Controllable Tuning of Cobalt Nickel-Layered Double Hydroxide Arrays as Multifunctional Electrodes for Flexible Supercapattery Device and Oxygen Evolution Reaction

The rational design and fabrication of promising electrodes with prominent energy storage property and conversion performance is crucial for supercapacitors and electrocatalysis. Herein, potato chip-like cobalt nickel-layered double hydroxide@polypyrrole-cotton pad (CoNi-LDH@PCPs) composite was synthesized by in situ polymerization, which was coupled with facile solution reaction and ion-exchange etching process. An interesting potato chip-like structure can effectively expedite the kinetics of the electrode reactions, while the three-dimensional PCPs texture affords efficient pathways for charge transport, and the voids between adjacent fibers are thoroughly accessible for electrolytes and bubble evolution. When evaluated as a positive electrode for wearable supercapattery, the hierarchical CoNi-LDH@PCPs electrode displayed high specific capacity and excellent flexibility. As an oxygen evolution reaction catalyst, this PCP-based electrode also reveals the lowest overpotential of 350 mV at 10 mA cm^-2 and a Tafel slope of ∼58 mV dec^-1. In addition, density functional theory calculations suggest that the synthesis strategy for controllable tuning of hollow CoNi-LDH arrays reported here represents a critical step toward high-performance electrodes for energy storage and electrochemical catalysis.