Abstract <p>The polyacrylamide gel method (PGM) was applied to synthesize pure BaTiO₃ by using tetrabutyl titanate as the titanium source and adding NaOH to the precursor solution. A systematic investigation was performed to analyze the impact of the titanium source, acid, base, and sintering temperature on the purity of the BaTiO₃ phase. Using a PGM with NaOH in the precursor solution, tetrabutyl titanate as the titanium source, and a sintering temperature of 950°C is an effective way to obtain pure BaTiO₃. The BaTiO₃ exhibits high catalytic activity for the degradation of methylene blue (MB) dye under vibration and light irradiation conditions in situ, with or without the addition of 2 mL of H₂O₂. The catalytic experiments proved that the optimal catalyst content, dye concentration, cycle index and H₂O₂ concentration of the BaTiO₃ for the degradation of MB dye were 1.5 g/L, 10 mg/L, 4 and 2 mL, respectively. Under the conditions of ultrasound + light + O₂, BaTiO₃ produced hydrogen peroxide with a concentration of 1135 μmol/g in 180 min, providing conditions for the in-situ generation of hydrogen peroxide and the degradation of MB dye. According to in-situ experiments, BaTiO₃ can degrade MB dye completely within 90 min. A mechanism that combines vibration catalysis and photocatalysis was proposed based on numerous experiments and theoretical discussions. The technical reference provided by this experimental idea can be used by other catalysts to generate hydrogen peroxide in-situ and degrade organic dyes.</p>