High-performance photocatalytic reduction of Cr(VI) using a retrievable Fe-doped WO ₃/SiO ₂ heterostructure

Abstract

The enhancement of the photocatalytic performance of pristine WO ₃ was systematically adjusted due to its fast recombination rate and low reduction potential. A designed heterostructure photocatalyst was necessarily synthesised by Fe ³⁺ metal ions doping into WO ₃ structure with and composition modification. In this study, we synthesised a retrievable Fe-doped WO ₃/SiO ₂ heterostructure using a surfactant-assisted hydrothermal method. This heterostructure was then employed as an effective photocatalyst for the removal of Cr(VI) under visible light irradiation. Enlarged photocatalytic reduction was observed over a synergetic 7.5 mol% Fe-doped WO ₃/SiO ₂-20 nanocomposite, resulting in dramatically increased activity compared with undoped WO ₃ and SiO ₂ nanomaterials under visible light illumination within 90 min. The presence of 7.5 mol% Fe ³⁺ ion dopant in WO ₃ optimised electron–hole recombination, consequently reducing WO ₃ photocorrosion. After adding SiO ₂ nanoparticles, the binary WO ₃-SiO ₂ nanocomposite played roles as both adsorbent and photocatalyst to increase specific surface area. Thus, the 7.5 mol% Fe-doped WO ₃/SiO ₂-20 nanocomposite catalyst had more active sites on the surface of catalyst, and enhanced photocatalytic reduction was significantly achieved. The results showed 91.1% photocatalytic reduction over the optimum photocatalyst, with a photoreduction kinetic rate of 21.1 × 10 ^–3 min ⁻¹, which was approximately four times faster than pristine WO ₃. Therefore, the superior optimal photocatalyst demonstrated reusability, with activities decreasing by only 9.8% after five cycles. The high photocatalytic performance and excellent stability of our photocatalyst indicate great potential for water pollution treatments.

Supplementary Information

The online version contains supplementary material available at 10.1186/s11671-023-03919-0.