Nanostructured CeO₂/NiV–LDH composite for energy storage in asymmetric supercapacitor and as methanol oxidation electrocatalyst

High-performance electrochemical supercapacitors should demonstrate notably high energy density along with ultralong cycling life for wide commercial applications. Hence, significant efforts are being made to improve the specific capacitance as well as expand the operating voltage of the fabricated supercapacitor device. Herein, a novel quasi-solid-state asymmetric supercapacitor (ASC) device employing porous nanostructured CeO₂/NiV–LDH (2:2) composite positive electrode and 3D flowerlike Bi₂O₃ negative electrode is reported. The positive electrode material shows an efficiently improved electrochemical feature from synergistic integration between high surface area CeO₂ nanorods, and 2D NiV–LDH nanosheets with short diffusion distance for the charge carriers. In addition, the CeO₂/NiV–LDH (2:2) composite acts as highly active and stable electrocatalyst when investigated for the methanol electrooxidation. The as-fabricated gel electrolyte based quasi-solid-state CeO₂/NiV–LDH (2:2)//Bi₂O₃ ASC device exhibits an excellent and stable electrochemical performance (highest energy density of 62.5 Wh kg⁻¹ at a power density of 1595.2 W kg⁻¹) with long cycle life displaying 86.4% capacitance retention still after 10,000 GCD cycles. This work confirms the high suitability of the rare earth metal oxide and LDH-based composite electrode materials, as well as Bi chalcogenides, for the quasi-solid-state ASCs as proficient portable energy systems.