Hydrothermal preparation of Nb-doped NaTaO3 with enhanced photocatalytic activity for removal of organic dye

The construction of efficient photocatalysts has received much attention in wastewater treatment . In this study, Nb-doped NaTaO 3 was prepared with different doping ratio by a facile hydrothermal method. The prepared catalysts were analyzed by X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller (BET) theory, ultraviolet–visible diffuse reflectance spectroscopy. Then the synthesized catalysts were employed to degrade a model pollutant, methylene blue (MB), under a 250 W mercury lamp. The characterization tests confirm that Nb was successfully doped into the crystal structure of NaTaO 3 and the modified NaNb x Ta 1− x O 3 ( x is the doping ratio; x  = 0.25, 0.5, 0.75) samples were formed, which were in regular cubic shapes just like pure NaTaO 3 . The synthesized NaNb x Ta 1− x O 3 ( x  = 0.25, 0.5, 0.75) had improved specific surface area and narrowed band gaps compared with pure NaTaO 3 . In photocatalytic degradation experiments, NaNb 0.75 Ta 0.25 O 3 presented the best photocatalytic activity ascribed to the narrow band gap and the high surface area, degradating 95.7% of MB after 180 min of reaction, which was even twice the ability of pure NaTaO 3 . Besides, the effects of possible inorganic anions and cations in wastewater on photocatalytic degradation were investigated. Electron spin resonance (ESR) tests and capture experiments were also conducted and a possible photocatalytic mechanism was proposed. This work provides a direction for constructing superior NaTaO 3 -based photocatalysts to be widely utilized in environmental protection.