High-performance cauliflower-like Er₂O₃/NiO nanocomposite derived from Er-Ni-MOF for energy conversion and storage applications

With the growing urgency to address environmental degradation, the demand for clean energy has intensified the need for renewable energy production and high-performance energy storage systems. Current challenges in these fields include developing cost-effective and scalable materials that simultaneously enhance hydrogen production and serve as a supercapacitor electrode material. In this work, we have synthesized Er-Ni-MOF derived Er₂O₃/NiO nanocomposite showing multifunctional electrocatalytic properties with superior performance. The synthesized nanocomposite showed an enhancement of surface area along with improved conductivity. Er₂O₃/NiO nanocomposite showed a significantly low overpotential of 160 mV to reach a current density of 10 mA cm⁻² with fast reaction kinetics, and long-term durability. Moreover, Er₂O₃/NiO nanocomposite-based supercapacitor electrode with a specific capacitance (C_s) of 2139 F g⁻¹ showcased over two folds higher energy storage capacity compared to precursor Er-Ni-MOF and six times greater than Ni-MOF at a current density of 1 A g⁻¹. The fabricated electrode presented an excellent cyclic stability of ∼83 % for 8000 cycles. An asymmetric supercapacitor device was constructed using the MOF-derived Er₂O₃/NiO nanocomposite, as the positive electrode and activated carbon as the negative electrode material. The device exhibited a specific capacitance of 67.5 F g⁻¹ at a current density of 1 A g⁻¹, with an impressive capacity retention of 97 % over 15,000 cycles. These findings underscore the significance of MOF-derived nanocomposites and their potential for sustainable energy production and practical energy storage applications.