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

Ni (1wt%)-, Pt (1wt%)- and [Ni (0.5wt%)/Pt (0.5wt%)]-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) (3-95nm in diameter) which are hosted by the TiO2 framework. The resulting composites exhibit a rather large surface area, in the range of 186-200m2/g. The band gap energy reduces from 3.03eV for the undoped TiO2 to 2.15eV 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.