Two birds with one stone: Cobalt-doping induces to enhanced piezoelectric property and persulfate activation ability of ZnO nanorods for efficient water purification

Piezocatalysis has attracted increasing attention in recent years for environment remediation. However, the efficiency of single piezocatalysis is not high enough because of the low piezo coefficient of most materials, thus limiting the practical application. Herein, we successfully constructed an advanced oxidation system for pollutants degradation by combining piezocatalysis with persulfate (PS) activation on Co doped ZnO nanorods. Theoretical calculations and experimental results revealed that the doped Co not only improves the piezoelectric property of ZnO, but also acts as the activation sites for PS. A non-radical oriented reaction was identified as the main process for pollutants degradation, and the Co-PS complex (Co-S2O8) was confirmed as the main reactive species in the present piezo assisted PS activation system. Moreover, a water flow stimulated reactor was constructed based on self-generated pressure, and the relations between flow field distribution and catalytic efficiency was revealed by computational fluid dynamics (CFD) simulation. This work opens new prospects for the development of piezo-based catalytic systems for efficient water purification by utilizing the kinetic energy of water flow.