Morphology and temperature treatment control on photocatalytic and photoluminescence properties of SrWO4 crystal
This work reports the combined role of morphology and crystallization degree of strontium tungstate (SrWO4) scheelite structure on its photocatalytic and photoluminescence properties. The difference in precursor ratio lead to two morphologies, spindle and sphere, which remain unchanged with heat treatment up to 500°C. However, the crystallite size of as obtained and treated at 300 and 500°C samples are about 50–74 nm for spindles and 44–110 nm for spheres. Both morphologies and thermal treatment lead to the variation of photoluminescence and photodegradation of rhodamine (RhB) and methylene blue (MB) dyes under UV irradiation. Stronger photodegradation efficiency was found for RhB (90%) than MB (72%). The photoinduced mechanism is more significant for RhB and becomes more efficient for samples treated at high temperature, while MB photocatalysis is weak due to the adsorption process. A broad visible photoluminescence band was observed at room temperature and chromaticity coordinates were identified that confirmed the emission wavelength. The most intense photoluminescence was obtained for samples treated at 300°C, corresponding to the optimal disordered structures and accompanied by a redshift wavelength for both spheres and for spindles. In this case, the spindles showed the most intense photoluminescence, almost ten times higher than spheres.