Post synthetic annealing of zeolitic imidazolate framework-67 for high-performance hybrid supercapacitors

The post-synthetic annealing (PSA) of metal–organic frameworks (MOFs) are getting more attention in preparing tunable porous materials for energy storage devices. Following this unique strategy, we synthesized and modified the surface texture of the nanostructured zeolite imidazolate framework (ZIF-67) via different annealing temperatures and utilized it as the supercapacitor electrode materials. In particular, the sample at temperature 300 °C (ZIF-67@300) achieved a large specific surface area (SSA) ~1869 m² g⁻¹ and exhibited a high specific capacity (C_sp) of 339 C g⁻¹ with better cyclic stability (~94%). Furthermore, a hybrid supercapacitor (HSCs) was assembled using ZIF-67@300 as a positive electrode and oxygen, nitrogen-enriched activated carbon (O, N@AC) as a negative electrode, which operates with a wide cell voltage of 1.5 V. Interestingly, the HSC showed a maximum device-specific capacitance (C_s) of 98 F g⁻¹ with high specific energy (E) of 30 Wh Kg⁻¹ and specific power (P) of 28323 W kg⁻¹, respectively. In addition, the HSCs revealed excellent cyclic stability of ~95% for 10,000 continuous galvanostatic charge/discharge (GCD) cycles. Thus, the remarkable electrochemical performance of ZIF-67@300 electrode material as a potential candidate for energy storage devices.