Ni-, Pt- and (Ni/Pt)-doped TiO2 nanophotocatalysts: A smart approach for sustainable degradation of Rhodamine B dye

摘要

Ni (1 wt%)-, Pt (1 wt%)- and [Ni (0.5 wt%)/Pt (0.5 wt%)]-doped TiO₂ nanoporous catalysts have been successfully obtained through a facile two-step hydrothermal route. TiO₂ crystallizes mostly in the anatase phase and acts as a mesoporous matrix. Meanwhile, Ni, Pt and Ni/Pt dopants form small nanoparticles (NPs) (3–95 nm in diameter) which are hosted by the TiO₂ framework. The resulting composites exhibit a rather large surface area, in the range of 186–200 m2/g. The band gap energy reduces from 3.03 eV for the undoped TiO₂ to 2.15 eV for the Pt-loaded TiO₂. As a consequence, absorption expands toward the visible light range. The photodegradation of Rhodamine B dye in aqueous medium has been investigated under UV–vis light irradiation. The presence of Ni, Pt and Ni/Pt NPs significantly enhances the photocatalytic activity of the material. Furthermore, the Ni-doped TiO₂ shows ferromagnetic behavior at room temperature, which makes its recovery and subsequent fast reutilization possible. Interestingly, this sample also exhibits the best stability upon recycling. Considering all the current challenges in sustainable water remediation, these new photocatalysts could find applications in real environmental contexts in the near future.