title: Controlled synthesis of nanoporous nickel oxide with two-dimensional shapes through thermal decomposition of metal-cyanide hybrid coordination polymers.
abstract: The urgent need for nanoporous metal oxides with highly crystallized frameworks is motivating scientists to try to discover new preparation methods, because of their wide use in practical applications. Recent work has demonstrated that two-dimensional (2D) cyanide-bridged coordination polymers (CPs) are promising materials and appropriate for this purpose (Angew. Chem. Int. Ed.- 2013, 52, 1235). After calcination, 2D CPs can be transformed into nanoporous metal oxides with a highly accessible surface area. Here, this strategy is adopted in order to form 2D nanoporous nickel oxide (NiO) with tunable porosity and crystallinity, using trisodium citrate dihydrate as a controlling agent. The presence of trisodium citrate dihydrate plays a key role in the formation of 2D nanoflakes by controlling the nucleation rate and the crystal growth. The size of the nanoflakes gradually increases by augmenting the amount of trisodium citrate dihydrate in the reaction. After heating the as-prepared CPs in air at different temperatures, nanoporous NiO can be obtained. During this thermal treatment, organic units (carbon and nitrogen) are completely removed and only the metal content remains to take part in the formation of nanoporous NiO. In the case of large-sized 2D CP nanoflakes, the original 2D flake-shapes are almost retained, even after thermal treatment at low temperature, but they are completely destroyed at high temperature because of further crystallization in the framework. Nanoporous NiO with high surface area shows significant efficiency and interesting results for supercapacitor application.
authors: Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan) http://www.yamauchi-labo.com; World Premier International (WPI) Research Center for Materials Nanoarchitechtonics (MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Department of Chemistry, Faculty of Science, Tanta University, Tanta, Gharbeya 31527 (Egypt).
authors: Mohamed B
authors: MB
authors: Zakaria
authors: Ming
authors: M
authors: Hu
authors: Rahul R
authors: RR
authors: Salunkhe
authors: Malay
authors: M
authors: Pramanik
authors: Kimiko
authors: K
authors: Takai
authors: Victor
authors: V
authors: Malgras
authors: Seyong
authors: S
authors: Choi
authors: Shi Xue
authors: SX
authors: Dou
authors: Jung Ho
authors: JH
authors: Kim
authors: Masataka
authors: M
authors: Imura
authors: Shinsuke
authors: S
authors: Ishihara
authors: Yusuke
authors: Y
authors: Yamauchi
mesh_terms: D001952:Bridged-Ring Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D003460:Crystallization; D003486:Cyanides / Q000737:chemistry*; D008670:Metals / Q000737:chemistry; D009532:Nickel / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D016062:Porosity
chemical_list: D001952:Bridged-Ring Compounds; D003486:Cyanides; D008670:Metals; D011108:Polymers; D009532:Nickel; C028007:nickel monoxide
keywords: controlled crystallization; material science; mesoporous materials; nanoporous materials; nickel oxide