Deep-eutectic solvent-assisted synthesis of bismuth tungstate microsphere impregnated with rGO for the maximization of 4-nitrophenol and acid orange 10 degradation through photocatalysis

Abstract

The work aimed to develop and investigate an effective photocatalyst of reduced graphene oxide (rGO)-modified bismuth tungstate (Bi₂WO₆, BW) using a deep eutectic solvent. Many methods including powder XRD, FT-IR, SEM, HRTEM, EDXS, HR-XPS, PL, EIS, and UV–visible DRS, are employed to investigate structural, morphological, chemical, and optical properties. The rGO-modified Bi₂WO₆ catalyst had the maximum photocatalytic efficiency on 4-nitrophenol (4-NP) and acid orange 10 (AO 10) degradation, with 93.54 % and 96.88 %, respectively. Scavenging studies found that holes (h⁺) are the dominant active species for the removal of AO 10, indicating that they are effectively implicated in photogenerated pollutant fragmentation. The heterostructure exhibited a lower charge recombination rate, which was owing to the fast transport of photoexcited electrons (eˉ) from the conduction band (CB) of the Bi₂WO₆ and contact between Bi₂WO₆ and rGO facilitated synergistic charge transfer. The photocatalyst demonstrated outstanding stability, retaining 89.43 and 90.62 % after 5 cycles of 4-NP and AO 10 degradation, respectively. The outcomes of the present research emphasized the practical employment of the rGO-modified Bi₂WO₆-DES heterostructure towards environmental remediation.