Amorphous Intermediate Derivative from ZIF-67 and Its Outstanding Electrocatalytic Activity

Controlled Preparation of Hollow and Porous Co9S8 Microplate Arrays for High-Performance Hybrid Supercapacitors

The design and controlled preparation of hollow and porous metal sulfide arrays are an important issue for electrochemical energy storage and conversion because of their unique structural merits including large surface areas, shortened diffusion paths, and rich reaction sites. Herein, a hollow and porous Co₉S₈ microplate array (MPA) was successfully fabricated by a facile self-sacrifice template strategy, which involved the uniform growth of a metal-organic framework microplate template on Ni foam (NF) and annealing in air, followed by an anion-exchange reaction with S^2- ions. The resulting Co₉S₈-MPA/NF as a binder-free electrode for a supercapacitor shows a high specific capacitance of 1852 F g^-1 (926 C g^-1) at 1 A g^-1 and an excellent cycling stability (86% retention after 5000 cycles at 20 A g^-1). Moreover, a hybrid supercapacitor (HSC) constructed with Co₉S₈-MPA/NF and activated carbon exhibits an outstanding energy density of 25.49 Wh kg^-1 at a high power density of 800 W kg^-1 and a long-term stability of 92% capacitance retention after 5000 cycles at 10 A g^-1. It is worth noting that the prepared all-solid-state HSC can light a red light-emitting diode for 2 min, proving to be a great practical application prospect. These excellent electrochemical behaviors show that this effective conversion strategy offers more possibilities for the development of high-performance energy storage metal sulfide materials.

Engineering the valence state of ZIF-67 by Cu2O for efficient nonenzymatic glucose detection

The valence state regulation of Co-based electrocatalysts is extremely important and greatly challenging to enhance the electrochemical performance toward glucose oxidation.