One-pot construction of 1D/2D Zn1-xCdxS/D-ZnS(en)(0.5) composites with perfect heterojunctions and their superior visible-light-driven photocatalytic H-2 evolution

摘要

A series of well-defined I D/2D Zn1-X,CdxS/D-ZnS(en)0.5 hybrids are fabricated via an one-pot synthesis method. The resulting composites exhibit enhanced visible-light-driven photoactivities for H-2 production from water in the presence of sacrificial reagents. The optimized Zn0.41Cd0.59S/D-ZnS(en)(0.5) hybrid shows the extremely high H-2 evolution rate of 463.6 mu molH(-1) per 30 mg under visible light irradiation (lambda >420 nm), without any cocatalysts. The highest 1-12 production rate presents 826-fold and 24-fold enhancement compared to pristine D-ZnS(en)0.5 and CdS, respectively. The corresponding apparent quantum yield (AQY) at 440 nm reaches up to 49.95%. The dramatically improved photocatalytic performance could be attributed to the effective interfacial and interior carriers separation. The former is based on the perfect Zn0.41Cd0.59S/D-ZnS(en)(0.5) heterojunctions with well-matched lattice and band structure, which is obtained by collaborative optimization of composition regulation and defect mediation. While the latter is achieved by low dimension control on the basis of the unique electronic behavior in low-dimensional materials. Besides, the stability of Zn0.41Cd0.59S/D-ZnS(en)(0.5) heterostructure is also investigated. Several possible causes of slight deactivation are proposed, which mainly includes the weakened interfacial contact, partial ethylenediamine (en) ligands dissociation or substitution by H2O, OH- and S2-, repair of S vacancies and partial oxidation of Cd-S bonds. It may provide theoretic guidance for further designing high-stability photocatalysts. In addition, the optimized hybrid can be used at ambient pressure and under natural sunlight illumination, and the synthesis method is facile, economic and short-period. Thus our proposed system is highly attractive for large scale energy applications. (C) 2017 Elsevier B.V. All rights reserved.