Surface localization of CdZnS quantum dots onto 2D g-C3N4 ultrathin microribbons: Highly efficient visible light-induced H2-generation

The construction of new semiconductor photocatalysts toward high-efficiency splitting water has played an important role in developing sustainable and clean hydrogen energy. In this work, new type of micro/nano-sized hybrids were synthesized based on the assembly of 0D Cd0.5Zn0.5S quantum dots (QDs, size: ca. 5 nm) onto 2D graphitic carbon nitride (g-C3N4) ultrathin microribbons (thickness: ca. 4 nm) via an in-situ growth hydrothermal method. The Cd0.5Zn0.5S 32 wt%@C3N4 composite exhibits the highest visible-light-driven H-2-generation rate of 33.41 mmol h(-)1 g(-1) without any noble-metal as cocatalyst, and the apparent quantum efficiency is 46.65% at 450 nm. Such H-2-generation rate is higher than the pristine g-C3N4 and Cd0.5Zn0.5S by a factor of 27.39 and 9.18 respectively, which is significantly enhanced compared with most as-reported noble-metal-free semiconductor catalysts to date. In addition, compared with the pristine Cd0.5Zn0.5S, the photocatalytical stability of Cd0.5Zn0.5S QDs@C3N4 is highly improved. The enhanced H-2-generation performance can be attributed to the well-matched energy level and strong electronic coupling between two components at the g-C3N4 interface as well as enhanced visible-light absorption. The uniform dispersion of Cd0.5Zn0.5S QDs onto the g-C3N4 ultrathin micro ribbons also facilitates the depression of electron-hole recombination from potential aggregation of Cd0.5Zn0.5S. Therefore, this work supplies an effective way to obtain promising 2D micro/nanostructures for high-efficiency visible light-induced H2-generation. (C) 2016 Elsevier Ltd. All rights reserved.