substrate and formation of a rod structure. Therefore, the growth rate of [100] is

Figure 6. SEM images of In2O3 (a and b) ellipsoids, (c) cubes, and (d) rods. 14818 DOI: 10.1021/la102255k

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Figure 7. TEM and HRTEM images of In2O3 (a and b) ellipsoids, (c and d) cubes, and (e and f) rods.

faster than that of [010] and [001]. However, a relatively high deposition rate (corresponding to -1.2 V) would not give the atoms time to arrange their sites. Because the surface of the substrate was not smooth, the electric field would have random orientations. As a result, the growth rate of [100], [010], and [001] would be almost the same. In recent years, there have been many reports in the application of semiconductors as photocatalysts.15,24,25 For example, S-doped In(OH)3 was shown to be a visible light-driven photocatalyst.24 Herein, the photocatalytic activity of as-prepared In(OH)3 nanostructures on MB degradation was also investigated. Figure 5 indicates comparison of the conversion of MB over In(OH)3 ellipsoids, cubes, and rods, where the cubes show the highest photocatalytic activity, and more than 86% of MB molecules were decomposed in 75 min. Usually, the difference in photocatalytic activities may arise from differences in surface areas, polar planes, or oxygen vacancies. In this work, the size of rods is smaller, (25) Wen, Z.; Wang, G.; Lu, W.; Wang, Q.; Zhang, Q.; Li, J. Cryst. Growth Des. 2007, 7(9), 1722–1725.

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indicating a higher surface area. Thus, there was no correlation between the surface areas and the catalytic activity, which demonstrates that there are other more important factors that determine activities. Basically, the difference of surface atomic structures results in a distinct photocatalytic ability. Unstable surfaces with high surface energy are easier to be attacked by holes and thus show lower quantum yield than those with low surface energy. It is noticed that among three kinds of samples, In(OH)3 cubes are bound by {001} surfaces, which were predicted to have the lowest surface energy. Therefore, this kind of cube nanostructure is more stable as compared to others and shows the best photocatalytic activity. In2O3 can be obtained by calcining as-prepared In(OH)3. Figure 3b shows the XRD patterns of the samples calcined at 300 °C for 30 min. All of the peaks can be indexed to a cubic lattice of pure In2O3 (JCPDS 71-2194). No additional peaks of other phases have been found, and the peaks of all of the samples are broadening, implying small crystallite sizes. It is worth noting that the broadening phenomena is not observed in In(OH)3 samples. Therefore, it can be deduced that In(OH)3 ellposids, DOI: 10.1021/la102255k

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cubes, and rods would be decomposed into small In2O3 particles after calcining. The overview morphology of In2O3 nanostructures obtained from In(OH)3 ellipsoids, cubes, and rods was observed by SEM. Figure 6 indicates that the initial shape and size of the ellipsoids and rods were basically kept the same as the precursors In(OH)3, except that there are some cracks on the cubes, as shown in Figure 6c. The results are inconsistent with the XRD results shown in Figure 3. Thus, further structural characterization of the products was performed by TEM. The TEM image of a single In2O3 ellipsoid in Figure 7a reveals the unusual texture of the particle, which are built up of numerous small nanoparticles roughly 5 nm in size. It seems that these primary small nanoparticles interconnected with each other to form larger secondary ellipsoidal architectures with recognizable boundaries. The highresolution TEM image of the ellipsoid in Figure 7b clearly shows the obvious aggregation of small nanoparticles and lattice planes with perfect crystallinity. The lattice plane spacing of different particles is 0.292 nm, which is consistent with the separation of (222) planes of cubic In2O3. This result indicates that [111] is the preferred crystallization direction for In2O3 ellipsoids, and this can be explained by the fact that the surface energy relationships among the low-index crystallographic planes are γ{111} < γ{100} < γ{110}. As to the cubes shown in Figure 7c, the cube structure was partly collapsed, and an irregular edge was found, which agrees with SEM observations. The collapse of In(OH)3 cubes can be attributed to H2O evaporation during the decomposition process. However, no collapsing phenomena are observed in In2O3 ellipsoids and rods, which suggests that In(OH)3 cubes are single crystalline, and there are no interconnected pores in the cubes. This assumption is supported by Figure 7d, where HRTEM image of a part of the one cube shows clear lattice

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planes of (222) corresponding to single crystalline In2O3. From Figure 7e, it can be found that In2O3 rods are also composed of small particles. The HRTEM image of the corresponding rod shows lattice planes of (222) with high crystallinity. Most of the planes are parallel to the growth direction, indicating imperfect orientated attachment.

Conclusion In summary, In(OH)3 nanostructures with ellipsoid, cube, and rod shapes were successfully synthesized via template and surfactant-free electrodeposition in aqueous solution. The results suggest that In3þ concentration and applied potential play critical roles in the morphology of In(OH)3 nanostructures. The formation of different nanostructures can be explained by initial selfassembly of In(OH)3 nanosheets and a subsequent ripening process under various conditions. It is found that In(OH)3 cubes show better photocatalytic activity for MB degradation, suggesting that the photocatalytic properties of In(OH)3 are strongly dependent on the surface structure. In addition, corresponding In2O3 nanostructures can be obtained by dehydration of In(OH)3. In all cases, the crystallization direction is [111], although the cube structure is partly collapsed. These studies may supply the basis of novel nano/micro building blocks and more importantly the success of bottom-up approaches toward further devices. Acknowledgment. This work was supported by the Ministry of Economy, Trade and Industry (METI), Japan, as a part of the Environmentally Friendly Sensor Project. Supporting Information Available: SEM images of In(OH)3 obtained from different conditions. This material is available free of charge via the Internet at http://pubs.acs.org.

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