A facile one-pot synthesis of TiO2-based nanosheets loaded with MnxOy nanoparticles with enhanced visible light–driven photocatalytic performance for removal of Cr(VI) or RhB.

This paper reports a facile one-pot approach for Mn x O y (Mn = Mn 2+ , Mn 3+ ) loaded TiO 2 -based nanosheets (Mn–TNSs) with surface enrichment of Mn x O y nanoparticles via a simple hydrothermal route. The as-synthesized samples showed clearly sheet-like structure, with high specific surface area (200–300 m 2 /g) and small thickness (ca. 4 nm). The small Mn x O y nanoparticles with uniform size (1–2 nm) were highly dispersed on the surface of the TNSs. Loaded Mn x O y not only have influenced the crystal structure and surface area of the TNSs, but also resulted in considerable enhancement of visible-light absorption and red-shift for TNSs. The results of X-ray photoelectron spectroscopy showed that Mn 2+ and Mn 3+ co-exist in Mn–TNSs. The loading of Mn x O y on TNSs resulted in changes in binding energies of Ti and O. The concentration of Ti 3+ increased gradually with the amount of loaded Mn x O y increasing. The photo-reactivity of the samples were evaluated by measuring the formation of photo-induced hydroxyl radical ( OH) using coumarin (COU) as a probe molecule and photocatalytic degradation of Rhodamin B (RhB) and dichromate (Cr(VI)) under visible-light irradiation. It has been found that the Mn–TNSs photocatalysts showed better visible-light photocatalytic activity for aqueous RhB or Cr(VI) solution. The photocatalytic activity gradually increased with the content of Mn x O y increasing initially, and then decreased after attaining a maximum value at an optimal content (2.5 at.%) of Mn x O y in TNSs for degradation of aqueous RhB or Cr(VI) solution, respectively. The cyclic tests that performed five times demonstrated high stability and recyclable usability of the photocatalysts. A possible alternate mechanism for the enhancement of the photocatalytic activity under visible-light irradiation was also proposed. [ABSTRACT FROM AUTHOR]