Synthesis of a bicontinuous structured SrTiO₃ porous film with significant photocatalytic activity by controlling phase separation process

A series of hierarchically porous SrTiO₃ films with different pore structure characteristics from bicontinuous macroporous–mesoporous structure to ordered and fragmented structures have been synthesized using sol–gel method, by controlling the competition between polyethylene glycol (PEG)-induced phase separation and sol–gel transition. Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) analysis, X-ray diffractometry (XRD) and photoluminescence (PL) spectroscopy were used to characterize the as-prepared samples. The bicontinuous structured SrTiO₃ porous film constructed by irregular grains possessed three-dimensional (3D) interconnected network with both macropores (80–400 nm) and mesopores (1–10 nm), which provides abundant active sites (the specific surface area up to 121.9 m²/g) and ensures fast mass transfer simultaneously. In addition, PL spectra illustrated that the film consisting of 3D bicontinuous macroporous– and mesopores has a relatively low photocarrier recombination rate. As a result, the SrTiO₃ film with 3D bicontinuous porous structure exhibits more outstanding photocatalytic behavior with high degradation capability for Rhodamine B (RhB) (99.8% after 90 min irradiation by 500 W mercury lamp) than the others. Moreover, nearly 80% of the degradation efficiency can be achieved after five cycles.