Theoretical and experimental research of novel fluorine doped hierarchical Sn3O4 microspheres with excellent photocatalytic performance for removal of Cr(VI) and organic pollutants

Abstract

The fluorine doped Sn 3 O 4 strengthened the redox potential. Moreover, the phenols and Cr(VI) acted as sacrificial agent of h + / OH and e − , respectively, which remarkably enables the efficient utilization of photoinduced electron-hole pairs. • The unique fluorine doped hierarchical Sn 3 O 4 microspheres were first reported. • F doping enhanced light harvesting and boosted active radical generation. • Low recombination rate of free charge carrier was obtained. • F-Sn 3 O 4 microspheres are promising for removing organic pollutants and Cr(VI). Here, novel fluorine doped Sn 3 O 4 microspheres with highly photocatalytic performance were reported. UV–vis diffuse reflectance spectrum (DRS) and transient photocurrent response test showed the enhanced light harvesting and photo-response. DRS and electron spin resonance (ESR) spectrum confirmed that the enhanced light harvesting could remarkably boost active radical generation. The low recombination rate of free charge carrier and the long lifetime of photon-generated carrier also made great contribution. The lifetime of photon-generated carrier of F 0.2 -Sn 3 O 4 was 1.38 μs, which was 2.76 times of Sn 3 O 4 (0.50 μs). F 0.2 -Sn 3 O 4 reduced 95% of 10 ppm Cr(VI) (pH = 7) under light irradiation (400 W metal halogen lamp, light intensity: 148.36 mW/cm 2 ) for 12 min, which was 3.6, 10.2 and 64.5 times higher than that of Sn 3 O 4 (25.83%), C 3 N 4 (9.25%) and commercial TiO 2 (1.47%), respectively. F 0.2 -Sn 3 O 4 could remove 98% of methyl orange within 4 min comparing with commercial TiO 2 (30%). The highly removing efficiency of phenols (phenol, bisphenol A and p-chlorophenol) was also obtained. Density functional theory (DFT) calculation, Powder X-ray diffraction (XRD) patterns and DRS revealed that the replacement of F − by O 2− enhanced the light harvesting. The work is promising for the synergistic treatment of industrial waste water with organic pollutants (phenols) and Cr(VI).