Novel reduced graphene oxide-supported Cd0.5Zn0.5S/g-C3N4 Z-scheme heterojunction photocatalyst for enhanced hydrogen evolution

Abstract

A novel reduced graphene oxide (RGO)-supported Cd0.5Zn0.5S/g-C3N4 Z-scheme heterojunctions has been successfully fabricated via a two-step method for enhanced photocatalytic hydrogen generation. The photocatalytic water splitting rate of the RGO-supported Cd0.5Zn0.5S/g-C3N4-40% composite can reach 39.24 mmol∙g−1∙h−1 (λ = 420 nm, QE = 37.88%) without noble metal co-catalyst, which is 8.1 and 48.4 times with respect to pure Cd0.5Zn0.5S and g-C3N4. The enhanced photocatalytic hydrogen evolution performance can be ascribed to the synergistic effect between Cd0.5Zn0.5S nanospheres and g-C3N4 nanosheets in the existence of RGO, which plays a decisive role in the ternary system by acting as a mediator of carriers between the two semiconductors. Photoluminescence spectroscopy and transient photocurrent curves demonstrate that the separation efficiency of photo-generated carriers is significantly improved because of the Z-scheme heterojunction, which is demonstrated by the hydroxyl radical experiment. Besides, the photo-stability of the RGO-supported Cd0.5Zn0.5S/g-C3N4-40% was also investigated.