Unveiling the effect of growth time on bifunctional layered hydroxide electrodes for high-performance energy storage and green energy conversion

Abstract

Tailoring the properties of transition metal-based layered double hydroxides is inevitable for high-performance energy storage and efficient urea-electro-oxidation reaction (UOR) for effectively harnessing energy from urea-rich wastewater. Herein, the effect of growth time on the bi-functional properties of NiCo layered double hydroxide (Ni–Co LDH) is unveiled. Under the optimum growth time, the NiCo LDH electrode shows an excellent specific capacity of 210.5 mA h g⁻¹ at 2.5 mA cm⁻², outperforming many binder-free electrodes reported previously. Further, an asymmetric supercapacitor (ASC) is fabricated, exhibiting exceptional energy storage capabilities in terms of a specific capacitance of 77.7 F g⁻¹, energy density of 22.6 W h kg⁻¹, and excellent cycling stability with capacity retention of 86.8%. The ASC is encapsulated with a 3D-printed casing to power miniature electronics. The as-synthesized electrode was explored as an efficient electrocatalyst for the UOR. The lower onset potential with optimized catalytic behavior paves the way for green energy harvesting from urea-rich water through efficient UOR. The controlled growth morphology and reaction time influence the UOR and energy storage efficiency of the bimetallic LDH. This study provides meaningful insights into the tailor-made performance enhancement of bi-functional electrodes for energy storage and efficient energy conversion.