Integration of manganese-cobalt oxide nanoparticles into mesoporous Bi2WO6 n-n heterojunction for enhanced reductive removal of Hg(II) ions

Abstract

Industrial contamination has harmed aquatic life by throwing huge quantities of toxic inorganic metals ions, especially Hg(II) ions into the ecosystem. Thus, it is critical demand to remove Hg species in industrial wastewater to match the safety standards. In this contribution, n-n heterojunction MnCo₂O₄/Bi₂WO₆ nanocomposites were fabricated using the sol–gel process utilizing Pluronic P-105 as a structure-directing agent. The photocatalytic Hg(II) reduction has been conducted over MnCo₂O₄/Bi₂WO₆ nanocomposites under illumination. The prepared MnCo₂O₄/Bi₂WO₆ photocatalysts exhibited better photocatalytic activity for reduction Hg(II) under visible illumination in comparison to bare Bi₂WO₆ NPs. Among the obtained photocatalysts, the optimum 6 %MnCo₂O₄/Bi₂WO₆ nanocomposite exhibited superior photocatalytic ability at about 100 % after 40 min. The rate constant of 6 %MnCo₂O₄/Bi₂WO₆ photocatalyst is 0.1177 min⁻¹, which is almost 3.03 times greater than that of Bi₂WO₆ (0.0388 min⁻¹). Moreover, the MnCo₂O₄/Bi₂WO₆ nanocomposite maintained its photocatalytic ability during five consecutive cycles. The mesostructure and S-scheme mechanism of MnCo₂O₄/Bi₂WO₆ nanocomposite promotes light absorption, high separation rate of carriers, and charge transport. The construction strategy of the obtained photocatalyst provides a feasible route for accelerating the practical abstraction of toxic Hg(II) ions.