Carbon nitride coupled with CdS-TiO2 nanodots as 2D/0D ternary composite with enhanced photocatalytic H2 evolution: A novel efficient three-level electron transfer process

Photocatalytic H-2 evolution from water splitting requires an efficient photocatalyst with excellent charge separation ability and broad visible-light adsorption region. OD CdS-TiO2 nanodots (NDs) were successfully decorated on the 2D g-C3N4 sheets via an epitaxial growth process. The as-synthesized ternary composite of CdS-TiO2@g-C3N4 exhibits enhanced visible-light-driven photocatalytic H-2 evolution activity, as compared to the binary composites and their single components, which is about 6.7 and 11.2 times higher than those of single CdS and g-C3N4, respectively. Moreover, the as-obtained ternary composite has an external quantum efficiency (EQE) of 11.9% at 420 nm, implying the high utilization efficiency of photo-induced charges. In addition, the superior photostability can be achieved by this coupling method. The enhanced photocatalytic activity was attributed to the efficient charge separation originated from the three-level electron transfer system, the matched energy level positions, the abundant adsorption sites and active sites (OD/2D structure) and the synergistic effect among CdS, TiO2 and g-C3N4. The work present here demonstrated that the construction of this three-level electron transfer system is an effective strategy to design more efficient ternary materials toward solar energy conversion (like H-2 production and CO2 reduction). (C) 2017 Elsevier B.V. All rights reserved.