Unleashing the Electrochemical/Photocatalytic Activity of Co₉Se₈/Ni₃Se₄/Cu₂Se Ternary Nanocomposites for Sustainable Energy Storage and Photo‐Fenton Based Pollutants Degradation

Abstract Rational designing of multicomponent selenide‐based composites such as Co 9 Se 8 /Ni 3 Se 4 /Cu 2 Se (CNCD) is synthesized through a simplistic hydrothermal method. Several standard characterization techniques are utilized to study the structural, morphological and elemental features of the obtained samples with varying selenide content. Both electrochemically and photocatalytic performance are amplified at an optimized selenide content denoted as CNCD‐0.5 due to its favourable characteristics and morphology. From the electrochemical measurements, the battery‐type performance of the CNCD‐0.5 is established from the well‐distinguished redox peaks. For practical utility, the assembled CNCD‐0.5 (+) // AC (−) device delivered an energy density of 35.97 Wh kg −1 at a power density of 1210.86 W kg −1 with a capacity retention of 91% for 5000 cycles of uninterrupted charge–discharge. Further, the photo‐Fenton‐based degradation experiments are assessed by demineralization of cationic RhodamineB (RhB) and anionic Tartrazine (Tz) dye using H 2 O 2 with the minimal dosage of catalyst (0.3 g L −1 ). At an optimized concentration of H 2 O 2 , CNCD‐0.5 can degrade 97.14% of RhB (40 mg L −1 ) and 94.77% of Tz (40 mg L −1 ) for 120 min of visible‐light illumination. Such designing of multinary metal selenides‐based nanocomposites holds promising potential for multifunctional applications due to the synergistic advancement in the composite properties.