Nano Res

1

Shape-Controlled Growth of SrTiO3 Ployhedral

Nanocrystals

Lingqing Dong1,2,†

, Hui Shi3,†

, Kui Cheng1,†

, Qi Wang3, Wenjian Weng

1,4() and Wei-Qiang Han

2()

Nano Res., Just Accepted Manuscript • DOI: 10.1007/s12274-014-0495-y

http://www.thenanoresearch.com on May 12, 2014

© Tsinghua University Press 2014

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Nano Research

DOI 10.1007/s12274-014-0495-y

Shape-Controlled Growth of SrTiO3 Polyhedral

Nanocrystals

Lingqing Dong1,2, Hui Shi3, Kui Cheng1, Qi Wang3,

Wenjian Weng1,4, & Wei-Qiang Han2,

1,3 Zhejiang University, China.

2 Ningbo Institute of Materials Technology &

Engineering, Chinese Academy of Sciences, China.

4 Shanghai Institute of Ceramics, Chinese Academy of

Sciences, China.

The concentration and pKa value of the alcohol molecules both play

important roles in determining the size and shape of the SrTiO3

polyhedral nanocrystals. The adsorption energy of alcohol molecules

on SrTiO3 {110} facet is decided by their pKa values, which are

critical for morphology control.

Shape-Controlled Growth of SrTiO3 Ployhedral

Nanocrystals

Lingqing Dong1,2,†

, Hui Shi3,†

, Kui Cheng1,†

, Qi Wang3, Wenjian Weng

1,4() and Wei-Qiang Han

2()

Received: day month year

Revised: day month year

Accepted: day month year

(automatically inserted by

the publisher)

© Tsinghua University Press

and Springer-Verlag Berlin

Heidelberg 2014

KEYWORDS

SrTiO3, BaTiO3,

shape-controlled growth,

alcohol molecules, pKa

values

ABSTRACT

A series of SrTiO3 polyhedral nanocrystals with systematic morphology

evolution from cubic to edge-truncated cubic and truncated rhombic

dodecahedra have been synthesized by using a series of alcohol molecules with

different acidities as surfactants. The concentration and pKa value of the

alcohols both play important roles in determining the size and shape of the

SrTiO3 polyhedral nanocrystals. The adsorption energy of alcohol molecules on

SrTiO3 {110} facet is decided by their pKa values, which are critical for

morphology control. Using the same strategy, a series of BaTiO3 polyhedral

nanocrystals with systematic morphology evolution have also been successful

prepared.

1. Introduction

Over the past decade, considerable attention has

been paid to the shape-controlled synthesis of

colloidal nanocrystals [1-6]. The physical and

chemical properties of nanocrystals are dependent on

not only their size and shape, but also their intrinsic

microstructure that is related to their synthetic route

[7]. Polyhedral nanocrystals with distinct facets thus

provides a reliable platform to examine the

facet-dependent properties due to the same synthetic

conditions. Generally, shape-controlled synthesis of

polyhedral nanocrystal is considered to be a

kinetically controlled process, in which high-energy

facets grow more quickly than low-energy facets and

eventually vanish during growth, resulting in a

crystal shape terminated by the slow-growing

low-energy facets [8]. It is of interent to find out a

surfactant that can selectively adhere to a particular

crystal facet to effectively reduce its relative surface

energy and growth rate that eventually lead to the

Nano Research

DOI (automatically inserted by the publisher)

† These authors contributed equally.

Address correspondence to wengwj@zju.edu.cn & hanweiqiang@nimte.ac.cn

Research Article

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2 Nano Res.

synthesis of nanocrystals with well-controlled shapes.

Sun et al. determined that polyvinylpyrrolidone

(PVP) can selectively stabilize the {100} facet of silver

nanocrystals which is favored for yielding silver

nanocubes [2]. Huang et al. reported the use of

facet-specific peptide sequences as regulating agents

for the predictable synthesis of platinum

nanocrystals with selectively exposed crystal surfaces

[9]. Though certain progress has been made in

identifying certain surfactants for synthesis of certain

shape-controlled nanocrystals, it is still a

trial-and-error process in identifying an appropriate

surfactant for a new material system. Besides a

general approach of identifying facet-specific has yet

to be found, theoretical studies for understanding the

relative strength of surfactant-facet interaction is

relative scarce [10].

Researchers found that some chemical functional

groups in surfactant molecules play important role in

the interaction between the surfactant and

nanocrystal facet, e.x., an interaction between thiol

functional groups and gold nanocrystals [11].

Uptodate, though some progresses have been

achieved for synthesis of shape-controlled

single-elemental and binary nanocrystals, it is still a

challenge to synthesize shape-controlled ternary

nanocrystals. In this work, we focus on identify a

chemical functional group good for synthesis of

shape-controlled cubic perovskite nanocrystals, such

as strontium titanate (SrTiO3), which is of great

interest in fields ranging from substrate for thin-film

growth [12] to water-splitting catalysis [13] and

electronic devices [14]. An early study showed that

defective cubic SrTiO3 single-crystal particles were

produced from precipitation of an aqueous gel

suspension [15]. Recently, single-crystalline SrTiO3

multipod crystals were synthesized by

self-propagating synthesis method, in which a high

temperature was needed and the uniformity of

crystal shapes was low [16]. SrTiO3 nanocrystals were

also prepared by a topochemical method by using

titania or titanate as the titanium precursors [17,18].

To the best of our knowledge, shape-controlled

synthesis of SrTiO3 nanocrystals with systematic

shape evolution has yet to be demonstrated.

Interestingly, it is found that oxygen atoms of

molecules with hydroxyl (OH) functional groups,

such as H2O (also written as HOH), CH3OH, and

CH3CH2OH, bound to Ti cation sites, a typical Lewis

acid-base interaction between alcohol molecules and

the SrTiO3 surfaces [19-21]. The relative strength of

interaction thus was naturally dependent on the

acidic or basic properties of the OH group. The

acidity of alcohols is quantified by pKa value, which

plays an important role in determining the

adsorption energy of alcohols on the surfaces of TiO2

[22,23]. Here, we demonstrate the synthesis of

shape-controlled SrTiO3 nanocrystals with systematic

shape evolution from cube to edge-truncated cube

and truncated rhombic dodecahedra by using a

series of alcohols, such as 1,2-propanediol, ethylene

glycol, 1,2,4-butanetriol, glycerol, pentaerythritol,

with varied pKa values or concentrations. Using the

same strategy, we also synthesize shape-controlled

BaTiO3 nanocrystals.

2. Results and Discussion

To synthesize SrTiO3 nanocrystals, we have

developed a novel hydrothermal synthesis method

by using a series of alcohols as the surfactants,

titanium tetrachloride (TiCl4) aqueous solution and

strontium chloride (SrCl2) as the titanium precursor

and strontium source, respectively. Representative

scanning electron microscopy (SEM) images of the

specimens synthesized with varied pKa values and

concentrations of the alcohols are shown in Figure 1

(more examples are shown in Figure S1). When the

pKa values of the alcohols are above 15, only cubic

SrTiO3 nanocrystals are obtain even increasing the

amount of corresponding alcohols (ethonal and

1,4-butanediol, respectively) from 2 to 4. 8, 10 and 20

g (Figure 1 a, b). When the pKa value of the alcohols

is between 13 and 15, the synthesis of SrTiO3

nanocrystals with systematic shape evolution upon

adjusting the concentration of the alcohols is

achieved. As shown in the SEM images, cubic,

edge-truncated cubic and truncated rhombic

dodecahedral SrTiO3 nanocrystals are predominantly

bound by {100} and {110} facets. The degree of

truncation defined as the percentage of {110} facets

(S110/S), where S and S110 are the total surface area and

surface area of {110} facets, respectively. Figure 1c

shows the degree of truncation of truncated cubic

SrTiO3 nanocrystals increases with the increasing

amount of 1,2-propanediol from 1 to 2, 4, 6, and 12 g.

Figure 1d shows shape evolution of the SrTiO3

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3 Nano Res.

nanocrystals from truncated cubic SrTiO3 to

all-edge-truncated rhombic dodecahedral upon

increasing the amount of ethylene glycol from 1 to 2,

4, 6 and 12 g. Figure 1e shows shape evolution of the

SrTiO3 nanocrystals from truncated cubic SrTiO3

through all-edge-truncated rhombic dodecahedral to

truncated rhombic dodecahedral upon increasing the

amount of pentaerythritol from 0.1 to 0.3, 0.6, 0.8 and

1.6 g. Furthermore, the degree of truncation of the

SrTiO3 nanocrystals evidently increases from 0 to 0.65,

0.84 and 0.95 with reducing the pKa value of the

alcohols, as shown in Figure 1V. In the present

system, the strength of interaction between the

alcohol molecule and {110} facet is enhanced when

alcohol with lower pKa value is introduced, which

leads to the reducing of the relative surface energy of

{110} facets and ultimately exposing more {110} facets

exposed on the crystal surface. When the

concentrations of all used alcohols are increased

excessively, nanocrystals with the smaller sizes are

obtained, as illustrated in Figure 1VI.

Figure 1. SEM images of the SrTiO3 nanocrystals synthesized

with varied pKa value and concentrations of the alcohols. a,

ethonal: I (2 g; 239 ± 28 nm), II (4 g; 243 ± 30 nm), III (8 g; 236 ± 34 nm), IV (10 g; 231 ± 32 nm), and VI (20 g; 106 ± 12 nm).

b, 1,4-butanediol: (2 g; 243 ± 36 nm), II (4 g; 236 ± 21 nm), III

(8 g; 225 ± 30 nm), IV (10 g; 234 ± 35 nm), and VI (20 g; 109 ±

18 nm). Panels a-b share one scale bar in aI: 200 nm. c,

1,2-propanediol: I (1 g; 233 ± 33 nm), II (2 g; 226 ± 26 nm), III

(4 g; 225 ± 30 nm), IV (6 g; 225 ± 32 nm), and VI (12 g; 99 ± 15

nm). d, ethylene glycol: I (1 g; 201 ± 28 nm), II (2 g; 203 ± 30

nm), III (4 g; 189 ± 25 nm), IV (6 g; 194 ± 29 nm), VI (12 g; 115 ± 16 nm). e, pentaerythritol: (0.1 g; 199 ± 19 nm), II (0.3 g; 188 ± 23 nm), III (0.6 g; 190 ± 16 nm), IV (0.8 g; 181 ± 11 nm), VI

(1.6 g; 64 ± 9 nm). Panels c-e share one scale bar in cI: 100 nm.

At least 100 particles per sample were counted to obtain the

average size.

Detailed transmission electron microscopy (TEM)

analyses are performed on the four types of the

SrTiO3 nanocrystals. The selected-area electron

diffraction (SAED) patterns are recorded from a

single-crystalline SrTiO3 nanocrystal with perfect

cubic shape (Figure 2i, inset). The incident electron

beam direction is along <100>. One kind of lattice

fringe direction attributed to (110) is observed, which

has an interplanar spacing of 0.28 nm (Figure 2m).

The inset TEM image in Figure 2j displays a typical

octagonal shape that can be identified as

edge-truncated cube bound by six {100} facets and

twelve {110} facets. The incident electron beam

direction is along <01-1>. Two kind of lattice fringe

directions attributed to (100) and (110) are observed,

which have a respective interplanar spacing of 0.39

nm and 0.28 nm (Figure 2n). Similar SAED patterns

and HRTEM images of all-edge-truncated rhombic

dodecahedra and truncated rhombic dodecahedra

viewed along the <001> and <01-1> directions are also

shown in Figure 2 (k, l) and (o, p), respectively.

Compared to edge-truncated cube,

all-edge-truncated rhombic dodecahedra and

truncated rhombic dodecahedra expose more surface

area of {110} facets and less {100} facets, as indicated

by the corresponding and HRTEM image.

Figure 2. SEM images and statistical data for the size and their

crystalline phase determination of four typical shapes of SrTiO3

nanocrystals. (a-d), SEM images of SrTiO3 cube (aIV in Fig.2,

ethonal: 10 g), truncated cube (cIV, 1,2-propanediol: 6 g),

all-edge-truncated rhombic dodecahedra (dIV, ethylene glycol: 6 g)

and truncated rhombic dodecahedra (eIV, pentaerythritol: 0.8 g),

respectively. Panels a-d share one scale bar in a: 200 nm. (e-h),

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4 Nano Res.

The corresponding size distribution of SrTiO3 nanocrystals in a-d.

(i-l), SEAD patterns recorded from the corresponding single

nanoparticle (insets) viewed along [001], [110], [001] and [110]

orientation, respectively and their corresponding high-resolution

TEM (HRTEM) images (m-p). The insets in m-p are the

corresponding Fast-Fourier-transform-filtered (FFT) patterns.

Panels m-p share one scale bar in m: 5 nm.

X-ray diffraction patterns of the SrTiO3

nanocrystals with four shapes are shown in Figure 3,

in which all the diffraction patterns match well with

those of cubic SrTiO3 phase (JCPDS No. 35-0734).

Furthermore, it is noteworthy that the ratio of the

intensity of the (220) peak to that of the (200) peak

increases from 0.30 for the cubes to 0.39, 0.46, and

0.51 for the edge-truncated cube, all-edge-truncated

rhombic dodecahedra, and truncated rhombic

dodecahedra, respectively, a trend that can be

rationally related to the increasing of the fractions of

{110} facets [24].

Figure 3. XRD patterns of different SrTiO3 nanoparticles. A

standard XRD pattern of SrTiO3 is also provided.

To gain insight into the growth mechanism of

SrTiO3 nanocrystals and the role of the alcohol

molecules played in this system, we carry out a

comparative experiment by adding the alcohols after

the complete hydrolysis of the titanium precursor. In

this case, the synthesis of SrTiO3 nanocrystals with

systematic shape evolution is still realized. And there

is virtually no difference in size distribution between

the nanocrystals produced by adding the alcohols

before/after the hydrolysis of the titanium precursor

(see Figure 4). These results might provide a clue to

support the dissolution-recrystallization mechanism.

As we know, there are two possible mechanisms for

the hydrothermal synthesis of perovskite [25]. One is

in-situ transformation from amorphous precursors

crystallize into polycrystalline particles. The other

one is dissolution-recrystallization mechanism in

which metal hydrous complex gel produces by

dissolution of the precursors followed by

recrystallization from supersaturated solution. When

the alcohol is added before the titanium precursor,

the hydrolysis of titanium precursor is retarded until

the temperature of the solution reach a certain degree

after the solution is transferred into the autoclave. In

contrast, when the alcohol is added after the titanium

precursor, the hydrolysis of titanium precursor has

been completed before the transfer of the solution

into the autoclave. These two different situations for

the hydrolysis of titanium precursor at different

temperature should affect the size distribution if this

system followed the in situ transformation

mechanism [26]. Therefore, we consider that the

hydrothermal synthesis mechanism is inclined to

dissolution-recrystallization mechanism, which is

consistent with the study by Zhang et al. [27].

Furthermore, According to the

dissolution-recrystallization mechanism for the

formation of SrTiO3 particles under hydrothermal

condition, the stability of new-formed SrTiO3 nucleus

can be enhanced by the TiO2·nH2O gel surrounding

them, which will produce smaller particle size. With

the increasing of alcohol concentration, the stability

of TiO2·nH2O gel is enhanced, as demonstrated in

Figure 4. Therefore, the particle size decreases with

the increasing of alcohol concentration.

Figure 4. (a–d) Photographs show the change in the solution

color upon increasing the amount of pentaerythritol from 0.05 to

0.1, 0.3 and 0.6 g, which suggests that the alcohol molecules can

retard hydrolysis of the titanium precursor. (e–h) Photographs

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5 Nano Res.

show no obviously change in the solution color when the

pentaerythritol is added after the complete hydrolysis of the

titanium precursor even upon increasing the amount of

pentaerythritol from 0.05 to 0.1, 0.3 and 0.6 g. (i–l) The

corresponding SEM images of the SrTiO3 nanocrystals

synthesized using solutions of (e–h). The average size: i (202 ±

21 nm), j (198 ± 19 nm), k (189 ± 26 nm), l (193 ± 30 nm).

Panels i-l share one scale bar in i: 200 nm.

On the other hand, the role of alcohols played in

hydrothermal progress has been considered as

“cosurfactant” and “cosolvent” in an aqueous system

[28]. And shape-controlled nanocrystal growth is

commonly considered to be a kinetically controlled

process [29]: surfactants that selectively adhere to a

particular crystal facet, adjusting its relative surface

energy and slow their growth. Furthermore, we

appreciate that the chemical functional groups in

molecule of surfactant contribute to the interaction

between the surfactant and crystal facet. Thus we

here assume that the relative interaction strength

(adsorption energy) between {110} facet and alcohol

molecules would be enhanced with the reduced pKa

value of alcohol molecular added, thus expose more

surface area of {110} facets on the nanocrystal surface,

as illustrated in Figure 1a–f. We carry out DFT

calculations to evaluate the relative interaction

strength (adsorption energy) between {110} facet and

three typical alcohol molecules: water, methanol, and

ethylene glycol. The results indicate that the

adsorption energy of alcohol molecule on {110} facet

is enhanced with the pKa value of alcohols reduced

(Figure 5), which is consistent with our experimental

results. The geometries are presented in Figure 5. The

interaction of water with the surface is weaker than

that of methanol, which can be attributed to the

enhancing attractive interaction between the methyl

group and the surface, a conclusion of Wang et al.

[20]. For adsorbed ethylene glycol molecule, apart

from the binding between Os-H1 and Og-Ti, the Os-H2

of 1.89 Å implies extra attractive interaction between

the two atoms. These may lead to the interaction of

ethylene glycol with the {110} facet stronger than that

of methanol and water. These DFT calculations

results suggest that the geometry and sterics of the

various alcohols used might have a great effect on the

adsorption energy between alcohols and facet [22].

Although the pKa value of alcohol, which is also

affected by the above factors, thus can be used to

reflect the combination effects of these factors on

adsorption strength, the details of the effects of the

geometry and sterics as well as carbon chains length

of the various alcohols on the adsorption energy still

need to be further uncovered.

Figure 5. Adsorption geometry and adsorption energy (Eads in eV)

of H2O (a), CH3OH (b) and HOCH2CH2OH (c) on SrTiO3 (110)

surface.

By using 1,2-propanediol as the surfactant, we

have also synthesized BaTiO3 nanocrystals with

systematic morphology evolution from cubic to

edge-truncated cubic and rhombic dodecahedral

upon increasing the concentration of 1,2-propanediol,

as shown in Figure S2. XRD patterns (Figure S3) of

the BaTiO3 nanocrystals match well to those of cubic

BaTiO3 (JCPDS No. 31-0174). The ratio of intensity of

the (220) peak to that of the (200) peak increases

gradually, which further confirms the shape

evolution process. These results indicate that alcohols

could be a general surfactants in the shape-controlled

synthesis of pervoskite titanates with systematic

morphology evolution.

3. Conclusion

We have synthsized a series of SrTiO3 nanocrystals

with systematic morphology evolution using a

variety of alcohols as the surfactants. Furthermore,

the percentage of {110} facets compared with {100}

facets in the resulting SrTiO3 nanocrystals increases

as alcohols with lower pKa value is introduced.

Using the same strategy, we have also synthesized

BaTiO3 nanocrystals with shape systematic

morphology evolution. This strategy of using alcohol

with different acidities as surfactants to shape control

the synthesis of pervoskite titanates nanocrystals

could be extended to synthesize other material

systems, which might offer great opportunities for

both fundamental research and technological

applications.

Acknowledgements

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6 Nano Res.

This work was supported by the National Basic

Research Program of China (973 project,

2012CB933600), the National Natural Science

Foundation of China (Grant No. 51072178, 51272228,

81071258 and 21273200). W.H. thanks the support

from the Project of the Ningbo 3315 International

Team.

Electronic Supplementary Material: Supplementary

material (Experimental section, Additional SEM

images of SrTiO3 nanocrystals synthesized with a

series of alcohols, shape-controlled growth of BaTiO3

nanocrystals, XRD patterns of three shapes of BaTiO3

nanocrystals, slab models of TiO-terminated SrTiO3

(110) surface) is available in the online version of this

article at http://dx.doi.org/10.1007/s12274-***-****-*. References

[1] Peng, X. G.; Manna, L.; Yang, W. D.; Wickham, J.;

Scher, E.; Kadavanich, A.; Alivisatos, A. P. Shape control of

CdSe nanocrystals. Nature 2000, 404, 59-61.

[2] Sun, Y. G.; Xia, Y. N. Shape-controlled synthesis of gold

and silver nanoparticles. Science 2002, 298, 2176-2179.

[3] Yang, H. G.; Sun, C. H.; Qiao, S. Z.; Zou, J.; Liu, G.;

Smith, S. C.; Cheng, H. M.; Lu, G. Q. Anatase TiO(2) single

crystals with a large percentage of reactive facets. Nature 2008,

453, 638-642.

[4] Tian, N.; Zhou, Z.-Y.; Sun, S.-G.; Ding, Y.; Wang, Z. L.

Synthesis of tetrahexahedral platinum nanocrystals with

high-index facets and high electro-oxidation activity. Science

2007, 316, 732-735.

[5] Habas, S. E.; Lee, H.; Radmilovic, V.; Somorjai, G. A.;

Yang, P. Shaping binary metal nanocrystals through epitaxial

seeded growth. Nat. Mater. 2007, 6, 692-697.

[6] Huang, M. H.; Lin, P.-H. Shape-controlled synthesis of

polyhedral nanocrystals and their facet-dependent properties.

Adv. Funct. Mater. 2012, 22, 14-24.

[7] Rabuffetti, F. A.; Kim, H.-S.; Enterkin, J. A.; Wang, Y.;

Lanier, C. H.; Marks, L. D.; Poeppelmeier, K. R.; Stair, P. C.

Synthesis-dependent first-order Raman scattering in SrTiO3

nanocubes at room temperature. Chem. Mater. 2008, 20,

5628-5635.

[8] Viswanath, B.; Kundu, P.; HaIder, A.; Ravishankar, N.

Mechanistic aspects of shape selection and symmetry breaking

during nanostructure growth by wet chemical methods. J. Phys.

Chem. C 2009, 113, 16866-16883.

[9] Chiu, C.-Y.; Li, Y.; Ruan, L.; Ye, X.; Murray, C. B.;

Huang, Y. Platinum nanocrystals selectively shaped using

facet-specific peptide sequences. Nat. Chem. 2011, 3, 393-399.

[10] Lee, K.; Kim, M.; Kim, H. Catalytic nanoparticles being

facet-controlled. J. Mater. Chem. 2010, 20, 3791-3798.

[11] Hakkinen, H. The gold-sulfur interface at the nanoscale.

Nat. Chem. 2012, 4, 443-455.

[12] Ohtomo, A.; Hwang, H. Y. A high-mobility electron gas

at the LaAlO3/SrTiO3 heterointerface. Nature 2004, 427,

423-426.

[13] Townsend, T. K.; Browning, N. D.; Osterloh, F. E.

Nanoscale strontium titanate photocatalysts for overall water

splitting. Acs Nano 2012, 6, 7420-7426.

[14] Cen, C.; Thiel, S.; Mannhart, J.; Levy, J. Oxide

nanoelectronics on demand. Science 2009, 323, 1026-1030.

[15] Calderone, V. R.; Testino, A.; Buscaglia, M. T.; Bassoli,

M.; Bottino, C.; Viviani, M.; Buscaglia, V.; Nanni, P. Size and

shape control of SrTiO3 particles grown by epitaxial

self-assembly. Chem. Mater. 2006, 18, 1627-1633.

[16] Toshima, T.; Ishikawa, H.; Tanda, S.; Akiyama, T.

Multipod crystals of perovskite SrTiO3. Cryst. Growth Des.

2008, 8, 2066-2069.

[17] Yang, J.; Geng, B.; Ye, Y.; Yu, X. Stick-like titania

precursor route to MTiO3 (M = Sr, Ba, and Ca) polyhedra.

Crystengcomm 2012, 14, 2959-2965.

[18] Kalyani, V.; Vasile, B. S.; Ianculescu, A.; Buscaglia, M.

T.; Buscaglia, V.; Nanni, P. Hydrothermal synthesis of SrTiO3

mesocrystals: single crystal to mesocrystal transformation

induced by topochemical reactions. Cryst. Growth Des. 2012,

12, 4450-4456.

[19] Wang, L. Q.; Ferris, K. F.; Azad, S.; Engelhard, M. H.;

Peden, C. H. F. Adsorption and reaction of acetaldehyde on

stoichiometric and defective SrTiO3(100) surfaces. J. Phys.

Chem. B 2004, 108, 1646-1652.

[20] Wang, L. Q.; Ferris, K. F.; Azad, S.; Engelhard, M. H.

Adsorption and reaction of methanol on stoichiometric and

defective SrTiO3(100) surfaces. J. Phys. Chem. B 2005, 109,

4507-4513.

[21] Becerra-Toledo, A. E.; Castell, M. R.; Marks, L. D.

Water adsorption on SrTiO3(001): I. Experimental and

simulated STM. Surf. Sci. 2012, 606, 762-765.

[22] Bates, S. P.; Kresse, G.; Gillan, M. J. The adsorption and

dissociation of ROH molecules on TiO2(110). Surf. Sci. 1998,

409, 336-349.

[23] Kieu, L.; Boyd, P.; Idriss, H. Trends within the

adsorption energy of alcohols over rutile TiO2(110) and (011)

clusters. J. Mol. Catal. a-Chem. 2002, 188, 153-161.

[24] Huang, W.-C.; Lyu, L.-M.; Yang, Y.-C.; Huang, M. H.

Synthesis of Cu2O nanocrystals from cubic to rhombic

dodecahedral structures and their comparative photocatalytic

activity. J. Am. Chem. Soc. 2012, 134, 1261-1267.

[25] Moon, J.; Kerchner, J.A.; Krarup, H.; Adair, J.H.

Hydrothermal synthesis of ferroelectric perovskites from

chemically modified titanium isopropoxide and acetate salts. J.

Mater. Res. 1999, 14 , 425-435.

[26] Zhang, S.C.; Han, Y.X.; Chen, B.C.; Song, X.P. The

influence of TiO2 center dot H2O gel on hydrothermal synthesis

of SrTiO3 powders. Mater. Lett. 2001, 54, 368-370.

www.theNanoResearch.com∣www.Springer.com/journal/12274 | Nano Research

7 Nano Res.

[27] Zhang, S.C.;Liu J.X.; Han, Y.X.; Chen, B.C.; Li, X.G.

Formation mechanisms of SrTiO3 nanoparticles under

hydrothermal conditions. Mater. Sci. Eng., B, 2004, 110, 11-17.

[28] Zana, R. Aqueous surfactant-alcohol systems: A review.

Adv. Colloid Interface Sci. 1995, 57,1-64.

[29] Yin, Y.; Alivisatos, A.P. Colloidal nanocrystal synthesis

and the organic-inorganic interface. Nature, 2005, 437,

664-670.

www.theNanoResearch.com∣www.Springer.com/journal/12274 | Nano Research

Nano Res.

Electronic Supplementary Material

Shape-Controlled Growth of SrTiO3 Ployhedral

Nanocrystals

Lingqing Dong1,2,†

, Hui Shi3,†

, Kui Cheng1,†

, Qi Wang3, Wenjian Weng

1,4() and Wei-Qiang Han

2()

1 Department of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Cyrus Tang

Center for Sensor Materials and Applications, Zhejiang University, Hangzhou 310027, China.

2 Ningbo Institute of Materials Technology & Engineering, Chinese Academy of Sciences, Ningbo 315210,

China.

3 Soft Matter Research Center and Department of Chemistry, Zhejiang University, Hangzhou 310027,

China. 4 Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China.

Supporting information to DOI 10.1007/s12274-****-****-* (automatically inserted by the publisher)

Experimental Section

Synthesis of SrTiO3 and BaTiO3 Nanocrystals: In a typical synthesis, 0.265 ml of TiCl4 (aladdin, 99%) was

dropwised into 25ml of deionized water containing different amount of the corresponding alcohol cooled in an

ice bath. After stirring for 5 min, 30 ml of 3M LiOH (aladdin, 98%) solution and 10 ml of 0.24M SrCl2/BaCl2

(aladdin, 99.5%) solution were orderly added. The pH of the solution is approximately 13.5. After stirred for

another 30 min, the resulting solution was transferred to a homemade 50 ml Teflon-lined stainless steel

autoclave. Subsequently, the autoclave was heated for 48 h at 180 oC. After the reaction, the resulting precipitate

was centrifuged off, washed with water and ethanol alternately 5 times each, then dried at 70 oC for 12 h.

DFT Calculations of Adsorption Energy of Alcohol Molecules on {110} Facet: Density Functional Theory (DFT)

calculations were implemented using projector-augmented wave (PAW) potential [30] and generalized gradient

approximation (GGA), in the form of Perdew-Burke-Ernzerhof functional [31] using the Vienna ab initio

simulation package (VASP) [32,33]. Unit cell optimization gave parameters of a=b=c=3.912 Å , in good

agreement with experimental value of 3.905 Å by Becerra-Toledo et al.[34] The SrTiO3 (110) surface was

modeled with slabs cut from the crystal. Five-layer slabs of 3×3 surface unit cell with a vacuum of 20 Å were

chosen. The reconstructed TiO-terminated (110) surface was considered in this work (Figure S4).[35] The

plane-wave cutoff was set as 400 eV. Γ point was used. The centre layer was fixed and the other four layers were

allowed to relax until the force acting on each was less than 0.05 eV/Å . The interactions of molecules with the

surfaces were studied, in the form of adsorption energy (Eads). Eads is defined as Eads=Emolecule-surface -

(Esurface+Emolecule), where Emolecule-surface is the total energy of the surface with molecule, Esurface is the total energy of

the clean surface, and Emolecule is the energy of molecule.

Characterizations: Size, morphology and microstructure of the nanocrystals was measured by a field-emission

scanning electron microscopy (FESEM, HITACHI SU70) and a transmission electron microscopy (TEM, FEI

JEM-2100). The crystal structure of the specimens was studied by X-ray power diffraction microdiffractometer

(XRD Bruker-AXS-D5005) operating with Cu Kα radiation (λ= 1.5406 Å ).

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Nano Res.

Figure S1. SEM images of the SrTiO3 nanocrystals synthesized with varied pKa value and concentrations of

the alcohols. When the pKa value of the alcohols were above 15 (a, 1,5-pentanediol; b, methanol), cubes were

synthesized even with the increasing addition of the corresponding alcohols from 2 to 4, 8 and 10 g. Panels

a-b share one scale bar in aI: 100 nm. c, the degree of truncation of truncated cubic SrTiO3 nanocrystals

increased with the increasing amount of 1,2,4-butanetriol from 1 to 2, 4 and 6 g. d, shape evolution of the

SrTiO3 nanocrystals from truncated cubic SrTiO3 to all-edge-truncated rhombic dodecahedra upon increasing

the amount of glycerol from 1 to 2, 4 and 6 g. Panels c-d share one scale bar in cI: 200 nm.

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Nano Res.

Figure S2. SEM images (a-c) of the BaTiO3 nanocrystals synthesized with 20 g KOH for 0.265 ml TiCl4 and

equal amount of BaCl2·6H2O (in mole ratio) at 180 oC for 20 h; the morphology evolution from cubic to

truncated cubic and rhombic dodecahedra upon increasing the amount of surfactant 1,2-propanediol from

(a) 0 to (b) 2 ml and (c) 4 ml. Panels a-c share one scale bar in a: 100 nm.

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Nano Res.

Figure S3. XRD patterns of the three BaTiO3 nanocrystals in Figure S2, which is good agreement with cubic

BaTiO3 (JCPDS No. 31-0174); the ratio of the intensity of the (220) peak to that of the (200) peak increases

from 0.43 to 0.56 and 0.63. A standard XRD pattern of BaTiO3 is also provided.

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Nano Res.

Figure S4. Slab models of TiO-terminated SrTiO3 (110) surface.

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Nano Res.

References

[30] Kresse, G.; Joubert, D. From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B 1999, 59,

1758-1775.

[31] Perdew, J. P.; Burke, K.; Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. L 1996, 77, 3865-3868.

[32] Kresse, G.; Hafner, Ab. initio molecular dynamics for liquid metals. J. Phys. Rev. B. 1993, 47, 558-561.

[33] Kresse, G.; Furthmuller, Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. J. Phys.

Rev. B. 1996, 54, 11169-11186.

[34] Becerra-Toledo, A. E.; Enterkin, J. A.; Kienzle, D. M.; Marks, L. D. Water adsorption on SrTiO3(001): II. Water, water,

everywhere. Surf. Sci. 2012, 606, 791-802.

[35] Biswas, A.; Rossen, P. B.; Yang, C. H.; Siemons, W.; Jung, M. H.; Yang, I. K.; Ramesh, R.; Jeong, Y. H. Universal Ti-rich

termination of atomically flat SrTiO3 (001), (110), and (111) surfaces. Appl. Phys. Lett. 2011, 98, 051904.

† These authors contributed equally.

Address correspondence to wengwj@zju.edu.cn & hanweiqiang@nimte.ac.cn