A nanoporous interferometric micro-sensor for biomedical detection of volatile sulphur compounds

A simple one-step NaCl-assisted microwave-solvothermal method has been developed for the preparation of monodisperse α-Fe₂O₃ mesoporous microspheres. In this approach, Fe(NO₃)₃ · 9H₂O is used as the iron source, and polyvinylpyrrolidone (PVP) acts as a surfactant in the presence of NaCl in mixed solvents of H₂O and ethanol. Under the present experimental conditions, monodisperse α-Fe₂O₃ mesoporous microspheres can form via oriented attachment of α-Fe₂O₃ nanocrystals. One of the advantages of this method is that the size of α-Fe₂O₃ mesoporous microspheres can be adjusted in the range from ca. 170 to ca. 260 nm by changing the experimental parameters. High photocatalytic activities in the degradation of salicylic acid are observed for α-Fe₂O₃ mesoporous microspheres with different specific surface areas.