German Edition: DOI: 10.1002/ange.201603223 Nanostructures International Edition: DOI: 10.1002/anie.201603223 Self-Construction from 2D to 3D: One-Pot Layer-by-Layer Assembly of Graphene Oxide Sheets Held Together by Coordination Polymers MohamedB. Zakaria, Cuiling Li, Qingmin Ji, Bo Jiang, Satoshi Tominaka, Yusuke Ide, JonathanP. Hill, Katsuhiko Ariga,* and Yusuke Yamauchi* Abstract: Deposition of Ni-based cyanide bridged coordina- tion polymer (NiCNNi) flakes onto the surfaces of graphene oxide (GO) sheets, which allows precise control of the resulting lamellar nanoarchitecture by in situ crystallization, is reported. GO sheets are utilized as nucleation sites that promote the optimized crystal growth of NiCNNi flakes. The NiCNNi- coated GO sheets then self-assemble and are stabilized as ordered lamellar nanomaterials. Regulated thermal treatment under nitrogen results in a Ni 3 C–GO composite with a similar morphology to the starting material, and the Ni 3 C–GO composite exhibits outstanding electrocatalytic activity and excellent durability for the oxygen reduction reaction. For the further development of functional materials, a smart approach to the assembly of functional 2D materials into well-defined 3D structures is critical. The best strategy for this purpose is layer-by-layer (LbL) assembly that can provide well-designed alternating layered structures with nanoscale precision from a variety of functional components. [1] For example, methodologies to create artificial layered structures often lead to materials with high-level functions that cannot be predicted based on the identity of the original compo- nents. [2] However, most of the previous strategies have several disadvantages: 1) in many cases, interlayer materials are nonfunctional polymers and often degrade the functionality of the main components; 2) step-by-step layering processes could be disadvantageous for construction of substantially thicker materials. Although pioneering approaches for non- interlayer-polymer LbL processes have been recently pro- posed, [3] these disadvantages have not yet been properly addressed. In the novel strategy presented here, we have exploited the layering capabilities of coordination polymers [4] as an interlayer adhesive in a spontaneous self-constructive process implemented in one pot. Typically, nickel-based cyano- bridged coordination polymers (NiCNNi) are deposited on the surface of graphene oxide (GO) sheets. During this reaction (Figure 1), GO sheets spontaneously assemble through binding of NiCNNi flakes in the one-step construc- tion of heterogeneous layered structures whose components all have some potentially useful functionality. In addition, the GO sheets serve not only as building units but also as nucleation sites for the growth of the NiCNNi flakes. Thermal treatment of the layered assembly causes successful conver- sion of the NiCNNi components to Ni 3 C with retention of the original LbL structure, since the inserted GO layers prevent random fusion of the metal source. Figure 1. Formation process of NiCNNi–GO hybrids (composites) through layer-by-layer assembly of graphene oxide sheets held together by coordination polymers, and thermal conversion to the Ni 3 C–GO hybrid (composite). Cross-sectional TEM images of NiCNNi–GO hybrid and Ni 3 C–GO hybrid and the crystal structure of Ni(H 2 O) 2 - [Ni(CN) 4 ]·4 H 2 O (NiCNNi) between the GO sheets are also shown. [*] M.B. Zakaria, B. Jiang, Prof. Y. Yamauchi Faculty of Science and Engineering, Waseda University 3-4-1 Okubo, Shinjuku, Tokyo, 169-8555 (Japan) E-mail: Yamauchi.Yusuke@nims.go.jp M. B. Zakaria, Dr. C. Li, Dr. Q. Ji, B. Jiang, Dr. S. Tominaka, Dr. Y. Ide, Dr. J.P. Hill, Prof. K. Ariga, Prof. Y. Yamauchi World Premier International (WPI) Research Center for Materials Nanoarchitechtonics (MANA) National Institute for Materials Science (NIMS) 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan) E-mail: Ariga.Katsuhiko@nims.go.jp Dr. Q. Ji Herbert Gleiter Institute of Nanoscience Nanjing University of Science & Technology 200 Xiaolingwei, Nanjing 210094 (China) Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under http://dx.doi.org/10. 1002/anie.201603223. A ngewandte Chemi e Communications 1 Angew. Chem. Int. Ed. 2016, 55,1–6  2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim These are not the final page numbers! Ü Ü