Hierarchically porous trimetallic hydroxide arrays for aqueous energy storage and oxygen evolution with enhanced redox kinetics

Improving the electrochemical reaction kinetics is of great importance but remains challenging for the applications of hydroxide materials in the field of energy conversion and storage. Through rational nanostructure design with modified compositions, herein, a hierarchical scale-like trimetallic hydroxide (CuCoNi-OH) array is synthesized using a novel bimetallic 2D-zeolitic imidazolate framework (CuCo-ZIF-L) as structure-inducing template under a moderate alkaline hydrolysis strategy. The hierarchical and porous structure offers large exposure of active sites and rapid electrolyte diffusion, and the multi-metallic synergistic effect provides high electrical conductivity and fast redox transformation, both promoting the electrochemical reaction kinetics of supercapacitor and oxygen evolution reaction (OER). When evaluated as a battery-type electrode, the CuCoNi-OH electrode delivers a high specific capacity of 821.6 C g-1 at 1 A g-1 with capacity retention of 89.8% at 20 A g-1, and the assembled hybrid supercapacitor exhibits high energy density and power density. Moreover, the CuCoNi-OH electrode also shows competitive OER activity with a low overpotential of 290 mV at 10 mA cm-2. This strategy demonstrates its universality in the fabrication of bimetallic ZIF-L and corresponding metallic hydroxides, and opens a new approach for the rational design of high-performance materials for electrochemical energy storage and conversion applications.