German Edition: DOI: 10.1002/ange.2017038712D NanosheetsInternational Edition: DOI: 10.1002/anie.201703871

A Generalized Strategy for the Synthesis of Large-Size Ultrathin Two-Dimensional Metal Oxide NanosheetsHewei Zhao, Yujie Zhu, Fengshi Li, Rui Hao, Shaoxiong Wang, and Lin Guo*

Abstract: Two-dimensional (2D) nanomaterials show uniqueelectrical, mechanical, and catalytic performance owing to theirultrahigh surface-to-volume ratio and quantum confinementeffects. However, ways to simply synthesize 2D metal oxidenanosheets through a general and facile method is still a bigchallenge. Herein, we report a generalized and facile strategy tosynthesize large-size ultrathin 2D metal oxide nanosheets byusing graphene oxide (GO) as a template in a wet-chemicalsystem. Notably, the novel strategy mainly relies on accuratelycontrolling the balance between heterogeneous growth andnucleation of metal oxides on the surface of GO, which isindependent on the individual character of the metal elements.Therefore, ultrathin nanosheets of various metal oxides,including those from both main-group and transition elements,can be synthesized with large size. The ultrathin 2D metaloxide nanosheets also show controllable thickness and uniquesurface chemical state.

Two-dimensional (2D) nanomaterials, that is, nanosheets,have intensively attracted a great deal of interest owing totheir widescale applications, including mechanical improve-ment, energy storage and conversion, catalysis (photo/elec-tro-), and sensors.[1] Some 2D nanomaterials, such as gra-phene, metal oxides, metal chalcogenides, metal carbides, andblack phosphorus have been successfully synthesized duringthe past decades.[2] Exfoliation is a typical and efficient “top-down” method to synthesize 2D nanomaterials,[2e,3] such asMoS2, montmorillonite (MTM), and black phosphorus, butthis method is limited to materials which have a layeredstructure in their original bulk crystals, and has difficulty infabricating large-size 2D nanomaterials. Alternatively, chem-ical vapor deposition (CVD) is a common “bottom-up”method to fabricate 2D nanomaterials, especially for materi-als without an original layered structure, such as WS2, SnS2,and boron.[4] During CVD processes, atoms, ions, or mole-cules can directly grow into 2D nanomaterials. However,CVD is energy-intensive, time-consuming, and very compli-cated, which extremely restrict its applications.[1h] Templatedmethod has also been used to synthesize non-layered 2Dnanomaterials, such as Au and Au@Ag, but the size of which

is typically confined to 500 nm.[5] Recently, solvo-/hydro-thermal methods hasve also been reported to synthesize 2Dnanomaterials, but these are only applicable to transition-metal oxides.[2b, 6] So far, it is challenging to synthesize large-size 2D nanomaterials under facile conditions, especially formetal oxides from both main-group and transition-metalelements, which do not possess an original layered structure.

Herein, we develop a general strategy for the synthesis oflarge-size 2D metal oxide (MO) nanosheets with thickness ofseveral nanometers (several atoms) by using graphene oxide(GO) as a template under wet-chemical conditions. Thisstrategy mainly involves the uniform growth of MO on thesurface of GO to form nanosheets, instead of independent andpolydispersed particles. Designed on the basis of thermody-namic and kinetic principles, our method is able to accuratelycontrol the diffusion direction, speed of adsorption, formationof nuclei, and rate of hydrolysis, the synergistic effect of whichresults in the formation of ultrathin nanosheets. As ourstrategy is based on the balance between heterogeneousgrowth and nucleation of metal ions, independent of theindividual character of the element, it can be generalized tofabricate nanosheets of various materials. Although here wetake MgO, ZrO2, Al2O3, TiO2, SnO2, and Sb2O5 as examples tointroduce the strategy, it is believed that this unique strategy isgeneral in the sense that ultrathin 2D nanosheets of a largevariety of MOs may be synthesized, so that the potentialapplications of 2D nanomaterials will be greatly broadened,including coatings, aerospace, and infrastructure.

Scheme 1 illustrates the principle of our method. First,metal ions and GO are evenly dispersed in the solution under

Scheme 1. The strategy for synthesis of large-size ultrathin 2D MOnanosheets.

[*] Dr. H. Zhao, Prof. Y. Zhu, Dr. F. Li, Dr. R. Hao, Dr. S. Wang,Prof. L. GuoSchool of Chemistry, Key Laboratory of Bio-Inspired Smart InterfacialScience and Technology, Ministry of Education, Beijing AdvancedInnovation Center for Biomedical Engineering, Beihang UniversityBeijing, 100191 (China)E-mail: guolin@buaa.edu.cn

Supporting information and the ORCID identification number(s) forthe author(s) of this article can be found under:https://doi.org/10.1002/anie.201703871.

AngewandteChemieCommunications

8766 T 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Angew. Chem. Int. Ed. 2017, 56, 8766 –8770

strong agitation. On the surface of GO, numerous singleelectrons of carbon atoms form the large conjugated pibonds,[1a] which cause the surface of GO to be negativelycharged. Owing to electrostatic attraction, the positivelycharged metal ions are attracted by GO and finally attach onits surface (Scheme 1). It is critical to minimize the hydrolysisof metal ions before they are adsorbed on the surface of GO.Here, it is realized by controlling the pH of the solution sothat the hydrolysis reaction is significantly mitigated. Besides,under room temperature (20–25 88C), the hydrolysis rate isexpected to be extremely slow.[7] Moreover, considering thequick adsorption process induced by the electrostatic attrac-tion,[8] it is anticipated that under room temperature, byappropriate manipulation of pH, hydrolysis of metal ions canbe kept to a very low extent during the adsorption process(Scheme 1). Second, after the completion of the adsorptionprocess, the hydrolysis is accelerated by increasing the systemtemperature[7] (to 60–70 88C), which will result in nucleationand growth of MO precursor on the surface of GO to form anultrathin MO precursor coating (GO@MO precursor;Scheme 1). To avoid the formation of independent largeprecipitates of MO precursor, the speed of hydrolysis iscontrolled by adjusting the pH, concentration of metal ions,selection of solvent (deionized water or ethylene glycol-deionized water mixture) and temperature (see the Methodssection in the Supporting Information for details), so that MOprecursor is slightly supersaturated in the solution to achievea balance between nucleation and growth of MO precursor.Finally, the GO@MO precursor composites are thermallytreated (650 88C for 2 h), during which GO is removed and theultrathin 2D MO nanosheets can be obtained (Scheme 1). Asthe synthetic procedure mainly relies on the initially con-trolled hydrolysis of metal ions and the balance betweennucleation and growth of MO precursor on the GO surfaceinstead of the intrinsic nature of metal ions, it is able tosynthesize ultrathin 2D nanosheets of a myriad of MOsincluding both main-group and transition-metal regions.Besides, as the lateral size of the ultrathin 2D MO nanosheetsis determined by that of GO, which can be easily produced upto dozens of micrometers, this approach is also a feasible wayto synthesize large-size MO nanosheets.

By adopting the method, we have successfully synthesizedultrathin 2D nanosheets for six different MOs, namely MgO,ZrO2, Al2O3, TiO2, SnO2, and Sb2O5, all of which do notpossess original layered structures. The morphology of theultrathin 2D MO nanosheets is characterized by scanningelectron microscopy (SEM) and transmission electron mi-croscopy (TEM), shown in Figure 1. The ultrathin 2D nano-sheets morphology for all the six MOs can be easilyrecognized from the low magnification SEM (Fig-ure 1a,d,g,j,m,p) and TEM images (Figure 1b,e,h,k,n,q). Thewrinkled edges of the nanosheets are due to surface tension,which have been frequently observed in GO.[9] The size of thenanosheets can be tuned up to 50 mm, which is determined bythe size of the sacrificial GO templates (Figure 1). The Al2O3

nanosheets are amorphous, while MgO, ZrO2, TiO2, SnO2,and Sb2O5 nanosheets show crystalline phases, which areidentified as periclase, tetragonal, anatase, cassiterite, andcervantite, respectively, by the corresponding X-ray diffrac-

tion (XRD) patterns (Supporting Information, Figure S1) andhigh-resolution TEM (HRTEM) images (Figure 1c,f,i,l,o,r).We believe that the ultrahigh thermal stability of alumina isresponsible for its amorphous state,[1c,10] while other MOnanosheets will crystallize during thermal treatment. Exceptthe amorphous Al2O3, the exposed facets of other ultrathin2D MO nanosheets are obtained by analyzing the latticeimages (insets in Figure 1c,f,l,o,r), which are (001), (001),(010), (001), and (010) for MgO, ZrO2, TiO2, SnO2, and Sb2O5,respectively. The exposed facets can play a significant role indetermining the chemical activity of 2D nanosheets, forexample it has been demonstrated that the exposed (010)high-energy facets can greatly promote the chemical activityof TiO2.

[6] To investigate the formation mechanisms of MOnanosheets, SEM and TEM are also conducted to character-ize the morphology of the intermediate product GO@MOprecursor, which is almost identical to that of GO for all sixMOs (Supporting Information, Figures S2, S3). The surface ofGO@MO precursor is smooth without any individual par-ticles on it. The EDS elemental mapping (SupportingInformation, Figure S2) results confirm that the correspond-ing metal elements are evenly distributed on the whole

Figure 1. Morphology of ultrathin 2D MO nanosheets. SEM images(a,d,g,j,m,p), low-magnification (b,e,h,k,n,q) and high-resolution TEMimages (c,f,i,l,o,r) of ultrathin 2D nanosheets for MgO (a–c), ZrO2 (d–f), Al2O3 (g–i), TiO2 (j–l), SnO2 (m–o), and Sb2O5 (p–r). HRTEM detailsof the six MOs are shown as the insets in c, f, i, l, o, and r,respectively; scale bars: 1 nm.

AngewandteChemieCommunications

8767Angew. Chem. Int. Ed. 2017, 56, 8766 –8770 T 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.angewandte.org

surface, demonstrating the uniform coating of MO precursoron the surface of GO.

Atomic force microscopy (AFM) was conducted todetermine the thickness of the MO nanosheets. As shown inthe Supporting Information, Figure S4, the thickness rangesfrom 2.1 nm to 4.7 nm, equivalent to few monomolecularlayers (Supporting Information, Table S1). Taking MgOnanosheet as an example, its thickness is around 3.6 nm(Supporting Information, Figure S4), suggesting that thenanosheet consists of 8 stacking monolayer (thickness ofmonolayer MgO is about 0.45 nm[11]). In general, all of theMO nanosheets synthesized herein are thin enough to presentquantum confinement effects, indicating their potentialapplications in some novel electronic devices.[6] Besides,thickness of the ultrathin 2D MO nanosheets can becontrolled by changing the concentration of the metal saltsin the solutions (Supporting Information, Figure S5). AFM isalso conducted on the GO@MO precursor before thermaltreatment, the thickness of which ranges from 2.7 nm to5.9 nm (Supporting Information, Figure S6). The thicknessdecrease from GO@MO precursor to MO nanosheets ismainly caused by the removal of GO and crystallization ofMO after the thermal treatment.

The key of our strategy is the balance between heteroge-neous growth and nucleation of metal ions during hydrolysis,which is greatly affected by the pH of the system, as indicatedby the LaMerQs law.[12] To achieve the balance, buffersolution,[13] which can accurately control pH during thereaction process, is used herein.

A series of experiments and calculations are performed todemonstrate the effect of pH on the formation of MOnanosheets, and the results are displayed in Figure 2. Toprecipitate MO precursor (M(OH)n) in the solution, itssaturation point has to be reached. Therefore, the ionicproduct of MO precursor (Kmp) needs to be higher than thesolubility constant (Ksp) of metal hydroxide. Thus, a minimumpH value is required, which can be calculated based on theequivalence between Kmp and Ksp, as shown in Figure 2. Asthe pH value increases to reach certain threshold, fasthydrolysis will result in continual and massive production ofnuclei, leading to non-uniform growth of MO. As a result, thefinal product will contain independent and polydispersed

particles instead of nanosheets. This maximum pH value isexperimentally determined and also shown in Figure 2. Onlywhen the pH is in the range between the maximum andminimum values, the ultrathin 2D MO nanosheets can beformed (Figure 2). Taking MgO as an example, a pH valuebetween 9.6 and 10.6 can generate the ultrathin MgOnanosheet (Figure 2). Under a pH value of 8.3, the filmmorphology of the intermediate product can be observedfrom the SEM image (Supporting Information, Figure S7a),but no Mg signal is detected in the EDS spectrum (insertimage in the Supporting Information, Figure S7a), indicatingthe absence of MgO. However, when pH is too high, such as11.0, the surface of the intermediate product is rough andindependent particles are formed on the surface of GO(Figure S7b). A pH range between 9.6 and 10.6 should bemaintained to achieve slow nucleation and uniform growth ofMgO precursor on the GO so that the final 2D MgOnanosheets can be produced (morphology of GO@MgOprecursor produced under a pH value of 10.3 can be seen inthe Supporting Information, Figure S2). The pH influences onthe formation of other MO nanosheets are also studied. Thesuitable pH ranges for the formation of ZrO2, Al2O3, TiO2,SnO2, and Sb2O5 nanosheets are determined to be 3.6–8, 3.8–4.6, 2–3.2, 1.5–2.5, and 1.7–2.7, respectively (Figure 2), and theeffect of pH on the morphology and composition of theintermediate products is shown in the Supporting Informa-tion, Figure S7. In particular, Ksp of TiO2, SnO2, and Sb2O5 istoo low (lower than 10@65), which means they are extremelyeasy to hydrolyze even at very low pH (Figure 2). Ethyleneglycol (EG) is introduced into the reaction system as a diluentto further slow the speed of hydrolysis (Supporting Informa-tion, Table S2).

One typical character of the 2D nanosheets is theultrahigh percentage of surface,[6] which may generateunique properties for the 2D nanosheets. It has been reportedthat the atoms exposed on the surface exhibit differentchemical states compared with the inner atoms.[11, 14] Thesurface chemical states of the six MO nanosheets were testedby X-ray photoelectron spectroscopy (XPS). The bindingenergy for all metal elements shows a 0.1–0.8 eV shift to lowervalues compared with that of the corresponding elements inthe bulk counterparts[11, 15] (Figure 3; Supporting Information,Table S3). The lower binding energy means that the metalelements on surface of 2D nanosheets show a reduction(electron gain) state. The reduction state of metal elementswas traditionally considered as a result of electrons transferfrom oxygen to metal to make it electron gain.[6] However, thebinding energy of the core level of oxygen for all the six 2DMO nanosheets also shows a 0.1–1.8 eV shift to lower values(Figure 3; Supporting Information, Table S3), which alsomeans oxygen exhibits a reduction (electron gain) stateinstead of oxidization (electron given). Therefore, electrontransfer from oxygen to metals is not the primary reason forthe unique chemical state of the 2D nanosheets. Here, latticedistortion (Supporting Information, Figure S8) and extrachemical bond formation (Supporting Information, Fig-ure S9), which have been demonstrated as effective ways toredistribute the electron density,[14,16] also occur in the surfaceatoms of our ultrathin 2D MO nanosheets. The latticeFigure 2. Effect of pH on the formation of MO nanosheets.

AngewandteChemieCommunications

8768 www.angewandte.org T 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Angew. Chem. Int. Ed. 2017, 56, 8766 –8770

distortion and formation of new chemical bonds may shortenthe interatomic distance and make electron easier to slop overfor both metals and oxygen elements so that the bindingenergy shifts to lower values. It is certain that the unique

chemical state in the ultrathin 2D nanosheets will inducesome salient properties, which are beneficial for applicationssuch as energy storages,[17] photoelectric converting[6] andcatalysis.[18]

The chemical state of GO@MO precursor was also testedby XPS (Supporting Information, Figure S10). Electrostaticattraction is important for metal ions adsorbed on the surfaceof GO, which is the foundation of our strategy. The bindingenergy of C 1s in GO@MO precursor shows a 0.1–0.4 eV shiftto higher values for all samples comparing with that in thepristine GO (Supporting Information, Table S4), whichmeans carbon shows an oxidization (electron given) stateafter MO precursors grow on the GO. We believe that theelectrons transfer from C to metal element results in the shiftof the binding energy, which indicates the strong interactionbetween MO precursor and GO and demonstrates theimportance of electrostatic attraction (Raman and FTIRspectrum of GO@MO precursor in the Supporting Informa-tion, Figure S11 can also demonstrate the strong interactionbetween MO precursor and GO). The strong interaction canin turn facilitate the growth of MO precursor on the surface ofGO instead of separate precipitation during the hydrolysisprocess.

In summary, we have developed a universal approach tosynthesize large-size ultrathin 2D metal oxide nanosheets.The key step of this approach involves uniform coating ofmetal oxide onto surface of GO in a wet-chemical condition.This approach is exemplified by fabricating the 2D ultrathinnanosheets of six MOs, none of which possesses an originallayered structure in their bulk crystals. The success of thismethod relies on the controlled balance between nucleationand growth of metal oxide on the surface of GO, which isrealized by appropriately manipulating the pH of the systemswith stable buffer solutions. As this method is independent onthe intrinsic properties of metal ions, it is expected thata variety of metal oxides nanosheets including both main-group and transition-metal elements can be synthesized byadopting this method. We hope this synthetic procedure willfacilitate the fabrication of 2D nanomaterials; for instance,some complex compounds could be prepared through furthermodifying current method, so that the potential applicationsof 2D nanomaterials can be explored in more areas.

Acknowledgements

This work was supported by the National Natural ScienceFoundation of China (51532001), the National Basic ResearchProgram of China (2014CB931802), and the 111 Project(B14009).

Conflict of interest

The authors declare no conflict of interest.

Keywords: 2D nanosheets · graphene oxide · metal oxides ·solution-phase synthesis · thickness control

Figure 3. Surface chemical states of the ultrathin 2D MO nanosheets.XPS was conducted on MO nanosheets to test the core-level state ofmetal 1s/2p/3d and O 1s regions. High-resolution XPS spectra ofMgO (a,b), ZrO2 (c,d), Al2O3 (e,f), TiO2 (g,h), SnO2 (i,j), and Sb2O5

(k,l) show a shift to lower binding energy for both metal and oxygenelements, owing to the unique ultrathin 2D nanosheets structure.

AngewandteChemieCommunications

8769Angew. Chem. Int. Ed. 2017, 56, 8766 –8770 T 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.angewandte.org

How to cite: Angew. Chem. Int. Ed. 2017, 56, 8766–8770Angew. Chem. 2017, 129, 8892–8896

[1] a) K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, Y.Zhang, S. V. Dubonos, I. V. Grigorieva, A. A. Firsov, Science2004, 306, 666 – 669; b) C. Lee, X. Wei, J. W. Kysar, J. Hone,Science 2008, 321, 385 – 388; c) H. Zhao, Y. Yue, Y. Zhang, L. Li,L. Guo, Adv. Mater. 2016, 28, 2037 – 2042; d) H. Yin, Z. Tang,Chem. Soc. Rev. 2016, 45, 4873 – 4891; e) F. Bonaccorso, L.Colombo, G. Yu, M. Stoller, V. Tozzini, A. C. Ferrari, R. S.Ruoff, V. Pellegrini, Science 2015, 347, 1246501; f) Q. Fu, X. Bao,Chem. Soc. Rev. 2016, 46, 1842 – 1874; g) C. Zhu, Z. Zeng, H. Li,F. Li, C. Fan, H. Zhang, J. Am. Chem. Soc. 2013, 135, 5998 – 6001;h) C. Tan, H. Zhang, Nat. Commun. 2015, 6, 7873; i) X. Zhang,Z. Lai, C. Tan, H. Zhang, Angew. Chem. Int. Ed. 2016, 55, 8816 –8838; Angew. Chem. 2016, 128, 8960 – 8984; j) Q. Lu, Y. Yu, Q.Ma, B. Chen, H. Zhang, Adv. Mater. 2016, 28, 1917 – 1933.

[2] a) T. Wu, X. Zhang, Q. Yuan, J. Xue, G. Lu, Z. Liu, H. Wang, H.Wang, F. Ding, Q. Yu, X. Xie, M. Jiang, Nat. Mater. 2016, 15, 43 –47; b) Y. Sun, Q. Liu, S. Gao, H. Cheng, F. Lei, Z. Sun, Y. Jiang,H. Su, S. Wei, Y. Xie, Nat. Commun. 2013, 4, 2899; c) X. Yin, Z.Ye, D. A. Chenet, Y. Ye, K. OQBrien, J. C. Hone, X. Zhang,Science 2014, 344, 488 – 490; d) M. Naguib, O. Mashtalir, J. Carle,V. Presser, J. Lu, L. Hultman, Y. Gogotsi, M. W. Barsoum, ACSNano 2012, 6, 1322 – 1331; e) L. Li, Y. Yu, G. J. Ye, Q. Ge, X. Ou,H. Wu, D. Feng, X. H. Chen, Y. Zhang, Nat. Nanotechnol. 2014,9, 372 – 377; f) C. Tan, X. Cao, X. J. Wu, Q. He, J. Yang, X.Zhang, J. Chen, W. Zhao, S. Han, G.-H. Nam, M. Sindoro, H.Zhang, Chem. Rev. 2017, 117, 6225 – 6331; g) H. Zhang, AcsNano 2015, 9, 9451 – 9469; h) C. Tan, H. Zhang, Chem. Soc. Rev.2015, 44, 2713 – 2731.

[3] a) B. Radisavljevic, A. Kis, Nat. Mater. 2013, 12, 815 – 820; b) J.Zhu, X. Liu, M. L. Geier, J. J. McMorrow, D. Jariwala, M. E.Beck, W. Huang, T. J. Marks, M. C. Hersam, Adv. Mater. 2016,28, 63 – 68; c) C. Tan, P. Yu, Y. Hu, J. Chen, Y. Huang, Y. Cai, Z.Luo, B. Li, Q. Lu, L. Wang, Z. Liu, H. Zhang, J. Am. Chem. Soc.2015, 137, 10430 – 10436; d) Z. Zeng, Z. Yin, X. Huang, H. Li, Q.He, G. Lu, F. Boey, H. Zhang, Angew. Chem. Int. Ed. 2011, 50,11093 – 11097; Angew. Chem. 2011, 123, 11289 – 11293.

[4] a) Q. Ji, Y. Zhang, Y. Zhang, Z. Liu, Chem. Soc. Rev. 2015, 44,2587 – 2602; b) Y. Zhang, Y. Zhang, Q. Ji, J. Ju, H. Yuan, J. Shi, T.Gao, D. Ma, M. Liu, Y. Chen, X. Song, H. Y. Hwang, Y. Cui, Z.Liu, ACS Nano 2013, 7, 8963 – 8971; c) X. Zhou, Q. Zhang, L.Gan, H. Li, T. Zhai, Adv. Funct. Mater. 2016, 26, 4405 – 4413;d) G. Tai, T. Hu, Y. Zhou, X. Wang, J. Kong, T. Zeng, Y. You, Q.Wang, Angew. Chem. Int. Ed. 2015, 54, 15473 – 15477; Angew.Chem. 2015, 127, 15693 – 15697.

[5] a) X. Huang, S. Li, Y. Huang, S. Wu, X. Zhou, S. Li, C. L. Gan, F.Boey, C. A. Mirkin, H. Zhang, Nat. Commun. 2011, 2, 292; b) Z.

Fan, X. Huang, Y. Han, M. Bosman, Q. Wang, Y. Zhu, Q. Liu, B.Li, Z. Zeng, J. Wu, W. Shi, S. Li, C. L. Gan, H. Zhang, Nat.Commun. 2015, 6, 6571; c) Z. Fan, H. Zhang, Chem. Soc. Rev.2016, 45, 63 – 82; d) Z. Fan, Y. Zhu, X. Huang, Y. Han, Q. Wang,Q. Liu, Y. Huang, C. L. Gan, H. Zhang, Angew. Chem. Int. Ed.2015, 54, 5672 – 5676; Angew. Chem. 2015, 127, 5764 – 5768.

[6] Z. Sun, T. Liao, Y. Dou, S. M. Hwang, M.-S. Park, L. Jiang, J. H.Kim, S. X. Dou, Nat. Commun. 2014, 5, 3813.

[7] G. E. Boyd, A. W. Adamson, L. S. Myers, Jr., J. Am. Chem. Soc.1947, 69, 2836 – 2848.

[8] X. Zhou, Y.-X. Yin, L.-J. Wan, Y.-G. Guo, Adv. Energy Mater.2012, 2, 1086 – 1090.

[9] M. J. Allen, V. C. Tung, R. B. Kaner, Chem. Rev. 2010, 110, 132 –145.

[10] M. Kuemmel, D. Grosso, U. Boissiere, B. Smarsly, T. Brezesinski,P. A. Albouy, H. Amenitsch, C. Sanchez, Angew. Chem. Int. Ed.2005, 44, 4589 – 4592; Angew. Chem. 2005, 117, 4665 – 4668.

[11] J. Pal, M. Smerieri, E. Celasco, L. Savio, L. Vattuone, M. Rocca,Phys. Rev. Lett. 2014, 112, 126102.

[12] V. K. LaMer, R. H. Dinegar, J. Am. Chem. Soc. 1950, 72, 4847 –4854.

[13] X. F. Guo, X. H. Qian, L. H. Jia, J. Am. Chem. Soc. 2004, 126,2272 – 2273.

[14] H. Wang, J. Zhang, X. Hang, X. Zhang, J. Xie, B. Pan, Y. Xie,Angew. Chem. Int. Ed. 2015, 54, 1195 – 1199; Angew. Chem.2015, 127, 1211 – 1215.

[15] a) G. Freiman, P. Barboux, J. PerriHre, K. Giannakopoulos, ThinSolid Films 2009, 517, 2670 – 2674; b) H. Y. Yu, M. F. Li, B. J.Cho, C. C. Yeo, M. S. Joo, D. L. Kwong, J. S. Pan, C. H. Ang, J. Z.Zheng, S. Ramanathan, Appl. Phys. Lett. 2002, 81, 376 – 378;c) B. Erdem, R. A. Hunsicker, G. W. Simmons, E. D. Sudol, V. L.Dimonie, M. S. El-Aasser, Langmuir 2001, 17, 2664 – 2669;d) M. T. Uddin, Y. Nicolas, C. Olivier, T. Toupance, L. Servant,M. M. Mueller, H.-J. Kleebe, J. Ziegler, W. Jaegermann, Inorg.Chem. 2012, 51, 7764 – 7773; e) R. G. Haverkamp, A. T. Mar-shall, B. C. C. Cowie, Surf. Interface Anal. 2011, 43, 847 – 855.

[16] Z. Lin, A. Yin, J. Mao, Y. Xia, N. Kempf, Q. He, Y. Wang, C.-Y.Chen, Y. Zhang, V. Ozolins, Z. Ren, Y. Huang, X. Duan, Sci.Adv. 2016, 2, e1600993.

[17] X. Huang, Z. Zeng, H. Zhang, Chem. Soc. Rev. 2013, 42, 1934 –1946.

[18] M. Kitano, Y. Inoue, Y. Yamazaki, F. Hayashi, S. Kanbara, S.Matsuishi, T. Yokoyama, S.-W. Kim, M. Hara, H. Hosono, Nat.Chem. 2012, 4, 934 – 940.

Manuscript received: April 19, 2017Accepted manuscript online: June 1, 2017Version of record online: June 19, 2017

AngewandteChemieCommunications

8770 www.angewandte.org T 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Angew. Chem. Int. Ed. 2017, 56, 8766 –8770

本文献由“学霸图书馆-文献云下载”收集自网络，仅供学习交流使用。

学霸图书馆（www.xuebalib.com）是一个“整合众多图书馆数据库资源，

提供一站式文献检索和下载服务”的24 小时在线不限IP

图书馆。

图书馆致力于便利、促进学习与科研，提供最强文献下载服务。

图书馆导航：

图书馆首页 文献云下载 图书馆入口 外文数据库大全 疑难文献辅助工具