Pseudomorphic conversion of metal–organic frameworks (MOFs) enables the fabrication of nanomaterials with well-defined porosities and morphologies for enhanced performances. However, the commonly reported calcination strategy usually requires high temperature to pyrolyze MOF particles and often results in uncontrolled growth of nanomaterials. Herein, we report the controlled alkaline hydrolysis of MOFs to produce layered double hydroxide (LDH) while maintaining the porosity and morphology of MOF particles. The preformed trinuclear M3(μ3-OH) (M = Ni2+ and Co2+) clusters in MOFs were demonstrated to be critical for the pseudomorphic transformation process. An isotopic tracing experiment revealed that the 18O-labeled M3(μ3-18OH) participated in the structural assembly of LDH, which avoided the leaching of metal cations and the subsequent uncontrolled growth of hydroxides. The resulting LDHs maintain the spherical morphology of MOF templates and possess a hierarchical porous structure with high surface area (BET surface area up to 201 m2·g–1), which is suitable for supercapacitor applications. As supercapacitor electrodes, the optimized LDH with the Ni:Co molar ratio of 7:3 shows a high specific capacitance (1652 F·g–1 at 1 A·g–1) and decent cycling performance, retaining almost 100% after 2000 cycles. Furthermore, the hydrolysis method allows the recycling of organic ligands and large-scale synthesis of LDH materials.

Supercapacitors are regarded to be highly probable candidates for next-generation energy storage devices. Herein, a bimetallic Co/Ni MOF is used as a sacrificial template through an alkaline hydrolysis and selective oxidation process to prepare an accordion-like ternary NiCoO/β-Ni Co(OH)/α-Ni Co(OH) composite, which is composed of Co/Ni(OH) nanosheets with large specific surface as the frame and NiCoO nanoparticles with high conductivity as the insertion, for supercapacitor application. This material exhibits both high specific capacitance (1315 F·g at 5 A·g) and excellent cycle performance (retained 90.7% after 10 000 cycles). This hydrolysis-oxidation process, alkali hydrolysis followed by oxidation with HO, offers a novel approach to fabricate the Ni/Co-based electrode materials with enhanced supercapacitor performance.

ZIF-8 and ZIF-67 exhibit different thermolysis natures based on the in situ structural characterization techniques.

ZIF-8 is an easily synthesized porous material which is widely applied in gas storage/separation, catalysis, and nanoarchitecture fabrication. Thermally induced atomic displacements and the resultant framework deformation/collapse significantly influence the application of ZIF-8, and therefore, in situ temperature dependent FTIR spectroscopy was utilized to study the framework changes during heating in the oxidative environment. The results suggest that ZIF-8 undergoes three transition stages, which are the lattice expansion stage below 200 °C, the "reversible" structural deformation stage from 200 to 350 °C, and the decomposition/collapse stage over 350 °C. Our research indicates that the Zn-N bond breaks at a temperature of 350 °C in the oxidant environment, leading to a drastic deformation of the ZIF-8 structure.