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 (SnO 2 / t -BaTiO 3 and SnO 2 -Sb/ t -BaTiO 3 ) consisting of an electrocatalyst and piezomaterial, respectively, are designed to investigate the coupled effect of piezocatalytic and electrocatalytic processes on the degradation of pollutants. SnO 2 , especially SnO 2 -Sb, can considerably enhance the piezocatalytic degradation of the antibiotic metronidazole (MNZ). The piezocatalytic rate constants of SnO 2 / t -BaTiO 3 and SnO 2 -Sb/ t -BaTiO 3 are 2.3 and 3.0 times that of t -BaTiO 3 , respectively. In the degradation process, SnO 2 and SnO 2 -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 radicals as well as reduce the formation of 1 O 2 . Significantly, the piezoelectric field can drive not only the free charges of t -BaTiO 3 and its remnant piezoelectric field but also those of the loaded electrocatalyst SnO 2 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.