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.

Bimetal phosphates, especially those with hollow structures, have been recognized as promising materials for energy storage application. However, research on hollow bimetal phosphates is quite rare because of the difficulty in controlling the preparation process. In this work, through a shell-coating and then controllable etching process, a nonspherical hollow bimetal (Co/Ni) phosphate nanocage (named ZIF-67-LDH-CNP-110) is successfully constructed for the first time, to the best of our knowledge. When utilized as an electrode material for supercapacitor application, the as-prepared nanocages exhibit a high specific capacitance of 1616 F g −1 at 1 A g −1 and excellent ratio capability of remaining 80.32% of initial capacitance at a high current density of 10 A g −1 . In addition, the as-fabricated ZIF-67-LDH−CNP-110//AC hybrid supercapacitor presents a remarkable energy density of 33.29 Wh kg −1 at a power density of 0.15 kW kg −1 .

A highly hydrophobic Cu(ii) MOF (UPC-21) was synthesized through a newly developed “diauxic growth” strategy. The multi-aromatic hydrocarbon units in the framework are responsible for hydrophobic character of UPC-21. Its application on water purification and oil/water separation was studied for the first time.

Developing low-cost, efficient, and stable trifunctional electrocatalyst for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) is still a significant challenge. Herein, this study reports a zeolitic imidazolate framework (ZIF) derived trifunctional electrocatalyst, composed of Co 5.47 N and Co 7 Fe 3 (CoFeN) that embedded into 1D N-doped carbon nanotubes modified 3D cruciform carbon matrix (NCNTs//CCM). Benefiting from the robust interfacial conjugation of Co 5.47 N/Co 7 Fe 3 and the 1D/3D hierarchical structure with a large surface area, the as-prepared CoFeN-NCNTs//CCM display trifunctional electrocatalytic activity for ORR (half-wave potential of 0.84 V), OER (320 mV at 10 mA cm -2 ), and HER (−151 mV at 10 mA cm -2 ). The assembled Zn-air battery exhibits high power density (145 mW cm -2 ) , enhanced charge-discharge performance (voltage gap of 0.76 V at 10 mA cm -2 ), and long-term cycling stability (over 445 h). The resultant overall water-splitting cell achieves a current density of 10 mA cm -2 at 1.63 V, which can compete with the best reported trifunctional catalysts. What is more, the self-assembled Zn-air batteries are utilized to power the overall water splitting successfully, verifying great potential of the CoFeN-NCNTs//CCM as functional material for sustainable energy storage and conversion system.