Sm-Doped (1 – x)Pb(Mg_1/3Nb_2/3)O₃-xPbTiO₃ Nanostructures for Piezocatalytic Dye Degradation

Mechanical energy can be directly transformed into chemical energy by piezoelectric materials, namely, piezocatalysis, which is a potential tactic for renewable clean energy collection and environmental purification. The piezocatalytic efficiency strongly relies on the piezoelectric property and free charge concentration of piezocatalysts. Here, four samarium-doped (1 – x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 nanostructures were designed to investigate the correlation between the piezoelectric property and piezocatalytic performance. The diverse dye degradation efficiencies confirmed the high piezoelectric coefficient toward high catalytic activity. The degradation efficiency for acid orange 7 (AO7) was 100% within 20 min, while those for methyl orange (MO), methylene blue, and rhodamine B dyes were 97, 78, and 72%, respectively, within 40 min under ultrasonic vibration only. Furthermore, high catalytic efficiency of 96% was still maintained for AO7 degradation after 10 consecutive degradation cycles for samarium-doped 0.70Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 due to its high piezoelectric coefficient. The investigation of the catalytic mechanism demonstrated that hole and superoxide radicals were the primary active species toward AO7 degradation, whereas hydroxyl and hole radicals were for MO degradation. This work not only demonstrates the highly efficient catalytic activity of samarium-doped (1 – x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 nanostructures but also gives a deep comprehension of the correlation between the piezoelectric property and catalytic performance of piezocatalysts.