Construction of sugar-gourd-shaped CdS/Co1-xS hollow hetero-nanostructure as an efficient Z-scheme photocatalyst for hydrogen generation

Abstract

Hollow hetero-nanostructures have unique advantages for energy storage and conversion and are highly desirable for their photocatalysis applications. We herein report the synthesis of an unusual sugar-gourd-shaped hollow hetero-nanostructure, Co1-xS hollow polyhedrons (HPs) skewered on CdS nanowires (NWs) (CdS/Co1-xS HHNSs), through a facile two-step strategy of growing ZIF-67 on CdS NWs followed by a sulfidation reaction. The loading amounts of Co1-xS HPs on an individual CdS NW can be adjusted by simply controlling the content of the Co1-xS precursor in the reaction. The coupling of the Co1-xS HPs with the CdS NWs not only broadens the solar light harvesting spectrum from ultraviolet to near infrared region, but also results in abundant Co vacancies as well as sides and facets with lots of active sites. More importantly, in-situ irradiated X-ray photoelectron spectroscopy confirms the direct Z-scheme transfer pathway of photogenerated charge carriers in the hetero-nanostructure, which facilitates the separation of photogenerated electron-hole pairs and induces strong photoreduction ability due to lower aligned conductor band of Co1-xS. As a result, the gular-gourd-shaped CdS/Co1-xS HHNSs are demonstrated as an efficient visible light-driven photocatalyst for H2 production. A H2 production rate of 13.48 mmol g−1 h−1 is achieved with optimized CdS/Co1-xS HHNSs without using any additional co-catalyst. This is the first report on the performance of Co vacancies in Co1-xS hollow nanostructures for photocatalysis which inspire the development of unusual hollow hetero-nanostructures as efficient photocatalysts by means of morphology design and interfacial electronic modulation.