Fabrication of Hierarchical Ni(OH)2@Ni3S2/NF Electrode from PBAs‐based Composite with Enhanced Electrochemical Capacitive and Electrocatalytic Properties

Developing high-efficiency, cost-effective, and durable electrodes is significant for electrochemical capacitors and electrocatalysis. Herein, a 3D bifunctional electrode consisting of nickel hydroxide nanosheets@nickel sulfide nanocubes arrays on Ni foam (Ni(OH)2 @Ni3 S2 /NF) obtained from a Prussian blue analogue-based precursor is reported. The 3D higher-order porous structure and synergistic effect of different compositions endow the electrode with large specific surface area, facile ion/electron transport path, and improved conductivity. As a result, the Ni(OH)2 @Ni3 S2 /NF electrode exhibits a high specific capacity of 211 mA h g(-1) at a current density of 1 A g(-1) and 73 % capacity retention after 5000 cycles at 5 A g(-1) . Moreover, the Ni(OH)2 @Ni3 S2 /NF electrode has superior electrocatalytic activity for the hydrogen evolution reaction with low overpotentials of 140 and 210 mV at current densities of 10 and 100 mA cm(-2) , respectively. The synthetic strategy for the unique higher-order porous structure can be extended to fabricate other composite materials for energy storage and conversion.