Influence of selenium precursors on the formation of iron selenide nanostructures (FeSe₂): Efficient Electro-Fenton catalysts for detoxification of harmful organic dyestuffs

In this investigation, a sequences of iron diselenide (FeSe₂) nanomaterials as the competent and highly stable catalysts for the detoxification of aqueous organic dye pollutants such as Congo red (CR) and methylene blue (MB) through Electro-Fenton (EF) process using hydrogen peroxide as an initiator have been studied. The utilized selenium precursors include selenium metal, selenious acid (H₂SeO₃) and selenium dioxide (SeO₂) which were employed for the synthesis of FeSe₂ catalysts through a wet chemical strategy. It has been observed that based on the employed precursors, different morphologies ranges of the FeSe₂ catalysts were obtained: microgranualr particles to nano-stick to nanoflakes. The crystalline nature and phase purity of the obtained FeSe₂ catalysts were determined through XRD, Raman and HR-TEM analyses which confirmed their orthorhombic ferroselite structure. Among the prepared FeSe₂ catalysts, FS-2 (using H₂SeO₃) displayed better porous properties as compared to other catalysts and achieved the highest surface area of 74.68 m²g^-1. The narrow bandgap (0.88 eV) and fast conversion of Fe²⁺/Fe³⁺ cycle of FeSe₂ led CR and MB degradation of 93.3% and 90.4%, respectively. The outcome of this study demonstrates improved catalytic properties of FeSe₂ nanostructures for the efficient detoxification of hazardous and toxic effluents.