Exploring the Bifunctionality of Co3S4/NiS2/Cu2S Heterojunction Nanocomposites for Hybrid Supercapacitors and Double Z‑Scheme-Driven Dye Degradation.

A trimetallic heterojunction-derived Co₃S₄/NiS₂/Cu₂S with different ratios through a two-step hydrothermal method was successfully synthesized, showing multifunctional properties such as excellent electrochemical behavior and high photocatalytic activity. Both electrochemical and photocatalytic performances were optimized by adjusting the concentration of Cu without any change in Co and Ni concentrations. Among the synthesized nanocomposites, CNCS-0.15 (Co₃S₄^0.5/NiS₂^0.5/Cu₂S^0.15) depicted the maximum specific capacity of 464.16 C g^–1 at 1 A g^–1 as revealed from electrochemical measurements. Further for real-time usage, assembling of a hybrid supercapacitor CNCS-0.15-(+)||activated carbon(−) furnished an energy density of 84.95 W h kg^–1 at a power density of 1134 W kg^–1 with good capacity retention of 93.64% for 5000 cycles. In addition, CNCS-0.15 also displayed remarkable photocatalytic performance under visible light illumination by utilizing Congo red (CR) dye. It could effectively degrade 91% of CR (40 mg L^–1) through a double Z-scheme mechanism owing to the charge carriers' availability with higher redox ability. The Mott–Schottky analysis along with the scavenging experiment confirmed the involvement of h⁺ and O₂^–. radicals in the photodegradation. Due to highly interconnected nanoflake architectures, CNCS-0.15 holds a promising application as a supercapacitor electrode and visible light active photocatalyst. [ABSTRACT FROM AUTHOR]