Seaweed bio-inspired ZnO piezoelectric cilia array applied in microreactors for enhanced photocatalytic performance

A piezoelectric built-in electric field is believed to be an effective way to separate photoinduced carriers and enhance photocatalytic performance. The ubiquitous and inexhaustible water wave energy might be a good choice for the extra energy needed to actuate the deformation of piezoelectric materials to create an internal electric field. Thus, in order to harness the piezoelectric effect and the water flow energy, seaweed bio-inspired ZnO piezoelectric cilia arrays were fabricated and a microreactor was applied to further enhance their photocatalytic ability owing to its fast mass transfer. By means of the light localization effect, the reflectance of the cilia arrays was reduced by 41% and hence the absorbance increased correspondingly. By comparison with a P1Z0.5 film (P3U7 : ZnO = 1 : 0.5), P1Z0.5 cilia gain a 261% improvement of photocatalytic degradation of tetracycline (TC). In addition, the P1Z0.5 cilia in the microreactor show a 222% increase against those in the bulk reactor when degrading 50 mL of TC. An 83% increase can be seen for ZnO cilia between P3U7 and PDMS substrates, indicating the significant role of the piezoelectric field in photocatalysis. By combining piezoelectric field enhanced ZnO cilia arrays with microreactors, a huge improvement can be observed in photocatalytic degradation results. This work demonstrates a new avenue for taking advantage of the piezoelectric effect to enhance photocatalytic performance by harnessing ubiquitous water flow energy, pointing out another horizon for practical application of photocatalytic technology.