Silica hydrogel-mediated dissolution-recrystallization strategy for synthesis of ultrathin α-Fe2O3 nanosheets with highly exposed (1 1 0) facets: A superior photocatalyst for degradation of bisphenol S

Abstract

We have developed a silica hydrogel-mediated dissolution-recrystallization method that can not only significantly facilitate the growth of α-Fe2O3 in the a-b plane but also effectively impede its growth along the c-axis, thus leading to the formation of ultrathin α-Fe2O3 nanosheets with highly exposed (110) facets. When used as visible light photocatalysts for water remediation, the degradation rate constant of bisphenol S (BPS) achieved by the α-Fe2O3 nanosheets reaches to 0.0164min−1, which is 16.4 and 2.6 folds higher than that of α-Fe2O3 nanoparticles and commercial TiO2, respectively. The apparent quantum efficiency of the α-Fe2O3 nanosheets is 3.82%, which is 4.5 and 1.9 folds higher than that of the α-Fe2O3 nanoparticles and commercial TiO2, respectively. Such impressive enhancement in photoreactivity is attributed to the advantageous properties of the α-Fe2O3 nanosheets such as efficient charge separation and high surface area, which are originated from the rationally designed nanoarchitectures (i.e., ultrathin sheet-like nanostructures with a high percentage of (110) facets). The corresponding catalytic oxidation mechanism has been proposed on the basis of photoluminescence spectra, electron paramagnetic resonance spectra and classical quenching tests. The degradation byproducts of BPS have been identified and the corresponding transformation pathways have also been proposed.