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.

Photocatalytic performance of BiFeO3 based on MOFs precursor

“…The organic components could provide abundant nanopores when they are removed through simple thermal treatment . The metal oxides with porous and large specific surface area prepared by thermal decomposition MOFs precursor has become a hot research topic in recent years …”

Self‐Construction from 2D to 3D: One‐Pot Layer‐by‐Layer Assembly of Graphene Oxide Sheets Held Together by Coordination Polymers

“…This behavior is evidence of gradual growth of the NiCNNi flakes. [6] After the growth of NiCNNi flakes on the GO sheets,t he relative peak intensity corresponding to 121 peak is weakened. In the case of GO,adiffraction peak at 2q (ca.…”

“…Thediffraction peaks of the NiCNNi flakes are assignable to an orthorhombic system and clearly match Hofmann-type NiCNNi with 2D layered structure. [6] After the growth of NiCNNi flakes on the GO sheets,t he relative peak intensity corresponding to 121 peak is weakened. This observation can be explained by preferential crystal growth on the GO sheets.…”

“…NiCNNi flakes prepared in the absence of GO sheets exhibit an average lateral size of around 150 nm ( Figure S2c) combined with the periodic spots from the electron diffraction (ED) patterns reveal that the flakes are highly crystallized. [6] Thesurface morphology of the NiCNNi-GO hybrid was examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the results are shown in Figure 2. From these images,i tc an be clearly observed that the NiCNNi flakes have grown horizontally at the surfaces of the GO sheets with flakes apparently encapsulated between the larger GO sheets.T he selected-area ED pattern indicates that the crystalline structures of both NiCNNi and GO are preserved even after hybridization ( Figure 2b).…”

Shape-controlled synthesis of mesoporous iron phosphate materials with crystallized frameworks

“…11 The use of non-aqueous solvents is also an effective strategy for decreasing the reactivity of metal precursors. Although there are a few reports published on the successful synthesis of mesoporous transition-metalbased oxide and chalcogenide materials with controlled shapes, 3,[15][16][17] there have been no reports on transition-metal-based phosphate materials due to the rapid condensation reaction of the precursors. 14 The aim of all the above procedures is to delay the rapid condensation reactions of the inorganic precursors, which lead to the formation of bulk materials and uncontrolled phase separation between the organic and inorganic components.…”