Kirkendall Effect Induced Ionic Liquid-Assisted Metal−Organic Framework-Derived NiCo-P Electrode and Redox Electrolyte: Their Synergistic Interface Enhancing the Supercapacitor and Hydrogen Evolution Reaction Performance

Abstract

Enhancing the performance of electrodes and electrolytes using ionic liquids (ILs) is a promising avenue for energy storage and conversion, yet it remains a significant challenge. In this comprehensive study, we highlight the crucial role of ionic liquids in the dual functionality of electrodes and electrolytes. Herein, NiCo-P derived from the metal−organic framework is synthesized with the assistance of 1-butyl-3-methylimidazoliumbis(trifluoromethylsulfonyl) imide (BMIM TFSI) ionic liquid, which induces the Kirkendall effect and results as a structural modifier. Additionally, the BMIM TFSI interacts with the KOH electrolyte to form π−OH interactions, facilitating fast reversible redox reactions at the electrolyte−electrode interface. The as-prepared NiCo-P electrode combined with the BMIM TFSI electrolyte delivers a high specific capacitance of 821 F g⁻¹ at a current density of 1 A g⁻¹ in a three-electrode system. The assembled IL-aided hybrid supercapacitor produced a high window potential of 1.4 V, a minimum energy density of 75.29 Wh kg⁻¹, and an excellent stability performance (97.9% after 12000 cycles). Furthermore, the NiCo-P electrocatalyst exhibited a low overpotential (99 mV at 10 mA cm⁻²) and small Tafel slope value (77 mV dec⁻¹) for hydrogen evolution reaction in the IL-bound KOH electrolyte. This study introduces a novel perspective on ionic liquids, which serve dual roles as both electrodes and electrolytes. This dual functionality synergistically enhances energy storage capacity and catalytic efficacy.