Coupling effect of piezomaterial and DSA catalyst for degradation of metronidazole: Finding of induction electrocatalysis from remnant piezoelectric filed

Piezocatalysis is an emerging green advanced-oxidation technology for the degradation of toxic pollutants; however, piezomaterials are not generally excellent electrocatalysts. Herein, two complex piezocatalysts (SnO2/t-BaTiO3 and SnO2-Sb/t-BaTiO3) consisting of an electrocatalyst and piezomaterial, respectively, are designed to investigate the coupled effect of piezocatalytic and electrocatalytic processes on the degradation of pollutants. SnO2, especially SnO2-Sb, can considerably enhance the piezocatalytic degradation of the antibiotic metronidazole (MNZ). The piezocatalytic rate constants of SnO2/tBaTiO(3) and SnO2-Sb/t-BaTiO3 are 2.3 and 3.0 times that of t-BaTiO3, respectively. In the degradation process, SnO2 and SnO2-Sb are confirmed to act as dimensionally stable anode-like (DSA-like) catalysts because they can increase the response of the piezoelectrochemical anodic current and the generation of (OH)-O-center dot radicals as well as reduce the formation of O-1(2). Significantly, the piezoelectric field can drive not only the free charges of t-BaTiO3 and its remnant piezoelectric field but also those of the loaded electrocatalyst SnO2 to participate in the degradation of MNZ. These results indicate that the coupling of an excellent electrocatalyst and piezomaterial is an effective method to promote piezocatalytic efficiency. (C) 2019 Elsevier Inc. All rights reserved.