Direct Z-scheme heterojunction of ZnO/MoS2 nanoarrays realized by flowing-induced piezoelectric field for enhanced sunlight photocatalytic performances

Direct Z-scheme heterojunction of ZnO/MoS2 nanoarray on Ni foam has been realized by flowing induced piezoelectric field for enhanced sunlight photocatalytic performances. The porous structure of Ni substrate can effectively induce applied deformation on nanorod arrays and generate built-in piezoelectric field by water flowing. Under sunlight irradiation for 50 min, the photocatalytic degradation efficiency of methyl orange is 50.6 %, and the degradation efficiency rapidly increases to 92.7 % under stirring-sunlight irradiation. The degradation rate increases with increasing stirring speed along an S-shaped relationship. In addition, the heterojunction photocatalyst also performs good repeatability in aqueous solution and even in alkaline solution. The role and amount of active radicals are investigated by radical scavenger experiments and electron spin resonance technique, indicating that only the amount of center dot OH radicals can be significantly increased by flowing induced piezoelectric field. This interesting phenomenon can be attributed to that piezoelectric field converts II-type heterojunction into Z-scheme configuration.