MOF‐Templated Hollow NiCo‐LDH Nanocages via Alkali‐Free Green Conversion as High‐Capacity Supercapacitor Electrodes

Layered double hydroxides (LDHs) with hollow structures offer high theoretical specific capacity and short ion diffusion pathways, making them promising supercapacitor materials. However, constructing hollow NiCo‐LDH remains challenging because it typically relies on template or special reaction conditions that are often harsh, and the conventional preparation of LDHs itself requires large amounts of alkaline reagents. Herein, we report an alkali‐free nickel‐ion‐directed replacement reaction using ZIF‐67 as self‐sacrificing template to fabricate hollow NiCo‐LDH nanocages. Enabled by a Kirkendall‐effect‐mediated conversion process, this green strategy yields hollow dodecahedral nanocages providing abundant electroactive sites and facilitating rapid ion transport. The optimized electrode delivers a high specific capacity of 466.14 mAh g ⁻¹ at 1 A g ⁻¹ and retains 314.99 mAh g ⁻¹ at 10 A g ⁻¹ . Kinetic analysis reveals that the capacitive contribution increases from 52.8% at 5 mV s ⁻¹ to 83.3% at 100 mV s ⁻¹ , demonstrating excellent surface‐controlled charge storage. An asymmetric supercapacitor (NiCo‐LDH//AC) achieves a maximum energy density of 38.7 Wh kg ⁻¹ at 179.8 W kg ⁻¹ and retains 26.5 Wh kg ⁻¹ at 1798 W kg ⁻¹ , and powers an LED for over 100 min. This work offers a green, alkali‐free route to hollow bimetallic LDHs and highlights the potential of sustainable synthesis for high‐performance supercapacitors.