A zero-dimensional/two-dimensional Ag–Ag2S–CdS plasmonic nanohybrid for rapid photodegradation of organic pollutant by solar light

Abstract

Herein, the two synthesis strategies are employed for rational design of 0D/2DAg-Ag2S–CdS heterojunctions towards photocatalytic degradation of methyl orange (MO) under simulated solar light. As the first strategy, a ternary Ag–Ag2S–CdS nanosheet (NS) heterojunction was fabricated via combined cation exchange and photo-reduction (CEPR) method (Ag–Ag2S–CdS/CEPR). The second strategy employed coprecipitation (CP) method (Ag–Ag2S–CdS/CP). Strikingly, SEM, TEM and HR-TEM images are manifested the first strategy is beneficial for retaining the original thickness (20.2 nm) of CdS NSs with a dominant formation of metallic Ag, whereas the second strategy increases the thickness (33.4 nm) of CdS NSs with a dominant formation of Ag2S. The Ag–Ag2S–CdS/CEPR exhibited 1.8-fold and 3.5-fold enhancement in photocatalytic activities as compared to those of Ag–Ag2S–CdS/CP and bare CdS NSs, respectively. This enhanced photocatalytic activity could be ascribed to fact that the first strategy produces a high-quality interface with intimate contact between the Ag–Ag2S–CdS heterojunctions, resulting in enhanced separation of photo-excited charge carriers, extended light absorption, and enriched active-sites. Furthermore, the degradation efficiency of Ag–Ag2S–CdS/CEPR was significantly reduced to ∼5% in the presence of BQ (•O2− scavenger), indicating that •O2− is the major active species that can decompose MO dye under simulated solar light.