Exposed Crystal Surface-Controlled the Band Gap and Photocatalytic Activity of SrTiO₃ Photocatalyst for the Degradation of Tetracycline Hydrochloride

A hydrothermal method has been used to synthesize the SrTiO₃ photocatalyst with the crystal planes exposed (100) and (110) by addition ethyl alcohol and ethylene glycol, respectively. Various characterization methods confirmed that the synthesized SrTiO₃ is cubic phase, contains only Sr–Ti–O and Ti–O functional groups, and does not contain any other impurities. The particles of SrTiO₃ exposed to the (100) crystal plane are approximately spherical and agglomerate obviously, with an average particle size of about 80 nm. The particles of SrTiO₃ exposed to the (100) crystal plane are approximately cuboid, the particles are uniformly dispersed and the average particle size is about 60 nm. The SrTiO₃ photocatalyst exposed to (100) crystal planes showed high photocatalytic activity, and the degradation rate was 2.76 times that of the SrTiO₃ photocatalyst exposed to (100) crystal planes. The optimal catalyst content, drug concentration, and pH values of SrTiO₃ photocatalyst exposed to (100) crystal planes for the degradation of tetracycline hydrochloride under simulated sunlight irradiation are 1 g/L, 50 mg/L, and 9, respectively. The holes, hydroxyl radicals and superoxide radicals play dominant role in the degradation of tetracycline hydrochloride by SrTiO₃ photocatalyst exposed to (110) crystal plane.