Z-scheme CdS/g-C 3 N 4 composites with RGO as an electron mediator for efficient photocatalytic H 2 production and pollutant degradation

We herein report a novel ternary CdS/reduced graphene oxide (RGO)/graphitic carbon nitride (g-C3N4) hybrid photocatalyst for H2 generation and degradation of atrazine (a potent herbicide) through Z-scheme electron transport. Based on energy band theory, two visible-light-active semiconductors, CdS-coupled RGO and exfoliated g-C3N4 nanosheets (NSs), were coupled to construct Z-scheme hybrids using a hydrothermal process. Compared with the bare photocatalysts, the as-prepared hybrid photocatalysts exhibited efficient H2 generation and atrazine degradation activity owing to improved charge separation and photostability. As the electron mediator, RGO played an important role in accelerating electron transfer at the CdS/g-C3N4 interface via the Z-scheme electron transfer pathway. This Z-scheme charge transfer was verified using various techniques, including photoluminescence, transient photocurrent measurements, and determination of the photocatalyst band potentials. A suitable Z-scheme charge separation mechanism was proposed for the improved H2 generation activity. The intermediates formed during atrazine decomposition were identified, and an explanation for the fragmentation pattern was proposed. The Z-scheme process confers improved charge separation and long-term photostability on the system, and provides new insights for the design of redox-mediator-free RGO-based Z-scheme composites for photocatalysis applications.