Heterojunction assembled CoO/Ni(OH)₂/Cu(OH)₂ for effective photocatalytic degradation and supercapattery applications

Mixed multimetallic-based nanocomposites have been considered a promising functional material giving a new dimension to environmental remediation and energy storage applications. On this concept, a hybrid ternary CoO/Ni(OH)₂/Cu(OH)₂ (CNC) composite showing sea-urchin-like morphology was synthesized via one-pot hydrothermal approach, and its photocatalytic and electrochemical performances were investigated. The photocatalytic performance was explored using Congo red (CR) as a dye pollutant under visible light illumination. The presence of mixed phases of ternary metal ions could minimize the recombination efficacy of photogenerated charge carriers on the basis of the heterojunction mechanism, resulting in 90% degradation of CR dye (40 mg L^-1). The effect of scavengers coupled with electrochemical experiments revealed O₂^-. radical as the predominating species responsible for the degradation of CR. From the electrochemical analysis of CNC, the well-distinguished redox peaks indicated the redox-type nature with a specific capacity of 405 C g^-1. For practical applications, an supercapattery (CNC( +)|KOH|AC( -)) was assembled furnishing an energy density of 42 W h kg^-1 at a power density of 5160 W kg^-1 at 5 A g^-1 along with a high capacity retention and coulombic efficiency of 98.83% over 5000 cycles.