In Situ Growth Facilitating the Piezo-Photocatalytic Effect of Zn_1-x Cd _x S/ZnO Nanorods for Highly Efficient H₂ Production

Photocatalytic H-2 productionholds promisefor alleviatingenergy and environmental issues. The separation of photoinduced chargecarriers plays vital roles in enhancing the activity of photocatalyticH(2) production. The piezoelectric effect has been proposedto be effective in facilitating the separation of charge carriers.However, the piezoelectric effect is usually restricted by the noncompactcontact between the polarized materials and semiconductors. In thisstudy, Zn1-x Cd x S/ZnO nanorod arrays on stainless steel for piezo-photocatalyticH(2) production are fabricated by an in situ growth method,achieving an electronic-level contact between Zn1-x Cd x S and ZnO. The separationand migration of photogenerated charge carriers in Zn1-x Cd x S are significantlyimproved by the piezoelectric effect induced by ZnO under mechanicalvibration. Consequently, under solar and ultrasonic irradiation, theH(2) production rate of Zn1-x Cd x S/ZnO nanorod arrays achieves20.96 mu mol h(-1) cm(-2), whichis 4 times higher than that under solar irradiation. Such a performancecan be attributed to the synergies of the piezoelectric field of bentZnO nanorods and the built-in electric field of the Zn1-x Cd x S/ZnO heterostructure,which efficiently separate the photoinduced charge carriers. Thisstudy provides a new strategy to couple polarized materials and semiconductorsfor highly efficient piezo-photocatalytic H-2 production.