Construction of CdS quantum dots modified g-C3N4/ZnO heterostructured photoanode for efficient photoelectrochemical water splitting

CdS quantum dots modified g-C3N4/ZnO nanorods core/shell structured photoanode has been designed and hydrothermally grown on electrically conductive fluorine-doped tin oxide substrate (FTO). The CdS/g-C3N4/ZnO heterojunction is sequentially fabricated by one-step hydrothermal method in the g-C3N4 aqueous solution and successive ionic layer adsorption-reaction method. It has been shown that the interface of ternary semi-conductors plays a key role in enhancement of photoelectrochemical activity for water splitting under simulated sunlight illumination. The increase of photocurrent is attributed to the redshift of absorption edge of CdS/g-C3N4/ZnO towards visible light in comparison with CdS/ZnO, g-C3N4/ZnO and pristine ZnO. Moreover, the heterojunction between CdS, g-C3N4 and ZnO can significantly enhance the separation efficiency of photo-generated charge carriers. In addition, g-C3N4 can serve as holes receptor of CdS and act as a protective layer which will reduce the photocorrosion of CdS and improve the stability of photoanode. The optimized of photoanode exhibits an improved PEC performance under visible light irradiation. This work provides a promising strategy for developing ternary photoanode with high stability and efficiency.