摘要
The thermolysis of metal-organic frameworks(MOFs)opens a new window for the fabrication of oxide semiconductors due to its simplicity,low cost and large-area uniformity of the resulting material.However,this approach usually requires high annealing temperatures over 350°C.In this work,sub-micro hierarchical porous Co_(3)O_(4)dodecahedra were synthesized by the thermolysis of zeolitic imidazolate frameworks 67(ZIF-67)at a low temperature of 268°C assisted by ammonium perchlorate(AP),in which ZIF-67 was employed as a metal source and a sacrificial template.The formation mechanism was probably attributable to the generation of Co-O bonds between the Co atom of ZIF-67 and the O atom of AP at lower temperatures which can accelerate the weakening of Co-N bonds of ZIF-67 and thus lead to an abrupt decomposition of ZIF-67 at 268°C.More importantly,the generation of the Co-O bond and the weakening of the Co-N bond were identified using the FTIR,Raman and XPS results.As confirmed by DFT results,ZIF-67 can be decomposed into Co_(3)O_(4)at lower temperatures assisted by AP than that in air.In addition,the obtained sub-micro hierarchical porous Co_(3)O_(4)dodecahedra showed a very large specific surface area of 106.11 m^(2)g^(-1),much larger than that in previous reports.Therefore,this work can provide a novel atomic insight into the formation mechanism of Co_(3)O_(4)hierarchical porous structures derived from ZIF-67 with AP at lower temperatures and also an energy-efficient method to synthesize porous metal oxide structures.
基金
Nature Science Foundation of China(No.51572075)
Open Foundation of the State Key Laboratory of Silicate Materials for Architectures at WUT(No.SYSJJ2018-05)。
