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 (Co3S40.5/NiS20.5/Cu2S0.15) 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

Electrochemical sensor based on green-synthesized iron oxide nanomaterial modified carbon paste electrode for Congo red electroanalysis and capacitance performance

In this study, a facile protocol was used to convert non-valuable orange peels (OP) waste into a new sensing iron oxide orange-peel nanomaterial (FeOP). The presence of iron oxide nanoparticles in the modified OP was confirmed by physicochemical characterisations including Fourier-transform infrared spectroscopy, X-ray diffractometry, thermogravimetry, and scanning electron microscopy-energy dispersive X-ray. FeOP was used to modify a carbon paste electrode (CPE/FeOP) which displayed a significant increase in specific capacitance of 2939 F.g−1, two folds higher than that obtained with CPE at 10 m.s−1 in NaCl. The electroanalysis of Congo red (CR) in aqueous solutions using CPE/FeOP displayed detection limits of 2.8 × 10−7 mol.L−1 and 8.2 × 10−7 mol.L−1 respectively in deionised and spring waters, in the linear range of 5 to 55 µM. CPE/FeOP electrochemical sensor is therefore suitable for the determination of Congo red in wastewater.</p