In Situ Growth Facilitating the Piezo-Photocatalytic Effect of Zn1-xCdxS/ZnO Nanorods for Highly Efficient H2 Production.

Abstract

Photocatalytic H2 production holds promise for alleviating energy and environmental issues. The separation of photoinduced charge carriers plays vital roles in enhancing the activity of photocatalytic H2 production. The piezoelectric effect has been proposed to be effective in facilitating the separation of charge carriers. However, the piezoelectric effect is usually restricted by the noncompact contact between the polarized materials and semiconductors. In this study, Zn1-xCdxS/ZnO nanorod arrays on stainless steel for piezo-photocatalytic H2 production are fabricated by an in situ growth method, achieving an electronic-level contact between Zn1-xCdxS and ZnO. The separation and migration of photogenerated charge carriers in Zn1-xCdxS are significantly improved by the piezoelectric effect induced by ZnO under mechanical vibration. Consequently, under solar and ultrasonic irradiation, the H2 production rate of Zn1-xCdxS/ZnO nanorod arrays achieves 20.96 μmol h-1 cm-2, which is 4 times higher than that under solar irradiation. Such a performance can be attributed to the synergies of the piezoelectric field of bent ZnO nanorods and the built-in electric field of the Zn1-xCdxS/ZnO heterostructure, which efficiently separate the photoinduced charge carriers. This study provides a new strategy to couple polarized materials and semiconductors for highly efficient piezo-photocatalytic H2 production.